bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermolysis and hydrogenolysis of polyethylene under steam pressure
Authors: Okui Toshiaki , Ogo Yoshiaki 
Published: April 2003

AbstractThermolysis and hydrogenolysis of polyethylene under steam pressure were carried out by batchwise autoclave in the recovery of liquid petrochemical resources from waste polymers. Thermolysis of polyethylene under steam pressure occurred in the temperature range 400–475°C and reaction pressures up to 213 bar. The presence of steam is advantageous for an increase in liquid products and 450°C is an appropriate temperature for the formation of low molecular aromatic compounds. Hydrogenolysis of polyethylene was studied at 450°C and initial hydrogen pressure range of 10–100 bar under steam pressure. Over 80 wt % of the low‐boiling product was converted to saturated hydrocarbons at 40 bar hydrogen pressure, which corresponds to 1 mole hydrogen to 1 mole monomeric unit of polyethylene. The schemes for the thermolysis and the hydrogenolysis, especially the aromatization, are discussed.
The influence of the relative molecular weight of natural rubber on its thermo‐oxidative stability
Authors: Hrivíková J. , Blažková A. , Lapčík L. 
Published: April 2003

AbstractThe influence of relative molecular weight on rubber thermo‐oxidation in air at 130 ± 1°C has been studied by means of infrared spectroscopy. The carbonyl group formation in single fractions of natural rubber has been measured. It was found that the development of kinetic curves ΔACO = f(t) corresponds for both fractionated and unfractionated extracted samples. Kinetic curves of natural rubber formation are characterized by an induction period τ. Its magnitude is a function of molecular weight up to the value [η] = 0.2 m3/kg, and then stays invariant to changes in [η]. In the range of low values of the internal viscosity up to 0.2 m3/kg, the dependence τCO = f[η] has an exponential character as a consequence of the statistical character of chains breaking down during the degradation. It has been proved that the reciprocal value dependence of the mean viscosity molecular weight of unfractionated acetone‐extracted natural rubber on the length of induction period is linear. The change in double‐bond amount during the oxidation is not reflected in the induction period determined by infrared spectroscopy.
The dimensional changes of partially oriented polyester yarns subjected to dry and wet heat
Authors: Warwicker J. O. , Vevers B. 
Published: April 2003

AbstractThe dimensional changes of partially oriented (PO) polyester yarns subjected to dry and wet heat under different tensions and at different temperatures are described. The mechanical properties of the PO yarns, together with those of the heated yarns, have been measured. A tentative theory of the changes in structure taking place in the yarns is suggested.
Effect of tensile strain rate on the mechanical properties of polystyrene and high‐impact polystryene
Authors: Yokouchi Mitsuru , Uchiyama Haruji , Kobayashi Yasuji 
Published: April 2003

AbstractThe dependency of the mechanical properties (Young's modulus, maximum load, breaking strain, and breaking energy) of polystyrene (PS) and high‐impact polystyrene (HIPS) on the tensile deformation speeds was examined without changing the mode of deformation or the shape of the test specimen. It was found that HIPS has an excellent mechanical balance compared with PS for both low (1.7 × 10−4 to 2.9 × 10−2 m/sec) and high (1.3–16m/sec) speeds. This is due to the following two mechanisms ( which have different time responses) originating from the dispersed rubber particles: (1) at low speeds, the generation of large numbers of microcrazes, and (2) at high speeds, tensile‐orientation hardening of the rubber and cold‐drawing of the PS matrix resulting from the rise in temperature accompanied by the abrupt eleongation of the rubber phases.
Laminating wood adhesives by generation of resorcinol from tannin extracts
Authors: Pizzi A. , Daling G. M. E. 
Published: April 2003

AbstractResorcinol has been generated in situ by high levels of sulfitation of the tannin extract of the black wattle tree (Acacia mearnsii, formely mollissima). Consequently, weather and boil‐proof tannin‐based cold‐setting adhesives for wood, satisfying the requirements of international standards, have been prepared and optimized by halving the amount of resorcinol chemical added to the tannin. Sulfitation afforded also considerable improvement of the “drying out” time characteristics of these adhesives.
Graft copolymerization of poly(vinyl chloride) with styrene. II. Thermal behavior
Authors: Sharma K. K. , Varma I. K. 
Published: April 2003

AbstractThermal behavior of graft copolymers of polyvinyl chloride with polystyrene prepared by using a cationic initiator (AlCl3) was evaluated by measurement of rates of dehydrochlorination in nitrogen atmosphere. With increase in the extent of grafting the rates were found to decrease. Dynamic thermogravimetric analysis revealed an overall improvement in thermal stability of copolymers. Development of polyene sequences in degraded polymer samples was evaluated by measurement of electronic absorption spectra. In comparison to PVC, graft copolymer samples had fewer conjugated double bonds.
Melting and crystallization of nylon 6 containing copper chloride
Authors: Siegmann A. , Baraam Z. 
Published: April 2003

AbstractThe melting and crystallization of nylon 6/copper chloride system has been studied by differential scanning calorimetry. In light of the strong melting temperature depression, above the expected in a polymer–diluent mixture and the strong retardation of the crystallization rate, a high degree of binding, probably even complexing, between the salt and the polymer chain is discussed.
A similarity criterion of the optimal process in melt spinning
Authors: Kwon Y. D. , Butler R. H. , Prevorsek D. C. 
Published: April 2003

AbstractExperimental and simulation studies of optimization of the melt spinning process were carried out for nylon 6 fibers. The experiment and process simulation demonstrated that one criterion that can be applied in scaling up an optimized melt spinning process is to achieve the similar real time history of temperature and deformation rate in the spinway. Some aspects of the experiments and process simulation are discussed, together with the results of real time history analysis for a case of nylon 6 spinning.
Polymerization of ethylene and propylene initiated by milled alumina powder
Authors: Kurokawa Norio , Tabata Masayoshi , Sohma Junkichi 
Published: April 2003

AbstractGeneration of free radicals (mechano‐radicals) by the milling of alumina powder at 77 K was demonstrated by ESR. After milling of alumina in the presence of ethylene (simultaneous milling) at 77 K, polyethylene‐propagating radicals instead of the alumina mechano‐radicals were detected by ESR. Also the contact of ethylene with the milled alumina converted alumina mechano‐radicals into polyethylene propagating radicals at a temperature above the melting point of ethylene. The products extracted by hot toluene from the simultaneous milling were identified by IR to be polyethylene, and their molecular weights were roughly 10,000. The residues after the extraction were bonded with the alumina. Polypropylene was also produced by a similar method of milling of alumina in the presence of propylene. The obtained polyproylene was atactic, and its molecular weight was about 400.
Synthesis and properties of photosensitive rubbers. I. Direct addition reaction of α,β‐unsaturated carboxylic acids to polydienes and polypentenamer
Authors: Azuma Chiaki , Sanui Kohei , Ogata Naoya 
Published: April 2003

AbstractThe addition reaction of α,β‐unsaturated carboxylic acids to polydienes, such as cis‐1,4‐polybutadiene, 1,2‐polybutadiene, and polypentenamer, was investigated in the presence of acid catalysts in order to obtain photosensitive rubbers. The structures of products obtained were identified as cyclized polydiene rubbers having pendent α,β‐unsaturated carboxylate groups. The amount of the incorporated substrates increased up to the maximum of around 20 mole %, and the amount of the residual unsaturated groups in the polymer backbone decreased because of cyclization of the double bond. The products had two glass transition temperatures. These glass transition temperatures were identified as follows: a lower transition, owing to the original polydiene segment where the incorporated carboxylate groups were located; and a higher one, owing to cyclic segment. These two thermal transitions on the polymer backbone indicate that the cyclic structure exists as a block segment in the polymer and the carboxylate group is incorporated at random in a polydiene structure. The synthetic condition needed to obtain a desired amount of the incorporated substrate and the degree of the cyclization of polydienes and polypentenamer were investigated.
Grafting vinyl monomers onto cellulose. I. Graft copolymerization of methyl methacrylate onto cellulose using quinquevalent vanadium ion
Authors: Lenka Subasini , Nayak Padma L. , Mishra Munmaya K. 
Published: April 2003

AbstractGraft copolymerization of methyl methacrylate on cellulosic materials with the use of quinquevalent vanadium as an initiator was studied. Increase of V5+ion concentration up to 0.0025 mole/liter increases graft yield, and with further increase of the initiator the graft yield decreases. The graft yield increases with increase of monomer concentration. The increase of acid concentration is accompanied by decrease of graft yield. A measurable increase in graft yield was observed with increase in temperature from 65 to 75°C. The graft yield is medium and substrate dependent. A suitable kinetic scheme has been pictured and a rate equation has been derived.
Dynamic and steady‐state rheological measurements on polymer melts
Authors: Schulken R. M. , Cox R. H. , Minnick L. A. 
Published: April 2003

AbstractMany attempts to correlate steady‐state and dynamic rheological data have been reported. Thus far, the correlations have not been convincing, particularly for polymer melts that exhibit highly non‐Newtonian behavior. The purpose of this work was to provide a means for obtaining a useful correlation. The Maxwell viscoelastic model was used to correlate data from four different modes of shear—two involving steady‐state deformation and two involving dynamic deformation. As certain defined requirements were met, excellent agreement was obtained for polymer melts that represent a wide range of viscoelastic behavior. One of these requirements was that the polymer molécule should have a certain degree of flexibility.
Physical aging of poly(acrylonitrile‐butadiene‐styrene). I. Dynamic mechanical measurements
Authors: Wyzgoski M. G. 
Published: April 2003

AbstractInjection‐ and compression‐molded poly(acrylonitrile–butadiene–styrene) (ABS) samples were aged at 40 to 90°C in a nitrogen atmosphere. Dynamic mechanical measurements show that aging restricts molecular mobility in the glassy poly(styrene–acrylonitrile) matrix of ABS. The α, or glass transition, of the matrix is affected only by aging at higher temperatures such as 90°C. On the other hand, the β transition is suppressed to some extent by aging at all temperatures from 40 to 90°C parallels the loss of tensile elongation previously reported. These results indicate that the effects of aging on the glassy phase are unique for different aging temperatures. Therefore, a simple time temperature superposition may not exist for the effects of physical aging on ABS.
Physical aging of poly(acrylonitrile‐butadiene‐styrene). II. Differential scanning calorimetry measurements
Authors: Wyzgoski M. G. 
Published: April 2003

AbstractThermal analysis has been employed to study the effects of physical aging on poly(acrylonitrile–butadiene–styrene) (ABS). Physical aging refers to the thermoreversible molecular rearrangements which occur in the glassy poly(styrene–acrylonitrile) phase of ABS. Results demonstrate that the effect of aging on the glassy phasse is dependent on the aging temperature. The extent of physical aging can be measured quantitatively by enthalpy changes in the glassy phase. However, aging is seen to occur even at room temperature and this must be taken into account in making enthalpy change measurements. The physical state of the aged ABS depends upon the specific time and temperature path taken during aging. This implies that a simple time–temperature equivalence does not exist for physical aging. Quantitative correlations between enthalpy changes and mechanical property changes are not observed for properties measured at low speed. However, preliminary data suggest that a correlation does exist for properties measured at high speeds such as impact strength.
Digital comparison of x‐ray diffraction data from cotton textiles
Authors: French Alfred D. , Mitcham Donald , Rowland Stanley P. 
Published: April 2003

AbstractIt is proposed that step‐scanned digital x‐ray diffraction data from closely similar samples be compared only after averaging several scans. The comparison of averaged data for two samples is shown directly by a running difference curve; more subtle differences are indicated by a running sum of difference curve. In order to compensate for inequalities arising from experimental difficulties, scaling of the two data sets may be optionally accomplished by either equating the total intensity sums or performing a least‐squares fitting. Comparison of the two scale factors and consideration of the intercept (background) and resulting standard deviation provide a quantitative estimate of the difference between samples. The proposed techniques are illustrated for hydrocellulose II, cotton treated with acid, flame retardant, and permanent‐press agent, and for the experimental differences of intact cloth versus pressed pellet and different beam‐current settings on the diffractometer.
Selective aminolysis of mixed esters of cellulose
Authors: Månsson Per , Westfelt Lars 
Published: April 2003

AbstractAminolysis of cellulose esters was investigated. Of the amines tested (pyrrolidine, n‐butylamine, sec‐butylamine, 2,2‐dimethylpropylamine, piperidine, cyclohexylamine, morpholine), pyrrolidine was the most reactive. The rate of aminolysis by pyrrolidine was approximately the same in dioxane as in dimethyl sulfoxide (DMSO). Using pyrrolidine in DMSO, the relative order of reactivity of the cellulose esters studied was acetate > butyrate ≫ phenylpropionate. With two mixed esters, cellulose acetate 2‐phenylpropionate and cellulose acetate polystyrene carboxylate, deacetylation could be achieved with high specificity. Pyrrolidine in DMSO may also be used to perform a controlled deacetylation of cellulose triacetate in a homogeneous solution down to a degree of substitution of about 0.05. The aminolysis conditions did not cause any degradation of the cellulose chains.
Polyester–polycarbonate blends. VII. Ring‐containing polyesters
Authors: Cruz C. A. , Barlow J. W. , Paul D. R. 
Published: April 2003

AbstractThermal analysis was used to show that blends of poly(1,4‐cyclohexanedimethylene succinate) (PCDS) with polycarbonate (PC) are completely miscible in the amorphous phase. Blends of PC with poly(ethylene orthophthalate) (PEOP) were found to have a miscibility gap in the midconcentration range and are thus not miscible in all proportions. Similarly, a commercial copolyester formed from ethylene glycol, 1,4‐cyclohexanedimethanol, terephthalic acid, and isophthalic acid is partially miscible with PC. These observations are discussed in terms of the structural features of the three polyesters.
Radiation‐induced polymerization of ethylene in pilot plant. V. Molecular weight distribution of polyethylene
Authors: Yamaguchi Kouichi , Watanabe Hiromasa , Sugo Takanobu , Watanabe Terutaka , Takehisa Masaaki , Machi Sueo 
Published: April 2003

AbstractThe molecular weight distribution of the polyethylene produced by radiation in a large‐scale pilot plant at pressures of 105–395 kg/cm2 and temperatures of 30–80°C was determined by gel permeation chromatography and discussed in connection with the polymerization conditions. The bimodal molecular weight distribution was observed in most of polymers. The number‐average molecular weight at two peaks are 104, and 105, respectively. The fraction of the peak at higher molecular weight increased with pressure and mean residence time, and with decreasing dose rate and temperature. The distribution was unimodal in the early stage of the operation and became bimodal, remaining unchanged in the later stage. The distribution also changed from bimodal to unimodal with rising temperature. These results were consistent with those in static batch experiments and well explained by the polymerization scheme assuming two physical states to be different in polymer mobility.
Apparent viscosity of a fluid–gas mixture
Authors: Lewis David H. , Ryason P. R. 
Published: April 2003

AbstractThe inertia free flow of a one‐dimensional, isothermal fluid–gas mixture in a tube of constant radius is analyzed. The fluid is viscous, non‐Newtonian, and incompressible; the gas is inviscid and compressible. Integration of the equations of continuity, momentum, and state enable the prediction of axial pressure, velocity, density, volumetric flow rate, and shear–stress profiles. Departures from corresponding profiles observed in the flow of non‐Newtonian power‐law fluids are evident. The apparent viscosity of the fluid–gas mixture is computed and compared to that of the fluid alone. A reduction in apparent viscosity is noted. Previously reported experimental evidence of a reduction in viscosity in a non‐Newtonian fluid–gas mixture is recalled and it is claimed that the physical model presented here is capable of explaining the observed reduction in apparent viscosity.
Effect of sorbed water on dielectric and mechanical properties of polyion complex
Authors: Yano Okimichi , Wada Yasaku 
Published: April 2003

AbstractEffect of sorbed water on dielectric and mechanical properties is studied for three kinds of polyion complex (PIC) membranes formed from equal moles of polyanion [poly(sodium 4‐vinylbenze‐sulfonate)] and three polycations of different structural isomerisms [poly(4‐vinylphenethyltriethylammonium bromide), poly(3‐vinylphenethyltriethylammonium bromide), and random copolymer of these monomers]. Sorption isotherms and swelling characteristics indicate that PIC of parapolycation includes more water microphases than PIC of meta‐polycatio. Complex dielectric constants of three PICs with varied water contents are measured at frequencies from 10 Hz to 100 kHz and the relaxation is analyzed in terms of the heterogeneous structure. Stress–elongation relationships of PICs equilibrated with water and aqueous NaBr indicate that yield and break stresses are higher for PIC of meta‐polycation than that of para‐polycation and decrease with increasing NaBr concentration above 0.1M.
Measurement of number‐average molecular weights and second viral coefficients of polyolefins using an improved vapor pressure osmometer
Authors: Mirabella Francis M. 
Published: April 2003

AbstractOperation of an improved design of a vapor pressure osmometer for polyolefins at 140°C is described. Reproducibility of ±10% of the measured number‐average molecular weight (Mn) was obtained with a maximum Mn of about 45,000–50,000. Results are reported for some standard and commercial, linear and branched polyethylenes and for commercial polypropylenes.
Bitumen–silica model composites: The role of the filler
Authors: Fritschy Gabrielle , Papirer Eugène 
Published: April 2003

AbstractThe storage moduli of bitumen–silica model composites obey a simple relationship: E′ = E′0 + Aϕψ, where ϕ is the filler volume ratio and ψ the bitumen–silica interfacial area for a unit volume of composite. This equation is experimentally varified taking various silicas of different surface areas or chemical surface reactivity. The influence of the interface properties on the mechanical glass transition temperature is also examined.
Formation of high‐performance fiber morphologies
Authors: Abhiraman A. S. 
Published: April 2003

AbstractProcesses aimed at forming high‐performance fiber morphologies from rigid, semirigid, and flexible polymers have been analyzed. Routes that rely at least partially on the favorable thermodynamic consequences of conformational rigidity imparted by intramolecular and polymer–solvent interactions are shown to offer much greater promise than those that rely entirely on externally applied deformation.
Graft polymerization of methyl methacrylate onto wool initiated by ferric acetylacetonate/dichloroacetic acid system
Authors: Yoshikuni Masako , Saito Kazuki , Kojima Kuniharu 
Published: April 2003

AbstractThe graft polymerization of methyl methacrylate (MMA) initiated by ferric acetyl acetonate/dichloroacetic acid [Fe(acac)3–Cl2CHCOOH] system onto wool has been investigated in a mixture of water and dioxane. No grafting occurred in organic solvent; water was essential to the grafting. Both the total conversion and the percentage of grafting showed maxima when the mole ratio of Fe(acac)3 and Cl2CHCOOH was ¼. Increasing wool content increased the percentage of grafting, while homopolymer conversion was independent of wool content. The rate of grafting was not proportional to MMA concentration. The grafting mechanism was discussed from these results.
Plastisols of poly(vinyl chloride); particle size distribution, morphology, rheology, and mechanism of aging
Authors: Nakajima N. , Daniels C. A. 
Published: April 2003

AbstractPlastisols of poly(vinyl chloride) (PVC) are suspensions of fine resin particles in plasticizer with about a 50% resin volume fraction. Typically, the gross particle size ranges from about 15 to 0.2 μm and smaller, where the common practice of spray drying these resins dictates that the size ranges include agglomerates as well as the ultimate particles. In this work we have related the particle size distribution to the dynamic mechanical behavior with model plastisols prepared from various particle‐size fractions of a commercial resin. This relationship, together with the microscopic observation of the particle dispersions, provided an interpretation of the plausible mechanisms of the viscoelastic response. The morphological observation of the particle aggregates, the changes of the particle size distribution during the aging, and the above viscoelastic study have established that deagglomeration is the dominant cause of the increase of viscosity during aging.
Flame retardancy of polypropylene and impact polystyrene: Phosphonium bromide/ammonium polyphosphate system
Authors: Granzow A. , Savides C. 
Published: April 2003

AbstractThe individual and the combined effects of the phosphonium salt Cyagard RF‐1 and ammonium polyphosphate on the oxygen index of polypropylene and high‐impact polystyrene have been studied. The synergistic action of the two flame retardant components is evaluated quantitatively, and a correlation between char yield and synergism is discussed. The chars are characterized in terms of their elemental composition.
Stereoregularity of PVC studied by 13C NMR
Authors: Liu Nan‐I , Tong S. N. , Koenig Jack L. 
Published: April 2003

AbstractThe proton decoupled 13C NMR spectra of PVC polymerized at various temperatures were obtained using a 150‐MHz NMR spectrometer. Chemical shift changes induced by a solvent effect were utilized to allow the detection of the six possible tetrads. Eight of ten possible pentads were also observed. The relative areas of tetrads and triads indicate that the polymerization of PVC above −20°C is Bernoullian.