bluuebunny/crossref_metadata_2025 huggingface dataset:
Radiation‐grafted polymers for biomaterial applications. II. The morphology and structure of 2‐hydroxyethyl methacrylate and ethyl methacrylate homopolymer grafts
Authors: Cohn Daniel , Hoffman Allan S. , Ratner Buddy D.
Published: April 2003

The 2‐hydroxyethyl methacrylate (HEMA)/ethyl methacrylate (EMA) graft copolymer system has been found to be a useful model for investigating blood/polymer interactions. Studies of the structure of both HEMA and EMA radiation‐grafted regions were conducted using extraction methods and transmission electron microscopy of selectively stained HEMA grafts. The effect of the extraction procedure on the surface topography of HEMA‐ or EMA‐grafted films was studied by means of scanning electron microscopy. The existence of internal cells in the bulk of the HEMA network was demonstrated, and their osmotic nature was investigated. As grafting proceeds, the HEMA network becomes increasingly porous. The extraction studies carried out on EMA grafted showed that with this system an increasingly dense structure is obtained as grafting proceeds.
Near infrared measurements of terminal epoxides in polymer resin systems. I. Analytical considerations
Authors: Peck M. C. Paputa , Carter R. O. , Qaderi S. B. A.
Published: April 2003

Terminal epoxides display a group specific near infrared absorption at 4532 cm−1. This combination tone is reasonably free of interferences and can be employed to measure oxirane ring concentrations for epoxy coating resin systems during synthesis and crosslinking. With the use of low signal‐to‐noise FTIR supported by computer data manipulation, chloroform solutions of five commercially available resins were analyzed for epoxide equivalent weight and correlated with results obtained by perchloric acid titrations. The near infrared technique displays linearity for epoxy concentrations of 3.6–20.7 meq/L. Similar results were obtained via a serial concentration study, indicating that the technique is not strongly affected by matrix effects.
Birefringence of a polymeric cholesteric liquid crystal measured by refractometry
Authors: Laivins G. V. , Gray D. G.
Published: April 2003

The Abbé refractometer provides a convenient way to measure the refractive indices and birefringence of polymeric liquid crystalline solutions. The cholesteric mesophase formed by (acetoxypropyl) cellulose and its solutions in dibutyl phthalate were examined at 26°C and 50°C. The measured refractive indices were dependent on the direction of shear when the polymer was applied to the refractometer plates. The initial shear‐induced nematic‐like order relaxed slowly to the equilibrium planar cholesteric structure. The refractive index for the isotropic solutions and the two refractive indices for the anisotropic solutions all varied linearly with polymer concentration, and the width of the intermediate two‐phase region was readily determined. The changes in refractive index with polymer concentration and with orientation on the refractometer plate were rationalized with a simple model of the cellulosic mesophase, and an order parameter of 0.7 was estimated. The layer birefringence calculated from optical rotatory dispersion measurements of the cholesteric reflection band intensity was in good agreement with the birefringence measurements.
Effect of triallyl cyanurate on the properties of bis‐maleimide resins
Authors: Varma Indra K. , Gupta S. P. , Varma D. S.
Published: April 2003

This paper describes the improved processibility of 4,4'‐bis‐maleimidophenyl methane (BM) chain extended by 4,4'‐diaminodiphenyl methane (DADPM) by coreaction with triallyl cyanurate (TAC). Curing of BM, chain‐extended BM, and mixture of BM and DADPM (1 : 0.3 molar ratio) in the presence of 5, 10, 15, and 20% (w/w) of TAC was followed by differential scanning calorimetry (DSC) and thermal stability of cured resins was evaluated by thermogravimetric analysis. TAC had insignificant effect on char yield (at 800°C) of BM resin. Glass‐ and graphite fabric‐reinforced composites were fabricated using chain‐extended BM containing 10% TAC and methyl ethyl ketone (MEK) as solvent. Interlaminar shear strength was found to be 7620 psi for graphite fabric laminate containing 40% resin. Good retention of mechanical properties of laminates at 220°C up to 320 h was observed.
Latex interpenetrating polymer networks based on acrylic polymers. III. Synthesis variations
Authors: Hourston D. J. , Satgurunathan R. , Varma H.
Published: April 2003

Two latex interpenetrating polymer networks, one from a supposedly compatible pair and the other from an incompatible pair of polymers, were prepared by two‐stage emulsion polymerization. The synthesis conditions in each case were varied by altering the ratio of the glassy polymer to the rubbery polymer and also by reversing the order of synthesis. Fabricated samples of these latex interpenetrating polymer networks were subjected to hardness, stress‐strain, and dynamic mechanical measurements. Hardness and stress‐strain measurements showed that, although the second formed polymer dominated the final mechanical properties, the compatibilities of the polymer pairs played an important role. Dynamic mechanical analysis for the inverse systems showed evidence of enhanced mixing.
Graft copolymerization of styrene onto ethylene‐vinyl p‐nitrobenzoate copolymer by chain transfer reaction
Authors: Nakamura Shigeo , Kasatani Hideo , Matsuzaki Kei
Published: April 2003

The effect of steric hindrance on the attack of growing polymer radicals to the reaction sites on a trunk polymer was examined in the graft copolymerization of styrene onto a trunk polymer with pendant aromatic nitro groups by chain transfer reaction of growing polymer radicals to the pendant nitro groups. The nitro groups on ethylene‐vinyl p‐nitro benzoate copolymer (EVNB) are more effectively utilized in the graft copolymerization than those on the vinyl p‐nitro benzoate homopolymer (PVNB) previously used as a trunk polymer, because the nitro groups are distributed less frequently on the trunk polymer in the former than in the latter. This was also confirmed by the higher chain transfer constant of growing polystyrene radicals to EVNB compared to that of PVNB.
Synthesis, characterization, properties, and derivatives of poly(starch‐g‐(1‐amidoethylene)). I. Synthesis and characterization
Authors: Meister John J. , Sha Mu Lan
Published: April 2003

Poly(starch‐g‐(1‐amidoethylene)) can be formed by aqueous, free radical polymerization of 2‐propenamide on lintnerized, potato starch. Initiation is by attack of cerium ions (+IV) on the D‐glucopyranosyl units of starch. The reaction produces a water‐soluble thickener with molecular properties of the product controlled, in part, by the gel effect induced in virtually all syntheses. Yield of product varies from 38 to 100% with yields of 90–100% being common. Products containing less than 50 wt % sidechain were found to be difficult to dissolve once they were recovered from the synthesis mixture. A sample with a design molecular weight of 0.8 × 106 and 4 grafts per backbone formed 3.9 wt % of a water‐insoluble solid in the reaction mixture. The solid, which had a composition similar to that of the reaction mixture, may be the result of selective reaction within the distribution of backbone molecules.
Thermal properties of rigid polymers. I. Measurement of thermal conductivity and questions concerning contact resistance
Authors: Hall J. A. , Ceckler W. H. , Thompson E. V.
Published: April 2003

Several studies of the influence of contact resistance on the measurement of thermal conductivity of polystyrene using a steady‐state device are presented. In each case it is seen that, although this influence can perhaps be minimized, it cannot be eliminated as an experimental complication. A novel technique is then described which does eliminate entirely contact resistance as a variable, and this technique is shown to yield an unequivocal value of thermal conductivity.
Calorimetric quality control of UV cured optical fiber‐coatings
Authors: Nicolais L. , Apicella A. , Grimaldi P.
Published: April 2003

The application of ultraviolet (UV)‐curable polymeric coatings provides optical fibers with improved strength, microbending resistance, and long‐term durability. To ensure constant optical properties of the glass fibers during their life, fully polymerized coatings are needed. Test methods capable of determining the degree of cure and the consistency of the polymeric materials used are therefore required by the fiber technology. This investigation deals with the description of a calorimetric test method for the direct determination of the prepolymer reactivity and its final degree of cure. The analytical technique uses a modified differential scanning calorimeter (DSC) capable of direct measurements of heat fluxes generated during the UV‐activated polymerization of photoinitiated acrylic prepolymers. Finally, the degree of cure and the glass transition temperatures were determined for the polymerized coating also in presence of sorbed moisture.
Photoprotective agents for wool. Synergism between UV absorbers and antioxidants
Authors: Carr C. M. , Leaver I. H.
Published: April 2003

Several antioxidants alone, and in combination with sulfonated UV absorbers, have been evaluated as photoprotective agents for wool. Mixtures of phenolic antioxidants and sulfonated UV absorbers of the 2‐hydroxyphenylbenzotriazole class were found to exhibit synergistic behavior; the most effective UV absorber also gave the strongest synergistic effect with the antioxidants. Of the systems studied, the hindered phenol, calcium bis ((ethyl‐(3,5‐di‐t‐butyl‐4‐hydroxybenzyl)‐phosphonate)) (Irganox 1425), when used in conjunction with a sterically hindered benzotriazolesulphonate, afforded wool the best protection against photoyellowing and phototendering in sunlight, behind window glass. Sulfonated derivatives of hindered phenols acted synergistically with UV absorbers when treated fabrics were exposed to an artificial light source, but not when fabrics were exposed to sunlight through glass.
Mercerized and cross‐linked cotton yarns I. Effect of tension during mercerization on degree of cross‐linking and distention index
Authors: Pandey S. N. , Nair Prema
Published: April 2003

A study of the effect of tension during mercerization on the distention index and distribution of cross‐link in cotton yarns cross‐linked by different processes with formaldehyde is reported. The yarns were slack mercerized and then restretched to 90–103% of their original lengths. The mercerized samples were then cross‐linked with formaldehyde by form W and form D processes. Estimation of sol‐gel, distention index (DI), and distribution of cross‐links in cotton yarn samples are discussed. The results of these analyses provide important information on the gross uniformity of the distribution of the cross‐link in the fiber structure of cotton yarn mercerized under varying tensions and cross‐linked.
The crystallization and formation of cluster of ethylene ionomer during physical aging
Authors: Kohzaki Mamoru , Tsujita Yoshiharu , Takizawa Akira , Kinoshita Takatoshi
Published: April 2003

The effect of the physical aging of ethylene ionomers was studied for the samples with the acid content of 5.4 mol%, and the degree of neutralization, 0%, 60% Na, 60% Zn, and 90% Zn. The information about the crystal and the cluster part of the physically aged ionomers was obtained by differential scanning calorimetry and by dynamic viscoelastic measurements, respectively. The degree of crystallinity and the dynamic modulus for the ionomers of the degree of neutralization 0%, 60% Na and 60% Zn increased gradually with the aging time; on the other hand, the crystallinity of 90% Zn remained constant and the modulus at 100°C increased to a certain value up to a period of 100 h, but thereafter the crystallinity increased remarkably and the modulus remained. These facts indicate that the crystallization of neutralized ethylene ionomer starts after clustering and the clustering would finish at early stage of the physical aging for intermediately neutralized ethylene ionomer. The physical aging effect of the ethylene ionomers was, thus, found to be important to material design.
Bulk functionalization of ethylene‐propylene copolymers I. Influence of temperature and processing on the reaction kinetics
Authors: Greco R. , Maglio G. , Musto P. V.
Published: April 2003

The dicumylperoxide (DCPO) promoted functionalization of an ethylene‐propylene copolymer (EPR) by means of dibutyl meleate (DBM) has been studied in bulk at constant reactant composition (100 : 10 : 1 by wt EPR‐DBM‐DCPO) in the range of temperature from 140 to 200°C. The reactants have been premixed in a Brabender‐like apparatus at 90°C in which no decomposition of the radical initiator could occur. This was done in the frame of a general discussion of polyolefin functionalization, to assure the homogeneity of the reactant mixture before the reaction occurred.

The kinetics of the reaction followed by an infrared (IR) technique was carried out according to two different procedures: a static one in a thermostatic bath and a dynamic one in the same mixer used for the premixing step. The kinetics in the two cases are very comparable, and a common activation energy of 40 kcal/mol has been measured. Some minor differences exist, however, which are very interesting from a scientific point of view.

The kinetics of EPR degradation during the reaction has been indirectly monitored by means of solution viscosimetry. The results have been compared with the reaction kinetics.

A thorough discussion of the proposed mechanism for grafting and degradation reactions has been also provided.

Further work is in progress to analyze the effect of the EPR copolymer and of reactant composition on the functionalization and degradation reactions.
Elastomeric domain‐type interpenetrating polymer networks
Authors: Silverstein M. S. , Narkis M.
Published: April 2003

Elastomeric latex interpenetrating polymer networks (IPNs) can result from a two‐stage emulsion polymerization procedure in which styrene is polymerized and cross‐linked on a lightly cross‐linked polyacrylate (PA) seed latex in a ratio of 75 : 25 PA‐PS. The multiphase nature of these IPNs is indicated by two distinct Tgs and is confirmed by cold‐stage transmission electron microscopy and by the unique mechanical and rheological properties that are intimately related to the material's structure. PS microdomains reinforce the elastomeric PA, yielding a significant modulus, and interparticle PS physical ties yield a significant ultimate tensile strength. The elastomeric latex IPN's dual thermoset‐thermoplastic nature is revealed in a stick, slip, roll flow mechanism of the cross‐linked submicrometer particles, which can be injection molded as a thermoplastic. The relationships among the polymerization procedure, the structure, and the physical properties are characterized by the examination of several different materials using a variety of analytic techniques.
Properties of cotton fibers containing the cellulose IV crystal structure
Authors: Zeronian S. Haig , Ryu Hyo‐Seon
Published: April 2003

Complete conversion of the crystal form in cotton fibers to cellulose IV (cell IV cotton) was obtained by heat treatment of ethylamine‐treated cotton cellulose in either saturated steam or formamide. Degradation of the fibers was not extensive during the conversion process; oxidative damage appeared to have been confined primarily to the accessible regions of the fibers. Examination by scanning electron microscopy indicated that the surface of the cell IV cotton was smoother than that of the same cotton with other crystal forms, namely, the starting cotton (cell I cotton), mercerized cotton (cell II cotton), and ethylamine‐treated cotton (cell III cotton). Fiber accessibility increased in the order cell I cotton < cell III cotton ≤ cell IV cotton < cell II cotton. Using leveling‐off degree of polymerization as the measure, it appeared that the lengths of the crystallites in cell I cotton were much higher than those in cell II, III, and IV cotton. The strength of cell IV cotton was comparable to that of cell I cotton even though its degree of polymerization was significantly lower. It is suggested that heat treatments in formamide have an annealing effect on cotton that results in increases of strength.
Mass spectrometric studies of sulfonyl esters of diazonaphthalenones: Relationship between fragmentation patterns and photolithographic mechanisms
Authors: Sorbier B. M. Du , Kulkarni S. , Vouros Paul , Kirby D. P.
Published: April 2003

Esters of 2‐diazonaphthalenone sulfonic acid were examined by mass spectrometry using electron impact and chemical ionization techniques. Charactristic differences in the fragmentation patterns of positional isomers have been observed. In a manner analogous to photo‐induced decompositions, the diazoketo functional groups fragment by elimination of N2 to form an indenoketene ion. An alternative process involves the apparent loss of 26 mass units from the molecular ion. The latter process is explained by evoking the abstraction of two hydrogen atoms following the loss of N2. With deuterium isotope labeling, it has been shown that the hydrogens are abstracted from the surface of the probe tip used for introduction of the samples into the mass spectrometer. It is concluded that an environment rich in hydrogen or proton‐donating properties promotes and enhances the incorporation of the hydrogen atoms and formation of the [M‐26] species at the expense of the ketene moiety, which is an important intermediate in the photoresist process. By extrapolation it may be inferred that the efficiency of the photolithographic process could be influenced by the availability of protons in the photoresist matrix.
Thioxanthone derivatives as photoinitiators in micelle photopolymerization
Authors: Fouassier Jean‐Pierre , Lougnot Daniel‐Joseph
Published: April 2003

This paper provides a complete survey of the primary processes involved in typical oil‐and water‐soluble thioxanthane derivatives dissolved in sodium dodecyl sulfate micelles, in the presence of monomers and amines. Special emphasis is laid on the determination of the rate constants of the different processes and the absorption spectra of the transients. Relevant data are shown and discussed with reference to the effectiveness of these molecules as photopolymerization initiators.
Divinylbenzene‐crosslinked terpolymer consisting of hemin, styrene, and 2‐methyl‐5‐vinylpyridine as cyanide ion exchanger. Preparation of the polymer in the form of beads by suspension polymerization
Authors: Kokufuta Etsuo , Saito Kiyoshi
Published: April 2003

Bead‐shaped, divinylbenzene‐cross‐linked terpolymers, consisting of hemin (ferri‐protoporphyrin IX chloride), styrene, and 2‐methyl‐5‐vinylpyridine, were prepared by suspension polymerization in which all or part of styrene monomer was replaced with divinylbenzene. Analogous terpolymers of the cross‐linked and uncross‐linked formless types were also prepared by solution polymerization. All the terpolymers obtained were characterized by electron spin resonanance spectroscopy, scanning electron microscopy, and measurement of specific surface area. The characteristic of the adsorption of cyanide ion onto the terpolymer beads was investigated and compared with those adsorbed onto their analogs. The column separation of cyanide ion with the terpolymer beads was carried out to examine the ion‐adsorbing capacity. It was found that the suspension polymerization is just appropriate to prepare a cyanide ion exchanger in the form of beads.
Laser pyrolysis of characterized cyanurate network polymers
Authors: Cozzens Robert F. , Walter Peter , Snow Arthur W.
Published: April 2003

A series of bisphenol A dicyanate network polymers with degree of crosslinking varied by addition of 4‐cumylphenylcyanate were prepared and characterized by model compound study, infrared spectroscopy, DSC, TGA, and statistical analysis. Laser ablation energy measurements varied from 14 to 18 kJ/g and were found to linearly increase with degree of crosslinking. Comparative ablation energy analysis was made with other aromatic, nonaromatic, linear, and crosslinked polymers.
Mechanical behavior of quenched isotactic polypropylene crystallized by thermal and solvent treatments
Authors: Candia F. De , Russo R. , Vittoria V.
Published: April 2003

Films of quenched isotactic polypropylene were either annealed at 80, 90, 100, 110°C for 30 min or kept in different liquids for 24 h at 25°C. The liquids were cyclohexane, chloroform, and carbon tetrachloride. Both treatments induce crystallization of quenched films and the development of crystallinity was detected by carrying out density and wide‐angle x‐ray scattering measurements. Small‐angle light scattering experiments, performed on the starting and on the crystallized samples, show that in the zones in which spherulites are present the basic gross morphology does not change after the treatments, although the increase of crystallinity is substantial for all the samples. The analysis of the mechanical behavior also indicates the absence of relevant morphological changes following the different treatments. On the other hand the increased crystallinity strongly influences the complex structural and molecular rearrangement characterizing the transition from the spherulitic to the fiber morphology. The results are discussed in terms of the great significance that structural modifications have on the physical properties.
Graft copolymerization of methyl methacrylate on holocellulose
Authors: Okieimen E. F. , Idehen K. I. , Ahiedu H.
Published: April 2003

Graft copolymerization of methyl methacrylate initiated by ceric ion in aqueous medium on bleached holocellulose was studied at 29°C. It was found that an increase in the concentration of ceric ion and oxidation of the holocellulose with aqueous potassium dichromate solution resulted in increased levels of incorporation of poly(methyl methacrylate) graft copolymer, but were associated with reductions in the efficiency of grafting. Thiol groups were introduced on the holocellulose by treatment with dilute thioglycollic acid solutions at 29°C. The influence on the level of grafting and on the molecular weight of the grafted polymer by the incorporated thiol groups on the substrate was examined.
New aspects in cationization of lignocellulose materials. IX. Flame retardancy effect of modification with nitrogen and sulfur containing groups
Authors: Šimkovic Ivan , Pastýr Jan , Antal Miroslav , Balog Karol , Košik Štefan , Plaček Jan
Published: April 2003

Lignocellulose materials were modified with 3‐chlor‐2‐hydroxypropyltrimethylammoniumchloride, 1,3‐bis(3‐chlor‐2‐hydroxypropyl)imidazoliumhydrogensulphate, and 2‐chlorethyl‐sodiumsulphonate and the flame‐retardant properties of materials obtained were studied. The flame‐retardant effect was proved using the limited oxygen index (LOI) method and values up to 32.8 vol % of oxygen were determined. The LOI values were higher when the modification was done without using NaOH for activation, but in that case the alkylating groups were not chemically bonded to the material. The NaOH activation was necessary to obtain material with flame‐retardant properties stable against washing. No synergistic effects were observed when the material was modified with both nitrogen‐ and sulfur‐containing groups.
Modification of cation exchange membrane by grafted poly(4‐vinyl‐N‐methylpyridinium‐iodide)
Authors: Shimasaki Kazuhiro , Ihara Hirofumi , Mizutani Yukio
Published: April 2003

It is well known that cation exchange membranes, having a very thin layer of a cationic polyelectrolyte on the membrane surface, have preferential permselectivity for monovalent cations in a monovelent‐divalent cations system. We studied the relationship between preferential permselectivity and molecular structure of the cationic polyelectrolyte. Grafted poly(4‐vinyl‐N‐methylpyridinium‐iodide) was used and was compared with poly(4‐vinyl‐N‐methylpyridiniumiodide). The backbone polymers were poly(styrene‐co‐p‐benzylstyrene) and poly(benzyl), onto which 4‐vinylpyridine was grafted by anionic polymerization and then quaternized with CH3I. The grafted poly(4‐vinyl‐N‐methylpyridinium‐iodide) is effective in making the cation exchange membrane preferentially permselevtive for Na+ ‐ Ca2+ system and is more preferable than poly(4‐vinyl‐N‐methylpyridinium‐iodide) in terms of electric resistance of the membrane. However, the relationship between the molecular structure of the cationic polyelectrolyte and the durability of the preferential permselectivity is not clear.
Determination of paper sheet fiber orientation distributions by a laser optical diffraction method
Authors: Yang C.‐F. , Crosby C. M. , Eusufzai A. R. K. , Mark R. E.
Published: April 2003

The combination of the laser and optical diffraction analysis provides a powerful tool for the determination of fiber orientation distribution in any paper sheet of basis weight low enough to be translucent to the laser beam. The coherent light beam from the laser is diffracted by the sample. It undergoes a Fourier transform from which the orientation distributions can be calculated. Measurements were made on 14 different samples of various degrees of orientation, including an essentially random handsheet as a control. The cross‐direction/machine direction elastic modulus ratios of the samples were found to correlate well with the distribution functions fitted to the orientation data. The correlation curve was S‐shaped, with a drastic drop in the modulus ration in the medium range of fiber orientation.
Benzoyl peroxide as a crosslinking agent for polyethylene
Authors: Kampouris E. M. , Andreopoulos A. G.
Published: April 2003

The efficiency of benzoyl peroxide (BPO) as a crosslinking agent for polyethylene (PE) was studied as a function of concentration and temperature in relation with the resin melt flow index and particle size. The investigation can lead to the selection of suitable materials and operating conditions for a proper crosslinking process. The decomposition characteristics of the initiator studied can be regulated in order to allow faster production rates when crosslinked PE are prepared by injection molding.
The effect of resin chemistry on the curing behavior and chemorheology of unsaturated polyester resins
Authors: Lee Dai‐Soo , Han Chang Dae
Published: April 2003

The effect of the structure of unsaturated polyester resin on its curing and rheological behavior during isothermal cure has been investigated, using three different grades of resin. In the investigation, the structure of the resins was determined, using nuclear magnetic resonance spectrometry (NMR), together with chemical analysis. Both a differential scanning calorimeter (DSC) and an infrared (IR) spectrometer were used to determine the curing kinetics, and a cone‐and‐plate rheometer was used to determine the variation of rheological properties during isothermal cure. On the basis of the experimental study, we have concluded: (1) at the same styrene‐to‐fumarate mole ratio, the resin having isophthalates cures slower than the one having none; (2) everything else being equal, the resin having a high styrene‐to‐fumarate mole ratio cures faster than the resin having a low one; (3) the higher the concentration of initiator, the faster a resin cures. It has been found that a resin that cures faster does not necessarily achieve a higher final degree of cure than one that cures slowly. We have found that a mechanistic kinetic model developed in our previous investigation is very useful for investigating the reactivity of unsaturated polyester resin, by determining the rate constant and activation energy of the propagation reaction. On the basis of rheological investigation, we have concluded that both tη∞ determined from steady shearing flow measurement and ttan δ = 1 determined from oscillatory shearing flow measurement may be used as a measure of gel time.
The influence of resin characteristics on the high speed melt spinning of isotactic polypropylene. II. On‐line studies of diameter, birefringence, and temperature profiles
Authors: Lu Fu‐Min , Spruiell Joseph E.
Published: April 2003

An investigation was carried out of the high speed melt spinning of three polypropylene resins with melt flow indices of 12, 35, and 300. On‐line measurements were made of diameter, birefringence, and temperature as a function of distance from the spinneret for a range of spinning conditions for each polymer. A plateau (decrease of cooling rate) in the temperature profile was associated with the occurrence of crystallization in the spinline. The position of this plateau correlated with a rapid rise in the birefringence profile and a rapid decrease in the rate of drawdown in the diameter profile. The temperature and birefringence profiles were used to determine the temperature and position on the spinline at which the onset of crystallization occurred. It was found that the position and temperature of crystallization onset varied considerably with changes in take‐up velocity, extrusion temperature, and resin melt index (weight average molecular weight). The crystallization onset occurred nearer the spinneret and at higher temperatures with (1) an increase of take‐up velocity, (2) a decrease of extrusion temperature, or (3) a decrease of resin melt flow index. An analysis was carried out to estimate the rate of stress development with distance along the spinline; the results were also used to estimate the stress at the onset of crystallization for each spinning condition. It was concluded that the observed behavior could be attributed to the role of spinline stress in producing molecular orientation and consequent increase of crystallization rate.
Improvement of plasma etching durability of positive working resist by copolymerization, blending, and crosslinking
Authors: Ueno Nobuo , Doi Yasunori , Sugita Kazuyuki , Sasaki Shigeru , Nagata Shiro
Published: April 2003

The plasma etching durability of O2 and CCl4 was investigated for copolymer and polymer blend of poly(methyl methacrylate) (PMMA) and poly(α‐methylstyrene) (PMSt) as a function of MSt content. Further, the effects of crosslinking on plasma etching were studied by incorporating N‐methylolated methacrylamide into the copolymer as a crosslinkable site during prebaking. The plasma‐etching resistance of PMMA was largely improved by incorporating or adding only a small amount of MSt. Especially in the case of the CCl4 plasma etching, the copolymer and the polymer blend with 10 mol% of MSt showed etching resistance as great as that of PMSt homopolymer. Stabilization of the polymers against the plasma etching can be explained by the sponge effect, the energy migration followed by the quenching by the phenyl ring. The polymer blend offered similar etching resistance as the copolymer, indicating an effective occurrence of the energy migration between the polymer chains. Etching resistance was also improved by crosslinking, also due to the enhancement of the sponge effect.
Experimental investigation of vinyl chloride polymerization at high conversion—temperature/pressure/conversion and monomer phase distribution relationships
Authors: Xie T. Y. , Hamielec A. E. , Wood P. E. , Woods D. R.
Published: April 2003

An equilibrium model relating temperature, pressure, monomer conversion and monomer phase distribution for vinyl chloride polymerization has been developed. This model can be used to determine the monomer conversion beyond the pressure drop by measurement of reactor temperature and pressure. It can also be used to estimate monomer conversion at the pressure drop point and the distribution of monomer in all the phases over the entire extent of polymerization. A series of experiments to measure the solubility of VCM in water and PVC were carried out in the temperature range 40–70°C. Correlations of the solubility of VCM in water and the VCM–PVC interaction parameter with temperature, respectively, were obtained from the experimental data.
ESCA and FT‐IR studies on boundary‐phase structure between blend polymers and polyamide substrate
Authors: Kodama Minekazu , Kuramoto Kazuo , Karino Isamu
Published: April 2003

Electron spectroscopy for chemical analysis (ESCA) and Fourier‐transform infrared (FT‐IR) attenuated total reflection (ATR) studies have been made on the film of blend polymers consisting of poly(hydroxypropyl ether) of bisphenol A (P) and poly(ethylene oxide) (E) or P and poly(ethylene adipate) (A) formed on nylon‐6 (Ny) substrate to investigate the boundary‐phase structure between the substrate and the polymer blends. For the case of P/A blend, A is enriched to the depths probed by both ESCA (below ca. 60 Å) and FT‐IR‐ATR (below ca. 0.7 μm) from the nylon‐6 surface. For the P/E blend, though P is enriched to the depth probed by ESCA from the Ny surface, the enrichment of neither of the blend components can be found to the depth probed by FT‐IR‐ATR. These results indicate the different susceptibility between P/A and P/E blends to the influence from the Ny substrate.
Protein‐reactive, molded polystyrene surfaces having applications to immunoassay formats
Authors: Chu Victor P. , Tarcha Peter J.
Published: April 2003

Injection‐molded polystyrene surfaces were chemically modified rendering them protein reactive. The process involves chlorosulfonation of the aromatic ring, sulfonamide formation with excess di‐ and triamines, and reaction of the residual pendant amines with various bifunctional molecules. Surfaces possessing pendant bromoacetyl, iodoacetyl, fluorodinitrophenyl, and trimellitic anhydride were prepared and can exhibit up to ten times more protein immobilization capability compared to unfunctionalized polystyrene, where the coupling takes place presumably via hydrophobic interaction.
Time–temperature–transformation (TTT) cure diagrams: Relationship between Tg and the temperature and time of cure for a polyamic acid/polyimide system
Authors: Palmese G. R. , Gillham J. K.
Published: April 2003

Glass transition temperatures (Tg) were obtained vs. isothermal temperature (Tcure) and time of cure for a polyamic acid/polyimide system. A time–temperature–transformation (TTT) isothermal cure diagram was constructed to include the time to vitrification and iso‐Tg curves. As for expoxies, the relationship between Tcure and the time to vitrification is S‐shaped. Plots of Tg vs. Tcure show that solvent evaporation and chemical reaction are controlled by vitrification.
Cooling and annealing properties of copolymer‐type polyacetals and its crystallization behavior
Authors: Chiang Wen‐Yen , Lo Ming‐Song
Published: April 2003

Copolymer‐type polyacetals (POMs) that have been cooled at seven different rates from the melt at 180°C to the solid at 23°C show average spherulite diameters from 10 to 25 μm on an etched fracture surface using scanning electron microscopy (SEM). The wide‐angle X‐ray diffraction (WAXD) of POM displays a degree of crystallinity ranging from 60 to 66% by applying the two‐phase model. From studies of mechanical properties, physical properties, and dielectric dissipation factor (tan δ), we found that POM with a faster cooling rate shows looser packing and smaller spherulites on the fracture surface than that with a slower cooling rate. This conclusion is in agreement with the observations made on SEM and WAXD. DSC measurements were used to measure the heat of fusion, melting point, and crystallization temperature of POMs. An equilibrium melting temperature was estimated from the Hoffman–Weeks plot. The overall crystallization kinetics of POMs were analyzed by the Avrami equation. Results for the Avrami exponent n, between 2 and 3, indicate small disklike spherulites following nucleation growth kinetics. Annealing the cooled POM at 150°C results in recrystallization featuring a significant increase in the average diameter of spherulites in SEM.
Synthetic resins. V. Preparation and properties of substituted benzoic acid, hydroxyacetophenone and aniline/formaldehyde resins
Authors: Das Anil P. , Nayak Padma L. , Lenka Subasini
Published: April 2003

A number of resin copolymers have been prepared by condensation of substituted aromatic compounds with formaldehyde in the presence of different acid catalysts. The resin copolymers were characterized by IR, thermal, X‐ray diffraction, and by their reactivity ratios. The resins were found to possess high thermal stability. Activation energies of resin degradation were computed using the Freeman–Anderson method. The antifungal activities of several previously synthesized resins were studied.
Water‐dispersible graft copolymer mixtures prepared by electron irradiation. I. Polymerization behavior
Authors: Egusa Shigenori , Sasaki Takashi , Hagiwara Miyuki
Published: April 2003

Highly viscous systems made up of 70 wt% epoxy resin dissolved in 30 wt% monomer mixtures of acrylic acid and styrene were irradiated with 1.5 MeV electrons to initiate graft copolymerization. The temperature measurement of the systems reveals that the polymerization reaction takes place both during and after the electron‐beam exposure of about 5‐sec duration. The reaction lasts about 50 sec for a low beam current of 0.6 mA, while for a high beam current of 6.0 mA it lasts merely about 20 sec. The gel permeation chromatography (GPC) measurement of obtained products demonstrates that the molecular weight distribution of ungrafted copolymer of acrylic acid and styrene becomes strikingly broader as the beam current is lowered. The GPC data suggest that the fraction of epoxy resin having a grafted branch increases with an increase in the beam current. All of these results are interpreted in terms of the mobility and the concentration of reactive species such as polymer radicals and low molecular weight free radicals.
Water‐dispersible graft copolymer mixtures prepared by electron irradiation. II. Dispersion behavior
Authors: Egusa Shigenori , Sasaki Takashi , Hagiwara Miyuki
Published: April 2003

Highly viscous systems made up of 70 wt% epoxy resin dissolved in 30% monomer mixture of styrene and acrylic monomers were irradiated with 1.5 MeV electrons to initiate graft copolymerization. The obtained product of graft copolymer mixture was fed into a mixed solvent of n‐butanol and cyclohexanone, and was heated 2 h at 70°C to form a predispersion. Then aqueous solution of 2‐dimethylaminoethanol or ethanol was added to the predispersion, thus giving a stable dispersion in water or in ethanol. The particle diameter of the aqueous and ethanol dispersions is practically the same, thus suggesting that polymer particles are virtually generated during the predispersing procedure, and at this step the size of the particles is actually determined. The particle diameter increases inversely proportional to the polymer concentration in the predispersion. Furthermore, the particle diameter shows a tendency to decrease with an increase in the hydrophilicity of monomers used in the graft copolymerization. The stopped‐flow measurement, on the other hand, reveals a characteristic pH dependence of the dispersion stability to the addition of NaCl. This result is interpreted based on a particle model consisting of a particle core of epoxy resin and its surrounding layer of acrylic copolymer.
Morphology of hydroxyapatite as suspension stabilizer in the polymerization of poly(styrene‐co‐butadiene)
Authors: Deslandes Yves
Published: April 2003

The morphology of the layer of hydroxyapatite that surrounds the polymer beads during the suspension polymerization of a random copolymer of styrene and butadiene is described. The layer is actually composed of two distinct parts: a thin layer made of very uniformly distributed hydroxyapatite primary particles and a second layer, usually much thicker, which is made of agglomerates of hydroxyapatite which are loosely packed. This second layer contains very small polymer beads, about 1 to 2 microns in diameter, that have polymerized at the droplet interface. Some of these smaller beads migrate into the bulk of the polymer during the polymerization contributing to the contamination of the polymer.
Wide‐angle x‐ray scattering study of heat‐treated peek and peek composite
Authors: Cebe Peggy , Lowry Lynn , Chung Shirley Y. , Yavrouian Andre , Gupta Amitava
Published: April 2003

We report the results of a study of poly(etheretherketone) (PEEK) neat resin and APC‐2 carbon fiber composite samples which were processed from the melt and then subjected to a variety of thermal treatments. Wide‐angle x‐ray scattering was used to study the effects of quenching and annealing treatments. For both neat resin and composite, annealing resulted in perfection of the crystalline microstructure. In addition to the crystalline and amorphous scattering usually observed, disorder is frozen‐in by fast cooling after heat treatment. The disordered component is detected as an additional low‐angle scattering peak at 14 degrees, well separated from the crystalline reflections, and is observed in low molecular weight material synthesized in our laboratory, and in commercially available neat resin PEEK and APC‐2 carbon fiber composite samples. When disordered material was subsequently heated above the glass transition, and then cooled very slowly, only the crystalline and amorphous scattering remained. Application of stress also resulted in formation of the disorder in the necked down regions of samples drawn in tension, suggesting that residual stresses may occur as a result of rapid cooling after heat treatment.
Mechanisms of antioxidant action: The effect of spin traps during the processing and photooxidation of PVC
Authors: Adeniyi J. B. , Al‐Malaika S. , Scott G.
Published: April 2003

It is demonstrated by the use of spin traps that during the early stages of thermal processing of PVC considerable concentrations (> 3 × 10−6 mol g−1) of free radicals are produced which are primarily responsible for the initial products (hydroperoxides, unsaturation, and hydrogen chloride) previously shown to be formed in the polymer. From a semiquantitative analysis of these products, it is estimated that more than 50% of the radicals are formed from hydroperoxides and the rest by mechanoscission of the polymer chain. The spin traps are effective processing stabilizers in combination with a tin maleate HC1 scavenger. One of them (2‐methyl‐2‐nitroso propane, MNP) has also been shown to be a photoantioxidant.
Novel thin‐film composite membranes containing photoreactive groups part I: Choosing the photoreactive group
Authors: Chadda S. K. , McCarry B. E. , Childs R. F. , Rogerson C. V. , Tse‐Sheepy I. O. , Dickson J. M.
Published: April 2003

Thin‐film composite membranes containing photoreactive groups have been developed. The presence of these groups facilitates the subsequent photochemical conversion of the membrane to include a range of different chemical moieties. For example, a cationic or an anionic membrane can be made from the same initial composite membrane. In this paper the selection of an appropriate photolabile group is investigated.
The reduction of orientation in fibers spun from two‐phase polymer blends via the introduction of shear into elongational flow by the presence of a second phase
Authors: Miles I. S.
Published: April 2003

A model is proposed for the reduction of orientation in spun fibers of two‐phase polymer blends. This is based on the introduction of shear into an elongational flow by the presence of a second phase. The requirement is that the dispersed phase should not deform to the same extent as the continuous phase so that the flow field in the region of each particle is perturbed. Around an isolated droplet of minor component, the shear rate in the continuous phase goes through a maximum when the extension rate in the droplet is around half that macroscopically imposed. The dependence of orientation reduction on concentration of dispersed phase is fitted well by assuming that the flow field around a particle is disturbed over a distance two to three times the particle diameter. In this case the maximum average shear rate around the particle is of the same order of magnitude as the elongation rate. The model proposed is consistent with all the observed features of orientation reduction during spinning of two‐phase blends.
Analysis of temperature‐dependent AC dielectric loss data
Authors: Bánhegyi György , Hedvig Péter , Karasz Frank E.
Published: April 2003

The analysis of dielectric loss data is frequently complicated by the presence of ohmic conductivity, especially at lower frequencies. Two simple methods are discussed for locating transition temperatures and for determining activation energies in such cases. In the first method the permittivity derivative [dε′(T)/dT] is used; in the second, permittivity difference spectra ε′(T, v1) – ε′(T, v2) (v1 ≪ v2 are used. The latter technique, however, cannot be used for activation energy determination. The theoretical basis of these methodologies and an analysis of representative experimental data are presented. The data set include measurements of pure and filled polyurethanes and of radiation‐cured unsaturated polyester resins. Finally, the advantages of data presentation in the form of ε′ and ε″ instead of tan δ are discussed.
Synthesis, physical and thermal characterization of phosphorus‐containing homopolymers and copolymers based on 2,4‐bis(4‐aminophenoxy)‐6‐diethoxyphosphinyl‐s‐triazine
Authors: Melissaris Anastasios P. , Mikroyannidis John A.
Published: April 2003

Novel phosphorus‐containing homopolyimides, homopolyamides, and homopolyureas were prepared by reacting 2,4‐bis(4‐aminophenoxy)‐6‐diethoxyphosphinyl‐s‐triazine (BADT) with pyromellitic or benzophenone tetracarboxylic dianhydride, terephthaloyl chloride, and tolylene diisocyanate, respectively. In addition, the corresponding copolymers that contained approximately 3% phosphorus were prepared by reacting BADT and 4,4′‐diaminodiphenyl sulfone with the aforementioned reagents. These polymers were characterized by inherent viscosity measurements, infrared (IR) and proton nuclear magnetic resonance (1H‐NMR) spectroscopy as well as by differential thermal analysis (DTA) and dynamic thermogravimetric analysis (TGA). Their thermal properties were compared with those of the corresponding nonphosphorylated polymers. The copolymers were stable up to 233–272°C in nitrogen or air atmosphere. The homopolymers showed a relatively lower thermal stability. Furthermore, a model diimide, diamide, and diurea were synthesized from the reactions of BADT with phthalic anhydride, benzoyl chloride, and phenyl isocyanate, respectively. The physical and thermal characteristics of these model compounds were correlated with those of the corresponding homopolymers.
Production of hydroxyl‐terminated liquid natural rubber—mechanism of photochemical depolymerization and hydroxylation
Authors: Ravindran T. , Nayar M. R. Gopinathan , Francis D. Joseph
Published: April 2003

Photochemical degradation of natural rubber yielded hydroxyl‐terminated liquid natural rubber (HTNR) when carried out in solution in presence of H2O2. Ultraviolet radiation from a medium pressure mercury vapor lamp and sunlight were found to be almost equally effective in bringing about the depolymerization and hydroxylation of natural rubber. The variations in the composition of the reagents and exposure time on the extent of depolymerization was conducted, and a suitable procedure for the large scale preparation of HTNR was described. A probable mechanism leading to the formation of HTNR as well as the side products is discussed based on the analytical data.