bluuebunny/crossref_metadata_2025_split huggingface dataset:
On a blending law for two‐component blends of narrow‐distribution polystyrene components
Authors: Bersted B. H. 
Published: April 2003

AbstractA model, which has previously been described for relating rheological behavior in highly polydisperse polymers to molecular structure, is shown to lead to a unique blending law. Unlike previously published polynomial blending laws in the open literature, no adjustable parameters or shift factors are necessary. The blending law suggested by the model is of the form

where ϕ is defined by the molecular weights of the components and the relaxation time, τ. Good agreement between predictions of this blending law and experimental results from the literature are demonstrated. This good agreement between the experimental results for blends of narrow molecular weight distribution samples and the predictions of blending law gives further credence to the previously reported relationships to describe the effects of polydis‐persity on the rheological behavior. However, because of the complexity of the blending law in terms of the relaxation spectra, it is concluded that the description in terms of molecular weight is simpler and perhaps more fundamental.
A study of the soap‐free emulsion polymerization of styrene
Authors: Chiu Wen‐Yen , Shih Chih‐Cho 
Published: April 2003

AbstractA study on the soap‐free emulsion polymerization of styrene has been accomplished in this work. The polymerization reaction was carried out in a batch reactor under isothermal condition. Potassium persulfate was used as an initiator. In our experiments, the effects of agitation speed, monomer concentration, and initiator concentration on the number and size of polymer particles, on the conversion of monomer and molecular weight of polymers were investigated. In addition, the systems in the presence of emulsifier or CaSO3 were investigated and discussed in comparison with a system free of them.
Determination of effectivenesses of 2,6‐ditertiarybutyl cathecol tri(mono‐and‐di‐nonyl‐phenyl mixtures) phosphite and their mixtures as antioxidants for CBR, by DSC
Authors: Savaşçi O. Tunç , Baysal Shattin M. 
Published: April 2003

AbstractEffectivenesses of 2,6‐ditertiarybutyl cathecol (Dnx), tri(mono‐and‐di‐nonyl mixture) phosphite (Plg), and their mixtures as antioxidants for CBR are determined. The activatior energies of oxidative degredation for CBR are calculated. An attempt is made to corrolate the results obtained from experimental studies to storage time of CBR under ambient conditions. The relevant experiments are done mainly by differential scanning calorimetry. IR spectroscopy is used for effectiveness studies near room temperatures. Quantitative determinations of antioxidants in CBR samples are carried out by UV spectroscopy. It is found that, as an antioxidant, Dnx is more effective than Plg. When their mixture is used, 60% addition of Plg to Dnx gives almost the same effectiveness. When 45% Plg is added, maximum effectiveness is achieved and Plg is synergist to Dnx. Activation energies calculated are in good agreement with the values given in the literature. To corrolate the retarded oxidation periods obtained from DSC studies to room temperatures, DSC studies at temperatures where relative effectivenesses of different antioxidants to each other do not change by temperature must be carried out.
Factors causing variations in electrical properties and hardness of silicone rubbers
Authors: Yokoyama T. , Kinjo N. , Wakashima Y. 
Published: April 2003

AbstractInfluence of preparation conditions on the electrical conductivity, dissipation factor, and hardness of silicone rubber vulcanized by the condensation reaction using dibutyltin dilaurate as catalyst was studied. Thickness of rubber specimens and amounts of catalyst added were varied. Electrical properties were measured at 20–200°C for rubber specimens heat‐treated at 200°C for 10 h under various conditions, for example, heat treated in air, but in a sealed state in order to inhibit volatilizaions of the catalyst and vaporization of by‐products, or heat treated in a dry nitrogen atmosphere, in order to avoid oxidation and hydrolysis of the catalyst. Furthermore, the catalysts and byproducts were volatilized in air from both surfaces of the specimen in order to accelerate volatilization. Degradation of silicon rubber with heat treatment was elucidated by hardness measurements and hardness dependence of the electrical conductivity of the specimens was analyzed.
Detection of secondary relaxation in polyacetal, polycarbonate and polyether–sulfone by ultrasonic and dielectric methods
Authors: Aziz A. W. , Ab‐El‐Nour K. N. 
Published: April 2003

AbstractThe ultrasonic pulse echo technique in the range of frequencies between 1 and 5.7 MHz and temperatures between 170 and 360 K is used to detect the secondary relaxations in polyacetal, polycarbonate, and polyether–sulfone. The activation energies and the relaxation frequencies were calculated and they were found to be comparable in value. The dielectric permittivity ε′ and loss factor tan δ for such polymers were also studied over a frequency range from 102 and 105 Hz and temperatures between 30 and 80°C. At higher temperatures, the polymers possess better dielectric properties.
Quantitative and qualitative IR studies of some synthesized aromatic polysulfides
Authors: Ahmed I. K. , Rashid M. A. M. , Jawad J. K. 
Published: April 2003

AbstractQuantitative and qualitative IR analysis of some synthesized aromatic homo polysulfides and copolysulfides based on 4,4‐oxydibenzenethiol (IV), 4,4‐dimercaptodiphenyl sulfide (I) and bis‐(4‐fluorophenyl) Sulfone (II) in 1‐methyl‐2‐pyrrolidone (NMP) has been done. A satisfactory agreement of experimental results with theory was observed.
Capacitive moisture sensor devices from plasma films
Authors: Inagaki N. , Oh‐Ishi K. , Suzuki K. 
Published: April 2003

AbstractPolymeric films were deposited on Al2O3 ceramic substrates by plasma deposition from trimethylsilyldimethylamine (TMSDMA) and bis(dimethylamino)methylvinylsilane (BDMAMVS), and their capacitance‐relative humidity characteristics investigated. Films doped with methylbromide showed a linear dependence of log(capacitance) with relative humidity over the range 20–90% suggesting application on a moisture sensor device. Hysterisis effects were negligible and the response time was within 1 min.
Monitoring the dynamic mechanical behavior of polymers and composites using mechanical impedance analysis (MIA)
Authors: Jang B. Z. , Zhu G. H. 
Published: April 2003

AbstractThe techniques of mechanical impedance analysis (MIA) have been evaluated in terms of its potential for use as a reliable dynamic mechanical methodology. The method involves measuring the relation between a force input (excitation) and a motion output (response) between various points on the structure. In its most common and simple form, the force input and velocity output are measured at a single point of the structure and the values of the mechanical admittance (velocity/force) are plotted as a function of frequency. Rapid measurements and analysis of the dynamic mechanical properties of polymers and composites can be obtained by using a dual‐channel FFT spectrum analyzer interfaced with a personal computer. It is demonstrated that the technique can be used to analyze polymer viscoelasticity, to study phase transformation of thermosetting resins, and to monitor cure of integrated composite structures. Also discussed are the potential advantages and limitations of the MIA technique when applied in the fields of polymer science and engineering.
Changes of spin–spin relaxation time for EPR composites during mixing process
Authors: Furuta Motonobu , Hikasa Tadashi , Kato Eiichi 
Published: April 2003

AbstractThe changes of the mobility of rubber molecules for carbon black‐filled EPR composites during mixing process in an internal mixer have been elucidated from T2 measurement using pulsed nuclear magnetic resonance (NMR). The thickness of the tightly bound region which is formed by the direct interaction with carbon black was stabilized with mixing but the restriction of the molecular mobility increased with further mixing. The amount of the loosely bound region increased considerably throughout the mixing, indicating that this region is formed by entanglement and crosslinking of the molecules. T2 of the mobile region which is a predominant part in the composites is independent of the mixing time. EPR has the thinner tightly bound shell and longer T2S compared with EPDM, showing the effect of unsaturated bond in EPDM which can become a strong bond site with carbon black.
Preparation and testing of local polyester composites based on unsaturated polyesters as binder
Authors: Nosseir Michael H. , Doss N. L. , Toufik S. Y. 
Published: April 2003

AbstractA series of polymeric composites were prepared with sand/polyester ratio 92:8%. The sand used was local one. The polymeric composites were tested for their compressive strength, exterior volume, porosity, water uptake, specific gravity, volume of open pores and bulk density. The mechanical properties of these polymeric composites were within the range required for building bricks. No significant differences were observed between the polymeric composites made of glass sand and those from untreated sand except in exterior volume and compressive strength. Medium untreated sand was found to give better results in the mechanical properties.
The redox aqueous polymerization of acrylonitrile under pressure
Authors: Mohanty Baijayantimala , Palit Sunanda K. , Biswas Mukul 
Published: April 2003

AbstractEffect of pressure (atmospheric to 20 X 106 Pa) on the K2S2O8–Na2S2O4 initiated aqueous polymerization of acrylonitrile has been studied at 25°C. The conversion and rate of the polymerization tend to rise initially with increase of pressure and fall subsequently to a limiting value. The initial rise in the rate is consistent with an increase of kp or a decrease in kt due to high pressure. The ultimate tendency of the rate to fall is possibly due to a decrease in the diffusion rate of the monomer from the aqueous phase to the growing polymer radical site. The molecular weight shows a more or less similar trend except that the fall in the molecular weight begins at a lower pressure range than the same in the rate or conversion. This is explained on the basis of enhanced monomer transfer reaction. These observed kinetic characteristics are not sensitive to the appearance of heterogeneity in the system due to insoluble polymer phase in as much as homogeneous reaction systems in DMF or DMSO essentially exhibit the same features. The rate is proportional to the square root of the product of [K2S2O8] and [Na2S2O4] and varies linearly as the first power of the monomer concentration.
Linear polythioesters. XI. Products of polycondensation of some isomeric di(mercaptomethyl)dimethylbenzenes with isophthaloyl and terephthaloyl chlorides
Authors: Podkościelny Wawrzyniec , Szubińska Stanisława 
Published: April 2003

AbstractNew polythioesters have been obtained by polycondensation of 4,5‐di(mercaptomethyl)‐1,2‐dimethylbenzene, 4,6‐di(mercaptomethyl)‐1,3‐dimethylbenzene, and 2,5‐di(mercaptomethyl)‐1,4‐dimethylbenzene with isophthaloyl and terephthaloyl chlorides. To define the optimal conditions of polycondensation, polythioester from 2,5‐di(mercaptomethyl)‐1,4‐dimethylbenzene and isopthaloyl chloride was choosen as a model system. The optimalization of the polycondensation conditions was carried out by low‐temperature and high‐temperature solution polycondensation as well as by interfacial polycondensation. To determine the optimal conditions for polycondensation the following parameters have been studied. The kind of organic solvent, concentration of reagents, temperature and time of reaction, and, in the case of interfacial polycondensation additional, the ratio of aqueous to organic phase, kind and concentration of hydrochloride acceptor, kind and concentration of catalyst and concentration of emulsifier (Mersolan) were taken into consideration. The synthesis of all described poly‐thioesters obtained by polycondensation di(mercaptomethyl)‐dimethylbenzenes with isophthaloyl and terephthaloyl chlorides was carried out under the same optimal conditions, established for the reaction 2,5‐di(mercaptomethyl)‐1,4‐dimethylbenzene with isophthaloyl chloride. The structure of polythioesters was determined from infrared, X‐ray, and elementary analysis. Some physicochemical, thermal, mechanical, and electrical properties as well as molecular weight of polythioesters have been determined.
Studies on the rheological behavior of high‐impact polystyrene prepolymerizing systems
Authors: Zhiqiang Song , Huigen Yuan , Zuren Pen 
Published: April 2003

AbstractThe rheological behavior of high‐impact polystyrene prepolymer and its two phases separated by ultracentrifugation was studied. The viscosities of prepolymer, polystyrene phase, and rubber phase were correlated with various parameters, and a quantitative relationship among these three viscosities was proposed.
Molecular orientation distribution in injection‐molded polycarbonate discs
Authors: Takeshima Mikio , Funakoshi Nobuhiro 
Published: April 2003

AbstractThe molecular orientation distribution of injection‐molded polycarbonate discs is studied using birefringence and heat‐shrinkage measurements and laser‐Raman spectroscopy. Birefringence and heat shrinkage, which result from the molecular orientation, increase as the distance from the inflow gate decreases and as cylinder temperature decreases. Molecular orientation is reduced following annealing. Laser‐Raman spectroscopy is used to measure the molecular orientation distribution along the disc cross‐section perpendicular to the radial direction of disc. The relative intensity ratio for the 635 cm−1 and 703 cm−1 peaks in the Raman spectra correlate well with the degree of molecular orientation. The disk cross‐section is found to consist of three different molecular orientation zones; a skin zone which is in contact with the mold, a core zone located at the center, and a shear zone between the skin and the core zones. Molecules in the skin zone are nonoriented while the orientation of molecules in the core zone is considerably relaxed. The shear zone consists of highly oriented molecules. The formation process of the molecular orientation distribution is discussed in relation to birefringence and heat shrinkage.
Roller drawing of polyoxymethylene
Authors: Kaito Akira , Nakayama Kazuo , Kanetsuna Hisaaki 
Published: April 2003

AbstractThe roller drawing of polyoxymethylene (POM) sheets was carried out in the temperature range of 140–157°C. The mechanical properties, the molecular orientation, and the microstructure of the roller‐drawn POM sheets were investigated by means of tensile test, dynamic viscoelasticity, wide‐angle X‐ray diffraction, small‐angle X‐ray scattering, visible dichroic spectrum, electron microscopy, and so on. The Young's modulus and the tensile strength increased with increasing draw ratio up to draw ratio, λ of 14–15. The improvement of the mechanical properties is concerned with structural changes, such as the increase in orientation function in the crystalline and amorphous regions and the formation of taut tie molecules and crystalline bridges in the intercrystallite and interfibrillar regions. In the higher draw ratio range (λ > 15), the increase in Young's modulus and tensile strength was restricted by the formation of interfibrillar microvoids.
Cyanoethylated cellulose prepared by homogeneous reaction in paraformaldehyde‐DMSO system
Authors: Morooka Toshiro , Norimoto Misato , Yamada Tadashi 
Published: April 2003

AbstractA series of cyanoethylated celluloses with various degrees of substitution was prepared by homogeneous reaction of cellulose in PF/DMSO system. Their thermal deformation properties changed regularly with the degree of cyanoethylation. By comparing highly cyanoethylated cellulose in the series with that prepared by a traditional cyanoethylation method, it was seen that they were quite different in physical properties such as thermal deformation or tensile properties. Based on the results of dynamic mechanical measurements and infrared spectroscopy, cyanoethylated cellulose prepared in PF/DMSO system was found to be a new cellulose derivative, which includes oligo‐oxymethylene groups at the position between the glucopyraneose ring and the cyanoethyl group in the side chain. The maximum DS value of this cyanoethylated cellulose was estimated to be ca. 2.5.
Diffusion and solubility of n‐alkanes in polyolefines
Authors: Koszinowski J. 
Published: April 2003

AbstractThe diffusion and partition coefficients (relative solubility constants) of n‐alkanes (from carbon nos. 12–32) have been determined by a permeation method (pouch method) for the polyolefines LDPE, HDPE, and PP–copolymer, and PP–homopolymer at room temperature. The activation energies for the diffusion are interpreted in the meaning of the rate transition theory. Correlations exist between the activation energy ΔE and the heat of vapourization ΔvHs as well as between the activation energy ΔE and the Arrhenius preexponential factors D0. These correlations are useful for the prediction of the diffusion coefficients of n‐alkanes with carbon numbers larger than 32.
Chemical modification of cotton fiber by alkali‐swelling and substitution reactions—acetylation, cyanoethylation, benzoylation, and oleoylation
Authors: Tsuji Waichiro , Nakao Tokie , Ohigashi Kyoko , Maegawa Kinuyo , Kobayashi Noriko , Shukri Satomi , Kasai Sadako , Miyanaga Kyoko 
Published: April 2003

AbstractBy impregnating cotton fiber with alkaline swelling agents and reacting with some chemical agents which can be substituted for the hydroxyl groups on cellulose molecules in the presence of alkali, highly accessible or decrystallized cotton fibers can be obtained. As the effective substitution reactions, acetylation by acetic anhydride and cyanoethylation by acrylonitrile were applied. The cotton fibers modified by these chemical treatments showed no decrease of tensile strength, and had moisture regain higher than the untreated cotton though the degrees of substitution were as high as 20–30 mol %. The resistance to heat or acid and the soil removal were improved. Dyeability for direct dye was increased, and dyeability for disperse or cationic dye was also given. Benzoylation and oleoylation were also investigated. Crease recovery of the cotton fabrics was somewhat improved and dyeability for disperse dye was given. The cotton fabrics oleoylated after decrystallizing by alkali–acrylonitrile treatment had moisture regain almost the same as the untreated cotton, while high water repellency was given.
Pentachlorophenylcellulose preparation and investigation on its applicability as a controlled release fungicide
Authors: Mair Peter , Bahadir Müfit , Korte Friedhelm 
Published: April 2003

AbstractPentachlorophenylethers (PCP‐ethers) of cellulose are prepared using cellulosetosylates as intermediates. The products release no measurable quantities of PCP into buffered solutions (pH 4, 7, and 9, resp.). However, the modified cellulose shows no fungicidal effect in agar plate tests with the usually cellulose‐metabolizing fungus, Trichoderma viride. The lack of biological activity is attributed to the stability of the cellulose pentachlorophenyl ether bond.
Polar–polar interaction between the reinforcement and matrix for kevlar fiber‐reinforced composite: Effect of using the blend of polar polymers as matrix
Authors: Kodama Minekazu , Karino Isamu 
Published: April 2003

AbstractFor the purpose of investigating the polar–polar interaction between reinforcement and matrix in polymer composite, the mechanical dispersions were studied for the composite comprised of the Kevlar fiber and poly(hydroxy ether of bisphenol A) (I), with which poly(ethylene oxide) (II) or poly(ethylene adipate) (III) was blended as a part of matrix. It is shown by analyzing the storage modulus and loss modulus vs. temperature curves that the reinforcement–matrix interaction is increased relatively to the primary transition temperature of matrix by blending II or III with I, and II is more efficient for increase of the interaction than III. The results obtained from the mechanical dispersions do not contradict those from the Fourier transform infrared spectra on the matrix‐polymer‐coated Kevlar fiber and on the mixture of matrix polymers with benzanilide, which is used as a model compound for the Kevlar fiber.
Elasticity, tear strength, and strength of adhesion of soft PVC gels
Authors: Gent A. N. , Shimizu N. 
Published: April 2003

AbstractAn experimental study is described of the tensile modulus E of elasticity, tear strength Gc, and strength Ga of adhesion to a Mylar substrate, for PVC gels prepared with a wide range of PVC concentrations and with four different plasticizers. The modulus E, measured under quasiequilibrium conditions, was found to be approximately proportional to c3, where c is the volume concentration of PVC. The tensile behavior suggests that the molecular strands comprising the undiluted elastic network are relatively short, only about 26 C atoms long. Gc under threshold conditions was found to vary with c2.25 and to be considerably larger than (about 10 X) the value expected for a molecular network of short PVC chains. This difference is attributed to yielding of crystallites before molecular rupture can take place. Adhesion of PVC gels to Mylar was relatively weak. Both the tear strength and strength of adhesion were strongly dependent upon rate of fracture propagation and temperature, in good accord with the WLF rate‐temperature equivalence for simple glass‐forming substances. Thus, the strength of PVC gels appears to be determined largely by the glass temperature of the composition, and not by the amount or type of plasticizer except insofar as they affect the glass temperature.
The heat transfer characteristics of PTFE during quasiadiabatic decompression in nitrogen gas
Authors: Briscoe B. J. , Mahgerefteh H. 
Published: April 2003

AbstractThis article describes a series of experiments which elucidate the origin of a previously reported apparent plasticization of PTFE under a high pressure N2 environment. The results indicate that, to a first order, the apparent plasticization process is associated with the heat generated following a near adiabatic compression of the pressure environment; it is not a true isothermal plasticization in the conventional sense. The processes which contribute to this phenomenon involve subtle effects which are explored in some detail. Particularly important is the surprisingly high efficiency of the compressed gaseous media as heat transfer fluxes for intrinsically poor thermal conductors such as organic polymers. Other factors include the thermal conductivity of the gas and its heat capacity. In addition, the polymer itself manifests an intrinsic increase in its thermal conductivity due to the action of the triaxial stress. The overall temperature rise due to gas compression is very large and for N2 long sustained. The work done on the polymer by simple triaxial compression is trivial in comparison; studies in liquid media confirm this to be the case. A less extensive treatment, along similar lines, is described for the decompression of gaseous media. The combined action of gas compression and decompression together with the associated thermal cycles are briefly discussed in the context of polymer processing and the behavior of PTFE compression seals.