bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Screw Stagger on Mixing in a Tangential Counter-Rotating Twin Screw Extruder
Authors: Bigio D. , Erwin L. 
Published: December 2013

Abstract
The Counter-Rotating, Tangential Twin Screw Extruder (CR TSE) is a polymer processing device which has been in industrial use for dozens of years. Over this period of time, many of the design parameters have been studied for their effect on processing issues that are related to a particular application. Recent studies have shown that the CR TSE is a greater-than-linear mixer and that is due primarily to the flow in the nip region. This study seeks to determine the relationship between mixing rates and percent of screw stagger. Using a flow visualization technique of an acid-dyeeradication, experiments were conducted varying the stagger setting every 10%. In this experiment the total mixing length was used as the measure of mixing. Data was taken at the time of the experiment and the process was videotaped for later review and data evaluation. The technique provides both qualitative and quantitative information. A discussion of the nature of the extruder performance as a function of screw stagger is reported and important design considerations presented.
Optimization of Cooling Systems for Injection Molding
Authors: Pandelidis I. O. , Lingard T. J. 
Published: December 2013

Abstract
An optimization methodology has been developed for the design of injection molding cooling systems. The cooling system design problem has been decomposed to determine the independent and dependent variables of the process and system design. The design goals were quantified and optimal solutions obtained by using numerical optimization techniques. A gradient driven solution method was implemented to perform the optimization task. Several complex molding examples were analyzed and significant improvements in cooling system performance were realized. Both quality and productivity concerns are addressed by the methodology. Commercial mold filling and cooling software are integrated with the optimization code to perform the cooling system analysis.
State of Dispersion – Mechanical Properties Correlation in Small Particle Filled Polymer Composites
Authors: Suetsugu Y. 
Published: December 2013

Abstract
Correlation between state of dispersion and mechanical properties is obtained and failure mechanisms from falling weight impact tests are discussed. The state of dispersion is characterized for calcium carbonate filled polypropylene model composites by using a scanning electron microscope. A dispersion index is defined in terms of the fraction of agglomerates of the filler remained in the composites. Improvement of dispersion uplifts tensile strength and more prominently falling weight impact strength. It is pointed out that an initial failure in the falling weight impact test rises at the agglomerate existing near the loading point. Falling weight impact strength is found to be dependent upon the distance from loading point to failure initiation point where the agglomerate exists. This explains the dependency of impact strength on the state of dispersion and a large sample deviation often observed in the falling weight impact test.
Innovative Extrusion Systems for Advanced Fiber and Film Extrusion
Authors: Hensen F. 
Published: December 2013

Abstract
Advanced fiber and film extrusion is a term used to describe high speed spinning of low denier filaments and stretching of thin films at high output rates and high efficiencies. Using the advantages of separated process steps, extrusion systems have been developed in which the main process steps, such as feeding, melting, homogenizing, filtering, mixing and metering, take place in special separate equipment aggregates. In comparison to standard extruders with combined process steps, these extrusion systems give better melt quality as measured by the uniformity of melt flow, drawability of the fibers or films and the dispersion of additives. Examples of extrusion systems for PET or PP with appropriate operating conditions and output rates are described. The different applications of these systems and their main details are listed in a survey.
Melt Strength Behavior of PE and its Relation to Bubble Stability in Film Blowing**
Authors: Ghijsels A. , Ente J. J. S. M. , Raadsen J. 
Published: December 2013

Abstract
Melt strength data are presented on the three major classes of commercial polyethylenes (LDPE, LLDPE and HDPE). The LDPE samples studied were polymerised by both tubular and autoclave reactor technology and the LLDPE samples were produced with different α-olefins as comonomer. Melt strength was assessed from uniaxial tensile experiments with a Rheotens apparatus. The melt strengths of both LLDPEs and HDPEs are much lower than those of LDPEs when compared at equal melt index or zero-shear viscosity level. Among the LDPEs the highest melt strength is observed for the LDPEs made by autoclave technology. The type of comonomer present in LLDPEs does not significantly affect its melt strength. The molecular factors controlling the melt strength of pure polyethylenes are discussed. A high melt strength is identified with a good bubble stability in the film blowing process.
Dynamics of Double Bubble Tabular Film Process for Producing Biaxially oriented Nylon 6 Film
Authors: Takashige M. , Kanai T. 
Published: December 2013

Abstract
A double bubble tubular film process for nylon 6 was investigated. This report discussed three topics: Relationship between process conditions and film stretching stresses; deformation rate during double bubble process, birefringence and film thickness uniformity; and scale-up rule for double bubble tubular film process. The optimum stretching stress during the double bubble tubular film process exists. The bubble break occurs over stress of 1300 Kg/cm2 and bubble stability occurs below stress of 600 Kg/cm2. The cross point of stretching stress, which means stress in the machine direction is equal to stress in the transverse direction, is influenced by a deformation rate which is closely related to birefringence and bubble stability. Bubble stability and film thickness uniformity are improved with increasing deformation rate. It is found that the scale-up rule which was set up theoretically is applicable to predict the physical properties and bubble stability for large scale double bubble tubular film process once the same process is carried out by using the same scale machine and a small amount of resin.
A Finite Difference Study of Roll Design in Calendering Processing
Authors: Tseng A. A. , Sun P. F. 
Published: December 2013

Abstract
A numerical model has been developed to simulate the polymeric flow and heat transfer in calendering processing. In the flow calculation, the polymer is treated as a thermal-dependent power-law fluids; in the coupled heat transfer calculation, both the roll and the polymer are modeled in order to assess the performance of various designs of calendering rolls. The numerical predictions agree very well with the on-line measurements. The generalized finite difference scheme was selected to cope with the numerical difficulties involved in the modeling of the process, especially the curved boundary and the free surface conditions. The computational aspects of the finite difference scheme in modeling of polymer behavior are also discussed.
Relationship between Rotor Designs in an Internal Mixer and Physical Properties of Mixed Rubber Compounds
Authors: Kawanishi K. , Yagii K. , Obata Y. , Kimura S. 
Published: December 2013

Abstract
Internal mixers are commonly used for rubber compounding in industry. However, the relations among the designs of equipments, mixing conditions and the properties of the resulting compound are little known. In this paper we tried to reveal some manners of the relations concentrating, particularly, on rotor designs. A specially designed internal mixer (Banbury type) was developed. A number of double winged rotors of various shapes and replaceable mixing chambers were prepared. In developing the equipment, eight parameters were taken into consideration concerning the shape of rotors, that is, lengths, twist angles and overlap ratio of the wings, width and clearance at the rotor tip, angles of flow-in and flow-out at the gap area and total bulkiness of the rotor. Measured properties concerning mixing are: unit work, Mooney viscosity of dumped compound, the amount of bound rubber, weight average molecular weight of the extracted portion of the compound, and peaks in a torque curve, i.e., values of first peak torque and second peak time. In order to estimate the degree of influences of the design parameters mentioned above and mixing conditions, each measured properties were expressed as functions of these parameters by means of multiple regression analysis.
Feed Variance Limitations for Co-rotating Intermeshing Twin Screw Extruders
Authors: Curry J. , Kiani A. , Dreiblatt A. 
Published: December 2013

Abstract
The extent of feeder error to survive a plasticating compounding extruder is addressed in this theoretical and experimental study. Results of unit step and cyclic variation of tracer concentration were used to define the transfer function and damping ratio respectively. The frequency dependent damping ratio of cyclically varying tracer content in the feedstream was predicted for three screw configurations with fair agreement to experiment.
A Stick-Slip Problem Related to Melt Fracture in Polymer Processing Operations
Authors: Adewale K. E. P. , Olabisi O. , Oyediran A. A. , Olunloyo V. O. S. 
Published: December 2013

Abstract
A ‘Stick-Slip’ mixed-boundary model is postulated to support the mechanism of transition from no-slip to slip at the polymer/die interface during capillary extrusion of polymeric materials at and above a critical shear rate at a fixed throughput. The predicted shear stress singularity explains the occurence of gross extrudate distortion known as melt fracture.
Effects of Plasticizers on Extrusion of Dry Blended PVC
Authors: Datta A. , Baird D. G. 
Published: December 2013

Abstract
This research was concerned with the effect of two different plasticizers on the plasticating extrusion behavior of polyvinylchloride (PVC). Diisodecyl pthalate (DIDP) and dihexyl pthalate (DHP) were the the two plasticizers used in this study. First some differences in the extrusion performance of the two differently plasticized PVC compounds were identified. In particular, it was observed that pressure build-up and power requirement were affected by the plasticizer type with the DIDP plasticized materials generating higher pressures and requiring more power than the DHP plasticized materials. Also the DIDP plasticized material fused earlier in the screw channel and in general exhibited slightly higher flow rates. The differences in extrusion characteristics were observed for two different dies attached to the extruder.
Pressure Oscillations during Capillary Extrusion of High Density Polyethylene
Authors: Becker J. , Bengtsson P. , Klason C. , Kubát J. , Sáha P. 
Published: December 2013

Abstract
This paper demonstrates the usefulness of frequency analysis in monitoring melt flow instabilities. The flow behavior of a film-blowing grade of high density polyethylene has been studied using a capillary rheometer at constant piston velocities. The pressure in the reservoir was measured by a transducer fitted to the driving end of the piston. The signal was amplified and processed in a Fast Fourier Transform (FFT) frequency analyzer. The pressure fluctuations (noise) have a very low intensity at low flow rates in the sharkskin region. The noise signal increases dramatically at a critical shear stress of about 1.5 × 105 Pa, where the flow assumes a pulsating character (spurt defect). Above the pressure oscillation region the melt goes through a pseudostable region, followed by a secondary pressure oscillation region, eventually reaching a chaotic stage. The noise spectrum intensity seems to be related to the severity of the surface disturbances of the extrudate in this latter branch of the flow curve.
Biaxially-oriented Polyethylene Films by Compression of Injected Moldings
Authors: Ania F. , Bayer R. K. , Baltà Calleja F. J. 
Published: December 2013

Abstract
Biaxially oriented PE films were prepared by compression of uniaxially oriented elongational-flow injection-molded precursors. The films so prepared, having different extents of biaxial stretching were compared on the basis of two derived functions, biaxial draw ratio (ƛ) and degree of biaxiality (B). The former gives a quantitative measure of the average draw ratio of the film surface. The latter describes the strain distribution along the principal directions of the film plane. It is shown that ƛ and B depend on the final applied pressure and on the type of pressing surfaces used. The dependence of ƛ and B on the initial orientation and on the initial anisometry of the precursors is also discussed in the light of structural arguments.
Dynamics and Stability of Double Bubble Tubular Film Extrusion
Authors: Kang H. J. , White J. L. 
Published: December 2013

Abstract
A basic study of the kinematics and dynamics of the double bubble tubular film process as applied to polyethylene terephthalate (PET), poly p phenylene sulfide (PPS), polycarbonate (PC) and low density polyethylene (LDPE) is presented. The stability of the four resins was investigated for both a single bubble tubular film and a second bubble of a double bubble process. For the single bubble the LDPE is very stable and the PET, PPS and PC have more limited regions of stability with periodic axisymmetric instabilities near blowup ratios of unity and helical instabilities at higher blowup ratios. It is found that in the first bubble the PC vitrifies to a glass, PET and PPS crystallize to 4 to 9% levels and LDPE to nearly 50%. In the second bubble it is found possible to operate in a stable manner with a heated air ring and stable bubble for PET and PPS but not PC and LDPE. In the second bubble PET and PPS show substantial levels of increase of crystallinity. This is not the case for PC and LDPE. It appears that a strain hardening process such as crystallization is necessary for stability of the second bubble. Stress fields in the second bubble are computed using membrane theory.
Issues Concerning the Rate of Heat Transfer from a Spinline
Authors: Vassilatos G. , Schmelzer E. R. , Denn M. M. 
Published: December 2013

Abstract
Two-dimensional convective heat transfer in a non-isothermal spinline is analyzed. A rigorous derivation of the macroscopic, one-dimensional energy balance describing the cooling of a spinline leads to an equation that differs subtly from the commonly used one-dimensional equation; this difference has practical implications for the correct computation of convective heat transfer coefficients from experimental data obtained from spinlines exhibiting significant radial temperature gradients and, in turn, for the prediction of correct spinline temperature profiles. The errors involved are illustrated with computed results and a method is proposed for the determination of the correct heat transfer coefficients in the presence of radial temperature gradients. Further, it is shown that the radial convective heat flux resulting from the inward radial velocity of an attenuating spinline is important and its omission can lead to significant errors in the computed temperature.
Molecular Orientation in Injection-Molded Polypropylene Copolymers with Ethylene
Authors: Fujiyama M. , Wakino T. 
Published: December 2013

Abstract
The molecular orientation process in injection molding of polypropylene copolymers with ethylene was theoretically analyzed from a view point of growth of melt orientation (recoverable shear strain) at the gate and its relaxation in the mold cavity. Regardless of the characteristics of raw resin (copolymerization type and ethylene content) and molding conditions (cylinder temperature), there exist unitary correlations between calculated degree of molecular orientation and experimentally measured degrees of molecular orientation such as the thickness of skin layer and crystalline c-axis orientation function. According to this analysis, the fact that molecular orientation is decreased by copolymerization with ethylene is due to decrease in melt orientation (recoverable shear strain), decrease in the relaxation time and reduction of crystallization temperature.
Processing Characteristics of Thermoplastic Sheet Composites
Authors: Bigg D. M. 
Published: December 2013

Abstract
While there are several alternatives for producing thermoplastic sheet composites, only two have the characteristics needed for large scale manufacturing; continuous melt impregnation, and deposition of a polymer-impregnated, fiber-dispersed mat from an aqueous slurry. The most important factor affecting the melt impregnation process was found to be the rate of penetration of the molten polymer into the fiber structure. While Darcy's Law, using the Kozeny-Carmen permeation coefficient, provides an initial estimate of penetration rate, it does not adequately consider the slow flow around closely spaced fibers. The slurry deposition process incorporates the polymer directly within the fiber structure, and is not flow rate limited. The most important parameter affecting the consolidation of slurry formed mats was found to be the rate of heat transfer prior to consolidation. In both processes the time of contact between the molten polymer and glass fiber was shown to be important to the development of good adhesion.
Compounding of Thermoplastic Elastomers using Organosilanes
Authors: Anderlik R. , Fritz H.-G. 
Published: December 2013

Abstract
To enhance the material properties of polypropylene/rubber blends the rubber phase is crosslinked. In this study an organosilane crosslinking system is used which creates stable Si-O-Si bonds between the rubber chains and produces a polyfunctional network structure with a high crosslinking density. This organosilane system allows in principle to prepare blends which are statically or dynamically crosslinked. Results concerning the morphology of blends prepared under different compounding parameters are presented. Particular attention was directed to the interrelationship of rheological properties of the blend components and the morphological structure of the created blends. In the closing chapter of this paper the material properties of blends, including EPM or EPDM in a silane-crosslinked mode are compared with those of only physically mixed PP/EPDM-blends.
Microstructure Formation in Extruded and Drawn Polyblends of PC with a Thermotropic LCP
Authors: He J. , Bu W. , Zhang H. , Xie P. , Xu X. 
Published: December 2013

Abstract
Melt blending, extrusion and drawing of polycarbonate (PC) blends containing a thermotropic liquid crystalline polymer (LCP) are reported for a copolyester PCDT synthesised in this laboratory. A single screw extruder is used at four temperatures. The rheology of the PCDT/PC blend, PCDT and PC was measured by means of a capillary rheometer at these temperatures. The morphology of extruded and subsequently drawn strands was studied with the help of a scanning electron microscope and analysed. In PCDT/PC extruded strands, the morphology of the PCDT dispersed phase, changes from spherical through ellipsoidal to elongated with decreasing processing temperature. In contrast to this, in drawn strands with a draw ratio of 10, the morphology of the PCDT changes from ellipsoidal through elongated to fibrillar with increasing processing temperature. It is believed that the relative viscosity of the two phases is the decisive factor determining the microstructure formation of polymer blends containing thermotropic liquid crystalline polymers. Fibril formation is related to the deformation and coalescence of PCDT melt droplets by the drawing at higher temperatures.
Effect of Biaxial Stretching on Mechanical Properties and Surface Roughness of PMMA Films
Authors: Wang Y. D. , Cakmak M. 
Published: December 2013

Abstract
Recently the use of PMMA films as the top layer of dish membrane solar collectors has gathered popularity. The mechanical properties and surface smoothness of PMMA films are the important factors affecting the durability and optical performance of these stretched membrane solar collectors. In this paper, we present the results of our experimental study on the effect of biaxial stretching on mechanical properties and surface roughness of PMMA films. Biaxial stretching was found to improve both the mechanical properties and surface smoothness of PMMA films.
Detailed Investigations of Structural Layering Phenomena in Injection Molded Thermotropic Liquid Crystalline Polymers
Authors: Hsiung C. M. , Cakmak M. 
Published: December 2013

Abstract
The structural gradients developed in the injection molding of thermotropic wholly aromatic copolyester parts were characterized using a specially developed micro-beam wide angle X-ray diffraction camera technique and wide angle X-ray pole figure analysis techniques.
Wide angle X-ray pole figure analyses indicate that the local macro-symmetry throughout the sample seems to he uniaxial. The polymer chains are generally oriented in the flow direction except in the core regions after the diverging section, where molecular chains tended to orient transversely to the flow direction.
The local orientation of chains is determined from the micro-WAXS film patterns using DIA (Digital Image Analysis) technique. This enabled us to map the orientation of the local symmetry axes as well as local chain orientation through the thickness direction. The data indicate that the chain orientation is highest at the skin layer, becomes lower at the sub-skin layer, then increases gradually toward the shear layer and finally decreases to very low levels in the core regions.
Flow and Heat Transfer Simulation of the Mixing of Polymer Blends Using the Boundary Element Method
Authors: Gramann P. J. , Stradins L. , Osswald T. A. 
Published: December 2013

Abstract
In most polymer processes the quality of the final part stems back in great part to the mixing of the polymer blends and the viscous heating that occurs during the process. To date, these processes have been simulated using the finite difference or finite element methods which rely on cumbersome remeshing techniques, restricting the analysis to simple geometries. However, mathematical manipulation of the governing equations results in boundary integrals, allowing the solution of complicated moving boundary problems without domain meshing. The resulting boundary element model and simulation results of flow with heat transfer and the blending of two or more fluids of different viscosity effects during mixing of polymer blends is presented in this paper. The results give insight to the complex phenomena that take place during mixing processes.
Flow Simulation of a Polymer Melt in a Roller Die
Authors: Kegasawa T. , White J. L. 
Published: December 2013

Abstract
The flow characteristics of Newtonian and non-Newtonian fluids in a roller die are simulated. Both pre-form and Tmanifold entry regions are considered. Calculations are made using a modified Flow Analysis Network procedure. We take into consideration the interaction of roller dies with the screw extruders that feed them. We show operating conditions that can cause starvation to develop in screw extruders feeding roller dies.