bluuebunny/crossref_metadata_2025 huggingface dataset:
Crystallization kinetics of poly‐ε‐caprolactone from poly‐ε‐caprolactone/poly(vinyl chloride) solutions
Authors: Robeson Lloyd M.
Published: April 2003

The polymer–polymer solution of poly(vinyl chloride) and poly‐ε‐caprolactone yields an excellent system for studying the crystallization kinetics of a crystallizable component from a polymer–polymer solution. Unlike previous studies of isotactic–atactic polystyrene solutions for which the glass transition temperature is invariant with composition, this system exhibits a marked dependence of Tg on the composition. The experimental data dE⅓(modulus)/dt (psi⅓/min) were obtained over a composition range of 40 to 70 wt‐% poly‐ε‐caprolactone. With the appropriate modification of the spherulitic growth rate equation, the expression

approximated a reasonable fit of the experimental data. This demonstrates a marked dependence of the crystallization rate on concentration. Secondary observations of this investigation show a slower crystallization rate for high molecular weight poly‐ε‐caprolactone and a slow secondary crystallization step. Both homopolymer poly‐ε‐caprolactone and poly‐ε‐caprolactone in the poly‐ε‐caprolactone/poly(vinyl chloride) solution show a slow (relative to the nucleation‐controlled step) crystallization stage considered to involve a slow diffusion mechanism.
Molecular weight decrease in the early pyrolysis of crystalline and amorphous cellulose
Authors: Broido A. , Javier‐Son A. C. , Ouano A. C. , Barrall Edward M.
Published: April 2003

Samples of ordinary “ash‐free” cellulose papers and similar samples decrystallized by swelling in liquid ammonia were pyrolyzed in vacuo to a weight loss ranging from <0.1% to nearly 20%. The samples were then nitrated and their molecular weight distributions determined by gel permeation chromatography. When weight loss reached 1%, both the ordinary and the ammonia‐swelled celluloses showed a large drop in average degree of polymerization (D.P.). However, the ordinary cellulose showed this sharp drop long before there was any measurable weight loss; the ammonia‐swelled cellulose changed D.P. only gradually in the early stages. Further, x‐ray diffraction measurements showed that by the time the D.P. of the ammonia‐swelled cellulose had dropped appreciably, the material had developed a significant crystalline pattern. These results support the suggestion that initial rupture of the cellulose molecule occurs at strain points at the crystalline–amorphous boundaries.
On the dynamics of melt spinning
Authors: Cernia E. , Conti W.
Published: April 2003

The dynamics of melt spinning was examined in the case of a Lethersich liquid taking also into account a phenomenologic way as well the transition zone between shear and elongational flow. The shape of the fluid jet was measured under many spinning conditions; the filament temperature and the fluid viscosity were then calculated. The experimental viscosity temperature relationship was compared with the W. L. F. equation, and the comparison makes it clear that the Newtonian model is not adequate whereas all the experimental evidence is in qualitative accordiance with the proposed model.
Preparation of fine powdery copolymer with crosslinkage and monoalkyl maleate unit
Authors: Mizutani Yukio , Matsuoka Seishiro , Iwasaki Masatoshi , Miyazaki Yoshimichi
Published: April 2003

In order to prepare fine powdery and crosslinked copolymer as a foaming agent and a modifier for polypropylene, the following processes were investigated: (1) polymerization of monoalkyl maleate–styrene–divinylbenzene; (2) polymerization of monoalkyl maleate–maleic anhydride–styrene–divinylbenzene; (3) polymerization of maleic anhydride–styrene–divinylbenzene and esterification of the copolymer with methanol, and (4) polymerization of maleic anhydride–styrene–divinylbenzene in the presence of methanol. The thermal treatment of copolymer thus obtained and the foaming ability for polypropylene were then investigated.
Reverse osmosis separation of hydrocarbons in aqueous solutions using porous cellulose acetate membranes
Authors: Matsuura Takeshi , Sourirajan S.
Published: April 2003

A physicochemical parameter, represented by the symbol Σs*, based on molar solubility in water and molar attraction constants of Small, has been developed to express quantitatively the relative hydrophobicity, or nonpolar character, of the hydrocarbon molecule. The value of Σs* can be calculated for a hydrocarbon from its chemical structure. The scale of Σs* is consistent within each group of aromatic, cyclic, and noncyclic hydrocarbons. Reverse osmosis data have been obtained at 250 psig for single‐solute aqueous feed solution systems involving low concentrations of 39 different hydrocarbons (including 13 aromatics, 10 cyclic, and 16 noncyclic compounds) and several samples of cellulose acetate membranes of different surface porosities. The effect of operating pressure on membrane performance has also been studied for two aromatic hydrocarbon solutes. The values of Σs* for the solutes used were in the range of 425 to 924 for aromatic hydrocarbons, 521 to 931 for cyclic hydrocarbons, and 369 to 960 for noncyclic hydrocarbons. The reverse osmosis data have been correlated with Σs* for each group of hydrocarbons studied. In all cases, positive solute separations were obtained, and the ratio [PR]/[PWP] was less than 1. With respect to each film, solute separation increased with increase in Σs*, and decreased with increase in operating pressure. Also, solute separation decreased in the order aromatic hydrocarbon > cyclic hydrocarbon > noncyclic hydrocarbon at any given value of Σs*. At a given operating pressure, for low values of Σs* (∼500 or less) solute separation increased with progressive decrease in average pore size on the membrane surface. For high values of Σs* (∼800 or more), solute separation initially increased with decrease in average pore size, then passed through a maximum and minimum with further decrease in average pore size, and again increased with still further decrease in average pore size. The results are discussed on the basis of preferential sorption of solute at the membrane–solution interface under the experimental conditions studied.
The formation of translucent cold‐drawn polypropylene
Authors: Lee C. , Uhlmann D. R.
Published: April 2003

The behavior of quenched samples of polypropylene subjected to stress relax–reload cycles during cold drawing has been investigated as a function of quench severity and strain rate. Results obtained by cooling the propagating neck of a drawing sample are also discussed. A translucent cold‐drawn form of the polymer, characterized by a small microvoid content, is observed when the propagating neck boundary is cooled or when stress relax–reload cycles are carried out at sufficiently high strain rates. A small mobility of the chains relative to the local strain rate is postulated as necessary for the formation of the translucent material.
Diffusion in polyelectrolyte solutions
Authors: Griskey Richard G. , Sedahmed G. H.
Published: April 2003

Diffusion in polyelectrolyte solutions was studied. The mass transfer was determined by an electrochemical technique which involved transport from the fluid to the tube wall. It was found that diffusion behavior depended on the ionic nature of the diffusing species. Neutral molecules showed an increase in diffusion coefficients. This was apparently due to both solvation of solvent molecules and extension of polymer molecules. Ionic diffusing species showed a decrease in diffusion coefficients. The greater the ionic strength, the greater the decrease. The effect was most likely due to ionic interaction with the polyelectrolyte molecules.
Degradation of thin films of a fluoropolymer
Authors: Tompkins Harland G.
Published: April 2003

1H‐1H‐Pentadecafluorooctyl methacrylate, a fluoropolymer, is used as a barrier coating to control spreading of thin liquid films, notably silicone oil. Using infrared spectroscopy and thermogravimetric analysis, this work describes the thermal degradation of thin films of this fluoropolymer. The conclusions are that the degradation is a two‐stage, thermal bond‐breaking phenomenon which does not required an additional reactant such as oxygen or water vapor. Rate constant data are presented for both stages of the degradation.
Isothermal transitions of a thermosetting system
Authors: Gillham J. K. , Benci J. A. , Noshay A.
Published: April 2003

A study of the curing reactions of a cycloaliphatic epoxy resin/anhydride system by torsional braid analysis showed the existence of two critical isothermal temperatures. These are Tg∞ (the maximum glass transition temperature of the thermoset system) and Tgg (the glass transition temperature of the material at its gel point). Two rheologically active kinetic transitions occur during isothermal cure which correspond to gelation and vitrification. Three types of isothermal behavior occur: if Tcure > Tg∞, only gelation is observed; if Tg∞ > Tcure > Tgg, both gelation and vitrification are observed; if Tcure < Tgg, only vitrification is observed. Tgg corresponds to the isothermal cure temperature at which gelation and vitrification occur simultaneously. Methods for determining the time to gel and the time to vitrify, and also Tg∞ and Tgg, have been developed. The time to gel obeyed the Arrhenius relationship, whereas the time to vitrify passed through a minimum. Application of these results to thermosetting systems in general is discussed in terms of the influence of molecular structure on the values of Tg∞ and Tgg.
Studies on polymer blend of nylon 6 and polypropylene or nylon 6 and polystyrene using the reaction of polymer
Authors: Ide Fumio , Hasegawa Akira
Published: April 2003

In the presence of maleic anhydride‐grafted polypropylene, marked dispersibility of the polymer blend of isotactic polypropylene and nylon 6 was obtained. This appeared to be caused by the formation of a certain graft polymer between maleic anhydride in polypropylene and terminal amino groups of nylon 6. The same phenomenon was observed when polystyrene and nylon 6 were blended with styrene–methacrylic acid copolymer as the interpolymer. The existence of such a graft polymer was confirmed by solvent extraction, estimation of the amino group of nylon 6, and identification by differential scanning calorimetry. The physical properties, especially mechanical properties of nylon 6–polypropylene polymer blends, were remarkably improved with increase of maleic anhydride added to the polymer blend. On the other hand, the physical properties those of nylon 6–polystyrene polymer blends were very little improved even in the presence of good dispersibility.
Reaktionsverlauf während der Härtung eines Epoxidharzes mit Dimethylaminopropylamin
Authors: Eyerer Peter
Published: April 2003

Der Vernetzungsverlauf eines Epoxidharz–DMAPA‐Systems wird mittels UR‐Spektroskopie, Kalorimetrie, Zugfestigkeits‐, Mikro‐ und Makrohärte‐, Gleichstromwiderstands‐ und Schubmodulmessungen untersucht. Die Bestimmung des zeitlichen Verlaufes der Glastemperatur während der Vernetzung führte zur physikalischen Aufklärung von Eigenschaftsanomalien bei höheren Vernetzungstemperaturen. Eine Erklärung für den eigenartigen Verlauf der Glastemperatur konnte dagegen nicht gegeben werden.
Préparation, structure et propriétés des membranes obtenues par greffage radiochimique d'acide acrylique sur des films minces de terphane en présence d'agents gonflants
Authors: Marchand J. , Puig J. R.
Published: April 2003

Le greffage de films de 6 microns d'épaisseur en poly(téréphtalate d'éthylène glycol) (PTEG), de marque Terphane, avec l'acide acrylique, conduit à des membranes exploitables en électrodialyse mais inutilisables en osmose inverse. La technique radiochimique permet de réaliser le greffage dans des conditions très satisfaisantes. Les observations portant sur la cinétique du greffage, sur le gonflement des films greffés, sur leur resistance électrique, sur leur cristallinité et enfin sur leur structure révélée par microscopie électronique permettent de mieux comprendre le mécanisme du greffage et mettent en évidence des corrélations étroites entre la structure des films greffés, les conditions du greffage et les propriétés des membranes résultantes. Le rǒle joué par les zones amorphes dans le système considéré revět une importance primordiale: les zones amorphes sont seules susceptibles de recevoir l'acide acrylique et de permettre la formation en leur sein de poly(acide acrylique). Ce dernier s'accumule dans les zones amorphes où sa concentration tend vers une limite déterminée concurremment par deux facteurs. D'une part la barrière physique des zones cristallines s'oppose à l'extension du greffage. D'autre part les conditions měmes de la réaction, dans la mesure où l'état d'enchevětrement ou de réticulation qui peut s'établir entre les chaǐnes de poly(acide acrylique) finit par s'opposer à l'arrivée du monomère, peuvent créer éventuellement une seconde limite au développement de la réaction. Le diphényle utilisé comme agent gonflant paraǐt favoriser l'extension des zones amorphes par l'attaque des zones cristallines. Il est possible que sa présence conduise en outre à un poly(acide acrylique) de poids moléculaire plus faible donc de structure moins enchevětrée et plus ouverte à la diffusion de l'eau, ce qui expliquerait qu'une perméabilité à l'eau ait seulement pu ětre obtenue par greffage en présence de diphényle. L'acide formique utilisé également comme agent gonflant semble avoir eu un résultat opposé en donnant lieu à des taux de gonflement plus faibles. Il est possible que ce composé favorise la formation de poly(acide acrylique) de haut poids moléculaire aboutissant à un pseudo‐gel par enchevětrement moins facilement gonflable. En conclusion, ce travail montre que dans les conditions utilisées, le greffage du PTEG par l'acide acrylique tend vers un taux limite déterminé principalement par le degré de cristallinité. L'armature cristalline du PTEG n'est pratiquement pas altérée. Les propriétés du PTEG sont très diversement affectées par le traitement. La perméabilité à l'eau et la résistance mécanique sont peu modifiées plors que par contre la conductivité électrique est considérablement augmentée.
Effect of stoichiometric concentration of hardener and percentage styrene oxide diluent on the crosslinking and mechanical properties of an epoxy resin cured with DEAPA
Authors: Whiting D. A. , Kline D. E.
Published: April 2003

Epoxy resin was cured with diethylaminopropylamine (DEAPA) in amounts ranging from 10% to 50% of stoichiometric amount. The yield strength of resulting thermosets formed by heat curing at 75°C is found to increase with decreasing amount of hardener. This is attributed to a more densely crosslinked structure resulting from increased tertiary amine‐initiated epoxide–epoxide chain reaction and decreased primary and secondary amine–epoxide reaction. Infrared analysis and swelling data are also presented. Styrene oxide diluent is found to have a moderate effect on mechanical properties in the range from 10 to 25 parts per hundred (phr).
Structure development during melt spinning of linear polyethylene fibers
Authors: Dees J. R. , Spruiell J. E.
Published: April 2003

Apparatus has been developed for studying the development of crystallinity and orientation during the melt spinning of synthetic fibers. Tension in the fiber and temperature, diameter, and x‐ray diffraction patterns are measured as a function of distance from the spinneret for a running monofilament. Measurements are presented for linear polyethylene over a range of spinning variables together with other investigations carried out on the final as‐spun fibers. These data indicate that the development of crystallinity in polyethylene is controlled by a balance between increased crystallization kinetics caused by the stress in the fiber and a tendency for increased supercooling with change in any spinning variable that increases cooling rates in the fiber. The type of crystalline orientation observed, its development during the spinning process, and the changes observed with changes in spinning conditions suggest a model for the as‐spun fiber structure in which varying amounts of row nucleation and twisting of lamellar, folded‐chain crystal overgrowths occur depending on the spinning conditions. As‐spun fiber birefringence was shown to depend primarily on the crystalline orientation. Mechanical properties correlated well with c‐axis crystalline orientation function and spinline stress.
Crosslink density of elastomers. A new gas‐chromatographic method
Authors: Parks C. R. , Brown R. J.
Published: April 2003

The crosslink density of small microtomed samples of rubber vulcanizates has been determined using a gas‐chromatographic method for estimating the amount of solvent in the swollen rubber. The method may be used for determining the variation in crosslink density through thick rubber articles, for determining the change in crosslink density after aging service, or, for the investigation of rubber bonds and interfaces.
Studies of some peculiar effects of temperature on molten high‐density polyethylene properties
Authors: Tanaka Koichi , Takakura Makoto , Koshino Yuji
Published: April 2003

Many HDPE samples show peculiar behavior of melt viscosity at low shear rate and melt strength at constant extrusion rate in a temperature region of about 200° to 250°C. It was found that the degree of the peculiarity of the behavior was affected by temperature, residence time at a temperature, the temperature rise rate, and the kind and quantities of additives. It was concluded that the peculiar effects were due to the crosslinking that a chemical reaction produced. An attempt was made to express the different behaviors of temperature dependence of melt viscosity among many HDPE samples by some simplified equations. It is suggested that both the peculiar changes with temperature of the melt viscosity and those of the melt strength may be produced by the same mechanism. The similarity of the phenomena between HDPE samples exposed to high temperatures and those crosslinked by γ‐rays was found. Finally, a possibility is discussed of predicting the processability of the resin and properties of final products before the processing operation.
Rapid assessment of weathering stability from exposure of polymer films. I. Real and simulated weathering of commercial ABS terpolymers
Authors: Davis A. , Gordon D.
Published: April 2003

Changes in the infared transmission spectra of thin films were used to follow the natural and artificial weathering of ABS terpolymers. Photo‐oxidation of the polybutadiene moiety, which is the major process involved, occurs only after a well‐defined amount of ultraviolet energy has been absorbed. Therafter, unsaturation decreases in a first‐order manner with respect to UV energy absorbed. Under artificial conditions with constant UV intensity, energy absorbed is synonymous with time, but this is not so in natural exposure because of the variability of solar energy and its UV content. The method permits rapid comparison of commercial grades of ABS with the advantage of using natural conditions. It has been shown that pigmentation (3.6 phr brown and 1.25 phr carbon black) increases weathering stability two‐ and fourfold respectively, as assessed by induction energy and rate of disappearance of unsaturation.
Rapid assessment of weathering stability from exposure of polymer films. III. Relative weathering stability of ABS and arylon, a related polymer blend
Authors: Davis A. , Gordon D.
Published: April 2003

Arylon, a blend of an aromatic polysulfone and a terpolymer of acrylonitrile–butadiene and α‐methylstyrene, weathers similarly to ABS. However its first‐order rate constant for the loss of unsaturation is only 0.39 cm2(Wh)−1 as against 0.80cm 2(Wh)−1 for ABS. This slower weathering is probably caused by the decrease in light intensity penetrating Arylon compared with ABS as a result of the high degree of light scattering observed in the former.
Spectroscopic investigation of hydrocellulose phenylosazones in cadoxen solution
Authors: Blair H. S. , Cromie R.
Published: April 2003

Solutions of hydrocellulose phenylosazone in cadoxen are stable when oxygen is excluded. In the presence of oxygen, the absorption spectrum changes, but the change is partially reversible when nitrogen is bubbled through the oxidized solution. It is probable that a hydroperoxide of the hydrocellulose phenylosazone is formed initially and is then decomposed by the basic solvent. The work indicates the importance of using deoxygenated solvents and working in an oxygen‐free atmosphere when preparing cadoxen solutions of hydrocellulose phenylosazone.
Photochemical reactions of high polymers. XIII. Photografting of methyl methacrylate onto the polymers bearing thiosulfate groups
Authors: Tsunooka Masahiro , Ando Nobuya , Tanaka Makoto
Published: April 2003

Polymers bearing pendent thiosulfate groups, that is, sodium poly(vinyl benzyl thiosulfate) (PVBB) and the sodium salt of poly(vinyl hydrothiosulfatoacetate)(PV AcB), were prepared. The photograft polymerization of methyl methacrylate onto these polymers was carried out. The relationships between irradiation time and conversion, degree of grafting, and grafting efficiency were investigated in the photograft polymerization. It was ascertained that the pendent thiosulfate groups acted as effective initiators for the graft polymerization. From the number of endgroups in the homopolymer formed along with the graft polymer, the mechanism of the graft polymerization was discussed and it was verified that the graft polymerization was initiated by the thiyl radical formed by scission of the sulfur–sulfur bond of the pendent thiosulfate group. An unusually high degree of grafting and extremely rapid polymerization rate observed in the graft polymerization suggested the dual functions of thiosulfate‐bearing polymer as initiator and emulsifier. It was found that addition of FeCl2 to this polymerization system increased the rate of polymerization and the degree of grafting but decreased the grafting efficiency. The effect of FeCl2 was interpreted by assumption of a photo‐redox reaction between thiosulfate group and Fe2+.
Photostabilizing effect of Ni(II) chelates in polymers. I. Polystyrene
Authors: Harper D. J. , McKellar J. F.
Published: April 2003

The photostabilizing effect of six Ni(II) chelates in films of polystyrene is compared with their efficiency in quenching triplet benzophenone and a correlation between the two established. In both polymer stabilizing and triplet quenching experiments, the diamagnetic chelates are more effective than the paramagnetic chelates, indicating that the structural arrangement of the ligand around the Ni atom is an important factor in both cases.
Interaction of melt spinning and drawing variables on the crystalline morphology and mechanical properties of high‐density and low‐density polyethylene fiber
Authors: White James L. , Dharod Khushal C. , Clark Edward S.
Published: April 2003

An experimental study of the spinnability and the variation in crystallinity and orientation in high‐density and low‐density polyethylene fibers with melt spinning and drawing conditions has been carried out. Three polymers (two high‐density and one low‐density) and eicosane (C20H42) were studied. The maximum spinnability was in the lower molecular weight high‐density polyethylene. Hermans‐Stein a, b, and c crystallographic axis orientation factors were computed from wide‐angle x‐ray scattering patterns. In the spun fiber, small take‐up velocities cause the b axis to become perpendicular to the fiber axis in each fiber. The c axis increasingly orients itself parallel to the fiber axis as take‐up velocity increases. The a axis orientation is different for each polymer. The results are interpreted in terms of modern theories of crystalline morphology, specifically the development of row structures. In the drawing experiments, the two high‐density polyethylenes necked. A phenomenological theory of necking is discussed. The a, b, and c axis orientation factors were determined for different stages of drawing. In the necked regions and in completely drawn fibers, the c axis was parallel to the fiber axis and the a and b axes are perpendicular to the fiber axis. The tangent Young's modulus and tensile strength of the spun fibers increased with take‐up velocity and in the drawn fibers were an order of magnitude higher than in the spun fiber. The mechanical properties of spun fiber may be correlated with the c axis (Hermans) orientation factor. The drawn fiber shows significant variations in Young's modulus and tensile strength at constant unit cell orientation.
Studies on melt spinning. V. Elongational viscosity and spinnability of two‐phase systems
Authors: Han Chang Dae , Kim Young Woo
Published: April 2003

Isothermal melt spinning experiments were carried out to investigate the elongational flow behavior and spinnability of polymer blends and a calcium carbonate‐filled polypropylene. Blends chosen for study were mixtures of polystyrene (Dow Chemical, Styron 678) with high‐density polyethylene (Union Carbide, DMDJ 4309), and mixtures of polystyrene (Dow Chemical, Styron 686) with high‐density polyethylene (Union Carbide, DMDJ 4309). For the study, measurements were taken of the thread diameter by photographic techniques and of the thread tension by means of a Saxl tensiometer. These measurements were later used to determine the elongational viscosity of the material investigated. It was found that, in all the blends and filled systems investigated, the elongational viscosity decreases with elongation rate and that the relationship between the elongational viscosity and blending ratio is very complex. An attempt is made to offer explanations of the observed complicated relationship with the aid of microphotographs of fiber samples, which display the complexity of fiber morphology in two‐phase systems. It was also found that there exists some correlation between the elongational viscosity and the maximum stretch ratio which may be considered as representing fiber spinnability.
Water permeability of poly(diallyl isophthalate) films
Authors: Rybicky J. , Marton J. P.
Published: April 2003

The prepolymer of diallyl isophthalate is employed as a material for a moistureprotective coating which is applied in the solution form, free of radical initiator. The effect of the absence of radical initiator, temperature and time of cure, and thickness of coat is evaluated in terms of the permeability of water through the protective films of the polyphthalate. Temperature of the noncatalytic cure can be as low as 170°C, and the presence of an initiator in the coating formulation does not bring about any improvement in the moisture resistance of the films.
Effect of resin chemisorption and crosslinking on various fiber properties of cotton
Authors: Patel S. B. , Kulshreshtha A. K. , Mehta P. C.
Published: April 2003

Chemisorption and crosslinking of cotton cellulose has been carried out with DMEU, DMPU, DHEU, and DMDHEU. Various physicochemical properties of resin‐treated samples have been studied and the data subjected to a linear regression analysis. Using the techniques of liquid retention and optical microscopy it has been found that the chemisorbed cotton is characterized by a lower level of bound resin, greater amount of methylol HCHO, and higher swellability of structure in comparison to the crosslinked cotton. This difference of behavior between the two cottons is attributed to greater rigidification and a collapse of porous structure in crosslinked cotton as a result of catalytic activity at the curing temperature. For various resin‐treated samples there exists a linear relationship between the strength and recovery characteristics of single fibers and those of fiber bundles. The losses in fiber strength and extensibility are found to be proportional to the level of bound resin in various samples. Crosslinked fibers show appreciably higher magnitudes of elastic recovery and bundle crease recovery than chemisorbed fibers. The significance of these results is discussed.
Electric field‐assisted grafting of 4‐vinylpyridine on an activated cation exchange membrane
Authors: Belliveau John F. , Bobalek Edward G. , Simard Gerald L.
Published: April 2003

The influence of forced diffusion by a d. c. electric field on the graft polymerization of ionic 4‐vinylpyridine onto a host membrane was determined. The host was a commercial cation exchange membrane. Initiation was by a redox couple of titanious ions at the exchange sites of the membrane and t‐butylhydroperoxide in the bulk solution along with the monomer. Undesirable effects of electrode reactions were avoided by isolation of the electrode compartments with permselective membranes. Measurements were at monomer concentrations of 0.05, 0.1, and 0.2M and d.c. current densities of 0.08 and 0.16 mA/cm2. Applying the field accelerated the graft rate and provided greater control of the amount and distribution of the polymer than when free diffusion alone directed the reaction. This suggests possible value of forced diffusion by an electric field to tailormake membranes to special properties such as in the case of ampholytic mosaic membranes.
Compressive behavior of worked plastics
Authors: Shayota Mofak , Babcock Stephen G.
Published: April 2003

The effect of temperature and loading history on the compressive stress–strain properties of two plastics is described. Polypropylene and nylon cylindrical specimens were reduced in height by 20%, 40%, 60%, and 80%, at room temperature and 25°F below the melt point and at two different deformation rates. Test specimens were cut from these worked billets along two directions, axially and radially. Subsequent compressive stress–strain tests were run using an Instron tester. Results of these tests are presented and compared with the stress–strain curve of the virgin material.
Thermodynamic properties of liquid polyethylene
Authors: Maloney D. P. , Prausnitz J. M.
Published: April 2003

Thermodynamic properties of molten polyethylene are calculated for the temperature range 100° to 300°C and for pressures up to 3000 atmospheres. The calculations are based on limited experimental data augmented by a corresponding‐states correlation and an empirical equation of state. Specific volume, internal energy, enthalpy, entropy, and solubility parameter are presented as functions of temperature and pressure. The results of this study may be useful for engineering design in the high‐pressure polyethylene process.
Dispersions or solutions? A mechanism for certain thickening agents
Authors: Taylor N. W. , Bagley E. B.
Published: April 2003

Hydrolyzed starch–polyacrylonitrile (H‐SPAN) graft copolymers form highly viscoelastic mixtures with water, even at concentrations less than 1% by weight. In many ways these mixtures behave like ordinary polyelectrolyte solutions, but dilution experiments revealed that linear reduced viscosity–concentration plots could not be obtained even under ostensibly isoionic dilution conditions. This result, combined with a determination of gel content from centrifugation studies, led to the conclusion that high viscosity H‐SPAN water mixtures consist of swollen, deformable gel particles closely packed in intimate contact. Under high dilution or at high ionic strength conditions, the gel particles no longer are tightly packed, solvent is present in excess, the viscosity drops precipitously, and the thickening action effectively disappears. For comparative purposes, a commercial thickening agent (Carbopol 941) was examined and found to act in the same way. All reduced viscosity‐concentration curves obtained by dilution, either with salt solutions or water, can be shifted to a single normalized reduced viscosity plot. This shift is done by using as the concentration variable the quantity cQ, where c is the polyelectrolyte concentration and Q is the swelling which the gel particles undergo in an excess of solvent at the corresponding total ionic strength of the solution of concentration c.
Mechanism of low profile behavior in unsaturated polyester systems
Authors: Pattison Victor A. , Hindersinn Raymond R. , Schwartz Willis T.
Published: April 2003

The mechanism by which low profile character is achieved in unsaturated polyester systems has been investigated. Using techniques of microscopy, data are developed that support a model in which micro stress cracking is induced to relieve stress promoted by polymerization shrinkage. Thus the strain is accommodated internally in a molded part, rather than through macroscopic shrinkage of the article.
Modified cellulose acetate prepared from acetic anhydride reacted with cellulose dissolved in a chloral–dimethylformamide mixture
Authors: Clermont L. P. , Manery N.
Published: April 2003

A bleached sulfite pulp (85.0% α‐cellulose) was dissolved in dimethylformamide containing anhydrous chloral and pyridine as catalyst. The clear cellulose solution was then reacted with acetic anhydride under various conditions. The reaction products contained both acetyl groups and chlorine in amounts varying from 20% to 38%. Curves of reaction rates with respect to chlorine and acetyl groups under various conditions of temperature and reactant ratios were similar in appearance, and all the products contained approximately 2 moles of acetyl groups per mole of chloral. Yields varied from 180% after treatment at room temperature (25°C) for 1 hr to 250% after 4 hr. The products could be hydrolyzed in acid with some difficulty but very easily in dilute alkali. The products had low flammability and hygroscopicity. Films cast form acetone solutions had higher permittivity and lower a.c. conductivity than similar films made from cellulose diacetate.
Effect of aerosil on the course of thiuram accelerated sulfur vulcanization
Authors: Ducháček Vratislav , Brajko Vladimír
Published: April 2003

Tetramethylthiuram disulfide (TMTD)‐accelerated sulfur vulcanization of natural rubber has been investigated at temperatures from 100°C to 145°C. Continuous measurements in a Vuremo curemeter were used to estimate the extent of crosslinking, which was plotted against cure time. The cure curves as well as their linearized forms (dependences of the logarithm of the extent of vulcanization on the cure time) clearly show that at lower cure temperatures the course of the vulcanization differs significantly from the first‐order rate law. These digressions have been removed by the addition of a highly dispersed silica gel, Aerosil, which simultaneously speeds up the course of the vulcanization up to the value corresponding to the rate of zinc dimethyldithiocarbamate (ZnDMDC)‐accelerated sulfur vulcanization. These results are in accordance with our recent theory supposing that ZnDMDC is the actual accelerator in TMTD‐accelerated sulfur systems. In the presence of Aerosil, the formation of ZnDMDC from TMTD is catalyzed via dispersed silica gel. Support for this view derives from the temperature dependences of vulcanization reactions. The activation energies of TMTD‐accelerated sulfur vulcanizations in the absence (31 kcal/mole) and in the presence of Aerosil (23.5 kcal/mole) correspond exactly to the values calculated from the rate constants of the thiuram decrease in TMTD‐accelerated vulcanization (30 kcal/mole) and from the rate constants of crosslinking in the dithiocarbamate‐accelerated sulfur vulcanization (23 kcal/mole), respectively.
Viscosity of bead suspensions in polymeric solutions
Authors: Nicodemo L. , Nicolais L.
Published: April 2003

Viscosity measurements made by a cone‐plate viscometer on polyisobutylene in decalin solutions at different concentrations and their corresponding glass bead suspensions with filler loadings up to 40% by volume are reported. The range of shear rate $ \dot \gamma $ investigated is between 0.1 and 1000 sec−1. The solutions show shear‐thinning behavior, and the relative viscosity ηr of the slurries generally decreases with increasing shear rate. The results indicate two different types of mechanism, respectively at high and low shear rates. At low $ \dot \gamma $, the relative viscosity can be correlated extending relations already well known for suspensions in Newtonian liquids which are based on the mechanism of aggregate disruption. The behavior at high $ \dot \gamma $ values is believed to be due to the influence of the filler on the flow properties of macromolecules, in particular on relaxation time. Through a shifting procedure, an increase in relaxation time which depends on filler content and not on polymer concentration is shown.
Ethylene copolymers of N‐substituted acrylamides
Authors: Mortimer George A.
Published: April 2003

Ethylene copolymers containing even small amounts of certain N‐alkylacrylamides show some unusual properties: transparency while semicrystalline, preservation of stiffiness during reduction in crystallinity, and an unusual melt flow‐versus‐solution viscosity relationship. These properties are due to hydrogen bonding between macromolecules. By proper choice of the N‐alkyl group, copolymers containing more than 95% ethylene were made which were stiff, tough, and transparent.
Determination of internal energy contribution to the thermoelasticity of natural rubber during compression by use of a thermomechanical analyzer
Authors: Hwo Chiu‐Hsiung , Bell James P. , Johnson Julian F.
Published: April 2003

A method for measuring the internal energy change of elastomers under compression is demonstrated using a conventional thermomechanical analyzer. The method is rapid and convenient and has a major advantage in that only a very small sample is required. Results are reported for natural rubber cured with two different crosslinking agents. The results are compared with previous work on similar materials in tension and torsion.
An experimental study of the relationship between rheological properties and spinnability in the dry spinning of cellulose acetate–acetone solutions
Authors: Griswold Phillip D. , Cuculo John A.
Published: April 2003

The elastic and viscous properties of five cellulose acetate–acetone solutions, varying from 19.9% to 28.6% solids concentration, are independently determined at 60°C by capillary rheometry techniques. The viscous flow behavior of the solutions is determined over four decades of shear rate. The Bagley analysis is used to determine the entrance pressure drop and the true shear stress at various shear rates. A plot of the entrance pressure drop at the maximum experimental shear rate versus solution concentration undergoes a rapid increase in slope at 24.0% solids concentration, the significance of which is discussed with respect to the development of an elastically deformable chain entanglement network. The die swell behavior of the solutions at 60°C is determined on a commercial‐type dry‐spinning apparatus. When the die swell ratio is plotted versus volumetric flow rate, all five solutions are found to possess a characteristic curve with a distinct maximum. Photographs illustrating the variation of die swell with volumetric flow rate are shown. Die swell measurements are also shown to correlate well with entrance pressure drop measurements. The degree of spinnability of each cellulose acetate–acetone solution at 60°C is found by determining first godet speed at which one or more threads break abruptly. Spinnability is found to go through a maximum at 24.0% solids concentration. The rheological measurements and spinnability results are discussed through the aid of a single rheological parameter incorporating both elastic and viscous solution responses.
Hydrolysis mechanism of crosslinks formed between hydroxymethylated 2‐substituted 4,6‐diamino‐s‐triazines and cotton
Authors: Tashiro Tatsuo
Published: April 2003

Hydrolysis resistance and mechanism of reaction products of hydroxymethylated 2‐substituted (X) 4,6‐diamino‐s‐triazines (MXT) with cotton fabrics has been studied. Finishing reagents used were MXT having the following substituents: X = CH3O (MMT), (CH3)2CHO (MIPT), CH3 (MAG), C2H5NH (MEM), HOC2H4NH (MHEM), and (HOC2H4)2N (MBHEM). For comparison, trimethylolmelamine (TMM), dimethylolurea (DMU), dimethylolethyleneurea (DMEU), and dimethylol‐ethyltriazone (DMET) were used. Hydrolysis was carried out in buffer and NaOH solutions of various pH's for 30 min at 80°C. The order of hydrolysis resistance of crosslinked reagents was determined from the nitrogen contents retained. It was as follows: pH 1, MROT < MRNT < MRT; pH ≧ 2, MROT > MRT > MRNT; pH ≦ 13, MROT > MRNT; pH 14, MROT < MRT < MRNT, where MROT is hydroxymethylated 2‐alkoxy (MMT, MIPT), MRT is hydroxymethylated 2‐alkyl (MAG), and MRNT is hydroxymethylated 2‐alkylamino‐4,6‐diamino‐s‐triazine (MEM, MHEM, MBHEM). This fact can be explained in terms of the basicity constant (pKb) of crosslinked MXT with cotton (approximately pKb) of 2‐substituted 4,6‐diamino‐s‐triazine (XT). The hydrolysis rates of crosslinked MMT, MAG, and MEM were determined at pH 2. The activation energies were 21.8 for MMT, 20.9 for MAG, and 21.0 kcal/mole for MEM.
Powder densities—specific surface relations for PVC resins
Authors: Ravey M. , Waterman J. A.
Published: April 2003

The bulk and tap densities of a series of PVC resins were found to be related linearly to each other and hyperbolically to the resin specific surface.
Fissure sealants
Authors: Keizer S. , Arends J.
Published: April 2003

The adhesive bonding of a fast‐setting system consisting of three different monomers to etched human enamel surfaces was investigated. Combinations of MMA, methacrylic acid, and adducts of glycidyl methacrylate andp‐substituted phenols have been employed. Best results were obtained with hydrogen ort‐butyl‐substituted phenols. It is shown that a well‐chosen three‐component system has the advantage of a very low initial viscosity and fast setup times over two‐component systems. Various compositions of three‐component systems were studied. The maximum bond strength between enamel surfaces and the polymer was 80 kg/cm2. Setup times as well as in vivo setup times are reported.
Compositional analysis of the styrene–isobutylene copolymer
Authors: Forrette John E. , Rozek Adele L.
Published: April 2003

Analysis for composition of the styrene–isobutylene copolymer has been accomplished by independent techniques which include carbon‐hydrogen analysis and infrared and NMR spectroscopy. The use of blends of homopolymers presents difficulties in establishing true absorptivities for the solution of two‐component systems, and appropriate corrections were applied to enable use of IR as an analytical technique. Carbonhydrogen elemental analysis and NMR spectroscopy were used to verify the IR results.
Rheological phenomena in polymerization reactors: Rheological properties and flow patterns around agitators in polystyrene–styrene solutions
Authors: Ide Yoshiaki , White James L.
Published: April 2003

The rheological properties (viscosity and principal normal stress difference) of poly‐styrene–styrene solutions at concentrations of 15, 20, 30, 35, 43, 50 and 57 wt‐% have been measured at 60°C. The flow patterns around a sphere, disc, turbine, and screw propellers in such solutions have also been determined. The second‐order fluid theory of viscoelastic fluids containing parameters determined from our rheological measurements has been used to predict the flow patterns about the sphere. The observed flow patterns are in good agreement with the theoretical predictions based upon externally measured rheological properties. The implications of this study of this behavior of batch and CSTR polymerization reactors are discussed.
Plasticity in peeling
Authors: Duke A. J.
Published: April 2003

Contrary to classical theory, a high proportion of bond failures by peeling involve progressive plastic adherend flexural yield. Such yield occurs with adherend thicknesses below a critical value, Tc, which is shown calculable by combining elastic peel mechanics with plastic bending criteria. The geometry of such “peel with yield,” and thence the moment‐controlled peel forces, can be accounted for only if the adhesive is also recognized as behaving essentially plastically. Subsequent plastic adherend unbending is important with highly extensible adhesives. The geometry of “legging” peel in such cases is best described by fully plastic mechanics. These are derived and shown to account for literature data on dependencies of peel force upon peel rate and adhesive thickness. “Stick‐slip” peel phenomena are indicated to be controlled by recurring interacting plastic–elastic transitions, in both adhesive and adherend: adhesive strain rate is critical in such phenomena. Four regimes of peel behavior can therefore apply as adherend thickness (T) increases, with peel forces proportional respectively to T0, T2/3, T3/2 (above Tc) and finally controlled by moment limitations due to joint configurational constraints (“cleavage”).
A study of interfacial polycondensation in a continuous reaction system
Authors: Griskey Richard G. , Hundia S. R. , Siskovic Nandor
Published: April 2003

A study was made of the interfacial polycondensation of nylon 6–10 in a continuous reaction system since no previous detailed work of this type was reported in the literature. An experimental stirred‐flow reactor was used to determine both yield and intrinsic viscosity (molecular weight) as functions of reactant ratio (sebacoyl chloride/hexamethylenediamine) and Reynolds number. It was found that mass transfer was the controlling factor in the reaction system. The yield as a function of Reynolds number correlated directly with the behavior of mass transfer coefficient. In addition, reactant ratio effects on yield were shown to relate to change in organic phase volume. Intrinsic viscosity was a maximum in the same reactant ratio range as for batch and continuous cascade systems studied earlier. Intrinsic viscosity behavior was also shown to relate to mass transfer. The jD data for the reactor systems were also determined. These values were shown to correlate if normalized for reactant ratio.
The depolymerization of low molecular weight poly(chloroacetaldehydes)
Authors: McCain G. H. , Sanders J. M.
Published: April 2003

Stability of low molecular weight (D.P. < 300) polychloral has been found to be a function of the amine used as the polymerization initiator. The polymer produced with diethylamine unzips much more rapidly than that made with triethylamine. This investigation also showed that ester endcaps provide little protection from amine‐induced depolymerization. The amine‐initiated copolymer of chloral and dichloroacetaldehyde behaves anomalously in that it is unstable in the presence of normally inert organic solvents. Mechanisms are proposed to account for these observations.
Formation of 2,4‐dinitrophenylhydrazones in polyethylene film treated with chromic acid mixture
Authors: Kato Koichiro
Published: April 2003

2,4‐Dinitrophenylhydrazones formed by the reaction of 2,4‐dinitrophenylhydrazine with carbonyl groups were formed in polyethylene film oxidized with chromic acid mixture. The changes in amount of the hydrazones formed in the films were inferred by comparing the absorptions in the ultraviolet spectra and compared with changes in wettability with water of the films. In the early stage of treatment with chromic acid mixture, the hydrazone amount increased and the contact angle of water decreased. After the early stage of the treatment, the hydrazone amount decreased slightly and increased again thereafter, and the contact angle of water seemed to increased slightly and decreased again thereafter. The hydrazone amount increased with increase in time of the reaction between 2,4‐dinitrophenylhydrazine and oxidized polyethylene film. For temperatures of treatment with chromic acid mixture above about 45°C, the hydrazone amount increased with rise in the treatment temperature and rate of the increase increased with rise in the treatment temperature, and the contact angle of water decreased with rise in the treatment temperature, and the rate of the decrease seemed to increased with rise in the treatment temperature.