bluuebunny/crossref_metadata_2025_split huggingface dataset:
Physical properties of silk fibers treated with ethylene glycol diglycidyl ether by the pad/batch method
Authors: Tsukada Masuhiro , Shiozaki Hideki , Goto Yoko , Freddi Giuliano 
Published: April 2003

AbstractThis paper deals with the epoxide treatment of silk fabrics by the pad/batch method. The optimum reaction conditions, i.e., NaOH concentration, and reaction temperature were 2.5 g/L and 30°C, respectively. A weight gain of 8.5% was attained at a reaction time of 6 h. This value slightly increased to 10% after 24 h. The reactivity of tyrosine and basic amino acid residues was dependent on the reaction time and did not significantly differ from the results of epoxide‐treated silk fiber by the conventional method in tetrachloroethylene. The moisture regain slightly decreased at 4% weight gain and then increased with the epoxide content, exceeding the value of the untreated control. The crease recovery of the epoxide‐treated silk fabrics measured in the wet state was significantly improved, whereas that in the dry state was almost unchanged. The rate of photoyellowing of the epoxide‐treated silk fabrics by the pad/batch method was reduced significantly compared with that of the untreated control. Among the mechanical properties, elongation at break and tensile modulus remained unchanged, whereas the tensile strength slightly increased following the epoxide reaction. The thermal properties were evaluated by DSC and TGA and on the basis of the dynamic viscoelastic measurements. The DSC curve of the epoxide‐treated sample showed a slight increase of the decomposition temperature of silk fibroin. The rate of weight loss determined by TGA remained unchanged regardless of the chemical modification, whereas the peak of loss modulus became broader and shifted to lower temperature. The X‐ray diffractograms showed that the crystalline structure of silk fibers was not affected by the reaction with epoxides. © 1993 John Wiley & Sons, Inc.
Photoinitiated oxidation of heterophasic ethylene–propylene copolymers. I. Comparison of oxidation products
Authors: Singh R. P. , Mani R. , Sivaram S. , Lacoste J. , Vaillant D. 
Published: April 2003

AbstractDetailed photoproducts from photoirradiation of heterophasic ethylene‐propylene copolymers and their fractions have been compared by infrared spectroscopy combined with chemical derivatization. The oxidized films were treated with gaseous NH3, SF4, and NO for the rapid identification and resolution of the various carbonyl species, alcohols, and hydroperoxides. The photoproduct formation depends upon the composition of the sample. The heterogeneities in thin films were also determined by micro FTIR spectroscopy. © 1993 John Wiley & Sons, Inc.
Prediction of gas permeability of nylon from glass‐transition temperature
Authors: Eichler Sigal , Miltz Joseph 
Published: April 2003

AbstractA method to predict the permeability coefficients of gases in nylons at different relative humidities was proposed. The model was tested for Nylon 6 and 6,6 with oxygen as a permeant. Very good agreement between the predicted and experimentally determined values was found. © 1993 John Wiley & Sons, Inc.
Isolation and identity verification of polyalkylene glycols in fire resistant hydraulic fluids type C and D U
Authors: Van Dam J. , Daenens P. , Busson R. 
Published: April 2003

AbstractA procedure to verify the identity of hydraulic fluids (HF) type C and D U is described. Different gel filtration systems were tested to separate the constitutive components. After fractionation of the mixture, IR and NMR spectroscopy were tried for their suitability in verifying the identity of the different constituents. The combination of aqueous gel filtration chromatography and IR spectroscopy was found suitable to separate and identify the different components of HFC fluids. For HFD U fluids, a modified gel filtration system was used and NMR spectroscopy was necessary to give a decisive answer about their identity. © 1993 John Wiley & Sons, Inc.
Influence of chain microstructure on thermodegradative behavior of furfuryl methacrylate‐N‐vinylpyrrolidone random copolymers by thermogravimetry
Authors: Peniche Carlos , Zaldívar Dionisio , Bulay Anna , Román Julio San 
Published: April 2003

AbstractThe thermal behaviour of random copolymers of furfuryl methacrylate (F) and N‐vinylpyrrolidone (P) was studied by means of dynamic thermogravimetric analysis (TGA) in the range 100–600°C. The dynamic experiments show that these copolymers exhibit two degradation steps in the intervals 260–320°C and 350–520°C, respectively. The normalized weight loss in the low temperature interval increases as the mole fraction of F in the copolymer mF increases, whereas an inverted trend in the high temperature interval is observed. The apparent activation energy Ea of the first degradation step for copolymers prepared with different composition, was obtained according to the treatment suggested by Broido. A plot of the values of Ea versus the F diad molar fraction in the copolymer chains mFF gave a straight line that indicates that there is a direct relationship between the thermogravimetric behaviour of these systems and their corresponding microstructure, that is, the distribution of comonomeric units along the copolymers chains. The first decomposition step was also studied by isothermal TGA and a good linearity for the variation of the weight loss percentage ΔW versus mF at least during the first 30 min of treatment was obtained. These results also indicate that from a kinetic point of view the isothermal degradation in these conditions follows a first order behaviour and the corresponding reaction rate constants increase linearly with mFF. © 1993 John Wiley & Sons, Inc.
Sequential‐interpenetrating polymer networks from castor oil‐based polyesters. XXVI.
Authors: Suthar Bhikhu , Dave Mayank , Jadav Kanak 
Published: April 2003

AbstractPolyesters were obtained from castor oil and dibasic acids for example, malonic, succinic, glutaric, adipic, suberic, and sebacic acids. These prepolyesters were characterized by infrared spectrometry, viscosimetric measurements, and molecular weight determinations (GPC). These prepolyesters were mixed with methyl methacrylate and were subsequently polymerized by free radical polymerization by benzoyl peroxide in the presence of the crosslinker ethylene glycol dimethacrylate. Polyester/poly(methyl methacrylate)‐interpenetrating polymer networks, PPE/PMMA IPNs, were obtained as soft and opaque elastomers by the transfer molding technique. These IPNs were characterized by static mechanical properties, differential scanning calorimetry (DSC), and thermogravimetry. © 1993 John Wiley & Sons, Inc.
Stress relaxation behavior of polyacetal–thermoplastic polyurethane elastomer blends
Authors: Kumar G. , Arindam Mr. , Neelakantan N. R. , Subramanian N. 
Published: April 2003

AbstractThe yield stress of polyacetal (POM) decreases monotonically with the incorporation of thermoplastic polyurethane (TPU) elastomer in POM/TPU blends as would be anticipated. However, the impact strength of the resultant POM/TPU blends increases initially up to 30% TPU and thereafter decreases with the addition of TPU. Stress relaxation measurements in simple extension were carried out for POM and its blends with 10, 20, and 30% TPU at a constant temperature (30°C). Rate of loss of the relaxation modulus was found to be a nonlinear function of time. It has been demonstrated that the stress relaxation modulus values measured at different strains can be superimposed by a shift along the logarithmic time axis to yield master curves of modulus over an extended time period. It has also been found that while it is possible to determine, at any strain, relaxation curves covering an appreciable time range, the demarcation of linear and nonlinear behavior ranges of stress could not be done for these materials as all the strain values chosen in our experiments were in the region of linear behavior. © 1993 John Wiley & Sons, Inc.
Mechanical properties of thermoplastic elastomers of poly(butylene terephthalate) and poly(ethylene glycol) in a bending deformation
Authors: Wang Shuhong , Mark J. E. , Erman B. , Fakirov S. 
Published: April 2003

AbstractThermoplastic elastomers based on poly(butylene terephthalate) (PBT) and poly(ethylene glycol) (PEG) were studied by bending‐creep measurements. The dependence of the creep compliance on the composition of the block copolymer was determined, and the experimental results were compared with calculated results to obtain a better understanding of structure‐property relationships for this class of materials. The hard PBT domains in the rubbery PEG matrix make a large contribution to the mechanical strength and hardness, presumably serving as reinforcing fillers as well as cross‐links. Relaxation effects were found to decrease significantly with increase in hard‐segment content. © 1994 John Wiley & Sons, Inc.
The thermal decomposition of sulfenamide accelerators
Authors: Gradwell M. H. S. , Mcgill W. J. 
Published: April 2003

AbstractThe thermal decomposition of three sulfenamide accelerators N‐cyclohexylbenzothiazole sulfenamide (CBS), 2‐(4‐morpholinothio) benzothiazole (MOR) and 2‐t‐butylaminobenzothiazole sulfenamide (TBBS) were investigated by differential scanning calorimetry. The sulfenamides decompose rapidly at 210–220°C, yielding a number of products, including reactive polysulfidic complexes. Thus, CBS gives N‐cyclohexylamino‐2‐benzothiazole polysulfides (CBP), 2‐bisbenzothiazole‐2,2′‐disulfide (MBTS), 2‐bisbenzothiazole‐2,2′‐polysulfides (MBTP), 2‐bisbenzothiazole‐2,2′‐monosulfide (MBTM), 2‐mercaptobenzothiazole (MBT), and 2‐N‐cyclohexylaminobenzothiazole (CB). The polysulfides are unstable, and on prolonged heating, only MBT and CB remain. The amine fragment of the accelerator is present as the amine salt of MBT. At lower temperatures, the sulfenamides are relatively stable. MOR forms an analogous product spectrum. The decomposition of TBBS is endothermic, in contrast to the exothermic reaction observed with CBS and MOR, and the concentrations of the various polysulfides do not decrease on prolonged heating. Reaction mechanisms are proposed to account for the formation of the products. © 1994 John Wiley & Sons, Inc.
Gamma‐sterilization effects and influence of the molecular weight distribution on the postirradiation resistance of polypropylene for medical devices
Authors: Martakis Nick , Niaounakis Michael , Pissimissis Dimitris 
Published: April 2003

AbstractIn the present study, the dose‐rate effects of γ‐irradiation in air on two isotactic polypropylene grades of different molecular weight distribution, used for medical devices, were investigated. The thermal, mechanical, rheological, and photometric properties of these materials were examined using DSC, stress–strain measurements, MFI, and a yellow index. At low dose rates (0.12 Mrad/h), the oxygen diffusion parameter prevailed. At high dose rates (2.84 Mrad/h), the thermal degradation became dominant. However, at high dose rates, an increase in sample temperature was monitored. This temperature rise is thought to increase the oxygen diffusion rate, peroxide decomposition, and radical migration. As a result, intermediate dose rates (in the region of 0.72 Mrad/h) gave the lowest changes in physical properties in both samples. Furthermore, it was found that the polypropylene grade of broader molecular weight distribution and lower Mn had a higher γ‐irradiation and postirradiation resistance. © 1994 John Wiley & Sons, Inc.
Cure behavior of paper–phenolic composite systems: Kinetic modeling
Authors: Kiran Erdogan , Iyer Rajan 
Published: April 2003

AbstractCure reactions in paper–phenolic composite systems were studied by differential scanning calorimetry. A phenomenological approach was used to characterize the cure kinetics. Various kinetic models including homogeneous reaction, diffusion‐controlled reactions, surface reaction and phase boundary movement, and nucleation and growth‐type kinetic models have been tested. Kinetic analyses using integral and derivative procedures on dynamic and isothermal data indicate that the cure reaction data can be described well with the homogeneous first‐order reaction model or the Jander three‐dimensional diffusion model. The activation energies are found to be in the range 20–40 kj/mol. © 1994 John Wiley & Sons, Inc.
Reactivity ratios and microstructure of vinyl acetate–butyl methacrylate copolymers: NMR study
Authors: Brar A. S. , Charan Shiv 
Published: April 2003

AbstractVinyl acetate/butyl methacrylate (V/B) copolymers were prepared by free‐radical solution polymerization in benzene. Compositions of the copolymers have been obtained from 1H‐NMR spectroscopy. Kelen–Tüdös (KT), the nonlinear error in variables method (EVM), and 13C{1H}‐NMR spectra of the copolymers were utilized to calculate the comonomer reactivity ratios. The reactivity from different methods are rV = 0.06 ± 0.02, rB = 26.34 ± 8.49 (KT); rV = 0.06 ± 0.01, rB = 26.88 ± 3.59 (EVM); and rV = 0.06, rB = 18.20 (13C‐NMR spectroscopy). The microstructure in terms of V‐ and B‐centered triad fractions was obtained using 13C{1H}‐NMR spectra of copolymers. The copolymerization behavior of V/B copolymers as a function of conversion was also studied. © 1994 John Wiley & Sons, Inc.
Decomposition of polyurethane foams by alkanolamines
Authors: Kanaya Kouji , Takahashi Shizuo 
Published: April 2003

AbstractMethylene diphenyl isocyanate (MDI)‐based polyurethane flexible foams were decomposed by alkanolamines without a catalyst at 150°C. The decomposition products were completely separated into two layers. The upper liquid layer was a polyether polyol, and the lower liquid layer was methylene diphenyl amine (MDA) and alkanolamine derivatives. These layers were analyzed using gel permeation chromatography (GPC) and 13C‐NMR. The upper layer was obtained as a relatively pure polyether. The lower layer was observed to be MDA and 2‐hydroxyethyl carbamic acid ester prepared from alcoholysis products during the decomposition reaction. It was thought that the decomposition process of polyurethane foam by alkanolamines was not aminolysis but alcoholysis. © 1994 John Wiley & Sons, Inc.
Polymer–filler interaction in polyurethane kraft lignin polyblends
Authors: Feldman D. , Lacasse M. A. 
Published: April 2003

AbstractKraft lignin fillers have been shown to enhance the mechanical characteristics of different types of polymeric‐based sealants; however, the mechanism for reinforcement and the degree of interaction was not well understood. In this study, interactions between a polyurethane‐based elastomer and various Kraft lignin fillers as well as kaolin and titanium dioxide filler combinations were investigated in an effort to determine the most useful elastomer–filler combination for use as a construction joint sealant. A relationship that describes and relates the characteristics of polymer–filler interaction requires that the surface‐energy properties of both the polymer matrix and the filler be determined. Measurements using the sessile drop method are used to evaluate the critical surface energy of the polymer matrix, whereas the rate of rise of a liquid through a bed of filler provides the means to evaluate the surface energetics of the various fillers. Results obtained from this study show that the tensile modulus of the different elastomer formulations are proportional to the equilibrium work of adhesion, as described by the relationship derived by Lee that relates the degree of interaction of the formulation components and the mechanical properties of the blends. © 1994 John Wiley & Sons, Inc.
A phenomenology based equation of state for polymer melts
Authors: Arends C. B. 
Published: April 2003

AbstractAn equation of state for polymer melts has been devised from observation on pressure–volume–temperature data for several thermoplastics. The final equation has the form (P + Π − mT ln (cV*)) ln (cV*) = gT, where P is pressure; T, absolute temperature, V*, the volume normalized by van der Waal's volume, and Π, m, g, and c, parameters. Pertinent ancillary relationships include a “universal” bulk modulus vs. a normalized volume function and an observation that the thermal expansion coefficient is solely dependent on pressure. We find that the parameter “Π” is precisely the first derivative of internal energy with respect to volume and is evaluated from the thermal expansion coefficient and bulk modulus. It appears that “Π” is constant over a wide range of conditions. The parameters “m” and “g” are related through the bulk modulus relation. Finally, “c” has been found to be nearly a constant whose action is to change the volume reference state to the melt volume when extrapolated to absolute zero. The “universal” nature of the temperature‐reduced bulk modulus and the constancy of Π suggest that the melt state is controlled by entropy rather than by potential energy. © 1994 John Wiley & Sons, Inc.
Lower critical solution temperature (LCST) polymer solution for clear/cloud glazing applications
Authors: Gundlach D. P. , Burdett K. A. 
Published: April 2003

AbstractAn aqueous‐based clear/cloud solution was developed using poly(vinyl methyl ether) and an antifreeze mixture of ethylene and propylene glycols. The solution has a controllable cloud point from 15 to 90°C, freeze protection to −46°C, and a density that prevents the precipitated polymer from settling and is fairly stable to UV degradation. A significantly smaller heat gain is achieved through the clear/cloud glazing when compared to a normal double‐pane window. © 1994 John Wiley & Sons, Inc.
Photoinitiated graft copolymerization of glycidyl methacrylate and 2‐hydroxyethyl methacrylate onto polyacrylonitrile and application of the synthesized graft copolymers in penicillin–amidase immobilization
Authors: Pashova V. S. , Georgiev G. S. , Dakov V. A. 
Published: April 2003

AbstractThe photoinitiated graft copolymerization of hydroxyethyl methacrylate and/or glycidyl methacrylate onto polyacrylonitrile (PAN) and the applicability of the matrices synthesized in this way for penicillin–amidase immobilization are discussed. The copolymers are prepared by putting irradiated PAN fibers with preliminary adsorbed benzophenone on them into the polymerization feed that includes hydroxyethyl methacrylate and/or glycidyl methacrylate dissolved in a water–methyl ethyl ketone mixture. The degree of grafting varies between 11.7 and 46.0%, and its efficiency, between 27.8 and 78.9%. The concentration of epoxy groups in the synthesized copolymers is in the range between 210 and 2220 μmol/g. The reactivity ratios of the two comonomers are determined to be rGM = 0.70 ± 0.15 and rHEMA = 2.73 ± 0.14. The grafted copolymers containing HEMA units provide milder conditions for penicillin–amidase covalent binding. The optimum pH and temperature values of penicillin–amidase immobilized on these matrices are 7.5 and 45°C, respectively. © 1994 John Wiley & Sons, Inc.
Dynamics of solvent diffusion in an aromatic polyimide
Authors: Moon Yoon Duk , Lee Young Moo 
Published: April 2003

AbstractDiffusion behaviors of two polyimides (PIs) synthesized from 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride (BTDA), 4,4′‐oxydianiline (ODA), and 4,4′‐diaminodiphenylsulfone (DDS) were investigated by the gravimetric method. The weight uptake of penetrants (solvents) was nearly proportional to the exposure time in solvent. This phenomenon was considered as the Case II diffusion (non‐Fickian) mechanism. Two PI films had an affinity to N‐methyl‐2‐pyrrolidinone (NMP) rather than to dimethylsulfoxide (DMSO). The solubility parameter differences between two polyimides and NMP are less than 5, whereas that between polyimides and DMSO are greater than 5, as calculated by Hoy's group contribution method. The solvent uptake of anisotropic films contributed to an increase in the thickness. The swollen amount of anisotropic films increased with the swelling temperature but tended to decrease with the imide content and the thickness of the anisotropic films. Isotropic films of two PIs did not swell in both NMP and DMSO. © 1994 John Wiley & Sons, Inc.
Copolyesters. VII. Thermal transitions of poly(butylene terephthalate‐co‐isophthalate‐co‐adipate)s
Authors: Chang Shinn‐Jen , Tsai Hong‐Bing 
Published: April 2003

AbstractThe copolyesters of 1,4‐butanediol, terephthalic acid, isophthalic acid, and adipic acid with different compositions were prepared by melt polycondensation. The intrinisic viscosity of the copolyesters was controlled to be about 0.7–1.0 dL/g. Their second‐run thermal properties were determined by DSC. The composition was found to be a major factor in the determination of the thermal transitions. The effect of the composition on the glass transition temperature and melt transition temperature was interesting. The glass transition temperature was found to be dependent mainly on the content of adipic acid. As the content of adipic acid increased, the glass transition decreased. When the content of terephthalic acid was not less than 35 mol % based on the total diacid monomers, the melting temperature was dependent mainly on the content of terephtalic acid and increased with incrase of the content of terephthalic acid. When the content of terephthalic acid was less than 35 mol %, the melt temperature of the copolyesters did not follow a simple rule. However, the effect of the composition on their melting enthalpy showed no simple trend. © 1994 John Wiley & Sons, Inc.
Specialty polymeric membranes 3. Pervaporation separation of acetic acid/water mixtures through polymeric membranes having a pyridine moiety as a side group
Authors: Yoshikawa Masakazu , Kuno Shin‐Ichi , Kitao Toshio 
Published: April 2003

AbstractPervaporation of an acetic acid/water mixture was studied through synthetic polymeric membranes made from poly(1‐butyl methacrylate), poly(2‐ethylhexyl methacrylate), polystyrene, and copolymers of 4‐vinylpyridine and styrene, whose mole fraction of 4‐vinylpyridine was 0.028 or 0.050. Permselectivities through polystyrene and poly(4‐vinylpyridine‐co‐styrene) (mole fraction of 4‐vinylpyridine, 0.050) are discussed based on the solution‐diffusion theory. © 1994 John Wiley & Sons, Inc.
Electrical behavior of carbon black‐filled polymer composites: Effect of interaction between filler and matrix
Authors: Tang H. , Liu Z. Y. , Piao J. H. , Chen X. F. , Lou Y. X. , Li S. H. 
Published: April 2003

AbstractThe effect of interaction between carbon black and polymer on electrical behavior was studied using the ESR method. The polymer matrices used were HDPE, LDPE, and ethylene/vinyl acetate (EVA). Two kinds of carbon blacks (CB), high structure CSF‐III and low structure FEF, were used as a conductive filler. Compared to that of the HDPE/FEF compound, the positive temperature coefficient (PTC) intensity is lower and electrical reproducibility is worse for the HDPE/CSF‐III compound; however, it can be improved significantly by radiation cross‐linking. On the other hand, the cross‐linking has no practical effect on the PTC intensity of the LDPE/CSF‐III compound while it can be achieved by mixing the compound for a longer time. The great PTC intensity was obtained in the HDPE/EVA/CSF‐III compound, and it is greater than that of HDPE/CSF‐III or EVA/CSF‐III. We explain these results using the concept of interaction between the filler and matrix. The absorption of the polymer on the carbon black surface may be physical or chemical; the latter is caused by the free‐radical reaction between the polymer and carbon black, and it can occur during the radiation or preparation process of the compound. These “bound polymers” are essentially important for materials to have a great PTC intensity and good reproducibility. © 1994 John Wiley & Sons, Inc.