bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamic measurement of interfilament friction on staple yarns
Authors: Murayama Takayuki 
Published: April 2003

AbstractA new method is presented which permits the quantitative characterization of interfilament friction of staple yarns using loss tangent tanδ data measured directly from samples nondestructively with the Rheovibron DDV‐II viscoelastometer. The procedure is derived from a phenomenological model of the structure's mechanical behavior in which its energy dissipation capacity consists of both filament internal viscous friction and a filament‐to‐filament coulomb friction mechanism. By treating the coulomb dissipation in terms of an additional effective viscous component, the loss tangent of the model representing the structure can be analytically expressed in terms of the internal filament viscous properties, a fiber‐to‐fiber coulomb parameter, and an undetermined assembly dispersion factor which is representative of strength. By measuring effective loss tangent data for the staple yarn and a constituent filament at two separate frequencies and considering the magnitude of the coulomb mechanism to be independent of the test frequency in the range employed, both the coulomb friction dissipation and the assembly dispersion factor can be quantified. Using this procedure, loss tangent data from tests on a series of staple yarns (nylon, polyester, and acrylic fiber) are used to calculate both assembly dispersion and interfilament coulomb friction factors.
Tributylborane‐initiated grafting of methyl methacrylate onto chitin
Authors: Kojima Kuniharu , Yoshikuni Masako , Suzuki Tominori 
Published: April 2003

AbstractThe grafting of methyl methacrylate (MMA) onto chitin initiated by tributylborane (TBB) was investigated at ordinary temperature. It was found that water was essential to the grafting. No grafting was observed in the usual organic solvents such as n‐hexane, tetrahydrofuran, and cyclohexanone. The total conversion and the percentage and efficiency of grafting increased with increasing chitin content. The extent of homopolymer formation also increased with increasing chitin content. The optimum concentrations of TBB and MMA for the grafting were determined. Activation energies were estimated to be about 22.8 and 27.4 kcal/mole for the grafting and homopolymerization, respectively. On the basis of these results the mechanism of the grafting onto chitin was discussed.
Branching by copolymerization of monovinyl and divinyl monomers in continuous‐flow stirred reactors
Authors: Strate G. Ver , Cozewith C. , Graessley W. W. 
Published: April 2003

AbstractThe effect on molecular weight distribution of copolymerization with divinyl monomers, which leads to branch points in an otherwise linear polymer, is calculated for a continuous‐flow stirred reactor. It is found that steady state operation of the reactor becomes impossible at a degree of branching equal to only half that which causes gellation in a batch reactor. In steady state operation the ratio of weight to number average degree of polymerization cannot exceed 7, this ratio being 2 in the absence of branching. The classical result that the fraction of mers coupled at the gel point is 1/(D̄Pw)o, where (D̄Pw)o is the weight‐average degree of polymerization without branching, does not apply in a CFSR at any steady state conversion. Such deviations appear in batch reactions only when gelation occurs at high conversions.
Shear degradation of poly(vinyl acetate) in toluene solutions by high‐speed stirring
Authors: Agarwal S. H. , Porter Roger S. 
Published: April 2003

AbstractA poly(vinyl acetate) (PVAc) of M̄w 750,000 and M̄w/M̄n 5.10 in toluene solution was sheared in a Virtis‐60 homogenizer. The polymer concentration was 3.0 to 12.0 g/100ml, and test temperature was 10 ± 0.5°C. The extent of degradation was measured by gel permeation chromatography (GPC). It was concluded that on shearing (i) the molecular weight decreases rapidly at the beginning of shearing and thereafter decreases ever more slowly toward a limiting value, (ii) the molecular weight distribution is narrowed, (iii) no degradation occurs up to 5000 rpm and thereafter increases with stirring speed, (iv) degradation is more at lower concentrations but concentration is not a sensitive variable, and (v) the chain scission occurs randomly. The Mark‐Houwing relationship for PVAc in THF at 25°C was derived as [η] = 2.47 × 10−4 × M̄v0.644.
Pyrolysis and combustion of cellulose. VII. Thermal analysis of the phosphorylation of cellulose and model carbohydrates during pyrolsis in the presence of aromatic phosphates and phosphoramides
Authors: Langley J. T. , Drews M. J. , Barker R. H. 
Published: April 2003

AbstractThermal gravimetric analysis, differential scanning calorimetry, and derivative thermal gravimetric analysis were utilized to characterize the thermal interactions between cellulose, 1‐6, anhydro β‐D‐glucopyranoside, and D‐glucose and model phosphate and phosphoramide flame retardants. The phosphoramides induced higher char yields than the phosphates during the pyrolysis of the mixtures of carbohydrates and organophosphorus compounds. Exothermic reactions attributed to phosphorylation and char formation were observed with each of the phosphoramide/carbohydrate mixtures and were absent with the phosphates. The individual phosphorus compounds studied showed similar thermal behavior with each of the carbohydrates indicating that the mode of interaction for these mixtures was similar. Isothermal gravimetric analysis of the organophosphorus/carbohydrate mixtures was used to measure the rate of decomposition weight loss from isothermal conditions. This weight loss was used as an indication of rate of fuel formation. The kinetics observed for these measurements indicated that the phosphoramide mixtures underwent a rapid weight loss to a final char with an effective Eact of about 55 kcal/mol while the phosphate mixtures exhibited effective Eact′s for decomposition lower than those observed for the pure carbohydrates. Mixtures of glucose with selcted arylphosphoramide esters were pyrolysed in order to determine the effect of lability of the leaving group on char formation. Gas chromatographic analysis of the pyrolysis products indicated that phenol was the favored leaving group in comparison with aniline units, but char promotion appeared to be dependent on the number of P‐N bonds present in the original phosphoramide. Electron spectroscopy for chemical analysis indicated that chemically similar chars were obtained from the different organophosphorus/carbohydrate combinations.
Radiation‐induced graft copolymerization of methyl methacrylate on natural and modified wool. V. Crystalline and morphological structure
Authors: Varma D. S. , Sadhir R. K. 
Published: April 2003

AbstractX‐ray diffraction patterns of the α‐ and β‐crystalline phases of natural, chemically modified, and MMA‐grafted wool fibers were investigated. In the grafted fibers variation of the equatorial and meridional scattering intensity during the α–β transformation was inhibited. This indicated that the grafting had stabilized the structure to the α–β transformation. The average crystallite size was found to increase with the extent of grafting, and the degree of orientation appeared to decrease with percent graft‐on. SEM studies revealed little damage to the surface topography of wool fibers after chemical treatments. Graft copolymerization with MMA made the fiber surface regular and smooth, mainly because of deposition of polymer in the escarpment, thus reducing the sharpness of the scaly structure. Scanning electron micrographs of the peeled‐off surface and cross sections of the grafted fibers indicated that a significant amount of polymer was deposited in the medullae of the fibers.
Shear flow rheological properties, fiber damage, and mastication characteristics of aramid‐, glass‐, and cellulose‐fiber‐reinforced polystyrene melts
Authors: Czarnecki Lech , White James L. 
Published: April 2003

AbstractAn experimental study of the viscosity and principal normal stress difference of a polystyrene melt filled with aramid (Kevlar), glass, and cellulose fibers is reported. The influence of loading level and mastication on the rheological properties is discussed. The effects of mixing and mastication on fiber damage are considered. Glass fibers break down rapidly to very small aspect ratios, while aramid shows a “kinked” structure, with kinks occurring every 100 μm. A mechanism is proposed for fiber breakage based on buckling during rotation in shear flow. It is found that addition of fibers increases the viscosity in the same manner as a reduction in temperature, and data may be superposed by reduced plotting. This indicates that the viscosity increase is due solely to enhanced viscous dissipation in the matrix and not to interparticle forces as is the case with smaller particles. The principal normal stress difference increases at fixed shear stress with fiber loading. The extent of increase depends upon fiber loading, aspect ratio, and modulus.
Polymerization from the vapor phase. I. Poly(p‐phenyleneterephthalamide) gas barrier coatings
Authors: Ikeda R. M. , Angelo R. J. , Boettcher F. P. , Blomberg R. N. , Samuels M. R. 
Published: April 2003

AbstractAn atmospheric‐pressure, vapor‐phase polymerization technique was used to deposit thin(1–10 μm) poly(p‐phenyleneterephthalamide) coatings onto polyester film and other sheet substrates. A minimum deposition temperature of 170°C, was found to be critical. When substrate temperatures were below 170°C, coatings were loosely adhered, powdery, and of low molecular weight; above 170°C, coherent, well‐adhered, high molecular weight coatings were obtained. These vapor‐deposited coatings exhibited exceptionally good oxygen barrier properties and were found to consist of fused 0.1‐μm particulates. Scanning electron microscopy (SEM) of the top surfaces of these coatings clearly revealed their particulate origin. Similar evidence was also obtained from SEM examination of fracture surfaces and transmission electron microscopy of microtomed sections. The coalescence of these coatings was demonstrated by SEM of plasma‐etched surfaces and oxygen permeability information. The uniplanar orientation of the polymer crystals in these multiparticulate coatings was strong evidence for the epitaxial growth of the crystals.
Relation between intrinsic viscosity and molecular weight
Authors: Quackenbos H. M. 
Published: April 2003

AbstractThe connection between intrinsic viscosity and number‐average and weight‐average molecular weight has been revealed by calculations from distribution curves. Log‐normal distributions, and moderate variations thereon, were chosen as typical for polystyrene and other thermoplastics. Intrinsic viscosity and number‐average molecular weight are unlikely to be related because of the highly disturbing effect of small variations in molecular weight distribution. Conversely, intrinsic viscosity is a good practical measure of weight‐average molecular weight up to a ratio of 10 for weight‐to‐number average.
Improvement of flame‐retardant properties of insulated wires by radiation crosslinking
Authors: Hagiwara Miyuki , Sohara Masayoshi , Araki Kunio , Kagiya Tsutomu 
Published: April 2003

AbstractElectric wires coated with polyethylene insulation crosslinked by a chemical method (gel fraction = 80%) and a jacket of self‐extinguishing resin were produced. The jacket was crosslinked by irradiation with γ rays or accelerated electrons. Flame retardant properties of the wire improved by γ‐ray induced crosslinking up to ∼60% gel fraction in the jacket. Beyond this point, however, the flame resistance rapidly decreased with increasing gel fraction. The flame resistance was also improved by irradiation with electrons, but the extent of the improvement was strongly dependent on the energy of incident electrons. This fact was attributed to the difference in the distribution of energy dissipation, i.e., crosslinks formed in the jacket. By introducing a double layer structure to the jacket, in which the inner layer adjacent to the polyethylene insulation was crosslinked more densely than the outer layer, the wires were markedly improved in resistance to flame and heat deformation.
Tensile properties and morphology of blends of polyethylene and polypropylene
Authors: Lovinger Andrew J. , Williams M. L. 
Published: April 2003

AbstractThe tensile behavior of blends of linear polyethylene (PE) and isotactic polypropylene (PP) was examined in relation to their morphology. Yield stress increases monotonically with increasing PP content, while true ultimate strength is much lower in all blends than in the pure polymers as a result of early fracture. The blends fail at low elongation because of their two‐phase structure, consisting of interpenetrating networks or of islands of PE in a PP matrix, as shown by scanning electron microscopy of fracture surfaces and transmission electron microscopy of thin films. While spherulites in PP are very large (∼100 μm in diameter), addition of 10% or more of PE drastically reduces their average size. This, together with the profusion of intercrystalline links introduced by PE, may be associated with maximization of tensile modulus in blends containing ∼80% PP. Introduction of special nucleating agents to PP reduces average spherulite size and is accompanied by slight improvements in modulus. Thin films of blends strained in the electron microscope neck and fibrillate in their PE regions, but fracture cleanly with little fibrillation in areas of PP.
Quantitative analysis of polymer blends using breadths of overlapping x‐ray diffraction lines
Authors: Chidambareswaran P. K. , Sreenivasan S. , Patil N. B. , Sundaram V. 
Published: April 2003

AbstractA method is developed to estimate the composition of a powder mixture using breadths of over‐lapping x‐ray diffraction (XRD) lines. The application of the method is illustrated for analyzing blends of cotton and jute.
Graft copolymerization of styrene onto cellulose acetate p‐nitrobenzoate by chain transfer reaction
Authors: Nakamura Shigeo , Yoshikawa Eimei , Matsuzaki Kei 
Published: April 2003

AbstractStyrene was grafted onto cellulose acetate p‐nitrobenzoate (CANB) by chain transfer reaction of growing polymer radicals to the pendant nitro groups of CANB. A copolymer with a branch for every 17.2 nitro groups was obtained. This result indicates that the pendant aromatic nitro group is more effective in obtaining a graft copolymer by radical mechanism than pendant double bond on the trunk polymer previously reported, where graft copolymers with a branch for several hundred of double bonds are produced.
Rheological and mechanical properties of polyurethane modified by BHET
Authors: Lin Chen‐Chong , Yang Bin‐Zw 
Published: April 2003

AbstractThe chemical structure of polyurethane modified by BHET is correlated with its mechanical and dynamic mechanical properties. Evaluation of this amorphous elastomer by means of stress–strain tests and transition temperature measurements reveals that incorporation of the BHET structure into the soft polyester segment affects the domain structure and, in turn, the entire mechanical behavior of polyurethane. It is also shown that polyurethane has a wide range of Tg and secondary transition temperature by varying the ratio of BHET to EG as well as the ratio of TDI to polyester polyol.
Crosslinking of partially neutralized carboxyl‐terminated liquid rubbers with bisepoxide and anhydride
Authors: Matsuda Hideaki 
Published: April 2003

AbstractCrosslinking of partially neutralized carboxyl‐terminated liquid rubbers (PNCTLR) with bisepoxide and anhydride was investigated by the PNCTLR–bisepoxide–anhydride reactions. The PNCTLR were prepared, by the partial neutralization with MgO and CaO, from a polymer of butadiene (Hycar CTB 2000X162) and a copolymer of butadiene–acrylonitrile (Hycaṙ CTBN 1300X8). As the bisepoxide, bisphenol‐A diglycidyl ether was used, and hexahydrophthalic anhydride was the anhydride used. It was found that the metal carboxylate groups of PNCTLR catalyze the crosslinking reactions, and, further, the Mg carboxylate group showed higher catalytic activities than the Ca carboxylate group. As for the physical properties of the cured rubbers obtained, the rubbers containing Mg showed higher tensile strength and Shore A hardness than those containing Ca. In addition, the CTBN‐series cured rubbers showed better physical properties than those of the CTB‐series, because of a polarity effect of nitrile groups in the former rubbers. Resistances to water and chemical attack, thermal behavior, and stress relaxation are also discussed.
Dyeing of cotton fibers decrystallized by alkali swelling and partial substitution
Authors: Iyer P. Bhama , Iyer K. R. Krishna , Patil N. B. , Bhatt Indira G. 
Published: April 2003

AbstractThis report summarizes the observations made on the dyeing behavior of highly decrystallized cotton fibers obtained by partial acethylation and cyanoethylation of NaOH swollen fibers. The dyeing studies were also carried out after crosslinking these decrystallized samples. A purified direct dyeing Chlorazol Sky‐Blue FF, has been used for the studies. It is observed that partially cyanoethylated and acetylated celluloses show a dye uptake of more than twice that of the corresponding swollen controls even for low degrees of substitution such as about 5.0% acetyl content for the acetylated fibers and 1.0% nitrogen content for the cyanoethylated fiber. On crosslinking also the trend in the dye uptake pattern remained the same, thought the actual amount of dye the fibers could adsorb was markedly reduced. The swollen, substituted, and crosslinked fibers showed a better uniformity of appearance than the swollen and crosslinked fibers.
Structural transformations during chloromethylation of flexible polystyrene networks
Authors: Belfer Sofia , Glozman Raya , Deshe Abraham , Warshawsky Abraham 
Published: April 2003

AbstractStrong morphologic variations were noted in the chloromethylation of styrene copolymers incorporating TAT or DVB as crosslinking agents. In the first case control over the chloromethylation conditoins (solvent, temperature, time) can be applied in order to mold the final porous structure of the chloromethylated polymer. In the case of XE‐305 containing higher concentration of crosslinking agent, the chloromethylation conditions have a less, but still significant, effect on the structure and functional group distribution of the product. Under conditions of low ratios of chloromethylating agent (CME) or catalyst (SnCl4), the chlorine incorporation figures are medium, but chlorine distribution through the cross section of the bead is more or less homogeneous. Increase in the above ratios results in increased chlorine concentrations, but also in higher degree of secondary crosslinking and uneven chlorine distribution profiles. Preselection of the experimental conditions enables calculated introduction of functional groups. In the case of TAT–styrene copolymers, controlled experimental conditions are used to form a porous structure with low and high chlorine distribution. Such a porous polymer can then be functionalized by other reactions. Under certain chloromethylation conditions, the chloromethylated TAT–styrene copolymer is aminated to produce anion exchange resins, without further morphological changes.
Investigation of the dependence of the infrared absorptivity of a functional moiety on the molecular weight of a homopolymer
Authors: Mirabella Francis M. 
Published: April 2003

AbstractThe subject of this investigation was the determination of the effect of molecular weight (MW) on the infrared absorptivity of a functional moiety in polystyrene homopolymer. It was found that no consistent dependence of infrared absorptivity on MW was found for two sharp absorptions of polystyrene across the MW range from 600 to 2 × 106. It was shown that end group effects for the very‐low‐molecular‐weight polymer fraction may be subtle and should be accounted for when using homopolymer calibration standrads in the study of the dependence of copolymer composition on MW.
Flame‐resistant cotton textiles by a continuous photocuring process
Authors: Harris James A. , Keating Esmond J. , Goynes Wilton R. 
Published: April 2003

AbstractA continuous process for the photoinitiated copolymerization of vinyl phosphonate oligomer (MW 0.5–1.0 kg) and N‐methylolacrylamide from aqueous solutions with cotton printcloth and a sateen fabric was investigated. The free radical reactions, initiated on the cellulose molecules by exposure of the padded cotton fabric to UV radiation gave a flame‐resistant (DOC FF 3‐71 test) textile product. The effects of several variables on the efficiency of oligomer and monomer conversion to polymer add‐on were determined, with maximum efficiencies being 75–85%. Variables were fabric speed through the reactor (0.006–0.039 m/sec), light transmission through Pyrex or quartz windows in the tunnel, four sets of interchangeable tri‐power UV lamps having different spectral distributions and relative intensities, and heat buildup within the reactor. Selected samples of these modified cotton fabrics were evaluated for flame resistance, some textile properties, and elemental phosphorus and nitrogen analysis. Copolymer and phosphorus distribution within and between the cotton fibers were illustrated by transmission electron microscopy and by energy dispersive x‐ray analysis.
Crosslinking of partially neutralized liquid rubbers containing terminal and pendent carboxyl groups with anhydride and bisepoxide
Authors: Matsuda Hideaki 
Published: April 2003

AbstractCrosslinking of partially neutralized liquid rubbers containing terminal and pendent carboxyl groups with anhydride, and bisepoxide was investigated by the carboxyl–anhydride‐epoxide reaction. The partially neturalized liquid rubbers were prepared by the partial neutralization with MgO and CaO from a butadiene (BD)–acrylonitrile (AN) copolymer (Hycar CTBNX 1300X9) with the functionality of 2.4. Bisphenol‐A diglycidyl ether (BADG) was the bisepoxide used, and hexahydropthalic anhydride (HPA) was the anhydride used. The metal carboxylate groups in the system catalyzed the curing reaction. The metal‐containing cured rubbers obtained showed considerably higher tensile strength than the previously reported metal‐containing cured rubbers based on CTBN 1300XB (BD–AN copolymer) with the lower functionality of 1.8. In addition, the cured rubbers generally showed higher water resistance, and lower weight gains in benzene, dioxane, and n‐hexane than the CTBN‐series ones. Thermal behavior and stress relaxation are also discussed.
Photochemical reactions of polyene sequences produced during the degradation of poly(vinyl chloride)
Authors: Owen Eryl D. , Pasha Ishrat 
Published: April 2003

AbstractPhotosensitized reactions of tetrahydrofuran (THF) and dichloromethane (DCM) solutions of polyene sequences introduced into poly(vinyl chloride) molecules by chemical degradation have been investigated. The distribution of polyenes produced following further thermal degradation in DCM were shifted toward longer sequences than were observed for the same reaction in THF. Benzophenone‐sensitized bleaching of the polyene absorption in aerated THF solutions was characterized by induction periods, but the presence of oxygen had little effect on the same reaction in DCM. The bleaching process seems to involve reaction of the polyenes with the tetrahydrofuranyl radical formed by abstraction of the α‐hydrogen from THF by triplet benzophenone. No induction periods were observed for benzoin‐sensitized reactions, but the rate of reaction was faster in DCM than in THF. The differences are discussed in terms of the difference in reactivity of the alkyl and alkoxy radicals.