bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of nonionic surfactant and heat on selected properties of nylon 6,6
Authors: Needles Howard L. , Lu Wen‐Chu , Alger Kenneth , Varma D. S.
Published: April 2003

Heat treatment of nylon 6,6 in the temperature range of 100–175°C in the presence and absence of a nonionic surfactant (Triton X‐100) had little effect on the physical properties of the nylon, although the density of the nylon increased with increasing heat treatment temperature. The moisture regain value for the treated nylons did not change substantilly, whereas the overall wettability of the heat‐treated nylon in the presence of nonionic surfactant showed a marked improvement. Both heat treatment of the nylon alone or in the presence of surfactant had a substantial effect on the uptake of three 1,4‐substituted anthraquinone dyes on the nylon and on the resultant color of the dyed nylon.
Heat transfer to molten polymer flow in tubes
Authors: Agur E. E. , Vlachopoulos J.
Published: April 2003

This article presents the results of a numerical study (finite differences) of the heat transfer problem in flowing polymer melts. The tube wall is assumed to be at a constant temperature. The rheological behavior of the melt is described by a power law temperature‐dependent model. A convective and a viscous dissipation term are included in the energy equation. Temperature profiles, bulk temperatures, and Nusselt numbers are presented for a variety of flow entry temperatures.
Dry sintering of latex particles in pigmented coatings. I. Influence on coating structure and properties
Authors: Lepoutre P. , Alince B.
Published: April 2003

When a clay–latex coating, dried below the minimum film‐forming temperature (MFT) of the latex, was subsequently heated above the MFT, its opacity and brightness were considerably enhanced. The improvement in optical properties was optimum in the latex content range of 20–40 parts per 100 parts of clay. The sintering of the latex particles, brought about by the thermal treatment, increased the average size of the microvoids to a diameter that is optimum for the scattering of light, without significantly affecting the total void content. Data on light‐scattering coefficient, porosity, gloss, brightness, and oil permeability are discussed and compared to those of conventional coatings, i.e., of coatings dried above the MFT of the latex. Similar improvements in optical properties were obtained when coalescence of the latex particles was induced by exposure to a solvent.
Improving antistatic properties of poly(methylvinylpyridine)–poly(ethylene terephthalate) graft copolymers via alkylation
Authors: El‐Shahed M. F. , Shalaby S. E. , Hebeish A.
Published: April 2003

The alkylation reaction of poly(methylvinylpyridine)–poly(ethylene terephthalate) graft copolymers with different alkylating agents using monochloroacetic acid has proved to be the best as far as degree of alkylation and enhancement in electrical conductivity caused thereby are concerned. Kinetic investigation revealed that alkylation follows a second‐order reaction, and the apparent activation energy is 15.23 cal/mole.
Resolution in column chromatography of polymer latexes. I. The light scattering behavior of polystyrene and its effect on signal resolution in HDC
Authors: Nagy D. J. , Silebi C. A. , McHugh A. J.
Published: April 2003

A method for improving signal resolution in latex particle‐size analysis by HDC is presented and discussed. Data for the extinction cross section and specific extinction coefficient for polystyrene latex standards indicate that improvements in signal resolution can be obtained for the small particle end of broad size distributions by using turbidity detection at wavelengths less than 254 nm. Data are also discussed for the imaginary refractive index of the polystyrene standards obtained from comparisons of the extinction cross section results with Mie theory calculations. HDC runs made with bimodal and continuous distributions at 254 and 220 nm wavelength detection are also discussed to illustrate the improvements in size distribution resolution which can result.
Resolution in column chromatography of polymer latexes. II. A comparison of porous and nonporous packing systems
Authors: Nagy D. J. , Silebi C. A. , McHugh A. J.
Published: April 2003

Data are presented to compare the size separation capabilities of several porous packing systems for latex particle chromatography. Material balance problems as well as nonequilibrium behavior encountered with small‐pore systems (pores less than 1 μm) lead to the conclusion that larger pore systems (diameter 2 μm or greater) are superior from an operational viewpoint. The separation mechanism for a large‐pore Fractosil system is shown to be predominantly hydrodynamic in nature with flow separation occurring in both the pores and packing interstices. The name Hydrodynamic Permeation Chromatography, or HDPC, is used to describe the process. The effects of calibration slope and band broadening on peak resolution are compared for an HDC system and the Fractosil system indicating the superior resolving power of the HDC system. Qualitative and semiquantitative considerations are made with regard to improved porous packing characteristics for an ideal HDPC system which would improve separation efficiency and resolution.
Synthesis of cationic flocculant by radiation‐induced copolymerization of methyl chloride salt of N,N‐dimethylaminoethyl methacrylate with acrylamide in aqueous solution. II. Copolymerization at higher monomer concentration
Authors: Ishigaki Isao , Fukuzaki Hironobu , Okada Toshimi , Okada Toshio , Okamoto Jiro , Machi Sueo
Published: April 2003

The radiation‐induced copolymerization of methyl chloride salt of N,N‐dimethylaminoethyl methacrylate with acrylamide was studied to prepare a polymer flocculant that can be handled as a solid. The product obtained in the presence of 5–20% water was a solid and could be ground to a powder without drying. In order to obtain a water‐soluble polymer at a higher concentration, the effect of various additives on the copolymerization was investigated and found that alcohols bearing a hydrogen atom attached to the tertiary carbon atom effectively inhibit intermolecular crosslinking to give water‐soluble polymer. It is suggested that the formation of water‐insoluble polymer is predominantly attributable to the crosslinking of polymer chains rather than to the imidation of amide groups. Copolymerization in the presence of isopropyl alcohol as inhibitor of the crosslinking was also studied and compared with that reported previously, which was carried out at a lower monomer concentration without additives.
Effect of 1.33 MeV γ radiation and 0.5 MeV electrons on the mechanical properties of graphite fiber composites
Authors: Fornes R. E. , Memory J. D. , Naranong N.
Published: April 2003

Epoxy/graphite fiber, polyimide/graphite fiber, and polysulfone/graphite fiber composites were exposed to 1.33 MeV γ irradiation and 0.5 MeV electron bombardment for varying periods of time. The effects of the irradiation treatments on the breaking stress and Young's modulus were studied by a three point bending test. Effects were small; indeed, both electron radiation up to 5000 Mrad and γ radiation up to 350 Mrad resulted in slight increases in both stress and modulus.
Determination of the hindered amine additive CGL‐144 in polypropylene by high‐performance liquid chromatography
Authors: Schabron J. F. , Bradfield D. Z.
Published: April 2003

A method was developed to determine CGL‐144 (Tinuvin 144) in polypropylene. Polypropylene pellets were dissolved in hot decalin. The solution was cooled to precipitate the polymer. A portion of the filtered extract solution was injected onto a normal‐phase high‐performance liquid chromatography (HPLC) system consisting of a μ‐Porasil stationary phase and a chloroform:ethanol:ammonia (95:5:0.05) mobile phase. The amount of CGL‐144 was determined by peak height measurement from an ultraviolet absorption detector set at 280 nm. Injections could be made every 10 min. The limit of detection for the method as described is 0.06% CGL‐144 in polypropylene. There are no known interferences with this method.
Synthesis and characterization of mica—vinyl graft copolymers
Authors: Rao K. Panduranga , Kanniappan E. P. , Jayaraman K. S. , Joseph K. Thomas , Nayudamma Y.
Published: April 2003

Graft copolymerization of methyl methacrylate (MMA) and acrylonitrile (AN) onto mica was carried out by the ceric ion method. Experiments were carried out both in the presence and absence of oxygen; oxygen has some detrimental effect in the grafting of AN onto mica. Mica—vinyl graft copolymers were characterized using infrared spectra after purifying the crude graft copolymers for the removal of the occluded homopolymers. The percent grafting, grafting efficiency and the ratio of Rg/Rh were determined. Mica—graft copolymers were saponified by treating with aqueous alkali to convert the nitrile groups to carboxyl groups with a view to utilize these groups for coupling to collagen substrates. Since in a chrome‐tanned leather there are available coordination sites due to fixed chromium, the mica—graft copolymer could get bound, thereby resulting in a well filled‐up leather.
Effect of heat treatment on dielectric relaxation of polyacrylonitrile: Reversible thermally induced structural change
Authors: Gupta A. K. , Singhal R. P. , Agarwal V. K.
Published: April 2003

The effect of heat treatment on the dielectric relaxation of polyacrylonitrile (PAN) was studied. Dielectric measurements, in the frequency range 0.1–100 kHz and temperature range 30–170°C, on PAN heat treated at two temperatures (120 and 160°C) and the untreated PAN are reported. The loss peak height, the dielectric relaxation strength, loss peak width, and the loss peak temperature were found to vary systematically with the temperature of the heat treatment. The changes in dielectric relaxation produced by heat treatment at the higher temperature (i.e., 160°C) were considerably less than those produced by heat treatment at 120°C. The results are discussed and attributed to the variation of the degree of bound nitrile groups (through their dipole–dipole interaction) with heat treatment temperature. Heat treatment of the higher temperature (160°C) results in lower degree of bound nitrile groups in the structure than heat treatment at the lower temperature (120°C).
Grafting onto wool. XIV. Graft copolymerization of vinyl monomers by use of Mn(AcAc)3 as an initiator
Authors: Misra B. N. , Sood D. S. , Sharma R. K.
Published: April 2003

Ethyl acrylate (EA), butyl acrylate (BA), and vinyl acetate (VAc) have been graft copolymerized onto Himachali wool fiber in an aqueous medium by using Mn(AcAc)3 as an initiator. Graft copolymerization was studied at 45°, 55°, 65° and 75°C for various reaction periods. Percentage of grafting and percent efficiency were determined as functions of concentration of monomer, concentation of initiator, concentration of nitric acid, time, and temperature. Several grafting experiments were carried out in the presence of various additives which included: (i) pyridine and (ii) Et3 N. EA, BA, and VAc were found to differ in reactivity towards grafting and followed the order: EA > BA > VAc.
Active transport membrane for anions. III. Effect of crown ether and tautomeric functional groups
Authors: Ogata Naoya , Sanui Kohei , Fujimura Hideo
Published: April 2003

Membranes derived from copolymers having N‐hydroxyalkyl groups were prepared, and the active transport for anions through the membranes was investigated in the presence of a crown ether which suppresses the diffusion of counter ions. The maximum of the concentrated anions in one side cell was maintained for a long time by the addition of a crown ether in the cell, and a concentration of anions up to 50% was attained. Various N‐hydroxyalkyl groups of different lengths were incorporated in copolymers with styrene, and the transport for anions was investigated in order to establish the carrier mechanism of the tautomeric functional groups. Longer‐length alkyl moieties bearing N‐hydroxyalkyl groups led to a decrease in the active transport for anions, which supports a carrier mechanism for the membranes.
Continuous measurement of dynamic tensile mechanical properties in polymer solids over a wide range of frequencies. I. An instrument with driving force of 15 kgwt and frequency range 10−3–102Hz
Authors: Yokouchi Mitsuru , Kobayashi Yasuji
Published: April 2003

Two compact apparatuses were designed and fabricated for the study of dynamic mechanical viscoelastic behavior in polymer solids over a wide range of frequencies: (1) 10−3–102 Hz with a tensile driving force of 15 kgwt, and (2) 10–104 Hz with a maximum tensile driving force of 15 kgwt. The present paper reports the details of the instrument of (1). The instrument contains a nonresonant and forced vibration system, where the rectilinear vibration is taken from the rotating shaft of the driving motor through the double eccentric crank and conrod‐slider machineries. Measurements can be conducted at any desirable frequency (10−3‐102 Hz) and displacement (0–2 mm). Subjected to longitudinal vibration, the stress and strain in the specimen are detected by a compression‐type load cell and noncontacting displacement meter, respectively. The specimen clamp was especially devised for the compression‐type load cell, which enables direct conversion from the tensile force on the specimen to the compressive force against the load cell without any medium. Another feature of the instrument is a vertical combination of vibrational driving system, specimen clamp, and load cell. These are important for the effective transmission of the driving force to the specimen and avoidance of unnecessay mechanical vibration noises. From the Lissajous' figure formed with two signals of the stress and strain, the values of dynamic tensile modulus and loss factor for polymeric materials are easily obtained.
Electron spin resonance study of γ‐irradiated nylon 6
Authors: Takigami Shoji , Matsumoto Iwao , Nakamura Yoshio
Published: April 2003

The free radicals trapped in oriented nylon 6 filaments after γ‐irradiation under vacuum at room temperature were studied by ESR spectroscopy. The ESR spectrum measured after irradiation gradually changed to a broad singlet spectrum with decrease in the intensity. The ESR spectrum consisted of radicals with different orientation effects with respect to the outer magnetic field, and saturation effects in reference to microwave power. The simulation of the ESR spectrum from a Gaussian function gave a better fit to the observed spectrum than the calculation from a Lorentzian function. From the resolution of the spectrum from a Gaussian function, the observed spectrum is generated from three kinds of radicals:
magnified image
The relative radical concentration for the first, second, and third radical is about 75%, 6%, and 19% of the total radical concentration, respectively. With regard to the stability of the radicals, the third radical shows a comparatively long lifetime. The first and second radicals show almost identical lifetime, and their concentrations reduce to about 40% of the initial value during the 2 days at room temperature.
Preparation and reactions of epoxy‐modified polyethylene
Authors: Gallucci Robert R. , Going Rose C.
Published: April 2003

Epoxy‐modified polyolefins have been prepared by the radical grafting of glycidyl methacrylate to polymer melts. The reactions of these materials with amines and carboxylic acids were investigated. The modified polymers undergo typical epoxide reactions.
Calculation of dielectric loss of gamma relaxation process in polyethylene at low temperature
Authors: Sato Yukihiko
Published: April 2003

A method has been investigated to obtain the absorption intensity of the dielectric γ relaxation process in polyethylene by calculation. A correlation factor for evaluation of the effective dipole moment of polar groups in solid polyethylene is introduced on the assumption that with expanding distribution of relaxation time and/or increasing temperature, the extent of the canceled dipole moment due to the orientation motions of the polar groups under an alternating electric field will increase. Comparison of the calculated dielectric loss tangent with the observed one supports the assumption.
Some structure‐property relationships in polymer flammability: Studies of phenolic‐derived polymers
Authors: Zaks Y. , Lo Jeelen , Raucher D. , Pearce E. M.
Published: April 2003

The investigation of the thermal degradation of the char‐formaing phenol–formaldehyde resins is conducted to provide information for the systematic design of high temperature flame‐resistant phenolics. Three different processes of curing are used: (1) Formaldehyde or s‐trioxane is reacted with m‐substituted phenol–formaldehyde oligomers under acidic conditions to give the methylene bridged‐novolac resins. (2) Phenol and m‐substituted phenols are reacted with CH2O under basic conditions and then heated to give the methylene bridged resol resins. (3) p‐Terephthaloyl chloride and m‐and p‐substituted novolac oligomers are reacted to give cured resins with ester linkages. The evaluation of the effect of various substituents indicates that the oxygen index (OI) increases from about 33 for unsubstituted phenolics to about 75 for meta‐halogen substituted phenolics. The evaluation of the effect of various crosslinking agents shows that the OI for CH2O‐cured phenolics is 75 as compared to 50 for the trioxane cured phenolics and to 40 for the terephthaloyl chloride cured phenolics. A set of phenolic copolymers with different weight percentage content of halogen substituted phenols are synthesized as novolacs and resols. The results surprisingly indicate no increase of OI for the cured novolac copolymers, whereas the increase is observed for the cured resol copolymers. The activation energy for the thermooxidative degradation of the cured novolacs is about 12–15 kJ/mol lower as compared to that of the curd resols.
The use of extensional rheometry to establish operating parameters for stretching processes
Authors: Pearson Glen H. , Connelly Richard W.
Published: April 2003

This work describes a method of determining the limits of uniform extensibility, in terms of failure and fracture, from rheological tests in extensional flow. The limit of uniform stretching can be expressed in terms of the Weissenberg number for the process, as demonstrated by data for three chemically diverse polymers, polystyrene, poly(methyl methacrylate), and a polyester. The BKZ‐K model can be used to predict necking failure, as determined by the Considére criterion, and an empirical correlation can be derived for fracture.
Water‐swelling behavior of an ethylene–vinyl alcohol copolymer in the presence of sorbed sodium chloride
Authors: Apicella A. , Hopfenberg H. B.
Published: April 2003

The swelling behavior of water in a poly(ethylene–vinyl alcohol) copolymer (70 mol % vinyl alcohol) has been characterized at 25°C by vapor and liquid sorption experiments over a range of water activities. The activity of the vapor phase has been varied by incrementing the pressure of the water vapor in the sorption cell. Alternatively, for the liquid phase experiments, aqueous sodium chloride solutions of different concentrations have been used to vary systematically the activity of the water in the salt solution and to introduce various concentrations of salt into the copolymer films. Relaxation‐controlled sorption and Fickian diffusion have been observed as limiting cases of the water sorption behavior at high and low water activities, respectively. The effects of sorbed sodium chloride on water vapor sorption kinetics and equilibria were determined independently. A second salt phase forms within the previously homogeneous and seemingly single phase polymeric system, upon contacting the salt‐loaded film with a water vapor activity above a threshold value corresponding to the activity of water in the salt solution used to introduce the salt into the films. The water and salt solubilities in the ethylene–vinyl alcohol copolymer have been measured systematically to describe the complex sorption equilibria associated with this three‐component, multiphase system.
Polymerization of allyl methacrylate with wool fabric using different initiators
Authors: Abdel‐Hay F. I. , Khalil M. I. , Hebeish A.
Published: April 2003

Polymerization of allyl methacrylate (AMA) with wool fabrics using different initiators, namely, potassium persulphate, Fe2+H2O2, benzoyl peroxide, ceric ammonium nitrate, and vanadium pentanitrate, was investigated. The percent of polymer add‐on depends upon the type and concentration of the initiator. Addition of metallic salts such as Fe3+ to the polymerization system enhances polymerization significantly when benzoyl peroxide and potassium persulphate are used independently as initiator. The opposite holds true for ceric ammonium nitrate and vanadium pentanitrate. With Fe2+H2O2, on the other hand, the enhancement is marginal. Also studied was the incorporation of Li+, Cu++, and Fe3+ at different concentrations in AMA—wool–benzoyl peroxide polymerization systems. Determination of the polymer add‐on on the basis of double bond analysis revealed that the remained double bond is governed by the magnitude of the polymer add‐on as well as by the type of initiator.
Directional permeability of asymmetrically oxidized poly(L‐methionine) film to oxygen dissolved in water
Authors: Aiba Sei‐Ichi , Minoura Norihiko , Fujiwara Yukihiko
Published: April 2003

The permeability of an asymmetrically oxidized poly(L‐methionine) film to oxygen dissolved in water was examined. It was recognized that the permeability along an increasing gradient of oxidized methionine composition is higher than the gradient is reversed. A qualitative analysis of this result was presented in terms of the oxygen solubilities into the film and water absorbed in the film.
Aminimide as hardener/curing promotor for one part epoxy resin composition
Authors: Niino Hideki , Noguchi Saburo , Nakano Yoshitomo , Tazuke Shigeo
Published: April 2003

Three kinds of aminimide compounds were examined as latent hardeners/promotors for epoxy resins. Since aminimides are thermolyzed to generate tertiary amine and isocyanate, the compounds are useful as polymerization initiators for the epoxy group as well as promotors for epoxy–acid anhydride reaction. The pot life was over 30 days at 40°C for a formulated one‐part epoxy resin system. In comparison with epoxy resins cured with conventional hardeners, several interesting characteristics of the mechanical and electrical properties were observed. In particular, the epoxy resins cured by aminimides exhibited high tensile strength and high impact strength, which make them excellent curing agents for adhesive applications. The reasons for these unique properties are discussed.
Graft copolymerization of methyl methacrylate onto wool by use of ferrous ion–peroxodiphosphate
Authors: Subhan Jahanara , Saccubai S.
Published: April 2003

Polymethyl methacrylate has been graft copolymerized onto wool using a ferrous ion–peroxodiphosphate initiator system in an aqueous methanol medium. Graft copolymerization was carried out at 20°C, 30°C, 40°C, and 50°C. The rate of grafting was found to be dependent on the concentrations of monomer (MMA), ferrous ion (Fe2+), peroxodisphosphate (PP), wool (w), and reaction temperature. [Acid], solvent composition and ionic strenghth were also varied to study their effect on grafting. Based on the experimental results, a suitable kinetic scheme was proposed. Rate and thermodynamic parameters were also varied to study their effect on grafting. Based on the experimental results, a suitable kinetic scheme was proposed. Rate and thermodynamic parameters were also evaluated.
The rejection of polar organic solutes in aqueous solution by an interpolymer anionic composite reverse osmosis membrane
Authors: Koyama Kiyoshi , Nishi Takao , Hashida Isao , Nishimura Masato
Published: April 2003

Reverse osmosis separation for many kinds of polar organic solutes (alcohols, phenols, monocarboxylic acids, amines, and ketones) was examined by an anionic charged composite membrane. The solute permeation was carried out in single‐solute aqueous solution (200 mg/L) under applied pressure of 7.88 MPa at 25°C. The correlation between the solute rejection and polar parameters for these organic solutes have been investigated. For n‐alkyl alcohols, monocarboxylic acids, and ketones, the solute rejection increases with molecular weight and/or molecular branching. For undissociable polar organic solutes such as alcohols and ketones, solute rejections are closely related with the Taft's number. For dissociable polar organic solutes, solute rejections depend greatly upon the dissociation constant and the degree of dissociation of solute. This membrane showed higher rejection (80%) for phenol in an undissociated state at a 98% rejection level of NaCl. Also, rejections of phenolic derivatives depend upon the pH value of the feed solution and the polar effect of substituted groups. For acetic acid and methylamine, the solute rejection increases proportionally to the degree of dissociation of solute. From these facts, the main factors in reverse‐osmosis separation by an anionic composite membrane are discussed.
The rate of plasticizer uptake by suspension PVC
Authors: Davidson John A.
Published: April 2003

A microscopic technique employing image analysis was developed to measure the rate of swell of suspension PVC particles in both excess and finite amounts of plasticizer at temperatures below the crystalline melting point. The rates of plasticizer uptake derived from these swell measurements were found to be dependent upon the concentration of plasticizer and the rate of heating. A high value for the activation energy for plasticizer uptake was observed (60–100 kcal/mol) in agreement with earlier work. Each resin was also characterized by a total capacity for plasticizer (TC) which was found to be dependent on the resin type, the plasticizer type, and the maximum temperature achieved. An expression was derived for the rate of plasticizer uptake in a Brabender powder mix experiment. In this case the dry time is controlled by a single rate up to the maximum capacity for plasticizer of the resin (Gmax). Values of Gmax and TC were found to correlate on a one‐to‐one basis when measured at the same temperature. In all the cases investigated the rate of plasticizer uptake in the Brabender was found to correspond to a rate derived from image analysis swell at a plasticizer level of 0.25 cc/g. This behavior was in apparent contradiction to the concentration dependence generally observed and was demonstrated to be due to the large thermal gradients which exist in the Brabender powder mix head during the experiment. This work illustrates that Brabender powder mix times may have no relationship to dry times in a high speed mixer where heating is both even and higher temperatures are achieved.
Modelling of condensation polymerization of novolac‐type phenol–formaldehyde in homogeneous, continuous‐flow, stirred‐tank reactors
Authors: Kumar Anil , Phukan Uzzal K. , Gupta Santosh K.
Published: April 2003

A detailed kinetic model for the novolac‐type phenol–formaldehyde polymerization has been proposed in terms of five reactive sites. These sites have been shown to have different reactivities. Mass‐balance equations for homogeneous, continuous‐flow, stirred tank reactors (HCSTR) for each of the species have been written, and these have been solved numerically. A comparison of the results with those for the batch reactor shows that, for a given residence time, smaller but more polydispersed and branched chains are formed.
Alternating copolymers of butadiene and propylene: Properties and characterization
Authors: Wieder W. , Kroemer H. , Witte J.
Published: April 2003

Alternating copolymers of butadiene and propylene (BPR) made by a solution polymerization technique with a modified catalyst of the Furukawa type have highly regular structures. The constitutional repeating unit consists of one propylene and one 1,4‐trans‐butadiene unit. No chain imperfections were detected, except for ≦2% 1,4‐cis‐butadiene units. The configurations of the chiral tertiary carbon atoms in the propylene units could not be directly determined by spectroscopic methods. The intrinsic viscosities of the samples studied lie between 1.1 and 1.8 dL/g. The high molecular weight fractions (M > 2 × 105) show long‐chain branching. Crystallization effects, namely, a decrease in specific volume with time, and melting are observed after annealing unoriented samples at temperatures between −30 and −50°C. X‐ray diffraction shows that the structure of the ordered phase depends on polymerization conditions, varying between a liquid crystal‐like close packing of parallel chain segments and imperfect crystalline, three‐dimensionally periodic arrangements of chains. Both in the noncrystalline and crystalline ordered phases, the molecules are arranged in layers with a spacing of 0.47 nm. The crystalline chains have nonplanar and not fully extended conformations with a repeat distance of 0.72 nm. The rate of crystallization and the relative decrease in volume (≦1.3%) are small compared to stereoregular polymers like natural rubber and high‐cis polybutadiene. In crosslinked specimens, stretched 1:6 to 1:10, the crystalline or liquid crystal‐like structure persists up to +60°C. The imperfect nature of the crystallization of BPR is caused by stereoisomerism of the chiral carbon atoms. The chains are probably composed of short tactic sequences separated by tactic arrangements.
Graftability of beaten pulps and acetylated pulps
Authors: Heikal Salwa O. , El‐Shinnaway Nabila A. , Elkalyoubi Samera F.
Published: April 2003

Ce(IV)‐induced polymerization of acrylonitrile with acetylated bagasse and wood pulps, having different acetyl contents, has been investigated. The graft yield is dependent on the acetyl content as well as the origin of the pulp. Increasing the acetyl content of pulps caused a significant decrease in the polymer loading. However, the rate of polymerization of acetylated wood pulp is much higher than that of acetylated bagasse pulp. The ceric consumption during grafting decreases as the acetyl content of the pulp increases. The effect of beating of the pulps, to various degrees of freeness, on their reactivity toward grafting process has also been studied. Generally, the state of cellulose, as defined by its degree of beating, and the origin of the pulp strongly influenced the graft yield. In creasing the beating degree of bagasse pulp resulted in a decrease in graft yield, while beating of wood pulp, to a definite degree, inhibits the polymerization reaction. The consumption of Ce(IV) by the beaten pulps during oxidation is somewhat greater than that consumed by the unbeaten pulps, whereas the consumption during grafting of acrylonitrile onto beaten pulps depends on the initial concentration of ceric solution. Also, the effect of grafting of acrylonitrile onto acetylated wood and bagasse pulps on their strength properties as well as the effect of grafting onto beaten pulps on their properties has been investigated. Grafting of acrylonitrile onto acetylated bagasse pulp decreased its strength properties, but improved its beatability comparatively to those of original pulp (0 acetyl content). On the other hand, grafting of acrylonitrile onto acetylated wood pulp resulted in a great improvement in its strength properties compared to those of grafted unacetylated pulp. Grafted unbeaten pulps gave thinner and weaker paper than the original pulp (without grafting). Beating of bagasse pulp before grafting gave pulp which possessed a higher strength properties, at low °SR, than those of pulp beaten after grafting. Raising the °SR by rebeating the pulp after reaction up to the original value had an adverse effect on the strength. Beating of bagasse pulp before grafting did not accelerate the reaction rate, but it saved some power consumption, since the time required for beating of grafted pulp to a given °SR was lower than that of ungrafted pulp.
Synthesis and physicochemical studies of some new amphoteric ion exchangers
Authors: Kapadia R. N. , Dalal A. K.
Published: April 2003

Some new amphoteric ion exchangers have been synthesized by condensing salicylic acid, p‐hydroxybenzoic acid, sulfosalicylic acid, gallic acid, 3‐hydroxy‐2‐naphthoic acid, β‐resorcylic acid, and resacetophenone with epichlorohydrin employing ethylenediamine as a crosslinking agent. Some of the physicochemical properties, such as moisture content, true density, apparent density, void volume fraction, concentration of ionogenic groups, exchange capacity, rate of exchange, pH‐titration curves, pK values, isoionic point, thermal stability, oxidation resistance, and swelling behavior in different solvents, have been investigated.
Studies on synthetic‐polymer plates with high surface energy. V. Diethylene glycol bis(allyl carbonate)–acrylic acid copolymer plate by vapor‐phase transfer process
Authors: Kaneko Norio , Takahashi Akira , Ohtsuka Yasuji
Published: April 2003

Synthetic‐polymer plates with carboxyl group on their surface were prepared by a two‐step copolymerization process transferring M2 monomer via vapor phase. Diethylene glycol bis(allyl carbonate) (CR‐39) was used as M1 monomer, and acrylic acid was acid was used as M2 monomer. The relations between the experimental conditions and the surface properties of the resulting plates were examined in the following terms: (1) composition of CR‐39 prepolymer gel plate used and (2) concentration of benzoyl peroxide as the initiator. The plates had good water wettability and an excellent antifogging property.
The effects of oxygen diffusion on the surface photooxidation of polystyrene
Authors: Ito Masayoshi , Porter Roger S.
Published: April 2003

This paper further illustrates the applicability of multiple internal reflectance infrared spectroscopy to the analysis of near‐surface photooxidation. The results are compared with transmission infrared spectra to evaluate compositional gradients resulting from photooxidation and the influence of oxygen diffusion. The sample was a solvent‐cast film of atactic, narrow distribution polystyrene, Mw of 100,000, that had been drawn to a ratio of 3.0 at 110°C by solid state coextrusion. Irradiation of these thin films, ∼25μm thickness, was performed on exposure to air at 35°C for periods of up to 6 h using a mercury source emitting at 254 nm. On photooxidation, a board peak appears at 3200–3500 cm−1, attributable to hydroperoxide formation. The most dramatic increase in the infrared spectra is found for a carbonyl band at 1730 cm−1. It appears to result from an aromatic acid group since it is shifted to 1660 cm−1 on immersion of the oxidized polystyrene films in aqueous ammonium hydroxide. It is confirmed that the photooxidation of polystyrene occurs preferentially at the surface and that this reaction rate is greatly reduced in the drawn polystyrene film.
Chemical modification of polystyrene. II. A cation exchange resin from polystyrene electrophilically substituted with pyromellitic dianhydride
Authors: Biswas Mukul , Chatterjee Shakuntala
Published: April 2003

Crosslinked polystyrene based on condensation of polystyrene and pyromellitic dianhydride has been processed into a sulfonic acid cation exchange resin of improved thermal properties. The resin has been characterized in respect to its structure ion exchange and thermal stability by IR and elemental analysis data, total and salt‐splitting capacity measurements, pH‐titration characteristics, and TGA and DTA studies.
The influence of thermal properties on the glass transition temperature in styrene/divinylbenzene network–diluent systems
Authors: Ellis T. S. , Karasz F. E. , Brinke G. Ten
Published: April 2003

The depression of glass transition temperature in polystyrene and styrene/divinylbenzene networks, by the addition of ethylbenzene, ethyl acetate, and m‐diethylbenzene, respectively, has been investigated by differential scanning calorimetry. The predictive quality of the Couchman–Karasz treatment for the composition dependence of Tg in compatible systems was found to provide excellent agreement with experimental results for the depression of Tg by ethylbenzene, provided certain modifications were made. Qualitatively, the theory predicts that for a given diluent, the depression of Tg is particularly sensitive to the incremental change in heat capacity of the pure polymer or network. The behavior of ethylbenzene provided good quantitative agreement with the theory, provided that the incremental change in heat capacity of the diluent at its Tg was approximated by ΔCp = constant/T and that the incremental change in heat capacity of the network at Tg represents only those units capable of thermal activation. The anomalous behavior observed on plasticization by ethyl acetate and m‐diethylbenzene could in part be explained by a reduction in solvent quality or syneresis of diluent in the highly crosslinked samples.
Compatibility of some fluorosubstituted styrene polymers and copolymers in blends with poly(2,6‐dimethyl‐1,4‐phenylene oxide) and with polystyrene
Authors: Vukovic Radivoje , Karasz F. E. , Macknight W. J.
Published: April 2003

Blends of poly(p‐fluorostyrene) (PpFS), poly(o‐fluorostyrene) (PoFS), poly(styrene‐co‐p‐fluorostyrene) (SP46), poly(styrene‐co‐o‐fluorostyrene) (SO49), with poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO) and with polystyrene (PS), have been prepared by compression molding of coprecipitated polymers. Compatibility of these systems has been studied by differential scanning calorimetry. Detection of one or two glass transition regions was used to classify the blends as compatible or incompatible. Homopolymers of pFS and oFS were found to be incompatible with PPO and PS. The SP46 copolymer and SO49 copolymer were compatible with PPO in all proportions.
Selective synthesis of isobutene trimers and hexamers with oxo acid catalysts
Authors: Higashimura Toshinobu , Miyoshi Yoshihiro , Hasegawa Hiroshi
Published: April 2003

The reaction of isobutene (IB) with its dimers (IB2) catalyzed by CF3SO3H yielded isobutene trimers (IB3) in high yield in nonpolar solvents at 0°C. The initial feed of isobutene, in the presence of equimolar IB2 or more, was selectively converted into IB3 without loss or accumulation of IB2. After complete consumption of the isobutene, however, the remaining IB2 rapidly dimerized to isobutene tetramers (IB4). 13C‐NMR analysis of the products showed that the IB3 was formed via addition of the t‐butyl cation (protonated isobutene to 2,4,4‐trimethyl‐1‐pentene (an IB2 isomer); the trimer fraction was free from isomers arising from addition of the t‐butyl cation to 2,4,4‐trimethyl‐2‐pentene (another IB2 isomer) or addition of the IB2 cation to isobutene. The IB3 thus obtained was further oligomerized with CF3SO3H catalyst in nonpolar media in the range of 0 to −25°C to give a mixture of IB5, IB6, and IB7 in high yield. With EtAlCl2 as catalyst, reaction of isobutene with IB2 and oligomerization of IB3 both resulted in products with a broad molecular weight distribution containing higher oligomers and complex hydrocarbons formed via cracking of the intermediate carbocations.
Fungal degradation of polycaprolactones
Authors: Benedict Christine V. , Cook William J. , Jarrett Peter , Cameron J. A. , Huang Samuel J. , Bell James P.
Published: April 2003

Three high molecular weight polycaprolactones (M̄w= 35,000, 18,600, and 7,130) were utilized as the sole carbon source by five of six fungi tested by the American Standards for Testing and Materials (ASTM) agar plate method. The fungi wereAspergillus flavus, A. niger, A. fumigatus, Chaetomium globosum, Pencillium funiculosum, and aFusarium sp.Quantitative analysis of degradation was performed using gel permeation chromatography (GPC). GPC analysis demonstrated differences between the activities of organisms which appeared similar by the ASTM method, and showed that, while all molecular weight species within each polymer were hydrolyzed, in several cases low molecular weight end products were not assimilated. Depending on the organism, the dominant factor determining degradability was either polymer molecular weight or degree of crystallinity.
Polyphenylquinoxalines containing pendant phenylethynyl groups: Preliminary mechanical properties
Authors: Hergenrother Paul M.
Published: April 2003

Polyphenylquinoxalines (PPQ's) containing various amounts of crosslinkable pendant phenylethynyl groups were prepared from the reaction of 3,3′,4,4′‐tetraaminodiphenyl ether, 4,4′‐oxydibenzil, and 4,4′‐oxybis(4″‐phenylethynylbenzil). The distribution of the pendant phenylethynyl groups along the polymer chain was varied in an attempt to alter the properties of the polymers. Preliminary film, adhesive, and laminate properties of PPQ void of pendant crosslinkable groups and containing pendant phenylethynyl groups were determined. The thermally induced reaction of the phenylethynyl group crosslinked the polymer which resulted in better dimensional stability at elevated temperatures.
Gel permeation chromatography: The effect of flow rate on efficiency. II
Authors: Chuang Jau‐Yi , Johnson Julian F. , Cooper Anthony R.
Published: April 2003

The effect of flow rate on efficiency in gel permeation chromatoraphy has been examined over wide ranges of flow rate, i.e., linear flow velocities using columns of different diameters using both organic and inorganic packings. The results indicate a considerable increase in efficiency at flow velocities below 0.02 cm/s. No lower limit to this increase could be determined due to experimental difficulties. Between flow velocities of 0.02–0.2 cm/s little efficiency is lost.
Synthesis and properties of photosensitive rubbers. IV. Photosensitive rubbers from hydroxyethyl cinnamate and polyisoprene modified with maleic anhydride
Authors: Azuma Chiaki , Hashizume Naoko , Sanui Kohei , Ogata Naoya
Published: April 2003

Polyisoprene in o‐dichlorobenzene solution were reacted with maleic anhydride at 180°C under nitrogen atmosphere to form modified polyisoprene with α‐substituted succinic anhydride groups. These groups were converted by reaction with hydroxyethyl cinnamate in pyridine at 25°C to cinnamate groups. Various amounts of cinnamate groups as photosensitive groups could be easily introduced into polyisoprene up to 75 mol % toward polyisoprene repeating units. Polymer glass transition temperatures of the products rose linearly from −70°C for polyisoprene to 60°C with increasing amounts of the side groups. The solution viscosity of the products in chloroform decreased from 9.34 for polyisoprene to 0.77 with increasing amounts of the side groups. The photosensitivity of the polyisoprene, which is based on the photodimerization of the cinnamate groups, was higher than that of polypentenamer having cinnamate groups due to the interaction by the free carboxylic acids neighboring with the cinnamate groups. The photosensitivity of the cinnamate group was kinetically evaluated in terms of the dependence on the polymer glass transition temperature. The interaction by the free carboxylic acid groups in the polyisoprene reduced the dependence of the photosensitivity on the mobility of the polymer segments. Linear relationship between observed rate constants of the photodimerization and (TUV − Tg + 50)−1 was obtained and the slope of the line changed and became very small at higher glass transition temperatures.
Simulation of reversible AA + B′B″ polycondensations in wiped film reactors
Authors: Gupta Santosh K. , Kumar Anil , Ghosh Anup K.
Published: April 2003

Wiped‐film reactors carrying out AA + B′B″ type reversible polycondensations (where A, B′, and B” are functional groups, with B′ and B” reacting with A at different rates) have been simulated. The governing mass balance equations have been solved for two transport models of this reactor (one by Ault and Mellichamp and the other by Amon and Denson) using a combination of finite difference and the Runge–Kutta methods. The increase in the number‐average chain length μn of the polymer formed in the reactor is computed as a function of the various rate constants and the parameters characterizing the reactor. μn is found to be most sensitive to the surface area of the film and to the temperature used, both for the equal reactivity as well as for the unequal reactivity cases. For the latter, the effect of the reactivity ratio for the forward rate constants is more significant than that of the equilibrium constants. Results of the two models are also compared under similar conditions and it is found that under equivalent conditions, the Amon–Denson model gives slightly higher μn than the Ault–Mellichamp model.
The characterization of styrene–β‐pinene polymers
Authors: Sheffer Howard , Greco Gary , Paik George
Published: April 2003

Styrene was polymerized with β‐pinene at 30°C and −50°C in methylene dichloride and in m‐xylene solvents. The styrene‐to‐terpene ratio on pyrolysis suggests that the polymers made at 30°C are copolymers, whereas most of the polymers made at −50°C are not copolymers. On the other hand, ethylene, ethane, and propylene analysis suggests that more of the polymers made at −50°C are copolymers.
Wood adhesives based on lignin wastes: Influence of the carbohydrates in the polymerization of spent sulfite liquor
Authors: Calvé L. , Fréchet J. M. J.
Published: April 2003

The influence of carbohydrates on the thermosetting properties of ammonium‐spent sulfite liquor (NH4SSL) was studied using various fractions of the liquor obtained by ultrafiltration. While a low molecular weight carbohydrate‐rich fraction thermoset readily, a higher molecular weight sugar‐free fraction failed to thermoset. Optimum results in the use of NH4SSL as a binder for wood particles were obtained by adjusting the carbohydrate to lignin ratio through addition of carbohydrates to the liquor. Similarly, several sugars used alone as binders without addition of lignin gave satisfactory results at slightly higher press temperatures. A study of various sugars and similar molecules in the binding of wood particles suggested that a combination of ene‐aldehyde or ketoalcohol functionalities was likely to produce good results. Condensations involving sugars were affected by such variables as carbohydrate chain length, moisture content, acid catalysis, and press temperature.
Solid state C‐13 NMR studies of a potential crosslinking agent for aliphatic polyester–urethane block copolymers
Authors: Cholli Ashok , Koenig Jack , Sun Tong , Zhou Hanxin
Published: April 2003

Solid state C‐13 NMR was used to characterize the complex of diphenylmethane 4,4′‐diisocyanate (MDI) with acetone oxime as a potential crosslinking agent (PCA) for the aliphatic polyester–urethane block copolymers. The formation of MDI from the PCA was followed by heating the sample at 150°C. The active hydrogen atoms on the hard segments of the block copolymers can be made to react with the diisocyanate groups of the regenerated MDI from the PCA at the elevated temperature for the crosslinking. The regeneration ofNCO groups is also noted by the appearance of the 2270 cm−1 band in the FT‐IR spectrum of the heat treated PCA.
Mechanical properties of products of thermocatalytic and radiolytic styrene–acrylonitrile copolymerization
Authors: Gadalla Ahmed M. , Derini Mohamed A. E.
Published: April 2003

The mechanical properties of styrene (S)–acrylonitrile (AN) mixtures, ranging from 20 to 80 wt % S, polymerized by thermocatalytic and radiolytic techniques were studied. Maximum compressive and tensile strength was obtained for the mixture containing 60 wt % styrene. The hardness increased with styrene concentration up to 40 wt % and then remained nearly constant. Radiolytic copolymerization gave stronger copolymers than thermal copolymerization since irradiation enhances crosslinking. For the same composition, as the dose increases, the strength increases to a maximum and then decreases due to competing rates of crosslinking and degradation.