bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photooxidation of polystyrene: Irradiation at 254 and 365 nm
Authors: Otocka E. P. , Curran S. , Porter Roger S. 
Published: April 2003

AbstractStudies have been made of the near surface photooxidation of atactic polystyrene films prepared in the absence of air. The samples were photooxidized on exposure to air at two frequencies, 254 and 365 nm, using a calibrated mercury irradiation source with filters. Most studies were made at 40°C and as a function of irradition time with the reactions characterized by changes in molecular weight and composition. The former was evaluated by gel permeation chromatography and the latter by transmission Fourier transform infrared spectroscopy and by multiple‐internal‐reflectance infrared spectra using different angles and different crystals to evaluate compositions as a function of film depth. Species identified in photooxidation include the generation of hydroperoxides and the appearance of carbonyl bands with the latter identified by the spectral shift asociated with the exposure of the photooxidized polystyrene surface to ammonia. These results suggest that principal products of near‐surface oxidation of polystyrene are carboxylic acids.
Toughened polystyrene containing high cis‐1,4‐polybutadiene rubber
Authors: Sardelis K. , Michels H. J. , Allen G. 
Published: April 2003

AbstractHigh cis ‐1,4 ‐polybutadiene has been used to prepare toughened polystyrene in an attempt to improve its low temperature impact properties. A range of physical and mechanical properties was obtained by keeping the amount of rubber and the polymerization conditions constant, and varying the rate of agitation in a purpose ‐built reactor system. Although a good balance of tensile and impact properties is obtained at room temperature, the rubber partially crystallizes when the polyblends are cooled to below −40°C. This should decrease the efficiency of rubber particles to create and terminate crazes. However, it is significant that the developed crystallinity decreases with the rubber phase volume, and is suppressed almost completely at about 21% rubber phase volume (RPV). The factors influencing the RPV are discussed, and a study of the phase inversion with three different types of rubber shows that its duration depends on the viscosity of the styrene/rubber system.
Physical aging in particulate‐filled composites with an amorphous glassy matrix
Authors: Yilmazer Ulku , Farris Richard J. 
Published: April 2003

AbstractPhysical aging was studied on particulate ‐filled glassy network polymers by means of mechanical ‐dilatational, differential scanning calorimetry (DSC) and density measurements on specimens that were aged at room temperature. The composites aged for 0.5 day fractured in a brittle manner at a constant ultimate stress, which is close to the tensile strength of the unfilled material, regardless of the filler content and the presence of a coupling agent. This type of mechanical behavior is caused by the compressive residual stresses that are present due to curing and differential thermal shrinkage. As aging takes place, the compressive residual stresses are relieved; as a result the ultimate tensile strengths of the composites decrease. The 120 ‐day ‐old untreated glass bead containing composites exhibited dilatation and yield in mechanical ‐dilatational testing. This type of behavior is described as “having no adhesion” between the filler and the matrix. The 120 ‐day ‐old composites with coupling agent ‐treated glass beads fractured at a tensile stress which is equal to 1/1.6 the tensile strength of the unfilled material. These materials did not exhibit dilatation and yield in mechanical ‐dilatational testing. Density and DSC data indicate densification and enthalpy relaxation upon again and support the hypothesis presented for the observed change in the mechanical ‐dilatational behavior.
Effect of reinforcing carbon black on network structure, technical properties, and failure mode of EPDM rubber
Authors: Pal Pranab K. , De S. K. 
Published: April 2003

AbstractThe high sulfur (HS) vulcanization system gives rise to higher apparent crosslink density and improvement in modulus, resistance to abrasion, compression set, heat buildup, rebound resilience, and dynamic set than that of the low sulfur (LS) vulcanization system. Tensile strength, tear strength, and flexing resistance were found to be better for the low sulfur (LS) vulcanization system. Rupture energy during tensile and tear failure determined from the Universal Testing Machine (Instron 1195) also reveals a similar phenomenon. Studies on fracture mode during different types of failure have been done by using a scanning electron microscope (SEM).
Effect of stabilizer type on the physicochemical properties of rigid PVC. III
Authors: Aboul‐Gheit A. K. , El‐Hennawi I. M. , Mohsen R. , Younan M. Y. A. 
Published: April 2003

AbstractThe crystallinity of rigid PVC specimens, stabilized by a tin mercaptide or a lead stabilizer, has been studied. It is found that the crystallinity of rigid PVC is greatly influenced by the type of stabilizer added, and that the response of the PVC toward subsequent UV exposure was also different. The effects of unstable structures and crystallinity, after UV irradiation, on the mechanical properties of rigid PVC have been investigated.
Applied macroinorganics. IV. Effect of the crosslinking agent on protonation, and metal ions complexing abilities, of ion exchange resins with poly(amido–amine) structure
Authors: Pesavento M. , Soldi T. , Ferruti P. , Barbucci R. , Benvenuti M. 
Published: April 2003

AbstractTwo classes of resins, having a poly(amido–amine) structure, have been synthesized. The basicity constants and the complexing abilities toward copper (II) and nickel (II) ions have been investigated by potentiometric techniques. The influence of the nature of the crosslinking agent on the basicities and the complexing abilities has been studied.
Effects of coupling agents on the rheological behavior and physical/mechanical properties of filled nylon 6
Authors: Luo Hong‐Lie , Han Chang Dae , Mijović Jovan 
Published: April 2003

AbstractAn investigation was made on the rheological behavior and physical/mechanical properties of highly filled nylon 6 composites with and without a coupling agent. As fillers, calcium carbonate and calcium silicate were used, and, as coupling agent, two silanes (Union Carbide, A1100 and Y9187) and two titanates (Kenrich Petrochemicals, KR‐44 and KR‐138) were used. It was found that all the coupling agents used increased the viscosities of the nylon/CaCO3 system. However, the effect of the coupling agents on the viscosity of the nylon/CaSiO3 system seems quite complex; namely, the titanate KR‐44 decreased the melt viscosity of the nylon/CaSiO3 composite, whereas the titanate KR‐138S and the silane Y9187 increased it. In general, the effectiveness of the coupling agents in improving the physical/mechanical properties of the nylon/CaCO3 and nylon/CaSiO3 composites was marginal. A considerable decrease in glass transition was observed upon exposure of all samples to water, regardless of the type of filler and coupling agent.
Viscoelastic properties of short‐fiber‐reinforced rubber composites and the role of adhesion
Authors: Murty V. M. , De S. K. , Bhagawan S. S. , Sivaramakrishnan R. , Athithan S. K. 
Published: April 2003

AbstractViscoelastic properties of short‐fiber‐reinforced natural rubber composites have been studied as a function of temperature and at different levels of adhesion. The effect of adhesion on the viscoelastic properties of the composites has been assessed, and it is found that the increase in adhesion increases the mechanical loss per cycle and modulus. With the increase in temperature the mechanical loss and modulus drop, indicating a possible deterioration of the adhesion at higher temperatures. Presence of carbon black increases the mechanical loss but does not necessarily increase the level of adhesion. The effect of overcuring has also been studied. Complex modulus of the composites displays an exponential behavior with the increase in volume fraction of fiber.
The preparation of high‐viscosity, partially hydrolyzed polymethacrylamides
Authors: Shepitka J. S. , Case C. E. , Donaruma L. G. , Hatch M. J. , Kilmer N. H. , Khune G. D. , Martin F. D. , Ward J. S. , Wilson K. V. 
Published: April 2003

AbstractDue to the high chain transfer to monomer, the homopolymerization of methacrylamide yields polymers of extremely low molecular weight. On partial alkaline hydrolysis, the viscosities of these polymers in aqueous solution are much inferior to those of partially hydrolyzed polyacrylamide (HPAM). However, polymethacrylamides prepared by room temperature, persulfate‐initiated polymerization in the presence of small amounts of N,N′‐methylenebisacrylamide demonstrate posthydrolysis reduced viscosities in 0.01% NaCl comparable to typical commercial HPAM materials.
Photoinduced graft copolymerization. IX. Graft copolymerization of methyl methacrylate onto nylon 6 in the presence of pyridine–bromine charge–transfer complex as photoinitiator
Authors: Lenka Subashini , Nayak Padma L. , Dash Manoranjan 
Published: April 2003

AbstractPhotoinduced graft copolymerization of methyl methacrylate onto nylon 6 was investigated by using pyridine–bromine (Py–Br2) charge–transfer complex as initiator. The graft yield increased with increasing monomer and initiator concentration at the initial stages, and therefore it decreased. The initiator exponent was computed to be 0.5. The reaction was carried out at three different temperatures, and the overall activation energy was computed. A suitable mechanism has been suggested.
Determination of total short‐chain branching in polyethylenes by computerized data processing of infrared spectra
Authors: Dankovics A. , Füzes L. 
Published: April 2003

AbstractA computer method is described to determine the short‐chain branching of polyethylene from IR spectroscopic data. The shape of the band at 1378 cm−1 (characteristic to the methyl side groups) was calculated by using first a deconvolution procedure (Ishige method) for the envelope curve of the overlapping peaks in the region of 1300‐1400 cm−1, followed by a convolution calculus applied only to the deconvoluted points of the peak in question. The results were in good agreement with values determined by Willbourn's compensation method.
The effect of interfacial adhesion on the tensile behavior of polystyrene–glass‐bead composites
Authors: Dekkers M. E. J. , Heikens D. 
Published: April 2003

AbstractThe tensile behavior at 20°C of polystyrene‐glass‐bead composites has been studied at several glass concentrations. To gain insight into the role of interfacial adhesion, the bonding between glass and polystyrene was varied by using different silane coupling agents. In contrast to the elastic behavior, the crazing behavior of the composites was found to be considerably affected by the degree of interfacial adhesion. This is explained by means of the different mechanisms for craze formation at adhering and nonadhering glass beads, respectively. Furthermore, it was found that both elastic and crazing behavior of the composites are influenced by the glass bead concentration.
Rheology of solvent‐cast polymer films
Authors: Briscoe B. , Smith A. C. 
Published: April 2003

AbstractThis paper describes and analyzes the results of an experiment where various thin polymeric films are continuously sheared between smooth glass substrates. The shear force per unit area has been measured as a function of mean uniaxial stress and temperature using representative “good” and “poor” casting solvents followed by a range of heat treatments. The polymers studied include high density polyethylene, polybisphenol‐A–carbonate, poly(ethylene terephthalate), atactic polystyrene, isotactic polystyrene, atactic poly(methyl methacrylate), isotactic poly(methyl methacrylate), poly(vinyl acetate), poly(vinyl alcohol), poly(vinyl pyrrolidone), poly(vinyl chloride), and polytetrafluoroethylene. The results indicate that the casting solvent has a very pronounced influence upon the rheology of the film. The casting solvents may apparently confer either ductile or brittle failure in the film and also influence the nature of the temperature and pressure dependence of the shear stress. The data have been analyzed using Eyring theory and also by reference to relevant published literature on the influence of solvent and thermal treatments on the morphology and deformation behavior of polymers. “Good” solvents generally tend to promote a brittle mode of failure with little temperature dependence. The same type of solvents also produced films which have higher shear strengths and show greater increases in shear strength with pressure. These data are adequately rationalized using free volume and entanglement notions.
Reaction of 3‐methyl phenol with methyl α‐eleostearate
Authors: Yoshimura Yukio 
Published: April 2003

AbstractThe aromatic ring substitution reaction of 3‐methyl phenol with methyl α‐eleostearate under acidic conditions was carried out. The product was analyzed to find out if 3‐methyl phenol was subjected to the ring substitution reaction with methyl α‐eleostearate at its conjugated double bonds. Up to two molecules of 3‐methyl phenol were addition‐reacted with the conjugated triene of the eleostearyl group of methyl α‐eleostearate. The 4‐position of 3‐methyl phenol was preferentially subjected to the cresol's ring substitution. When 3‐methyl phenol was reacted with a relatively large amount of methyl α‐eleostearate, the substitution reaction occurred at the 6‐ as well as 4‐position of 3‐methyl phenol, to yield a methyl α‐eleostearate dimer having 3‐methyl phenol units in its molecule. The above results were confirmed by infrared (IR), nuclear magnetic resonance (NMR), and high‐speed liquid chromatographic (HLC) analyses, and the results of a previous paper connected with reaction of 3‐methyl phenol were supported by the results of this paper.
Organotin polymers. VII. Copolymerization of triphenyltin methacrylate with some acrylic and methacrylic acid esters
Authors: Ikladious N. E. , Messiha N. N. , Shaaban A. F. 
Published: April 2003

AbstractThe monomer reactivity ratios for the copolymerization of triphenyltin methacrylate with methyl acrylate, ethyl acrylate, and butyl acrylate have been found to be r1 = 2.58, r2 = 0.66, r1 = 2.37, r2 = 0.43, and r1 = 1.27, r0.39 = 0.39, respectively. also, the copolymerization parameters of triphenyltin methacrylate with methyl methacrylate and butyl methacrylate were as follows: r1 = 0.94, r2 = 0.99, and r1 = 0.68, r2 = 0.83, respectively. Copolymerization reactions were carried out in solution at 70°C using 1 mol % AIBN, and the copolymer compositions were determined by tin analysis. The sequence distribution of the alternating diad fractions for the systems studied were calculated at various feed compositions. The structure of the triphenyltin methacrylate monomer as well as its azeotropic copolymer with butyl methacrylate were investigated by IR spectroscopy.
Photochemistry of polymeric systems. VI. Photocrosslinking of basic polymers and copolymers dyeing
Authors: M'Bon Gaston , Roucoux Colette , Lablache‐Combier A. , Loucheux C. 
Published: April 2003

AbstractPoly(N‐vinylamine) (PVAm) and methylmethacrylate/dimethylaminoethylmethacrylate copolymers (MMA/DMAEMA) were prepared and then substituted by cinnamic or cinnamylidene photosensitive groups. The photosensitivity of these materials was determined using the so‐called photoresist test in various experimental conditions. A comparison was made between MMA/DMAEMA and methylmethacrylate/4‐vinylpyridine (MMA/4VP) photosensitized copolymers. The best results were obtained with MMA/DMAEMA on textile support. A photosensitization study was carried out by adding some compounds such as thioxanthone (10% in bulk). It showed that the multiplicity factor can be 10 with MMA/DMAEMA copolymers and even up to 64 for photosensitive PVAm. The addition of anionic dyes on the polymers emphasized that a better fixation occured for aliphatic amines than for pyridinic ones.
Concentration‐induced stress effects in diffusion of vapors through polymer membranes
Authors: Kim Myungsoo , Neogi P. 
Published: April 2003

AbstractThere are two types of anomalous diffusion of vapors in solid polymers which are held to be due to swelling. If the latter is seen as strain, then there must be an accompanying stress which can affect the nature and magnitude of diffusion. The theories of diffusion in polymers are examined in light of the network theory of Larché and Cahn. Their formalism is used to solve permeation and sorption in polymer membranes to illustrate the general features of the elastic effects, particularly the time‐dependent nature of the solubility. That “anomalous” effects will be present is without doubt, considering the concurrent nature of the added elastic effects. However, the present calculations fail to unearth any behavior similar to the case II diffusion. An order of magnitude estimate has been provided which shows that the effects of elasticity are usually significant in rubbery or amorphous glassy polymers where the anomalous effects occur.
Kinetics of swelling of cotton fibers in aqueous ethylenediamine solutions using X‐ray diffraction data
Authors: Chidambareswaran P. K. , Patil N. B. , Pawar A. D. , Shukla S. R. , Lokhande H. T. 
Published: April 2003

AbstractKinetics of swelling of cotton cellulose with 75% (w/w) ethylenediamine (EDA) solution has been studied using X‐ray diffraction. Apparently, the swelling reaction proceeds at three different rates, all obeying the first‐order kinetics. The first rate (k1), which is the fastest one, is hypothetically attributed to the swelling action of EDA–monohydrate in the amorphous region of cellulose; the second rate (k2), which is extremely slow, is responsible for the penetration of swelling species into the crystallites, accompanied by breakage of the hydrogen bonds in these regions; and the third rate (k3), which is faster than k2 but slower than k1, has been assigned to the decrystallization of the crystalline regions. The increase in temperature of swelling (from 10°C to 55°C) brought about increase in all these three rates with shortening of their respective periods. Thus, at temperatures of 35°C and above, k2 and k3 merge, giving a combined rate (k2+3). These results were confirmed from the data on the activation energy values. The changes in crystallinity were comparatively less, when 65% (w/w) EDA solution was used for swelling cotton fibers. The ineffectiveness of 65% (w/w) EDA solution was explained on the basis of the absence of powerful swelling species in the solution. An attempt has also been made to examine the kinetic data on the basis of the model for cotton fiber fine structure consisting of crystalline elementary fibrils and surfaces or regions of varying extents of hydrogen bonding.
Modified Cole–Cole plot based on viscoelastic properties for characterizing molecular architecture of elastomers
Authors: Harrell E. R. , Nakajima N. 
Published: April 2003

AbstractThe types of molecular architecture commonly present in many commercial elastomers include long branching, which in extreme cases results in crosslinked gel network. This architecture was modeled by preparing a series of ethylene–propylene copolymer samples in which the degree of branching was systematically varied. The frequency‐dependent viscoelastic properties of these model systems were measured over a temperature range of 80–230°C with a Rheometrics Mechanical Spectrometer. Time–temperature superposition was employed to obtain master curves of the storage G′ and loss G″ moduli and complex viscosity. The viscoelastic properties of the model samples change systematically with the variations in molecular architecture. Specifically, the low frequency Newtonian viscosity behavior is progressively replaced by non‐Newtonian power‐law behavior, and the G′ response relative to that of the G″ is significantly enhanced as long‐branching increases. The practical use of a modified Cole–Cole plot, in which the axes are expressed as the logarithms of G′ and G″, for analysis of molecular architecture is demonstrated. Changes in the long‐branch architecture of the model samples were readily detected as systematic variations in shape and displacement of the modified Cole–Cole plot. On the other hand, the data of molecularly linear elastomer samples of different Mw but similar MWDs were reduced to a single master Cole–Cole plot.
Diffusion of dyes in polyester fibers. IV. Anomalous sorption of disperse dye synthene scarlet P3GL
Authors: Narȩbska Anna , Lemańska Gizela 
Published: April 2003

AbstractThe investigations on dyeing of poly(ethylene terephthalate) fibers with disperse dye Synthene Scarlet P3GL have revealed anomalous sorption of the dye in heat‐treated samples. In the mathematical solution of the process it has been assumed that anomalous sorption can be treated as superposition in time of two stages of Fickian sorption. The contents of absorbed dye at quasiequilibrium CI, at the final equilibrium CII, and the apparent diffusion coefficients DI, and DII have been calculated using Hill's equation.
Use of photoacoustic spectroscopy in studying the natural weathering of polyethylene films
Authors: Anani Ali , Mobasher Amal , Rasoul Firas A. 
Published: April 2003

AbstractPhotoacoustic spectroscopy was used to assess the degradation of polyethylene under local natural weathering conditions. The results obtained are in good agreement with those obtained using infrared spectroscopy and from mechanical testing. Photoacoustic spectroscopy supports the accepted mechanism of polyethylene degradation.
Microscopic approach to energy dissipation during viscoelastic crack propagation
Authors: Ohtani Nobuo , Kobayashi Akira 
Published: April 2003

AbstractThe microscopic factors relating to the energy dissipation increase in the viscoelastic dynamic crack propagation such as in PMMA [poly(methyl methacrylate)] were investigated through the observation on the microfracture process ahead of the crack tip up to the microcrack formation. It is found that the energy dissipation remains almost constant in a certain low velocity range but increases sharply in the higher velocity range for the PMMA case. A cleavagelike fracture mode works in the former, and both the cleavagelike and a ductile‐fracture mode work in the latter. The increase in energy dissipation is attributed to the secondary cracks which remarkably increase in number depending on the crack velocity. The energy dissipation is proved to be independent of the crack velocity in cases where the crack is propagated by the cleavagelike fracture mode.
Solid foam–polyurethanes with a lowered combustibility
Authors: Troev K. , Todorov K. , Borisov G. 
Published: April 2003

AbstractA composition of solid foam–polyurethane is developed, the polyol component of which is a mixture of oligoesteralcohols obtained as waste products in the production of dimethylterephthalate, and is modified with phosphorus or phosphorus plus chlorine‐containing antipyrenes. It is demonstrated that the introduction of antipyrenes into the foam–polyurethanes substantially enhances the combustion resistance of the composition, without impairing its physical and mechanical properties.