bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of compatibility on heat capacity of molten polyblends
Authors: Wang Y. Z. , Hsieh K. H. , Chen L. W. , Tseng H. C. 
Published: April 2003

AbstractThe heat capacity and phase relation of polymer blends consisting of two homopolymers or a homopolymer with a block copolymer have been investigated by differential scanning calorimetry (DSC). Polystyrene (PS) and polybutadiene (BR) are the two homopolymers, while the styrene–butadiene–styrene (SBS) copolymer is employed as the block copolymer in this study. The heat capacity and specific volume of the PS and BR homopolymers increase with increasing temperature at a constant pressure. The heat capacity of styrenebutadiene (SBR) random copolymer, which is considered a miscible system, can be calculated by an additive rule from the addition of the styrene and butadiene segment number fractions in the random copolymer multiplied by the corresponding heat capacity of PS and BR homopolymers. However, the heat capacity of the immiscible system of the SBS triblock copolymer can be estimated by the addition of the two segment number fractions multiplied by the reciprocal of the corresponding heat capacity of the PS and BR homopolymers. The thermal and dynamic mechanical analysis data of the polyblend from the two PS and BR homopolymers both show a low degree of miscibility. A saturated solubility of the homopolymer dissolved in the SBS block copolymer is proposed and the purification of the styrene and butadiene phases in the SBS copolymer is observed as it blends with either PS or BR homopolymer. The heat capacity of polymer blends composed of two phases obey the principle of additivity from the weight fractions of the heat capacity of the corresponding individual phase. © 1993 John Wiley & Sons, Inc.
Mechanical properties of PET short fiber–polyester thermoplastic elastomer composites
Authors: Guo Wuyun , Ashida Michio 
Published: April 2003

AbstractPresented in this paper is the investigation of the mechanical properties of PET short fiber‐polyester thermoplastic elastomer (Hytrel) composites and the discussion of the short fiber reinforcement of the composites. Excellent adhesion of PET fiber to Hytrel elastomer was obtained by treating with isocyanate in toluene solution. The Hytrel composites filled with treated fiber showed a similar tensile behavior, with higher values, to that for the matrix elastomer when fiber loading was less than 5 vol %. The composites loading fibers more than 5 vol % displayed an obvious yield phenomenon, and their yield elongation (between 30–40%) was greater than the fiber's break elongation, which suggested that extensibility of the fiber was quite different from that of the matrix. It is considered that the reinforcement of the short fiber mainly depends on the difference of extensibility between the fiber and the matrix because the difference directly affects the effective transference of the stress from matrix to fiber. The modified parallel model for Young's modulus and yield strength of the composite can be given by the following equations:

and

respectively, through introducing two effective deformation coefficients, α and β, to represent the extensibility of the fiber and the matrix respectively. The α obtained from the experimental results did not depend on fiber loading but increased with increasing fiber length, and the α for Young's modulus was larger than the one for yield strength, which suggests that α is a function of the strain of the composite and may decrease with increasing the strain, namely, the deformation difference between the fiber and the matrix increases when the strain increases. On the other hand, β is a function of α as:

For the Hytrel elastomer, the maximum of each succeeding stress–strain cycle coincided with the original stress–strain curve for elongations under 600%, but for the Hytrel composites such coincidence was limited to elongations under 30%. This may be caused by the reforming of crystallites in the stress‐softened Hytrel elastomer phase at high strain. © 1993 John Wiley & Sons, Inc.
Volatile compounds extracted from polypropylene sheets by hot water: Influence of the temperature of sheets injection
Authors: Rebeyrolle‐Bernard P. , Etiévant P. 
Published: April 2003

AbstractThe influence of the formulation of polypropylene (PP) on the organoleptic properties of the foodstuff in contact is of great importance for the quality of the product. A study was made on PP pellets degraded and not degraded and pointed out the presence and olfactive importance of volatile components extracted from PP pellets by hot water. Plastic packaging materials correspond to a further step of manufacturing: the injection step, and this is often conducted at high temperature. PP (not degraded) and PP‐CR (degraded) were transformed into sheets at several temperatures; Lickens–Nickerson extracts were made and allowed the quantification of volatile compounds already identified. A statistical analysis showed that temperature was a very significant parameter. An increasing injection temperature (275 or 300°C) creates increasing quantities of volatiles. This was well correlated with the sensory analysis made on the organic extracts of the sheets and also directly on molded cups. © 1993 John Wiley & Sons, Inc.
Native celluloses on the basis of two crystalline phase (Iα/Iβ) system
Authors: Wada Masahisa , Sugiyama Junji , Okano Takeshi 
Published: April 2003

AbstractA survey by X‐ray diffractometry was carried out to confirm the two crystalline phase Iα/Iβ(triclinic/monoclinic) system of native celluloses. We have investigated cellulose samples from 12 different origins and measured the d‐spacings with reasonable precision. The samples were then subjected to the hydrothermal annealing that brings the cellulose crystals to the monoclinic type; d‐spacings were reevaluated afterward. From the statistical analysis using observed d‐spacings, all the cellulose samples were categorized into the two groups that coincide with the two crystalline phase systems: one is the algal‐bacterial type rich in triclinic phase and the other is the cotton‐ramie type of the monoclinic phase. © 1993 John Wiley & Sons, Inc.
IR studies of wood plastic composites
Authors: Khan Mubarak A. , Ali K. M. Idriss , Basu Subhash. C. 
Published: April 2003

AbstractWood plastic composites (WPC) of simul were prepared by gamma radiation using butylacrylate (BA) and methylmethacrylate (MMA) as the monomer and methanol as the swelling agent at 9:1 (v/v) ratio. IR spectra of simul, bulk polymer of BA (or MMA) film, and WPC of different polymer loadings ranging from 18 to 115% were studied. Increase of the characteristic peak intensity at 1735 cm−1 (CO vibration for acetyl groups) over that of 1620 cm−1 (conjugated aryl carbonyl groups) along with the increase of polymer loading of simul with the monomer indicates that the graft copolymerization took place between the monomer and the simul wood matrix. © 1993 John Wiley & Sons, Inc.
Thermal behavior of ungrafted and grafted bagasse and wood pulps
Authors: Kessira L. , Ricard A. 
Published: April 2003

AbstractThe effect of grafting of methyl methacrylate (MMA) and acrylonitrile (AN) on the thermal behavior of the pulp of sugar cane loaded with CaCO3 and the pulp of a broad‐leaved tree has been studied by thermal methods. Different experimental conditions of grafting AN onto the eucalyptus pulp have been used, including both water and organic solvent systems as the medium of reaction. To optimize the grafting of MMA onto wood pulp, the effect of pulp swelling and the contact time of the monomer with the pulp have been examined. Ungrafted as well as grafted cellulose samples with different levels of grafting were characterized by differential scanning calorimetry (DSC) and the thermogravimetric analysis (TGA). The CaCO3 filler makes the pulp of bagasse thermally more stable. The grafting of MMA onto the bagasse or the wood pulps improves their thermal stability. This is not the case for wood grafted with poly(AN). The thermal stability of the grafted and ungrafted samples varies after a few weight percent has been lost. The glass transition temperature (Tg) of the copolymers have been measured and they are in good agreement with the calculated data. © 1993 John Wiley & Sons, Inc.
Determination of PEG concentration in its aqueous solution using differential scanning calorimetry
Authors: Yamauchi T. , Hasegawa A. 
Published: April 2003

AbstractThe Freezing and melting behavior of aqueous poly(ethylene glycol) (PEG) solutions up to a concentration of 10% was examined using DSC. So long as the molecular weight of PEG is over 1000, the cooling and heating DSC curves have two peaks, which are attributed to freezable bound water and free water. The amounts of freezable bound water and nonfreezing water linearly increase with an increase of PEG concentration. Therefore, a method using DSC was proposed for determining the concentration of aqueous PEG solutions. Although PEG concentration can be determined by the heat of freezable bound water, the ratio of heat of freezable bound water to heat of free water is a better way to determine the concentration. © 1993 John Wiley & Sons, Inc.
Skin and layer formation in films prepared from carbohydrates, poly(ethylene‐co‐acrylic acid), and polyethylene
Authors: Swanson C. L. , Fanta G. F. , Salch J. H. 
Published: April 2003

AbstractCornstarch, a canary dextrin, and a maltodextrin were compared in films blown from carbohydrates compounded with poly(ethylene‐co‐acrylic acid) (EAA), low‐density polyethylene (LDPE), and aqueous ammonium hydroxide plasticizer. Dextrins or maltodextrins having dextrose equivalent values of one and greater caused dark‐colored films with caramel odors, probably due to Maillard reactions. Blown films with hydrophobic skins and water sensitive cores were produced with the dextrinized carbohydrates, but not from natural cornstarch. Water sensitivity of films containing the dextrinized carbohydrate was reduced by recycling the films through the blown film die. A mechanism for development of the skins is proposed, as is a method for preparing thin semipermeable membranes. © 1993 John Wiley & Sons, Inc.This article is a US Government work and, as such, is in the public domain in the United States of America.
Multifunctional epoxy resins
Authors: Choudhary Veena , Agarwal Seema , Varma I. K. 
Published: April 2003

AbstractThe curing behavior of epoxy resins prepared by reacting epichlorohydrin with 4,4′‐diaminodiphenyl methane (DADPM)/4,4′‐diaminodiphenyl ether (DADPE) or 4,4′‐diaminodiphenyl sulfone (DDS) was investigated using DDS and tris‐(m‐aminophenyl)phosphine oxide (TAP) as curing agents. A broad exothermic transition with two maxima were observed in the temperature range of 100–315°C when TAP was used as the curing agent. The effect of varying DDS concentration on curing behavior of epoxy resin was also investigated. Peak exotherm temperature (Texo) decreased with increasing concentration of DDS, whereas heat of curing (ΔH) increased with an increase in amine concentration up to an optimum value and then decreased. Thermal stability of the resins, cured isothermally at 200°C for 3 h, was investigated using thermogravimetric analysis in a nitrogen atmosphere. Glass fiber‐reinforced multifunctional epoxy resin laminates were fabricated and the mechanical properties were evaluated. © 1993 John Wiley & Sons, Inc.
Photocross‐linking of low‐density polyethylene. III. Supermolecular structure studied by SALS
Authors: Qu Bao Jun , Rånby Bengt 
Published: April 2003

AbstractThe supermolecular structure of photocross‐linked polyethylene (XLPE) has been studied by small‐angle light scattering (SALS). The data show that the spherulitic structure of XLPE gradually deteriorates with increasing degree of cross‐linking and increasing irradiation temperature from well‐developed spherulites to rodlike aggregates and disordered lamellar structures. A photocross‐linked sample of PE has lower crystallinity, smaller crystallites, and smaller spherulites than does the original sample. At high degrees of cross‐linking, the SALS patterns show little or no spherulitic structure. Results with photocross‐linked polyethylene demonstrate that the overall effect of cross‐linking on the morphological structure is similar to that of an increase in molecular weight of the polymer. © 1993 John Wiley & Sons, Inc.
Spin probe studies of nonsolvent penetration into polymer particle formed from poly(vinyl acetate) and poly(2‐ethylhexyl methacrylate)
Authors: Pekcan Önder , Demir Yusuf 
Published: April 2003

AbstractNonaqueous dispersion (NAD) of poly(vinyl acetate) (PVAc) particles sterically stabilized by poly(2‐ethylhexyl methacrylate) were examined by ESR spectroscopy after introduction of a trace quantity of a spin probe, 3‐carbomoyl‐2,2,5,5‐tetramethyl 3‐pyrolin‐1‐yloxy. ESR spectra were monitored as a function of temperature from ‐160 to 100°C. In spite of the complex morphology of the particle, it is found that the behavior of the probe in the NAD was essentially identical to that in a pure PVAc matrix. Solvent penetration into (NAD) particles were studied. These colloidal particles were exposed to a dilute solution of the spin probe, and the bimodal distribution of the ESR spectra of this probe molecule were carefully monitored as a function of time. Fickian‐type diffusion of spin probes into the particles was observed and a spherical model was employed to obtain the diffusion coefficients (D) in various solvents. D values were found around 10–15 cm2/s and were interpreted as the parameter, inversely proportional to the apparent viscosity of the environment inside the PVAc particle. The maximum amount of diffused solvent molecules (M∞) into the PVAc particle was found inversely proportional to polymer‐solvent interaction through the solubility parameters. © 1993 John Wiley & Sons, Inc.
Silane‐modified polyvinylimidazole(1) for corrosion protection on copper at elevated temperatures
Authors: Jang Jyongsik , Ishida Hatsuo 
Published: April 2003

AbstractSilane‐modified N‐polyvinylimidazole [PVI(1)] copolymers have been synthesized from various mole ratios of γ‐methacryloxypropyltrimethoxysilane (γ‐MPS) and N‐vinylimidazole, VI(1). Fourier transform infrared reflection‐absorption spectroscopy (FTIR‐RAS) is used to investigate the modified PVI(1) on copper surfaces. The silane‐modified PVI(1) has good corrosion protection and adhesion promotion capabilities for copper substrate under severe environments. The relationship between coating thickness and corrosion protection is studied at elevated temperatures. The relationship between the mole ratio of comonomers and the corrosion processes of a copper surface has also been investigated at elevated temperatures. The corrosion protection improves drastically with increased VI(1) content. An adhesion study of the silane‐modified PVI(1) film on a copper surface is also carried out using the ASTM adhesive tape test. From the adhesion strengths between the modified PVI(1) films and copper surface, it has been observed that modified PVI(1) acts as an adhesion promoter and does not depend on the mole ratio of γ‐MPS/VI(1) within the range of this experiment. Good adhesion of an anticorrosion coating is important for the corrosion protection of a copper surface. © 1993 John Wiley & Sons, Inc.
Selective hydrogenation of olefinic bonds in styrene‐isoprene‐styrene triblock copolymer by palladium acetate catalyst
Authors: Bhattacharjee Susmita , Rajagopalan Padmavathy , Bhowmick Anil K. , Avasthi Bhola Nath 
Published: April 2003

AbstractHomogeneous catalytic hydrogenation of styrene‐isoprene‐styrene triblock copolymer (SIS) has been carried out selectively at the carbon‐carbon double bond in the presence of palladium acetate catalyst under mild conditions. Degree of hydrogenation has been calculated with the help of infrared and nuclear magnetic resonance spectroscopic techniques. Almost 90 mol % complete hydrogenation has been achieved at 60°C under 1.4 MPa hydrogen pressure, 40 mg catalyst (for 2 g of polymer) in chloroform‐acetone solution for 1 h. © 1993 John Wiley & Sons, Inc.
Low loss HEMA/EMA copolymer waveguides with a range of wetting and optical properties
Authors: Walker D. S. , Balasubramanian K. , Reichert W. M. 
Published: April 2003

AbstractHomopolymers and copolymers of optical grade hydroxyethyl methacryiate (HEMA) and ethyl methacrylate (EMA) were synthesized with bulk copolymer compositions of 0, 10, 43, 75, 86, 89, and 100 mol % HEMA. Attenuated total reflection IR (ATR‐IR) and X‐ray photoelectron (XPS) spectroscopies showed an unhydrated surface composition that varied insignificantly from the bulk. Polymer surface wettability, percent swelling of the copolymers in water, and the bulk refractive index increased with increasing HEMA content. High‐quality thin‐film integrated optical waveguides (IOW) were spun cast from copolymer solutions with propagation losses of < 1 dB/cm. Waveguide refractive indices determined from coupling angle measurements agreed closely with the bulk measurements. These results show that HEMA/EMA copolymers that form transparent films produce polymer IOWs with a range of bulk swellabilities, surface wettabilities, and optical densities. © 1993 John Wiley & Sons, Inc.
Acoustic behaviour of chromium soap solutions in benzene–dimethyl formamide mixture
Authors: Mehrotra K. N. , Jain Mamta 
Published: April 2003

AbstractThe critical micelle concentration and various acoustic parameters of chromium soaps (myristate, palmitate, and stearate) in a mixture of benzene and dimethyl formamide (4 : 1 v/v) have been determined by ultrasonic velocity measurements. The results showed that the ultrasonic velocity, specific acoustic impedance, molar sound velocity, and molar sound compressibility increase, while intermolecular freelength, adiabatic compressibility, and available volume decrease with increasing concentration and chain length of the soap. The results show that there is a significant interaction between soap and solvent molecules in dilute solutions and the soap molecules do not aggregate appreciably in dilute solutions. © 1993 John Wiley & Sons, Inc.
Synthesis and curing behavior of diimide–diacid‐modified saturated polyester
Authors: Lee Wen‐Fu , Chen Ienwhei , Chang Chi‐Hong 
Published: April 2003

AbstractThe polyester and diimide–diacid‐modified polyester prepolymer have been synthesized with different molecular weights through melt polycondensation of 1, 6‐hexanediol (HD), trimethylol propane (TMP), isophthalic acid (IPA), diimide diacid, and phthalic anhydride (PA) at various molar ratios. The prepolymers were then mixed with an equivalent phenol‐blocked TDI and /or HMDI in m‐cresol in deriving the polyester urethane varnishes. The degree of crosslinkage and thermal behavior have been investigated here. © 1993 John Wiley & Sons, Inc.
Monosize polystyrene microbeads by dispersion polymerization
Authors: Tuncel Ali , Kahraman Ridvan , Pişkin Erhan 
Published: April 2003

AbstractMonosize Polystyrene microbeads were prepared by dispersion polymerization in different alcohol/ water media. Azobisisobutyronitrile and polyacrylic acid were utilized as initiator and steric stabilizer, respectively. The polymerizations were performed in three kinds of dispersion media having different polarities: isopropanol/water, 1‐butanol/water, and 2‐butanol/water. The effects of initiator and stabilizer concentrations, alcohol/water ratio, and monomer/dispersion medium ratio on the size and monodispersity of the polymeric microbeads were investigated. By dispersion polymerization, polystyrene (PS) microbeads were obtained in the size range of 1.0–4.0 μm with narrow size distribution or in the monosize form. The average size and size distribution of microbeads with increasing polarity of the dispersion medium. The average size and size distribution increased with increasing initiator concentration in all dispersion media. The increase in the stabilizer concentration in homogeneous dispersion media resulted in a decrease in average size and size distribution of the microbeads. A clear increase was observed in the average size with increasing monomer/dispersion medium ratio. Isopropanol/water dispersion medium provided monosize microbeads with higher values of monomer/dispersion medium ratio. © 1993 John Wiley & Sons, Inc.
Molecular weight dependence of the heats of hydration of some oligomeric ethylene oxides and their methoxyl derivatives
Authors: Rowe R. C. , Mckillop A. G. 
Published: April 2003

AbstractThe molecular weight dependence of the heat of hydration of the oligomeric ethylene oxides and their monomethoxyl and dimethoxyl derivatives has been studies using microcalorimetry. In all cases the molar heat of hydration decreased rapidly at low molecular weights reaching an asymptote at molecular weights in excess of 400. Equivalent values were obtained between oligomers and blends of the same average molecular weight. The data followed the Flory relationship relating the property of a polymer to the reciprocal of its molecular weight. However, the gradient for the oligomeric ethylene oxides was different from that of the two methoxyl derivatives suggesting a change in chain configuration. © 1993 John Wiley & Sons, Inc.
A stepwise scheme for the calculation of molecular weight distribution in condensation polymers. II. Scheme for bimolecular condensation polymers
Authors: Tung L. H. 
Published: April 2003

AbstractA stepwise scheme, reported recently for the calculation of molecular weight distributions in AB monomolecular condensation polymers under the condition of unequal reactivity, has been applied to the more common AA, BB bimolecular condensation polymers. In the scheme a condensation polymerization is arbitrarily subdivided into a number of steps. The polymer obtained in one step is treated as the monomer for the next step. In each of the steps, Flory's distribution for condensation polymer under equal reactivity is used as the molecular weight distribution for that step. Reactivity variances are incorporated into the calculation through the application of weighing factors on the concentrations of the reacting molecules in each of the steps. In the bimolecular case, three types of monomers, AA, BB, and AB, must be considered for the intermediate polymerization steps. The required distribution of this trimolecular condensation under equal reactivity conditions is not available and has to be derived. As expected, the application of the scheme to bimolecular condensation is more complex but numerical calculations using the scheme should still be manageable on a desktop computer with suitable memory capacity. © 1993 John Wiley & Sons, Inc.
Polyamic acids: Thermal and microwave imidization and film properties
Authors: Kishanprasad V. S. , Gedam P. H. 
Published: April 2003

AbstractPolyamic acids were synthesized from benzophenonetetracarboxylic dianhydride and di‐amines, viz., 4,4′ ‐diaminodiphenymmethane and 4,4′ ‐diaminodiphenyl ether. The course of imidization of the polyamic acids both by thermal and microwave treatments was tracked by infrared spectroscopy. The mechanical properties, namely the tensile strength and toughness of the films of polyimides with varying degree of imidization obtained by the two treatments were compared. The effect of degree of imidization of polyimide coatings on adhesion to copper substrate was also studied. Nearly 100% imidization was achieved by the thermal process, whereas the maximum imidization that could be achieved by the microwave process was about 50%. In thermal imidization, the adhesion values of the coatings slowly increased, attaining a maximum value at 80% imidization, after which there was a decrease in adhesion. © 1993 John Wiley & Sons, Inc.