bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of molding conditions on properties of injection‐molded polycarbonates
Authors: Koda Hiroyuki 
Published: April 2003

AbstractStatistically 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

AbstractThe 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

AbstractSix 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

AbstractIonic 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

AbstractThe 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

AbstractThe 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

AbstractHigh 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

AbstractIt 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

AbstractThe 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

AbstractThe 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

AbstractThe 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

AbstractStyrene 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

AbstractThe 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

AbstractStress 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

AbstractThe 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

AbstractOxygen 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.
Piezoelectricity, pyroelectricity, and thermoelectricity of polymer films
Authors: Furukawa Takeo , Uematsu Yutaka , Asakawa Kiyoshi , Wada Yasaku 
Published: April 2003

AbstractSome 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

AbstractRecent 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

AbstractThe 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

AbstractRecently, 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

AbstractA 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

AbstractWe 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.