bluuebunny/crossref_metadata_2025 huggingface dataset:
Diffusion and solubility of n‐alkanes in polyolefines
Authors: Koszinowski J.
Published: April 2003

The 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.
Irradiation of cotton celluloses I and II in presence of organic solvents
Authors: Hakeem Nagwa Abdel , Abd‐El‐Nour K. N. , Moharram M. A.
Published: April 2003

The infrared spectra and dielectric properties of cotton celluloses I and II, γ‐irradiated in the presence of organic solvents have been investigated. The obtained data showed that irradiation of cotton celluloses I and II in organic solvents helps in oxidation of these celluloses and increases their dielectric constant. Examination of the infrared spectra and X‐ray diffraction (XRD) patterns revealed that irradiation of cotton celluloses I and II in organic solvents produces considerable changes in their crystallinity. It was found that the highest values of crystallinity and dielectric constant are obtained when the samples are irradiated in chloroform whereas the lowest values are obtained when the samples are irradiated in toluene.
On a blending law for two‐component blends of narrow‐distribution polystyrene components
Authors: Bersted B. H.
Published: April 2003

A 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

A 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

Effectivenesses 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

Influence 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

The 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

Quantitative 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

Polymeric 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

The 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

The 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

A 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

Effect 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

New 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

The 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

The 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

The 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

A 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

The 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

By 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

Pentachlorophenylethers (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

For 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

An 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

This 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.
An experimental examination of fracture criteria using brittle polystyrene
Authors: Gupta Surendra Kumar , Quesnel David J. , Lambropoulos John
Published: April 2003

A four‐point bend test was performed on injection‐molded bar‐shaped polystyrene specimens with notches of varying depths. The material investigated was found to be linear elastic and brittle. From the load–displacement curves, various fracture toughness parameters based on energy release rate theories and stress–intensity factors were calculated. The stress concentrations arising from the presence of finite size notches with finite root radii were also calculated. The local stress at crack initiation was found to be nearly constant for all specimens investigated while the fracture toughness parameters based on energy release rates were not constant. A distinct change in the crack propagation behavior was observed when the curvature of the stiffness vs. notch depth curve changed sign, clearly defining the onset of unstable crack growth.
Radiationresistance and thermal stability of nylon 6, acrylonitrile copolymer and polyester fabrics
Authors: Lawandy S. N. , Abd‐El‐Zaher N.
Published: April 2003

The thermal stability and radiation resistance of three polymers Nylon 6, acrylonitrile copolymer and polyester were investigated. The polymer samples were irradiated by low rate fission neutrons from a 252Cf source. The polyester showed a higher heat and radiation resistance than the two other polymers. It has to be recommended herein that polyester is the most suitable fiber for the manufacture of products in which heat buildup is produced during application, or products where radiation and heat resistance are required.
Swelling studies of perfluorinated ionomer membranes
Authors: Yeo R. S. , Cheng C.‐H.
Published: April 2003

The swelling behavior of perfluorinated ionomer membranes in various solvents were studied. It was found that the sample pretreatments and the type of the functional group have a strong effect on the swelling properties of these membranes. The swelling of sulfonate membrane is higher than that of the carboxylate membrane. Also, the membrane swelling can be increased by quenching the sample and increasing solvent temperature. Finally, the dissolution properties of this membrane are discussed.
Mechanical relaxations and moduli of isotropic and oriented linear low‐density polyethylene
Authors: Choy C. L. , Leung W. P. , Ng H. C.
Published: April 2003

The mechanical relaxations of isotropic and oriented linear low‐density polyethylene have been studied between −180 and 90°C by the use of a torsion pendulum (1 Hz), a dynamic tensile apparatus (5–90 Hz), and a longitudinal wave attenuation technique (10 MHz). The five independent elastic moduli of the oriented samples have also been measured from −60° to 50°C by an ultrasonic method. Wide‐angle X‐ray diffraction and birefringence measurements reveal that the chains in the crystalline phase are fully aligned at draw ratio λ = 4, but the degree of amorphous orientation increases steadily, indicating that the number of well‐aligned tie molecules continues to increase up to the highest attainable draw ratio (λ = 6.1). The slight depression of the γ and β relaxation peaks upon drawing results from a lowering of molecular mobility in the amorphous and interfacial regions due to the constraining effect of taut tie molecules. At low temperature, the sharp rise in the axial Young's modulus E0 and slight drop in the transverse modulus E90 with increasing λ largely reflects the overall chain orientation. Just above the β relaxation, the stiffening effect of taut tie molecules leads to increases in all moduli including the shear moduli. The two‐phase Reuss (uniform stress) model provides an adequate description of the elastic anisotropy only at λ < 3, mainly because the internal stress distribution in a highly oriented sample is not uniform but corresponds to a situation intermediate between uniform stress and uniform strain field.
Sensitivity and sensitization mechanism of halomethylated polystyrene to near UV region
Authors: Zhang Yu‐Chuan , Morita Hiroshi , Yamaoka Tsuguo
Published: April 2003

Bromo‐ and chloromethylated polystyrene (BCMS) prepared for an X‐ray resist was sensitized to near UV region by addition of some sensitizers. Among them, 2,4‐diisopentylthioxanthone (DITX) and Michler's ketone were found to be efficient sensitizers for BCMS and related polymers under irradiation with a high pressure mercury lamp. To investigate the sensitization mechanism, IR and UV spectra were measured with the BCMS/DITX system under light irradiation. From the results, together with those of oxygen and radical scavenging effects on sensitivity of the polymer, it was suggested that hydrogen abstraction of the triplet state of DITX from the polymer induces photocrosslinking between the polymer chains.
Mechanisms of antioxidant action: The role of nitroxyl radicals in the stabilization of PVC
Authors: Adeniyi J. B. , Al‐Malaika S. , Scott G.
Published: April 2003

Hindered amines and their derived oxidation products, the hindered nitroxyls and hydroxylamines are processing stabilizers and photoantioxidants for poly(vinyl chloride). The evidence suggests that oxidation of the amines occurs very rapidly and completely during mechanooxidation and that the resulting redox couple operates by a catalytic mechanism as described previously for hydrocarbon polymers.
Multiphase polymer systems: PVC/styrene copolymer alloys
Authors: Bourland Larry G. , Braunstein David M.
Published: April 2003

The compatibility of blends of poly(vinyl chloride) (PVC) and styrene copolymers containing maleic anhydride have been investigated by thermal and dynamic and mechanical studies. Unlike homopolymer polystyrene, these styrene/maleic anhydride copolymers, when blended with PVC, provide a degree of miscibility. Complete miscibility or single phase morphology is present only at low concentrations. At higher concentrations, the alloy system separates into two altered phases—neither of which is a pure component. At intermediate alloy compositions, the phases are relatively constant in polymer composition, but the ratio of phases can vary. These altered phases are dispersed at extreme concentrations and are cocontinuous at levels approaching approximately 60 wt % PVC. The intermixed, altered phases show various degrees of miscibility and provide significant adhesion between the two phases. Physical property improvements are attributable to the partial miscibility of the phases.
Control of interchange reactions of polycarbonate/polyarylate blends and their influence on physical behavior
Authors: Mondragon I. , Nazabal J.
Published: April 2003

Blends of polycarbonate of bisphenol A (PC) and a polyarylate of bisphenol A (PAr) are susceptible to showing interchange reactions in the melt state. The control of these reactions was carried out by means of the observation of the torque required to turn the Brabender and of its increase against the time due to copolymer formation in the processing equipment. Based on this variation and on glass transition temperature (Tg) measurements, the possibility of an exchange reaction in two steps in this blend was suggested. Tg measurements in melt‐ and solvent‐cast blends also showed that this mixture is immiscible at all compositions and that, by copolymer evolution, a single Tg intermediate between those of the individual constituents can be found in all compositions. The influence of immiscibility on the mechanical properties of the blends was shown by the appearance of a minimum in large‐strain properties at about 25% PAr. The behavior of the transesterified blends was very different showing a clear improvement of the tensile properties compared with those of the corresponding blends.
Semi‐1 thermoplastic interpenetrating polymer networks of physically crosslinked poly(n‐butyl acrylate) and polystyrene
Authors: Nishiyama Y. , Sperling L. H.
Published: April 2003

Poly(n‐butyl acrylate) (PnBA) chemically crosslinked with tetraethylene glycol dimethacrylate (TEGDM) and physically crosslinked PnBAs produced by neutralization of poly(n‐butyl acrylate‐stat‐acrylic acid) with NaOH or Ca(OH)2 were prepared as a polymer I network. Each polymer I was swollen with styrene and cured in situ into semi‐IPN‐TEGDM, semi‐IPN‐Na, or semi‐IPN‐Ca, respectively. Both physically crosslinked polymers maintained their shapes during the swelling procedure. Dynamic mechanical spectroscopy indicated that good mixing of the two polymers took place in the semi‐IPN‐Ca as well as in semi‐IPN‐TEGDM, but a distinct phase separation occurred in the semi‐IPN‐Na. These results were supported by their transparent or optical opaque appearances, respectively. Annealing at 180°C developed further phase separation in the semi‐IPN‐Na, but very little in the semi‐IPN‐Ca. Analyses by the incompatibility number (based on the modulus–temperature curve) and the calculation of individual phase compositions (from the glass transition temperature shifts) were used in estimating the extent of molecular mixing.
Liquid‐rubber‐modified epoxy adhesives cured with dicyandiamide. I. Preparation and characterization
Authors: Lee Yu‐Der , Wang Shi‐Kwun , Chin Wei‐Kuo
Published: April 2003

n‐Butylacrylate/acrylic acid (nBA/AA) copolymers were synthesized and used to modify epoxy resin (DGEBA) cured with dicyandiamide (DICY). The precuring reaction between nBA/AA copolymer and DGEBA, the curing cycle of DGEBA, and the effects of DICY and aluminum powder upon the adhesive strengths of modified DGEBA were studied. It was found that the optimum DICY/DGEBA ratio was 6 g/100 g, and lap shear strength and T‐peel strength increased with increasing amount of aluminum powder. The curing cycle for modified DGEBA was determined to be 1 h at 177°C.
Photo‐induced graft copolymerization: XVI: Graft copolymerization of methyl methacrylate onto nylon‐6 using isoquinoline‐sulfur dioxide and α‐picoline‐sulphur dioxide charge‐transfer complexes as photoinitiators
Authors: Lenka Subasini , Nayak Padma L. , Mohanty Indu B.
Published: April 2003

The photo‐induced graft copolymerization of methyl methacrylate onto nylon‐6 fiber was investigated using isoquinoline‐sulfur dioxide and α‐picoline‐sulfur dioxide charge‐transfer complexes as the photoinitiators. The graft copolymerization was carried out within the temperature range of 35–50°C and from the corresponding Arrhenius plot, the energy of activation has been evaluated. The effect of monomer, initiators, inhibitors, etc. on the graft yield has been investigated. The effect of solvent on the rate of grafting has also been investigated from which the chain‐transfer constant (Cs) of the solvent has been evaluated. The kinetic data and other evidence indicate that the overall polymerization takes place by a radical mechanism. The suitable mechanism has been suggested and the kinetic rate expression has been derived.
The influence of fiber pretreatment on the mechanical properties of nylon 6,6‐asbestos composites. II. Interfacial coating of asbestos fibers with a thin film of nylon 6,6
Authors: Kampouris E. M. , Papaspyrides C. D.
Published: April 2003

Nylon–asbestos composites comprise a significant proportion of reinforced nylon thermoplastics. To improve the cooperation between matrix and fibers the coating of the asbestos by interfacial in situ polymerization is proposed. Previous work on the system chrysotile‐nylon 6,6 is extended so that the reactants application order is now inversed, in order to consider any differences in the extraction resistance and the polymerization yield, in conjunction with thermal analysis studies. Experimental results gathered provide severe, but indirect, indications for the development of a strong interface bond between polymer and asbestos fibers.
Drag reduction effectiveness, shear stability and biodegradation resistance of guargum‐based graft copolymers
Authors: Deshmukh Suhas R. , Singh Ram Prakash
Published: April 2003

Guargum is a seed galactomannan and is known to be a shear stable drag reducing agent. However, the aqueous solutions of guargum are very susceptible to microbial degradation. In the present investigation, seven graft copolymers of guargum and polyacrylamide have been synthesized and their drag reduction effectiveness, shear stability, and biodegradation resistance have been determined. It has been shown that the drag reduction effectiveness and shear stability of the graft copolymer depend upon the length of the graft and number of grafts in the molecule. None of the graft copolymer solutions show any microbial degradation up to 10 days.
Thermal properties of tritylated and tosylated cellulose
Authors: Trask Brenda J. , Drake George L. , Margavio Matthew F.
Published: April 2003

Triphenylchloromethane and p‐toluenesulfonyl chloride were reacted with chopped or powdered cellulose, with and without premercerization, to form trityl–cellulose ethers or tosyl–cellulose esters. Powdered and premercerized cellulose samples were more readily derivatized. Differential scanning calorimetric (DSC) and thermogravimetric (TG) analyses were performed in nitrogen on these derivatives. DSC and TG thermograms were affected by the particular derivative and the degree of substitution. The decomposition temperatures for both derivatives were lower than for the unmodified cellulose. Trityl cleavage may have been detected by DSC as a broad endothermic area showing no weight loss that preceded the major endothermic decomposition peak. Decomposition temperatures were lowered, but not sufficiently to prevent decomposition products from being combustible. No increase in residue was effected. Thermal decomposition of tosyl–cellulose was substantially different from that of the trityl derivative. As the degree of tosyl substitution increased, decomposition occurred at lower temperatures as an increasing exotherm. Tosyl derivatives all produced high residues. These changes in thermal characteristics were indicative of increased flame resistance. Oxygen index (OI) values relate to flame resistance and show that tritylation was detrimental to the cellulose and that tosylation imparted some degree of flame resistance.
The differential permeation rate measurement of gases in PVAc
Authors: Toi K. , Izutsu M. , Mizushima A. , Ito T. , Ikemoto I.
Published: April 2003

The temperature dependence of the CO2 permeability coefficient in poly(vinyl acetate) (PVAc) was measured continuously by a differential permeation rate method. Tg was changed at upstream pressure in PVAc/CO2 system, and curious behavior of Ar was observed after CO2 conditioning. The differential permeation rate experiment successfully exhibits the effects of continuous temperature change for membranes with different histories.
Turbulent drag reduction by polymer‐fiber mixtures
Authors: Malhotra J. P. , Deshmukh S. R. , Singh R. P.
Published: April 2003

The turbulent drag reduction studies by asbestos fiber mixtures with purified guargum, purified xanthangum, and their graft copolymers have been conducted at low concentration and Re 14000 using turbulent flow rheometer designed by Hoyt. A method for making stock suspension of asbestos fibers is also suggested which gives better drag reduction. It has been found from the present studies that purified guargum–asbestos fiber mixtures give positive synergistic effect even at low concentration and synergism in drag reduction may be caused by a mixture when its constituents are rigid. A simple mixture rule equation having interaction parameter may be used for the prediction of drag reduction by the mixture.
Linear polysulfonates. I. Products of 4,4′‐(1‐cyclothexylidene) diphenol and 4,4′‐(2‐norbolidene) diphenol with some aromatic disulfonyl chlorides
Authors: Podgórski Mieczysław , Podkościelny Wawrzyniec
Published: April 2003

Aromatic (poly)cycloaliphatic polysulfonates of high molecular weight can be easily obtained by interfacial polycondensation of aromatic (poly)cycloaliphatic diphenols with aromatic disulfonyl chlorides. The polysulfonates were found to have a low degree of crystallinity, softening ranges in the region 180–310°C and molecular weights in the region: M̄n 3190–4420, and M̄w 19900–83370, thermal stability to above 300°C, and reduced viscosities in the range 0.2–1.00 dL/g.
Selective etching of thermotropic liquid crystalline polyesters
Authors: Hedmark Per G. , Jansson Jan‐Fredrik , Hult Anders , Lindberg Henrik , Gedde Ulf W.
Published: April 2003

DSC, IR, ESCA, macroscopic etching rate measurements, analysis of etchant solution, and electron microscopy conclusively show that n‐alkylamines (ethylamine, n‐propylamine, n‐butylamine, and n‐pentylamine) and NaOH selectively degrade (etch) the ethylene terephthalate (ET)‐rich phase in glassy liquid crystalline poly(p‐hydroxybenzoic acid‐co‐ethylene terephthalate) [P(HBA–ET)] with molar compositions 0.60:0.40 and 0.80:0.20. ESCA demonstrates the excellent selectivity of the n‐alkylamine etchants in the 0.60:0.40 copolymer. The 50 Å top layer of the etched samples contains 95 mol% HBA. Treatment with H2SO4 and NH3 gives ambiguous results, and these compounds are not suitable as etchants. It is demonstrated by electron microscopy on the 0.60:0.40 copolymer, in accordance with earlier reports by Joseph et al.,5–8 that the ET‐rich phase is discontinuous (1–2 μm spheres) and surrounded by an HBA‐rich matrix. SEM is a useful tool for characterization of this morphology. However, both phases have a substracture which is revealed only by TEM. The morphology of the 0.80:0.20 copolymer is fine‐textured, which means that SEM is a less suitable method for the characterization of etched samples.
A mathematical model for the Ziegler‐Natta polymerization of butadiene
Authors: Honig J. A. J. , Gloor P. E. , MacGregor J. F. , Hamielec A. E.
Published: April 2003

A mathematical model which describes conversion and molecular weight development in the homogeneous polymerization of butadiene has been developed. The reaction scheme and derivation of the model equations are included. It was found that a catalyst formation efficiency must be estimated for each polymerization. The correct trends were predicted, although weight‐average molecular weight was often underestimated. The model could not fully account for the effect of water concentration.
Osmocentrifugation in density gradients: Application to polymer latex separation
Authors: Winkler‐Hechenleitner Ana A. , Costa M. Célia P. , Galembeck F.
Published: April 2003

Polymer latexes can be fractionated by size and by chemical composition through osmocentrifugation. Density gradients are formed by centrifuging Ficoll and Percoll solutions in dialysis cells; mixed polymer latex zones are layered over these gradients and centrifuged again, leading to separated latex bands from which polymer may be collected and further analyzed. Zone migration rates in the osmocentrifugation experiment are faster than in standard centrifugation tubes.
Cold drawing of polyethylene terephthalate/polyethylene films
Authors: Berger W. , Ludwig U. , Hauffe W. , Karasz F. E.
Published: April 2003

Films made from a 77/23 weight percent polyethylene terephthalate/polyethylene blend were stretched using an Instron apparatus. The structures of the samples were examined by methods which included ion beam etching and electron microscopy. The drawn samples exhibited a metallically lustrous and highly reflective surface up to a draw temperature,TR, of 70°C and a draw ratio of about 5. Under certain conditions the change in structure caused by the stretching resulted in the formation of a highly uniform fibril‐void structure. The voids are up to 3 μm in width and 160 μm in length and are formed primarily as a result of aggregation and then separation of the microfibrils of the individual polymer components.
Aqueous solution properties of poly[3‐dimethyl (methacryloyloxyethyl) ammonium propane sulfonate]
Authors: Liaw Der‐Jang , Lee Wen‐Fu , Whung Yann‐Ching , Lin Mei‐Chih
Published: April 2003

The aqueous solution properties of an ampholytic poly[3‐dimethyl (methacryloyloxyethyl) ammonium propane sulfonate] [poly(DMAPS)] are studied by measurements of cloud point determination, intrinsic viscosity, degree of binding, and ionic strength. The minimum salt concentration and intrinsic viscosity of this polyampholyte are related to the type and concentration of added salt. Both the polymeric and monomeric betaines in the presence of NaCl have the lower degree of binding, indicating that the proton ion (H+) is relatively difficult to bind the SO−3at the end of sulfobetaine. An increase in ionic strength causes the pKato decrease at the half‐neutralization point.
Relaxation and recovery measurements by the microhardness indentation technique for transparent polymeric materials
Authors: Howes V. R. , Wall P.
Published: April 2003

A simple microhardness testing technique is described that enables the identation process to be continuously observed for transparent materials Photographic recording gave measurements of the indentation area and its changes with time, both during the on‐load period and during the subsequent period following the removal of the load. To illustrate the techniques, the time‐dependent mechanical properties of poly(methyl methacrylate) (Perspex) and diallyl diglycol carbonate (CR39) have been studied. Two parameters are defined that could be useful in identifying time‐dependent deformation properties of polymeric materials. The relaxation hardness, analogous to the relaxation modulus, describes the stress–relaxation that occurs for an identation loaded material. The surfaces resistance to damage, defined as the ratio of the applied indentation load to the remaining deformation area after load removal, is useful as an abrasion or wear indicator, particularly for assessing optical deterioration. The changes in this parameter with time describe the mechanical recovery that occurs at an indentation site in the material.
Cellulose bound chlorophenols II: Preparation and characterization of phenyloxycarbonylpentanoyl celluloses dependence of substitution on chlorophenol structure
Authors: Mair Peter , Bahadir Müfit , Korte Friedhelm
Published: April 2003

New types of polymeric phenols (including the fungicide PCP) are prepared by linking phenol and different chlorophenols to cellulose via ester bonds using adipic acid as bridging molecule. Monophenylesteracid chlorides of adipic acid are prepared as intermediates. The yield of esterification of cellulose with these compounds depends in a complicated manner on size and chlorosubstitution pattern of the phenolic substituents. It is tentatively assumed that hydrogen bonding between chlorophenol and cellulose is an important factor. The polymeric PCP ester showed fungicidal activity in an agar plate test.