bluuebunny/crossref_metadata_2025 huggingface dataset:
Pervaporation of ethanol–water mixtures through styrene‐substituted N‐phenylmaleimide copolymer membranes
Authors: Lokaj J. , Bílá J.
Published: April 2003

A number of copolymers of styrene with substituted N‐phenylmaleimides were synthesized and their solutions in chloroform were used in the casting of homogeneous membranes. The latter were applied in the separation of variously concentrated ethanol—water mixtures by pervaporation at 35°C. The membranes were characterized by the separation factor related to preferentially transported water and by the flux of the permeate. In contrast to membranes made from copolymers of styrene with N‐phenylmaleimide, the separation factor of membranes containing substituted N‐phenylmaleimides increased with increasing amount of ethanol in the feed solution. The effect of incorporated imide units on the properties of the membranes under investigation is discussed. © 1992 John Wiley & Sons, Inc.
Solvent‐assisted graft copolymerization of acrylamide on poly(ethylene terephthalate) films using benzoyl peroxide initiator
Authors: Şanli Oya , Pulat Emsal
Published: April 2003

Graft‐copolymerization of acrylamide (AAm) on poly(ethylene terephthalate) (PET) films using benzoyl peroxide (Bz2O2) initiator has been studied. Four organic solvents, namely, pyridine (Py), 1,2‐dichloroethane (DCE), DEC/H2O (20/80, v/v), and dimethyl sulfoxide (DMSO), were used as swelling agents. DMSO was found to be the most suitable swelling agent. Solvent inclusion in the films increased with increased length of solvent treatment time and temperature. Elevated temperatures had a greater effect on the inclusion of swelling agents than did the length of swelling. Variation of graft yield with the type of solvent, initiator concentration, monomer concentration, temperature, and polymerization time were also investigated. The graft yield increased in the order of toluene, benzene, DMSO. The optimum temperature for grafting was found to be 70°C. The graft yield was observed to increase with monomer concentration and polymerization time, then reached a plateau. The graft yield increased up to a certain Bz2O2 concentration, then decreased. © 1993 John Wiley & Sons, Inc.
Gas sorption in poly(butylene terephthalate). I. Influence of gas molecules
Authors: Zhou Z. , Springer J.
Published: April 2003

The sorption of CO2 and the noble gases Ne and Ar in semicrystalline glassy poly(butylene terephthalate) (PBTP) films was measured by the gravimetric method with a recording microbalance at 298 K. The sorption of CO2 was found to be significantly higher than that of Ne and Ar. This is attributed to a specific interaction between CO2 and PBTP. The sorption isotherm for CO2 was analyzed by the dual‐mode sorption model, while the sorption behaviors for Ne and Ar did not follow this model. Their sorption isotherms can be described by the sorption model developed here for the noble gases in PBTP. A critical adsorption pressure p* that is dependent mainly on the relative size of the frozen microvoids and the noble gas atoms is defined in this model. The Langmuir adsorption for describing the sorption in this gas/polymer system in addition to Henry's solubility happens just above this p*, whereas only Henry's solubility takes place below p*. © 1993 John Wiley & Sons, Inc.
Investigations on vinylene carbonate. V. Immobilization of alkaline phosphatase onto LDPE films cografted with vinylene carbonate and N‐vinyl‐N‐methylacetamide
Authors: Chen Guohua , van der Does Leen , Bantjes Adriaan
Published: April 2003

Low‐density polyethylene (LDPE) films cografted with vinylene carbonate (VCA) and N‐vinyl‐N‐methylacetamide (VIMA) were studied as a matrix for the immobilization of the enzyme alkaline phosphatase (ALP) either by direct fixation or by inserting spacers. When water‐soluble alkyldiamines such as diaminoethylene, diaminobutane, diethylenetriamine, and diaminohexane were used as spacers between the matrix and the enzyme, the surface concentration (SC) of the active ALP coupled on the matrix was increased, whereas the effect of the spacer on the SC was dependent on the length of the spacer. Bovine serum albumin (BSA) was preimmobilized onto the LDPE films to provide a better simulation of the biological environment for the enzyme, and the SC of ALP on the matrix was significantly increased by coupling ALP onto the BSA preimmobilized surfaces. Compared to native ALP, some physicochemical properties of ALP could be improved by the covalent immobilization. © 1993 John Wiley & Sons, Inc.
Mechanism of the electrocopolymerization of styrene and N‐(3‐carboxyphenyl)maleimide onto graphite fibers in aqueous solution
Authors: Iroh J. O. , Bell J. P. , Scola D. A.
Published: April 2003

Electrochemical copolymerization of styrene and N‐(3‐carboxyphenyl)maleimide was performed in an aqueous sulfuric acid solution using AS‐4 graphite fibers as the working electrode. Cyclic voltammetric analysis results suggest radical initiation of polymerization via the reduction of the N‐(3‐carboxyphenyl)maleimide and sulfuric acid. Radical chain electrocopolymerization was strongly suggested by the inhibition of chain growth in the presence of hydroquinone and 2,2‐diphenylpicrylhydrazyl (DPPH). Compositional analysis of copolymers and reactivity ratios rs ∼ 0.014 and rm ∼ 0.041 for styrene and N‐(3‐carboxyphenyl)maleimide [N‐(3‐CMI)], respectively, confirmed a 1 : 1 alternating electrocopolymerization. Kinetic analysis shows a first‐ and 1/2‐order dependence of the rate of chain growth on initial monomer concentration and initiator concentration, respectively. A model incorporating these data is presented. © 1993 John Wiley & Sons, Inc.
Influence of microstructure on dynamic mechanical behaviour of polymeric composites with complex inclusions
Authors: Kim K. R. , An J. H. , Cho K. W. , Park C. E.
Published: April 2003

The dynamic mechanical properties of polymeric composites composed of crosslinked poly(n‐butyl methacrylate) continuous‐phase and crosslinked polystyrene dispersed phase with poly(n‐butyl methacrylate) occlusion have been examined. The composite samples were prepared by mixing and swelling of the crosslinked polystyrene particles obtained by emulsifier‐free emulsion polymerization, with n‐butyl methacrylate and crosslinker, then photopolymerizing at the desired temperature. The composite microstructure was varied by either changing the crosslink density of polystyrene, and temperature of swelling and polymerization, or using different sizes and contents of polystyrene particles. The tan δ peak positions of composite samples are found to be dependent on morphological characteristics as well as the properties of the dispersed phase while the peak height seems to be dependent on the effective volume of dispersed phase composed of polystyrene and poly(n‐butyl methacrylate) occlusions. Special attention has been paid to the comparison among composite, homonetworks, and bulk IPN samples that are expected to have the identical structure with the complex dispersed phase of the composite samples. © 1993 John Wiley & Sons, Inc.
Radiation initiated grafting of acrylic acid onto tetrafluoroethylene–ethylene copolymers
Authors: Kostov G. K. , Atanassov A. N.
Published: April 2003

Hydrophilic carboxyl containing fluoropolymers was obtained by radiation grafting of acrylic acid onto tetrafluoroethylene—ethylene copolymers with different compositions. By using simultaneous (60Co) and preirradiation (electron beam) techniques, the effect of the grafting conditions (monomer concentration, dose rate, dose, film thickness, etc.) on the degree of grafting was studied. A considerable effect of the polymer compositions, especially the CF bonds content, and the batch irradiation on the degree of grafting was found. It was observed by scanning electron microscopy that the grafting took place mainly on the polymeric film surface and developed inward with increasing diffusion of the acrylic acid through the grafted layers. © 1993 John Wiley & Sons, Inc.
Studies on the synthesis of block copolymers of acrylonitrile and ethylene oxide
Authors: Wódka Tadeusz
Published: April 2003

The synthesis of polyacrylonitrile–poly(ethylene oxide) block copolymers was carried out with the use of modified initiator containing azo groups, being a product of reaction between poly(ethylene oxide) (mol wt 6000) with azobisisobutyronitrile. Effects of initiator concentration, temperature, and synthesis time on the yield, composition, and intrinsic viscosity of the copolymers were examined. To confirm the segmental structure of the obtained products, precipitation, fractionation, gel permeation chromatography, infrared, and 1H nuclear magnetic resonance methods were used. © 1993 John Wiley & Sons, Inc.
Functional polymers for colloidal application. VI. Syntheses and dispersing ability of lipomodified naphthalenesulfonate formaldehyde condensates
Authors: Kuo Ping‐Lin , Lin Jiaau‐Shahng , Wey Bih‐Shiuh
Published: April 2003

Butyl‐substituted naphthalenesulfonate formaldehyde condensates (C4NSF) with different molecular weights were synthesized. The structures were confirmed by NMR in terms of the appearance of the signal at δ = 3.3–4.0 ppm, and the molecular weights of the synthesized C4NSFs were compared by gel permeation chromatography (GPC). C4NSFs used as dispersants were compared to unmodified naphthalenesulfonate formaldehyde condensates (NSF) in their ability to disperse nonpolar particles (carbon black) and polar particles (TiO2) in water. Their dispersing ability was evaluated by both a viscosity method and a microscopy method. For dispersing carbon black in water, it was found that using C4NSFs as dispersing agents results in a lower viscosity, a lower yield value by the viscosity method, and a more homogeneous dispersion of particles as determined by microscopy. These results indicate that the butyl group enhances the dispersing ability of C4NSF. The effect of the butyl group on the dispersing ability of C4NSF was interpreted by the results of the measured adsorption amount that was also enhanced by the existence of the butyl group. For dispersing TiO2 in water, C4NSF results in a higher viscosity and a higher adsorption amount of the dispersed system than NSF. These phenomena were interpreted in terms of the hydrophobic interaction between the butyl groups and the bridging effect. © 1993 John Wiley & Sons, Inc.
Viscoelastic behaviour of vinylic copolymers of cellulose and their glass transition temperature by DSC
Authors: Flaqué C. , Montserrat S.
Published: April 2003

The viscoelastic response of some vinylic copolymers of cellulose prepared with vinyl acetatemethyl acrylate mixtures and with Ce(IV) ion as initiator, and native cellulose, were studied at 110 Hz in a range of temperatures from −120–100°C.

The viscoelastic spectrum of cellulose shows the β‐relaxation that is not shown in its vinylic copolymers. We observed the same effect in the dielectric β‐relaxation.

For the vinylic copolymers of cellulose, one viscoelastic relaxation attributed to the α‐relaxation of the grafted vinylic chains is observed. Some differences in the characteristics of this relaxation may be related to the composition of PVA/PMA vinylic side chains and to the ratio of cellulose in the copolymer. The plots of the Argand diagrams give us a better understanding of the viscoelastic behaviour of these materials. The results seem to indicate that the cellulose hinders the large‐scale motions of the vinylic chains grafted onto it. The glass transition temperature (Tg) determined by differential scanning calorimetry (DSC) also shows the same fact: the Tg of the vinylic copolymers of cellulose are higher than both the Tg of polyvinyl acetate–polymethyl acrylate copolymers (PVA–PMA) without cellulose and the Tg of some blends of cellulose and the PVA–PMA whose composition was as similar as possible to the cellulosic copolymers. The importance of the covalent bonds between cellulose and the vinylic side chains in the structural transitions are revealed. The present results are compared with the dielectric α‐relaxation that we described elsewhere. © 1993 John Wiley & Sons, Inc.
The role of surfactants in synthesizing polyurea microcapsule
Authors: Chao D. Y.
Published: April 2003

Our lab has successfully synthesized microcapsules using interfacial polymerization technique. The core material and the wall of these microcapsules have been illustrated to be crystal violet lactone and polyurea, respectively, by both infrared and ultraviolet spectra. To make unique microcapsules, the presence of ethylene diamine in toluene diisocyanate system is important. Use of methyl cellulose with longer ethylene oxide chain length of nonylphenyl polyoxyethylene ether in a toluene diisocyanate system containing ethylene diamine will form small particles of polyurea microcapsules. Furthermore, in the presence of a fixed amount of sodium lauryl benzene sulfonate as an emulsifier, sodium carboxy methyl cellulose is better than methyl cellulose for use in making polyurea microcapsules in terms of their particle sizes. © 1993 John Wiley & Sons, Inc.
Sorption of water vapor by hydrophilic polyurethane‐ureas
Authors: Petřík S. , Hadobaš F. , Šimek L. , Bohdanecký M.
Published: April 2003

Segmented polyurethane‐ureas were prepared from low‐molecular weight homopolymers or triblock (PEP) copolymers of ethylene and propylene oxides and 4,4′‐diphenylmethane diisocyanate with hydrazine as chain extender. Equilibrium sorption of water vapor at 23°C was measured at eight to nine values of relative vapor pressure, 0.08 ≤ p/p0 ≤ 0.97. The effect of the structure (composition and length) of soft segments was studied. Sorption capacities were found to be lower than the reference values computed under the assumption that the contributions to sorption by the chain constituents are additive. This finding was assigned to the shielding effect of hard segment domains on the interaction of water molecules with hydrophilic (ethoxamer) groups of soft segments. © 1993 John Wiley & Sons, Inc.
Comparison of analytical and preparative TREF analysis: A mathematical approach to correcting analytical TREF data
Authors: Pigeon Michael , Rudin Alfred
Published: April 2003

Analysis of analytical temperature rising elution fractionation (TREF) data involves conversion of elution temperature information to branching information via a calibration curve relating the two. The curve is generated by analysis of polymer fractions recovered using preparative TREF techniques. In preparative TREF a stepwise temperature ramp is used to recover these fractions so that samples with sharp branching distributions are obtained. A continuous temperature ramp, as in analytical TREF, produces samples that differ in branching properties from the stepwise ramp at the same temperatures. The analytical TREF data can be corrected for these differences by an iterative computer program so that a calibration curve generated by preparative techniques can be used to convert the analytical TREF data to branching distributions. Analytical TREF results should be corrected for fraction overlap before relating these data to polymer properties. © 1993 John Wiley & Sons, Inc.
Grafting of poly(acrylonitrile) onto guar gum using potassium persulfate/ascorbic acid redox initiating system
Authors: Bajpai U. D. N. , Mishra Veena , Rai Sandeep
Published: April 2003

The grafting of poly(acrylonitrile) onto guar gum in aqueous medium initiated by the potassium presulfate/ascorbic acid redox system has been studied gravimetrically at the temperature of 35 + 0.2°C in the presence of atmospheric oxygen. A plausible mechanism of graft copolymerization has been suggested on the basis of experimental results. The effect of grafting on the water and saline retention capacities has been studied and compared with the values obtained for ungrafted guar gum. © 1993 John Wiley & Sons, Inc.
The phase behavior, mechanical, and rheological characteristics of blends containing nitrile polymers and poly(ethylene‐co‐maleic anhydride)
Authors: Percec Simona , Melamud Lucy
Published: April 2003

The phase behavior of binary blends of acrylonitrile/methyl acrylate/butadiene terpolymer (B210) and poly(ethylene‐co‐maleic anhydride) (PEMA) was examined based on thermal analysis and optical microscopy. Miscibility of these polymer blends was recognized over a wide range of compositions. The appearance of phase separation during subsequent heatings above the glass transition temperature (Tg) of these blends was associated with a lower critical solution temperature (LCST) behavior. Rheological characteristics such as shear storage modulus (G′), loss modulus (G″) and complex viscosity have been shown to depend on the amount of PEMA in the blend. Mechanical properties including the tensile strength and flexural modulus also were found to be related to the composition of the blend. © 1993 John Wiley & Sons, Inc.
A study of graft polymerization of methacrylic acid to polycaproamide using a reversible redox system containing CU2+ ions
Authors: Smirnova N. V. , Gabrielyan G. A. , Gal′Braikh L. S.
Published: April 2003

Graft polymerization of methacrylic acid to polycaproamide, initiated by the K2S2O8Na2S2O3Cu2+ reversible redox system, has been studied. Kinetic characteristics of graft polymerization have been investigated in a wide concentration range of every component of the initiating system. Cu2+ ions have been found to catalyze graft polymerization in the 1.0 · 10−5−1.2 · 10−4M concentration range, whereas at concentrations higher than 1.2 · 10−4M, Cu2+ ions are involved in the kinetic chain termination. A mechanism of graft polymerization is proposed. © 1993 John Wiley & Sons, Inc.
Analysis of volatiles evolved during high‐temperature treatment of thermally stable polymers. I. Nitrogen‐containing acetylene‐terminated resin
Authors: Mera Ann E. , Walton Theodore R.
Published: April 2003

Cured samples of a nitrogen‐containing acetylene‐terminated resin, N,N′‐(1,3‐phenylene‐dimethylidene)bis(3‐ethynylaniline), have been heated at 10°C/min up to 900°C in a pyroprobe attached to a gas chromatograph/mass spectrometer (GC/MS). Analysis of the volatiles evolved during heating identified both gases and higher boiling compounds. The major higher boiling compounds are benzene, toluene, xylene, aniline, benzonitrile, m‐methylaniline, and m‐methylbenzonitrile; the gases include ammonia, methane, and traces of carbon dioxide. Correlations between sample temperature and the evolution of each of these compounds have been made. The onset of all volatile formation occurs between 450 and 500°C. The higher boiling volatiles peak, then end by approximately 700°C, while the gases peak then fall off but are still being evolved at 900°C. Average weight loss measurements of 13.6% at 700°C and 15.7% at 900°C agree with previously published thermogravimetric analysis (TGA) data. © 1993 John Wiley & Sons, Inc.
Influence of polyacrylamide on the oxidative decomposition of sodium dithionite: Implications for vat dyeing processes
Authors: Etters J. N.
Published: April 2003

A statistical analysis was made of the halftimes of oxidative decomposition of sodium dithionite at 25°C in alkaline aqueous solutions, having geometrically spaced specific surfaces and concentrations of polyacrylamide. The analysis reveals a strong relationship between solution‐specific surface and resulting halftime, with halftime decreasing as specific surface increases; however, only the highest concentration of polyacrylamide, with a correspondingly high solution viscosity, is revealed to have a consistently significant effect on the rate of oxidative decomposition of dithionite. No significant effect on dithionite decomposition is observed for polyacrylamide concentrations that conceivably would be used in commercial vat dyeing processes. The findings suggest that the beneficial effect of high molecular weight polymers such as polyacrylamide in commercial vat dyeing is due solely to the function of the polymer to decrease the specific surface of the dithionite solution on the fabric, leading to decreased decomposition rates. © 1993 John Wiley & Sons, Inc.
Solubility and demixing of polyethylene in supercritical binary fluid mixtures: Carbon dioxide–cyclohexane, carbon dioxide–toluene, carbon dioxide–pentane
Authors: Kiran Erdogan , Zhuang Wenhao , Sen Yasar L.
Published: April 2003

Solubility of polyethylene in three different supercritical binary solvent systems—carbon dioxide–cyclohexane, carbon dioxide–toluene, and carbon dioxide–pentane—have been studied. Solvent compositions that lead to complete dissolution at pressures below 70 MPa have been identified. Demixing pressures have been determined for a range of polymer concentrations at temperatures up to 200°C. It is shown that the behavior of the solutions depends strongly on the fluid composition. In the composition ranges studied, solutions in cyclohexane–carbon dioxide mixtures were found to show lower critical solution temperature (LCST) behavior. It is found that the behavior of solutions in carbon dioxide–toluene and carbon dioxide–pentane mixtures shifts from upper critical solution temperature (UCST) to LCST with increasing toluene or pentane content. © 1993 John Wiley & Sons, Inc.
Preparation and permeability of solutes through acrylic acid‐g‐methylcellulose copolymer membranes
Authors: Huh Hoon , Lee Soon Hong , Lee Young Moo , Kim Kea Yong , Kim Jin Il
Published: April 2003

Graft copolymer membranes from the methylcellulose and the acrylic acid were prepared and their properties and the permeability of four solutes were estimated. Acrylic acid‐g‐methylcellulose (AA‐g‐MC) copolymer dissolved in aqueous acetone solvent was cast to prepare membranes followed by the subsequent crosslinking either with aluminium potassium sulfate or by the thermal‐curing method. The equilibrium water content in the membrane increased with the volume fraction of acetone in the aqueous acetone solvent system. Membrane, the ionically crosslinked with the aluminum potassium sulfate, showed the water content in the range of 38.5 and 58.4% and 0.25–0.33 kg/mm2 of the tensile strength in the wet state. Compared with ionically crosslinked membranes, thermally dried membranes exhibited a more dense structure, resulting in lower water contents and higher mechanical strength. Experimental results on the permeation of four small and midsize solutes through the graft copolymer membranes revealed the molecular weight dependence of the permeability coefficient. The higher the degree of swelling, the greater the permeability coefficient. Ionically crosslinked membranes had higher solute permeability than the commercial Cuprophane membrane had. © 1993 John Wiley & Sons, Inc.
Inhibition of deterioration of rubbers by hydroaromatics
Authors: Kubo Junichi
Published: April 2003

Based on the results obtained from our previous works, which concluded that hydrogen donating hydroaromatics can be available as radical scavengers in inhibiting the deterioration of hydrocarbon products at lower oxygen partial pressure, a hydroaromatic type inhibitor which contains various hydroaromatics as its main components produced from coal tar fraction was examined by adding it to natural rubber (NR) and styrene‐butadiene rubber (SBR). It was found that the inhibitor was as effective as the conventional aminetype inhibitor. From practical viewpoint, heavy hydroaromatics from petroleum (HHAP) was produced by the hydrogenation of the highly aromatic oil from the heavy fraction of petroleum to improve the physical properties of the previous inhibitor from coal tar fraction. From the deterioration tests for NR, SBR, and chloroprene (CR), the following results could be obtained: (1) HHAP showed excellent inhibiting abilities toward NR and CR, exceeding the conventional inhibitor; (2) inhibiting effect toward SBR could be recognized, but it was not so high as the conventional one; (3) physical properties such as Mooney viscosity and flex cracking were improved by the addition of HHAP. From these results, the hydrogen donation from hydroaromatics is considered to be effective in inhibiting the deterioration of rubbers. © 1993 John Wiley & Sons, Inc.
Toughness improvement of an epoxy/anhydride matrix. Influence on processing and fatigue properties of unidirectional glass–fiber composites
Authors: Urbaczewski‐Espuche E. , Gerard J. F. , Pascault J. P. , Reffo G. , Sautereau H.
Published: April 2003

Wet filament winding processing for unidirectional composites uses specific reactive systems with low viscosity and long‐pot life. This work describes improvement of toughness of an epoxy/anhydride matrix using, first, the increasing of the average molecular weight of the diepoxy prepolymer and, second, the introduction of a functionalized elastomer. Thermomechanical behaviors (glass transition temperature, elasticity, plastic, and fracture properties) are discussed in terms of (1) the increase of the average molecular weight between crosslinks in the first case and(2) the amount of elastomer dissolved in the matrix in the second case. Dynamic mechanical spectroscopy confirms that phase separation occurred, during curing, between the epoxy system and the elastomer. A good correlation is obtained between matrix toughness and fatigue behavior of unidirectional composites. © 1993 John Wiley & Sons, Inc.
Sulfur‐free lignins as composites of polypropylene films
Authors: Košíková B. , Demianová V. , Kačuráková M.
Published: April 2003

To elucidate the effect of lignin addition, polypropylene films containing 2–10 wt % of spruce organosolv lignin and/or beech wood prehydrolysis lignin were compared with lignin‐free polymers with respect to tensile strength and elongation before and after aging. The physicochemical properties of the lignin‐containing films were investigated by conductivity measurements, surface behavior, and UV and IR spectroscopy. © 1993 John Wiley & Sons, Inc.
Evaluation of interfacial adhesion in sheath/core composite fibers
Authors: Tao Weiying , Collier John R. , Collier Billie J.
Published: April 2003

Rayon/nylon sheath/core composite fibers were produced using a wire coating‐type process. Fumaric acid (FA) was chosen as an adhesion promoter to pretreat the nylon core fiber before rayon coating to improve the adhesion between skin and core. Different FA pretreatment concentrations and times were used and the effects of the pretreatment conditions on the adhesion were evaluated. A fiber pull adhesion test technique was developed to determine the interfacial shear strength of the composite fibers. The results indicated that the interfacial adhesion in the rayon/nylon composite fibers was significantly improved for specific sets of FA application conditions. Adhesion results were confirmed with electron microscopy. © 1993 John Wiley & Sons, Inc.
Morphological effects of ballistic impact on fabrics of highly drawn polyethylene fibers
Authors: Desper C. Richard , Cohen Samuel H. , King Abram O.
Published: April 2003

Changes in crystalline structure of high‐tenacity ultra‐high‐molecular‐weight polyethylene fabric brought on by ballistic impact from a small projectile were determined by X‐ray diffractometry. A suitable X‐ray diffraction method that averages out the fiber orientation effects in the diffraction pattern was used. The Spectra 1000™ polyethylene fabrics were successfully characterized in terms of both the predominant orthorhombic and the minor monoclinic crystal content. Crystallinity values for the undamaged fabric are consistent from sample to sample and show an average orthorhombic fraction of 0.61 and an average monoclinic fraction of 0.04. Fabric damage by the projectile impact results in either an increase in monoclinic fraction, attributed to recrystallization at temperatures nearing the normal polyethylene melting point, or disappearance of monoclinic material as that temperature is exceeded. The latter predominates where ballistic penetration is complete. However, actual melting need not be involved: Transformation to the hexagonal (“rotator”) phase and the disappearance of the monoclinic phase could have occurred rather than true melting. © 1993 John Wiley & Sons, Inc.
Effect of steric restrictions on the enhancement of miscibility through hydrogen bonding in blends of modified poly(α‐methyl styrene) with polymers containing acceptor sites
Authors: Cowie J. M. G. , Reilly A. A. N.
Published: April 2003

Two series of copolymers have been prepared from α‐methylstyrene and α‐methylstyrene units modified by the incorporation of the hydrogen‐bond donor units, methyl carbinol and trifluoromethyl carbinol, designated PαMS (I) and PαMS (II), respectively. It has been observed that if the concentration of the donor unit exceeds 4 mol %, one‐phase blends can be prepared with a series of polymers containing hydrogen‐bond acceptor sites such as poly(vinyl acetate), poly(vinyl pyrrolidone), poly(4‐vinyl pyridine), and some poly(alkyl acrylate)s, none of which are miscible with the unmodified PαMS. All the one‐phase blends formed are stable at temperatures above the glass transition temperature, Tg, of the blend, but eventually phase separate when the temperature is increased sufficiently. These lower critical cloud‐point curves have been measured for a wide range of the blends and act as an indicator of the effectiveness of the hydrogen bonds in enhancing one‐phase blend formation. The Tg's of the blends are in many cases higher than those calculated from the simple rule of mixtures and reflect the reduction in chain mobility in the blends caused by extensive hydrogen bonding. The results demonstrate the effect that specific interactions have in enhancing miscibility in binary polymer blends. © 1993 John Wiley & Sons, Inc.
Adhesion properties of glow‐discharge‐plasma‐treated polyethylene surface
Authors: Yu. Kuznetsov A. , Bagryansky V. A. , Petrov A. K.
Published: April 2003

A geometric method proposed by Kaelble and Moacanin for analyzing energetic characteristics of solid surfaces is discussed. It is shown that a number of characteristics can be presented in a visual geometric form. The method is applied to the analysis of adhesion in a three‐component system. Results of the analysis, concerned with the problem of creation of biocompatible materials, support the Andrade hypothesis that materials with zero interfacial tension of their water–solid interface show maximum biocompatibility. Data are obtained on wetting of polyethylene by different liquids before and after glow discharge plasma treatment. The analysis of these data in terms of geometric method shows the plasma treatment increased the polar component of the polymer surface energy to change the surface adhesiveness toward probable enhancement of polymer biocompatibility. That is consistent with available data on glow‐discharge‐treatment enhancement of biocompatibility for a number of polymers. © 1993 John Wiley & Sons, Inc.
Flammability and thermal behavior of phosphorus‐containing polyamide‐6
Authors: Mateva Rosa P. , Dencheva Nadya V.
Published: April 2003

An investigation is reported on the flammability and thermal behavior of polyamide‐6, obtained by anionic polymerization of ϵ‐caprolactam, carried out in bulk, in the presence of the following N‐substituted phosphorus‐containing lactam derivatives: diethyl‐(N‐caprolactam)‐phosphonite (PL1), diethyl‐(N‐caprolactam)‐phosphonate (PL2), and 2,5‐dichlorophenyl‐bis(N‐caprolactam)‐phosphinate (PL3). Phosphorus‐containing lactam derivatives PL,1 and PL3 are used as activators of the anionic polymerization of ϵ‐caprolactam, and PL2, as a modifying additive. The phosphorus‐containing polyamide‐6 possesses improved flame retardancy, as well as improved thermo‐ and thermooxidative resistance. Destruction kinetics were studied in nitrogen and air atmospheres, and the activation energy for thermal and thermooxidative destruction have been determined. The effect of PL1 PL2, and PL3 on the melting temperature (Tm) and glass‐transition temperature (Tg) of polyamide‐6 was established. © 1993 John Wiley & Sons, Inc.
The structure of crosslinked poly(glyceryl methacrylate) hydrogel networks
Authors: Leung Billy Kar‐On , Robinson Garth B.
Published: April 2003

Poly(glyceryl methacrylate) hydrogels with different degrees of hydration (75–98% H) and cross‐linking densities (X = 0.005–0.05 mol tetraethylene glycol dimethacrylate/mol glyceryl methacrylate) have been prepared by solution polymerization. Cross‐linking densities of the fully swollen hydrogels were analyzed using a modified Flory equation. Poly(glyceryl methacrylate) gels polymerized with no added cross‐linker were found to be highly cross‐linked, the degree of cross‐linking depending upon monomer dilution at polymerization. Modeling studies indicated that entanglement of polymer chains explained the highly cross‐linked nature of these materials. Gels polymerized with tetraethylene glycol dimethacrylate exhibited higher cross‐link densities than did gels polymerized with no added cross‐linker. However, for gels polymerized with cross‐linker, but at different initial dilutions, cross‐linking densities varied depending upon initial concentration, indicating that entanglement contributed appreciably to cross‐linking. These hydrogels may be regarded as highly swollen entangled networks, contrary to previous views. Correlation of these findings with those from earlier studies on the ultrafiltration behavior of the poly(glyceryl methacrylate) hydrogels suggested that the packing density of polymer fibers in the matrix may be more predictive of ultrafiltration behavior than is mesh size. © 1993 John Wiley & Sons, Inc.
The modification of secondary high molecular weight guayule rubber with metachloroperoxybenzoic acid
Authors: Thames S. F. , Poole P. W.
Published: April 2003

The epoxidation of secondary high molecular weight guayule rubber has been accomplished. The reaction is performed using metachloroperoxybenzoic acid as the epoxidation agent in various stoichiometric ratios including 5, 10, 20, and 50 mol %. The products were characterized by infrared spectroscopy, 1H‐ and 13C‐nuclear magnetic resonance (NMR), differential scanning calorimetry, and elemental analysis. 1H‐NMR is used quantitatively to calculate epoxidation levels that are compared to stoichiometry. DSC results record a linear relationship between percent epoxidation and Tg. © 1993 John Wiley & Sons, Inc.
Synthesis and conformational properties of poly(N4‐1‐phenylethyl‐L‐asparagines)
Authors: Chen Yun , Jung Shin‐Shing , Wang Jenn Hwa
Published: April 2003

Poly(N4‐1‐phenylethyl‐L‐asparagines) (1a, 1b, and 1c) containing DL‐, (R)‐, and (S)‐ side group chirality were prepared by aminolysis of poly(β‐methyl‐L‐aspartate) (PMLA) with DL‐, (R)‐ (+)‐, and (S)‐ (−)‐1‐phenylethylamine, respectively. The PMLA was synthesized by ring‐opening polymerization of β‐methyl‐L‐aspartate‐N‐carboxy anhydride (NCA) using triethylamine as initiator. The conformations of these polypeptides in the film state were investigated by IR and circular dichroic spectra. The PMLA, 1a, and 1b exist mainly in β‐sheet conformation, while 1c forms α‐helix that is induced by the (S)‐chirality of the side groups. © 1993 John Wiley & Sons, Inc.
Emulsion pathway for gelatin cross‐linking
Authors: Xu G. , Ruckenstein E.
Published: April 2003

A new method for gelatin cross‐linking is suggested that starts with the generation of an emulsion between an aqueous solution containing gelatin and a surfactant, and a monomer (MMA) that contains an initiator (AIBN). The emulsion is prepared at 50°C under intense stirring, but is brought, subsequently, to room temperature. There are conditions under which the gellike emulsions thus obtained are transparent and extremely stable at room temperature. A slow cross‐linking reaction occurs in the latter gels that leads to a material that is insoluble in water. The swelling of this material in water, which is very large after 5 days, reduces appreciably after 25 days of reaction. The cross‐linking occurs only when MMA contains the initiator. © 1993 John Wiley & Sons, Inc.
Effects of film thickness and inhibitor concentration on the sorption and thermal polymerization of acrylic acid in low‐density polyethylene
Authors: Sales Maria José Araújo , De Barros Glaucione Gomes
Published: April 2003

We investigated the effects of hydroquinone monomethyl ether concentration and film thickness upon the thermal polymerization of acrylic acid on low‐density polyethylene. The thermal polymerization of acrylic acid on low‐density polyethylene depended on the concentration of hydroquinone monomethyl ether inhibitor. It was a free‐radical reaction with initiation on the film surface and then proceeding to the bulk matrix. The process was not controlled by monomer diffusion for the range of film thickness of 90–200 μm. It became a diffusion‐controlled process at higher film thicknesses ( > 200 μm). A film layer of up to 100 μm was proposed as the limiting thickness for a diffusion‐free process. © 1993 John Wiley & Sons, Inc.
Aging and performance of structural film adhesives. IV. A modified epoxy with improved ambient temperature shelf life
Authors: Pearce P. J. , Ennis B. C.
Published: April 2003

It appears that improved latency in nitrile epoxy adhesives can be achieved by replacing the commonly used urea accelerator with one of much reduced solubility but similar chemical activity. A new, commercially available film adhesive claimed to possess a shelf life of 1 year at 22°C, excellent resistance to humidity prior to cure, and a service temperature range of −55 to 120°C has been examined. Areas studied included characterization, cure kinetics, adhesive performance, and shelf life. Its composition was found to be a variant of the 120°C curing nitrile—epoxy systems using a urea‐accelerated dicyandiamide cure. Two novel features were noted: the presence of bisphenol S and the urea 1,1'‐p‐phenylene‐bis(3,3‐dimethyl) urea. The relatively high shear strength found at elevated temperatures could be related to the adhesive's high Tg of 155°C resulting from the addition of bisphenol S and the improved room‐temperature latency was due to the ultralow solubility of the urea accelerator. Good durability was obtained from aluminum joints prepared using a simple silane pretreatment. Aging experiments indicated a shelf life of at least 3 months at 23°C under both dry and wet conditions, and it is predicted that adhesives of this type of composition would be stable for at least 1 year at normal domestic refrigeration temperatures of 5–10°C. © 1993 John Wiley & Sons, Inc.
Graft copolymers from modified ethylene–vinyl acetate (EVA) copolymer. I. Synthesis of poly(ethylene‐co‐vinyl acetate‐g‐styrene) using EVA modified by mercaptoacetic acid as chain transfer agent
Authors: Barbosa Ronilson V. , Soares Bluma G. , Gomes Ailton S.
Published: April 2003

The modification of the poly(ethylene‐co‐vinyl acetate) (EVA) by direct esterification of its ethylene—vinyl alcohol copolymer with mercaptoacetic acid was carried out. The amount of the mercaptan group was controlled to avoid gel formation during the graft polymerization with styrene by chain transfer. The chain transfer constant (Cs) of the SH groups and graft efficiency were measured. These graft copolymers were evaluated as a blend compatibilizer. © 1993 John Wiley & Sons, Inc.
Radiation‐grafting of acrylic acid onto ultrahigh molecular, high‐strength polyethylene fibers
Authors: Kaji Kanako , Abe Yoshinori , Murai Masaki , Nishioka Noboru , Kosai Kouichi
Published: April 2003

Radiation‐induced grafting of acrylic acid onto ultrahigh molecular weight (UHMW) high‐strength polyethylene fibers to impart heat resistance and dyeability was undertaken. A preirradiation method was employed for grafting in an aqueous solution of acrylic acid containing a small amount of Mohr's salt as inhibitor. The grafting rate for UHMW high‐strength polyethylene fibers is one‐tenth of that for high‐density polyethylene fibers currently in use, and one‐hundredth, for high‐density polyethylene film. It has become clear that the preirradiation dose should be as low as 1 Mrad to keep the high strength of the starting fibers. The starting UHMW high‐strength polyethylene fiber begins to shrink remarkably at around 145°C, showing a maximum shrinkage of 90%, and then breaks at 154°C. When a 24% acrylic acid graft is converted to calcium salt, the grafted fiber retains the fiber form even at 300°C and gives only a maximum shrinkage of 11%. The less than 1% acrylic acid graft UHMW high‐strength polyethylene fibers and their calcium salt can be dyed to a deep shade with cationic dyes, whereas the starting fibers cannot be dyed with usual dyes including the cationic dye. © 1993 John Wiley & Sons, Inc.
Influence of gelling conditions on mechanical properties of simultaneous interpenetrating polymer networks from epoxy and bismaleimide resins
Authors: Iisaka Katsuyoshi
Published: April 2003

Simultaneous interpenetrating polymer networks (SINs) were prepared from nadic methyl anhydride‐cured epoxy resin and bismaleimide (BMI) of which the composition ratios were, respectively, comprised of 3/1 (EM‐25 series) and 1/1 (EM‐50 series), under different gelling conditions for both resins. Dynamic mechanical and tensile properties were measured for these SINs. Turbidity was also measured to obtain some information regarding morphology. Although the rubbery modulus was constant irrespective of a gel‐time ratio (Gt) of the epoxide resin to that of BMI for the EM‐25 series, it increased with increasing Gt for the EM‐50 series. The glass transition temperature (Tg) was nearly constant at Gt < 1 and then decreased with increasing Gt at Gt > 1 for the EM‐25 series. On the other hand, Tg was nearly constant irrespective of Gt for the EM‐50 series, though the values of Tg at Gt < 1 were somewhat higher than those at Gt > 1. There was an appropriate value of Gt that gave better tensile strength (σb) or toughness evaluated by the area under a stress‐strain curve. The Tg and σb were found to be correlated to the turbidity of the SINs. The above mechanical behavior can be explained in terms of the molecular mixing and morphology that vary with a change in the relative polymerization rate of both the resins. © 1993 John Wiley & Sons, Inc.
Propylene polymerization with Mg(OEt)2/benzoyl chloride/TiCl4–triethyl aluminum/external donor catalyst systems
Authors: Lee Dong‐Ho , Jeong Young‐Tae , Soga Kazuo , Shiono Takeshi
Published: April 2003

Mg(OEt)2/benzoyl chloride (BC)/TiCl4 catalyst has been prepared by the chemical reaction method, and the chemical composition and X‐ray structure of the catalyst were studied. The effect of various conditions on catalyst activity and isospecificity were also examined. With 13C‐NMR analysis, it was found that aluminum carbinolate is formed during polymerization by reaction of triethyl aluminum cocatalyst with BC remaining in the prepared catalyst. The formed aluminum carbinolate acts as an additional donor to increase the isotactic index of polypropylene (PP). The morphology of the prepared catalyst and PP was also observed. © 1993 John Wiley & Sons, Inc.
Reactivity ratios and thermal and dielectric studies of n‐butyl methacrylate and methacrylamide copolymers
Authors: Srinivasulu B. , Rao P. Raghunath , Sundaram E. V. , Sathaiah G. , Sirdeshmukh Lalitha
Published: April 2003

Free‐radical copolymerization of n‐butyl methacrylate (B) and methacrylamide (M) was carried out in the presence of 2,2'‐azobisisobutyronitrile (AIBN) in dimethyl formamide (DMF) at 60°C. The percentage composition of the copolymers was established by elemental analysis. The reactivity ratios as determined by the Finemann—Ross (F—R) and the Kelen–Tüdős (K—T) methods are r1 (B) = 2.75 ± 0.01, r2 (M) = 0.2 ± 0.01 and r1 = 2.70 ± 0.05, r2 = 0.19 ± 0.02, respectively. The copolymers were characterized by IR, 1H‐NMR, thermal, and dielectric studies. Glass transition temperature (Tg) values were determined by DSC. Dielectric studies were carried out to understand the segmental motions and the effect of composition on dielectric loss. © 1993 John Wiley & Sons, Inc.
Homo‐ and copolymers of furan–maleic anhydride and furan–dimethylacetylene dicarboxylate adducts via aqueous ring‐opening metathesis polymerization
Authors: Viswanathan Tito , Jethmalani Jagdish , Toland Alan
Published: April 2003

Homo‐ and copolymers of the Diels‐Alder adduct of furan with maleic anhydride (F‐MA) and of furan with dimethylacetylene dicarboxylate (F‐DMAD) were synthesized by aqueous ring‐opening metathesis polymerization and characterized by IR, NMR, and DSC. Microstructural product analyses by 13C‐NMR indicated the copolymer composition to be 50 : 50 of each of the monomers when an equimolar mixture of RuCl3 and K2RuCl5, was used as the catalyst, with the cis‐form predominant for poly(F‐MA) and the trans‐form predominant for poly(F‐DMAD). On the practical side, the acidic and ester functionality of the copolymer would lend itself to be both blendable (and selectively extractable) with some already existing petroleum‐based acrylate polymers. © 1993 John Wiley & Sons, Inc.
The synthesis of polyethylene glycol (PEG) with different functional groups at each end. II. Synthesis of a series of monosubstituted PEG via polyvinyl alcohol (PVA) as support
Authors: Huang Junlian , Hu Youqian
Published: April 2003

Five monosubstituted PEGs with different mol wt were synthesized and isolated using PVA as support. They were , respectively. The structure of these monosubstituted PEGs was characterized by IR, NMR, and element analysis. The effect of the reaction conditions on monosubstitution of PEGs was described. © 1993 John Wiley & Sons, Inc.
Linear polythioesters. XVIII. Products of interfacial polycondensation of bis(4‐mercaptophenyl)sulfide with aliphatic and aromatic acid dichlorides
Authors: Podkościelny Wawrzyniec , Rudź Wieslaw
Published: April 2003

New polythioesters were synthesized by interfacial polycondensation of bis(4‐mercaptophenyl)sulfide with aliphatic and isomeric phthaloyl chlorides. To determine the optimal conditions for polycondensation, we studied the influence of the following factors on the yield and reduced viscosity: type of organic solvent, concentration and molar ratio of monomers, ratio of aqueous to organic phase, concentration of hydrogen chloride acceptor (NaOH), acid chloride excess, rate of addition of acid chloride, the temperature of reaction, and the kind and the contribution of catalyst. A thorough examination was carried out for the polycondensation of dithiol, with sebacoyl and isophthaloyl chlorides chosen as a model systems. Polythioesters from aliphatic dichlorides were prepared under the optimal conditions used for sebacoyl chloride. For polythioesters from phthaloyl and terephthaloyl chlorides, the conditions were those used for isophthaloyl chloride. The structure of polythioesters was determined from infrared, X‐ray, and elementary analysis. Some physicochemical, thermal, mechanical, and electrical properties are reported. © 1993 John Wiley & Sons, Inc.
Surface properties and platelet adhesion characteristics of acrylic acid and allylamine plasma‐treated polyethylene
Authors: Ko Tze‐Man , Cooper Stuart L.
Published: April 2003

Acidic oxygen‐containing and basic nitrogen‐containing functional groups were incorporated onto thin films formed by plasma polymerization of acrylic acid and allylamine in a lowpressure glow discharge. ESCA, ATR–FTIR spectroscopy, and static contact‐angle measurements confirmed the presence of these functional groups. Surface hydrophilicity of the acrylic acid plasma polymer decreased with time due to the diffusion of hydrophilic oxygencontaining functional groups away from the surface of the plasma‐treated polyethylene. In contrast, the hydrophilicity of the allylamine plasma polymer increased with time because of the extensive post‐plasma‐treatment oxidation with atmospheric oxygen. In assessing the blood compatibility of these two types of plasma polymer surfaces by platelet adhesion and spreading, the acidic acrylic acid plasma polymers showed an improvement in thromboresistance, but the basic allylamine plasma polymers were more thrombogenic than was the untreated low‐density polyethylene base material. © 1993 John Wiley & Sons, Inc.