bluuebunny/crossref_metadata_2025_split huggingface dataset:
The ultraviolet activation spectrum of polycarbonate
Authors: Mullen P. A. , Searle N. Z. 
Published: April 2003

AbstractPrevious work has shown that a polymeric phenyl salicylate and a polymeric dihydroxybenzophenone are formed during the irradiation of polycarbonate with nonspectrally dispersed ultraviolet light. In the present studies the photodegradation of polycarbonate film has been investigated as a function of irradiating wavelength using spectrally dispersed light from a xenon are between 2300 and 6300 Å. Maximum changes in absorbance at 3200, 3600, and 4000 Å were induced in the sample by irradiating wavelengths between 2800 and 2900 Å. The wavelength sensitivity of an extruded sample of polycarbonate is compared with results obtained for a solution‐cast thin film of the material. The results of the present study support the stepwise photodegradation mechanism of polycarbonate previously reported and suggest the possibility of an additional photodegradation process.
Cellulose graft copolymers. II. Graft copolymerization of ethyl acrylate with γ‐irradiated cellulose from acetone–water systems
Authors: Nakamura Yoshio , Hinojosa Oscar , Arthur Jett C. 
Published: April 2003

AbstractEthyl acrylate was graft‐copolymerized from acetone–water systems with γ‐irradiated, purified cotton cellulose. The scavenging of the free radicals in the irradiated cellulose by water, acetone, and water–acetone systems was determined by electron spin resonance spectroscopy. The ESR spectra of free radicals, scavenged by water and acetone, were recorded by the use of a time‐averaging computer attached to the ESR spectrometer, in which the ESR spectrum of the irradiated cellulose, which had been immersed in water and/or acetone, was electronically subtracted from the ESR spectrum of the irradiated cellulose control. For both water and acetone, the ESR spectra of the scavenged free radicals were singlets. This indicated that free radical sites formed on carbon C1 or C4 on radiation‐initiated depolymerization, which would generate singlet ESR spectra, were readily accessible to these solvents. The maximum scavenging of the radicals was observed when irradiated cellulose was immersed in acetone–water solution which had a composition of 25/75 vol‐%. The scavenging of the free radicals in irradiated cellulose when immersed in acetone–water solutions was less than when immersed in methanol–water solutions. Also, the extent of graft copolymerization of ethyl acrylate from acetone solutions with irradiated cellulose was less than that of ethyl acrylate from methanol solutions. These differences were probably due to differences in the diffusion rates of acetone and methanol into the cellulosie structure. The Trommsdorff‐type effect in the acetone solutions would be less than in the methanol solutions, since acetone is a better solvent for poly(ethyl acrylate) than methanol.
Reversible crosslinking in cellulose. II. Mono‐and bifunctional reactions of bis‐β‐isocyanatoethyl disulfide with cotton
Authors: Sakamoto Munenori , Takeda Junichi , Yamada Yoshio , Tonami Hiroaki 
Published: April 2003

AbstractBis‐β‐isocyanatoethyl disulfide (BIED) was synthesized from diethyl dithiodipropionate and its reaction with cotton in dimethylformamide was investigated. The sulfur content of the treated cotton decreased by reduction with tri‐n‐butylphosphine. The polarographic and infrared analyses revealed that BIED reacted with cotton both monofunctionally and bifunctionally to form branches and crosslinks, respectively. The ratio of the crosslinks to the total amount of BIED combined increased in general as the reaction progressed. X‐Ray study indicated that the reaction took place mainly in the original amorphous region.
The degradation of polystyrene during extrusion
Authors: Arisawa Kunio , Porter Roger S. 
Published: April 2003

AbstractAn investigation was made of the magnitude and mechanism of shear degradation of a narrow distribution, high molecular weight (Mw = 670,000) polystyrene. An Instron rheometer was used to perform the extrusion at temperatures from 164° to 250°C. The change in molecular weight distribution was studied by gel permeation chromatography. The maximum shear stress employed was 5.83 kg/cm2. It was found that degradation could be induced at high stress at temperatures of 50°C lower than degradation of polystyrene would occur exclusively due to thermal forces. An activation energy for the degradation, calculated at constant shear rate, was +20.2 kcal/mole. The direction and magnitude of this value are consistent with degradation induced through a mechanical reduced activation for thermal degradation.
Mechanism of alkali thickening of acid‐containing emulsion polymers. I. Examination of latexes by means of viscosity
Authors: Verbrugge C. J. 
Published: April 2003

AbstractViscosity‐versus‐pH relationships for a large number of methacrylic acid‐containing emulsion polymers have been measured. The monomers chosen for this study were so selected because they represent synthesized latexes of high and low Tg and comparative hydrophilicity. These were styrene, methyl methacrylate, ethyl acrylate, n‐butyl acrylate, and 2‐ethylhexyl acrylate. The postulated mechanism involved in the transition from an unneutralized latex particle to the neutralized species is accounted for in terms of varying degrees of particle swelling. In the limiting case, particle swelling is followed by complete solution of the polymer. The most important variables are the per cent methacrylic acid and the polymer Tg and hydrophilicity as determined by the comonomers present. The degree of particle swelling ranges from none for high styrene‐containing latexes to high degrees of swelling followed by polymer solubilization for high ethyl acrylate‐containing latexes.
Mechanism of alkali‐thickening of acid‐containing emulsion polymers. II. Examination of latexes with the light microscope
Authors: Verbrugge C. J. 
Published: April 2003

AbstractThe mechanism of alkali thickening of acid‐containing emulsion polymers has been confirmed by visual examination of the swelling and disappearance of latex particles with the light microscope. Specially prepared large particle‐sized latexes were used in this study. Each latex was examined from 0%–200% neutralization with base. The particle swelling and dissolution behavior correlated with viscosity measurements, high viscosity being present for swollen particle systems and low viscosity for true solutions. The neutralized state of all acid‐containing latexes can be pictured in a cube with the important variables being per cent acid, hydrophilicity of the comonomers, and Tg. At the bottom will be latexes only slightly affected by neutralization, above this will be a swollen particle zone, and the largest area will be a true solution zone. The true solution zone will be enlarged by lowering the molecular weight of the latex polymer.
Rheological properties of elastomers based on cellulose fibers
Authors: Nakamura Y. , Arthur Jett C. , Negishi M. , Doi K. , Kageyama E. , Kudo K. 
Published: April 2003

AbstractElastomers, based on cellulose fibers, were synthesized by grafting ethyl acrylate onto fibers preirradiated by a high‐energy electron beam. The rheological properties and fine structure of the elastomers were investigated in order to determine factors in development of rubber‐like elastomeric behavior. Mechanical properties of the elastomers depended on (1) degree of polymerization of irradiated cellulose molecules, (2) extent of grafting, and (3) experimental methods of evaluation, particularly in varying environmental conditions, for example, in making measurements in air, water, or ethyl acetate. Glass transition temperatures of the elastomers were dependent on the environmental conditions of evaluation; stiffnesses of the elastomers levelled off at about 0°C; and in all environments, a rubber‐like plateau was observed. Poly(ethyl acrylate) separated from the elastomers was not soluble in acetone. The mean molecular weight of the separated poly(ethyl acrylate) of the elastomer was determined in ethyl acetate by the equilibrium swelling method. It was concluded that crosslinks existed in the elastomers. Electron microphotographs of cross sections of the elastomers, which exhibited rubber‐like behavior, indicated that the fibrillar structure of the irradiated cellulose fibers formed a uniform network and that poly(ethyl acrylate) was uniformly distributed among the fibrils.
Effect of tensile strain on the use of the WLF equation
Authors: Adicoff Arnold , Lepie Albert H. 
Published: April 2003

AbstractThe effect of finite elongation on superposed infinitesimal torsional oscillations has been determined on two propellants, a carbon black‐filled rubber and Solithane 113 (Galcit I), as a function of temperature at various fixed frequencies. Torsional storage modulus—temperature data for carbon black‐filled rubber and propellant show that the effect of the imposed tensile elongation cannot be explained by any simple temperature–elongation shift relationship. The shift factors for the torsional moduli of these two polymeric systems have been calculated as a function of temperature at various tensile elongations. The WLF constants C1 and C2 have been computed for these systems as a function of the elongation. The constants decrease with increasing elongation. The values of the constants at 0% elongation are larger than those commonly found in unfilled materials. The temperature dependence of the shift factor of the torsional storage modulus was found to differ from that of the loss modulus in the cases of carbon black‐filled rubber and propellant. This difference is slight for the rubber and large for the propellant. The effect of increased elongation is to increase the difference in the shift behavior of the moduli for each of these filled polymers. The shape of the loss tangent curve of the propellants examined indicates that these propellants are not thermorheologically simple.
The adsorption and absorption of water vapor by polyethylene terephthalate
Authors: Prosser R. A. 
Published: April 2003

AbstractAn experimental technique for the simultaneous determination of the amount of gas or vapor absorbed and adsorbed by a film of material is given. For Mylar film at 40°C it was found that the amount of water at an activity of 0.9 that was adsorbed was about 1 × 10−7 g/cm2. Assuming that a water molecule is cubical in shape and 3.26 Å on an edge and the surface is geometrically flat, this amounts to several layers of water molecules on the surface for any thickness.
Copolymer characterization by surface tension
Authors: Allan G. Graham , Neogi Amar Nath 
Published: April 2003

AbstractThe use of surface tension measurements is proposed as a simple method for the determination of copolymerization ratios. The procedure depends on the parachor of the copolymer in the liquid state (∏), which is defined by ∏ = ∏s + ∏0(wp/ws)(Ms/M0) for solutions and ∏ = [DP]∏0 for liquid or molten polymers, where ∏s is the parachor of the solvent of molecular weight Ms; wp and ws are the weights of the polymer and solvent in solution; while ∏0 and M0 are the parachor and molecular weight of the repeating unit of the copolymer, respectively. The validity of this relationship is demonstrated by analysis of the surface tension properties of liquid silicone polymers, polystyrene–Decalin solutions, and molten polymers as well as by the calculation of the composition of some characterized tetrahydrofuran–propylene oxide copolymers. The application of surface tension measurement is also suggested as a means of estimating the degree of chain branching in a polymer.
Effects of mixing states on physical properties of vulcanizates of polybutadiene rubber‐general purpose polystyrene resin blend
Authors: Satake K. 
Published: April 2003

AbstractThe effects of the continuous phases of general purpose polystyrene resins upon the physical properties of the vulcanizates were studied using the polybutadiene rubber–general purpose polystyrene resin blend. The unvulcanized samples were prepared according to the method already mentioned in our previous report,1 and the radiation cure was adopted so that a change of state during cure might be avoided. Some physical properties like hardness, modulus, elongation, permanent set, and resilience are much influenced by the existence of the continuous phases even if the polymer blend ratios are kept constant, whereas tensile strength at failure is mainly determined by the polymer blend ratio. The physical properties which belong to the former group are found to be controlled more strongly by the polymer which forms the continuous phase.
Some filler effects on diffusion in silicone rubber
Authors: Most C. F. 
Published: April 2003

AbstractThe diffusion of ethyl p‐aminobenzoate in silicone rubber membranes containing varying amounts of a high surface area fumed silica filler is described, as is a new apparatus for assaying multiple samples. It is shown that increased filler loading results in what appears to be a linear decrease in transmission rate, but that apparent diffusivities fall off drastically as a result of adsorption of the permeant on the filler. Distribution coefficient measurements suffer from the same result. The results suggest that neither an unmodified time lag technique nor a direct solubility method can be used to determine diffusivities of polar or unsaturated molecules in silicone rubbers, since they generally contain silica fillers.
Composition of methyl methacrylate‐grafted cellulose
Authors: Ogiwara Yoshitaka , Kubota Hitoshi , Arai Kenichiro 
Published: April 2003

AbstractGraft copolymerization of methyl methacrylate on cellulose samples was carried out using various initiator systems, and extraction treatment was performed on the copolymers with 50% to 300% grafting by weight. Adding of ceric ion to a suspension of cellulose and methyl methacrylate in water resulted in more efficient grafting than other methods. That is, amount of extracted cellulose from graft copolymers obtained by the conventional ceric ion method was approximately 20%, whereas those obtained either by the hydrogen peroxide method or by the adsorbed ceric ion method amounted to 70% to 80%. However, the amount of extracted homopolymer was approximately proportional to that of extracted cellulose. The composition of refined samples ranged 20% to 30% of cellulose content and 70% to 80% of poly(methyl methacrylate) content throughout all samples, and it was recognized that the proportion of poly(methyl methacrylate) tended to increase slightly with higher per cent grafting. When the structure of refined graft copolymer was derived from these values, it was recognized that the extent of the grafted chain was at most 1 mole per 1 mole of cellulose molecule in the conventional ceric ion method and amounted to only 1/10 mole in the hydrogen peroxide and adsorbed ceric ion methods.
The average molecular structure of base‐catalyzed low‐mole adducts of propylene oxide to glycerin
Authors: Gibson U. H. , Quick Q. 
Published: April 2003

AbstractThe average structure of low molecular weight base‐catalyzed propylene oxide adducts of glycerin have been studied rather extensively using gas chromatographic and HNMR techniques. HNMR analysis of the trifluoroacetyl derivatives of individual adducts provide a useful technique for distinguishing internal isopropoxy units from terminal isopropoxy units. It can also be used to estimate the degree of initiation at the secondary hydroxyl site of the glycerin starter. A surprising amount of initiation at the secondary hydroxyl site was found for the three‐mole adducts and the four‐mole adducts are very highly initiated at this site. Concentrations of the possible contributing structures in fractions of a typical low‐mole weight polyol are tabulated. The higher adducts are envisioned as consisting of three propagating chains of nearly equal length and reactivity.
Dichroism of poly(ethylene terephthalate)‐disperse dye system
Authors: Okajima Saburo , Nakayama Kazuo , Kayama Kazuo , Kato Yoshio 
Published: April 2003

AbstractAs an approach to the basic study on the orientation behavior of amorphous region, the dichroic orientation factor, D, of poly(ethylene terephthalate), PET, fiber or film dyed with disperse dyes was investigated in relation to Δn, birefringence of the crystalline and amorphous regions, and Δna, birefringence of the amorphous region. It was found that D versus Δn plot belonged to a linear relationship passing through the origin but breaking slightly toward the D axis at Δn ≃ 0.14, while D versus Δna plot was expressed by a straight line passing similarly through the origin but with no break. D0, the value of D at the ideal parallel orientation, was obtained by extrapolating the latter plot of the samples stretched with no relaxation: 1.00 and 0.73 for the PET–C.I. Disperse Yellow 7 and PET–C.I. Disperse Red 17 systems respectively. When the sample had been relaxed, the D versus Δna was also linear; however, D0's obtained were smaller than the above mentioned respective values. Even in these cases D for Disperse Yellow 7 versus the corresponding D for Disperse Red 17 belonged to a linear relationship with the slop 1:0.73.As the result it was concluded that the transition moment of molecule of C.I. Disperse Yellow 7 coincided with the molecular axis and the dye molecule combined parallel to PET chain, while as to C.I. Disperse Red 17 any definite conclusion could not be determined. However, in the both cases the mode of combination of dye molecules with PET is definite and kept unchanged during stretching and heating.
Preparation of a polyimide foam
Authors: Farrissey William J. , Rose James S. , Carleton Peter S. 
Published: April 2003

AbstractThe reaction of phenyl isocyanate with phthalic anhydride to form N‐phenylphthalimide is strongly solvent dependent and catalyzed by tertiary amines. Water and alcohol promote imide formation, but Lewis acids and organometallic compounds are ineffective. In DMSO solvent, benzophenone tetracarboxylic dianhydride (BTDA) and polymethylene polyphenol isocyanate (PAPI) polymerize with the evolution of carbon dioxide to yield a foamed polyimide. The solvent‐freed open‐celled foams exhibit exceptional fire resistance and thermal stability.
The molecular weight of a sodium lignosulfonate in dimethylsulfoxide and in aqueous 0.1M sodium chlorine
Authors: Yean W. Q. , Goring D. A. I. 
Published: April 2003

AbstractValues of the weight‐average molecular weight for a high molecular weight lignosulfonate were found to be nearly equal in aqueous sodium chloride and in DMSO. Prolonged storage in DMSO produced no perceptible change in molecular weight. The results indicated that the lignosulfonate macromolecule was a truly covalent species and was not an aggregate comprised of many low molecular weight units held together by association forces.
The fracture threshold for an adhesive interlayer
Authors: Williams M. L. 
Published: April 2003

AbstractComplementing an earlier paper which utilized an energy balance criterion for a continuum mechanics analysis of adhesive failure in a pressurized blister at the interface of an elastic material and a rigid substrate, the analysis is extended to include an additional elastic interlayer between them. An infinite lateral‐length elastic plate strip bonded through a Winkler elastic foundation to a rigid substrate is assumed, in which the plate is separated from the adhesive layer by internal pressure. It is found that the important design parameters are the tensile modulus‐to‐thickness ratio of the adhesive layer and the adhesive fracture energy of separation of the respective materials. The results provide a basis for investigating changes in the chemical microstructure of the adhesive.
Creep and stress relaxation of natural rubber vulcanizates. Part I. Effect of crosslink density on the rate of creep in different vulcanizing systems
Authors: Farlie E. D. 
Published: April 2003

AbstractThe physical creep of unfilled natural rubber vulcanizates, prepared with different vulcanizing systems, has been studied. For each of the three vulcanizing systems chosen there is a strong dependence of creep rate on crosslink density, but the rates for accelerated sulfur vulcanizates are two or three times higher than those of peroxide vulcanizates of similar crosslink density. Supplementary experiments, in which the crosslink structure of sulfur vulcanizates is modified either by chemical treatment or by variations in the vulcanizing conditions, show that the nature of the crosslink itself is not a determining factor in the type of vulcanizate. Other features, such as the type and quantity of extranetwork material arising from the vulcanizing process, contribute significantly to the viscoelastic behavior of accelerated sulfur vulcanizates.
Determination of poly(oxypropylene diol) present in poly(oxypropylene triol) by thin‐layer chromatography
Authors: Mameniskis Walter A. 
Published: April 2003

AbstractA thin‐layer chromatographic method has been developed for the quantitative determination of poly(oxypropylene diols) present in poly(oxypropylene triols). The polyols are separated on silica gel plates in a modified developing chamber using ethyl acetate as the developer. Quantitative results were obtained by conventional visualization and densitometer techniques. Polyols ranging in average molecular weight from 400 to 3000 have been resolved by this method. Diols present in a mixture with triols can be detected at levels as low as 1.0%.
Ultrafiltration of macromolecular solutions with high‐flux membranes
Authors: Baker R. W. , Strathmann H. 
Published: April 2003

AbstractBatch and flow recirculation cells were used to study the properties of high‐flux ultrafiltration membranes with different macromolecular solutions. At low pressures, solutions of completely retained macromolecular solutes have a flux which is approximately the same as the flux of pure solvent. At higher pressures, the solution flux levels off. The flux, at the leveling‐off period, is approximately inversely proportional to the solution concentration. In this plateau region the flux increases with temperature and agitation of the solution but decreases with time. These results are explained by the formation of a gel layer on the membrane surface during the filtration of macromolecular solutions. In ultrafiltration, in contrast to dialysis and GPC, a linear polymer penetrates the selective barrier more readily than does a globular protein of the same molecular weight. The difference may arise from the liquid shear stresses within the barrier medium due to the movement of fluid relative to the pore walls, which is large only in ultrafiltration. Also, retention of polymers was found to decrease with pressure and to increase with agitation of the solution.
Studies in chemically modified celluloses. III. Estimation of free carboxylic acid groups in oxycellulose
Authors: Nabar G. M. , Shenai V. A. 
Published: April 2003

AbstractVarious methods suggested for the determination of carboxyl groups in chemically modified celluloses suffer from some drawbacks. Attempts have been made to overcome the drawbacks of some of these methods. The influence of alkali‐sensitive reducing groups, enediol groups, and lactones on the carboxyl estimation is discussed and the importance of borohydride treatment of the oxycelluloses before the estimation of carboxyl groups by alkali titration method or by iodometric method is stressed. The usefulness and the limitations of both methods are pointed out.
The anionic dispersion polymerization of α‐methylstyrene
Authors: Stampa Guido B. 
Published: April 2003

AbstractA new technique for the anionic polymerization of α‐methylstyrene has been developed. By using an aliphatic hydrocarbon as the diluent, hexamethylphosphoramide as promoter, and a poly(vinyl alkyl ether) as interfacial agent, the high molecular weight polymer is obtained as a uniform dispersion. The advantages of the method are high conversions at low viscosities and an economical isolation procedure.