bluuebunny/crossref_metadata_2025 huggingface dataset:
The glass transition temperature of filled polymers and its effect on their physical properties
Authors: Droste D. H. , Dibenedetto A. T.
Published: April 2003

The glass transition temperature, dynamic shear moduli, and bulk viscosities of Phenoxy PKHH (a thermoplastic polymer made from bisphenol‐A and epichlorohydrin) filled with glass beads and Attapulgite clay were investigated. The glass temperature of the polymer increased with increasing filler concentration and with increasing specific surface area of the filler. The data were interpreted by assuming that interactions between filler particles and the polymer matrix reduce molecular mobility and flexibility of the polymer chains in the vicinity of the interfaces. From the measured moduli and the viscosities of the filled and unfilled materials, the modulus reinforcement ratio in the glassy state and the relative viscosity in the viscous state were obtained as functions of the filler type and concentration. The relative modulus for the glass bead composite system follows the Kerner equation, while the clay‐filled systems exhibit slightly greater reinforcement. The relative viscosities are strongly temperature dependent and do not follow conventional viscosity predictions for suspensions. It is suggested that the filler has a twofold effect on the viscosity of the composite materials; one is due to its mechanical presence and the other is due to modifications of part of the polymer matrix caused by interaction. Using the WLF equation to express all modifications of the matrix, one can isolate a purely mechanical contribution to the viscosity reinforcement. This mechanical part is approximately bounded by the theoretical predictions of Kerner,32 Mooney, 36 and Brodnyan,41 for suspension viscosities.
Studies on disulfide‐crosslinked nylon. II. Stress relaxation of disulfide‐crosslinked polycaprolactam fibers in water
Authors: Miyauchi Shin'Nosuke , Sakamoto Munenori , Tonami Hiroaki
Published: April 2003

The stress relaxation at 100% elongation in water was investigated for disulfide‐crosslinked polycaprolactam (DSPC) fibers prepared from N‐mercaptomethyl polycaprolactam. The stress decreased faster with increasing temperature and with increasing mercaptan content of the fiber. Little stress decay took place when the fiber was treated with a mercaptan‐blocking reagent. It was concluded that the controlling mechanism of the stress relaxation was the mercaptan/disulfied (SH/SS) interchange reaction. The remanent stress observed for the stress relaxation was fairly high and increased with decreasing mercaptan content of the fiber. The stress decay curve was not Maxwellian. It has been suggested that the concentration of mercaptan that could not participate in the interchange with stressed disulfide bonds increased with increasing cycles of the interchange reaction. A kinetic equation is presented and the activation energy of the SH/SS interchange reaction was evaluated as 22.3–23.9 kcal/mole. The stress relaxation of DSPC fibers in dilute β‐mercaptoethanol was also studied. The stress decreased more rapidly to almost zero and the decay curve was Maxwellian. The activation energy of the reaction was 17.1 kcal/mole. These results were compared with the stress relaxation of wool fibers.
Oxidation of bisphenol a polymers
Authors: Gesner B. D. , Kelleher P. G.
Published: April 2003

Polysulfone, polycarbonate, and phenoxy resins were aged under thermal and ultraviolet light conditions. Thermoxidative processes in polysulfone and polycarbonate are of such minor significance as not to impart noticeable losses in these materials below 125°C. In phenoxy, however, thermal oxidation above 100°C results in rapid deterioration of all physical properties. This probably results from the low glass transition temperature of this polymer. Photo‐oxidation rapidly degrades polysulfone. This appears to be a consequence of scission at the sulfone link. In polycarbonate, however, the only serious result of short‐term irradiation is discoloration. For phenoxy resin, crosslinking through reactions at the hydroxyl group is the principal result of photo‐oxidation. In all processes the bisphenol A portion of the three polymers appears to play only a small role.
Failure mechanisms in peeling of pressure‐sensitive adhesive tape
Authors: Aubrey D. W. , Welding G. N. , Wong T.
Published: April 2003

Studies on the peel behavior of pressure‐sensitive tape comprising a polyester backing and polyacrylate adhesive have shown that, in peeling from a plane glass surface, three fundamentally different modes of peeling may be distinguished, depending upon the rate of pulling. At low rates, deformation by flow of the adhesive appears to determine the peel behavior and the peel force is strongly rate dependent. At high rates, little or no viscous deformation of the adhesive occurs and the peel force is independent of rate. At intermediate pulling rates, cyclical instability of made of failure involving alternate storage and dissipation of elastic energy in the backing, results in the phenomenon of “slip‐stick” peeling, in which failure is jerky and regular. Results have been obtained which show how the pulling rates at which transitions from one mode of peel to another occur, and the peel force values for a given type of failure, depend upon such factors as molecular weight of adhesive, thickness of backing film, and angle of peeling.
Measurement of diffusion coefficient and partition coefficient of sodium in nonionic polymer membranes
Authors: Yasuda H. , Lamaze C. E.
Published: April 2003

The difficulties involved in the measurement of the partition coefficient and diffusion coefficient of NaCl in hydrophilic polymer membranes are examined by the initial rate and late‐time analysis of desorption data for three nonionic polymer systems. The late‐time analysis, based on the plot of the logarithmic relative desorption versus time, was found to be useful when the diffusion is Fickian and the magnitude of D2/l2 is small. Depending on the magnitude of D2/l2, an accurate measurement of k2 and determination of D2 cannot be achieved without correction for the effect of surface salt solution, impossible with late‐time analysis. The initial rate measurement was found more versatile for general non‐Fickian diffusion and it gave a means of correction of the errors involved in estimating the partition coefficient. In general, the diffusion of NaCl in hydrophilic polymers is not ideal Fickian and the discrepancy between the two analyses is appreciable.
Photocrosslinking of stilbene‐modified polymers
Authors: Stuber F. A. , Ulrich Henri , Rao Durvasula V. , Sayigh A. A. R.
Published: April 2003

The reactions of trans‐2,5‐dimethoxy‐4′‐aminostilbene with poly(maleic anhydride‐co‐methylvinyl ether) and trans‐2,5‐dimethoxy‐4′‐isocyanatostilbene with poly(oxy‐1,4‐phenyleneisopropylidene:1,4‐phenyleneoxy‐2‐hydroxytrimethylene) yield polymeric systems which undergo rapid crosslinking upon short exposure to ultraviolet light. The extent of photocrosslinking as a function of exposure time was determined by the decrease of the trans‐stilbene ultraviolet absorption at 350 nm.
Radiation chemical studies of protein reactions: Effect of amino acids on optical rotation
Authors: Nisizawa Mizuho
Published: April 2003

Monosodium 1‐glutamate, disodium inosine‐5′‐monophosphate, disodium guanosine‐5′‐monophosphate, calcium d‐pantothanate, 1‐arginine, and 1‐aspartic acid were found to protect the changes in the internal relationships of the atoms in the protein molecule from radiation damage. The behavior of the optical rotation was determined. The empirical equation for the protective effect is given by [α] f = b − a log X, where [α] f is the final specific rotation of the solution, X is the concentration of the amino acids, and a and b are adjustable constants.
Radiation chemical studies of protein reactions: Effect of protectors on the breaking of secondary bonding in protein
Authors: Nisizawa Mizuho
Published: April 2003

Radiation protective effect of the breaking of secondary bonding in protein was examined with sodium benzoate, monosodium 1‐glutamate, 1‐arginine, and thiourea, and the behavior of viscosity against the protector was obtained. An experimental equation for the viscosity change is given by ηred = b − a log X, where ηred is the reduced viscosity of the solution, X is the protector concentration, and a and b are adjustable constants.
The shear modulus of flowing polyethylene melts
Authors: Cooper Winifred M. , Pollett W. F. O.
Published: April 2003

Tests on three low‐density polyethylene melts over a range of temperatures and shear rates, using a Weissenberg rheogoniometer, have enabled the reduced shear modulus to be obtained as a function of shear rate at the initiation of shearing and at various subsequent stages. For the two polymers which gave plateau values of modulus during the course of shearing these were in good agreement with figures quoted in the literature, but the initial modulus (measured on one polymer) was an order of magnitude higher. This supports the view that a network structure exists in the polymer at rest and is disrupted in the early stages of shearing. It was not possible to obtain unequivocal evidence that the equilibrium modulus decreases with amount of shearing, as required by the hypothesis that rheological breakdown is caused by a reduction in molecular entanglements.
Poly(α,α,α′,α′‐tetrafluoro‐p‐xylylene)
Authors: Chow S. W. , Loeb W. E. , White C. E.
Published: April 2003

Poly(α,α,α′,α′‐tetrafluoro‐p‐xylylene) was prepared by the pyrolysis of cyclo‐di‐(α,α,α′,α′‐tetrafluoro‐p‐xylylene) and by the pyrolysis of α,α′‐bis(alkylsulfonyl)‐α,α,α′,α′‐tetrafluoro‐p‐xylene. The pyrolysis of α,α′‐dibromo‐α,α,α′,α′‐tetrafluoro‐p‐xylylene also gave the polymer, but the method is less satisfactory. Poly(α,α,α′,α′‐tetrafluoro‐p‐xylylene) shows remarkable thermal and oxidative stability at elevated temperatures. Useful mechanical and electrical properties are retained after aging for 3000 hr at 250° in air. After initial change due to crystallization, tensile strength remains near 10,000 psi, elongation above 5%, and dielectric constants and dissipation factors at approximately 2.4 and .001, respectively.
Multiple detectors for molecular weight and composition analysis of copolymers by gel permeation chromatography
Authors: Runyon J. R. , Barnes D. E. , Rudd J. F. , Tung L. H.
Published: April 2003

The use of a single detector in gel permeation chromatography (GPC) for samples of varying composition leads to erroneous conclusions. With certain simplifying assumptions, a gel permeation chromatograph equipped with properly selected dual detectors yields composition and molecular weight distribution information that is meaningful. Examples discussed are a mixture of homopolymers and a sample supposed to have been a styrene–butadiene block copolymer. The ultraviolet absorption is used in conjunction with the refractive index trace to give qualitative information that is much more informative than could be obtained with one detector. Calibration of the relative responses of the detectors to each of the components of the mixture is described, and these calibrations are used to calculate point‐by‐point composition, molecular weights, and molecular weight averages.
Calibration of instrumental spreading for GPC
Authors: Tung L. H. , Runyon J. R.
Published: April 2003

The proper use of the method for correcting instrumental spreading in GPC requires a precise calibration of the spreading characteristics of the instrument. Heretofore, such a calibration could be obtained only through the tedious reverse‐flow experiments. A more rapid method of calibrating instrumental spreading is presented in this work. This method uses the leading halves of the chromatograms of several standard polystyrene samples. These chromatograms are normally used in the calibration of molecular weight; additional experimental steps are therefore not required. The calculation of the instrumental spreading characteristics from these chromatograms is also relatively simple. The instrumental spreading characteristics were found to depend on the elution volume but not on the nature of the polymer. Thus, calibration results from using polystyrene standards can be used to treat chromatograms for other polymers. For the present GPC instrument, the spreading was found to reach a maximum at an elution volume near 400,000 in polystyrene molecular weight. The existence of this maximum is in agreement with observations made by other investigators and is and indication that diffusion in the mobile phase is not an important contribution to instrumental spreading. The problem of skewing or tailing is discussed. Indication of skewing was observed for one of the higher molecular weight polystyrene samples but the extent of skewing was not severe at the present flow rate of 2 ml/min.
Viscosity of polystyrene near the glass transition
Authors: Penwell Richard C. , Porter Roger S.
Published: April 2003

A quantitative explanation is given for the apparent viscosity increase with increasing capillary shear rate for polystyrene at temperatures approaching the glass transition, Tg. Possible shifts in Tg as a function of the parameters shear rate, frequency, and pressure are interrelated to viscosity changes. Experimentally, the Instron capillary rheometer and the Weissenberg rheogoniometer provided a means for uncoupling the variables for individual consideration. Calculated and experimental data for the apparent viscosity as a function of the given parameters are presented and discussed. The explanation of the apparent viscosity increase in capillary flow can be quantitatively explained through the pressure dependence of Tg. Brief mention is made of the pressure effects on the Bagley and Rabinowitsch corrections normally made in capillary measurements.
A comparison of the dielectric method with density, moisture regain, and x‐ray diffraction methods of determining fine structure in cellulosic materials
Authors: Venkateswaran A.
Published: April 2003

A comparison between the dielectric method and density, moisture regain, and x‐ray diffraction methods of estimating crystallinity in cellulosic materials is presented. The merits of the dielectric method compared to the other methods are discussed. Although the permittivities of completely crystalline and completely noncrystalline celluloses are not directly measureable, the use of extrapolated values for completely crystalline and completely noncrystalline celluloses make it possible to assign a percentage crystallinity to a given material from a single permittivity measurement. Capacitance measurements are very sensitive, accurate, and rapid. Therefore, the dielectric method is capable of following small and rapid changes in crystalline content arising from mechanical, chemical, or thermal treatments. In such a study, permittivities of completely crystalline and completely noncrystalline celluloses are not required. Since the relationship between permittivity and crystallinity is linear, it appears reasonable to continue to represent the fine structure of a cellulosic material by a simple model of a mixture or two hyprothetical components: “crystalline” and “noncrystalline” cellulose and to retain the concept of “percentage crystallinity” in its present form.
Stiffness of molecular chain of synthetic rubber
Authors: Furukawa Junji , Yamashita Shinzo , Kotani Teizo , Kawashima Masaaki
Published: April 2003

The principal polarizabilities of rubber molecules including copolymers were evaluated by the arithmetic sum of the polarizabilities of the components. The mean polarizabilities thus calculated are in good accordance with those from the refractive indices. The anisotropic polarizabilities of polymeric units for several kinds of rubbers were calculated and compared with those estimated from stress‐optical coefficients. Length or molecular weight of a statistical link thus estimated is used as a measure of stiffness of rubber molecules. There is a good accordance in statistical links between anisotropic and viscosity measurements in theta solvent. The molecular weight or length of a statistical link thus obtained is found to be compatible with the value calculated from end‐to‐end distance in theta solvent. The ultimate elongation of rubber is correlated with the stiffness and can be estimated from the measure of stiffness of the chain.
Anisotropy of styrene–butadiene rubber
Authors: Furukawa Junji , Kotani Teizo , Yamashita Shinzo
Published: April 2003

Anisotropy of styrene–butadiene rubber (SBR) was investigated. The anisotropy of the copolymer varies linearly with the styrene content and the ultimate value coincides with that of polystyrene at elevated temperature. From these facts, the transverse configuration of the pendant phenyl group is estimated irrespective of the styrene content of SBR.
Rotating spherical interlayer (RSI) measurement of the dynamic mechanical properties of elastomers
Authors: Kaelble D. H.
Published: April 2003

An analysis of simple shear in a rotating spherical interlayer is presented. The theory provides design criteria and operating equations for a new method of measuring the dynamic mechanical properties of soft viscoelastic polymers. The storage component of the dynamic shear modulus G′(ω) = 3F1hm2/2πr4(3 sin ϕ + sin3ϕ) (ΔXt − K1F1) and the loss tangent than δ = [F2(ΔXt − K1F1) − K2F1F2]/[F1(ΔXt − K1F1)− K2(F2)2] are expressed in terms of the inner radius r, thickness, h, and are angle ϕ of sample extending from the rotational equator; the biaxial dynamometer compliances K1, K2; the imposed dynamometer displacement ΔXt; and the spherical interlayer storage and loss forces F1, F2. New instrumentation involving a rotating spherical interlayer (RSI) transducer and a rotational accessory to the Instron provides measurements from 0.001 to 45 cycle/sec at temperatures from −50° to 200°C. A comparison of RSI data, treated by time–temperature superposition, and literature values of dynamic response in polyisobutylene confirms both theory and method.
Transparent barrier resins with high nitrile content
Authors: Hughes E. C. , Idol J. D. , Duke J. T. , Wick L. M.
Published: April 2003

The effect of 30–49 wt‐% nitrile group content on the properties of copolymers is demonstrated. The nitrile is furnished by either acrylonitrile or methacrylonitrile. The exceptional resistance of such high nitrile content resins to the passage of gases and of solvents is shown and variations therein demonstrated for different comonomers. Transparent, tough, grafted polymers of good color are described which retain these properties. These qualities, combined with low second‐order transition temperatures and adequate heat deflection temperatures, provide polymers of interest wherever containment and barrier are desired. Bottles, thermoformed containers, etc., could benefit from the use of some of the polymers described.
Thermal analysis of nitro‐substituted epoxide polymers
Authors: Fleming Gerald J.
Published: April 2003

The thermal properties of a number of nitro‐substituted and analogous nonnitro‐substituted expoxide polymers were investigated. Dramatic increases in char yield and decreases in maximum rate of weight loss were observed for the nitro‐substituted systems compared to their nonnitrated analogs. These effects were enhanced when highly functional and highly aromatic epoxide resins were used. The sample size and heating rate employed had pronounced effects upon the amount of char formed during thermal degradation. Analysis of char residues indicates heteroring formation for the nitro‐substituted systems during pyrolysis.
Cellulose graft copolymers. I. Graft copolymerization of ethyl acrylate with γ‐irradiated cellulose from methanol–water systems
Authors: Nakamura Yoshio , Hinojosa Oscar , Arthur Jett C.
Published: April 2003

Ethyl acrylate was graft‐copolymerized with γ‐irradiated, purified cotton cellulose from methanol–water systems. The accessibility of the free radicals in the irradiated cellulose to water, methanol, ethyl acrylate, and methanol–water solutions was determined by electron spin resonance spectroscopy. The maximum scavenging of the radicals was recorded with the irradiated cellulose was immersed in methanol–water solution which had a composition of 50/50 vol‐%. When ethyl acrylate was added to methanol–water solution (50/50 vol‐%), maximum grafting on the irradiated cellulose occurred at a concentration of ethyl acrylate of about 20 vol‐%. As the concentration of ethyl acrylate was decreased, maximum grafting occurred in solutions containing less than 50 vol‐% methanol. It was also noted that maximum grafting of ethyl acrylate in methanol–water solutions to irradiated cellulose occurred at boundry conditions, that is, conditions where the ternary mixture was still one phase, slightly different from compositions which caused the mixture to separate into two phases. From methanol solution, maximum grafting occurred at a concentration of ethyl acrylate of 80 vol‐%. The extent of grafting from methanol was less that obtained from methanol–water solutions at lower concentrations of ethyl acrylate. The accelerative effects of water was considered to be due to the Trommsdorff effect.
Study of polyethylene blends by differential scanning calorimetry
Authors: Sato Tetsuo , Takahashi Mikio
Published: April 2003

The melting behaviors of linear and branched polyethylene blends were studied using a Perkin‐Elmer DSC‐1B differential scanning calorimeter. Three endothermic peaks were occasionally observed in the DSC thermogram on polyethylene blends which had not been subjected to any isothermal annealing. The nature of the third intermediate temperature peak is discussed in relation to the prior cooling rate, the blend composition and the molecular structures of both components. The results appear to indicate that the intermediate peak is associated with the fusion of the hybrid crystallites of linear and branched polyethylenes. These hybrid crystallites seem to be formed on the rapid cooling of lean linear polyethylene blends. Blends containing low molecular weight branched polyethylene seem inclined to form the hybrid crystallites.
Electron beam irradiation of an ultrahigh molecular weight polyethylene resin in air
Authors: Brenner W. , Adler A. , Oswald H. J. , Turi E. A.
Published: April 2003

High molecular weight linear polyethylene has been irradiated in the solid state by high energy electrons. The irradiated samples were characterized by differential scanning calorimetry, solubility properties, and stress‐strain measurements. A failure mechanism is proposed for the observed embrittlement of the polymer.
Poly‐2‐oxazolidones as cryogenic adhesives
Authors: Sandler Stanley R.
Published: April 2003

Adhesives data are presented at −320° to +400°F for adhesion to aluminum or stainles steel to indicate that poly‐2‐oxazolidone‐type adhesives give poor results when conpared to epoxy amine, polyurethane prepolymer amine, or a mixture of the latter two resins.
Characterization of sulfur‐cured styrene–butadiene copolymer rubbers and their polybutadiene blends
Authors: Clark J. K. , Scott R. A.
Published: April 2003

Dissolution of sulfur‐cured, carbon black‐loaded copolymers and their blends with cis‐1,4‐polybutadiene (PBD) are brought about by boiling with o‐dichlorobenzene which contains a small amount of 2,2′‐dibenzamidodiphenyl disulfide. The resulting slurries are subjected to a sequence of separations which include high‐speed centrifugation to remove solids, and solvent precipitation followed by filtration to isolate the precipitates. The precipitates are washed with solvent to remove soluble organic materials followed by carbon disulfide washing to dissolve the polymers. Cast films of the polymers are obtained by evaporating the carbon disulfide washings onto sodium chloride discs. The infrared spectra of the cast films of these preparations are very similar to those of their respective polymers prior to loading and curing. Calculations for relative concentrations of bound styrene and PBD microstructures permit nominal identification of the kinds of styrene–butadiene rubber and the amounts of cis‐1,4‐PBD used in a cured rubber formulation. Absorption bands used are near 3.35 μ for cis‐1,4‐PBD, 6.65μ for bound styrene, 10.35 μ for trans‐1,4‐PBD; and 11.0 μ for vinyl‐1,2‐PBD. Efforts are being made to improve the data by using a grafting infrared instrument and also to extend the calibrations to include other rubber blends.
Unsteady flow of viscoelastic fluids
Authors: Chong J. S. , Vezzi D. M.
Published: April 2003

Theoretical solutions for unsteady flow of a three constant Oldroyd fluid and a second order fluid under several different flow conditions of practical interest are obtained. The response of these fluids to suddenly applied external force is investigated in each case. Without using the stick‐slip boundary condition at the wall, it is possible to show that pressure oscillation occurs with both fluids under a certain case.
The analysis of polyurethane foams. I. Identification of components
Authors: Dawson B. , Hopkins S. , Sewell P. R.
Published: April 2003

A scheme of qualitative analysis is presented for the identification of the constituents of polyurethane foam products, or indeed polyurethane‐type materials in general. Elastomeric and cellular polyurethanes are analyzed by hydrolysis to simpler compounds which are then separated and identified. The methods of identification employed include infrared and nuclear magnetic resonance spectroscopy, gas chromatography, and thin‐layer chromatography.
Antioxidant effects in PVC plasticized with DIDA
Authors: Darby J. R. , Touchette N. W. , Sears J. K.
Published: April 2003

Antioxidants such as bisphenol A (BPA) have long been recommended for retention of physical properties on oven‐aging of PVC plasticized with certain plasticizers. We have shown how BPA inhibits oxidative fragmentation of plasticizers such as diisodecyl adipate (DIDA) and thus decreases apparent volatility, and how it improves retention of modulus, elongation, and low temperature flexibility. Low concentrations are more beneficial than either zero or high concentrations, especially on longer aging. At higher concentrations, although the plasticizer is retained in the PVC, it becomes less efficient at low temperature, and low‐temperature flex is impaired while elongation is preserved. DIDA exudes during oven‐aging unless oxidation occurs to prevent it. When BPA is present, exudation is worst at the most efficient concentrations of antioxidant. This appears to be the normal incompatibility of DIDA at 105°C which is permitted by the antioxidant. On oxidation, the dielectric constant of DIDA rises into the 4–8 range, signifying compatibility with PVC, and the DIDA does not exude.
Heat stability of chemically crosslinked polyethylene
Authors: Narkis M. , Tobolsky A. V.
Published: April 2003

Heat stability in air of chemically crosslinked polyethylene loaded with medium thermal (MT) carbon black was studied as a function of temperature and carbon black content. Weight loss at 200° to 250°C is practically independent of the carbon black concentration. Modulus–temperature curves are changed with various heat treatment periods at 225°C. These curves show that the rubbery modulus (amorphous state) increases with increasing the heating period, while the modulus of the partially crystalline polymer goes through a minimum and then increases. Continuous stress‐relaxation and intermittent stress curves show the existence of degradation and crosslinking reactions, the latter becoming more important at higher temperatures or longer times. The degradation reaction is practically independent of the carbon black content while the crosslinking reaction at 225°C is faster with increasing MT black concentrations. It is concluded that reasonable heat stability, in the crosslinked polyethylene compounds studied, can be obtained at temperatures lower than 150°C.
Effect of multiple feeds on a termination‐free polymerization in continuous stirred tank reactors
Authors: Teaney F. G. , Anthony R. G.
Published: April 2003

The effect of monomer and initiator feeds to each of a series of continuous stirred tank reactors (CSTR) on the molecular weight distributions, average molecular weight, polymer production rate, and initiator and monomer conversions is studied for the termination‐free polymerization system. For initiator feed concentrations less than 0.001 mole/liter, the distribution becomes narrower as the polymer progresses from reactor 1 to reactor 3. But for concentrations of initiator of 0.01 mole/liter, the distribution may be broadened from reactor 1 to reactor 3. The broadening of the distribution results in the production of a lower molecular weight polymer.
Friction of polymer films. III. Migration of lubricants
Authors: Owens D. K.
Published: April 2003

The migration of the lubricant stearamide to the surface of vinylidene chloride–acrylonitrile copolymer coatings on regenerated cellulose film was studied by measuring the effect of heating the coatings on friction and critical surface tension. The surface quantity of stearamide was maximum at a heating temperature of 65°C. Above this temperature stearamide was lost from the surface. Up to 65°C the migration of lubricant obeyed first‐order kinetics and the activation energy was calculated. Below 65°C diffusion to the surface appears to be the controlling process, while above 65°C evaporation from the surface is probably the controlling process.
Conditioning polytetrafluoroethylene surfaces for use in vascular prostheses
Authors: Miller M. L. , Postal R. H. , Sawyer P. N. , Martin J. G. , Kaplit M. J.
Published: April 2003

Polytetrafluoroethylene surfaces have been treated to reduce thrombogenicity in order to make them suitable for use in prosthetic devices that come in contact with blood. This was done by first etching the surface with potassium in liquid ammonia to produce double bonds and then using these double bonds as sites for grafting on polyacids or as sites for chemical reactions. Tubes so treated were tested for thrombo‐genetic activity by implantation in the thoracic aorta or inferior vena cava of dogs. These tests showed that the thrombogenicity of a polytetrafluoroethylene surface can be reduced by attaching negatively charged groups provided the surface concentration of these groups is not too high (order of 1–2 × 10−6 equivalent per cm2 geometric area) and provided the distribution of these groups is uniform. Sulfonic acid groups obtained by chlorosulfonation and carboxyl groups attached by grafting tert‐butyl crotonate and hydrolyzing to crotonic acid were effective. Long chains of poly(acrylic acid), poly‐(ethylenesulfonic acid), and poly(vinyl alcohol) sulfate were less effective.
Molecular weight distribution of polystyrene and of butadiene–styrene copolymers prepared in emulsion systems
Authors: Uraneck C. A. , Burleigh J. E.
Published: April 2003

Polystyrene and butadiene–styrene copolymers (SBR) were prepared in emulsion systems with a homologous series of commercial mercaptan modifiers. The molecular weight distribution (MWD) of the sets of polymers changed in a consistant manner when the regulating index of the mercaptan was relatively low. However the shape of the MWD curves appeared distorted in comparsion to theoretical curves when the modifier depleted rapidly and when divinylbenzene was present in the system. The divergence from the theoretical curve is attributed to a higher degree of branching in the high molecular weight fractions. Differences in MWD of SBR made with n‐ and tert‐ dodecyl mercaptans was marked. Notable differences were also found for SBR 1500 samples from the industry at random, but only slight differences were seen in a set of SBR 1503 samples. This study shows how the MWD of polymers prepared in emulsions can be varied simply by use of modifiers with different regulating indexes.
Temperature dependency of bound water of cellulose studied by a high‐resolution NMR spectrometer
Authors: Ogiwara Yoshitaka , Kubota Hitoshi , Hayashi Shoichi , Mitomo Noriko
Published: April 2003

The widths at half‐value of high‐resolution NMR spectra of bound water of cellulose were studied in relation to the temperature change. Two points were made clear: First, the amount of bound water of the cellulose sample can be pointed out with higher accuracy the lower the temperature of the measurement. Second, it is possible to determine in a simple manner the boundary temperature Tc at which water molecules become bound by the cellulose. Tc is characteristic of the cellulose sample of a given water content and corresponds to the glass transition temperature of the water‐containing sample. The measurements appear to be readily applicable to other hydrophilic polymers.
Concentration dependence of the diffusion coefficient in polymer solution and molecular weight distribution determined by the diffusion method
Authors: Matsuda Hideomi , Aonuma Hidehiko , Kuroiwa Shigetaka
Published: April 2003

The effects of the concentration dependence of the diffusion coefficient of a polymer solution (polystyrene in benzene and cyclohexane) in determining molecular weight distribution by the diffusion method are briefly discussed. The value of the ratio Dm0/DA0 in a good solvent was found to be close to 1.0 for a polydisperse polymer and less than 1.0 for monodisperse polymers. Molecular weight distribution curves of the polydisperse sample were obtained by the diffusion method in cyclohexane and benzene, respectively. The molecular weight distribution curve obtained for the polymer used in benzene solution looked as if the polymer had a narrow molecular weight distribution. The phenomena cited above were interpreted in the light of the concentration dependence of the diffusion coefficient of polymer solutions.
Thermal analysis of compounded poly(vinyl chloride)
Authors: Dunn P. , Ennis B. C.
Published: April 2003

Differential thermal analysis of mixtures of poly(vinyl chloride) and dioctyl phthalate shows a compound endothermic peak due to decomposition of both polymer and plasticizer. The thermal behavior of other plasticizers is similarly affected in the presence of poly(vinyl chloride). The addition of zinc oxide or ferric oxide decreases the thermal stability of the mixture and, under isothermal conditions, a resultant induction period allows the estimation of an activation energy for the dehydrochlorination of poly‐(vinyl chloride) and of the relative effectiveness of thermal stabilizer systems.
Comparative gel permeation chromatography calibration techniques in oxidative coupling polymerization
Authors: Revillon A. , St. Pierre L. E.
Published: April 2003

Gel permeation chromatography was utilized in measuring the kinetics of the oxidative coupling polymerization of 2,6‐dimethylphenol. The elution curves at the early stages of reaction were analyzed by two methods of calibration, specifically by comparison to the elution times of oligomers up to the 6‐mer level, and by the classical counts method. The two methods give similar results, both indicating a polymerization pattern of the general condensation type and increasing dispersity of molecular weight with degree of polymerization.
Automatic recording capillary viscosimeter with dilution
Authors: Gramain Ph. , Libeyre R.
Published: April 2003

A capillary viscosimeter with automatic determination and recording of flow times of liquids up to 200°C is described. This viscosimeter, which is specially suited for studies of polymeric solutions, includes an automatic dilution system and determines intrinsic viscosity with a precision better than 0.01%.
Thermodynamic description of relaxation phenomena in polymers
Authors: Bartenev G. M. , Zelenev Y. V. , Borodin I. P.
Published: April 2003

The analysis of various deformations of an ordinary elastic body and a highly elastic body accompanied by temperature changes shows that, in distinction to isothermic conditions, under adiabatic conditions the dynamic characteristics of a polymer in a highly elastic state depend on the amplitude of the applied stress (in particular, their position on a frequency or temperature scale), which is associated with the entropic nature of the highly elastic deformation.

When describing the relaxation phenomena caused by the response of the system of interacting kinetic units to the external perturbation, the nonequilibrium thermodynamics relationship between the “flow” and the “generalized force” is nonlinear even at small deviations from the equilibrium state. In this case the dependency of the kinetic factor on the response can be presented by eq. (40).

Considered herein were such particular relaxation phenomena as creep and stress relaxation. The calculated dependencies agree well with the experimental data.
Molecular structure of chain‐extended polymeric diols
Authors: Randall J. C. , Hamner W. F. , Taylor H. A.
Published: April 2003

The molecular structures of a series of chain‐extended polycaprolactone diols were studied by nuclear magnetic resonance (NMR) and conventional wet chemical techniques. Hydroxyl end group and per cent nitrogen values were obtained by phthalation and automated micro‐Dumas techniques, respectively. The value of the NMR technique is demonstrated is demonstrated in providing information regarding the total structure of the polymer. Molecular weight and per cent nitrogen values obtained by this procedure for most samples agree better than 10% with results obtained by the chemical methods.
A rheological characterization of SBS block copolymers
Authors: Arnold K. R. , Meier D. J.
Published: April 2003

The dynamic viscosities of styrene–butadiene–styrene (SBS) block copolymer melts with different end‐ and midblock sizes are given as a function of frequency at several different temperatures. The data exhibit two distinct regions, a high frequency region where the response is typical of thermoplastics and a low frequency region where the viscosity continually increases with decreasing deformation rates. These results are successfully explained in terms of the formation of polystyrene domains in the low frequency region. The correlations given for the rheological properties should provide additional insight to the processing of these materials.
The reaction of activated vinyl compounds with cotton cellulose via internal catalysis
Authors: Rowland Stanley P. , Brannan Mary Ann F.
Published: April 2003

The reactions of a variety of activated vinyl compounds with cotton cellulose fabric containing quaternary ammonium hydroxide substituents were explored. Each reaction, catalyzed by the basic groups in the cellulose, was followed to or near the point of leveling off. The results are analyzed and discussed in terms of accessibility of the cellulosic compositions and in terms of the efficiency of the quaternary ammonium substituents as catalysts for the addition reactions. Estimates of relative forward rate constants (kf) and equilibrium constants (K) for the reactions were made. The values of kf for reactions of the vinyl compounds with the quaternary ammonium celluloses show a relative order which is similar to that for the reactions of the vinyl compounds with simple alcohols. Evidence is presented to indicate that, in some cases, the addition of vinyl compounds is accompanied by anionic‐catalyzed graft polymerization.
A two‐capillary viscosity method monitored by an analytical balance
Authors: Almin Karl E. , Swenson Harold A.
Published: April 2003

By the simultaneous use of two capillaries, one for solution and one for solvent, and determination of the weight difference of the effluxing liquids with an analytical balance, it is possible, without time measurement, to determine the relative viscosity of a solution with high accuracy. Nylon capillaries were used in the experiments. The equation necessary for calculation of the relative viscosity is derived. The method is particularly useful for very dilute polymer solutions and for the study of low molecular weight substances and lends itself to study of the corrections common in capillary viscometry. Literature values for glucose were confirmed with the method, but low values were found for sodium chloride. The use of bundles of capillaries makes it possible to study the boundary between solvent and solution and to study the possible migration of polymer molecules, in terms of size, toward or away from the walls under conditions of capillary flow. The method can also be used for studying viscous properties of liquids that vary with time.
Solventless processing of modified poly(vinyl fluoride) and its properties
Authors: Stallings John P. , Paradis Robert A.
Published: April 2003

The properties of fluorocarbon plastics have made them very desirable for numerous new applications. The DALVOR X‐6500 series of fluoropolymers can be easily fabricated without the use of solvents. General compound information, including pigmentation, lubrication, and rheology data, is presented as well as chemical resistance, weathering, and electrical data. Processing parameters for producing both flat and blown films are given, along with recommended types of equipment. Data are presented on fluid bed coating and various other applications are discussed.
Extraparticle diffusional effects in gel permeation chromatography. I. Theory
Authors: Biesenberger J. A. , Ouano A.
Published: April 2003

A systems approach is applied to the analysis of chromatogram resolution dispersion, or zone broadening, in gel permeation chromatography (GPC). Three possible sources of dispersion are considered; these are: the packed columns; the empty tubing between pump and columns, columns and detector, etc.; and the detection system, viz., the differential refractometer cell. It is shown that empty tubing can contribute significantly to the degree of dispersion and to skewness of elution curves and that this dispersion should depend on molecular weight of solute (polymer) and diameter and length of the tubing. The importance of dispersion in the empty tubing is compared with that in the packed columns and refractometer cell.
Diffusion coefficients of liquids in polymer membranes by a desorption method
Authors: Fels Morton , Huang Robert Y. M.
Published: April 2003

A method to obtain the diffusion coefficients and free volume parameters from desorption data for organic liquids in polymer films is presented. The method consists of fitting a numerical solution of the diffusion equation to experimental desorption data. Some problems that arise in the solution of the diffusion equation are discussed and results for a benzene–polyethylene system are presented.
Infrared determination of the composition of copolymers and terpolymers of propene and butene‐1 with and without octene‐1
Authors: Wegemer N. J.
Published: April 2003

An infrared spectrophotometer was calibrated for the quantitative determination of butene‐1 in copolymers with propene, and of butene‐1 and limited concentrations of octene‐1 in terpolymers with propene. 14C‐tagged standards were used for the butene‐1 calibration while standards for the octene‐1 calibration were prepared from a homopolymer by blending. Films were pressed from the standards, and the absorbance per mil thickness was correlated with composition. For our instrument, wt‐% C4 = 510 (A/mil) at 766 cm−1, and wt‐% C8 = 539 (A/mil) at 725 cm−1. No special steps were required to eliminate the effects of crystallinity.
The maximum extent of reaction in gelled systems
Authors: French David M. , Strecker Ruediger A. H. , Tompa Albert S.
Published: April 2003

Just how far reactions can go after gelation during the cure of telechelic prepolymers has been a debatable point for some time. Utilizing a recently devised method,7 the curing reactions of some telechelic prepolymers were followed after the gel point. Extents of reaction above 90% occurred only in systems of average functionality close to two, functionality being the average number of reactive groups per molecule. Among systems of higher functionality, maximum extents of reaction of about 70% were most common. The final extent of reaction was only a few per cent above the extent of reaction at the gel point. The maximum extent of reaction varied with the concentration of reactive species and the relationship was a linear one at each functionality of the system. The data were consistent with PA2/r = {0.88/[(h − 1)(j − 1)]} + 0.10 where PA is the fraction of prepolymer reactive groups initially present which have reacted, r is the ratio of the initial number of crosslinking groups to prepolymer reactive groups, and h and j are weighted average functionalities of the two reactants. It is suggested that the limiting factor in defining the final extent of reaction in these systems is the accessibility of reactive groups as determined by solid geometry rather than thermodynamics or reaction kinetics. The final extent of cure is regularly dependent on functionality and one cannot regard functionality and maximum extent of reaction as independent variables.
The effect of crosslinking on the swelling of cotton in solutions of sodium hydroxide and cadoxen
Authors: Evans G. M. , Jeffries R.
Published: April 2003

This paper describes the effects of prior crosslinking in dimethylol ethyleneurea (DMEU) on the swelling of cotton fiber in aqueous solutions of sodium hydroxide and in cadoxen solutions (solutions of cadmium oxide in mixtures of ethylenediamine and water). The degree of swelling in the weaker swelling solutions is markedly reduced by the crosslinking, but in the stronger solutions (particularly in concentrated sodium hydroxide) the effect of prior crosslinking is only small; this is accounted for in terms of a fibril‐tearing mechanism in these stronger solutions. Crosslinking cotton reduces the mercerizing effect of strong alkali solutions (i.e., the disordering and the cellulose I → II lattice change), and also reduces the solubility of the fiber in solutions of cadoxen and cuprammonium hydroxide.
Dilatometric study of the melting point of three high‐pressure crystallized samples of marlex polyethylene
Authors: Waldman N. , Beyer G. H. , Griskey R. G.
Published: April 2003

The melting points of three polyethylenes differing in molecular weight distribution from 47,000 to 147,000 were determined as 141°C ± 0.5°C by dilatometric techniques. Sample preparation procedures were developed to ensure uniform thermal history prior to measuring length as a function of temperature in a precision dilatometer. The specific volume data were reproducible within 0.02%, reflecting the careful annealing procedure used and the extended time allowed for equilibrium to be attained.
Effect of casting conditions on the performance of porous cellulose acetate membranes in reverse osmosis
Authors: Kunst B. , Sourirajan S.
Published: April 2003

Several sets of porous cellulose acetate membranes were made using the same casting solution composition and gelation conditions but varying the casting solution temperature and solvent evaporation conditions. The films were tested in reverse osmosis experiments at 250 psig using aqueous feed solutions containing 3500 ppm NaCl. The results show that the product rate obtained at a given level of solute separation is independent of evaporation time in the range tested and, for a given casting solution composition, the temperature of the casting solution and conditions of solvent evaporation during film formation together constitute an important interconnected variable governing the porous structure of the resulting membranes. These results offer a new approach to the problem of developing more productive reverse osmosis membranes and have led to a new class of porous cellulose acetate membranes capable of giving product rates 100% to 150% higher than those of the best membranes reported, at any given level of solute separation under the experimental conditions used. These results are of practical importance in low‐pressure reverse osmosis applications.
The time dependence of surface energy in cohesive fracture
Authors: Bennett S. J. , Anderson G. P. , Williams M. L.
Published: April 2003

The time‐temperature dependence of the cohesive fracture energy is deduced from experiments on a centrally cracked sheet of butadiene‐acrylonitrile‐acrylic acid viscoelastic terpolymer crosslinked with an epoxy curing agent. Analytic results based upon a cylindrical flaw model of the crack permit the segregation of the fracture energy time dependence from that of the relaxation modulus.