bluuebunny/crossref_metadata_2025 huggingface dataset:
Processing–property interactions in poly(vinylidene fluoride). II. Morphology and property characterization of extruded films
Authors: Khomami B. , McHugh A. J.
Published: April 2003

The effects of flow history, processing temperature, and exit draw ratio have been studied for a poly(vinylidene fluoride) resin. Quantification of the stress fields and flow kinematics were described in Part I while, in this publication, attention has been addressed to the evaluation of film properties. Hot‐stage and differential scanning colorimetry (DSC) analyses were used to characterize the thermal behavior; polarized light optical microscopy and electron microscopy were used to characterize the morphology; Fourier transform infrared (FTIR) and wide‐angle x‐ray scattering (WAXS) were used to evaluate crystal structure; and mechanical testing was used to evaluate tensile properties. Extensional melt stresses on the order of 1.4 × 106 dyne/cm2 were necessary to induce row‐nucleated crystallization in undrawn samples, and in all cases, preorientation of the melt by extensional flow enhanced the efficiency of the α → β transformation with drawing. The various transformations on drawing were as follows: unoriented α to oriented superheatable α phase for draw ratio (DR) < 5; transformation from α to β phase for 5 < DR ≤ 25; transformation to more highly oriented α and β phases, DR > 25.
Hot nip drawing: A rapid method of producing high modulus polypropylene films
Authors: Laughner M. P. , Harrison I. R.
Published: April 2003

There are many methods currently producing high modulus and high strength films and fibers in industry. This publication examines the results of a hot nip drawing process to produce high modulus PP films at a relatively rapid production rate. The effects of both temperature and rate of draw on the drawn material will also be examined.
Effects of brominated flame retardants and crosslinking agents on the flame retardancy of rubbers
Authors: Yang Chin‐Ping , Chen Wen‐Tung
Published: April 2003

Tetrabromo‐p‐cresol (TBPC), pentabromophenol (PBP), and their allyl ether derivatives—tetrabromo‐p‐cresol allyl ether (TBPC–AE) and pentabromophenol allyl ether (PBP–AE)—were used in the study of flame retardancy of ethylene–vinyl acetate (EVA) copolymer and styrene–butadiene rubber (SBR), which were cured by dicumyl peroxide (DCP) and sulfur, respectively. The dependence of the flammability of crosslinking polymers on the polymer matrix, its additives, and the degree of crosslinking was investigated. The empirical equations of flame retardancy were established for these rubbers and compared with the measured values. It was found that the oxygen index of SBR–S system was in accordance with the empirical equations, while the EVA–DCP system, affected by the decomposed residue of DCP, showed a slight deviation. The brominated phenolic compounds of allyl ether (BPs–AE) showed a greater deviation than their precursors. This may be due to the fact that allyl group could react with DCP and lose its excellent flame resistance characteristic, which may be caused by the modified Claisen rearrangement produced in the thermal processing or burning. The phenolic brominated compounds containing the allyl group and a higher bromine content showed better flammability.
Characterization of water‐soluble cellulose derivatives produced by alkali treatment of ozonized allylated celluloses
Authors: Kondo Tetsuo , Ishizu Atsushi , Nakano Junzo
Published: April 2003

Ozonization products of allylated celluloses such as completely allylated methylcellulose and tri‐O‐allylcellulose, which are insoluble in both organic solvents and water, gave water‐soluble derivatives by alkaline treatment. Infrared (IR) and 13C‐NMR (nuclear magnetic resonance) spectrometries revealed that the products have many carboxyl as well as carbonyl groups. Allyl ethers in allylated celluloses were found to be cleaved by 30–35% during ozonization, whereas alkyl ethers such as methyl and ethyl ethers in cellulose derivatives were completely stable.
Flameproofed polyesters prepared by direct polycondensation of aromatic dicarboxylic acids and brominated bisphenols with tosyl chloride and N,N′‐dimethylformamide in pyridine
Authors: Yang Chin‐Ping , Hsiao Sheng‐Huei
Published: April 2003

Brominated aromatic polyesters were successfully prepared by reacting isophthalic acid and terephthalic acid with p‐toluenesulfonyl chloride in pyridine in the presence of N,N′‐dimethylformamide, followed by treating with a pyridine solution of tetrabromobisphenols. The tetrabromobisphenols were synthesized by a facile bromination of their corresponding bisphenols in aqueous acetic acid solution under mild conditions. The polycondensation was significantly affected by the reactivity of bisphenols and the solubility of the resulting polymers in the reaction media. Tetrabromobisphenols with positive linking groups between the aromatic rings and better solubility of the resulting polymers give a more favorable result. The products were nonflammable having limiting oxygen index 59–62 (ASTM D2863‐77) without much sacrifice in thermal stability.
The dyeability and properties of some structurally modified poly(ethylene terephthalate) filaments
Authors: Ugbolue S. C. O. , Ekpenyon O. E.
Published: April 2003

The effect of solvent treatment on the dyeability and mechanical properties of drawn poly(ethylene terephthalate) (PET) filaments has been studied. It is observed that strongly interacting solvents such as N,N‐dimethyl formamide (DMF) improved the dyeability of PET which has been treated with these solvents at 74°C for 15 min before dyeing with disperse dyes at 100°C. Pretreatment in N,N‐dimethyl formamide and acetonitrile also resulted in a lowering of tensile strength and initial modulus, whereas subsequent dyeing caused further reduction in extensibility but initial modulus results are less consistent.
Polyester formation: Aminolytic degradation and proposed mechanisms of the reaction
Authors: Popoola V. A.
Published: April 2003

The acid‐catalyzed chemical degradation of polyesters is discussed, with emphasis on the chemistry of the reactions involved. Using primary amines as degrading agents in presence of water as the acid‐ionizing medium, mechanisms consistent with the chemistry of the reaction and those of realted esters are proposed.
Properties of copolymer‐type polyacetal/polyurethane blends
Authors: Chiang Wen‐Yen , Lo Ming‐Song
Published: April 2003

Mechanical and physical properties of the blends of copolymer‐type polyacetals (POM) with polyurethane (PU) were investigated. The properties relationships of POM/PU blends are established by studying their morphology and compatibility. For the blends rich in POM, the morphology of the blends observed with a scanning electron microscopy (SEM) indicates that the blends containing lower than 50 wt % (46 vol %) PU are almost completely filled with spherical particles of the dispersed PU. As the concentration of PU increases, the spherulites of the POM observed by SEM become less perfect with coarse fine structure. Furthermore, when the concentration of PU was increased up to 50 wt %, the spherulties of POM in the blends are smaller than those of unblended POM. X‐ray diffraction studies reveal that the degree of crystallinity of POM decreases with increasing PU content, which is nonmonotonic. This conclusion agrees with the observations made by differential scanning calorimetry (DSC) and density measurements. For the blends rich in POM, mechanical properties show that the impact strength of POM/PU blends increased with decreasing spherical size of the dispersed PU.
Preparation and properties of UV‐curable poly(dimethylsiloxane) urethane acrylate. II. Property‐structure/molecular weight relationships
Authors: Chiang Wen‐Yen , Shu Wey‐Jye
Published: April 2003

A series of UV‐curable polyurethane acrylate resins based on hydroxy‐terminated polydimethylsiloxane (PDMS) soft segments with different molecular weights and various diisocyanate hard segments were synthesized. The products were obtained by employing direct‐addition polymerization techniques in a nonsolvent system. The structures of the final products were elucidated by IR and 1H‐NMR. The fundamental and physical properties of this type of UV‐curable material, the effects on properties by varying the molecular weight of PDMS or the type of diisocyanates, and the effect of using various reactive diluents were widely studied. This resin possessed good optical, electrical insulating, and adhesive properties. The mechanical strength of UV‐cured films corresponds approximately to the ratio of hard segments within these material and the dielectric insulating properties correspond to the chain length of PDMS.
Aging and performance of structural film adhesives. III. Effect of humidity on a modern aerospace adhesive
Authors: Ennis B. C. , Pearce P. J. , Morris C. E. M.
Published: April 2003

The aging of an uncured, DGEBA‐based commercial film adhesive exposed to high humidity at 40°C was monitored by high performance liquid chromatography (HPLC), thermal analysis, solubility, flow, and mechanical testing of joints. DGEBA and brominated DGEBA resins, and representative mixes of these were hydrolyzed in vitro. It is suggested that the major reaction at 40°C is polymerization, which is accelerated by moisture and leads to a crosslinked structure different to that resulting from normal cure. The poorer adhesive performance after aging is mainly the result of reduced resin flow during joint formation, although there is some contribution from the hydrolysis of epoxide groups which leads to lower crosslink density in the cured adhesive. The softening point of the uncured material and Tg of the cured material are useful indicators of the quality of this adhesive which, compared to some earlier formulations, has improved resistance to these conditions.
The radiation‐induced graft copolymerization of methacrylic acid with polyethylene. Ion‐exchange properties of the copolymeric composites
Authors: Guthrie J. T. , Kotov S.
Published: April 2003

The study involves the preparation and characterization of a series of polyethylene‐g‐comethacrylic acid polymers in which the comonomer provides a degree of hydrophilicity to the backbone polymer. Such copolymers have been shown to possess efficient ion‐exchange properties with respect to Fe(III) ions, used as a model for general exchange. As such, we have a useful extension to our work on enzyme immobilization and protein separations using this type of support. Grafting was carried out in air and under vacuum. A correlation between the carboxylic acid group content and the extent of grafting was found. Under the conditions employed in our experiments, a maximum in grafting levels was observed when water was used as a continuous medium but not when methanol was included in the solvent assembly. No significant difference was observed between grafting carried out in air and that carried out under vacuum, when aqueous solutions of methacrylic acid were used. The graft copolymers have been shown to be effective in isolating Fe(III) ions and to be amenable to recycling procedures.
Structural features of poly(alkylene ether carbonate) diol oligomers by capillary gas chromatography
Authors: Harris Robert F.
Published: April 2003

A series of poly(ethylene ether carbonate) diol oligomers were synthesized from ethylene carbonate (EC) using various catalysts and low EC:initiator molar ratios. The structures of these oligomers have been studied by alkaline degradation to the poly(ethylene glycol)s, which make up their backbone, followed by capillary gas chromatographic (CGC) analysis. Comparisons of CGC traces before and after hydrolysis indicate which volatile components contain carbonate moieties. Some poly(ethylene glycol)s were not chemically bound into the polymer backbone and were analyzed directly by CGC. Based on the combination of analytical techniques developed in this study, it is possible for the first time to establish the approximate composition of a given poly(ethylene ether carbonate) diol. A typical composition made using a sodium stannate trihydrate catalyst consists of (1) an oligomeric portion which is a copolymer of carbon dioxide and poly(ethylene glycol)s and (2) a monomeric portion which consists mostly of diethylene glycol with lesser quantities of monoethylene glycol, triethylene glycol, 1,4‐dioxane and unreacted ethylene carbonate.
Photochemical surface modification of poly(ethylene terephthalate)
Authors: Goldblatt Ronald D. , Park Jae M. , White Robert C. , Matienzo Luis J. , Huang Samuel J. , Johnson Julian F.
Published: April 2003

To elucidate the role of chemical interactions in the promotion of metal–polymer adhesion, a poly(ethylene terephalate)/copper system was studied. Surface photografting of unsaturated monomers containing different chemical functional groups onto a three‐mil poly(ethylene terephthalate) film provided a means of examining a variety of copper‐polymer interfaces. Initial graft verification was accomplished via contact angle measurements. Adhesion strengths to vacuum‐deposited copper were determined using 90° peel tests. Graft analysis, as well as investigation of the interfacial interaction between copper and the grafted moieties, was accomplished using X‐ray photoelectron spectroscopy.
Anionic polymerization of styrene: The search for an industrial process
Authors: Priddy Duane B. , Pirc Michael
Published: April 2003

Anionic polymerizations were carried out in the laboratory using a CSTR reactor design and conditions typical of current commercial mass polystyrene plants. Polystyrene having excellent color and polydispersity was produced. Polymer quality, styrene conversion, and molecular weight control were all linked to use of polymerization feed of consistently high purity and polymerization in the 90–110°C temperature range. The results of this study clearly show that high quality polystyrene can be made utilizing anionic polymerization chemistry in existing well mixed mass polystyrene reactors of the CSTR design. The key to the successful practice of this technology is the ability to produce consistently high purity polymerization feed.
Blends of imidized acrylic polymers with SAN copolymers and with PVC
Authors: Fowler M. E. , Paul D. R. , Cohen L. A. , Freed W. T.
Published: April 2003

A series of imidized acrylic polymers of varying structural composition generated by reaction of methylamine with poly(methyl methacrylate) were blended with a range of styrene/acrylonitrile or SAN copolymers (0–33% AN) and with poly(vinyl chloride). On the basis of glass transition behavior determined by differential scanning calorimetry, some but not all imidized acrylic structures were found to be miscible with PVC and with SAN copolymers within a limited window of AN levels. Acid functionality in the imidized acrylics appears to hinder their miscibility with SAN rather significantly and with PVC to a lesser extent. Miscible SAN blends showed lower critical solution temperature behavior whereas miscible blends with PVC did not up to the highest attainable temperatures. The composition factors that influence the phase behavior are described and interpreted in terms of possible mechanisms.
Studies on the synthesis of fiber‐forming block copolymers of polyacrylonitrile and poly(ethylene oxide)
Authors: Wódka Tadeusz
Published: April 2003

Modified PEO (MW 6000) containing xanthate groups was used for the synthesis of block copolymers of PAN and PEO. Principal parameters affecting the synthesis 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. The fiber‐forming properties were investigated by means of rheological examination of concentrated solutions of PAN–PEO and confirmed by spinning the fibers under laboratory conditions. The physical and mechanical properties of the fibers were also determined.
The lithographic effect of electron beam on poly(methyl methacrylate) in a scanning electron microscope: Minimization of line width by the dose and beam current
Authors: Muchová M. , Pelzbauer Z.
Published: April 2003

The lithographic effect of electron beam in line exposures in scanning electron microscopy (SEM) on poly(methyl methacrylate) (PMMA) was evaluated using the line width in a film deposited on a silicium substrate and from the line profiles in a PMMA plate. It was found that the effect of the dose on dimensions of the exposed structures in line exposures is not unambiguous, in contrast to area exposures, but that at constant dose and beam width the line dimensions increase with beam current. Sensitivity in line exposures (line sensitivity) is smaller than in area exposures (area sensitivity). The effect of beam current on the line width increases with decreasing dose; at doses close to line sensitivity it is the strongest. The increasing effect of a beam on the polymer with increasing current at constant dose is explained through the increasing range of thermal degradation due to exposure. A qualitative explanation is based on simplified calculations of the thermal conditions in the resist film during and after the exposure.
Wilkinson's salt: A flame retardant for poly(methyl methacrylate)
Authors: Sirdesai Sunil J. , Wilkie Charles A.
Published: April 2003

Poly(methyl methacrylate) reacts with RhCI(PPh3)3 at 260°C in a sealed tube to produce a material which is insoluble in common solvents. The infrared spectrum and CP/MAS 13C‐NMR spectrum indicate the presence of anhydrides. Differential scanning calorimetry shows that the transition temperature has increased by 15°C. Thermogravimetric analysis indicates that 25% of the material is not volatilized at 600°C. The oxygen index of the mixture of the rhodium compound with PMMA increases from 14 to 20 (bottom ignition).
Sorption of organic liquids and vapors by rigid PVC
Authors: Berens Alan R.
Published: April 2003

The effects of activity and solvent strength of a number of organic penetrants upon their sorption kinetics and equilibria in poly(vinyl chloride) have been studied by gravimetric vapor and liquid sorption experiments at 30°C. For each solvent, the relation of equilibrium sorption to activity is well approximated by the Flory–Huggins equation with a characteristic value of the interaction parameter χ. The glass transition temperature Tg is depressed in direct proportion to the volume fraction of solvent absorbed; the composition corresponding to a Tg of 30°C, Cg (30°C), is in the range of 0.22–0.30 volume fraction for several common solvents. The form of the sorption kinetics varies with the ratio of the equilibrium sorption to Cg, and thus depends on the combined effects of χ, solvent activity, and plasticizing action. When the equilibrium sorption is less than about Cg/2, kinetics are Fickian, with the very low diffusivities typical of the glassy state; for sorption values between Cg/2 and Cg, anomalous kinetics are observed; and when the sorption is greater than Cg, transport in thin PVC films follows Case II kinetics. At high sorption levels, increasing film thickness produces a shift of the kinetics toward Fickian form with apparent diffusivity values typical of rubbery polymers.
Microporous clay membrance materials for reverse osmosis applications. I. Performance characteristics from osmotic studies
Authors: Adhikari M. , Ghosh S. K.
Published: April 2003

Fired clay membranes were prepared from montmorillonite clay and also by incorporating protein (lysozyme) and nylon (copolymer of 6‐amino caproic acid) to clay followed by firing these membranes at different temperatures for different durations of time. Osmotic behaviors of the membranes were studied, and the results were correlated to the porosity determined by scanning electron microscope. Reverse osmosis parameters, namely, the reflection coefficient, solute permeability, and rejection coefficient, of the membranes were determined from osmosis experiments. Rejection coefficients as determined from reverse osmosis were compared with those obtained from osmosis experiments.
The crystallization and transition behavior of poly(vinylidene fluoride)/copoly(chlorotriofluorethylene‐vinylidene fluoride) blends
Authors: Siegmann A. , Cohen G. , Baraam Z.
Published: April 2003

Thermal analysis of solution precipitated blends of two crystallizable polymers, poly(vinylidene fluoride) (PVDF) and copoly(chlorotrifluorethylene‐vinylidene fluoride) (copoly(CTFE‐VDF)), has been carried out to study the transition temperatures, crystallinity, and crystallization rates. PVDF crystallizes over the whole blend composition either during precipitation from solution or upon cooling from the melt. The high degree of crystallinity attained, higher than in PVDF by itself, suggests the occurrence of partial PVDF‐copolymer cocrystallization. The melt crystallization temperature, decreasing with cooling rate, is lower in PVDF‐rich blends than for lean blends. However, the heat of crystallization increases with cooling rate, suggesting that the crystal composition depends on crystallization rate. No significant melting temperature depression due to blending was observed. However, the blends glass transition (Tg) changes linearly with composition, but less than expected by any mixing rule applicable to compatible systems. Annealing of the blends above Tg results in an additional crystalline phase consisting mainly of the copolymer. The amount of these crystals increases with PVDF content, due to partial cocrystallization and kinetic effects. The addition of the copolymer to PVDF results in a volume‐filling spherulitic structure consisting of spherulites which decrease in size with increasing copolymer content.
Impact thermoplastics: Combined role of rubbery phase volume and particle size on toughening efficiency
Authors: Cigna G. , Lomellini P. , Merlotti M.
Published: April 2003

A relationship has been found for OSA (olefin‐acrylonitrile‐styrene) polymers between normalized Izod impact strength (ΔI/N) or yield stress (Δσy/N) with mean particle radius. These normalized functions (which analytically include radius and rubbery phase volume) are representative of the toughening effect of a single particle with respect to the styrene‐acrylonitrile (SAN) rigid matrix. ΔI/N and Δσy/N increase exponentially as a function of the radius. This approach, for Izod, was also applied to HIPS and toughened nylon reported in the literature and similar results were obtained. In the case of nylon, however, the ΔI/N values are split in two different curves related to the tough‐brittle transition described in that literature. Referring to OSA, three samples (with the largest radii more than 0.22 μm) fail in a brittle manner and do not fit the curve of ΔI/N: they fit, however, that of Δσy/N. Further work must be done in order to investigate a decisive role either of interfacial adhesion (eventual lack for these three materials) or of tough‐brittle transition mentioned before for shear‐yielding deforming materials. In fact, OSA has behavior intermediate between that of nylon and HIPS which deforms by crazing.
The crystallization of a copoly(chlorotrifluorethylene‐vinylidene fluoride) from the amorphous rubbery state
Authors: Siegmann A. , Cohen G. , Baraam Z.
Published: April 2003

A random copoly(chlorotrifluorethylene‐vinylidene fluoride) in the ratio of 3 : 1 was annealed at the temperature range of Tg < T < Tm. The copolymer slowly crystallizes, attaining a rather low ultimate degree of crystallinity, depending on the annealing temperature, in the form of randomly distributed ribbonlike lamellae. The crystallites' melting temperatures are much lower than those of the corresponding homopolymers, increasing with annealing temperature and time. The crystallization kinetics, analyzed using the Avrami equation, indicates the formation of small, low‐ordered crystallites. The crystallization process results in a dramatic increase in the elastic modulus at T > Tg. Annealing of stretched samples results in oriented crystallization at much higher rates than in the unstretched material, without markedly affecting the ultimate degree of crystallinity. The oriented crystallites, distributed in an isotropic amorphous matrix, exhibit lower thermal stability than the corresponding unoriented crystals. Their melting temperatures increase with annealing time; however, they decrease with the extent of stretching, suggesting a strong kinetic effect on the crystallites' degree of order.
Investigations on the curing of epoxy resins with hexahydrophthalic anhydride
Authors: Steinmann Bettina
Published: April 2003

The bifunctional epoxides bisphenol A diglycidyl ether (BADGE) and hexahydrophthalic diglycidyl ester (HHDGE) as well as the monoepoxides phenyl glycidyl ether (PGE) and cyclohexane carboxylic acid glycidyl ester (CHGE) were cured with hexahydrophthalic anhydride (HHPA) in the presence of benzyldimethylamine (BDMA) or 1‐methylimidazole (1‐MI) as catalysts at 100–140°C. Investigations of the curing kinetics gave sigmoidal‐shaped curves with marked induction periods. IR analysis of the cured products revealed that the propagation proceeds not only by the esterification reaction of epoxide with anhydride but also by chain anhydride formation by the reaction of carboxylate with anhydride groups. 13C‐NMR investigations of the soluble polymers showed that most of the peaks resulting from double bonds could not be assigned to structures formed by initiation reactions that had previously been proposed for the anhydride curing of epoxides. In analogy to a postulated mechanism for the decarboxylation condensation of HHPA alone in the presence of tertiary amines, it is proposed that an isomerization product of HHPA is one of the molecules that initiate the curing reaction.
An approximate method for the determination of polymer–polymer interaction parameters of incompatible polymers in solution
Authors: Narasimhan Venkataraman , Huang Robert Y. M. , Burns Charles M.
Published: April 2003

A method is developed, based on Scott's equations for ternary systems of two polymers and a mutual solvent, for the calculation of values of the polymer–polymer interaction parameter, χ23, for systems in which both polymer–solvent interaction parameters χ12 and χ13 are not known a priori. Equilibrium phase studies were carried out on ternary systems of polystyrene, polybutadiene, and tetrahydrofuran or toluene at 23°C and 1 atm. Typical interaction parameter values (χ23) calculated by this new method were compared with the values of χ23 determined earlier using standard equations and known χ12 values for these systems, and were found to agree very well. It is concluded that the technique presented in this article can be used for mixed polymer systems in good mutual solvents where neither polymer–solvent interaction parameter is known, for determining an approximate value of the χ23 parameter alone.
Network structure and properties of imidazole‐cured epoxy novolac adhesives
Authors: Madsen Patricia A. , Foister Robert T.
Published: April 2003

The structural characteristics of four epoxy adhesives, obtained by crosslinking an epoxy novolac with various levels of a substituted imidazole curing agent, were investigated and correlated with thermal and mechanical properties. Variations in network structure were characterized by measuring crosslink densities and by qualitatively assessing glassy state free volume from densities and coefficients of thermal expansion. Differential scanning calorimetry was used to obtain glass transition temperatures, and dynamic mechanical thermal analysis was used to follow primary (alpha) and secondary (beta) transitions. Bulk behavior was characterized by tensile modulus, strength, and toughness, together with compressive modulus and yield strength. The effect of sub‐Tg aging on compressive yield strength was investigated as well. As the level of imidazole increased, crosslink density, and hence network packing efficiency and free volume, decreased. For fully cured networks, both the glass and the alpha transition temperatures increased with crosslink density. Calculated activation enthalpies and entropies indicated significant degrees of network cooperativity in the alpha transitions, particularly for the more highly crosslinked systems. Beta transition temperatures, however, were found to be independent of crosslink density. Bulk properties generally showed a dependence both on crosslink density and free volume. Yield stress, for example, was highest for the network with lowest crosslink density and free volume. Volume relaxation associated with physical aging also caused yield stress to increase.
Porous substances immobilizing enzymes with polymer matrix
Authors: Kumakura Minoru , Kaetsu Isao
Published: April 2003

The preparation of porous substances immobilizing enzymes with polymer matrix having various properties have been studied by radiation polymerization method. The enzyme (cellulase) was immobilized on the surface parts of porous substances such as activated carbon, molecular sieve, silica gel, and coating with hydrophilic and hydrophobic monomers. As substrate of enzyme reaction, lignocellulosic wastes such as chaff pretreated by radiation irradiation (100 Mrad) were used. The enzyme activity of the immobilized enzyme substances was markedly affected by hydrophilicity of monomer and the copolymerization of methoxypoly(ethyle glycol) methacrylate (75%) and poly(ethylene glycol) dimethacrylate (25%) monomer gave the most highest enzyme activity. The immobilized enzyme substances was able to hydrolyze chaff pretreated by radiation irradiation.
Sorption behavior of water vapor into polyelectrolyte complex of poly(acrylic acid)/poly(4‐vinylpyridine)
Authors: Hirai Yoshiyuki , Nakajima Toshinari
Published: April 2003

The sorption of water vapor into the polyelectrolyte complex of poly(acrylic acid)/poly(4‐vinylpyridine) has been investigated. The sorption isotherm was evaluated on the basis of various theories; BET equation, Flory–Huggins interaction parameter χ1, and cluster function G11/v1. The behavior of the BET plot, χ1, and G11/v1 was considered in terms of the structure of the complex, while the crosslink density and charge density were determined from the carbonyl absorption in IR spectra. The reasonable conclusion drawn from the available data is as follows. The interaction of water with specific polymer sites plays an important role in the sorption. The sorbed water plasticizes this material, and it enables the expansion of the network. The large amounts of water incorporated by the expansion cannot be dispersed homogeneously in the network, and indicate clustering tendency.
Dynamic‐mechanical relaxations in high and low density polyethylenes. Effects of irradiation and annealing
Authors: Greus Amparo Ribes , Calleja Richardo Diaz
Published: April 2003

A study of the dynamic‐mechanical relaxation spectrum in a series of commercial high and low density polyethylenes (Dow Chemical), irradiated as well as unirradiated, and subjected to different annealing process, has been performed. The effect of 20‐Mrad dose of irradiation on the chemical structure has been analyzed and an increase in the number of aldehyde, ketone, and transvinylene groups and a decrease in the number of vinyl and vinylidene groups has been observed. The dynamic‐mechanical spectrum of irradiated and unirradiated high and low density polyethylenes contains the γII‐, γI‐, β‐, αI‐, αII‐, and αIII‐ relaxations, in order of increasing temperature. It has been observed that γ‐irradiation followed by annealing modified the intensity and the position of relaxations in these polyethylenes.
Rubber‐modified epoxies: Interfacial tension and morphology
Authors: Sohn John E. , Emerson John A. , Thompson Patrick A. , Koberstein Jeffrey T.
Published: April 2003

The interfacial tension between carbomethoxy‐terminated butadiene–acrylonitrile copolymers and an epoxy resin as a function of temperature and copolymer composition is investigated. Using a digital image processing technique, the shape of a pendant drop of the epoxy in the copolymer is determined. Analysis of the drop shape is performed by profile discrimination and subsequent robust shape analysis. The data are used to examine the relationship between interfacial tension and particle size of the dispersed copolymer‐rich phase in rubber‐modified epoxy resins, that are immiscible in the uncured state.
The thermal shrinkage of the drawing poly(ethylene isophthalate terephthalate) copolyester films
Authors: Hsiue Ging‐Ho , Yeh Tuu‐Sheng , Chang Shuya
Published: April 2003

The objective of this study is to use the copolymerization method to improve the thermal shrinkage property of poly(ethylene terephthalate) (PET), so that the resultant copolyester can be used for the application of thermal shrinkage packing materials. The poly(ethylene isophthalate terephthalate) (PEIT) copolyester films were prepared and studied. The thermal shrinkage rate of PET films and the thermal shrinkage rate of the copolyester films were measured by using a thermomechanical analyzer (TMA). The thermal shrinkage of copolyester was found to be dependent on such factors as composition, molecular weight, and draw temperature. The highest thermal shrinkage was obtained when the copolymer contained 40 mol % of ethylene isophthalate. Its shrinkage ratio and shrinkage rate were consistently 1.3 and 2.4 times those of PET. The increase of molecular weight and decrease of drawing temperature resulted in the increase of the thermal shrinkage. The best drawing temperature range was between glass transition temperature and soft temperature of the copolymer. The relationship of shrinkage rate and temperature indicate that the shrinkage mechanism of the copolyester belongs to two‐step thermal shrinkage.
Polymer–filler interactions in hydroxy‐terminated polybutadiene–ammonium perchlorate system in the presence of a bonding agent
Authors: Kishore Kaushal , Rajalingam Ponswamy
Published: April 2003

Bonding between ammonium perchlorate (AP) and hydroxy‐terminated polybutadiene (HTPB), constituting a nonreinforcing filler system, has been studied in the presence of a unique bonding agent (BA)–a switter ion molecule, 2,4‐dinitrophenylhydrazone derivative of 1,1′‐bisacetylferrocene (DNPHD AF). Extensive conjugation and a permanent ionic character makes the DNPHD AF to bond strongly with the ionic oxidizer AP. Through its terminal OH group, HTPH bonds with the NO2 groups of DNPHD AF. Bonding sites in the molecules have been located from IR studies and from the first‐order rate constant measurements of the bonding of DNPHD AF and other model BAs with HTPB and AP. The bonding ability of DNPHD AF is further evidenced from SEM micrographs.
Fluorescence polarization study of the curing process of epoxide with aminimide
Authors: Ikeda Tomiki , Inubushi Shinzo , Tazuke Shigeo
Published: April 2003

The curing process of epoxide (Epikote 828, EK) with aminimide (trimethylamine valerimide, TMAV) was studied by a fluorescence polarization method. Two types of probe molecules were used: One was perylene (PE), which was just physically incorporated into the curing mixture and termed as the “extrinsic” probe, and the other was fluorescent product(s) formed during curing of EK with TMAV, which was termed as the “intrinsic” probe. Extraction experiments revealed that the “intrinsic” probe was covalently incorporated into the crosslinked matrix. No emission was observed for the “intrinsic” probe before heating, but its intensity increased with curing at 150°C. Fluorescence anisotropy (r) of both EK/TMAV/PE and EK/TMAV systems increased monotonically with curing time at the initial stage and then remained nearly constant. This means that at the early stage of curing the network becomes rigid enough to restrict rotational diffusion of the probe molecules. Calculated r values for the “extrinsic” probe alone were lower than observed r values of the “intrinsic” probe, which was well explained in terms of the mode of incorporation of the two types of the probe molecules into the matrix.
Graft copolymerization with a new class of acidic peroxo salts as initiator. V. Grafting of methyl methacrylate onto jute fiber using potassium monopersulfate catalyzed by Fe(II)
Authors: Samal Rajani K. , Samantaray Himansu S. , Samal Rabi N.
Published: April 2003

Graft copolymerization of methyl methacrylate (MMA) onto jute fibers was studied in an aqueous solution using a new class of acidic peroxo salt, potassium monopersulfate, as initiator, under the catalytic influence of Fe(II) under nitrogen atmosphere. The grafting reaction was influenced by the reaction time, temperature, and concentrations of monomer, initiator, and jute fibers. The grafting reactions have also been studied in the presence of various salts and solvents. The maximum grafting percent (385.4%) has been observed at 35°C for the concentration of monomer (1.4082M), initiator (12.9 × 10−3M), catalyst (2.5 × 10−4M), and solvent (acetic acid) composition of (40:60) for a reaction time of 6 h. From the experimental results a suitable mechanism for the graft initiation and termination has been put forth. The graft copolymers have been characterized, and their improved properties such as tensil strength tested.
Engineering plastics from lignin. XVI. Starlike macromers with propylene oxide
Authors: Oliveira Willer De , Glasser Wolfgang G.
Published: April 2003

Starlike macromers were prepared from hydroxypropyl organosolv lignin by reaction with propylene oxide, and they were analyzed by a combination of conventional analysis techniques. The average number of arms per macromer was controlled by partial capping with an alkoxy group; and the average length of arms by the degree of chain extension with propylene oxide. Analysis methods included treatment with hydriodic acid followed by gas chromatographic separation of alkyl iodides (HI/GC), UV spectroscopy, H‐NMR spectroscopy, and thermal analysis. The results were consistent with a hypothetical pentameric model structure having between two and six radiating arms, each with a length of between 1 and 4 propylene oxide units. The UV method was best qualified to determine degree of chain extension, while HI/GC was best suited for analyzing average number of arms per macromer fragment. The synthesis and analysis of starlike macromers from lignin is viewed as an important stepping stone for the formulation of lignin‐based engineering plastics and multiphase materials.
Separation of stat‐copoly(styrene/2‐methoxyethyl methacrylate) samples according to composition by gradient high‐performance liquid chromatography
Authors: Glöckner Gottfried , Stickler Manfred , Wunderlich Winfried
Published: April 2003

Statistical copolymers of styrene (S) and 2‐methoxyethyl methacrylate (MEMA) (13–87 mass % of the latter monomer) were investigated by gradient HPLC on columns with either silica or CN‐bonded phase packings. The samples were injected in THF solution. The starting eluent was in each case a nonsolvent (isooctane or mixtures of isooctane with THF and methanol). Separation was achieved by increasing the concentration of THF or methanol in the eluent. A calibration mixture of four copolymers (26, 49, 62, and 87% MEMA) was investigated according to the principles of chromatographic cross‐fractionation (CCF) by size exclusion chromatography and subsequent gradient HPLC. The influence of molar mass on HPLC retention was small and, for the samples investigated by CCF, independent of copolymer composition. The composition effect on detector signal was also studied. At 230 nm wavelength and with MEMA content in the range between 20 and 40%, the effect was small and caused the average composition calculated from CCF results to deviate from the directly measured value by not more than 0.2 or 0.8% for the two copolymers investigated.
Effect of tetrabromobisphenol A diallyl ether on the flame retardancy of high impact‐strength polystyrene
Authors: Yang Chin‐Ping , Sheen Biing‐Shiow
Published: April 2003

The effect of tetrabromobisphenol A diallyl ether (TBBA–DAE) on the flame retardancy of high impact‐strength polystyrene (HIPS) was studied and compared with that of tetrabromobisphenol A (TBBA). Experimental results showed that the flame retardancy of TBBA–DAE was superior to that of TBA by thermomixing in the solid state. However, this phenomenon was not obvious by mixing in solution. This effect might result from the bromination of HIPS by the modified Claisen rearrangement of TBBA–DAE during thermomixing in the solid state. Simultaneous addition of the mixture of TBBA–DAE or TBBA with diphenyl isooctylphosphite (DPIOP) into HIPS caused a synergistic effect of flame retardancy and the effect of TBBA‐DAE was better than that of TBBA.
Differential scanning calorimetry study on intermolecular interactions in polymer–diluent blends involving polyisoprenes and dimethyl terephthalate
Authors: Ng S. C. , Chee K. K.
Published: April 2003

The classical expression for estimating the polymer‐solvent interaction parameter χ from melting point data of the solvent is refined by considering χ to be concentration‐dependent. Differential scanning calorimetry (DSC) measurements are performed on blends of cis‐polyiso‐prene‐dimethyl terephthalate (DMT) and trans‐polyisoprene–DMT. It is found that the presence of DMT would not affect the DSC events of the polyisoprenes appreciably. However, in both cases, the melting point of DMT decreases, and the rate of depression increases with increasing proportions of polymer. These DSC data are analyzed by the proposed procedure. The results on the interaction energy density parameter are presented as a function of the blend concentration, and rationalized by the specific interactions between different moieties on the component molecules. The limitations of the present technique are discussed.
Methylcentralite concentration profiles in monoperforated extruded nitrocellulose and nitrocellulose/nitroglycerine propellant grains by Raman microspectroscopy
Authors: Louden J. D. , Kelly J. , Phillipson J.
Published: April 2003

Raman microscopy was used to determine the methylcentralite (MC) concentration profiles diffused into single‐base (nitrocellulose) (NC) and double‐based (nitrocellulose/nitroglycerine) (NC/NG) small‐arms propellant grains. External and internal concentration profiles were determined by measuring the concentration of MC relative to the NC and NC/NG at 5‐μm intervals into the grain from the edge inward and the perforation edge outward. The external profile was constant with a diffusion and interaction mechanism, i.e., a level concentration of deterrent through the outer region of the grain followed by a gradual dropoff in concentration with distance into the grains, whereas the internal profile was found to be dependent on perforation size with either a diffusion and interaction mechanism profile or a gradual decrease in concentration profile.
Ionomers: The sodium salt of poly(ethylene‐co‐methacrylic acid)
Authors: Han Keling , Williams H. Leverne
Published: April 2003

A chemical method and an improved absorbance ratio method are presented to determine the degree of neutralization of poly(ethylene‐co‐methacrylic acid). Compared to the chemical method, the absorbance ratio method is simple and fast. It can be used also to determine the degree of neutralization when the chemical method is not suited to the system. By means of this absorbance ratio method, the influences of various reaction conditions on the rates of neutralization were observed. In the neutral system at the optimal water content a maximal rate of neutralization is obtained. The rate of neutralization is increased by increasing the temperature or the concentration of metal hydroxide or by decreasing the concentration of the copolymer.
Proton‐NMR studies of polyacetal copolymers
Authors: Ogawa Toshio , Ishitobi Wataru , Jinta Kazuya
Published: April 2003

Sequence length of ethylene oxide and the amount of end groups in polyacetal copolymers were determined using proton NMR. Peaks from ethylene oxide usually appear in the region from 3.5 to 3.8 ppm, when tetramethylsilane was used as the internal standard. These peaks were divided into three triad sequences, i.e., MEM, MEE, EEE (E = ethylene oxide, M = methylene oxide) by referring to several polymers of similar structure. The sequence length in a copolymer prepared from ethylene oxide was 1.37 and that from trioxocan was 2.00. Small peaks from end groups usually appear in the region higher than 3.5 ppm. The peaks from methoxy and ethoxy groups were easily detected and determined quantitatively. The peak from hydroxy groups was detected after acetylation of a copolymer, because the original sample did not give a distinct peak corresponding to that group. The number‐average molecular weight of the copolymer prepared from trioxocane was estimated from the content of methoxy, ethoxy, and hydroxy groups. The value thus obtained was consistent with that obtained by gel permeation chromatography.
Free‐radical transport from latex particles
Authors: Mead R. N. , Poehlein G. W.
Published: April 2003

A rate constant for the diffusion of monomer radicals from latex particles is derived using the transport equations describing the generation, diffusion, and reaction of monomer radicals within the particles. Calculations for styrene emulsion polymerization show that this “desorption constant” accounts for nonuniform distribution of monomer radicals within the particle while some previously published theories do not. The difference in the desorption constant calculated with the model derived in this work and the “uniform concentration” models could be an order of magnitude when diffusivity of monomer radicals in the particles is small. The monomer radical transport theory is extended to emulsion copolymerization. Desorption rate constants accounting for nonuniform distribution of monomer radicals are derived for emulsion copolymerization.
Infrared attenuated total reflectance study of latex paint films exposed to aqueous sulfur dioxide
Authors: Xu J. R. , Balik C. M.
Published: April 2003

Fourier‐transform infrared/attenuated total reflectance (FTIR–ATR) has been used to investigate the effects of acidic deposition on latex paint films with and without a calcium carbonate extender additive. Paint films approximately 5 mils thick were exposed to aqueous SO2(pH 2.0) for various times by simple immersion. Rapid and complete removal of CaCO3 from the paint film was found to occur, and the kinetics of the removal process were monitored using both weight loss and FTIR–ATR measurements. Both methods revealed Fickian diffusion, with an apparent diffusion coefficient D = 1.84 × 10−9 cm2/s. Good agreement was obtained between D measured via FTIR–ATR and from the weight lost data. The mechanism of removal of CaCO3 from the latex paint films appears to be controlled by the rate at which water and other components of the aqueous SO2 solution can diffuse into the film.
Preparation of latex carriers for controlled release by concentrated emulsion polymerization
Authors: Kim Kyu‐Jun , Ruckenstein Eli
Published: April 2003

Spherical latexes of submicron diameter containing a model hydrophobic herbicide, namely, 2‐(2,4‐dichlorophenoxy)‐propionic acid, were prepared by the concentrated emulsion polymerization method. A mixture of styrene, herbicide, and initiator was dispersed into a small amount of water (6% by volume based on the entire emulsion) containing surfactant, at room temperature. The heating at 40°C of the foam like gel thus obtained led to the formation of latexes containing the herbicide. It was found that the model herbicide dispersed in the polymer latex was released to water over a period of serveral weeks and that the amount released was strongly dependent upon temperature and latex concentration in water.