Patent Publication Number: US-10330877-B2

Title: Binder film system

Description:
RELATED APPLICATIONS 
     This application is a divisional of U.S. application Ser. No. 15/190,738, filed on Jun. 23, 2016, which is a continuation of International Application No. PCT/US14/69237 filed on Dec. 9, 2014, which claims the benefit of priority to U.S. Provisional Application No. 61/921,777, filed Dec. 30, 2013, the content of which is relied upon and incorporated herein by reference in entirety. 
    
    
     BACKGROUND 
     Aspects of the present disclosure relate generally to cables, such as fiber optic cables that may support and carry optical fibers as well as other cable components. More specifically, aspects of the present disclosure relate to a binder film for constraining elements of a cable, such as buffer tubes wound around a central strength member in a core of a fiber optic cable. 
     Loose tube fiber optic cables typically use crisscrossing binder yarns that are counter-helically wrapped about a core of the cable to constrain stranded buffer tubes containing optical fibers, particularly with arrangements of the buffer tubes that include reverse-oscillatory winding patterns of the buffer tubes where the lay direction of the buffer tubes periodically reverses around a (straight) central strength member along the length of the core. The central strength member is typically a rod of a rigid material. Buffer tubes are typically cylindrical tubes (generally 2 to 3 mm in outer diameter) that contain optical fibers. Open space in the interior of a buffer tube may be water-blocked with grease. 
     Applicants have found that stranded buffer tubes, particularly those stranded in a reverse-oscillating pattern, function as a loaded dual-torsion spring with bias to unwind and correspondingly stretch out along the length of the cable. The binder yarns constrain the buffer tubes in the reversals. However, use of binder yarns may limit the length of cable that can be manufactured without stopping a manufacturing line. For example, due to finite lengths of binder yarns on a bobbin, the manufacturing line may be stopped every 20 kilometers (km) to switch out bobbins. Stopping the manufacturing line and switching out components reduces efficiency. Further, binder yarns may impart distortions or stress concentrations in the stranded buffer tubes, where the binder yarns pass over the respective buffer tubes, potentially resulting in attenuation of optical fibers therein. The level of attenuation is a function of the tension in the binder yarns, which itself may be a function of the number, arrangement, structure, and materials of the buffer tubes, among other variables. Application of binder yarns may accordingly limit the speed of a stranding machine, depending upon allowable binder-yarn tension. A need exists for a binder system that allows for faster manufacturing of cables, reduces potential for attenuation of optical fibers in the cables (such as by avoiding point loading of buffer tubes), and/or allows for long, continuous lengths of such cables to be efficiently manufactured. 
     To this end, Applicants have experimented with manufacturing stranded cable cores without binder yarns. In one experiment, Applicants attempted to extrude a thin film over a core of stranded buffer tubes with binder yarns removed. The buffer tubes had previously conformed to the stranding pattern about the core and the pattern remained when the binder yarns were removed. However, a “bird cage” (also called “bird nest”) or jumble of stranded buffer tubes appeared upon extruding the thin film, which became more and more pronounced until the manufacturing line had to be stopped. Applicants theorize that the buffer tubes migrated axially forcing them outward and away from the central strength member when the binder yarns were removed. The jacket did not cool (and constrict) fast enough, with the stranded buffer tubes held down, to sufficiently couple the stranded buffer tubes to the central strength member of the cable. Instead, the buffer tubes shifted axially due to release of spring forces and pull of the extrusion cone, creating the “bird&#39;s cage.” 
     In another experiment, Applicants circumferentially taped only the reversal points of the stranded buffer tubes and to then extruded a jacket over the taped stranded buffer tubes. However, with this experiment a “bird cage” formed, resulting in bulges in the cable just prior to each reversal point of the stranded buffer tubes along the length of the cable. Applicants theorize that the stranded buffer tubes shifted axially between reversals. Release of spring forces in the stranded buffer tubes lifted the buffer tubes away from the central strength member. Axial loading (pulling) on the stranded elements by the extrusion cone then moved the buffer tubes axially, where excess length built up until coupling occurred with the tape. In view of the experimentation, a need exists for a binder system that overcomes some or all of the drawbacks associated with binder yarns, while limiting and/or controlling the impact of unwinding, outward- and axial-migration of the buffer tubes due spring forces in stranded buffer tubes and axial forces from extrusion. 
     SUMMARY 
     One embodiment relates to a fiber optic cable, which includes a core and a binder film surrounding the core. The core includes a central strength member and core elements, such as buffer tubes containing optical fibers, where the core elements are stranded around the central strength member in a pattern of stranding including reversals in lay direction of the core elements. The binder film is in radial tension around the core such that the binder film opposes outwardly transverse deflection of the core elements. Further, the binder film loads the core elements normally to the central strength member such that contact between the core elements and central strength member provides coupling therebetween, limiting axial migration of the core elements relative to the central strength member. 
     Another embodiment relates to a fiber optic cable, which includes a core of the cable having at least one optical fiber, a binder film surrounding the core, and powder particles. The binder film is in tension around the core. The powder particles are water-absorbing powder particles that include a super-absorbent polymer. At least some of the powder particles are attached to the binder film. 
     Yet another embodiment relates to a method of manufacturing a fiber optic cable, which includes a step of stranding core elements around a central strength member in a pattern of stranding including reversals in lay direction of the core elements. The core elements include a buffer tube surrounding at least one optical fiber, and one or more additional core elements. The one or more additional core elements include at least one of a filler rod and an additional buffer tube. The method includes a step of extruding a binder film to surround the core elements immediately after stranding the core elements, within a distance of at least ten lay lengths of the strand from the closing point where the core elements come together in the pattern of stranding of the core. The method may further include a step of constraining the stranded core elements while the binder film contracts and cools, thereby allowing the binder film to load the stranded core elements against the central strength member to arrest axial migration of the stranded core elements during manufacturing of the cable. 
     In some embodiments the binder film is twisted around the core and is applied to the core by a rotating extruder. Twisting of the binder film during the extrusion thereof is intended to increase the rate at which the binder film draws down onto the core and/or to increase inward radial tension of the binder film. 
     Additional features and advantages are set forth in the Detailed Description that follows, and in part will be readily apparent to those skilled in the art from the description or recognized by practicing the embodiments as described in the written description and claims hereof, as well as the appended drawings. It is to be understood that both the foregoing general description and the following Detailed Description are merely exemplary, and are intended to provide an overview or framework to understand the nature and character of the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The accompanying Figures are included to provide a further understanding, and are incorporated in and constitute a part of this specification. The drawings illustrate one or more embodiments, and together with the Detailed Description serve to explain principles and operations of the various embodiments. As such, the disclosure will become more fully understood from the following Detailed Description, taken in conjunction with the accompanying Figures, in which: 
         FIG. 1  is a cross-sectional view of a fiber optic cable according to an exemplary embodiment. 
         FIGS. 2A and 2B  are schematic diagrams of binder films according to exemplary embodiments. 
         FIG. 3  is a cross-sectional view of a fiber optic cable according to another exemplary embodiment. 
         FIGS. 4-6  are schematic diagrams of cables being manufactured according to various exemplary embodiments. 
         FIG. 7  is a perspective view of a binder film being extruded around a core of stranded elements according to an exemplary embodiment. 
         FIG. 8  is a digital image of a fiber optic cable having a core of stranded elements bound by the binder film of  FIG. 7  in a jacket according to an exemplary embodiment. 
         FIG. 9  is a graphical representation of heat flow versus temperature for polyethylene and polypropylene samples. 
         FIG. 10  is a digital image of a sample of stranded elements bound around a central strength member, with the central strength member projecting from ends thereof so that the sample is configured for a pull-through test to measure coupling force, according to an exemplary embodiment. 
         FIG. 11  is a digital image of the sample of  FIG. 10  in a pull-through test rig, with the central strength member fixed in a clamp and a tensile test apparatus configured to pull the stranded elements axially upward relative to the central strength member to determine the coupling force, according to an exemplary embodiment. 
         FIG. 12  is a digital image of a core of stranded elements bound by a binder film according to another exemplary embodiment. 
         FIG. 13  is a digital image of the core of  FIG. 12  with the binder film torn away from an end of the core to release the stranded elements and the central strength member according to an exemplary embodiment. 
         FIG. 14  is a digital image of the core of  FIG. 12  with a lengthwise cut through the binder film at a mid-span location to provide access to the stranded elements according to an exemplary embodiment. 
         FIG. 15  is a digital image of the core of  FIG. 12  with a stranded element extricated through the cut of  FIG. 14  and opened to provide access to optical fibers therein according to an exemplary embodiment. 
         FIG. 16  is a cross-sectional view of a fiber optic cable according to an exemplary embodiment. 
         FIG. 17-19  are cross-sectional views of a fiber optic cables (and/or bound cores thereof) according to exemplary embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     Before turning to the following Detailed Description and Figures, which illustrate exemplary embodiments in detail, it should be understood that the present inventive technology is not limited to the details or methodology set forth in the Detailed Description or illustrated in the Figures. For example, as will be understood by those of ordinary skill in the art, features and attributes associated with embodiments shown in one of the Figures or described in the text relating to one of the embodiments may well be applied to other embodiments shown in another of the Figures and/or described elsewhere in the text. 
     Referring to  FIG. 1 , a cable in the form of a fiber optic cable  110  may be an outside-plant loose tube cable, an indoor cable with fire-resistant/retardant properties, an indoor/outdoor cable, or another type of cable, such as a datacenter interconnect cable with micro-modules or a hybrid fiber optic cable including conductive elements. According to an exemplary embodiment, the cable  110  includes a core  112  (e.g., sub-assembly, micro-module), which may be located in the center of the cable  110  or elsewhere and may be the only core of the cable  110  or one of several cores. According to an exemplary embodiment, the core  112  of the cable  110  includes core elements  114 . 
     In some embodiments, the core elements  114  include a tube  116 , such as a buffer tube surrounding at least one optical fiber  118 , a tight-buffer surrounding an optical fiber, or other tube. According to an exemplary embodiment, the tube  116  may contain two, four, six, twelve, twenty-four or other numbers of optical fibers  118 . In contemplated embodiments, the core elements  114  additionally or alternatively include a tube  116  in the form of a dielectric insulator surrounding a conductive wire or wires, such as for a hybrid cable. 
     In some embodiments, the tube  116  further includes a water-blocking element, such as gel (e.g., grease, petroleum-based gel) or an absorbent polymer (e.g., super-absorbent polymer particles or powder). In some such embodiments, the tube  116  includes yarn  120  carrying (e.g., impregnated with) super-absorbent polymer, such as at least one water-blocking yarn  120 , at least two such yarns, or at least four such yarns per tube  116 . In other contemplated embodiments, the tube  116  includes super-absorbent polymer without a separate carrier, such as where the super-absorbent polymer is loose or attached to interior walls of the tube. In some such embodiments, particles of super-absorbent polymer are partially embedded in walls of the tube  116  (interior and/or exterior walls of the tube) or bonded thereto with an adhesive. For example, the particles of super-absorbent polymer may be pneumatically sprayed onto the tube  116  walls during extrusion of the tube  116  and embedded in the tube  116  while the tube  116  is tacky, such as from extrusion processes. 
     According to an exemplary embodiment, the optical fiber  118  of the tube  116  is a glass optical fiber, having a fiber optic core surrounded by a cladding (shown as a circle surrounding a dot in  FIG. 1 ). Some such glass optical fibers may also include one or more polymeric coatings. The optical fiber  118  of the tube  116  is a single mode optical fiber in some embodiments, a multi-mode optical fiber in other embodiments, a multi-core optical fiber in still other embodiments. The optical fiber  118  may be bend resistant (e.g., bend insensitive optical fiber, such as CLEARCURVE™ optical fiber manufactured by Corning Incorporated of Corning, N.Y.). The optical fiber  118  may be color-coated and/or tight-buffered. The optical fiber  118  may be one of several optical fibers aligned and bound together in a fiber ribbon form. 
     According to an exemplary embodiment, the core  112  of the cable  110  includes a plurality of additional core elements (e.g., elongate elements extending lengthwise through the cable  110 ), in addition to the tube  116 , such as at least three additional core elements, at least five additional core elements. According to an exemplary embodiment, the plurality of additional core elements includes at least one of a filler rod  122  and/or an additional tube  116 ′. In other contemplated embodiments, the core elements  114  may also or alternatively include straight or stranded conductive wires (e.g., copper or aluminum wires) or other elements. In some embodiments, the core elements are all about the same size and cross-sectional shape (see  FIG. 1 ), such as all being round and having diameters of within 10% of the diameter of the largest of the core elements  114 . In other embodiments, core elements  114  may vary in size and/or shape. 
     Referring now to  FIGS. 1-2 , the cable  110  includes a binder film  126  (e.g., membrane) surrounding the core  112 , exterior to some or all of the core elements  114 . The tube  116  and the plurality of additional core elements  116 ′,  122  are at least partially constrained (i.e., held in place) and directly or indirectly bound to one another by the binder film  126 . In some embodiments, the binder film  126  directly contacts the core elements  114 . For example, tension T in the binder film  126  (see also  FIG. 2A ) may hold the core elements  114  against a central strength member  124  and/or one another. The loading of the binder film  126  may further increase interfacial loading (e.g., friction) between the core elements  114  with respect to one another and other components of the cable  110 , thereby constraining the core elements  114 . 
     According to an exemplary embodiment, the binder film  126  includes (e.g., is formed from, is formed primarily from, has some amount of) a polymeric material such as polyethylene (e.g., low-density polyethylene, medium density polyethylene, high-density polyethylene), polypropylene, polyurethane, or other polymers. In some embodiments, the binder film  126  includes at least 70% by weight polyethylene, and may further include stabilizers, nucleation initiators, fillers, fire-retardant additives, reinforcement elements (e.g., chopped fiberglass fibers), and/or combinations of some or all such additional components or other components. 
     According to an exemplary embodiment, the binder film  126  is formed from a material having a Young&#39;s modulus of 3 gigapascals (GPa) or less, thereby providing a relatively high elasticity or springiness to the binder film  126  so that the binder film  126  may conform to the shape of the core elements  114  and not overly distort the core elements  114 , thereby reducing the likelihood of attenuation of optical fibers  118  corresponding to the core elements  114 . In other embodiments, the binder film  126  is formed from a material having a Young&#39;s modulus of 5 GPa or less, 2 GPa or less, or a different elasticity, which may not be relatively high. 
     According to an exemplary embodiment, the binder film  126  is thin, such as 0.5 mm or less in thickness (e.g., about 20 mil or less in thickness, where “mil” is 1/1000th inch). In some such embodiments, the film is 0.2 mm or less (e.g., about 8 mil or less), such as greater than 0.05 mm and/or less than 0.15 mm. In some embodiments, the binder film  126  is in a range of 0.4 to 6 mil in thickness, or another thickness. In contemplated embodiments, the film may be greater than 0.5 mm and/or less than 1.0 mm in thickness. In some cases, for example, the binder film  126  has roughly the thickness of a typical garbage bag. The thickness of the binder film  126  may be less than a tenth the maximum cross-sectional dimension of the cable, such as less than a twentieth, less than a fiftieth, less than a hundredth, while in other embodiments the binder film  126  may be otherwise sized relative to the cable cross-section. In some embodiments, when comparing average cross-sectional thicknesses, the jacket  134  is thicker than the binder film  126 , such as at least twice as thick as the binder film  126 , at least ten times as thick as the binder film  126 , at least twenty times as thick as the binder film  126 . In other contemplated embodiments, the jacket  134  may be thinner than the binder film  126 , such as with a 0.4 mm nylon skin-layer jacket extruded over a 0.5 mm binder film. 
     The thickness of the binder film  126  may not be uniform around the bound stranded elements  114 . Applicants have found some migration of the material of the binder film  126  during manufacturing. For example, the belts  322  (e.g., treads, tracks) of the caterpuller  320  shown in  FIGS. 4-6  impart compressive forces on the binder film  126  that may somewhat flatten the binder film  126  on opposing sides thereof, as the binder film  126  solidifies and contracts to hold the stranded elements  114  to the central strength member  124 . As such, the “thickness” of the binder film  126 , as used herein, is an average thickness around the cross-sectional periphery. For example, the somewhat flattened portions of the binder film  126  caused by the caterpuller  320  may be at least 20% thinner than the adjoining portions of the binder film  126  and/or the average thickness of the binder film  126 . 
     Use of a relatively thin binder film  126  allows for rapid cooling (e.g., on the order of milliseconds, as further discussed with regard to the process  310  shown in  FIGS. 4-6 ) of the binder film  126  during manufacturing and thereby allowing the binder film  126  to quickly hold the core elements  114  in place, such as in a particular stranding configuration, facilitating manufacturing. By contrast, cooling may be too slow to prevent movement of the stranded core elements when extruding a full or traditional jacket over the core, without binder yarns (or the binder film); or when even extruding a relatively thin film without use of a caterpuller (e.g., caterpuller  320  as shown in  FIG. 4 ; sometimes called a “caterpillar”) or other assisting device. However such cables are contemplated to include technology disclosed herein (e.g., coextruded access features, embedded water-swellable powder, etc.) in some embodiments. Subsequent to the application of the binder film  126 , the manufacturing process may further include applying a thicker jacket  134  to the exterior of the binder film  126 , thereby improving robustness and/or weather-ability of the cable  110 . In other contemplated embodiments, the core  112 , surrounded by the binder film  114 , may be used and/or sold as a finished product (see generally  FIGS. 2A and 2B ). 
     Still referring to  FIG. 1 , the cable  110  further includes the central strength member  124 , which may be a dielectric strength member, such as an up jacketed glass-reinforced composite rod. In other embodiments, the central strength member  124  may be or include a steel rod, stranded steel, tensile yarn or fibers (e.g., bundled aramid), or other strengthening materials. As shown in  FIG. 1 , the central strength member  124  includes a center rod  128  and is up jacketed with a polymeric material  130  (e.g., polyethylene, low-smoke zero-halogen polymer). 
     According to an exemplary embodiment, powder particles  132 , such as super-absorbent polymer and/or another powder (e.g., talc), or another water-absorbing component (e.g., water-blocking tape, water-blocking yarns) are attached to the outer surface of the central strength member  124 . At least some of the powder particles  132  may be partially embedded in the up-jacket  130 , and attached thereto by pneumatically spraying the particles  132  against the up jacket  130  while the up jacket  130  is in a tacky and/or softened state. The powder particles  132  may increase or otherwise affect coupling between the central strength member  124  and the core elements  114  around the central strength member  124 . 
     Alternatively or in addition thereto, the particles  132  may be attached to the up jacket  130  with an adhesive. In some embodiments, the central strength member  124  includes the rod  128  without an up-jacket, and the particles  132  may be attached to the rod  128 . In contemplated embodiments, a strength member, such as a glass-reinforced rod or up jacketed steel rod, includes super-absorbent polymer or other particles  132  attached to the outer surface thereof, as disclosed above, without the strength member being a central strength member. 
     In some embodiments, the core elements  114  are stranded (i.e., wound) about the central strength member  124 . The core elements  114  may be stranded in a repeating reverse-oscillatory pattern, such as so-called S-Z stranding (see generally  FIGS. 4-6 ), or other stranding patterns (e.g., helical). The binder film  126  may constrain the core elements  114  in the stranded configuration, facilitating mid-span (see  FIGS. 14-15 ) or cable-end (see  FIG. 13 ) access of the optical fibers  118  and cable bending, without the core elements  114  releasing tension by expanding outward from the access location or a bend in the core  112  of the cable  110 . 
     In other contemplated embodiments, the core elements  114  are non-stranded. In some such embodiments, the core elements  114  include micro-modules or tight-buffered optical fibers that are oriented generally in parallel with one another inside the binder film  126 . For example, harness cables and/or interconnect cables may include a plurality of micro-modules, each including optical fibers and tensile yarn (e.g., aramid), where the micro-modules are bound together by the binder film  126  (see generally  FIGS. 2A and 2B ). Some such cables may not include a central strength member. Some embodiments include multiple cores or sub-assemblies, each bound by a binder film  126 , and jacketed together in the same carrier/distribution cable, possibly bound together with another binder film. For some such embodiments, techniques disclosed herein for rapid cooling/solidification during extrusion and inducing radial tension in the binder film  126  for coupling to a central strength member  124  may be unnecessary for manufacturing. 
       FIG. 3  includes a cable  210  having some components similar to the cable  110 , such as the binder film  126 . Features of the cable  110  and the cable  210  can be mixed and matched in different combinations to form other cables according to the disclosure herein. 
     Referring now to  FIGS. 1 and 3 , in some embodiments the binder film  126  of the cable  110 ,  210  includes powder particles  136 , which may be used for providing water blocking and/or for controlling coupling (e.g., decoupling) of adjoining surfaces in the cable  110 . In some embodiments, the powder particles  132 ,  136  have an average maximum cross-sectional dimension of 500 micrometers (μm) or less, such as 250 μm or less, 100 μm or less. Accordingly, the particles  132 ,  136  may be larger than water-blocking particles that may be used inside the tubes  116 , impregnated in yarns or embedded in interior walls of the tubes  116  as disclosed above, which may have an average maximum cross-sectional dimension less than 75 μm, to mitigate optical fiber micro-bend attenuation. 
     In some embodiments, at least some of the powder particles  136  are coupled directly or indirectly to the binder film  126  (e.g., attached bound directly thereto, adhered thereto, in contact therewith), such as coupled to a surface of the binder film  126 , coupled to an exterior surface of the binder film  126 , coupled to an outside surface of the binder film  126  and/or an inside surface of the binder film  126 . According to an exemplary embodiment, at least some of the powder particles  136  are partially embedded in the binder film  126 , such as passing partly through a surrounding surface plane of the binder film  126  while partially projecting away from the surface of the binder film  126 ; or, put another way, having a portion thereof submerged in the binder film  126  and another portion thereof exposed. In some embodiments, a rotating die may be used to increase normal force on the tubes. 
     The powder particles  136  may be attached to the binder film  126  by pneumatically spraying the powder particles onto the binder film  126 , into and outside of the associated extrusion cone (see also  FIG. 7 ), as further discussed below with regard to  FIGS. 4-6 . The pneumatic spraying may also facilitate rapid cooling of the binder film  126 . In other embodiment, static electricity or other means may be used to motivate the powder particles  136  to embed in the binder film  126  or otherwise couple thereto. In other embodiments, glues or other attachment means are used to attach the powder particles  136  to the binder film  126 . Use of the binder film  126  as a carrier for super-absorbent polymer particles may remove need for water-blocking tape between the core and cable components outside the core, as well as remove need for binder yarn to hold the water-blocking tape in place. In still other embodiments, powder particles may be present but loose and/or not attached to the binder film  126 . In contemplated embodiments, the binder film  126  may be coated with a continuous water-blocking material/layer, or may include other types of water-blocking elements or no water-blocking elements. 
     According to an exemplary embodiment, the powder particles  132 ,  136  include super-absorbent polymer particles, and the amount of super-absorbent polymer particles is less than 100 grams per square meter of surface area (g/m 2 ) of the respective component to which the powder particles are coupled (central strength member  124  or binder film  126 ). In some such embodiments, the amount of super-absorbent polymer particles is between 20 and 60 g/m 2 , such as between 25 and 40 g/m 2 . According to an exemplary embodiment, the amount of super-absorbent polymer or other water-blocking elements used in the cable is at least sufficient to block a one-meter pressure head of tap water in a one-meter length of the cable  110 ,  210 , according to industry standard water penetration tests, which may correspond to the above quantities, depending upon other characteristics of the respective cable  110 ,  210 , such as interstitial spacing between core elements  114 . 
     According to an exemplary embodiment, at least some of the powder particles  136  are positioned on an inside surface of the binder film  126  (see  FIG. 1 ) between the binder film  126  and the core elements  114 . In addition to blocking water, such placement may mitigate adhesion between the binder film  126  and the core elements  114  during manufacturing of the cable  110 ,  210 , such as if the binder film  126  is tacky from extrusion or other manufacturing approaches, such as laser welding or heat softening. Alternatively or in combination therewith, in some embodiments, at least some of the powder particles  136  are positioned on an outside surface of the binder film  126  (see  FIG. 3 ). 
     Powder particles  136  positioned on the outside surface of the binder film  126  may provide water blocking between the binder film  126  and components of the cable  210  exterior thereto, such as metal or dielectric armor  138  ( FIG. 3 ) or micro-modules outside the core  112 . The armor  138 , as shown in  FIG. 3 , may be corrugated steel or another metal and may also serve as a ground conductor, such as for hybrid fiber optic cables having features disclosed herein. Use of a film binder, instead of a thicker layer, allows a narrower “light armor” design, where there is no jacket between the armor  138  and the core  112 . Alternatively, the armor  138  may be dielectric, such as formed from a tough polymer (e.g., some forms of polyvinyl chloride). 
     According to an exemplary embodiment, embedded material discontinuities  140  ( FIG. 3 ) in the jacket  134 , such as narrow strips of co-extruded polypropylene embedded in a polyethylene jacket  134 , may provide tear paths to facilitate opening the jacket  134 . Alternatively, ripcords  142  ( FIG. 1 ) in or adjoining the jacket  134  may facilitate opening the jacket  134 . The powder particles  136  may further facilitate stripping the jacket  134  from the core  112  by decoupling surfaces adjacent to the powder particles  136 . As such, depending upon placement of the powder particles  136 , the particles  136  may facilitate decoupling of the jacket  134  from the binder film  126 , such as for the cable  110  shown in  FIG. 1  where the jacket  134  and binder film  126  are adjoining (i.e., particles  136  placed between the jacket  134  and binder film  126 ), and/or may facilitate decoupling of the binder film  126  from the core elements  114  (i.e., particles  136  placed between the binder film  126  and core elements  114 ). 
     In some embodiments, the jacket  134  and binder film  126  may blend together during extrusion of the jacket  134  over the binder film  126 , particularly if the jacket  134  and the binder film  126  are formed from the same material without powder particles  136  therebetween. In other embodiments, the jacket  134  and the binder film  126  may remain separated or at least partially separated from one another such that each is visually distinguishable when the cable  110 ,  210  is viewed in cross-section. In some embodiments, the binder film  126  and the jacket  134  are not colored the same as one another. For example, they may be colored with visually distinguishable colors, having a difference in “value” in the Munsell scale of at least 3. For example, the jacket  134  may be black while binder film  126  may be white or yellow, but both including (e.g., primarily consisting of, consisting of at least 70% by weight) polyethylene. 
     In some contemplated embodiments, the jacket  134  is opaque, such as colored black and/or including ultra-violet light blocking additives, such as carbon-black; but the binder film  126  is translucent and/or a “natural”-colored polymer, without added color, such that less than 95% of visible light is reflected or absorbed by the binder film  126 . Accordingly, in at least some such embodiments, upon opening or peeling back the jacket  134  away from the binder film  126  and core  112 , the tube  116  and at least some of the plurality of additional core elements  114  are at least partially visible through the binder film  126  while being constrained thereby with the binder film  126  unopened and intact, such as visible upon directing light from a 25 watt white light-bulb with a 20-degree beam directly on the binder film  126  from a distance of one meter or less in an otherwise unlit room. In contemplated embodiments, the core includes a tape or string (e.g., polymeric ripcord), beneath the binder film  126  and visible through the binder film  126 , which may include indicia as to contents of the core  112  or a particular location along the length of the cable  110 . 
     According to an exemplary embodiment, the binder film  126  is continuous peripherally around the core, forming a continuous closed loop (e.g., closed tube) when viewed from the cross-section, as shown in  FIGS. 1-3 , and is also continuous lengthwise along a length of the cable  110 ,  210 , where the length of the cable  110 ,  210  is at least 10 meters (m), such as at least 100 m, at least 1000 m, and may be stored on a large spool. In other contemplated embodiments, the cable  110 ,  210  is less than 10 m long. 
     In some embodiments, around the cross-sectional periphery of the binder film  126 , the binder film  126  takes the shape of adjoining core elements  114  and extends in generally straight paths over interstices  144  ( FIG. 2A ) between the core elements  114 , which may, in some embodiments, result in a generally polygonal shape of the binder film  126  with rounded vertices, where the number of sides of the polygon corresponds to the number of adjoining core elements  114 . 
     In some embodiments, the binder film  126  arcs into the interstices  144  ( FIG. 2B ) so that the binder film  126  does not extend tangentially between adjoining core elements  114 , but instead undulates between concave arcs  146  and convex arcs  148  around the periphery of the stranded elements  114  and intermediate interstices  144 . The concave arcs  148  may not be perfect circular arcs, but instead may have an average radius of curvature that is greater than the radius of one or all of the stranded elements  114  and/or the central strength member  124 . Put another way, the degree of concavity of the concave arcs  146  is less than the degree of convexity of the convex arcs  148 . Applicants theorize that the undulation between concave arcs  146  and convex arcs  148  constrains the stranded elements  114 , opposing unwinding of the stranded elements  114  about the central strength member  124 . Applying a vacuum to the interior of the extrusion cone (see space  316  in  FIGS. 4-6 ; see also  FIG. 7 ) may increase the draw-down rate of the extrudate, and may facilitate formation of the concave arcs  146 . Applicants further believe that the undulation and concave arcs  146  increase the torsional stiffness of the binder film  126 . 
     Use of a continuous binder film  126  may block water from being able to reach the core  112 . In other embodiments, the binder film  126  includes pinholes or other openings. In some contemplated embodiments, binder films may be extruded in a criss-crossing net mesh pattern of film strips, or as a helical or counter-helical binder film strip(s), such as via rotating cross-heads or spinnerets. Either the core or the cross-head may be rotated, and the core may be rotated at a different rate than the cross-head, or vice versa. In other contemplated embodiments, a pre-formed curled or C-shaped tube may be used as the binder  126 , where the core  112  is bound thereby. 
     Referring once more to  FIGS. 2A-2B , in some embodiments the binder film  126  is in tension T around the core  112 , where hoop stress is spread relatively evenly around the transverse (i.e., cross-sectional) periphery of the binder film  126  where the binder film  126  overlays (e.g., contacts directly or indirectly) elements of the core  112 . As such, the binder film  126  opposes outwardly transverse deflection of the core elements  114  relative to the rest of the cable  110 ,  210 , such as outward torsional spring force of S-Z stranded core elements  114 , buckling deflection of un-stranded core elements  114 , such as flat fiberglass yarns, or other loading. As such, the tension T in the binder film  126  may improve cable stability and integrity, such as in compression of the cable  110 ,  210 . 
     In some embodiments, the tension T of the binder film  126  has a distributed loading of at least 5 newtons (N) per meter (m) length of the cable  110 ,  210 , which may be measured by measuring the average diameter of an intact binder film  126  surrounding the core elements  114 , then opening the binder film  126 , removing the core elements  114 , allowing time for the binder film  126  to contract to an unstressed state (e.g., at least a day, depending upon material) at constant temperature, then measuring the decrease in binder film  126  widthwise dimension (i.e., compared to the average periphery). The tension T is the loading required to stretch the binder film  126  to the original width. 
     Referring now to  FIGS. 4-6 , the binder film  126  (shown as an extrusion cone contracting about the core  112  along the manufacturing line direction L) may be applied in conjunction with the manufacturing process or method  310 , which may include stranding (see also  FIG. 7 ). In some such embodiments, the core elements  114  (see also  FIGS. 1-3 ) (e.g., buffer tubes) are stranded by extending an oscillating nose piece  312  through a crosshead and into a space  316  surrounded by the extrudate cone of the binder film  126 , as shown in  FIGS. 4-6 . In some embodiments, the binder film  126  is extruded around the core elements  114  immediately after the core elements  114  are stranded around the central strength member  124 , such as within a distance of at least ten lay lengths (e.g., within six lay lengths) of the strand from the closing point of the core elements  114 , where the core elements  114  come together at the trailing end of the stranding machine in the pattern of stranding of the core  112 . Close proximity of the stranding machine and the extruder essentially allows the stranding machine to compensate for slipping between the stranded elements  114  and the central strength member  124 , such as due to the pull of the extrusion cone (prior to coupling between the stranded elements  114  and the central strength member  124  by the binder film  126  and/or caterpuller  320 ). 
     An industry-standard definition for the lay length of helically stranded elements (e.g., helical lay length) is the lengthwise distance along the cable (and along a central strength member, if present) for a full turn of the stranded elements about the lengthwise axis of the cable (e.g., the length through the center of a single helical spiral). An industry-standard definition for the lay length of reverse-oscillatory stranded elements, such as SZ stranded elements, is the lengthwise distance between reversal points of the strand divided by the sum of turns of the stranded elements (such as turns about a central strength member) between the reversal points, which may include a fraction of a turn; akin to the “average” helical lay length. 
     In the space  316  and outside the extrudate cone of the binder film  126 , powder particles  136  (see  FIG. 6 ), such as super-absorbent polymer particles (e.g., Cabloc® GR-111), may be embedded in the binder film  126  by pneumatic conveyance, such as by being carried and deposited via a spinning vortex of turbulent air flow in a chamber  314  ( FIG. 6 ) outside the extrudate cone of the binder film  126  and/or by being drawn into a high-pressure air flow by a venturi nozzle and carried thereby until accelerated and then released from the air flow via a conventional nozzle in or directed to the interior of the extrudate cone of the binder film  126 . According to such an embodiment, momentum of the powder particles  136  causes them to impact walls of the molten extrudate cone of the binder film  126 . The force of impact and the state of the extrudate (e.g., polyethylene) causes the particles to mechanically adhere to the binder film  126 , but may not arrest elongation of the extrudate, permitting the extrudate to continue to draw/shrink to a relatively thin film that may form tightly around the core elements  114 . 
     Air flows carrying the powder particles  136  may synergistically be used to hasten cooling of the binder film  126 , and may still further be used to shape or thin-out the binder film  126 . Additional flows of cooling fluid  318  (e.g., dry air if associated binder film  126  surface(s) are with super-absorbent polymer particles; fine water mist or water bath, if surfaces are without super-absorbent polymer particles) may be used to further hasten cooling of the binder film  126  so that the binder film  126  will be sufficiently cooled and solidified in order to constrain the core elements  114  within fractions of a second after stranding of the core elements  114 . Furthermore, air flows carrying the powder particles  136  may be coordinated on opposite sides of the binder film to control shaping of the binder film  126  and/or prevent distortion of the binder film  126 . Adherence of the particles  136  to the binder film  126  may assist containing the particles  136  during cable end- and mid-span access. 
     In some embodiments, the binder film  126  is continuous and watertight, which may prevent the powder particles  136  (e.g., super-absorbent polymer particles) in the interior of the binder film  126  from absorbing moisture or water on the exterior of the binder film  126 . To prevent axial migration of water along the exterior of the binder film  126 , between the binder film  126  and additional cabling layers—such as metallic armor, nonmetallic armor, additional strength elements, and/or an additional exterior jacket over the cable core; the powder particles  136  may be applied to the exterior of the binder film  126  while the binder film  126  is still molten and immediately prior to receipt of the cable  110 ,  210  by an anti-torsion caterpuller  320 . The caterpuller  320  may be particularly useful for reverse-oscillatory stranding patterns, such as so-called “SZ” strands, because the caterpuller  320  holds down and constrains the reversal. As such, the caterpuller is preferably positioned within a distance of at least one lay length of the strand from the closing point of the core elements  114 , where the core elements  114  come together at the trailing end of the stranding machine in the pattern of stranding of the core  112 . The extrusion head  414  and extrudate cone (see  FIG. 7 ) is located between the stranding machine and the caterpuller  320 . 
     Particularly in stranding arrangements of core elements  114  that include reverse-oscillatory winding patterns (e.g., S-Z stranding), the anti-torsion caterpuller  320  may serve to apply an opposing torque to torque induced by tension and rotation of the core elements  114 . Belts  322  of the anti-torsion caterpuller  320  may be coupled together so that the belts  322  register on the centerline of the cable  110 ,  210 , which permits automatic adjustment of the spacing of the belts for different cable diameters. According to an exemplary embodiment, the caterpuller  320  is located within 100 mm of the release point of the oscillating nose piece  312  or the closing point of the core elements  114 , where the core elements  114  come together, such as to contact one another and/or a central strength member (see, e.g., central strength member  124  as shown in  FIG. 1 ). Close proximity of the caterpuller  320  and closing point of the core elements  114  prevents the core elements  114  from unwinding when the strand direction is reversed. The caterpuller  320  also isolates tension of individual core elements  114  on the incoming side thereof, reducing the likelihood of distorting desired shapes of the binder film as the core  112  (see also  FIGS. 1-3 ) is formed. Further, the caterpuller  320  allows the binder film  126  to cool quickly while not under load from released spring forces of the stranded elements  114  (which are constrained instead by the belts of the caterpuller  320 ). As such, the binder film  126  is able to cool and constrict to a degree that applies a load to the stranded elements  114  that compresses the elements  114  against the central strength member  124 , providing coupling therebetween. Without the caterpuller  320  and/or cooling pneumatic air flow  318 , the binder film  126  may be outwardly loaded by release of spring forces in the stranded elements  114  while cooling (i.e., binder film solidifies while outwardly stretched) such that the resulting cooled binder film  126  may not provide sufficient coupling force between the stranded elements  114  and central strength member  124  to prevent formation of a “bird cage,” resulting in bulges in the finished cable at the reversal points of the stranded elements  114 . When the core exits the caterpuller  320 , the core elements  114  are constrained from unwinding by the solidified binder film  126 . In contemplated embodiments, the caterpuller  320  may further be used for cooling (e.g., includes cooled belts) and/or may include a series of shaped rollers, such as having a groove along which the core  112  is constrained. 
     According to an exemplary embodiment, the binder film  126  maintains the integrity of the core  112  during subsequent processing steps, which may include tight bends of the cable  110 ,  210  and/or applications of additional cable components. In some embodiments, the binder film  126  has the additional advantageous feature of removal by initiating a tear (see  FIG. 12 ), such as with ripcords  142  positioned beneath the binder film  126  (see ripcords  142  above and below the binder film  126  as shown in  FIG. 1 ). The binder film  126  distributes the load from such ripcords  142  over a larger area of core elements  114  (when compared to ripcords beneath binder yarns), which reduces pressure on the core elements  114  during the tear. 
     Still referring to  FIGS. 4-6 , a method  310  of manufacturing a fiber optic cable  110 ,  210  includes steps of stranding core elements  114  about a central strength member  124 , forming a binder film  126  to surround the core elements  114  and to at least partially constrain the core elements  114 , constraining the core  112  while the binder film  126  solidifies and contracts, and/or extruding a jacket  134  of the cable  110 ,  210  to surround the binder film  126 . The jacket  134  may be thicker than the binder film  126 . The core elements  114  include a tube  116  surrounding at least one optical fiber  118 , and a plurality of additional core elements  114 , such as at least one of a filler rod  112  and an additional tube  116 ′. In some such embodiments, the binder film  126  includes (e.g., comprises, consists essentially of, consists of) a layer of material having a Young&#39;s modulus of 3 gigapascals (GPa) or less. In some such embodiments, the method  310  further includes steps of forming the binder film  126  so that the binder film  126  is 0.5 mm or less in thickness, and actively cooling the binder film  126 . As the binder film  126  cools, such as by a cooling flow of air, and the core  112  is supported by a caterpuller  320 , the binder film  126  shrinks around the core elements  114  to constrain the core elements  114  such that the core elements  114  are bound to the central strength member  124  under tension T of the binder film  126  and such that a coupling force (e.g., static frictional force) between the core elements  114  and the central strength member  124  limits axial and/or outward migration of the core elements  114  from the central strength member  124 . In some such embodiments, the method  310  further includes moving powder particles  132 ,  136  and directing the powder particles  132 ,  136  toward the binder film  126  and/or central strength member  124 , while the binder film  126  and/or up-jacket  130  is at least partially fluid (e.g., tacky). At least some of the powder particles  132 ,  136  are partially embedded in the binder film  126  and/or up jacket  130  upon cooling. 
     Such a manufacturing process  310  may remove a need for some or all binder yarns and water-blocking tape, described in the Background, and replace such components with a continuously-extruded binder film  126  that may have super-absorbent polymer particles  136  embedded in the interior surface of the binder film  126  and/or on the exterior surface of the binder film  126 . In addition, the binder film  126  may constrain the reversal of stranded core elements  114  in the radial direction. Rip cords  142 , material discontinuities  140 , or other access features may be integrated with the cable  110 ,  210 , such as being located outside of, in, or underneath the binder film  126  for either armored-type cable (see generally  FIG. 3 ) or duct-type cable (see generally  FIG. 1 ). 
     Referring again to  FIG. 4 , core elements  114 , in the form of the tubes  116  containing optical fibers  118 , are guided through an extrusion crosshead and tip by a stranding (oscillating) nose piece  312 . An extruded binder film  126  is applied to the core  112  immediately after the core  112  is formed by the oscillation of the nose piece  312 . Rotation of the stranded core  112  and central strength member  124  is limited by the anti-torsion caterpuller  320 . Further, the anti-torsion caterpuller  320  may serve to prevent unwinding during the reversal of the oscillation direction, allowing the binder film  126  to quickly cool and constrict to load the stranded elements  114  against the central strength member  124  such that there is sticking contact therebetween (e.g., static friction) that limits axial migration of the stranded elements  114 . 
     As shown in  FIG. 4 , the binder film  126  may be applied with no water-absorbent powder particles. In  FIG. 5 , the cable  110 ,  210  may be produced with an interior application but without an exterior application of water-absorbent powder particles  136 . In  FIG. 6 , water-absorbent powder particles  136  are applied to the interior and exterior of the extrudate cone of the binder film  126 . Residual powder particles may pass through gaps between the core elements  114  to the central strength member  124  where the powder particles may be captured by the tubes  116  and other interior surfaces of the core  112 . 
     Use of a binder film  126 , as disclosed herein, may permit continuous or near-continuous cable  110 ,  210  production, may eliminate binder yarn indentations on core elements  114 , may remove cable binding as a production speed constraint, may permit stranding to be speed matched with jacketing, may contribute to the strength of the jacket  134 , may replace water-blocking tape, may eliminate the associated tape inventory and the tape-width inventory subset, may allow access by ripcord  142  to the core elements  114  (where binder yarns generally cannot be cut by the ripcord, as discussed), may provide significant cost savings in materials, and/or may allow for removal of water-blocking yarn wrapped around the central strength member in some conventional cables. 
     In alternate contemplated embodiments of the above-disclosed cables  110 ,  210  and manufacturing methods  310  and equipment, a capstan may be used in place of the caterpuller  320 . In some embodiments, water-absorbent powder  136  may not be applied to the exterior of the binder film  126 , and a water bath may be used to increase the cooling rate. Further, the caterpuller  320  or at least a portion thereof may be submerged in the water bath. In some embodiments, water-absorbent powder  136  may not be applied to the interior surface of the binder film  126 , or to either the interior or the exterior surfaces of the binder film  126 . Thermoplastics and/or materials other than polyethylene may be used to form the binder film  126 . The binder film  126  may be of various colors, and may have UV stabilizers that permit the binder film  126  as the exterior of a finished outdoor product. The binder film  126  may be printed upon. The binder film  126  may include tear features  140 , such as those as disclosed herein with regard to the jacket  134 . In some embodiments, the binder film  126  may surround a broad range of different types of stranded cable components, such as S-Z stranded tight-buffered fibers, filler rods, fiberglass yarns, aramid yarns, and other components. 
       FIG. 7  shows a polypropylene extrusion cone  412  projecting from a crosshead  414  and drawing down over a core  416  of stranded elements during manufacturing of a cable  418 . As shown, the extrusion cone  412  draws down to a thickness of about 0.11 mm (or less) and the line speed is about 50 meters per minute (or faster) with a crosshead  414  temperature of about 210° C. According to an exemplary embodiment, the polypropylene of the extrusion cone  412  includes a nucleator to facilitate fast recrystallization of the polypropylene. For example, the polypropylene of the extrusion cone  412  is believe to recrystallize at a temperature at least 20° C. higher than high-density polyethylene, and with requiring roughly up to one-third less energy to extrude than high-density polyethylene. 
     Referring to  FIG. 8 , a stranded core  612  of a cable  610  extends from a jacket  614  of the cable  610 . The core  612  includes a reversal  616  in the strand direction, and the core  612  is bound by a binder film  126  as disclosed herein. The jacket  614  is polymeric (e.g., includes polyvinyl chloride, polyethylene, and/or other materials). According to an exemplary embodiment, the cable  610  includes a dielectric armor layer beneath the jacket  614 , between the jacket  614  and the core  612  (see also  FIG. 3 ). 
     Referring now to  FIG. 9 , a graphical representation via differential scanning calorimetry compares the heat flow of two different potential materials for the binder film  126 : high-density polyethylene (labeled “HDPE” in  FIG. 9 ; e.g., Dow 7590 HDPE natural pellet) and polypropylene (labeled “PP” in  FIG. 9 ; e.g., INEOS NO5U-00 PP natural pellet). The graphical representation shows that the polypropylene “melting point” is closer to (e.g., within 50° C.; within 30° C.) the processing/extrusion temperature (e.g., about 200-230° C.±20° C.), which is useful for quickly solidifying the binder film  126  (i.e., less change in temperature is required to achieve solidification after extrusion), such that the binder film  126  contracts while the stranded elements  114  are constrained by the caterpuller  320  so that the binder film  126  loads the stranded elements  114  in compression with the central strength member  124  providing a coupling force therebetween that prevents the formation of “bird cages.” 
     According to an exemplary embodiment, the material of the binder film  126  may be selected such that the melting temperature of the material of the binder film  126  is less (e.g., at least 30° C. less, at least 50° C. less) than the extrusion temperature (e.g., about 200-230° C.±20° C.) of a jacket  134  (see  FIG. 1 ) that is subsequently extruded over the binder film  126 . In some such embodiments, the binder film  126  melts or blends into the jacket  134 . In other embodiments, the binder film  126  maintains separation from the jacket  134  by intermediate material, such as super-absorbent polymer particles. Applicants theorize that a reason the stranded elements  114  do not migrate axially or outwardly during extrusion of the jacket  126 , while melting or softening of the binder film  126 , is that, by the time of subsequent extrusion of the jacket  126  (e.g., at least 2 seconds following stranding and application of the binder film  126 , at least 5 seconds, at least 10 minutes), the stranded elements  114  have sufficiently conformed to the geometry of the stranding pattern due to stress relaxation of the materials of the stranded elements  114 , reducing spring forces initially carried by the stranded elements  114  upon stranding; and Applicants theorize that the jacket  134  positively contributes to radial tension applied by the binder film  126  to constrain and normally load the core elements  114  to the central strength member  124 . 
     Further, Applicants have found that application of the binder film  126  at extrusion temperatures above the melting temperature of the stranded elements  114  (e.g., at least 30° C. above, at least 50° C. above) does not melt or substantially deform the stranded elements  114 . As such, the binder film  126  may include the same or similarly-melting polymers as buffer tubes  116 ,  116 ′ stranded in the core  112 , such as polypropylene. Further, Applicants have found very little or no sticking between the binder film  126  and buffer tubes  116 ,  116 ′ stranded in the core  112 , presumably due to the rapid cooling techniques disclosed herein, such as actively directing a flow of cooling air, caterpuller  320  in a water bath, thin film layer, binder film material selected for solidification/crystallization temperatures of the binder film  126  close to the extrusion temperature, and/or other techniques. 
     Further, the graphical representation in  FIG. 9  may be interpreted to predict the draw-down ratio of the extrudate material forming the binder film  126 . Applicants believe that the relationship is such that smaller the area under the curve, the higher the crystallinity and therefore the higher the required draw-down ratio. In general polyethylene is more crystalline than polypropylene, and high-density polyethylene is more crystalline than low-density polyethylene. 
     From a different perspective, the effectiveness of a material for the binder film  126  may be related to temperature of crystallization, at which crystals start growing and therefore mechanical properties start developing. It is Applicants&#39; understanding that the temperature of crystallization is around 140° C. for nucleated polypropylene (e.g., N05U-00), while the temperature of crystallization is at a lower temperature for high-density polyethylene (e.g., 7590), such as less than 125° C. Applicants theorize that materials that crystallize at higher temperatures will lock down faster and may work better for binder film  126  applications as disclosed herein (i.e. such materials apply more radial force to the core  112  earlier). 
     Further, it is Applicants&#39; understanding that, to some degree, draw-down of the materials continues until the glass-transition temperature is reached. In the case of polypropylene, glass-transition temperature may be reached about  − 10° C. and for polyethylene  − 70° C. (but may be as high as  − 30° C.). Accordingly, such low temperatures will not likely be reached in processing/manufacturing, so the binder film  126  may actively continue to shrink post-processing (until glass-transition temperatures are reached), which may further improve coupling between the stranded elements  114  and the central strength member  124 . For other possible binder film materials, such as polybutylene terephthalate, with a glass-transition temperature of about 50° C., the normal force applied to the stranded elements may be less because the binder film  126  may stop actively shrinking or having a bias to shrink. 
     Further, Applicants have found that the greater strength of polypropylene relative to polyethylene allows the binder film  126  to be thinner for a polypropylene binder film  126  to provide the same amount of coupling force between the stranded elements  114  and the central strength member  124 . For example, a 0.15 mm binder film  126  of polyethylene was found to have about a 70 N radial force, while a 0.15 mm binder film  126  of polypropylene had about an 85 N radial force. However, polyethylene is typically considerably less expensive than polypropylene, and in other embodiments, polyethylene may be used for the binder film  126 . 
     In some embodiments, the binder film  126  is formed from a first material and the jacket  134  is formed from a second material. The second material of the jacket  134  may include, such as primarily include (&gt;50% by weight), a first polymer such as polyethylene or polyvinyl chloride; and the first material of the binder film  126  may include, such as primarily include, a second polymer, such as polypropylene. In some embodiments, the first material further includes the first polymer (e.g., at least 2% by weight of the first material, at least 5% by weight, at least 10% by weight, and/or less than 50% by weight, such as less than 30% by weight). Inclusion of the first polymer in the first material of the binder film  126 , in addition to primarily including the second polymer in the first material, may facilitate bonding between the first and second materials so that the binder film  126  may be coupled to the jacket  134  and automatically removed from the core  112  when the jacket  134  is removed from the core  112 , such as at a mid-span access location. 
       FIGS. 10-11  show a sample  510  of a core  512  of stranded elements  114  within a binder film  126  that is configured for a pull-through test to determine the coupling force between the stranded elements  114  and the central strength member  124 . As shown in  FIG. 10 , the central strength member  124  extends from the stranded elements  114  by a distance of about 50 mm. 
     As shown in  FIG. 11 , the extended portion of the central strength element  124  is held fixed with a clamp  514 . A plate  516  with an opening just wide enough for the central strength member is attached to a tensile test apparatus  518  so that as the apparatus  518  lifts the plate  516 , and the plate  516  pushes the stranded elements  114  along the central strength member  124 . Applicants have found that the binder film  126 , as disclosed herein, results in a (net) static friction force between the stranded elements  114  and the central strength member  124  of at least 10 N for a 100 mm length of stranded elements, such as at least 15 N. 
     Via pull-through testing, Applicants have found that the magnitude of the static friction force is related to the thickness of the binder film  126 . For a polypropylene binder film  126  of at least 0.02 mm but less than 0.04 mm in average wall thickness, the static friction force for a 100 mm section of stranded elements  114  (without a jacket) is at least 10 N, such as about 12.4 N, and/or the average static friction force for a 200 mm section of stranded elements  114  is at least 20 N, such as about 23.1 N. Accordingly, for such a binder film  126 , the reverse-oscillatory stranding pattern must be such that the net spring force of the stranded elements  114  is about 10 N or less for a 100 mm section to prevent axial migration of the stranded elements  114  and formation of a “bird cage” during manufacturing. Applicants have also found, for a polypropylene binder film  126  of at least 0.08 mm but less than 0.15 mm in average wall thickness, the average static friction force for a 100 mm section of stranded elements is at least 20 N, such at least 30 N, and/or the average static friction force for a 200 mm section of stranded elements is at least 40 N, such as at least 50 N. Some testing included stranded elements bound by both binder film  126  and binders yarns to determine the contribution of the binder film  126 . 
     Referring to  FIGS. 12-13 , a stranded core  712  of a cable  710  includes a binder film  716  that constrains the stranded elements  718  having a reversal  714 . In some embodiments, the core  712  may be enclosed within a jacket (see  FIG. 8 ). As shown in  FIG. 13 , the binder film  716  is a thin polymeric material (e.g. polypropylene, polyethylene), which can be torn and peeled back by hand to provide access to the stranded elements  718  and central strength member  720 . Once released from the binder film  716 , the stranded elements  718  may decouple from the central strength member  720 , as shown in  FIG. 13 . Optical fibers  722  extend from the end of one of the stranded elements  718 , which is a buffer tube  724  (e.g., including polypropylene). The other stranded elements  718  in  FIG. 13  are “dummy” tubes or solid polymeric rods that fill positions in the strand. 
       FIGS. 14-15  show another advantage of the binder film  716  is that stranded elements  718  can be accessed by opening the binder film  716 , but without severing and/or removing lengthwise tension in the binder film  716 . As shown in  FIG. 14 , a lengthwise incision  726  is formed in the binder film  716 , which may be guided by an interstice (i.e., open space, gap, groove) between stranded elements  718 . Due to the thinness of the binder film  716 , the incision  726  can be made without specialize tools. For example, the incision  726  shown in  FIG. 14  was cut with scissors. A razor blade, key, pocket knife or other common tools may also work. 
     The lengthwise incision  726  provides an opening through which the stranded elements  718  can be unwound at a reversal  714  to provide extra length for handing the stranded elements  718 , and one or more of the elements  718  may be tapped at the mid-span location. For example,  FIG. 15  shows one of the elements  718  (buffer tube  724 ) has been cut and pulled out of the opening formed by the incision  726  so that optical fibers  728  of the element  718  can be accessed. At the same time, the rest of the binder film  716  holds together and maintains tension forward and rear of the incision  726  along the length of the cable  710 . Once access is no longer needed, the opening can be taped, shrink wrapped, or otherwise secured and resealed. By contrast, binder yarns may need to be fully severed to access the stranded elements, releasing tension in the binder yarns. 
     As mentioned above, the material of the binder film  716  may be selected so that the binder film  716  is at least partially translucent, as shown in  FIGS. 11-15 . For some embodiments, the jacket (e.g., jacket  614  as shown in  FIG. 8 ) may be pulled back or be otherwise removed, with the binder film  716  intact. A reversal point in the strand can be easily located through such a binder film  716 , which can then be accessed, as shown in  FIGS. 14-15 . 
     The buffer tubes  116 ,  724  disclosed herein may include polypropylene, polyvinyl chloride, polycarbonate, polybutylene terephthalate, and/or other polymers. Fillers, additives, and other components may be added to the polymers. In some embodiments, in addition to the optical fibers  728 , the buffer tubes  116 ,  724  are filled with a filling compound, such as a grease or petroleum-based gel. The filling compound water-blocks the buffer tubes  116 ,  724  and provides coupling between the optical fibers  728  and the buffer tubes  116 ,  724 . In other embodiments, the buffer tubes  116 ,  724  are “dry” and are free of filling compound, as discussed above. In such embodiments, the buffer tubes  116 ,  724  may be water-blocked by water-swellable powder, such as super-absorbent polymer, which may be impregnated in a yarn extending through the cavity of the buffer tubes  116 ,  724  and/or the powder may be mechanically attached to the interior of the buffer tube  116 ,  724 , as discussed above. 
     According to an exemplary embodiment, the buffer tubes  116 ,  724  have an outer diameter that is 3 millimeters or less, such as 2.5 millimeters or less, or even 2 millimeters or less. The buffer tubes  116 ,  724  may have an average wall thickness of at least 100 micrometers, such as at least 200 micrometers, and/or less than a millimeter. As the number of optical fibers  728  increases for the same size buffer tube  116 ,  724 , the freedom of the optical fibers  728  therein to bend and have excess optical fiber length decreases. Each buffer tube  116 ,  724  may include at least one optical fiber  728 , such as at least four optical fibers  728 , such as at least twelve optical fibers  728 . Dummy rods may replace one or more of the buffer tubes  116 ,  724 , as discussed above. 
     According to an exemplary embodiment, the optical fibers  728  include a glass core immediately surrounded by a glass cladding, which is immediately surrounded by one or more layers of a polymer coating, such as softer, stress-isolation layer of acrylate immediately surrounded by a harder shell of acrylate. According to an exemplary embodiment, the optical fibers  728  are individual, discrete optical fibers, as opposed to optical fibers of a fiber optic ribbon. In other embodiments, ribbons and/or stacks of ribbons are included. The optical fibers  728  may be single mode optical fibers, multi-mode optical fibers, multi-core optical fibers, plastic optical fibers, optical fibers having a uniform cladding, and/or other types. 
     The optical fibers  728  may be bend-resistant optical fibers having a cladding that includes annular layers of differing refractive indices or other types of bend-resistant optical fibers. An example of a bend-insensitive, or bend resistant, optical fiber is ClearCurve® Multimode fiber commercially available from Corning Incorporated of Corning, N.Y. In some such embodiments, when bent into a coil having a single turn with a diameter of about 200 millimeters, the optical fibers  728  have a change in optical attenuation (delta attenuation) at 1310 nanometers of about 0.1 dB or less per turn, and more preferably about 0.03 dB or less per turn, where the above delta attenuation is observed at one or wavelengths preferably greater than or equal to 1500 nm, in some embodiments also greater than about 1310 nm, in other embodiments also greater than 1260 nm. Use of bend-resistive optical fibers may facilitate improved optical performance of the associated cable, such as when the cable is stretched. 
     Lay length of the stranded buffer tubes  116 ,  724  is discussed above. In some embodiments, the lay length is particularly short, such as less than 1 meter along the length of the respective cable between reversals in a reverse oscillatory stranding pattern, such as less than 750 mm, such as less than even 500 mm in some embodiments. Between the reversals in at least some such stranded arrangement, the buffer tubes  116 ,  724  include at least 2 full turns (i.e. complete spirals) around the central axis of the strand, such as at least 3 full turns, and/or eve at least 4 full turns. The tightness of the stranding pattern relates to the loading required by the respective binder film  126 ,  716 . In general, tighter the lay pattern, the greater the torsional loading of the buffer tube  116 ,  716  away from the central axis of the strand (e.g., central strength member) at the reversals. For example, embodiments disclosed herein may achieve the above-described coupling to the central strength member while undergoing such tight lay patterns. 
     In contemplated embodiments, the above-described manufacturing methods, equipment (and arrangements thereof), and processes may be used to extrude a thick film over a stranded core, instead of a thin film, where thick film may function similar to a cable jacket, such as being the outermost layer of the respective cable. For example, such a cable may include a thick film having a thickness of greater than 1 mm, such as at least 1 mm. The above-described processes may be used if the line speed is reduced, if the caterpuller or other constraining device is further lengthened, if additional active cooling is used, if the material is selected and/or extruded to rapidly solidify following extrusion, or other processes are used. As such, the films disclosed herein are not limited to particularly thin films, unless expressly limited as such in the claims. 
     Referring to  FIG. 16 , a fiber optic cable  910  includes core elements  912 , such as inner core elements  914 , wound in a pattern of stranding. The inner core elements  914  may include at least two, at least four, at least six core elements  912  such as buffer tubes, micromodules, electrical conductors, tight-buffered fibers, and/or other components. In some embodiments, the pattern of stranding is helical. In other embodiments, the pattern of stranding includes reversals in the lay direction of the stranded elements, such as so-called SZ stranding or continuous-reversal stranding. In some embodiments, tubes of the inner core elements  914  surround optical fibers  916 . 
     According to an exemplary embodiment, the fiber optic cable  910  further includes an inner binder film  918 , similar in structure, function, and composition to other binder films disclosed herein. The inner binder film  918  is surrounding the stranded inner core elements  914 . According to an exemplary embodiment, the inner binder film  918  is continuous peripherally around the core elements  912 , forming a continuous closed loop when viewed in cross-section. The inner binder film  918  is also continuous lengthwise along a length of the cable  910  that is at least a meter, such as at least 5 meters, at least 10 meters, etc. At some or all times, the inner binder film  918  is in radial tension and opposes outwardly transverse deflection of the inner core elements  914 , similar to other binder films disclosed herein. 
     According to an exemplary embodiment, the fiber optic cable  910  further includes outer core elements  920  wound in a pattern of stranding around the inner binder film  918  and the inner core elements  914 . In some embodiments, the outer core elements  920  are similar in structure, function, and composition to the inner core elements  914 , and may likewise include tubes surrounding optical fibers  916 . In some embodiments, the outer core elements  920  include more core elements  912  than the inner core elements  914 , such as a total of at least 5, at least 8, and/or at least 10 outer core elements  920 . The fiber optic cable  910  may further include an outer binder film  922  surrounding the stranded outer core elements  920 . Accordingly, the inner binder film  918  and inner core elements  914  are nested within the outer core elements  920 , and the outer core elements  920  are, in turn, nested within the outer binder film  922 , as shown in  FIG. 16 . 
     The outer binder film  922  may be surrounded by armor (see generally armor  138 ) in some embodiments. In other embodiments, the outer binder film  922  is bonded directly to a jacket  924  exterior thereto, such as cohesively bonded by common materials in both the jacket  924  and the outer binder film  922 . In contemplated embodiments, a similar such cable  910  may include additional layers of stranded core elements  912 , such as a third, fourth, and/or fifth level of stranded core elements  912 , each level bound by a binder film as disclosed herein. According to an exemplary embodiment, the fiber optic cable  910  further includes a jacket  924  surrounding the outer binder film  922 . In some embodiments, the inner and/or outer binder film  918 ,  922  is thinner than the jacket  924 , such as having a thickness of 0.5 millimeters or less, where the jacket  924  is at least five times thicker than either the inner binder film  918  or the outer binder film  922 . 
     Similar to other loose tube cables disclosed herein (see generally  FIG. 1 ), the fiber optic cable  910  may further include a central strength member  926 , where the inner core elements  914  are stranded around the central strength member  926 . In some such embodiments, the inner binder film  918  loads the inner core elements  914  normally to the central strength member  926  such that contact between the inner core elements  914  and central strength member  926  provides coupling therebetween, which limits axial migration of the inner core elements  914  relative to the central strength member  926 , such as due to the pull of the corresponding extrusion cone, as discussed above. In some embodiments, the pattern of stranding of the inner core elements  914  includes reversals in lay direction of the inner core elements  914 , and the pattern of stranding of the outer core elements  920  also includes reversals in lay direction of the outer core elements  920 . 
     Still referring to  FIG. 16 , and generally referring to  FIGS. 4-6 , in some embodiments the fiber optic cable  910  further includes water-swellable powder attached to the inner binder film  918  and/or the outer binder film  922 . In some embodiments, the water-swellable powder is attached to the exterior  928  of the inner binder film  918  such that at least some of the water-swellable powder is positioned between the inner binder film  918  and the outer core elements  920 . Such positioning may be counter-intuitive to cable designers because water-swellable powder exterior the extruded component (e.g., inner binder film  918 ) may swell if exposed to water, such as water in the air or water in a cooling water trough. However, in some embodiments the inner binder film  918  cools quickly enough without cooling water trough, and the additional outer core elements  920  and outer binder film  922  may be applied before much water from the air is captured by the water-swellable powder. The water-swellable powder may be applied to the inner and/or outer binder films  918 ,  922  via the techniques disclosed herein, such as those processes shown in  FIGS. 4-6 . 
     In some embodiments, the fiber optic cable  910  additionally or alternatively includes additional water-swellable powder attached to the inner binder film  918  such that at least some of the powder particles thereof are positioned on an inside surface  932  of the inner binder film  918  between the inner binder film  918  and the inner core elements  914 . The outer binder film  922  may likewise include water-swellable powder attached an inside surface  934  of the outer binder film  922  between the outer binder film  922  and the outer core elements  920 . Accordingly, the outer binder film  922  may differ from the inner binder film  918  at least with respect to presence and/or positioning of water-swellable powder attached thereto. For example, the inner binder film  918  may include powder attached to both sides  928 ,  932 , while the outer binder film  922  may only include powder attached to one side  934  thereof, with the other side thereof attached directly to the jacket  924 . The amount and composition of the water-swellable powder on surfaces of sides  928 ,  932 ,  934  may be similar or the same as quantities disclosed for other embodiments herein. 
     Referring now to  FIGS. 1 and 3  in general, once deployed to the field, cores of fiber optic cables may have to be accessed at an end- and/or mid-span location in order to gain access to the optical fibers, such as for splicing on tethers for fiber-to-the-home applications or other applications. The jacket and/or armor may be removed by accessing a conventional ripcord(s) that has been inserted longitudinally under the armor or other elements during manufacture of the respective cable. Conventional ripcords are typically made of polyester or aramid yarns that are of sufficient strength to shear the materials surrounding the cable core, such as the jacket and/or the armor, when the ripcords are pulled outwardly by a craftsman. Once the core is exposed with conventional cables, conventional binders (not shown in  FIGS. 1 and 3 ; not present in some embodiments; e.g., counter-helically wrapped polyester yarns) are removed by clipping them with seam rippers or scissors. Typically a ripcord is not used under conventional binders because pulling the ripcord could concentrate the binders on the core elements, inducing a concentrated load on buffer tubes, for example, or other core elements, which may cause damage to the core elements and/or optical fibers integrated therewith. 
     The presently disclosed technology includes use of an extruded film, such as binder films  918 ,  922 , to retain the strand of the buffer tubes or other core elements  912 . Use of a continuous binder film, as with various embodiments disclosed herein, facilitates use of a ripcord under the binder (i.e., continuous binder film) without the adverse effects described above because the binder more evenly distributes the load of the ripcord onto the buffer tubes or other core elements as the ripcord shears through binder. As such, some embodiments include a binder, such as binder films as disclosed herein, with a conventional ripcord beneath the binder, such as between the respective binder and core elements bound by the binder film. 
     In other embodiments, a ripcord-type feature  936  may be attached to the binder film  918  (or other binder films disclosed herein) such that the binder film  918  may be torn open via the ripcord-type feature  936 , such as by drawing thereupon. The ripcord-type feature  936  may be extruded into the binder film  918  and/or co-extruded therewith. In some embodiments, the ripcord-type feature  936  creates a preferential tear location within the binder film  918 . In some such embodiments, contrary to V-groove tear features and material discontinuity tear features that may be associated with cable jackets, ripcord-type features  936  disclosed herein may be formed without lessening the strength of the associated tube (e.g., binder film  918 ). Further, unique to the integrated ripcord-type feature  936 , is that the ripcord-type feature  936  is positioned generally on the outside of the surface  928  to be ripped, as opposed to embedded in or beneath the respective surface in some embodiments, as shown in  FIG. 17 , which may be counter-intuitive to cable designers and may be beneficial by being positioned further from optical fibers in the core and thereby potentially causing less micro-bending attenuation. 
     Referring to  FIG. 17 , a ripcord-type feature  936  may be continuously extruded during the extrusion of the binder film  918 . In some such embodiments, a greater concentration of material of the binder film  918  is extruded to form the ripcord-type feature  936 . Accordingly the ripcord-type feature  936  has more strength than the remainder of the binder film  918 . By pulling on the ripcord-type feature  936 , tearing of the binder film  918  occurs at, or near the location of the ripcord-type feature  936 . Similar to how a conventional ripcord may perform, the ripcord-type feature  936  may give fast and consistent access to the core elements  912  under the binder film  918 . 
     According to an exemplary embodiment, at least one position around the perimeter of the binder film  918  is extruded to a greater thickness than the remainder of the perimeter. The ripcord-type feature  936  may have a thickness T 2  that is at least twice a thickness T 1  of the binder film  918 , and may be of various geometries such as the rounded bump shown in  FIG. 17 . The ripcord-type feature  936  may be grasped with pliers or fingers and pulled causing a tear of the binder film  918  at or near a base of the extruded ripcord-type feature  936 . In some embodiments, the ripcord-type feature  936  has a product of modulus and cross-sectional area (EA) thereof that is greater than twice the EA of adjoining the binder film  918  of equal perimeter length T 3  on either side thereof. According to an exemplary embodiment, the ripcord-type feature  326  may be large enough to be easily identifiable by the tradesperson accessing the cable  910 , such as having a tangential dimension T 3  of at least 0.5 mm, such as at least 0.8 mm or even at least 1 mm in some embodiments. 
     Advantages of the ripcord-type feature  936  include that, in some embodiments, the ripcord-type feature  936  (1) allows rapid access to the core elements (e.g., buffer tubes); (2) eliminates or reduces a need for additional ripcord materials, equipment, and processes; (3) if extruded, may be continuous and may reduce or eliminate a need for splicing ripcord materials; (4) may be formed from extruded material that may be cheaper than conventional polyester or aramid ripcords; (5) may be operated with basic hand tools such as pliers; (6) may reduce or eliminate a need for sharp blades for cable core access; and/or (7) may not weaken the strength of the binder film  918 . 
     In some embodiments, the ripcord-type feature  936  may be a different color than the binder film  918  and/or jacket  924 , such as for easy visual identification of the ripcord-type feature  936 . In alternate embodiments, technology disclosed herein, such as the binder films and ripcord-type features, may be used in conductive cables of similar configurations to those described herein, or with hybrid conductor and fiber optic cables. In alternate embodiments, the ripcord technology disclosed herein could be used with cable jackets, such as those of indoor cables, micro-module cables, blown minicables, and/or duct cables, to facilitate access to cores thereof. The ripcord-type feature  936  may include, such as primarily include, any thermoplastic used for binder films disclosed herein, such as polypropylene, polyethylene, polyvinyl chloride, polyester, and/or nylon, or other materials. 
     Referring now to  FIG. 18 , in some embodiments a cable and/or bound cable core  1110  may include a binder film  1112  having a ripcord-type feature  1114  similar to the ripcord-type feature  936 , but the ripcord-type feature  1114  may instead include a folded or crimped section of the binder film  1112 . Folding the binder film  1112  may provide a segment of increased strength, and folding may also provide a localized stress concentration at the base  1116  of the ripcord-type feature  1114  to facilitate tearing open the binder film  1112 . Additionally, the ripcord-type feature  1114  may extend generally away from the exterior perimeter  1118  of the bound cable core  1110  in some embodiments, and may extend a distance D 1  such that the ripcord-type feature  1114  may be gripped by finger tips and/or pliers, such as the distance D 1  being at least 1 mm, such as at least 2 mm, and/or even at least 4 mm. Pinching, crimping, and/or folding the binder film  1112  to form the ripcord-type feature  1114  may occur along a manufacturing line, such as just prior to jacketing, particularly if the material of the binder film  1112  is stretchable/elastic, as disclosed above. The folded binder film  112  may be spot or laser welded at the base  1114  thereof to hold the ripcord-type feature  1114 . 
     Referring to  FIG. 19 , in some embodiments a cable  1210  and/or bound cable core  1210  may include a binder film  1212  having ripcord-type feature may include extruded polymeric (e.g., thermoplastic) ripcords  1214  in the form of solid polymeric strips or cords, which may be coupled directly to the binder film  1212  and/or may be positioned beneath the binder film  1212 , similar to conventional ripcords. Extruded polymeric ripcords in general may be counter-intuitive to cable designers because extruded polymers (e.g., thermoplastics, polyethylene, polypropylene, polyamide) may not be viewed as materials that are strong enough to tear through a jacket or armor. However, polymeric ripcords  1214  for binder films  1212  disclosed herein may have much less of a cutting burden. According to an exemplary embodiment, such ripcord-type features may be formed from a thermoplastic that is tougher/stronger that material of the corresponding binder film  1212 , such as in terms of EA as disclosed above (e.g., greater EA, at least twice the EA) than the corresponding binder film wall, and thereby able to tear open the binder film  1212  when pulled. The polymeric ripcords  1214  may be formed from the same material as the binder film, other extrudable polymeric materials disclosed herein, and/or thermoplastics and/or polymers. The polymeric ripcords  1214  may be co-extruded with the binder film  1212  and bonded therewith, such as cohesively bonded therewith. Alternatively, the polymeric ripcords  1214  may be extruded in tandem with the binder film  1212 , such as before the binder film  1212  is extruded on the manufacturing line (see generally ripcord  142  as shown in  FIGS. 4-6 ). As with any of the ripcord-type features disclosed herein, the fiber optic cable may include multiple such features beneath the binder film(s), such as two positioned about 180-degrees from one another, such as three that are spaced apart from one another by at least 30-degrees, or other numbers and/or arrangements of ripcord-type features. 
     The construction and arrangements of the cables, as shown in the various exemplary embodiments, are illustrative only. Although only a few embodiments have been described in detail in this disclosure, many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes, and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations) without materially departing from the novel teachings and advantages of the subject matter described herein. For example, in some embodiments, cables include multiple layers or levels of core elements stranded around a central strength member  124 , where each layer includes a binder film  126  constraining the respective layer and where binder film  126  of the outer layer(s) indirectly surrounds the binder film  126  of the inner layer(s). In contemplated embodiments, the binder film  126  is not extruded, but is formed from laser-welded tape and/or a heat shrink material, for example. Some elements shown as integrally formed may be constructed of multiple parts or elements, the position of elements may be reversed or otherwise varied, and the nature or number of discrete elements or positions may be altered or varied. In some contemplated embodiments, the binder film  126  with water-blocking powder, as disclosed herein, may function as an extruded water-blocking element, thereby allowing for continuous cable manufacturing without replacing reels of the water-blocking tape; which, for example, may block water between armor (or other outer layers in a cable  210 ) and a core  112 , such as a core of stacked fiber optic ribbons or a mono-tube core, or between other components in a cable. The order or sequence of any process, logical algorithm, or method steps may be varied or re-sequenced according to alternative embodiments. Other substitutions, modifications, changes and omissions may also be made in the design, operating conditions and arrangement of the various exemplary embodiments without departing from the scope of the present inventive technology.