bluuebunny/crossref_metadata_2025 huggingface dataset:
Permeation of ethane–butane mixtures through polyethylene
Authors: Robeson Lloyd M. , Smith Theodore G.
Published: April 2003

Permeation of ethane–butane mixtures a t atmospheric pressure through polyethylene was investigated in the temperature interval of 30–60°C. The integral permeation constant P̄ and the integral diffusion coefficient D̄ of both ethane and butane were satisfactorily correlated by using an exponential and also a linear function of butane concentration. This was attributed to the plasticizing of the film by butane, whose solubility constant is approximately ten times that of ethane in the temperature interval investigated. The separation factor Gi, j defined as the ratio of the permeation constant of butane to the permeation constant of ethane over the range of mixture compositions and temperatures investigated, remained nearly constant at values in the range of 2.8–3.2. The insignificant change in Gi, j is due to the proximity of the activation energies of permeation of ethane and butane (10.95 and 10.75 kcal/mol, respectively) and the similar magnitude of change in the permeation constants with increasing butane concentration. Experiments were run in which the film was initially in equilibrium with the same partial pressure of butane as in the mixture to be studied. It can be shown that the diffusion coefficient of ethane in this case is related to the following function of film position: D = D(o)(β0 + β1x)δ. The time lag of diffusion of ethane in these experiments decreased with inrreasing butane concentration.
GPC data interpretation
Authors: Yau W. W. , Fleming S. W.
Published: April 2003

A rigorous procedure for reducing gel permeation chromatography elution data to differential molecular weight distribution curves is discussed and demonstrated by two sample calculations. The errors introduced by failure to correct the ordinates of the elution curve by means of a differential calibration curve are identified, and a simple graphical conversion procedure is illustrated.
Detection of polymer transition temperatures by infrared absorption spectrometry
Authors: Anton Anthony
Published: April 2003

Infrared bands in the 900–1100 cm−1 region are sensitive to thermal energy. These bands can result from intermolecular coupling, producing the crystal lattice, or from intramolecular coupling of the various atomic groups in a regular helix or coiled chain. In either case an increase in temperature will disrupt the coupling mode, resulting in a form of structural relaxation and a reduction in the integrated absorbance. It is proposed that the temperature at which the peak areas begin to decrease be assigned as the Tg. This is measured by continuously scanning a selected peak in the infrared spectrum of a polymer film while it is heated at a rate of about 1°C/min. Using this technique polyamides (nos. 6,66, and 610) exhibited transitions in the 30–50°C range, and by studying the increase in the free NH region (3440 cm−1) of nylon 66 two other transitions were detected at 80 and 137°C; the latter represents a change in the nylon 66 crystal state. An amorphous film of poly(ethylene terephthalate) displayed a transition at 58–68°C (Tg) and at 85°C, which is the crystallization temperature. Films of poly(vinyl acetate) and polystyrene exhibited transitions at 25–37°C and at 70°C, respectively.
Effects of monomer impurities on the emulsion polymerization of chloroprene and properties of polychloroprene. I. Effect of methyl vinyl ketone
Authors: Sufčák Miloslav
Published: April 2003

The influences of small amounts (up to 2%) of methyl vinyl ketone in chloroprene on properties of polychloroprene and kinetics of the emulsion polymerization of chloroprene with mercaptans as regulators has been studied. Methyl vinyl ketone causes a substantial increase in molecular weight of polymer, which results in increased viscosity, gel formation, lowered plasticity of polymer, deterioration of processability, decreased tensile strength, and high modulus of vulcanizates. Methyl vinyl ketone interferes with the regulation of molecular weight by both primary and tertiary dodecylmercaptan; some differences are due to lower reactivity of tertiary dodecylmercaptan. In the presence of diisopropyl xanthogene disulfide as a molecular weight regulator the polychloroprene properties are not affected by methyl vinyl ketone. All changes in polymer properties have been proved to be caused by the addition reaction of dodecylmercaptan on methyl vinyl ketone, yielding 1‐dodecylthiobutan‐3‐one. This compound itself has no influence on the polymerization of chloroprene. Methyl vinyl ketone has a marked promoting effect on polymerization rates, which accounts for its high reactivity and solubility in the water phase. A fast polymerization of methyl vinyl ketone takes place in the water phase of emulsion polymerization system simultaneously with the reaction of methyl vinyl ketone with dodecylmercaptan.
Radiation chemical studies of protein reactions: Effect of irradiation atmosphere on viscosity
Authors: Nisizawa Mizuho
Published: April 2003

When protein is irradiated by γ‐rays from a 60Co source in various atmospheres such as N2, CO2, H2, O2, and NH3, the effect of the radiation varies with the gases composing the irradiation atmosphere. An empirical equation for the viscosity change was obtained.
Infrared and nuclear magnetic resonance of maleic anhydride copolymers and their half esters
Authors: Saier Eleanor L. , Petrakis L. , Cousins L. R. , Heilman W. J. , Itzel J. F.
Published: April 2003

Infrared and NMR group‐type methods for the analysis of the anhydride content of maleic anhydride copolymers such as poly(maleic anhydride‐co‐α‐olefin) and the half ester content of their reaction products with alcohols are described. The infrared analyses are based on the integrated absorptivities of the anhydride carbonyl and the combination of the acid and ester carbonyl. The NMR method is based on the intensities of the various chemically shifted groups in the copolymer. The use of dimethyl sulfoxide as an auxiliary solvent has made the infrared analysis possible.
Effects of molding conditions on properties of injection‐molded polycarbonates
Authors: Koda Hiroyuki
Published: April 2003

Statistically designed experiments were carried out to study the effects of molding conditions on the properties of two types of polycarbonate, which were synthesized by the solvent process and the melt process, respectively. The properties tested in this study were classified into two groups with respect to the effect of molding conditions. One, which included birefringence, heat shrinkage at 180°C, and surface resistance to Taber abrasion, was mainly affected by stock temperature and was slightly affected by holding pressure. The other, which included resistance to solvent crack, Rockwell hardness, density, and heat shrinkage at 120°C, was affected by mold temperature and holding pressure. Mechanically isotropic moldings with a low degree of frozen orientation could be molded at a high stock temperature and at a low holding pressure, where stock temperature was more effective than holding pressure. Moldings with low residual stresses could be molded at a high mold temperature and at a low holding pressure. Essentially there was no difference in the molding conditions and properties by the method of synthesis. However, under the same molding conditions polycarbonate synthesized by the melt process gave a higher degree of frozen orientation and somewhat more rigid moldings.
Time‐dependent capillary flow of polystyrene
Authors: Rudin A. , Leeder D. R.
Published: April 2003

The nonsteady flow behavior of a characterized commercial polystyrene has been examined in a compressed‐nitrogen‐gas piston viscometer. Nonsteady flow data were erratic with virgin polymer at 173.9°C. Pretreatment of the polystyrene by subjecting the melt to a higher temperature, with or without shear, changed the nature of the time‐dependent flow to that which is generally characteristic of polymers in experiments of this type. The pretreatment had no significant effect on the equilibrium flow curve at the same temperature nor on the molecular weight of the polystyrene. The results are interpreted in terms of changes in the size or nature of supermolecular flow units.
Effect of long‐term oxidation at 200–300°C on six types of aromatic amide and imide resins
Authors: Scala L. C. , Hickam W. M. , Marschik I.
Published: April 2003

Six types of aromatic amide and imide resins in the form of wire enamels, paper, and film were subjected to thermal and oxidative deterioration at temperatures ranging from 200 to 300°C and for aging periods of 3 and 6 months. No HCN was evolved at any temperature and aging time. The main degradation product was, in all cases, carbon dioxide, in quantities increasing as functions of time and temperature. Other materials evolved were, in approximate order of magnitude, carbon monoxide, water, and nitrogen. Traces of acetonitrile were recovered from a film and a paper sample, while benzene, also in trace quantities, was evolved from the wire enamel samples at temperatures ranging from 250 to 300°C.
Ionic binding in pressure‐sensitive adhesive polymers
Authors: Satas D. , Mihalik R.
Published: April 2003

Ionic binding is affected in pressure‐sensitive acrylate‐based copolymers containing carboxylic groups by introduction of Na ions. The tack and peel force of pressuresensitive polymers decreased and the resistance to creep increased with increasing degree of ionic binding. An infrared spectroscopic method for the assay of sodium content has been developed based on the ratio of absorbances at 5.75 and 6.28 μ due to ester carboxyl and ionized carboxyl, respectively.
Effect of the structure of cationic polysulfone on the flocculation of kaolinite
Authors: Ueda Toshio , Harada Susumu
Published: April 2003

The behavior of polycations as flocculants for kaolinite was examined by means of turbidity measurement, with the use of the following four kinds of cationic polysulfones, with molecular weights ranging from 14,000 to 330,000; diallyldimethylammonium chloride SO2 copolymer [P(DADMAmClSO2)], diallyldiethylammonium chloride–SO2 copolymer [P(DADEAmClSO2)], diallylmethylamine hydrochloride–SO2 copolymer [P(DAMAHClSO2)], diallylamine hydrochloride–SO2 copolymer [P(DAAHClSO2)]. The effect of the degree of polymerization on the flocculation was remarkable at low molecular weight range. The flocculation value, which is defined as the quantity of the polycation required to obtain 50% transparency at 660 mμ of the supernatant fluid of 2% kaolinite suspension, was inversely proportional to the degree of polymerization to the 0.734 power in the case of P(DADMAmClSO2). This can be understood as the extension of Schulze‐Hardy's law. The four different kinds of polysulfones having a similar molecular weight show almost the same capacity for flocculation in acidic or neutral solution. In alkaline solution, however, P(DAMAHClSO2) and P(DAAHClSO2) are less effective and have higher flocculation values than P(DADMAmClSO2) and P(DADEAmClSO2), which are classified as polyquaternary ammonium chlorides. Moreover the difference increases with increasing pH. This may be attributable to the difference of the dissociability of the polycation. The degree of dissociation of P(DAMAHClSO2) or P(DAAHClSO2) decreases with increasing pH and more additive is required to neutralize negative charges on kaolinite. On the other hand, P(DADMAmClSO2) and P(DADEAmClSO2) are almost completely dissociated and are good flocculants over a wide range of pH.
Adsorption of cationic polysulfone on bentonite
Authors: Ueda Toshio , Harada Susumu
Published: April 2003

The adsorption of a polycation (diallyldimethylammonium chloride–SO2 copolymer) on bentonite, a hydrophilic and negatively charged clay, was investigated. The cation exchange capacity of bentonite decreased with the adsorption of polycation. From this fact it may be concluded that the adsorption of the polycation on bentonite proceeds in a cation‐exchange manner. Bentonite came to have some anion‐exchange capacity as a result of adsorption of the polycation. This may be attributed to the existence of the parts in the polymer chain which do not take part in the combination with bentonite. The anion‐exchange capacity increased and the complex became somewhat hydrophilic if a simple salt such as sodium chloride was added to bentonite with the polycation. The polymer was not desorbed from the complex by treatment with NaCl or CaCl2. The adsorption reaction of the polymer on bentonite may be considered to be irreversible.
Preparation and properties of copolyesters polymerized in a vented extruder
Authors: Gouinlock E. V. , Marciniak H. W. , Shatz M. H. , Quinn E. J. , Hindersinn R. R.
Published: April 2003

High molecular weight thermoplastic copolyesters from bisphenol A, neopentyl glycol, and terephthaloyl chloride have been prepared by a melt‐polymerization technique carried out in a twin‐screw, vacuum‐vented extruder. Low molecular weight polymer, polymerized in a conventional melt reactor, was further polymerized to copolyesters with intrinsic viscosities, under the conditions investigated, of up to 0.76 dl/g. The optimum extruder reaction conditions with respect to temperature profile, vent configuration, and polymer throughput are described. A variety of properties for two representative copolyester compositions have been determined. Particular attention was given to melt viscosity and impact strength, two properties which depend markedly on whether the polymer is prepared by the subject melt process or, alternately, by a low temperature interfacial polycondensation. It is concluded, based on a study of deliberately branched, interfacially prepared copolyesters, that the property differences which depend on the polymerization method are attributable to the formation of branches in the copolyesters prepared by the high‐temperature melt process.
Ionic graft copolymerization. VI. Graft copolymerization of β‐propiolactone and N‐vinylcarbazole onto trunk polymer containing carboxylic acid, sulfonic acid, and their salts
Authors: Shiota Tetsuya , Goto Yutaka , Hayashi Koichiro , Okamura Seizo
Published: April 2003

It was pointed out in previous papers that both cationic and anionic polymerization might be involved simultaneously in grafting onto trunk polymers containing COOH or SO3Na. The graft copolymerization of β‐Propiolactone (βPL)–N‐vinylcarbazole (NVCZ) onto styrene‐divinylbenzene copolymers containing carboxylic acid, sulfonic acid, and their salts was carried out in order to distinguish between the polymers produced by anionic and cationic mechanisms. The polymer obtained by the polymerization of βPL–NVCZ with BF3·OEt2, a typical cationic catalyst, consisted mainly of NVCZ units, but the polymer obtained with BuLi, a typical anionic catalyst, consisted mainly of βPL units. In the graft copolymerization of NVCZ–βPL onto trunk polymer containing COOH, the NVCZ contents of the branch polymer and the tolueneinsoluble fraction were estimated to be ca. 50 mole‐%; therefore these polymers were produced by both cationic and anionic mechanisms. In the case of graft copolymerization onto the trunk polymer containing SO3Na, it was found that both cationic and anionic polymerization also occurred simultaneously.
Thermal degradation of perfluoropolyphenylenes
Authors: Cotter J. L. , Knight G. J. , Lancaster J. M. , Wright W. W.
Published: April 2003

The thermal degradation of meta‐ and para‐linked perfluoropolyphenylenes in vacuo and in oxygen has been studied. Rates of breakdown were determined thermogravimetrically and products of breakdown in vacuum analyzed by using a mass spectrometer. The thermal stability in vacuo was comparable with that of polyphenylene, and that in oxygen was rather inferior to that of polytetrafluoroethylene. The higher molecular weight polymers gave as the main volatile degradation products silicon tetrafluoride and carbon dioxide, together with a carbonized residue containing virtually no fluorine.
The effect of structural changes on dye diffusion in poly(ethylene terephthalate)
Authors: Dumbleton J. H. , Bell J. P. , Murayama T.
Published: April 2003

The diffusion of a disperse dye, 1‐amino‐4‐hydroxyanthraquinone (C.I. Disperse Red 15) into poly(ethylene terephthalate) fibers has been studied as a function of heatsetting temperature and draw ratio. It was found that the dynamic loss modulus E″, measured under the dyeing conditions, was related to the dye diffusivity D. This indicates that the diffusion is controlled by the mobility of the polymer chain segments. Both the diffusivity and dye saturation values do not vary monotonically with heatsetting temperature but exhibit a minimum at a heat‐setting temperature near 175°C. X‐ray diffraction measurements were used to show that this behavior is attributable to crystallinity and crystal size changes resulting from heat‐setting.
Crosslinking reaction of rubber with aldehydes
Authors: Minoura Yuji , Tsukasa Masahiro
Published: April 2003

The reactions of rubber with aldehydes have previously been studied in latex or in solutions and the reaction products formed by cyclization, condensation, or addition, have been reported. In the present study, solid‐state reactions of rubber with aldehydes were carried out. It was found that crosslinked rubbers may be obtained by press curing in the presence of aldehydes with acidic catalysts. Polychloroprene and Hypalon especially undergo these reactions without a catalyst or with a small amount of catalyst. In the experiments using various aldehydes, some improvements in the properties of the crosslinked rubber were observed when aldehydes such as paraformaldehyde or α‐polyoxymethylene were used. Some Lewis acids such as SnCl2·2H2O were found to be more effective catalysts than the above, and it was found that organic acids such as p‐toluenesulfonic acid could also be used. The curing seemed to be an ionic reaction. The physical properties of the crosslinked rubber are similar to these of sulfur‐cured rubbers.
Structure and properties of cellulose graft copolymers. II. Cellulose–styrene graft copolymers synthesized by the ceric ion method
Authors: Huang Robert Y. M. , Chandramouli P.
Published: April 2003

Styrene was graft‐copolymerized onto wood cellulose by the ceric ion method of Mino and Kaizerman. The grafting reaction was found to depend strongly on the concentration of ceric ion in the grafting system and maximum grafting occurred in a narrow range of concentration of initiator, 1.0 × 10−3‐1.8 × 10−3 mol/l, at 58 ± 1°C. A pretreatment technique, developed to enhance the monomer diffusion into cellulose, was found to increase the grafting considerably. The structures of the cellulose‐styrene graft copolymers were studied by hydrolyzing away the cellulose backbone to isolate the grafted polystyrene branches. The molecular weight and the molecular weight distributions of the grafted polystyrene were determined using gel permeation chromatography. The number‐average molecular weight (M̄n) ranged from 23,000 to 453,000 and the polydispersity ratios (M̄w/M̄n) varied from 2.5 to 8.0. The grafting frequencies calculated from the per cent grafting and molecular weight data were of the order of 0.05–0.4 polystyrene branches per cellulose chain.
Time–temperature dependent brittle fracture of viscoelastic solids
Authors: Olear P. D. , Erdogan F.
Published: April 2003

The Griffith formulation is used to study fracture behavior of poly(methyl methacrylate) (PMMA) as a function of strain rate and temperature over the range 4.4 × 10−5 ≤ ε ≤ 4.4 × 10−2 in./in./sec and 25°C ≤ T ≤ Tg, Tg being the glass transition temperature. It is found that the transition from brittle to ductile failure occurs abruptly at a temperature Tf which is dependent on strain rate and is approximately the same as the glass transition temperature of the material. The Griffith brittle fracture criterion is found to apply below Tf for all strain rates. The brittle fracture behavior is shown to obey the time–temperature equivalence principle in the same way as the material's other viscoelastic properties, having the same shift function.
Effect of plasticizers on the viscoelastic properties of poly(vinyl chloride)
Authors: Hata N. , Tobolsky A. V. , Bondi A.
Published: April 2003

Stress relaxation modulus data, Er(t), have been determined between −70 and +170°C on blends of three samples of poly(vinyl chloride) of different molecular weights with di‐2‐ethylhexyl adipate, di‐2‐ethylhexyl phthalate, epoxidized soybean oil, and a poly(propyl adipate), respectively. The relaxation modulus‐time–temperature data could be combined into master curves. However, probably owing to the finite contributions of the crystalline phase to the elastic properties, time–temperature superposition is here just marginally valid, and the master curves are only crude, yet still useful approximations. Combination of the present data with the accumulated published information suggests that the viscoelastic properties of plasticized poly(vinyl chloride) are determined primarily by the glass transition temperàture of the plasticizer, the compatibility of polymer and plasticizer, and probably also by the crystallites (as crosslinks). The exact role of the crystallites will remain elusive until the advent of plasticized poly(vinyl chloride) with controlled crystallinity.
Separation of liquid mixtures by using polymer membranes. I. Permeation of binary organic liquid mixtures through polyethylene
Authors: Huang Robert Y. M. , Lin Victor J. C.
Published: April 2003

The permeation characteristics and the separation behavior of 25 combinations of binary liquid mixtures through low‐density polyethylene membrane have been investigated. The organic compounds studied were members of the homologous series of liquid aliphatic hydrocarbons between n‐pentane and n‐nonane as well as some aromatic and cyclic compounds. A special permeation cell was designed in order to study permeation rates at different temperatures ranging from 25 to 45°C. The rate of permeation increased with temperature, and it was found that the temperature dependence of the permeation rate for both pure compounds and mixtures could be expressed by Arrheniustype relationships. The efficiency of separation, however, decreased with increasing temperature. Activation energies of permeation rànged from 16–22 kcal/mol for pure compounds and binary mixtures of benzene, n‐hexane, cyclohexane, and 2–2‐dimethylbutane. The effects of chemical nature, molecular size, and molecular shape of the diffusing species on the permeation and separation were studied and qualitative guidelines were suggested. The effect of the composition of the binary mixtures on the permeation rate has been investigated for several systems. Permeation enhancement effects were observed in which the mixtures permeate considerably faster than either of the pure components. Maximum permeation rates occurred at about 50 wt‐% mixtures for the systems benzene–n‐hexane and benzene–cyclohexane. This phenomenon is explained in terms of a combined internal plasticizing and solubility effect.
Permeability studies on heterogeneous polymer films
Authors: Peterson Clarke M.
Published: April 2003

Oxygen permeability data on heterogeneous films prepared from mixtures of different polymer latices were compared with predictions of a permeability theory of Higuchi based on an idealized barrier model. The theory attempts to evaluate the effect of perturbations of the diffusion process associated with the presence of a discontinuous internal‐phase component. An approximate form of the theoretical permeability expression was found to render reliable predictions of the effective permeability of heterogeneous barrier systems. When the partition of the permeant between different phases of the barrier is sufficiently rapid, the theory becomes applicable to the early, nonsteadystate, stage of permeation. Implications of the general applicability of the Higuchi theory to heterogeneous systems are discussed with respect to the interaction between the constitutents and the associated departures from the ideal behavior assumed for the model.
A simplified gas permeability apparatus
Authors: Peterson Clarke M.
Published: April 2003

A simplified gas permeability apparatus is described which is used in performing the essential functions of more complex conventional designs. An improved diffusion cell clamp is described, and the basic operation of the instrument is outlined. Experimental data are submitted as evidence of the reliability of the instrument.
Piezoelectricity, pyroelectricity, and thermoelectricity of polymer films
Authors: Furukawa Takeo , Uematsu Yutaka , Asakawa Kiyoshi , Wada Yasaku
Published: April 2003

Some electrical phenomena in amorphous and partially crystalline polymers are studied. The phenomena are phenomenologically similar to those in crystalline materials, but their origin is concluded to be space charges embedded in polymers. Voltage is induced across the surfaces of polymer films, i.e., polystyrene, poly(methyl methacrylate), polyethylene, and polypropylene, when they are vibrated in elongation (elongational piezoelectricity) and in bending (bending piezoelectricity). The former is attributed to a space charge distribution which is antisymmetrical about the median plane of the film and the latter to symmetrical distribution. A general description of piezoelectricity of a system in which space charge is embedded in homogeneous continuum is developed. Output current from poly(vinyl chloride) films at high temperatures (above 125°C) was measured under the following conditions: (1) under potential gradient (electrical conduction), (2) under temperature gradient (thermoelectricity), and (3) when the film is uniformly heated (pyroelectricity). Pyroelectricity is attributed to drift of space charge to electrodes on account of electrostatic force by image charge. Depolarization current of a poly(vinyl chloride) film which has been polarized at 125°C prior to measurement (electret) is interpreted in terms of dipole disorientation plus space charge drift.
Morphology of man‐made fibers
Authors: Van Veld R. D. , Morris G. , Billica H. R.
Published: April 2003

Recent advances in electron microscopy of polymer systems have produced new structure theories (lamellar versus micellar) and considerable speculation on the nature of synthetic fiber structure. This paper illustrates what can be seen directly on the structure of nylon 66, polyester, and acrylic fibers with high‐resolution and scanning electron microscopy and attempts to relate the structure seen in the complex fiber systems with simpler structure observed in bulk polymer and solution grown crystals. Instances of support for the lamellar and fibrillar theories of structure are noted.
Radical polymerization of N‐vinylcaprolactam in homogeneous solution. II
Authors: Solomon O. F. , Vasilescu D. S. , Tǎrǎrescu V.
Published: April 2003

The polymerization of N‐vinylcaprolactam in toluene, dioxane, chlorobenzene, dimethylformamide, and ethylene carbonate with various peroxides, perbenzoates and azobisisobutyronitrile as initiators at 60–80°C, was studied. Under these conditions azobisisobutyronitrile and tert‐butyl perbenzoate have satisfactory activity as initiators. Under these conditions N‐vinylcaprolactam polymerization in homogeneous solution is first order towards the monomer and 0.5 order towards the initiators.
Estimation of rate constants during polypropylene autoxidation
Authors: Reich Leo , Stivala S. S.
Published: April 2003

Recently, Chien and Boss calculated rate constants for the autoxidation of isotactic polypropylene based upon a postulated relatively simple scheme. Electron spin resonance, volumetric, and chemical techniques were employed. It behooved the authors of this paper to demonstrate that similar values of these rate constants could also be calculated from a more general scheme. From this general scheme, expressions were derived which involved the rate constants of interest and other constants which had been previously calculated from experimental data based upon the use of infrared absorption techniques. The values of our calculated rate constants at various temperatures agreed well with those reported by Chien and Boss where comparison was possible.
Swelling of cotton in alkalis and acids
Authors: Warwicker J. O.
Published: April 2003

A study of the swelling of Acala 4‐42 cotton in aqueous alkalis and acids has been carried out. The degree of swelling of the cotton in the reagents has been indicated by measurement of the variations in width of the cotton at its widest point. The nature of the swelling process whether interfibrillar or intrafibrillar has been deduced from microscopical and x‐ray evidence. It has been shown that a similarity of shape of the swelling curves, i.e., an equal degree of swelling in the same or other reagents, does not imply the same mechanism of swelling. The results are more readily explained in terms of the crystalline‐fibril theory than by the fringe‐micellar theory, especially when high degrees of swelling have been achieved.
High‐temperature mechanical behavior of PVC: A comparison of suspension‐ and emulsion‐prepared polymers
Authors: Crugnola A. , Zoppi F. , Moraglio G.
Published: April 2003

We have investigated the high temperature mechanical behavior of several unplasticized emulsion‐ and suspension‐prepared whole polymers, and carried out molecular weight, molecular weight distribution, and branching characterization studies on these same materials. It is concluded that the easier workability of the emulsion product is probably due to the absence of a considerable amount of high molecular weight polymer in these as compared to suspension‐prepared polymers of equal average molecular weight as reflected by intrinsic viscosity determinations of Fikentscher K values.
Calcium stearate–stearic acid as lubricants for rigid poly(vinyl chloride) (PVC). Capillary rheometer measurements and extrusion properties
Authors: Fredriksen Odd
Published: April 2003

Capillary rheometer measurements show that stearic acid can be characterized as a normal lubricant. If the content of stearic acid is increased in rigid PVC formulations, the melt viscosity will decrease. This leads to a corresponding increase of shear rate and volumetric flow rate. The influence of calcium stearate is opposite to the normal characteristic of a lubricant. Increasing amounts of calcium stearate lead to an increased melt viscosity and a decreased shear rate and volumetric flow rate. In the extrusion of rigid PVC, the apparent “lubricating” effect of calcium stearate is probably due to the increased friction with resulting heat evolution and higher mass temperature, leading to a decreased viscosity of the plastic melt. This is in agreement with the results of the extrusion experiments. Both mass temperature and power consumption decrease when stearic acid is added and increase when calcium stearate is added to the formulation.
Reaction of SO2 and NO2 with polymers
Authors: Jellinek H. H. G. , Flajsman F. , Kryman F. J.
Published: April 2003

A number of polymers have been exposed to SO2 and NO2 gas under various conditions. Chain scission, crosslinking reactions, and changes in infrared spectra have been noted. All polymers suffer some deterioration, which may be considerable with exposure over long periods of time. Elastomers form a separate group, being appreciably more susceptible to these gases than saturated polymers; however, they are still more sensitive to ozone.
Viscosities of moderately concentrated solutions of polyethylene in ethane, propane, and ethylene
Authors: Ehrlich Paul , Woodbrey James C.
Published: April 2003

The viscosities of moderately concentrated solutions of low‐density polyethylenes in ethane, propane, and ethylene have been measured at low shear rate in the temperature range of 150–250°C and in the pressure range of about 15000–30000 psi. Within the precision of the measurements, the relative viscosity is independent of pressure over the range investigated but increases as the solvent is changed from propane through ethane to ethylene. The activation energy for the relative viscosity in ethane varies from about 0.5 to 2.5 kcal/mole as the concentration changes from 5 to 15 g/dl. Effects of polymer concentration and molecular weight on solution viscosity in ethane at 150°C have been determined, and all of the data can be represented by a single straight‐line plot of the logarithm of relative viscosity versus the intrinsic viscosity (in p‐xylene at 105°C) times concentration. This simple relation is valid over wide ranges of polymer concentration and molecular weight and over more than two orders of magnitude of relative viscosity. The solution viscosities of the polyethylenes in the three supercritical fluid solvents used appear surprisingly low at first sight. This behavior is partly a result of the low solvent viscosities but also might mean that the polymer has an abnormally low segmental friction factor compared to that in solutions under more familiar conditions.
Solubilization of calfskin collagen in citrate buffer with the use of automated equipment
Authors: Kahn Leo D. , Witnauer Lee P.
Published: April 2003

An automated collagen solubilizing apparatus that maintains constant electrolytic conditions during solubilization is described. It was used in solubilization of 6.95% of a calfskin corium as monomeric collagen in citrate buffer at pH 3.44 and ionic strength of 0.44 and a temperature of 8°C. It is shown that this is the limit of solubilization for undenatured collagen in this buffer.
Structure and properties of extruded polyethylene film
Authors: Desper C. Richard
Published: April 2003

A series of low‐density polythylene extruded films was examined quantitatively by the birefringence, infrared dichroism, and x‐ray pole figure techniques. The birefringence ranges from mildly positive to mildly negative with increasing severity of quenching conditions. The x‐ray data show that the birefringence is largely due to the contribution of oriented crystallites, the amorphous orientation being quite low. The crystal orientation functions suggest equal degrees of a and c axis orientation parallel to the machine direction at low quenching rates, and increasing a axis orientation as the quenching rate increases, coupled with a shift in the c axis from parallel to perpendicular orientation. These results are confirmed by infrared dichroism data. The relative degree of a and c axis orientation ultimately reached is intermediate between that predicted by Keller's type I and type II models, but approximates the orientation previously observed in laboratory films prepared by oriented crystallization at 100% elongation. The crystalline orientation may be explained by the modified row orientation structure of Keller and Machin. However, the data can also be reconcilled with that of spherulitic entities observed in samples crystallized at 20‐50% stretch. It is suggested that these spherulites may possess a combination type II and screw dislocation morphology in the equatorial and polar regions, respectively. Such a structure differs from the row structure in that the latter implies that the amount of polar material is negligible compared to the equatorial material. It is recognized, however, that orientation data cannot unambiguously decide between these alternatives.
Disubstituted p‐phenylene monomers. α‐methyl‐ and α‐phenyl‐vinyl derivatives of benzene, biphenyl, p‐terphenyl, and p,p′‐diphenoxiybiphenyl
Authors: Rosser Robert W. , Neville Roy G.
Published: April 2003

The high‐yield syntheses of bis [p‐(α‐methylvinyl)] monomers of benzene, biphenyl, p‐terphenyl, and 4,4′‐diphenoxybiphenyl are reported. Also described are the syntheses of new bis[p‐(α‐phenylvinyl)] monomers of biphenyl, p‐terphenyl, and 4,4′‐diphenoxy‐biphenyl. Infrared spectral data for the diolefinic monomers and their precursors are presented, together with brief details for the polymerization of the diolefins by means of free radical and Lewis acid catalysts.
Studies on dry spinning. I. Fundamental equations
Authors: Ohzawa Yoshiyuki , Nagano Yutaka , Matsuo Tatsuki
Published: April 2003

One difficulty in analyzing the state of filament in the dry spinning process is that in the boundary conditions required to solve the equations of mass, momentum and energy which are derived on the consideration of balance with respect to infinitesimally small element are not given a priori. The equations which include these boundary conditions in themselves are derived by considering mass, momentum, and energy balances with respect to the entire cross section of filament. These additional macroscopic equations are simplified to a great extent by assuming the flat velocity profile through the cross section of filament. Besides, in the steady state, these macroscopic equations are modified to give the equations of average solvent content, spinning tension, cross‐sectional area, and average temperature. When the spinning conditions are given and the physical constants are measured for a given polymer and solvent system, it becomes possible to calculate the state of filament by solving these microscopic and macroscopic equations simultaneously without resorting to actual spinning.
Influence of molecular weight distribution on the elasticity and processing properties of polypropylene melts
Authors: Mieras H. J. M. A. , Van Rijn C. F. H.
Published: April 2003

In a study of the flow behavior of polymer melts a semi‐empirical viscometric equation has been used which contains an elasticity parameter relating the shear dependence of the viscosity to the normal‐stress effect. The way in which both these effects are influenced by the molecular weight distribution of the polymers investigated is shown, and the influence of melt elasticity on polymer processing behavior is discussed. From previously published viscosity data the elasticity parameter has been determined for a number of polypropylene grades, and the possibility of classifying these grades according to a characteristic time constant is indicated.
Adhesion behavior of nylon tire cord/adhesive/rubber systems
Authors: Iyengar Y.
Published: April 2003

In static and dynamic adhesion tests, the behavior of nylon tire cord/resorcinol‐formaldehyde–latex (RFL) adhesive/rubber systems was shown to be strongly influenced by the dipping and curing conditions, cord size, and the thickness of rubber layer adjacent to cords. The nature and extent of these effects were different in three types of adhesion tests which differed in stress concentrations they induced at the cord–rubber interface. The influence of stress concentration due to increased cord size was clearly seen in dynamic adhesion tests where the peel strengths of two‐ply cord/rubber samples were measured after flexing them under tension over a pulley for predetermined periods at 230°F. In these tests, the adhesion of samples with large cords weakened more rapidly than that of small cords. The static adhesion level attained with nylons 6 and 66 and other polyamide fibers was strongly dependent on the conditions (time, temperature) under which the RFL adhesive was applied and cured. At any given exposure, adhesion initially increased rapidly with the RFL curing temperature and attained a maximum above a temperature which is characteristic of the polyamide. For nylon 66, optimum adhesion was attained with different combinations of RFL curing temperatures (390–460°F) and times (20–120 sec). Finally the adhesion of nylons 6 and 66 is discussed from thermodynamic considerations based on entropy change.
Ethylene‐propylene terpolymers with conjugated double bonds
Authors: Sonnenfeld R. J. , Kahle G. R. , Buck O. G.
Published: April 2003

A study was made of ethylene‐propylene terpolymerization with fulvenes and various acetylenes. Vinylacetylene, 2‐methyl‐1‐buten‐3‐yne (isopropenyl‐acetylene) or 6,6‐dimethylfulvene in conjunction with ethylene and propylene formed terpolymers which contained conjugated double bonds. The presence of conjugated double bonds was established by infrared and ultraviolet analyses. The terpolymers were randomly unsaturated with sufficient unsaturation to be sulfur‐vulcanized.
Analysis of the volatile combustion products of vinyl plastics
Authors: Boettner E. A. , Ball Gwendolyn , Weiss Benjamin
Published: April 2003

The extensive use of plastics for insulation and building materials has created interest in the possible toxicity of their combustion products. Three poly(vinyl chloride) homopolymers, a vinyl chloride‐vinyl acetate copolymer, and formulations of two of the homopolymers and the copolymer have been examined to determine the composition and toxicity of their combustion products. Differential thermal analysis and thermal gravimetric analysis were used to study the breakdown process which occurred in several steps, the largest and first being the release of hydrogen chloride from the polymer at about 300°C. Approximately 50 products of combustion were then determined qualitatively by using either infrared spectroscopy or a combination of gas chromatography and mass spectroscopy. Quantitative analyses were carried out on 22 of the combustion products, and quantitative changes with varying air supply, temperature, and heating rate were determined. A comparison of the products of the polymers and their formulations is given.
Thermal degradation of polymers. II further thermogravimetric and differential thermal analysis studies of atactic poly(m‐aminostyrene) homopolymers, copolymers, and related polymers
Authors: Still R. H. , Jones P. B. , Mansell A. L.
Published: April 2003

Thermogravimetric and differential thermal analysis have been employed to study the effect on the thermal degradation pattern in static air of the molecular weight of poly(m‐aminostyrene) homopolymers and copolymers with styrene. Related substituted styrene polymers and copolymers with styrene have also been studied in order to assess the effect of introduction of amino, substituted amino, and hydroxy groupings into a polystyrene main chain. The effect of these groupings on the thermal stability of the polymers as compared with polystyrene suggests that the inherent antioxidant characteristics of the subtituent grouping plays the major role in stabilization. A molecular weight effect has been shown to be operative for m‐aminostyrene, p‐N,N‐dimethylaminostyrene, and m‐hydroxystyrene polymers. This manifests itself in terms of different thermograms rather than by significantly influencing the procedural decomposition temperatures, although a trend is seen.
The determination of the isotacticity of polypropylene in the 90–100% range by infrared spectroscopy
Authors: Hughes Richard H.
Published: April 2003

An infrared method has been developed for the determination of the isotacticity of polypropylene in the 90–100% range. The method requires the annealing of thin films at 165–167°C. for 3 hr. in an inert atmosphere, followed by slow cooling to room temperature. For approximate answers the ratio of the intensity of the 10.00 μ band to that of the 10.27 μ band can be reported as the fraction of isotactic material. Better results are obtained, however, by using Figure 2 as a calibration curve and reading the values from it.
Kinetics of contraction of drawn nylon 66 in aqueous phenol
Authors: Jacobs Martin I. , Rebenfeld Ludwig , Taylor Hugh S.
Published: April 2003

The rate of contraction of drawn nylon 66 in aqueous phenol was investigated, and a method is described for correlating this contraction with a series of elementary rate processes. The rate constants so obtained were analyzed by absolute rate theory, and the variations of ΔH† and ΔS† with phenol concentration gave evidence of the nature of the reaction steps.
Flex life and long‐term strength of composite materials
Authors: Fulmer Glenne E. , Guthrie James L.
Published: April 2003

The relationship is shown between the flex life and long‐termtensile strength of flexible composite material. The long‐term strength is interpreted in terms of a kinetic theory of failure. However, it is not posible to predict the flex life from tensile strength or even long‐term strength data unless the stiffness or modulus is considered along with the thickness of the sample. With these factors it becomes possible to predict the flex life of a material and to compare various flex‐testing instruments utilizing a new concept, which material and to compare various flex‐testing instruments utilizing a new concept, which we call “effective force.” The usefulness of the concept of effective force is explained.
Allylic polymers. Diallyl 2‐substituted succinate prepolymers and their properties
Authors: Nowlin G. , Gannon J. A. , Jungster L.
Published: April 2003

Diallyl 2‐substituted succinates, obtainable via the addition of alkenes or alkylaromatics to maleic anhydride, undergo intramolecular cyclization during polymerization to low molecular weight prepolymers. The amount of this cyclization and the properties of the cured prepolymers are profoundly affected by the structure of these 2‐substituents. Thus, the degree of cyclization decreases with these substituents in the order: aralkyl and isobutyl > unhindered alkenyl > alkyl > hindered alkenyl. Properties of thermosetting molding compounds based on these prepolymers are inferior to those of poly‐(diallyl phthalate) molding compounds.
Analysis of condensation polymerization reactors. I. Kinetic model
Authors: Szabo T. T. , Leathrum J. F.
Published: April 2003

A mathematical model for the kinetics of polycondensation reactions was developed. Reaction rates were expressed in terms of reactive functional groups where the reactivity of each functional group was assumed to be independent of the size of the polymer molecule. A method of testing the validity of the model with batch reactor data is demonstrated. The model is then employed to derive expressions for the equilibrium constant and molecular weight distributions. Continuous reactor yields and molecular weight distributions are then predicted from the batch reactor data. The reactions considered include chain growth, scission, and ester exchange reactions.
A method of measuring tackiness
Authors: Kambe Hirotaro , Kamagata Kazuo
Published: April 2003

For measuring the tackiness of viscous materials to the solid surface, we designed an attachment to the tensile tester driven with constant speeds. Blends at high molecular weight polyisobutylene with low molecular weight polyisobutylene or with a hydrogenated rosin were used as samples. The maximum force fb at the time tb of the force‐time relation recorded on a chart was determined as a measure of the tackiness. The relation between fb and tb satisfies the equation fb ∝ tb−1/2 derived by Eley. The fb depends on the time tc and the pressure pc at contact, the temperature and the rate of sepration, r, and the rosin content of the sample. The activation energy, obtained from the slope of plots of fb against the reciprocal of the absolute temperature shows a value of 2–6 kcal/mole, which is similar to the activation energy of the viscous flow. To decide whether the failure occurs at the interface or within the adhesive itself, fb was measured with cylinders made of various materials such as polytetrafluoroethylene, polyethylene, poly(methyl methacrylate), and brass.
Radiation‐crosslinked polypropylene: Physical and dielectric properties
Authors: Benderly Asaf A. , Bernstein Bruce S.
Published: April 2003

Irradiation of two stereoregular polypropylenes and a polyallomer via 60Co in the presence of 3–8% allyl methacrylate (AMA) monomer, to does up to 5 Mrad, lead to an improvement in mechanical properties. With irradiation, heat resistance, tensile strength, and gel fractions increased, and creep compliance decreased. The decrease in creep compliance was revealed by measurements of irradiated samples at 1850C (at constant load and monomer level), a temperature above the Tm of polypropylene. Dielectric properties (dielectric constant K and dissipation factor tan δ) were virtually unaffected by irradiation of 0.3 to 5.0 Mrad in nitrogen when AMA was absent. In the presence of monomer, small but generally tolerable increases in tan δ resulted if the monomer concentration was not too great. To obtain improvements in mechanical properties while not simultaneously altering the dielectric losses, it was necessary to keep the AMA concentration to a maximum of 4%.