bluuebunny/crossref_metadata_2025_split huggingface dataset:
Degradation studies of plasticized PVC. I. Multiple internal reflection infrared spectroscopy
Authors: Hill C. A. S. 
Published: April 2003

AbstractMultiple internal reflection infrared spectroscopy (MIR) was used to study surface degradation in commercial and laboratory prepared plasticized PVC samples. Samples were subjected to accelerated (UV exposure) and natural weathering. Ultraviolet‐exposed samples show peak formation at 3200 cm−1 (OH), and 1400cm−1(CH bend), as well as increased absorption at 1720 cm−1 (CO). Outdoor‐exposed samples show essentially similar changes, but the variation in peak ratio shows large variations of a random nature; it has been proposed that rainfall has a major influence on surface plasticizer concentration.
Determination of the structural configuration of cresol–novolak resins by 13C NMR spectroscopy
Authors: Carothers J. A. , Gipstein E. , Fleming W. W. , Tompkins T. 
Published: April 2003

Abstract13C NMR spectroscopy was used to investigate the structures of a series of pure isomeric cresylic novolak resins. Chemical shifts were measured and assigned, and end groups were distinguished from the central repeat units of the chains. Based on these measurements, the number average molecular weight of the para‐cresylic oligomer was determined. A comparison of the 13C decoupled and coupled spectra of the three isomeric resins indicates that the para isomer has a linear, ordered structure in which the aromatic rings are linked only by ortho–ortho′ methylene‐bridging groups. The structures of the ortho and meta isomers are more complex and contain ortho–ortho′, ortho–para′, and para–para′ methylene bridges.
Cotton cellulose: Enzyme adsorption and enzymatic hydrolysis
Authors: Beltrame P. L. , Carniti P. , Focher B. , Marzetti A. , Cattaneo M. 
Published: April 2003

AbstractAdsorption of a crude cellulase complex from Trichoderma viride on variously pretreated cotton celluloses has been studied in the framework of the Langmuir approach, in the temperature range 2–8°C. The saturation amount of adsorbed enzyme has been related to their susceptibility to hydrolysis. In every case the adsorption process was found to be faster by 2–3 orders of magnitude than the hydrolysis step to give end products. For one substrate, the Langmuir parameters were found to be fairly well correlated with the value of the Michaelis constant Km, measured for its enzymatic hydrolysis, and the adsorptive complex (ES)ad was indistinguishable from the complex (ES) of the Michaelis–Menten model for the hydrolysis.
Crosslinking of unsaturated polyester resins by combinations of vinyl esters and methacrylates
Authors: Froehling Peter E. 
Published: April 2003

AbstractThe replacement of styrene by other crosslinking monomers in unsaturated polyester resins has been investigated because of the possible toxicity of this monomer and the strong smoke evolution of burning polyester materials. A theoretical study has been carried out to provide criteria for the applicability of classes of monomers in polyester curing. From this study it appeared that vinyl esters, vinyl ethers, N‐vinyl lactams, and styrenes are suitable, whereas acrylic and methacrylic esters and allylic or olefinic compounds are not. Combinations of vinyl esters and (meth)acrylic esters of polyols should generate IPN‐like structures. Polyesters cured by this combination of monomers gave materials with increased stiffness and strength relative to those obtained with the separate monomers and on the same level as styrene‐cured polyesters.
An analysis of transients in primary nucleation
Authors: McHugh A. J. 
Published: April 2003

AbstractAn analysis is presented of the equations governing time dependent primary nucleation in polymer crystallization. Solution of the one‐dimensional diffusion equation for the transient formation of embryos consisting of either chain folded or bundlelike nuclei, near the critical point, leads to a simple expression for estimating the transient time constant. Numerical estimates demonstrate that transient processes are unimportant in solution crystallization and potentially important in melt crystallization unless heterogeneities are present.
Graft copolymerization of methyl methacrylate onto poly(ethylene terephthalate) fibers using thallium(III) ions as initiator
Authors: Misra Sivananda , Nayak Padma L. , Sahu Gangadhar 
Published: April 2003

AbstractGraft copolymerization of methyl methacrylate onto poly(ethylene terephthalate) fibers was investigated in aqueous perchloric acid medium using thallium(III) ions as initiator. The rate of grafting was evaluated varying the concentrations of monomer, initiator, and acid and the temperature. The rate of grafting was found to increase with increase in monomer and initiator concentrations. The graft yield was found to increase with increase in the acid concentration up to 0.49 mL−1, and beyond this concentration it was found to decrease. Increase in temperature resulted in increase in graft yield. From the Arrhenius plot the overall activation energy was found to be 3.76 kcal/mol. The effect of additives such as swelling agents, inorganic salts, different solvents, and inhibitors on graft yield was studied. A suitable kinetic scheme is proposed and a rate equation derived.
Surface‐modified kevlar fiber‐reinforced polyethylene and ionomer
Authors: Takayanagi Motowo , Kajiyama Tisato , Katayose Teruo 
Published: April 2003

AbstractThe surface of poly(p‐phenylene terephthalamide) (PPTA) fiber was modified by the polymer reaction via the metalation reaction in demethyl sulfoxide to provide the fiber surface with several functional groups such as the n‐octadecyl group, carboxymethyl group, and acrylonitrile. The discontinuous fibers thus modified could be isotropically dispersed in polyethylene and ionomer. The composite of ionomer and random‐in‐plane oriented discontinuous PPTA fibers with the surface modified by carboxymethyl groups was remarkably improved in its mechanical properties, and the fiber efficiency factors of about 0.4 for both strength and modulus are comparable to the values in the composite of unidirectionally oriented discontinuous PPTA fibers and ionomer. The heat resistance of ionomer was also greatly improved by the presence of this surface modified PPTA fibers, even with volume fractions as low as 2.2%.
Pesticide encapsulation using a starch–borate complex as wall material
Authors: Trimnell D. , Shasha B. S. , Wing R. E. , Otey F. H. 
Published: April 2003

AbstractA new technique has been developed for encapsulating pesticides for controlled release. The method consists in mixing starch, pesticide, and water; adding alkali to gelatinize the starch; and treating the mixture with boric acid. The solid product is a starch–borate adduct, entrapping the pesticide within small cells. Initially, the adduct is a rubbery gel which, when treated with alcohol or ground with additional pearl starch, yields particles suitable for drying to the 10–35‐mesh range. When the starch is used to break up the gel, the technique is useful for retaining water‐soluble compounds. Water‐insoluble pesticides, emulsifiable concentrates, and wettable powders are encapsulated and recovered in high yields. Acid‐labile pesticides such as diazinon are stable in the borate gel. The process was scaled up successfully by use of a double planetary mixer.
Effect of large dosage irradiation in vacuo on polyethylene
Authors: Fujimura Takashi , Hayakawa Naohiro , Kuriyama Isamu 
Published: April 2003

AbstractThe effect of large dosage irradiation in vacuo on polyethylene was investigated by the method of double irradiation. Polyethylene was first irradiated with γ‐rays to a dosage of several hundred Mrad in vacuo at 298°K. The formed radicals were destoryed, and the polymer, changed chemically and morphologically, was irradiated again in vacuo at 77°K with a dose of 12.7 Mrad. The thermal decay of radicals produced in polyethylene by the second irradiation was investigated. The results show that many double bonds are formed in the sample irradiated to several hundred Mrad on the first irradiation. Alkyl radicals produced by the second irradiation react with these double bonds yielded by the first irradiation to form a large number of allyl radicals. These allyl radicals are much more stable than alkyl radicals radicals in vacuo at 298°K. In a sample not exposed to the first irradiation, almost all radicals formed by the second irradiation decay to form stable products. Crosslinks formed by a large amount of irradiation make the polyethylene matrix more rigid. This rigidity slows down the radical decay. These results suggest that the rate of radical accumulation in polyethylene irradiated in vacuo increases as the dosage increases.
Effect of heat treatment on the dielectric relaxation of polyacrylonitrile. II. Heat treatment under vacuum and in air
Authors: Gupta A. K. , Singhal R. P. , Maiti A. K. , Agarwal V. K. 
Published: April 2003

AbstractDielectric relaxation, infrared spectra, and X‐ray diffraction data of polyacrylonitrile (PAN) heat treated at 120°C in air and under vacuum and of the untreated PAN are reported. The heat treatment resulted in (1) lowering of dielectric constant increment, dielectric dissipation factor, and increase in relaxation temperature and glass transition temperature; (2) lowering of the intensity of CN stretching band in the infrared spectra; and (3) increase in degree of order of the X‐ray diffraction results. The changes produced by heat treatment under vacuum are found greater than those produced by heat treatment in air, which suggests that the observed effect is not caused by chemical changes in the PAN molecule under heat treatment. Interpretation of these results is attempted on the basis of the difference in the degree of bound nitrille group pairs (bound through intermolecular dipole–dipole interactions) in the structure of PAN heat treated under the different conditions.
A mechanism for the consolidation of the structure of clay–latex coatings
Authors: Watanabe J. , Lepoutre P. 
Published: April 2003

AbstractAttempts have been made to follow the process of consolidation, during drying, of the structure of a paper coating based on clay and latex by the electron microscope observation, and the analysis of coatings quenched by freezing at various stages and freeze‐dried. Three phases are considered, separated by two critical concentrations. At the first critical concentration (FCC), a 3‐dimensional network is formed, and particle motion is greatly restricted. The water–air interface recedes into the surface capillaries, creating a capillary pressure that causes a shrinkage of the 3‐dimensional network until a second critical concentration (SCC) is reached at which the network is fixed and air enters the rigid structure. Latex stiffness and colloidal interactions influence the critical concentrations. The latex coalescence process has been observed to take place over a relatively narrow concentration range after the FCC and is completed at the SCC.
Pervaporation of benzene–cyclohexane mixture by poly(γ‐methyl L‐glutamate) membrane and synergetic effect of their mixture on diffusion rate
Authors: Suzuki Fumio , Onozato Kenji 
Published: April 2003

AbstractThe pervaporation of binary liquids mixture of benzene and cyclohexane was examined by use of poly(γ‐methyl L‐glutamate) (PMLG) membrane. The permeation rate–time curve for each of benzene and cyclohexane from their mixtures changed to the longer times side by increasing the cyclohexane in the mixtures. t1/2 (the time required to reach a half‐value of the steady state permeation rate) for the each component increased exponentially with increasing of cyclohexane, which has a smaller plasticizing effect on PMLG membrane than benzene, in the mixtures. The apparent diffusion coefficients, obtained from the steady state permeation and the sorption experiments, for benzene–PMLG and cyclohexane–PMLG are dependent exponentially on the sorbed amounts of benzene. This result was explained on the bases that the diffusion of cyclohexane was enhanced synergetically with benzene coexisting in the system. This effect influenced negatively the separation of the liquids mixture by pervaporation.
Graft polymerization of acrylonitrile and methyl acrylate onto hemicellulose
Authors: Fanta G. F. , Burr R. C. , Doane W. M. 
Published: April 2003

AbstractGraft polymerizations of acrylonitrile onto both a commercial larchwood hemicellulose and a purified (low lignin) wheat straw hemicellulose could be initiated by ceric ammonium nitrate. The resulting hemicellulose‐g‐polyacrylonitrile (PAN) copolymers were fractionated by extraction at room temperature with dimethylformamide and dimethylsulfoxide. Fractions were characterized by determining both the wt % PAN in each polymer fraction and the molecular weight of grafted PAN. Saponification of the PAN component of hemicellulose‐g‐PAN gave a water‐dispersible graft copolymer with good thickening properties for water systems. An absorbent polymer, similar to the starch‐based absorbents (Super Slurpers), was produced when saponified hemicellulose‐g‐PAN was isolated by methanol precipitation and then dried. Larchwood hemicellulose was also graft‐polymerized with methyl acrylate using ceric ammonium nitrate initiation, and the hemicellulose‐g‐poly(methyl acrylate) was extrusion‐processed into a tough, leathery plastic. Although ceric ammonium nitrate could be used as an initiator for graft polymerizations onto low‐lignin hemicelluloses, it was inert with crude wheat straw hemicellulose containing 11% lignin. The ferrous sulfate–hydrogen peroxide redox system was used to initiate graft polymerizations onto this high‐lignin material, and properties of the resulting hemicellulose‐g‐poly(methyl acrylate) and saponified hemicellulose‐g‐PAN graft copolymers were evaluated.
Studies of interaction in silica/styrene–butadiene copolymers
Authors: Díaz‐Barrios Antonio , Paredes Edgar 
Published: April 2003

AbstractAdsorption, bound rubber, mechanical properties, and electron microscopy determinations were carried out in silica/styrene–butadiene copolymers. These studies reveal equivalent trends with varying copolymer composition. Thus, when the copolymer is richer in styrene, adsorbance and bound rubber increase, the stress softening effect becomes more remarkable, and silica is more uniformly dispersed in the elastomeric matrix. These results indicate that polymer–filler interaction becomes stronger when the content of styrene in the elastomer is increased. This interaction does not appear to be explicitly reflected in the other mechanical properties studied.
Studies on melt spinning. VIII. Transfer function approach
Authors: Kase Susumu , Araki Masashi 
Published: April 2003

AbstractTransfer function analyses were carried out on a linearized perturbation model of melt spinning previously developed. Results are as follows. (1) Formal proof was obtained of the criterion of spinline stability stated in terms of transfer function. (2) A new concise statement of the stability criterion was obtained: the spinline is stable when the transfer function G2(s) connecting the spinline tension to the spinline velocity does not have a zero in the right‐hand half of the complex s plane. (3) Effects of various external disturbances on filament unevenness were predicted theoretically by expressing the transfer function between each disturbance input and cross‐sectional area at take‐up in the form of frequency response Bode diagrams.
Ultrasonically delaminated and coarse mica particles as reinforcements for polypropylene
Authors: Tausz Susan E. , Chaffey Charles E. 
Published: April 2003

AbstractThe effect of the size of mica platelets used, at 30% by mass, to reinforce polypropylene was studied by comparing ultrasonically delaminated mica (diameter 5μ aspect ratio about 40) with a coarser mica (150–420μ) with and without the coupling agent 3‐(triethoxysilyl)‐1‐propanamine (Union Carbide A‐1100). Reducing the particle size of the mica (treated with coupling agent) significantly increased the tensile modulus and strength but did not affect elongation at break; it gave a small improvement in Izod impact strength; the heat distortion temperature was lower and the melt flow index was increased. Dynamic mechanical evaluation (Rheovibron) was done with a series of coarse micas (>44μ, 45–150μ, 150–250μ, and one with a broad distribution around 100μ), and an ultrasonically delaminated mica made in a continuous process (>20μ), all treated with N‐(4‐vinylphenyl) methyl‐N′‐(3‐trimethoxysilylpropyl)ethylenediamine (Dow Corning Z‐6032), at 20% by mass in polypropylene. Except for the disappearance of a peak at 0°C in the loss tangent due to the glass transition, the composite with delaminated mica did not differ from pure polypropylene, melting at 175°C. Use of the coarser micas raised the melting temperature to 200°C, increased the storage modulus, and lowered the loss tangent in the case of the three fractionated samples. The results were concordant with theories of reinforcement and microheology. The hoped‐for improvement in some properties on changing to the finer mica may not have been realized because of incomplete dispersion.
The effects of run‐in on rubber friction
Authors: Cooper R. P. , Ellis Bryan 
Published: April 2003

AbstractExperimental measurement of the change in coefficient of friction with sliding distance of a carbon‐black‐reinforced rubber on either glass or Perspex surfaces increases monotonically to a constant value as required by Saibel's theory. However, this general stochastic model does not allow for a fully satisfactory physical interpretation of the effects of run‐in on rubber friction. The present measurements for rubber on a glass surface agree well with those of Roth and co‐workers reported many years ago. The observation of these effects on Perspex does not appear to have been reported previously. It is found that a material, probably stearic acid or zinc stearate, is deposited from the rubber onto a glass surface when the rubber slides on it.
Studies on synthetic polymer plates with high surface energy. III. Diethylene glycol bis(allyl carbonate)–unsaturated sulfonic acid system
Authors: Kaneko Norio , Ohtsuka Yasuji 
Published: April 2003

AbstractSynthetic polymer plates (GPs) with high surface energy were prepared by the two‐step copolymerization process previously reported, using diethylene glycol bis(allyl carbonate) (CR‐39) as M1 monomer and unsaturated sulfonates [sodium vinyl sulfonate (VS−Na+), potassium styrene sulfonate (StS−K+), and sodium 2‐sulfoethyl methacrylate (SEM−Na+)] as M2 monomer. The contact angle (θH) of water for the acid‐treated (immersed in an aqueous 0.1 N HCl solution for 2 h) GPs decreased in the order StS−K+, VS−Na+, and SEM−Na+. In the case of M2 = SEM−Na+, the θH value was about 20°. By adding NaCl in the immersion solution and changing the pH of the immersion solution, the θH values for the CR‐39–SEM−Na+ GPs were lowered to 18.9 and 13.1°, respectively. The θH values for the above GPs were smaller than those for the CR‐39–acrylic acid or the CR‐39–methacrylic acid GPs in the previous report, whereas the contact angle (θNa) of water for the former after alkali treatment (immersed in an aqueous 0.1 N NaOH solution for 2h) was larger than those for the latter. The former had durability of water wettability superior to the latter because of the difference in dissociation characteristic of the respective functional group.
Some properties and chemical structure of phenolic resins and their derivatives
Authors: Roczniak Krystyna , Biernacka Teresa , Skarżyński Maciej 
Published: April 2003

AbstractSome physical and chemical properties of novolac and resole resins are described, IR spectra are given, and average structures of the examined resins are proposed. It was supposed that the gelation kinetics depend on the ratio of the reagents and on the structure of the resin.
Deformation band studies of axially compressed poly(p‐phenylene terephthalamide) fiber
Authors: Takahashi T. , Miura M. , Sakurai K. 
Published: April 2003

AbstractDeformation mechanism of poly(p‐phenylene terephthalamide) (PPTA) fiber during axial compression was studied. PPTA fibers were embedded in resin and axialy compressed in a tensile machine. PPTA fibers were then taken out from resin at various stages of compression. Kink band formation was examined by means of polarizing microscopy, X‐ray diffraction (WAXD), electron diffraction (ED), and electron microscopy. WAXD pattern of seriously compressed PPTA fiber shows that (200) reflection spots and arcs appear on the equator and meridian respectively. On the other hand, (110) reflection spots are confined to the equator. PPTA fiber could be splitted tangentially and radially into two kinds of thin fibrillar fragments (I and II) which reveal two distinct types of kink band and ED pattern. In fragment I obtained by tangential splitting, kink bands are formed at about 55° with respect to fibril axis, whereas in fragment II obtained by radial splitting kink bands are formed perpendicular to the fibril axis. These results were confirmed by ED studies. It was assumed that slip of (200) planes containing hydrogen bonded sheets as well as intermicrofibril slip plays an important role in the deformation of PPTA fiber during axial compression.
Rheology of unsaturated polyester resins. III. Effects of filler and low‐profile additive on the thickening behavior of unsaturated polyester resin
Authors: Kwok‐Wailem  , Han Chang Dae 
Published: April 2003

AbstractAn investigation was made of the rheological behavior of unsaturated polyester resin during thickening in the presence of filler or low‐profile additive alone and, also, in the presence of both filler and low‐profile additive. For the study, two different types of filler (CaCO3 and clay) and two different types of low‐profile additive (PMMA and PVAc) were evaluated. Compared to the resin/thickener system, the resin/filler/thickener system exhibits shear‐thinning behavior as thickening progresses, and gives rise to smaller normal stress effects. On the other hand, the resin/low‐profile additive/thickener system exhibits two distinct Newtonian regimes in the viscosity‐shear stress curves and gives rise to larger normal stress effects. The viscosity behavior of the resin/filler/low‐profile additive/thickener system was found to be very similar to that of the resin/low‐profile additive/thickener system. In all cases, when the first normal stress difference was plotted against the shear stress, a correlation was obtained which was independent of thickening period. This behavior was exactly the same as for thickening polyester resin alone, as discussed in Part II of this series.
Studies of the polymerization of diallyl compounds. XXXVIII. Telomerization of diallyl aromatic dicarboxylates in the presence of carbon tetrabromide
Authors: Matsumoto Akira , Nakane Toshio , Oiwa Masayoshi 
Published: April 2003

AbstractRadical telomerization of diallyl aromatic dicarboxylates, including diallyl phthalate (DAP) and diallyl terephthalate (DAT), was investigated in detail in the presence of CBr4 as a telogen. Telomer yield could be accurately determined by a subsidiary GPC measurement in conjunction with a precipitation method. Telomerization kinetics of diallyl compound in the presence of CBr4 was discussed and the chain transfer constant CCBr4 (= ktr/kp) was estimated to be 57.9 and 53.8 for DAP and DAT, respectively, the values which correspond to those for one functional group of diallyl compound. The degree of polymerization was significantly dependent on conversion as consequences of the fast consumption of CBr4 and the occurrence of crosslinking reaction. The rate of polymerization was enhanced with the added amount of CBr4, being ascribable to the replacement of the degradative chain transfer by the chain transfer to CBr4, the latter which yields active tribromomethyl radical in lieu of less active allyl radical. Gelation was delayed with an increase in the added amount of CBr4. Preparation of telomer in high yield and its applicability are finally discussed.