bluuebunny/crossref_metadata_2025 huggingface dataset:
The synthesis and evaluation of cyclic olefin sulfone copolymers and terpolymers as electron beam resists
Authors: Gipstein Edward , Moreau Wayne , Chiu George , Need Omar U.
Published: April 2003

Poly(cyclopentene sulfone) (PCPS) and poly(bicycloheptene sulfone) (PBCHS) copolymers have been evaluated as potential positive electron beam resists which have good thermal properties and which show high sensitivity to ionizing radiation. It was found that thin copolymer films could be processed as resists but that films greater than 3000 Å thick cracked in the solvents used to dissolve the radiation‐exposed regions. Incorporation of plasticizing additives did not improve the film properties. Films from low molecular weight polymer fractions cracked less in solvents, but higher radiation doses were required to offset the reduced sensitivity. This resulted in the formation of intractable residues in the exposed regions which appear to be crosslinked polymer. Bicycloheptene monomers with specific functional groups did not improve the properties of the copolymer films. Terpolymerization with α‐olefins such as butene‐1 and cis‐2‐butene plasticized these films and reduced their tendency to crack in solvents. Poly(cyclopentene sulfone–co–butene‐1 sulfone) films were found to have the best properties, and 1.25‐μ resist images could be etched in SiO2 layers at an exposure dose of 4 × 10−6 C/cm2 at 25KV. However, one important limitation of this terpolymer was the low dissolution rate ratio between the exposed and unexposed regions. Since straight‐walled relief images are essential to the formation of high‐resolution patterns, the usefulness of this terpolymer as an electron beam resist appears to be hindered by the limited choice of good solvents to maximize the dissolution rate ratio. PBCHS block terpolymers containing methyl methacrylate (MMA) or methacrylic acid (MAA) were synthesized to improve the solubility in solvents and to incorporate the properties of methacrylates. PBCHS–MMA films cracked in solvents after irradiation; PBCHS–MAA polymers were too insoluble to form resist films.
Amylose graft polymers made by 60Co gamma‐irradiation
Authors: Hofreiter B. T.
Published: April 2003

Model products were needed to elucidate structure–property relationships in a starch graft polymer research program. Simultaneous irradiation of amylose and acrylamide in oxygen‐free, dilute aqueous solutions gave graft polymers with maximum add‐on of about 16%. The graft polymers were separated from homopolymer and subfractionated by incremental additions of nonsolvent (methyl or ethyl alcohol) to irradiated aqueous reaction media. The graft polymers were fairly homogeneous in graft content. Effects were determined of ratios of monomer to substrate, dose rate, and total dose on yield, graft content, intrinsic viscosity, and homopolymer characteristics. Under some conditions, crosslinks probably formed between graft side chains. Large differences in solution properties of a synthetic mixture of separately irradiated amylose and acrylamide and an irradiated solution of amylose and acrylamide indicated that grafting had occurred. Further evidence for true grafting was based on the action of a selective precipitant, n‐butyl alcohol, on graft polymer solutions.
A new method for torsional pendulum analysis of polymers through the glass transition region
Authors: Fava R. A. , Chaney C. E.
Published: April 2003

A freely oscillating torsional pendulum has been used to measure the dynamic‐mechanical loss of polymers through the softening temperature by encapsulating the polymer in a rigid matrix of cured phenolic resin. The method is illustrated with loss curves through the glass transition region of poly(vinyl chloride), polystyrene, a styrene–maleic anhydride copolymer, poly(phenylene oxide), and two binary alloys involving these polymers. The advantages and simplicity of the technique are emphasized.
Fatigue crack retardation in polycarbonate
Authors: Banasiak D. H. , Grandt A. F. , Montulli L. T.
Published: April 2003

Results are presented from a recent study of the influence of tensile overloads on fatigue crack growth in polycarbonate. Fatigue cracks were grown under conditions of constant range in stress intensity factor in four‐point bend specimens. The data presented here indicate that tensile overloads may significantly retard subsequent fatigue crack growth in polycarbonate. The period of delay in crack growth was shown to increase with the magnitude of the overload. Recovery of stable crack extension following the overload appeared to involve reinitiation of separate crack growth sites at the tip of the blunted crack tip, similar to the original crack initiation at sharp V‐notches.
Vena contracta suppression in dilute polymer solutions
Authors: Chiou C. S. , Gordon R. J.
Published: April 2003

Very small amounts of high molecular weight polymers were found to eliminate vena contracta formation in flow through a circular orifice. This effect was reflected in the decreased efflux time for drainage between two fixed levels in a tank, reductions up to 30% being obtained. Aqueous solutions of seven commercially available polymers were studied, consisting of a poly(acrylic acid), two polyacrylamides of different degrees of hydrolysis, and four poly(ethylene oxides) of widely differing molecular weights. The poly(acrylic acid) and two highest molecular weight poly(ethylene oxides) each caused a sudden drop in efflux time at a “critical concentration”, which was 2, 50, and 90 wppm, respectively, for these three polymers. An explanation of this phenomenon in terms of the high Deborah number flow field existing near the orifice edge is advanced. In the case of the polyacrylamide solutions, a very gradual reduction in efflux time with increasing polymer concentration was observed, beginning at about 3 wppm. Coincident with this was the formation of a wine‐glass stem or converging flow field upstream of the orifice. Such a flow field was not observed for the other solutions. It is suggested that vena contracta inhibition with polyacrylamide is simply a manifestation of solution die swell. The reason for the differing efflux time behavior between the various polymers is not known and represents a challenging problem for further study.
Annealing of plasticized PVC. Dilatometric and DSC observations
Authors: Garrett T. B. , Goldfarb L.
Published: April 2003

Isothermal dilatometric measurements on quenched, plasticized PVC have been made at a series of temperatures, and a mathematical expression has been obtained to described the specific volume as a function of time. The results of these measurements, along with those obtained using differential scanning colorimetry (DSC) for the change in enthalpy accompanying annealing, clearly show a change in the character of the annealing process with rising temperature; but the underlying molecular kinetic mechanism apparently remains unchanged.
Segregated and two‐environment reactor models—calculation of molecular weight distributions
Authors: Ahmad Abu , Anthony Rayford G.
Published: April 2003

An efficient procedure is presented for calculating molecular weight distributions for segregated reactors and two‐environment reactor models.
Load and temperature dependence of frictional force and frictional electrification in friction between polymer films obtained by simultaneous measurements
Authors: Ohara Keiji
Published: April 2003

Simultaneous measurements of frictional force (F) and frictional electrification charge density (σ) were carried out for PS/Ny, PC/PET, and PS/PC polymer film sample systems in the temperature range of 10° to 100°C under various loads (W). Load dependence of F and σ were expressed by F = αWn and σ = βWm. Values of n and m changed with the number of rubbings and temperature. Rate of decrease in n became larger at about 90°C for all sample system. For PS/Ny systems, the values of m and n changed in a similar manner. This behavior was explained in terms of variations in true contact area. Values of F and σ were at maxima and/or began to increase at the temperatures corresponding to the glass transition temperature of the α‐peak temperature in viscoelastic polymers. The maxima of F and σ may appear when the frequency of thermal motion of molecules taking part in the adhesion and separation process coincides with the frequency of mechanical motion of adhesion and separation (friction) between two surfaces, namely, when the true contact area becomes maximum.
Distribution of carbon black in SBR
Authors: Oono Ryo
Published: April 2003

The distribution of HAF carbon black in SBR was studied with the electron microscope and Fraunhofer diffraction. The interparticle distance between black aggregates is 8000 Å at 20 phr and 7000 Å at 40 phr, but above 60 phr it spreads broadly in the vicinity of 4000 Å. The size of black aggregates at 20 phr extends from 300 Å to 3000 Å, and the average diameter is 1200 Å. At 40 phr and 60 phr, black trends to aggregate more than at 20 phr and the average diameter is about 1500–1600 Å; the maximum diameter exceeds 5000 Å. In a black aggregate, there are about 40 spherical particles independently of filler concentration. From the relation between the size and interparticle distance, the connection of black aggregates initiates at 40 phr level and affects the physical properties of filled rubber.
Vulcanization of butyl rubber by p‐quinone dioxime
Authors: Gan L. M. , Soh G. B. , Ong K. L.
Published: April 2003

The vulcanization of butyl rubber by p‐quinone dioxime oxidized by red lead and tetrachloroquinone was investigated. The maximum physical effective crosslinking density of the vulcanizates appeared to be when p‐quinone dioxime and the oxidizing agent were equimolar. The formation of one physical effective crosslink required one molecule of p‐quinone dioxime. Chemical reactions are suggested for the vulcanization steps.
Properties of elastomers crosslinked by bisglycidyl ether of 2,2‐bis(p‐hydroxyphenyl)‐1,1,1‐trichloroethane
Authors: Brzozowski Zbigniew K. , Gajewski Mieczysław , Brzeziński Zdzisław
Published: April 2003

Chlorobisphenolic epoxy resins in crystalline form, e.g., bisglycidyl ether of 2,2‐bis(p‐hydroxyphenyl)‐1,1,1‐trichloroethane (BGECBP) and the system sulfur–N‐cyclohexyl‐2‐benzothiazolesulfonamide were used as crosslinking agents for vulcanization of butadiene–styrene and butadiene–acrylonitrile rubber. The density of crosslinking was determined by the equilibrium swelling method and on the basis of the Mooney‐Rivlin equation which gives the relation between stress and elongation. The dynamic properties, namely, G′ and G″ and mechanical loss factor δ, were determined. On the basis of these results, mechanisms for the crosslinking reaction were advanced, the activation energy was determined, and comparisons between crosslinking rates by different systems were made. It was found that vulcanizates crosslinked by BGECBP possess higher heat aging resistance and lower glass transition temperatures in comparison with those crosslinked by means of sulfur in the presence of N‐cyclohexyl‐2‐benzothiazolesulfonamide.
Bromostyrene‐crosslinked polyesters. III. Electrical properties
Authors: Konieczny N. , Marom G. , Weinberg A.
Published: April 2003

Volume resistivity, dielectric strength, dielectric constant, and loss tangent of unsaturated polyester resins and their GRP were studied as a function of the bromine content of the resin. The bromine was introduced by using bromostyrene as the crosslinking monomer. Bromine content was established by partial or total replacement of the styrene. Also, the effects of short and long water‐boil treatments on these properties were investigated. The electrical and dielectrical properties were shown to be independent of the bromine content of the resin.
Application of rayleigh spectroscopy to the study of emulsion and dispersion polymerization and polymers
Authors: Killgoar Paul C. , Dickie Ray A.
Published: April 2003

Application of Rayleigh spectroscopy for characterization of particle size in nonaqueous dispersion and water‐based emulsion paint resins is described. The technique allows a straightforward and rapid estimation of particle size; the measurement does not require exact determination of scatterer concentration. For monodisperse samples, unambiguous results are obtained for particles at least up to 50 μm in diameter; for polydisperse samples, an average size heavily weighted by large particles is obtained. Typical experimental results on monodisperse and polydisperse water‐based latexes and on polydisperse nonaqueous dispersion resins are described. In the latter case, comparison of electron micrograph and light scattering size determinations indicates that the light scattering experiment yields approximately a z‐average radius. Observations on particle formation and growth during polymerization are also described.
Some limitations on the detection of high elongational stress effects in dilute polymer solutions
Authors: Ting R. Y. , Hunston D. L.
Published: April 2003

The elongational flow behavior of dilute polymer solutions is of great current interest because it has been suggested that elongational viscosity effects may be involved in a number of phenomena such as turbulent drag reduction and flow cavitation suppression. Unfortunately, recent experiments, in trying to investigate elongational effects, have produced widely varying results. In this paper, an attempt is made to analyze one of the factors that contribute to this diversity. By using a generalized convected Maxwell model, it is shown that in a transient elongational flow, both stretching rate and flow time must reach the proper values before high stress levels can be observed. This is true for both accelerating flows such as through a cone or wedge and decelerating flows such as in a free jet. Since most previous experiments have not considered flow time, consistent results cannot be expected. Consequently, the proper control of all flow conditions is an essential requirement when trying to observe high stress levels. The results presented here provide valuable guidelines in this regard.
Ultrasonic studies of polycarbonate, polysulfone, and polyether sulfone
Authors: Phillips D. W. , North A. M. , Pethrick R. A.
Published: April 2003

Ultrasonic attenuation and velocity measurements are reported for samples of polycarbonate, polyether sulfone, and polysulfone over a temperature range from 10° to 80°C and over a frequency range from 5 to 35 MHz. Observed relaxations are ascribed to short‐range motions of the polymer backbone—here designated the α process. The amplitude of the absorption initially decreased with increasing draw ratio, but after two years returned to the values characteristic of undrawn samples. The longitudinal wave velocity increased with draw ratio in a manner consistent with the creation of molecular order and remained constant over two years. Differences in the attenuation properties between the three polymers studies are discussed in terms of the chemical structure and the macroscopic morphology of the samples.
A new method for correcting axial dispersion in GPC
Authors: Marais L. , Gallot Z. , Benoît H.
Published: April 2003

In this paper, a new method for correcting GPC results in order to take into account the axial dispersion of a given set of columns is proposed. The idea is to evaluate the different average molecular weights and the polydispersity for a given elution volume. In order to do so, one needs only to know the efficiency of the set of columns and the different derivatives at a given point of the chromatogram. Some possible applications of this method are reviewed mainly for the characterization of polydispersity and for the determination of the viscosity law if one uses the universal calibration.
A new process of decrystallization and partial acetylation of cellulosic materials
Authors: Kulshreshtha A. K. , Dweltz N. E.
Published: April 2003

A new process of decrystallization of cellulosic materials8 is described. The process involves the preparation of alkali‐cellulose and an interaction between alkali‐cellulose and acetic anhydride. The decrystallized products thus obtained are partially acetylated and are designated as SPA (S for swollen, PA for partially acetylated) products. The effect of varying the alkali concentration on the structure and mechanical properties of SPA products is described. Maximum decrystallization is obtained when the swelling is carried out in alkali of intracrystalline swelling strength, prior to treatment with acetic anhydride. Acetylation is instrumental in retaining the highly decrystallized state. The structure of SPA cotton was characterized using chemical analyses, infrared spectroscopy, and x‐ray diffraction.
Basic principles of thermal degradation and thermal stabilization of poly(vinyl chloride). Mathematical model of the action of PVC thermal stabilizers
Authors: Prochaska Krzysztof , Wypych Jerzy
Published: April 2003

A model of the action of chemically homogeneous thermal stabilizers of poly(vinyl chloride) is shown. Based on the described computer program and experimental data, the proposed model is confirmed and rate constants of the reaction of stabilizers with HCI and the effect of the products of this reaction on the kinetics of PVC degradation are calculated.
Quinoxaline/phenylquinoxaline copolymers
Authors: Hergenrother P. M.
Published: April 2003

The thermal crosslinkability of the quinoxaline moiety incorporated within poly(phenylquinoxalines) was demonstrated by differential scanning calorimetry (DSC), torsional braid analysis (TBA), and high‐temperature adhesive evaluation. Several homopolymers, random copolymers, and polymer blends were prepared and evaluated. A new bis(1,2‐dicarbonyl) monomer, 4‐(4‐phenylglyoxalylphenoxy)phenylglyoxal hydrate, was prepared and reacted with 3,3′, 4,4′‐tetraaminobiphenyl to provide a polymer where a phenyl group was located on alternating quinoxaline rings. The apparent Tg of this polymer was initially 280°C and increased to 360°C after exposure to 400°C for 0.5 hr in air.
Isotactic polystyrene characterization by gel permeation chromatography in tetrahydrofuran
Authors: Guenet J. M. , Gallot Z. , Picot C. , Benoit H.
Published: April 2003

Isotactic polystyrene fractions were characterized by gel permeation chromatography (GPC) in tetrahydrofuran (THF) at 25°C. From the universal calibration method, a viscosity law has been established allowing determination of the correspondence between the molecular weight GPC calibration laws for APS and IPS. The validity of characterization of IPS by this method was confirmed with light scattering and osmometry.
Electron spin resonance studies on photodegradable polymers
Authors: Windle John J. , Freedman Bernard
Published: April 2003

Films of polyethylene (PE), polypropylene (PP), and polystyrene (PS) containing 1% of selected halogen compounds and films without additives were UV irradiated (253.7 nm) at 77°K and their electron spin resonance (ESR) spectra compared. In each case, the spectra were characteristic of the polymer, and the presence of the additive mainly enhanced the radical yield. No signal was observed for the additives alone after irradiation, suggesting that when incorporated into the polymer, they serve as photosensitizers rather than as primary sources of free radicals in promoting photo‐chemical degradation.
Photo‐oxidation and photoprotection of the surface resin of a glass fiber–epoxy composite
Authors: George G. A. , Sacher R. E. , Sprouse J. F.
Published: April 2003

The rapid photo‐oxidation of the surface epoxy resin of a commercial seven‐ply laminate (Scotchply 1009‐26) is due principally to the epoxy novolac resin component. The photo‐oxidation rate of this resin is eight times that of the other component, a bisphenol A epoxy resin. This rate depends on the conditions of cure, and photo‐initiation occurs in part through aromatic carbonyl groups formed by oxidation of the methylene linkages of the novolac at the cure temperature (160–180°C). Inhibition of this thermal oxidation by vacuum cure or a chain‐terminating antioxidant increases the photostability. Photoprotection of thin resin sections by the UV stabilizer 2‐hydroxy‐4‐isooctoxybenzophenone and an epoxidized analog is assessed.
Environmental stress cracking of polyethylene
Authors: Singleton C. J. , Roche E. , Geil P. H.
Published: April 2003

Deformation of polyethylene in environmental stress cracking (ESC) agents results in changes in both the mechanism of deformation and structure of the resulting drawn material. Stress‐cracked failure surfaces are highly fibrillar, the fibrils having less elastic recovery than those in samples drawn in air. In thin films drawn in ESC agents, small blocks of the lamellae remain undrawn and attached to the fibrils drawn across micronecks. The ESC agents are suggested to weaken the cohesion between the fibrils in samples drawn beyond yield as well as the cohesion between mosaic blocks or similar structural elements in the original lamellae as they are being reoriented to form the fibrils. The stress is thus supported by a number of independent, nonuniform fibrils rather than a coherent structure; the weakest of these fibrils fail in turn as the crack propagates through the sample.
The effluent analysis of several pyrrone and polyimide precursors during cyclization
Authors: Sykes George F. , Young Philip R.
Published: April 2003

A study was conducted to determine the degree of cyclization occuring in a series of four pyrrone and two polyimide prepolymers. These materials were heated from 25° to 400°C at 2°C/min in a helium atmosphere, and the effluent was sampled at regular intervals by a gas chromatograph/mass spectrometer technique. Quantitative analysis of this effluent indicated that the pyrrone polymers were less than 80% converted under these conditions while the polyimides were essentially fully converted. Significant amounts of carbon dioxide were found to be eliminated as the pyrrone polymers cured. This evolution was attributed to the loss of carbon dioxide from intermediate stages during cure and, in some cases, to the decarboxylation of unreacted groups. Support data obtained on model compounds are also presented.
On the form of the strain energy function for a family of SBR materials
Authors: Arenz R. J.
Published: April 2003

A strain energy function of the Valanis‐Landel type, W = w(λ1) + w(λ2) + w(λ3), is shown to be applicable to styrene–butadiene rubber (SBR) materials having varying crosslink densities νe. A previously obtained functional form of the strain energy derivative w′(λ), normalized by dividing by νe, is confirmed by one of the validity check plots in which a single curve represents the whole body of large‐deformation test results for all degrees of biaxiality and crosslink density.
Localized radiation grafting of flame retardants to poly(ethylene terephthalate). I. Bromine‐containing monomers
Authors: Liepins R. , Surles J. R. , Morosoff N. , Stannett V. T.
Published: April 2003

Vinyl bromide was used as a model for bromine‐containing flame retardants in developing methodology for localizing flame retardants either on the surface of the filament, uniformly throughout it, or predominantly at the core. SEM–x‐ray microprobe techniques were used in the verification of the location of the flame retardant in the filament. The flame retardance efficiency of PVBr was then correlated with its location in the filament. Grafting other bromine‐containing flame retardants showed a wide range of efficiencies which depended not only upon the location of the grafting within the filament but also upon the structure of the compound. For the various bromine homopolymer grafts, the apparent thermal stability of the graft and its flame retardance efficiency may be simply related to the alpha aliphatic hydrogen‐to‐bromine ratio. The lower this ratio is, the higher the efficiency. VBr copolymers and terpolymers showed wider variation in flame retardance efficiencies. This is attributed to large variations in melt viscosity of the different grafted materials. The grafts showed only small changes in their melting points and minimal changes in tenacity and stiffness. However, grafting induced large increases in the elongation.
Entanglement networks of 1,2‐polybutadiene crosslinked in states of strain. IV. States of ease and stress–strain behavior
Authors: Carpenter Rick L. , Kramer Ole , Ferry John D.
Published: April 2003

Linear 1,2‐polybutadiene, glass transition temperature (Tg) −18°C, is crosslinked at −10°C, to −20°C by γ irradiation while strained in simple extension, with extension, ratios (λ0) from 1.2 to 2.7. After release, the sample retracts to a state of ease (λs) at room temperature. From equilibrium stress–strain measurements up to a stretch ratio relative to the state of ease (Λ) of 1.2, together with λ0 and λs, the concentration of network strands terminated by trapped entanglements (νN) is calculated. For this purpose, a three‐constant Mooney–Rivlin formulation is used, in which the entanglement network is described by Mooney–Rivlin coefficients C1N and C2N, whereas the crosslink networks is described by the coefficient C1x only. The ratio ψN = C2N/(C1N + C2N) is estimated from parallel studies of nonlinear stress relaxation of the uncrosslinked polymer, taking into account the thermal history before and during irradiation. For substantial degrees of crosslinking, i.e., for R0′ = νx/νN > 0.4 (where νN is the concentration of network strands terminated by crosslinks), and for λ0 < 1.8, C2N agrees rather well with the value obtained from stress relaxation of the uncrosslinked polymer in the range of time scale where it is nearly independent of time (1.87 X 105 pascals). The corresponding value of νN is 2.3 × 10−4 moles/cm3, in good agreement with that obtained from viscoelastic measurements of the uncrosslinked polymer in the plateau zone (2.5 × 10−4). However, for R0′ ≅ 0.2, smaller values of C2N and νN are obtained, indicating that for low degrees of crosslinking the entanglements are not completely trapped. Also, for higher values of λ0, C2N and νN turn out to be somewhat smaller. Similar, less extensive results were obtained previously on a 1,2‐polybutadiene with somewhat higher vinyl content and a higher Tg. Crosslinked samples of both these polymers were subjected to equilibrium stress–strain measurements in simple elongation from the state of ease at higher strains up to Λ = 1.7. The results agreed closely with calculations from the three‐constant Mooney–Rivlin theory.
Kinetics of alkali‐catalyzed m‐cresol‐formaldehyde reaction
Authors: Malhotra H. C. , Gupta V. K.
Published: April 2003

The alkali‐catalyzed reaction of m‐cresol with formaldehyde carried out at 65°, 70°, 75° and 80°C and at pH 7, 8, 9, 9.4, and 10 follows second‐order kinetics. The rate is found to increase with increase of pH. The overall rate constant (k) has been resolved into stepwise rate constants (k1, k2, and k3) for the formation of monomethylol, dimethylol, and trimethylol cresol, respectively. For this purpose, the rate equations for the various possible steps have been given and the concentrations of the various methylol cresols formed determined. The experimental and calculated values of k at pH 10 and temperatures of 65°, 70°, and 80°C have been found to agree well within the experimental errors. Entropy of activation and the Arrhenius parameters for the overall reaction have also been calculated.
Casting of organic glass by radiation‐induced polymerization of glass‐forming monomers at low temperature. II. Optical strain of remaining stress type
Authors: Okubo Hiroshi , Yoshii Fumio , Kaetsu Isao , Honda Shigeharu
Published: April 2003

Previously it was found that casting could be carried out efficiently without strain formation by radiation‐induced polymerization of glass‐forming monomers. Two types of strain were observed in casting: thermal stream type, which was studied previously, and remained stress type. In this report, the effect of various factors on the formation of remaining stress‐type strain in radiation‐induced casting polymerization was studied. It was found that the molecular weight of prepolymer did not affect strain formation, while prepolymer concentration and viscosity of the system had a serious influence on strain formation. It could be deduced that this type of strain formed as a result of remaining inner stress due to poor relaxation of the shrinking stress. It was realized that less volume shrinkage of glass‐forming monomers accompanying casting polymerization reduced the strain formation of this type in radiation‐induced casting polymerization at low temperatures.
Poly(1,3,4‐oxadiazoles). Effect of structure on polymer properties
Authors: Varma I. K. , Geetha C. K.
Published: April 2003

Poly(1,3,4‐oxadiazole‐2,5‐diylvinylene) and poly(1,4‐phenylene‐1,3,4‐oxadiazole‐2,5‐diylvinylene) were prepared by polymerizing different quantities of terephthalic acid (T), maleic acid (M), and hydrazine sulfate (HS) in the presence of fuming sulfuric acid. Homopolymers of M and T and various copolymers of M:T were prepared. The polymers were characterized by viscosity, IR, UV, and elemental analysis. Their solubility in different solvents was investigated. The relative thermal stability of the polymers was evaluated by TGA and DTA.
New coating materials prepared by radiation‐induced polymerization. I. Mar‐resistant coating composition and properties
Authors: Okubo H. , Kato M. , Yoshida M. , Ito A. , Kaetsu I.
Published: April 2003

A mar‐resistant coating system was obtained by screening combinations of silicone and vinyl compounds. It was found that binary systems, such as the γ‐glycidoxypropyltrimethoxysilane–glycidyl methacrylate system, were excellent not only in mar resistance but also in adhesion to base resin polymers. Haze values of these coatings, after the sand‐falling test, reached less than 10%. The coating process consisted of three steps: the preparation of prepolymer, the coating to plastic surface, and the curing of the coating by heating. It was found that the prepolymerization step could be performed by irradiation very conveniently; the control of viscosity for coating application and thickness control could be possible without any gel formation. These coatings were also good in weather resistance due perhaps to the good adhesion to base resin and could be applicable to plastic spectacles, glazing materials, and a variety of other products.
The filler–elastomer chemical link and the reinforcement of rubber
Authors: Le Bras Jean , Papirer Eugene
Published: April 2003

Reinforcement, the improvement of the service life of rubber goods, is dependent on the behavior of the carbon black–elastomer interface. It is generally believed that the interaction between the filler and the matrix involves physical and chemical forces. The aim of this work is to demonstrate the significance of the chemical interaction. In order to demonstrate the influence of the chemical bond without interference of physical forces, the problem is approached in a different way. The chemical bond is first realized by grafting the polymer onto the carbon surface. Then, two mixes are prepared by avoiding milling: one with the grafted black and the other with regular black. The comparison of the static and dynamic mechanical properties highlights the influence of the chemical bonding of the elastomer onto the black: the grafted black bestows much higher performance to the corresponding vulcanizate than does the regular black. However, the degree of reinforcement observed is somewhat lower than the one obtained by dry milling.
The identity of the amyl branch in low‐density polyethylenes
Authors: Randall James C.
Published: April 2003

Amyl branches have been positively identified as one of the principal short short chain branches in low density polyethylenes prepared by high pressure processes.
The pyrolysis of cellulose derivatives
Authors: Brown W. P. , Tipper C. F. H.
Published: April 2003

The thermal degradation in vacuo of ethyl cellulose and cellulose acetate in the form of very thin films or bulk material between 230° and 320°C has been studied. With the ethyl cellulose films, volatilization (as measured by weight loss) was a first‐order process up to about 50% reaction, with an activation energy of 208 kJ/mole. This is about the same as that associated with the initial drop in intrinsic viscosity of the solid during bulk pyrolysis, in which very high molecular weight material, probably crosslinked, was formed at a later stage. The volatile products from ethyl cellulose included H2O, CO, CO2, C2H4, C2H6, C2H5OH, CH3CHO, unsaturated aliphatic compounds, and furan derivatives. Acetic acid and acetyl derivatives of D‐glucose were produced from cellulose acetate. It is suggested that the polymers degrade by radical chain mechanisms, and a number of possible elementary steps are proposed.
Degraded products in weathered polymers
Authors: Shimura Yukio
Published: April 2003

Styrene–methyl vinyl ketone copolymers, methyl methacrylate–methyl vinyl ketone copolymers, and styrene–methyl vinyl ketone–2,6‐di‐t‐butyl‐4‐acroylaminomethylphenol terpolymers as well as polystyrene and polypropylene have been weathered either by artificial irradiation or by outdoor exposure. The weathered products were analyzed using GC mass spectrometry, liquid chromatography, IR, UV, NMR, and wet analytical methods. Most of the weathered products proved to be low molecular weight polymers with various functional groups, and many low molecular weight compounds were identified. From the degradates of styrene copolymers, acetone, acetic acid, acetophenone, benzoic acid, formic acid, phenol, benzaldehyde, etc., were identified; from the degradates of methyl methacrylate copolymers, acetone, acetic acid, methanol, methyl methacrylate, methyl vinyl ketone, etc., were identified; and from the degradates of polypropylene, aliphatic acids up to propionic were analyzed. In many cases, the most abundant species was acetic acid. From polypropylene weathered outdoors for two years, 1.2 μl/g acetic acid was obtained. The degradates of styrene copolymers were found to contain fluorescent substances.
Viscosity index. III. Thermodynamic parameters for side chain crystallinity in pour point‐modified blends containing n‐octadecyl acrylate
Authors: Jordan Edmund F. , Smith Stephen , Zabarsky Ruth D. , Wrigley A. N.
Published: April 2003

The melting transitions and heats of fusion were obtained by differential scanning calorimetry for the crystalline phase of the same mixtures whose rheological properties were reported in the previous two papers. Pour point temperatures were also determined. In addition, the same thermodynamic quantities were also collected for higher polymer concentrations in this work, thus encompassing the entire concentration range. The DSC scans revealed that the distribution of crystallite sizes characteristic of the bulk copolymers was retained in the blends. Phase diagrams indicated isomorphism in all systems studied. An equation was derived to predict the influence of diluent concentration on melting point depression of copolymers, in which one component crystallizes through its side chains but in which the side chains of the other remain amorphous. The difference between the experimental heats of fusion and the value for entirely crystalline poly(n‐octadecyl acrylate) were used to estimate extent of apparent cocrystallization of the different copolymers with the base oil. While this tended to increase with pour point‐depressant ability, concomitant crystallinity of wax and depressant were essential to successful wax crystal modification. A mechanism is proposed in which whole molecules of hexagonally packed copolymers are attached to wax nuclei and accumulate slowly a t low diffusion rates. Thus, growth occurs over small crystal areas and is considered responsible for the directing influence of copolymer depressant. The resulting small crystal sizes, accompanied by fast growth of rapidly diffusing paraffins on uncontaminated surfaces, promote more compact habits, like dendrites that postpone network formation to lower temperatures. It was concluded that a melting point difference of less than 25°C between bulk copolymer and base oil is required for successful pour point depression. Consequently, in this base oil, only copolymers with long amorphous side chains in a limited composition range, such as the n‐octadecyl acrylate–2‐ethylhexyl acrylate copolymers, possessed sufficient lattice disorder to meet the specification. The rest produced gelation at higher temperatures.
Permeability of poly‐L‐methionine membrane and its oxidized membrane to water vapor
Authors: Minoura Norihiko , Fujiwara Yukihiko , Nakagawa Tsutomu
Published: April 2003

The permeability of poly‐L‐methionine (PLM) membrane and its oxidized form to water vapor was studied. Permeability coefficients of the PLM membrane were large, of the order of 10−7 cm3 (S.T.P.)·cm/cm2·sec·cm Hg. The sorption and permeation behavior of the PLM membrane was hydrophobic. The oxidized membrane was prepared by treating one or both sides of the PLM membrane with an aqueous solution of hydrogen peroxide. The membrane oxidized from one side is probably not layered but has a gradient of composition from one surface to the other. The amounts of water sorbed by the modified membrane increased with increase in oxidation time. The permeability coefficients of water vapor through the modified membrane were of the order of 10−6 cm3 (S.T.P.)·cm/cm2·sec·cm Hg.
Interrelation of mechanical and optical properties of plasticized epoxy polymers
Authors: Theocaris P. S. , Prassianakis J.
Published: April 2003

A series of cold‐setting epoxy polymers, plasticized with different amounts of plasticizer, ranging between 0 and 90% by weight of the amount of the epoxy prepolymer, were studied for their mechanical, optical, and fracture behavior properties. Quantities defining the mechanical properties were considered: the elastic modulusE, Poisson's ratiov, and fracture tensile stress σf. These were accurately measured with electric strain gauges in specimens tested in a 5‐ton Instron tester. The optical behavior was characterized by the stress optical coefficients of the materials in both principal directions, α and β, as well as by the coefficient of optical anisotropy, ζ. The values of these quantities were measured by a Fizeau interferometric method. Finally, the optical method of caustics was applied to cracked epoxy polymer specimens to provide a new experimental technique for determining the stress optical properties of these polymers in terms of their mechanical properties. This method was used to check the previous results found by established experimental methods.
A thermomechanical investigation of highly cold‐drawn polycarbonate
Authors: Kato T. , Kambe H.
Published: April 2003

A new technique detecting molecular motions in drawn polymers was applied to highly cold‐drawn polycarbonate of bisphenol A. It is shown that the sample exhibits thermal shrinkage in three steps with the temperature increase up to above the glass transition temperature. The molecular relaxation at the highest temperature is due to the glass transition. The other two molecular motions at the lower temperature are those of main chain in the glassy state and they correspond to the molecular motions as revealed in dielectric measurement by Sacher.1 By using the general theory of the thermal analysis by Ozawa,2 the apparent activation energies of these molecular motions were obtained: for the highest temperature 110 kcal/mole, and for the lowest temperature, 33.5 kcal/mole. The impact strength and the cold workability of this polymer are also discussed in relation to these molecular motions.
A unified concept of melt flow instability during extrusion
Authors: Lenk R. S.
Published: April 2003

The mechanism of melt flow instability at drawdown rates below and up to that necessary to compensate for die swell and at drawdown rates exceeding the former is explained with the aid of diagrams and appropriate comment. It is suggested that there is no fundamental difference between the causes of commonly encountered extrudate defects and “draw resonance” which appears in fiber spinning at excessive drawdown rates. It is argued that both are manifestations of viscoelastic phenomena which affect extrudate appearance either not at all due to effective suppression or which give rise to defects of increasing severity when control of the process—including die design and proper consideration of the forces at the die/melt interface—is inadequate.
Preparation of modified poly(vinyl chloride) containing N,N‐di(β‐hydroxyethyl)dithiocarbamate and its reaction with metal ions
Authors: Hiratani Kazuhisa , Matsumoto Yoko , Nakagawa Tsutomu
Published: April 2003

Reaction of N,N‐di(β‐hydroxyethyl)dithiocarbamate ion with poly(vinyl chloride) (PVC) was undertaken, and the reaction with metal ions of the polymer obtained was investigated. The effect of γ‐irradiation on the reaction with metal ion was also studied. The modified PVC (PHDC) obtained from the reaction with N,N‐di(β‐hydroxyethyl)dithiocarbamate ion is pale yellow even after reaction at 100°C for 5 hr in dimethylformamide (DMF); it is soluble in dipolar solvents and its chlorine content is decreased considerably. This polymer reacted well with acetate salts of copper(II), nickel(II), zinc(II), and silver(I) heterogeneously in aqueous solution because of the introduction of hydrophilic groups (two hydroxy groups). The reactivity of the metal ions toward the polymer was of the order Ag(I) ≫ Cu(II) > Ni(II) > Zn(II). From the result of the reaction of γ‐irradiated polymer with cupric ion, the polymer was judged to have fairly good antiradiation property.
Ignition properties of polymers evaluated from ignition temperature and ignition limiting oxygen index
Authors: Morimoto Takayoshi , Mori Takashi , Enomoto Susumu
Published: April 2003

An apparatus for measuring ignition temperature and ignition‐limiting oxygen index was devised in order to study ignition properties of polymers. Ignition limiting oxygen index, which was suggested by the limiting oxygen index (ASTM D2863‐70), was defined as the minimum volume fraction of oxygen required for ignition to occur in a slowly rising gaseous atmosphere. The ignition temperatures and the ignition limiting oxygen indexes of typical polymers were measured by this apparatus. Polymers which produced more ethylene by pyrolysis tend to have lower ignition temperatures. In the case of the same kinds of polymers, plots of ignition temperatures versus ignition limting oxygen indexes gave nearly straight lines (Fig. 3), but the straight line of depolymerization‐type polymers differed from that of random degradation‐type polymers differed from that of random degradation‐type polymers. In most polymers, ignition limiting oxygen indexes were nearly proportional to limiting oxygen indexes, but in the cases of hard poly(vinyl chloride) and soft poly(vinyl chloride), the plots did not follow this relation (Fig. 4). Ignition properties of self‐extinguishing polymers were also studied.
Effects of sterilization procedures on the tensile properties of polycarbonate
Authors: Weyers R. E. , Blankenhorn P. R. , Stover L. R. , Kline D. E.
Published: April 2003

The tensile properties of polycarbonate were investigated for specimens subjected to three sterilization procedures—(autoclaving, gassing, and gamma irradiation). Generally the tensile modulus decreased and the percent elongation at yield increased for all sterilization procedures. The ultimate stress was decreased by the ethylene oxide and gamma radiation procedures, while it was increased by the autoclave procedure. The total elongation at break generally increased with all sterilization procedures investigated. For repeated sterilizations, it appears that the autoclave procedures would be less detrimental to the tensile properties of polycarbonate, particularly if the maximum sterilization temperature does not exceed 260°F (127°C). Any of the sterilization methods described can probably be used on polycarbonate for a single application, although the autoclave and gamma sterilization procedures appear to be somewhat better than the gas sterilization procedures in relation to the tensile properties.
Photochemical reactions in commercial poly(ethylene 2,6‐naphthalate)
Authors: Allen N. S. , McKellar J. F.
Published: April 2003

The photodegradation of poly(ethylene 2,6‐naphthalate) is examined by absorption and emission spectroscopy and by flash photolysis techniques. A comparison of the emission spectra with that of a model compound 2,6‐dimethynaphthalate (DMN) shows that the chromophoric species responsible for light absorption in the near ultraviolet is the unit structure of the polymer itself. A flash photolysis study of DMN indicates that the major primary process in photodeterioration of the polymer involves scission by decarboxylation at the naphthyl‐carbon bond.
UV screen progenitors. Thermally labile urethane derivatives of hydroxyphenylbenzotriazoles and hydroxybenzophenones
Authors: Olson Daniel R. , Schroeter Siegfried H.
Published: April 2003

UV‐curable formulations do not UV cure when hydroxybenzophenone or hydroxyphenylbenzotriazole UV screens are added to them. Reaction of these UV screens with alkyl or aryl isocyanates gives urethane derivatives in high yields. These derivatives do not impede UV cures when they are incorporated in UV‐curable formulations at relatively high levels (3%–5%). After completion of the UV cure, the urethane derivatives are catalytically decomposed by heating to regenerate the corresponding UV screen within the cured coating.
Thermal degradation of polymers. Part XIX. The thermal cyclization and characterization of quinazolone pre‐polymers
Authors: Chan H. S. O. , Still R. H.
Published: April 2003

A series of pre‐polymers prepared from 4,4′‐diaminodiphenyl‐3,3′dicarboxylic acid and aromatic diacetamido compounds have been thermally cyclized and their structures have been investigated using infrared spectroscopy, combustion analysis, and weight loss techniques. The structures obtained on cyclization are discussed in terms of concurrent cyclization and decarboxylation reactions resulting in incomplete cyclization. Specific structural features due to the lability of main chain bonds at the cyclization temperatures are also discussed. Dynamic thermogravimetry and isothermal weight loss studies have been used to evaluate thermal stability and kinetic parameters. The results are discussed in terms of the overall complexity of the polymer structure and the complexity of the degradation process. It is concluded that in such systems, where the structural variations are large, it is not possible to define a meaningful stability sequence because like systems are not under comparison.
Effect of ethanol–water mixture as gelation medium during formation of cellulose acetate reverse osmosis membranes
Authors: Tweddle T. A. , Sourirajan S.
Published: April 2003

By using ethanol–water mixtures in a wide range of alcohol concentrations and temperatures, cellulose acetate membranes with a wide range of surface porosities can be obtained. Two different casting solution compositions were used, involving cellulose acetate, acetone, and aqueous magnesium perchlorate (composition I) or formamide (composition II). All reverse osmosis experiments were carried out at 250 psig using a 3500 ppm NaCl–H2O feed solution at laboratory temperature. The effective area of film surface was 12 cm2 in all cases. With composition I, with pure water gelation medium at 0°C, the resulting membrane gave a solute separation of 5% and product rate of 220 g/hr, whereas with 95% alcohol as gelation medium, the resulting membrane gave a solute separation of ∼1% and product rate of 1240 g/hr under otherwise identical experimental conditions. With composition II membranes, the maximum product rate of 360 g/hr with the corresponding minimum solute separation of ∼1% was obtained with 71.2% alcohol–water gelation medium at 0°C. Increase in the temperature of the gelation medium in the range 12° −25°C tends to increase the average size of pores on the membrane surface. These results offer a basis for the development of cellulose acetate ultrafiltration membranes.