bluuebunny/crossref_metadata_2025 huggingface dataset:
Relation between dynamic mechanical properties and dye diffusion behavior in acrylic fibers from polymer blends
Authors: Bryant Y. G. , Murayama T.
Published: April 2003

The extension of the relation between the dynamic viscoelastic parameters (“E” and tan δ) and diffusion coefficient (D) to modified acrylic blend fibers indicates that the dependence of dye diffusion on polymer chain mobility is a general phenomenon not limited to a single component system. The relationship of D to mechanical properties permits one to “tailor” fibers with good mechanical properties while maintaining adequate dye‐diffusion behavior.
Diels–Alder adducts as epoxy resin hardeners
Authors: Matynia Tadeusz
Published: April 2003

The influence of hydroxyl modifiers on the properties of Diels–Alder adducts–terpene hydrocarbons with maleic anhydride—was studied. The mechanical, thermal, and dielectric properties of the composition of Epidian 5 epoxy resin hardened with an adduct modified by ethylene glycol, propylene glycol, dipropylene glycol, glycerin, or hexanetriol are described.
Phthalic anhydride‐based cation exchange resin from N‐vinylcarbazole
Authors: Biswas Mukul , Packirisamy S.
Published: April 2003

A condensation product based on phthalic anhydride and N‐vinylcarbazole has been prepared and processed into a sulfonic acid cation exchange resin. The resin produced has been characterized by measuring its total and salt splitting capacities and by studying its thermal characteristics, rate of exchange, and behavior to pH metric titration.
Strain effects in the mass flux of methanol in poly(methyl methacrylate)
Authors: Ware Robert A. , Cohen Claude
Published: April 2003

Diffusion of organic solvents into glassy polymers often results in a phase transformation of the hard, solid polymer into a swollen, rubbery material. During the sorption, internal stresses exist in the swollen and glassy parts of the polymer and are thought to contribute significantly to the “anomalous” diffusion observed in many penetrant–polymer systems. In this investigation, isothermal sorption data for the methanol–poly(methyl methacrylate) system have been obtained on plates ranging in thickness from 1/32 to ¼ in. The results show features characteristic of both a strain‐dependent diffusion coefficient and of a stress gradient contribution to the mass flux. An attempt to reproduce these results by combining a strain‐dependent diffusion coefficient model with a stress‐induced contribution to the flux is presented.
Functional monomers and polymers. LXX. On the adsorption of iodine onto chitosan
Authors: Shigeno Y. , Kondo K. , Takemoto K.
Published: April 2003

The ability of adsorbing iodine in different organic solutions by chitosan was studied by sorption isotherm measurements. The ability was found to be larger in polar solvents than in nonpolar solvents. The form of the chitosan samples, such as film, powder, and flake, had no influence on the adsorption behavior. On the other hand, chitin had only small adsorbing ability of iodine. It is concluded that the adsorption of iodine is caused by charge—transfer complexes between aminogroups of chitosan and iodine molecules, but their structure differs from that of inclusion compounds as seen in amylose–iodine complexes. The adsorption was also studied on chitosan films with different degrees of acetylation.
Thermolysis and hydrogenolysis of polyethylene under steam pressure
Authors: Okui Toshiaki , Ogo Yoshiaki
Published: April 2003

Thermolysis 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

The 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

The 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

The 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

Resorcinol 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

Thermal 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

The 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

Experimental 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

Generation 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

The 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

Graft 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

Many 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

Injection‐ 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

Thermal 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

It 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

Aminolysis 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

Thermal 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

The 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

The 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

Effect 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

Operation 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

The 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

Processes 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

The 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

Plastisols 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

The 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

The 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.
Effect of relative humidity on the mechanical properties of poly(1,4‐butylene terephthalate)
Authors: Gardner R. J. , Martin J. R.
Published: April 2003

Three grades of poly(1,4‐butylene terephthalate) (PBT) were aged up to three years at 100, 75, 50, and 11% relative humidity and temperatures of 66–93°C. The decrease in mechanical properties, caused by hydrolysis, occurs rapidly at the higher temperatures and relative humidities and progressively slows as the temperature and/or humidity are decreased. Equations for making life‐cycle predictions at any combination of temperature and humidity were derived from Arrhenius plots. If a 50% loss in tensile strength constitutes failure, then the PBT examined should be expected to last only three to four years at 50°C and 100% relative humidity. Reducing the humidity level to 50% extends the useful life at this temperature to 10–20 years. Predictions based on the tensile strength half‐life should not be used where toughness or impact properties are important because PBT embrittles long before the tensile strength half‐life is reached.
Reinforcement of siloxane elastomers by silica. Chemical interactions between an oligomer of poly(dimethylsiloxane) and a fumed silica
Authors: Berrod G. , Vidal A. , Papirer E. , Donnet J. B.
Published: April 2003

The study of the interactions between an organosiloxane and a fumed silica was undertaken in order to improve our knowledge of the reinforcement of silicon rubbers by silica. IR spectroscopy, gravimetry, and chromatography techniques were used to characterize the chemical interactions taking place above 150°C between octamethylcyclotetrasiloxane and a fumed silica which yield silicas modified by grafted siloxanes. Reaction mechanisms were proposed for the interpretation of the grafting processes. They were checked by the study of the reaction of water with octamethylcyclotetrasiloxane. The results obtained suggest that the reactions proceed through an attack of the siloxane by the surface free silanol groups of silica, causing an opening of the siloxane cycle and the grafting of the subsequent material on the surface of the filler. It was shown that the siloxane‐modified silicas exhibit a high thermal stability.
Rubber‐modified epoxies. I. Transitions and morphology
Authors: Manzione L. T. , Gillham J. K. , McPherson C. A.
Published: April 2003

A variety of different morphologies, and therefore mechanical properties, can be obtained from a single rubber‐modified epoxy formulation. The volume fraction, domain size, and the number of particles of phase‐separated rubber are determined by the competing effects of incompatibility, rate of nucleation and domain growth, and the quenching of morphological development by gelation. These factors can be varied by the butadience/acrylonitrile ratio of the reactive rubber, the temperature of cure, and the gelation time. These ideas have been exploited to control the development of morphology of these amorphous systems. Phase separation was investigated by electron microscopy, viscometry, and dynamic mechanical analysis.
Infrared study of the effect of heat on wool
Authors: Moharram M. A. , Abdel‐Rehim T. Z. , Rabie S. M.
Published: April 2003

The infrared spectra of wool heated in vacuum and in air to different temperatures ranging from 120 to 250°C were investigated. It was found that certain absorption bands disappear when wool is heated in vacuum to 180°C and in air to 120°C for 2 hr. Also, the results showed that the intensities of the C=O stretching band at 1660 cm−1, N–H stretching band at 3325 cm−1 and the C–H stretching band at 2940 cm−1 decrease when wool is heated in vacuum to 180°C and in air to 120°C. The spectra of the samples heated in vacuum to 250°C and in air to 225°C exhibited strong absorption bands belonging to the carboxyl and sulfonate groups.
Poly(methyl methacrylate)–cellulose nitrate copolymers. II. Physical and mechanical properties
Authors: Badran B. M. , Sherif Sayed , El‐Sheltawi Sh. T. , Abu‐Sedira A. A.
Published: April 2003

Poly(methyl methacrylate)–cellulose nitrate copolymers were prepared by bulk polymerization using benzoyl peroxide as initiator. Cellulose nitrates of two different nitrogen contents (11.4 and 12.2%) were used. The prepared copolymers were γ‐irradiated for specified periods of up to 11.83 Mrad. Their physical and mechanical properties were measured before and after irradiation. The title copolymers showed lower modulus, tensile strength, and elongation at break than poly(methyl methacrylate) itself, but they showed better hardness and abrasion. Irradiation to up to 6.57 Mrad improved the modulus of the copolymers. Hardness and abrasion were improved by increasing cellulose nitrate content. The prepared copolymers that contained cellulose nitrate of 11.4% nitrogen showed secondary transition points. The increase of cellulose nitrate concentration shifted both first and second transition points to relatively higher values.
Graft polymerization of methyl methacrylate onto chemically modified wools using LiBr–K2S2O8 redox system as initiator
Authors: Niezette J. , Geurts R. , Erilli R.
Published: April 2003

Graft polymerizations of methyl methacrylate onto natural, reduced, S‐carboxymethylated, S‐aminoethylated, sulfated, acetylated, and oxidized wools were performed at 30°C using a LiBr–K2S2O8 redox system as initiator. The extent of grafting was found to be dependent on the thiol and amino contents of wool fibers; carboxylic, sulfated groups, and oxidation intermediates had no significative influence on graft yields. The polymethacrylic chains obtained after hydrolysis of the natural part of the copolymer and analyzed by infrared and NMR spectroscopies were characterized by an atactic structure quite comparable to that found for a corresponding homopolymer. There was no stereoregulating effect on methyl methacrylate polymerization due to the crystalline components of the wool structure. A quantitative determination of the number of amino acid residues linked to the end of polymethacrylic chains after hydrolysis indicated that chain termination occurs both by disproportionation and recombination of macroradicals for natural, sulfated, S‐carboxymethylated, and S‐aminoethylated wools; for reduced and oxidized wools, only a recombination by disproportionation was observed in accordance with the open structure of these wool fibers. The chain lengths of the isolated poly(methyl methacrylates) were also found to be consistent with the participation of thiol and amino groups in grafting. It seems, however, that amino groups do not themselves act as initiating sites.
Corrosion of polymer–concrete composites in hydrochloric acid at elevated temperature
Authors: Yeo R. S. , Zeldin A. N. , Kukacka L. E.
Published: April 2003

A series of polymer–concrete (PC) materials were evaluated in 30% hydrochloric acid at 90°C. It was shown that a polymer aggregated with quartz sand is a potential candidate for use in coating or construction materials for hydrogen–chlorine energy storage systems. The results have shown that the corrosion rate of PC in this solution is a diffusion‐;controlled process. The major weight loss can be attributed to the presence of cement in the PC samples. The influence of the sand/cement ratio, and the crosslinking agent content on the corrosion of PC samples is also discussed.
Photochemistry of polymeric systems. III. Photocrosslinking of polymers and copolymers including cyanocinnamylydene–pyridinium groups
Authors: Roucoux Colette , Loucheux Claude , Lablache‐;Combier Alain
Published: April 2003

Photocrosslinkable polymers were obtained by reacting esters of cinnamic acid or cyanocinnamylideneacetic acid onto pyridine units of a homopolymer or onto a suitable copolymer. These photosensitive polymers were characterized by conventional analysis and spectrometry. The photocrosslinking was studied on thin films measuring the threshold of insolubilization together with UV and IR spectrometry.
Photochemistry of polymeric systems. IV. Photocrosslinking of copolymers including pyridinium dicyanomethylide groups
Authors: Cottart Jean‐;Jacques , Loucheux Claude , Lablache‐;Combier Alain
Published: April 2003

Photocrosslinkable polymers were obtained by reacting tetracyanoethylene oxide with pyridine units of suitable copolymer. Copolymers of styrene and 4‐;vinylpyridine dicyanomethylide were synthetized and studied. The methods used for characterization of photocrosslinked films were a “photoresist test” or the measurement of the insolubilization ratio. The reaction is favored by triplet‐;state sensitizers such as Michler's ketone. The photosensitivity of the copolymers was determined as a function of the wavelength of the radiation used.
Studies on thermal degradation of synthetic polymers. XV. Estimation of the product yield on the basis of intensity function for thermal gasification of isotactic and atactic polypropylenes
Authors: Sawaguchi Takashi , Suzuki Kazumasa , Kuroki Takeshi , Ikemura Takashi
Published: April 2003

The kinetic equation for the pyrolysis gasification reaction of isotactic and atactic polypropylenes has been established. The difference in tacticity of the samples does not much affect the kinetic parameters. The exponent a of the intensity function IF = Tδa (K·seca), concerning the severity of decomposition conditions, has been approximated as 0.039 (isotactic) and 0.040 (atactic), respectively from the kinetic parameters in this experiment. The calculated values of the product yield from Arrhenius equations, k = 2.0 × 1010 exp(−40.9 × 103/RIF) (isotactic) and k = 1.2 × 1010 exp(–41.4 × 103/RIF) (atactic), for the IF standard agree with the experimental values.
Radiation‐induced oxidative degradation of isotactic polypropylene
Authors: Hegazy El‐Sayed A. , Seguchi Tadao , Arakawa Kazuo , Machi Sueo
Published: April 2003

Gas evolution, oxygen consumption, and change of mechanical properties were studied for the γ‐ray irradiation of isotactic polypropylene from 60Co under various conditions, such as vacuum, air, and oxygen at room temperature. For irradiation under vacuum, G(H2) = 2.9 and G (CH4) = 0.09; the G values for other gases were very small. In the presence of oxygen, G(H2) was the same, and the G values for other hydrocarbons were two times those under vacuum. The G values of oxidative products and oxygen consumption were G(CO2) = 2.5, G(CO) = 1.1, and G(O2) = 50 at oxygen pressure of 500 torr and were dependent on oxygen pressure. With irradiation under vacuum at 2–3 Mrad, mechanical properties scarcely changes immediately after irradiation but degrade gradually with storage time in air at room temperature.
Application of refractive index measurements to polymer analysis
Authors: Samuels Robert Joel
Published: April 2003

The availability of a simple experimental technique for determining the three principal refractive indices of an anisotropic film (here defined as the trirefringence technique) makes possible a wide range of optical criteria for evaluating property and processing variables. The present study considers different applications of the refractive index information in order to show the versatility and practical utility of the technique. For example, a normalization procedure is developed which determines equivalent optical anisotropic states of films. This allows films produced by different multiaxial fabrication processes to be compared. Similarly, procedures are described for characterizing the crystallinity, the angular optical distribution in the plane of the film, and other interesting applications of the refractive index information.
Measuring diffusion coefficients by hygroelasticity
Authors: Marom G. , Broutman L. J.
Published: April 2003

A new method for obtaining diffusion coefficients of polymers and composites by measuring relative length changes is proposed. The method is based on interrelating diffusivity and hygroelasticity, and it is applicable to materials whose dynamic and equilibrium stage coefficients of hygroelasticity are equal.
Polymer solutions from latexes
Authors: Wong Chi Shing , Rodriguez Ferdinand
Published: April 2003

In order to characterize a polymer by its reduced viscosity, it is necessary to put it into solution. For polymer made by emulsion polymerization, this usually involves coagulating the latex, washing and drying the coagulum, and then dissolving the residue in an organic solvent. The method fails when the polymer crosslinks on drying, as is the case with some adhesive resins. The method proposed here uses mixtures of N‐methylpyrrolidone (NMP) and tetrahydrofuran (THF) to put the polymer directly into solution without removing the water. The technique is applicable to many polymers and copolymers of ethyl acrylate and vinyl acetate.
Effect of oven aging on polypropylene
Authors: Wyzgoski M. G.
Published: April 2003

Injection‐molded tensile bars of unstabilized polypropylene were oven aged at 90°C. After an induction period, tensile elongation decreased catastrophically. During the induction period no evidence of oxidation was observed by infrared reflectance; however, a definite surface etching was noted by electron microscopy. Differential scanning calorimetry measurements indicated that, for samples aged beyond the induction time, oxidative degradation caused a decrease in the melting temperature of polypropylene. Toluene immersion was used to remove selectively material from the surface of tensile bars aged for various times. Using this technique, changes in melting behavior were observed for partially aged polypropylene even prior to the catastrophic decrease in tensile elongation. Similarly, oxidation products and a reduction in molecular weight were detected for the dissolved surface layer during the apparent induction time. Results indicate that molecular weight measurement is the most sensitive indicator of oxidative degradation during the induction period.
Hydrolytic degradation of polyglycolic acid: Tensile strength and crystallinity study
Authors: Chu C. C.
Published: April 2003

The hydrolytic degradation of polyglycolic acid (PGA) was studied by examining the changes of tensile strength and the level of crystallinity of the suture material. It was found that the breaking stress decreased from 6.369 × 10−1at 0 day to 3.97 × 10−3Newton/Tex at 49 days. The sigmodial shape of the stress–strain curves gradually disappeared with increase in the duration ofin vitradegradation. The endpoint titration method used to assess the degree of degradation beyond the period of measurable tensile strength showed that the percent of PGA degraded were 42, 56, and 70% at 49, 60, and 90 days, respectively. The level of crystallinity of PGA at various durations of degradation exhibited an initial increase in the degree of crystallinity from 40% at 0 day to an upper limit of 52% at 21 days, then gradual decrease to 23% at 90 days. This observation is essentially parallel to hydrolysis of cellulose and polyethylene terephthalate. The concept of microfibrillar structure of fibers provides the basis for the proposed degradation mechanism of PGAin vitro.It is believed that degradation proceeds through two main stages which are different in rate of degradation.
The effect of heat setting on the structure and mechanical properties of poly(ethylene terephthalate) fiber. II. The elastic modulus and its dependence on structure
Authors: Gupta V. B. , Kumar Satish
Published: April 2003

The effects of temperature, time of heat setting, and rate of cooling on the elastic modulus of free‐and taut‐annealed poly(ethylene terephthalate) (PET) fibers were determined at different time scales using Instron, Rheovibron, and pulse propagation meter. The correlation of the elastic modulus with structure is critically examined in terms of the widely used simple one‐phase and two‐phase models for fiber modulus. It is concluded that these simple models are not universally applicable.
Crack‐tip plastic zones in glassy polymers under small‐scale yielding
Authors: Gdoutos E. E.
Published: April 2003

Two pressure‐modified von Mises yield criteria were used for the determination of the plastic zones developed around cracks subjected to opening‐mode loading conditions in glassy polymers. These criteria take into account the particular behavior of glassy polymers expressed by the dependence of their yield locus on the hydrostatic stress component and the difference in their tensile and compressive yield stresses. It was found that both criteria predict larger plastic zones than those obtained by the von Mises criterion which increase as the ratio of the compressive to tensile yield stress also increases. Furthermore, it was established that the differences in the predictions of plastic zones between the two criteria and the von Mises criterion increase with the Poisson's ratio of the material of the cracked plate.
Characterization of cured polystyrylpyridine by model compounds
Authors: Hsu Ming‐Ta S. , Rosenberg Mark L. , Parker John A. , Heimbuch Alvin H.
Published: April 2003

The crosslinking or curing reaction of polystyrylpyridine (PSP) has been studied by means of thermal reactions of its model compounds. Compounds 2,6‐distyrylpyridine, 4‐stilbazole (4‐styrylpyridine), and deuterated 4‐stilbazole were pyrolyzed at 200–325°C both in air and under vacuum in a sealed tube. The major pyrolysis products were diarylethane and stilbene, and were characterized by gas chromatography‐mass spectrometry. Major dimeric products were naphthalene or quinoline derivatives. Mechanisms for the pyrolysis are suggested, and a crosslinked structure for cured PSP is proposed based on the thermal reaction products of model compounds.
Compatibility in a blend of poly(2,3‐dichloro‐1‐propyl acrylate) and poly(glycidyl methacrylate–co–ethyl acrylate)
Authors: Davis D. D. , Taylor G. N. , Kwei T. K.
Published: April 2003

The compatibility of mixtures of poly(2,3‐dichloro‐1‐propyl acrylate) and poly(glycidyl methacrylate–co–ethyl acrylate) has been investigated by measurement of the following properties: density, light transmission, glass transition temperature, vapor absorption, and NMR relaxation times. To varying degrees, all results provided evidence supporting the contention that these mixtures are compatible.
Preparation of amphoteric latex by modification of styrene–acrylamide copolymer latex
Authors: Kawaguchi Haruma , Hoshino Hirotomo , Ohtsuka Yasuji
Published: April 2003

Styrene–acrylamide copolymer latex prepared from the polymerization in an emulsifier‐free aqueous medium was treated with hypochlorite and sodium hydroxide. The resulting latex indicated amphoteric property due to amino and carboxyl groups formed by the Hofmann reaction and competitive hydrolysis of amide groups, respectively. Amphoteric latices with the same particle size but different charge density (1.0–3.0 ionic groups/100 Å2) and different isoelectric points (6.4–9.2) have been prepared by changing the reaction conditions.
Surface characterization of polyester fibers
Authors: Gillberg Gunilla , Kemp David
Published: April 2003

Fibers made from poly(ethylene terephthalate) (PET) are characterized by a hydrophobic surface with low reactivity. Modifications of the PET surface to render a higher degree of hydrophilicity and reactivity are therefore common. The modification often involves a surface layer of only a few nanometers thickness. The relatively low fraction of the modified surface layer and the fact that it is generally an organic modification on a thin curved organic substrate presents difficulties in surface analyses. Surface characterization is, however, of high importance in the evaluation of the degree and durability of a given surface modification. The paper will discuss the possibilities and the limits of using wettability studies according to the Wilhelmy method to evaluate the degree of surface modification and its permanence. Comparison between internal and external reflection Fourier‐transform infrared spectroscopy will be made. The use of electron spectroscopy for chemical analysis, secondary ion mass spectrometry, laser microprobe mass analysis, and microprobe molecular optics laser examiner will be illustrated. Data will be presented from studies of model yarns and films coated with D‐417 dip.
Grafting of methyl methacrylate on EPR and EPDR: Impact properties of polyvinyl chloride grafted polymer blends
Authors: Beati E. , Pegoraro M. , Briano M.
Published: April 2003

EPDM rubber can be brought into water suspension after swelling in n‐heptane containing proper emulsifiers and in shear stress; particles reach dimensions as low as 150 Å. Methyl methacrylate in emulsion can be grafted easily with Bz2O2 on the rubber. Grafting yields depend particularly on the monomer/rubber ratio. The grafted polymer can be recovered by precipitating the emulsion with acetone, which eliminates the homopolymer. The grafting mechanism is discussed in terms of different initiators (AIBN and Bz2O2) and unsaturated (EPDM) and saturated rubber (EPR); AIBN and PMMA radicals were inactive in abstracting hydrogen atoms from rubber chains. Mechanical properties of the blends with PVC of the raw graft product are discussed on the basis of the grafted polymer composition and synthesis conditions. Very high impact strength can be reached at 15% rubber content in the blend for a grafted polymer obtained from a monomer/rubber ratio equal to 0.75.