bluuebunny/crossref_metadata_2025 huggingface dataset:
Allylamine‐adducted bismaleimide resins. I. The curing reactions
Authors: Lin King‐Fu , Lin Jin‐Sing
Published: April 2003

A variety of allylamine‐adducted bismaleimide (A‐BMI) resins were prepared by reacting bismaleimide (BMI), such as 4,4′‐bismaleimidodiphenylmethane (BDM) and 4,4′‐bismaleimidodiphenylether (BDE), with various molar ratio of allylamine through the Michael addition. The prepared A‐BMI resins are a partial crystalline or completely amorphous solid, depending on the amount of adducted allylamine. Two types of curing reactions for the A‐BMI resins were detected by differential scanning calormetry and verified by the mass spectroscopies of cured resins: one is the homopolymerization of A‐BMI resins through opening of the double bonds in the maleimide groups; the other is the reactions between allyl groups and benzene rings, taking place mainly when most of the double bonds in maleimide groups of the A‐BMI resins have been opened by allylamines. © 1993 John Wiley & Sons, Inc.
Effects of fluorinated substituents on the refractive index and optical radiation resistance of methacrylates
Authors: Gaynor Justin , Schueneman Gregory , Schuman Paul , Harmon Julie P.
Published: April 2003

Novel fluorinated methacrylate polymers were synthesized. The purpose was to produce polymers with low refractive indices and increased resistance to optical radiation damage. Six different fluorinated substituents were appended on the monomer before polymerization. Optical‐quality samples were prepared, and their transmission spectra, through 0.8 cm thick samples, were obtained. Each sample was tested for refractive index and glass transition temperature. The samples absorbed 10 MRad gamma radiation from a 60Co source in an air environment; their transmission spectra were recorded immediately after irradiation and again after seven days had elapsed. As expected, increasing the fluorine content in the side chains resulted in decreased refractive indices. Fluorine content also influenced optical radiation stability. One polymer, poly(1H,1H‐heptafluorobutyl methacrylate) retained superior UV/visible transmission after irradiation. © 1993 John Wiley & Sons, Inc.
Comparative study of unsaturated halo and nonhalo polyesters and inhibition of double‐base rocket propellants
Authors: Agrawal J. P. , Kulkarni K. S.
Published: April 2003

Unsaturated halo and nonhalo polyesters, based on tetrachlorophthalic anhydride, tetrabromophthalic anhydride, and phthalic anhydride with diethylene glycol and maleic anhydride, have been synthesized, using a “2‐step” polyesterification process. These were mixed with 35% styrene monomer and 0.02% hydroquinone. The structural aspects of halo and nonhalo polyesters have been studied by IR and NMR. Further, these polyesters have been characterized for various properties. A comparison of various properties suggests that tensile strength, bond strength, heat resistance, flame retardance, gel time, and oxygen index follow the order as BP‐35 > CP‐35 > NHP‐35, whereas the order for other properties, such as exotherm peak temperature, thermal conductivity, % elongation, and nitroglycerine absorption, is BP‐35 < CP‐35 < NHP‐35. Variation in the properties of cured halo and nonhalo polyesters has been discussed in terms of structural considerations. The nature of P‐t profile of inhibited double‐base (DB) rocket propellants on static evaluation suggests that CP‐35 is a potential inhibitor for DB propellants. © 1993 John Wiley & Sons, Inc.
Adiabatic anionic polymerization of caprolactam in the presence of N‐acylated caprolactam macroactivator: Kinetic study
Authors: Yeh Jen‐Long , Kuo Jen‐Feng , Chen Chuh‐Yung
Published: April 2003

In this study, bis ϵ‐caprolactam bis‐diphenyl methane diisocyanate polypropylene glycol 1000 used as the macroactivator was prepared and well characterized prior to use. The anionic polymerization of ϵ‐caprolactam with the macroactivator as a function of the macroactivator concentration was adiabatically carried out. The adiabatic temperature rise method as well as the macrokinetics were used for elucidation of the kinetics of the polymerization. A nonlinear regression technique was used for determining the parameters of the macrokinetic equation. The equilibrium conversion and equilibrium time obtained were 94–96% and 2–9 min depending on the macroactivator concentration. The effects of the concentrations of macroactivator and ϵ‐caprolactam on the initial rate, apparent overall reaction rate, and the empirical parameters were studied. A side reaction induced by the transfer of the proton in the isocyanurate group of the macroactivator to caprolactam anion was found. According to this finding, a new reaction kinetic model was proposed by properly modifying the macrokinetic equation. © 1993 John Wiley & Sons, Inc.
Cathodic delaminations of poly(phenyl ether ether ketone) (PEEK) coatings overlaid on zinc phosphate‐deposited steels
Authors: Sugama T. , Carciello N. R.
Published: April 2003

The melt‐crystallized poly(phenyl ether ether ketone) (PEEK) polymer was overlaid on crystalline zinc phosphate (Zn • Ph) conversion coating‐deposited and nondeposited coldrolled steels at 400°C in air or in N2 environments. The ability of these coating systems to protect the steel against corrosion was evaluated from the rate of cathodic delamination of the coating layer from the steel. Because the cathodic reaction, H2O + 1/2O2 + 2e− = 2OH−, at the corrosion side of a defect in the coating layer creates a high pH environment at the interfacial boundary between the coating and steel, the magnitude of susceptibility of the interfacial intermediate layers to the alkali‐induced degradation played a key role in suppressing cathodic failure. The lowest level was observed in the N2‐induced PEEK/Zn • Ph/steel joint systems, thereby decreasing the rate of delamination. By contrast, oxidized PEEK induced by air in same joint systems was susceptible to the alkali‐catalyzed hydrolysis. This phenomenon significantly promoted the alkali dissolution of Zn • Ph crystals, reflecting a high rate of delamination. Nevertheless, the introduction of Zn • Ph as interfacial tailoring material into the intermediate layers markedly acted in reducing the cathodic delamination of PEEK/steel joint systems. © 1993 John Wiley & Sons, Inc.
Study of the electric‐field effect in polyethylene by the positron annihilation technique
Authors: El‐Sayed A. M. A. , Abdel‐Hady E. E. , Mohsen M.
Published: April 2003

The positronium formation and the reversibility behavior of the electric field from 31.75 to 588.24 kV/cm were studied in high‐density polyethylene (HDPE) using the positron annihilation lifetime technique. The lifetime measurements were performed using the conventional fast‐fast coincidence timing system. The observed ortho‐positronium life time τ3 does not show significant variation from the corresponding values measured without the electric field. On the other hand, the corresponding intensity I3 increases with increasing the electric field strength in the range from ∼ 100 to 588.24 kV/cm. This result indicates a strong irreversible effect of the electric field. In addition, the effect of temperature on the sample stressed at 450 kV/cm was investigated. The structural changes on the heating and cooling cycles show reversible behavior. The thermal expansion coefficient has been deduced to be 7.53 × 10−3/°C. © 1993 John Wiley & Sons, Inc.
NG‐migration into double‐base inhibitors. I. Sorption
Authors: Potgieter H. F. , Sanderson R. D.
Published: April 2003

Double‐base propellants are inhibited with polymeric material to restrict the burning surface. The energetic plasticizer may migrate out of the propellant into the inhibitor. This may then cause the inhibitor to deteriorate. Thus, the measurement of the amount of energetic plasticizer that migrates into the inhibitors is important.

Sorption measurements are done using a “sandwich” test. The data obtained are used in an empirical formula to calculate the maximum amount of energetic plasticizer that will be absorbed by a particular polymer. The validity of the formula is confirmed. © 1993 John Wiley & Sons, Inc.
Wet spinning of chitosan and the acetylation of chitosan fibers
Authors: East George C. , Qin Yimin
Published: April 2003

Chitosan fibers were made by wet spinning of its solution in 2% aqueous acetic acid. The fiber properties were affected by processing conditions, such as spin stretch ratio, coagulation bath composition, and drying conditions. The chitosan fibers were acetylated with acetic anhydride in methanol, producing regenerated chitin fibers. The acetylation process was affected by the reaction temperature, the treatment time, and the molar ratio of anhydride to amine groups. The properties of the acetylated chitosan fibers were studied in terms of thermal stability, solubility, and mechanical properties. It was found that, after acetylation, the fibers had an improved thermal stability and tensile strength. © 1993 John Wiley & Sons, Inc.
Equation of state predictions of sorption isotherms in polymeric materials
Authors: Hariharan R. , Freeman B. D. , Carbonell R. G. , Sarti G. C.
Published: April 2003

The ability of the Sanchez‐Lacombe equation of state to predict the solubility of small penetrants in rubbery polymer matrices, over a wide range of ambient pressures, is examined critically. The solute chemical potential and, in turn, the resulting predicted isotherms are found to depend strongly on solute equation of state parameter values and on the mixing parameter for polymer‐penetrant interactions. The isotherms are less sensitive to polymer equation of state parameters. In the sorption of organic vapors into polymers, the model does not describe well the sorption isotherms at high values of penetrant activity. The model appears to describe sorption isotherms most accurately when both polymer and penetrant equation of state parameters are determined from pure component properties, in the same temperature and pressure range as the sorption data, and when a mixing parameter is used to adjust the fit of the model to the data. © 1993 John Wiley & Sons, Inc.
Mechanisms of antioxidant action: Nature of transformation products of dithiophosphates. Part III. The antioxidant action of dithio and thio/thionophosphoric acids
Authors: Al‐Malaika S. , Coker M. , Scott G. , Smith P.
Published: April 2003

The nature of transformation products of dithio‐ and thionophosphoric acids in the presence and absence of hydroperoxides and their role as transformation products formed during oxidation of thiophosphoryl disulfide at high temperatures is investigated. The major transformation product of dithiophosphoric acid was found to be the corresponding disulfide while thiophosphoric acid was the major oxidation product of the reaction of thionophosphoric acid with hydroperoxide. In the case of thiophosphoryl disulfide, it is shown that thionophosphoric acid was found to be one of the major transformation products in the presence of hydroperoxides, whereas no acids were formed in the absence of added hydroperoxides. © 1993 John Wiley & Sons, Inc.
Solubility of binary liquid mixtures in polymeric materials
Authors: Vahdat Nader
Published: April 2003

Experimental data on the permeation of binary mixtures through polymeric materials show that liquid mixtures can exhibit large, positive synergistic rates. As the permeation rate depends on both solubility and the diffusion coefficient, the existence of a maximum in the steady‐state permeation rate vs. the composition curve could be due to an increase in solubility and/or diffusion coefficient. In this study, a theoretical model based on the Flory‐Huggins equation was developed to predict the solubility of binary liquid mixtures in polymers. The equation has four adjustable parameters that can be determined from solubilities of pure liquids in the polymer and the vapor‐liquid equilibrium data for the binary liquid mixture. The model was tested for two binary liquid mixture/polymer systems. The predicted values of solubilities are close to the experimental data. © 1993 John Wiley & Sons, Inc.
Determination of glass transition temperature from viscosity and conductivity measurements for an epoxy–amine system during curing
Authors: Koike Tsuneo
Published: April 2003

The melt viscosity and the direct current (dc) conductivity have been investigated for three bisphenol‐A novolac‐type epoxide oligomers (PGEBANs) that have some branching in each molecule in comparison with the diglycidyl either of bisphenol‐A (DGEBA) oligomer without branching. The novolac‐type PGEBAN oligomer has an experimental relationship between the melt viscosity (η) and the dc conductivity (σ), σ.ηk = const, which is the same form observed for the DGEBA oligomer. The exponent k has a linear relationship with the glass transition temperature (Tg) for the two types of oligomers with and without branching. The Tg dependence of k for the epoxide oligomers was used to analyze the Tg of a DGEBA—amine system that had some degree of branching in the molecule based on the bisphenol‐A structure. The Tg of the DGEBA—amine system, which was calculated from the k that had been nondestructively determined from the viscosity and the conductivity measurements, was consistent with the Tg experimentally measured by differential scanning calorimetry (DSC). © 1993 John Wiley & Sons, Inc.
Stress–optic relation and photo‐viscoplasticity for plastically deforming polymer solids
Authors: Nishitani Tadashi , Tsuji Masatoshi , Suetsugu Masahiro , Ogura Hiroyuki
Published: April 2003

Photo‐viscoplasticity for finding the stress distribution in a plastically deforming polymer solid is discussed by using the deduced stress‐optic relation. As an example, a practical application is shown for tension of the strip having semicircular notches in the plane stress state. © 1993 John Wiley & Sons, Inc.
Oxetane formation by addition of N‐substituted imidazoles to benzophenone and poly(4‐vinylbenzophenone)s
Authors: Ito Yoshikatsu , Kusunaga Yoshitaka , Tabata Kenichi , Arai Hitoshi , Meng Ji‐Ben , Matsuura Teruo
Published: April 2003

Photochemical oxetane formation by addition of 1‐methyl‐2,4,5‐triphenylimidazole (1a), 1,2‐dimethyl‐4,5‐diphenylimidazole (1b), and 1‐acetylimidazole (1c) to benzophenone (BP), poly(4‐vinylbenzophenone) (PVBP), and poly(styrene‐co‐4‐vinylbenzophenone) (PSVBP) was studied in the solution and solid phases. In solution, BP underwent the photoaddition smoothly to all three imidazoles 1a–1c. On the other hand, the photoaddition of PVBP and PSVBP depended on the imidazole employed, that is, 1b and 1c produced the corresponding oxetane, but 1a did not. The lack of oxetane formation from the polymeric BP and 1a is probably due to a rapid triplet‐sensitized decomposition of a once‐formed oxetane ring as a result of the intramolecular triplet energy transfer from a pendant benzophenone group. © 1993 John Wiley & Sons, Inc.
Model esterification of isophthalic and terphthalic acid with benzyl alcohol
Authors: Braam Ad W. M. , Scholtens Boudewijn J. R.
Published: April 2003

The esterification kinetics of isophthalic and terephthalic acid, with benzyl alcohol, were studied in the melt phase, which is a heterogeneous system because of the low solubilities of the phthalic acids. The relative concentrations of components and their conversions, α, were determined with HPLC. The effect of insolubility of the phthalic acids on the reaction kinetics can be described in two ways. For terephthalic acid, at 0 ≤ α ≤ 1, and for isophthalic acid, at α < 0.6, the esterification kinetics can be described with equations for a homogeneous system with only a substitution effect. An improved and more complete description for isophthalic acid is obtained with equations for a heterogeneous system, with a surface reaction rate constant and a ratio of reactive (at the surface) over nonreactive monomers (in the core, i.e., the surface to volume ratio). This model fits data for α < 0.7. The model parameters depend on the reaction temperature and the solubility of the phthalic acid. © 1993 John Wiley & Sons, Inc.
Carbon fiber heat treatment temperature and electrophysical properties of composite materials filled with these fibers
Authors: Letyagin S. V. , Shevchenko V. G. , Ponomarenko A. T. , Kestelman V. N.
Published: April 2003

Conductivities of composites filled with different carbon fibers having different heat treatment temperatures (HTT) have been studied. It is shown that conductivity realization coefficient decreases with the increase of HTT. © 1993 John Wiley & Sons, Inc.
An adhesion study of poly(phenylquinoxaline) on silicon wafers
Authors: Mcgarvey C. , Beccat P. , Zanier‐Szydlowski N.
Published: April 2003

This study is an investigation of the adhesion between poly(phenylquinoxaline) (PPQ) and γ‐aminopropyltriethoxysilane (γ‐APS)‐treated silicon wafers. In order to determine the locus of failure of the PPQ film‐coated wafers, when the coating was mechanically removed from the surface, the surface‐sensitive techniques of X‐ray photoelectron spectroscopy and contact angle measurements were employed. This permitted an analysis of the surface that was exposed when the film was removed from the substrate. In addition, FTIR spectroscopy was used to study the effect of the thermal treatment of the film‐coated wafers on the silane layer. Treatment of the coated wafers up to temperatures in excess of 250°C caused a deterioration of the γ‐APS layer, leading to a loss in adhesion of the coating, which was likely a result of the decrease in the density of the PPQ chains, which become anchored in the silane layer as the silanol groups condense during curing. When treatment temperatures are allowed to reach 400°C, the silane layer becomes severely degraded. It was found that the locus of failure remained the same, regardless of whether or not the coated wafer was subjected to aging in boiling water. © 1993 John Wiley & Sons, Inc.
Characterization of water‐soluble oligomer in acrylic acid‐styrene emulsion copolymerization
Authors: Wang Shou‐Ting , Poehlein Gary W.
Published: April 2003

Low molecular weight species, formed during the emulsion copolymerization of styrene and acrylic acid, were isolated and characterized. Samples of the reaction mixture were taken at different times during seeded and unseeded batch reactions. Reactions were stopped via injection of the samples into hydroquinone solutions and cooling with dry ice. Low molecular weight copolymers were separated and FTIR spectroscopy, mass spectroscopy, and 13C–NMR spectroscopy techniques were used to measure the oligomer composition, molecular weight, and copolymer sequence distribution, respectively.

The molecular size measurements should relate to the size of oligomeric radicals that grow in the water phase and enter polymer particles and the measurements should also relate to any water‐soluble polymer that is formed by termination in the aqueous phase. The molecules, found for copolymers formed from 90/10 weight ratios of styrene and acrylic acid, were comprised of 6–9 monomer units with 2–3 being styrene. Those formed from 60/40 styrene/AA ratios contained 13–16 monomer units with 1–2 styrene. Differences were observed between seeded and unseeded systems, especially in the amount and nature of the water‐soluble material formed early in the reaction. © 1993 John Wiley & Sons, Inc.
Benzophenone‐containing methylthiomethyl pendant polyimides as negative acting photoresists
Authors: Chiang Wen‐Yen , Mei Wang‐Ping
Published: April 2003

Four kinds of benzophenone‐containing polyimides, each of which carries different amount or distribution of methylthiomethyl (MTM) pendant groups, are applied as negative photoresists. Lithographic evaluation of these polyimides shows that PI‐42, the polyimide possessing the most, i.e., three MTM groups in a repeating unit on average, exhibits the highest sensitivity (D = 129 mJ/cm2), the highest contrast value (γ = 4.3), and the highest resolution capability (1.2‐μm lines and spaces can be resolved in a 1.0 μm thick film). In the air, the photopatterned lines obtained from all these polyimides are thermally stable up to 280°C. Upon treating at 400°C for 30 min, a 8% reduction in the linewidth is observed for the 3.8‐μm line of PI‐42. The optimum developing conditions of each of these title polymers are determined. Contrast curve analysis indicates that this resist system exhibits higher sensitivity at near UV region than at deep UV region. © 1993 John Wiley & Sons, Inc.
Polymeric photoinitiators bearing side‐chain benzoyldiphenylphosphinoxide moieties for UV curable coatings
Authors: Angiolini Luigi , Caretti Daniele , Carlini Carlo
Published: April 2003

Polymeric photoinitiators bearing side‐chain benzoyldiphenylphosphinoxide moieties have been prepared by reacting poly(4‐vinylbenzoic acid) or 4‐vinylbenzoic acid/methyl methacrylate copolymers with thionyl chloride followed by methoxydiphenylphosphine. The activity of the above polymeric systems has been checked in the UV curing of the acrylic clear‐coating formulation HDDA/BA and compared with that of the low molecular weight model 4‐isoprophylbenzoyldiphenylphosphinoxide. The stability to light and to hydrolytic conditions of the polymeric photoinitiators with respect ot the model has also been tested. The results obtained are discussed in terms of composition and structural features of these systems. © 1994 John Wiley & Sons, Inc.
Blend rules for homogenous and heterogenous systems
Authors: Furukawa Junji
Published: April 2003

Blend rules for (a) homogeneous and (b) heterogeneous systems are proposed in a form of P = (ϕm1P1 + ϕm2P2)/(ϕm1 + ϕm2), where P is the property, and ϕ, the volume fraction of component 1 or 2. For (a) m>1 and for P2>P1, an S‐shaped relation occurs between P or ϕ1. On the contrary, for (b) m<1, an anti‐S‐shaped relation occurs. When the hard component forms particles in continuous soft media, P is larger than the arithmetic mean P̄. When the interface slips, a mean of harmonic function holds so that 1/P = ϕ1/P1 + ϕ2/P2 and P < P̄. For special cases, i.e., the filler in the rubber and the rubber particles in the resin, the strength at break attains a maximum at 20 and 13% of particles, respectively. For rubber blended with a small amount of polypropylene by dynamic vulcanization, the latter forms a continuous phase, reinforcing rubber domains by the plastic force when the size of rubber particles becomes very small. © 1994 John Wiley & Sons, Inc.
Synthesis of zinc‐containing epoxy resin
Authors: Anand Manjit , Srivastava A. K.
Published: April 2003

Novel epoxy resins containing zinc acrylate have been synthesized by reacting zinc acrylate with bisphenol‐A and an excess of epichlorohydrin. Parameters such as epoxy equivalent weight, hydroxyl content, and hydrolyzable chlorine content have been estimated. These resins, characterized by IR, 1H‐NMR, and 13C‐NMR, have been evaluated by thermal analysis. Curing was carried out with polyamide at 130°C for 24 h. Cured resins have improved thermal and chemical resistance. The reaction follows first‐order kinetics with activation energy 86 and 34 kJ mol−1 in the presence and absence of zinc acrylate. The role of zinc, which increases epoxidation due to formation of complex with bisphenol‐A, has been discussed. © 1994 John Wiley & Sons, Inc.
A tensile rheometer for solid polymers containing volatile diluents
Authors: Monahan M. D. , Durning C. J.
Published: April 2003

A tensile rheometer capable of confining diluent is described. This rheometer makes it possible to characterize solid samples with imbibed diluent. Tensile stress‐relaxation data were obtained as a function of temperature for dry glassy semicrystalline poly(ethylene terephthalate) (PET) and as a function of composition for semicrystalline PET imbibed with dimethlformaide (DMF). Data on PET/DMF captures the glass‐rubber transition as DMF content is increased. © 1994 John Wiley & Sons, Inc.
Poly(ethylene terephthalate)/polyarylate blends: Mixing and interchange reactions in injection molding
Authors: Martínez J. M. , Nazábal J. , Eguiazábal J. I.
Published: April 2003

Blends composed of poly(ethylene terephthalate) and a polyarylate have been melt‐mixed and molded in a reciprocating screw injection‐molding machine for different plasticization times. Interchange reactions between the blend components occur during processing and at a greater level as the plasticization time increases. These reactions led to a progressive homogenization of the blends as well as to a hindered crystallization of PET. The effect of the plasticization time on the mechanical properties of the blends seems to be a consequence of interchange reactions as well as of the degradation of the blends at the highest plasticization times. © 1994 John Wiley & Sons, Inc.
Importance of solubility phenomena during the separation of the ethylene–polyethylene mixture in the industrial low density polyethylene process
Authors: Bogdanović Vojislav Ž. , Tasić Aleksander Ž. , Djordjević Bojan D.
Published: April 2003

The solubility values of ethylene in polyethylene and vice versa have been evaluated for the process conditions. These results could be used in solving real problems of PE‐LD process. © 1994 John Wiley & Sons, Inc.
A rheological and morphological explanation of the inherent blocking force in LLDPE blown films
Authors: Hazlitt Lonnie G. , Karande Seema V. , Castille Merrick J.
Published: April 2003

The inherent film blocking force in linear low‐density polyethylene (LLDPE) blown films was studied using several LLDPEs with varying density, molecular weight, and molecular weight distribution (MWD). Melt elasticity, fabrication conditions, and film surface morphology were found to have a significant effect on the inherent film‐blocking force in LLDPE blown films. A comprehensive mechanism for the film‐blocking force based on molecular weight, rheology, and morphology studies is proposed. LLDPEs with higher density exhibited a lower blocking force. At a constant density, the LLDPEs with higher melt elasticities (slower relaxation rates) exhibited rougher film‐surface morphology and produced blown films with lower blocking force. These LLDPEs with an inherent low blocking force are used in grocery sacks, trash bags, and merchandise bag markets where bag openability is a critical performance property. © 1994 John Wiley & Sons, Inc.
XPS study of dimethylolurea polymers and hollow fibers modified by these polymers. I. XPS study of dimethylolurea polymers
Authors: Rouzies P. , Lebugle A.
Published: April 2003

Polycondensation of dimethylolurea leads to the formation of a gel or a film according to the experimental conditions. Both forms of the polymer would be characterized by a specific chemical structure, i.e., dimethylene ether or diaminomethylene, respectively. We studied both forms of dimethylolurea polymer by XPS and have shown that it is possible to distinguish them using this technique. The study of the carbon peak shape attributed mainly a dimethylene ether structure to the gel and a diaminomethylene structure to the film. © 1994 John Wiley & Sons, Inc.
Physical characteristics of silk fibers modified with dibasic acid anhydrides
Authors: Tsukada Masuhiro , Gotoh Yoko , Shiozaki Hideki , Freddi Giuliano , Crighton John S.
Published: April 2003

The objective of this study was to investigate the physical properties of silk fibers modified with dibasic acid anhydrides. These are potentially attractive modifying agents to reduce the rate of photoyellowing of silk during and following UV irradiation. Several analytical techniques were employed, which included the measurement of the basic mechanical properties (tensile strength and elongation at break), equilibrium regain, amino acid analysis, dynamic viscoelastic measurements, X‐ray diffractometry, and scanning electron microscopy (SEM). The succinylated silk fibers, which have been conditioned under different relative humidity atmospheres, always exhibited slightly higher equilibrium regain values than those of equivalently conditioned glutarylated silks. The amount of the basic amino acid residues slightly decreased following modification with both succinic and glutaric anhydrides. The birefringence values and the isotropic refractive indices decreased only slightly, which suggests that the fine structure of the treated silk fibers was not significantly altered. The X‐ray diffraction curves demonstrated that no changes in the crystalline structure were induced by reaction with dibasic acid anhydrides. The tensile properties of the modified silks remained more or less unchanged. Only the initial tensile resistance of glutarylated silks in the dry state significantly decreased. The dynamic viscoelastic behavior of modified silk fibers was characterized by a reduced thermal stability. In fact, the onset temperature of the prominent E peak corresponding to the molecular movement shifted to lower values. The surfaces of modified silk fibers were as smooth as that of the untreated control sample. © 1994 John Wiley & Sons, Inc.
Electric‐field‐sensitive polymers: Reversible bending of rod‐shaped polymer gels in salt solutions
Authors: Choi Oe Soon , Yuk Soon Hong , Lee Hai Bang , Jhon Mu Shik
Published: April 2003

Neutral gel (acrylamide [AAm] gel) and anionic gel (copolymer gel of 2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid [AMPSA] and butyl methacrylate [BMA]) were prepared to observe the bending phenomena in various salt solutions. The bending pattern of AAm gel was closely related to salts used in the aqueous media. The competition NMR technique was used to understand the interaction of salts with the polymer matrix. In the case of copolymer gel, the bending pattern did not show the salt dependence and the bending angle decreased after reaching a maximum. © 1994 John Wiley & Sons, Inc.
Photo‐ and thermal‐oxidation of the nonwoven polypropylene fabric studied by FT‐IR photoacoustic spectroscopy
Authors: Yang Charles Q. , Martin Linette K.
Published: April 2003

The photo‐ and thermal‐oxidation of a nonwoven polypropylene fabric was investigated using Fourier transform infrared photoacoustic spectroscopy (FT‐IR/PAS). The infrared spectroscopic data indicate that alcohol, peroxide, aldehyde, ketone, carboxylic acid, and anhydride were formed as the products of the thermal oxidation and photooxidation of the polypropylene fabric. Ester was also formed during the thermal oxidation process. The thermal oxidation was accelerated after an initiation period. It was found that thermal oxidation occurred homogeneously between the surfaces of the fabric and its bulk. For the polypropylene fabric irradiated by ultraviolet (UV) radiation, however, the highest degree of oxidation occurred in the surface of the fabric facing the UV radiation source. It was also found that the UV radiation at 254 nm caused photooxidation of polyropylene. No photooxidation was observed in the fabric exposed to the UV radiation at 350 nm under the same conditions. © 1994 John Wiley & Sons, Inc.
Studies on PI/PI adhesion strength
Authors: Wang Tsung‐Hsiung , Ho Syh‐Ming , Chen Han‐Lung , Chen Ker‐Ming , Liang Syh‐Ming , Hung Aina
Published: April 2003

The adhesion of polyimide to polyimide was studied by measuring the peel strength of various polyimide–polyimide composites. Different factors such as diffusion of polyamic acid to polyimide substrate, contact angle, wettability, and the thermal expansion coefficient of polyimide films and the presence of siloxane can affect this adhesion and are discussed in this article. © 1994 John Wiley & Sons, Inc.
Structure–property relationship of HTPB‐based propellants. III. Optimization trials with varying levels of diol–triol contents
Authors: Manjari R. , Pandureng L. P. , Somasundaran U. I. , Sriram T.
Published: April 2003

A systematic study has been conducted on a composite solid propellant formulation using hydroxyl‐terminated polybutadiene (HTPB) prepolymer with varying molecular weights and hydroxyl values. Fairly extensive regions of resin parameters have been studied. Contours of important propellant properties have been laid down. In this set of experiments, varying levels of diol and triol contents were used at two different NCO/OH ratios to arrive at the optimum level needed for different grades of HTPB resin. It is seen that different grades of HTPB resin require varying levels of diol–triol contents to give similar properties for the end product. Also, for the best performance, varying the diol–triol ratio at the optimum level of the diol–triol content is necessary. © 1994 John Wiley & Sons, Inc.
Porous polydimethylsiloxane membranes treated with aminopropyltrimethoxysilane
Authors: Kobayashi Takaomi , Saitoh Hitoshi , Fujii Nobuyuki
Published: April 2003

Polydimethylsiloxane (PDMS) membranes were made by catalytic hydrosilylation of a siloxane compound having a vinyl group and an SiH group in the presence of 1,4‐dioxane. By washing it with water many pores were formed in the membrane. Then, the pore size of the membrane was controlled by treatment of aminopropyltrimethoxysilane (APTMS) solution. When increasing the APTMS concentration, the pore size of the membrane was reduced by the formation of APTMS oligomer on the surface of the membrane. The characteristics of the membrane was examined by IR, ATR‐IR, and SEM techniques. Also, the permeation properties of dextrans and polystyrene latexes through the treated membrane were examined by the ultrafiltration method. © 1994 John Wiley & Sons, Inc.
Emulsion polymerization of vinyl acetate in a tubular loop reactor
Authors: Iabbadène Akli , Bataille Pierre
Published: April 2003

A study was conducted on the emulsion polymerization of vinyl acetate using a loop reactor. Among the variables studied were the agitation, that is, the Reynold's number, and the effect of the presence of silver ions on the reaction rate. The molecular weight and molecular weight distribution of the polymer were determined as well as its particle size. The results are compared with earlier work done in a batch, a continuous tubular, and in a tubular loop reactor. © 1994 John Wiley & Sons, Inc.
Allylamine‐adducted bismaleimide resins. II. Their physical/mechanical properties and morphology
Authors: Lin King‐Fu , Lin Jin‐Sing
Published: April 2003

Physical/mechanical properties of various cured allylamine‐adducted bismaleimides (A‐BMI), such as allylamine‐adducted 4,4′‐bismaleimidodiphenylmethane (A‐BDM), and allylamine‐adducted 4,4′‐bismaleimidodiphenylether (A‐BDE) were investigated and correlated to their morphology. In the previous study, two types of the curing reactions were found one is the homopolymerization through the opening of double bonds in the maleimide groups and the other is the reactions between allyl groups and benzene rings. Dynamic mechanical analysis and scanning electron microscopy of cured A‐BMI indicate that the network produced by homopolymerization is immiscible with that produced by the other reactions. The glass‐transition temperature (Tg) of the former network is lower than that of the latter. In addition, the 50% A‐BDM prepared by reacting BDM with 50 mol % allylamine has the optimal physical/mechanical properties after cure, such as the highest Tg and the highest flexural strength and modulus among the A‐BDM. Moreover, the decomposition temperature of 50% A‐BDM is 450°C, only about 40°C lower than that of the pure BDM. © 1994 John Wiley & Sons, Inc.
IGC study of surface properties of adsorbed styrene/methacrylic acid diblock polymers
Authors: Bosse F. , Eisenberg Adi , Xu Ruijian , Schreiber H. P.
Published: April 2003

An inverse gas chromatographic study has been carried out on a styrene/methacrylic acid diblock polymer adsorbed on particulates of varying acid/base interaction potential. Acid/base interactions between polymer and substrate were shown to result in the selective adsorption of copolymer moieties, leading to interphase surface compositions that varied with thickness. At higher interphase thicknesses, bulk and surface compositions became similar; however, depending on the interaction potential of the adsorbent, the interphase thicknesses at this point varied from 100 to 1000 Å. Adsorbed diblock interphases are to be considered nonisotropic in local composition and molecular conformation. These properties may make possible designing diblock interphases to meet specific compatibilization requirements in polymer composites. © 1994 John Wiley & Sons, Inc.
Cross‐linking of bisepoxide with divalent metal salts of p‐aminobenzoic acid and anhydride
Authors: Takechi Shigetoshi , Matsuda Hideaki
Published: April 2003

Cross‐linking of bisepoxide with divalent metal salts of p‐aminobenzoic acid and dicarboxylic acid anhydride was investigated. As the bisepoxide, bisphenol A diglycidyl ether was used and hexahydrophthalic anhydride was the anhydride used. As the divalent metal, Mg and Ca were selected. In the cross‐linking reactions, the metal salts showed catalytic activities. In this case, the salt containing Mg exhibited higher catalytic activities than that containing Ca. The cross‐linking reaction was supposed to proceed via a complex mechanism. The cured resins obtained contained amide and ester groups and ionic linkages. As for the physical properties of the novel metal‐containing cured resins, tensile and flexural strengths decreased with an increase in the metal content. However, Rockwell hardness was not affected by the metal content. There was a good correlation between heat distortion temperature and Tg determined by dynamic mechanical properties. Against boiling water, the resins exhibited low weight gain, low change in dimension, and no change in external appearance. In addition, thermal decomposition was accelerated by the incorporated metal. © 1994 John Wiley & Sons, Inc.
Multiphase materials with lignin. XII. Blends of poly(vinyl chloride) with lignin–caprolactone copolymers
Authors: De Oliveira Willer , Glasser Wolfgang G.
Published: April 2003

A previously described starlike copolymer consisting of a lignin derivative (hydroxypropyl lignin) and caprolactone has been blended with poly(vinyl chloride) (PVC) over a composition range of 0–100%. Solvent‐cast films of the blends were examined with regard to thermal, mechanical, crystallinity, and morphological characteristics. In addition, the blends were examined with regard to aging effects. The results suggest that the lignin/caprolactone copolymer forms either a miscible (by thermal analysis) or a nearly miscible (with phase dimensions in the order of 10–30 nm) system in which physical properties are modified over a wide range of modulus and elongation. Blends with copolymer content exceeding 50% reveal partial caprolactone crystallinity that increases with age. Lignin derivative not copolymerized with caprolactone, by contrast, produces macrophase‐separated structures with exceedingly poor properties. Lignin caprolactone starlike copolymers are materials ideally suited as plasticizers for PVC. © 1994 John Wiley & Sons, Inc.
Kinetics of poly(acrylic acid) adsorption at the liquid–glass interface
Authors: Bajpai A. K.
Published: April 2003

The kinetic behavior of the adsorption of weak polyacid, namely, poly(acrylic acid) on a smooth glass surface has been studied at 30°C. For the evaluation of various adsorption parameters—the adsorption coefficient, surface coverage (θ), and thickness of the adsorbed layer—a new simple kinetic model has been proposed. The effect of the factors such as pH, electrolyte concentration, and molecular weight on adsorption behavior has been studied. © 1994 John Wiley & Sons, Inc.
Self‐ and mutual‐diffusion coefficients in the dodecane/polystyrene system
Authors: Kim Dukjoon , Caruthers James M. , Peppas Nikolaos A. , von Meerwall Ernst
Published: April 2003

The self‐diffusion coefficient of dodecane in cross‐linked polystyrene was measured using pulsed gradient spin echo nuclear magnetic resonance (PGSE–NMR) spectroscopy. The concentration and temperature dependence of the diffusion coefficient was analyzed by the Fujita and Vrentas–Duda models. Parameters describing the Fujita model were determined from fitting of diffusion data to the PVT behavior of the system. Parameters describing the Vrentas–Duda model were determined from the analysis of the viscosity of dodecane, the viscoelastic relaxation properties, and the glass transition temperature of polystyrene as well as from the diffusion coefficient of the system, measured from independent experiments. Both the Fujita and Vrentas–Duda models described well the concentration and temperature dependence of the diffusion coefficient. Mutual diffusion coefficients were determined from these results. © 1994 John Wiley & Sons, Inc.
Effect of siloxane chain lengths of monomers on characteristics of pervaporation membranes prepared by plasma polymerization
Authors: Matsuyama Hideto , Kariya Ayao , Teramoto Masaaki
Published: April 2003

Plasma‐polymerized membranes were prepared from a series of monomers with the different siloxane chain lenghts, i. e., hexamethyldisiloxane, octamethyltrisiloxane, and decamethyltetrasiloxane, and effects of the starting monomers on both the structures of the plasma polymers and the pervaporation characteristics of ethanol/water mixture were investigated. By IR and XPS measurements, it was found that with increase of the siloxane chain lenghts of the monomer the siloxane chains in the plasma polymers were linked more continuously and smaller amounts of additional oxygen were newly incorporated into the polymers. All membranes obtained from the three monomers were found to be ethanol‐permselective. From the standpoint of obtaining both high selectivity and high permeation rate, the monomer with the longer siloxane chain was profitable. The relations between the results of the analysis of the plasma polymers by IR and XPS measurements and the pervaporation characteristics obtained are discussed. © 1994 John Wiley & Sons, Inc.
The role of steric effects in the adsorption of chemically similar probes to a poly(methyl methacrylate) surface
Authors: Jacob Pauline , Arola Darren , Berg John
Published: April 2003

The role of steric effects in the adsorption of chemically similar acidic probes to the model basic surface of poly(methyl methacrylate) (PMMA) was examined using the technique of inverse gas chromatography (IGC). The results were expressed in terms of the acid‐base contribution to the Gibbs free‐energy change upon adsorption. The acid‐base component of the adsorption free energy, computed on the basis of theoretical modes of adduct formation, was found to depend strongly on the molecular structure of the adsorbate, suggesting the importance of steric effects. © 1994 John Wiley & Sons, Inc.
Cationic graft copolymerization of tetrahydrofuran onto bromodeoxycellulose
Authors: Aoki Nobuyoshi , Furuhata Ken‐Ichi , Sakamoto Munenori
Published: April 2003

Cationic graft copolymerization of tetrahydrofuran onto halodeoxycelluloses, which were prepared under homogeneous conditions, was studied with silver tetrafluoroborate as an initiator. 6‐Bromo‐6‐deoxycelluloses gave graft copolymers, insoluble but swollen in tetrahydrofuran, whereas chlorodeoxycelluloses gave no graft copolymer. The graft copolymers were hydrolyzed in 2N HCl to give hydrolyzate solutions and insoluble solids. The hydrolyzate was found to be composed of 6‐O‐(4‐hydroxybutyl) glucose and 6‐O‐(9‐hydroxy‐5‐oxanonyl) glucose as well as oligomers of tetrahydrofuran by gas chromatography and gas chromatography–mass spectrometry after trifluoroacetylation. The insoluble solid was cross‐linked polyoxytetramethylene, which could be hydrolyzed only very slowly in 2N HCl to yield oligomers of tetrahydrofuran. Thermal behavior of the graft copolymer was compared with that of cellulose and of homopolymer of tetrahydrofuran. © 1994 John Wiley & Sons, Inc.
Thermal characteristics of unsaturated dicarboxylic acid durable press finishing systems
Authors: Trask‐Morrell Brenda J. , Choi Hyung‐Min
Published: April 2003

Thermoanalytical (TA) studies including differential scanning calorimetric (DSC) and thermogravimetric (TG) analyses were carried out to measure characteristics of dried mixtures based on two unsaturated polycarboxylic acids. Model 9% treatment (pad) solutions of maleic (M) and/or itaconic (I) acid, with and without potassium peroxydisulfate (K) as the free‐radical initiator, were prepared with sodium hypophosphite (H) as the catalyst and vacuum oven‐dried. DSC thermograms varied with each component; even the presence of a small amount of component K was evident. TG residue production and maximum rates of weight loss were the most useful thermal parameters. Residue/rate factors, used previously as predictors, were calculated. Previous studies indicated that high residues and low rates were indicators of combinations of reactants that resulted in good durable press treatments for fabrics. Residue/rate factors were used to rank the six mixtures that reflect actual fabric treatment combinations: MH, IH, MIH, and those same three with the initiator present. Rankings indicated that the presence of the initiator significantly increased the residue/rate factor for IHK and for MIHK. The presence of the initiator appears more beneficial to itaconic acid than to maleic acid. The rankings by the TA predictor agreed with textile properties measuring appearance and strength. © 1994 John Wiley & Sons, Inc.
Shear degradation of vinylidene chloride copolymers
Authors: Betso S. R. , Berdasco J. A. , Debney M. F. , Murphy G. L. , Rome N. P. , Richards S. G. , Howell B. A.
Published: April 2003

Thermally induced dehydrochlorination is a well‐established and prominent degradation mode for vinylidene chloride copolymers. During extrusion, other processes may represent significant degradation pathways. Under shear in air, both oxidative chain‐scission and cross‐linking are prominent processes for both vinylidene chloride/vinyl chloride and vinylidene chloride/methyl acrylate copolymers. Both processes are dependent upon shear rate and temperature. The shear‐stress dependency can be modeled by a kinetic expression that incorporates shear stress into the Arrhenius preexponential factor. Vinylidene chloride/methyl acrylate copolymers appear to be somewhat more susceptible to oxidative chain‐scission than are comparable vinylidene chloride/vinyl chloride copolymers, presumably because of a rapid oxidative attack at exposed methyl acrylate units. Shear‐induced degradation of these materials in air is characterized by early predominant chain‐scission with cross‐linking assuming a greater importance as a function of time. Degradation under shear in a nonoxidative environment is a much simpler process—oxidative chain‐scission is suppressed and cross‐linking is very similar to that observed in air. © 1994 John Wiley & Sons, Inc.
New routes to phenylsilicones
Authors: Stein Judith , Lettko Kevin X. , King Joseph A. , Colborn Robert E.
Published: April 2003

Two alternative nonhalogen routes for the synthesis of phenylsilanes have been explored. In the first method, 2,3‐dimethylbutadiene is reacted with divinyltetramethyldisiloxane via a Diels–Alder reaction. The product can then be aromatized. In the second method, cyclohexadiene undergoes hydrosilylation and the resultant product can be aromatized using palladium on carbon with nitrobenzene as an electron accepter. Phenylsilicones can be prepared in a single step in which a silicone hydride fluid and cyclohexadiene are refluxed in the presence of Pt/C (platinum on carbon) and nitrobenzene. © 1994 John Wiley & Sons, Inc.