bluuebunny/crossref_metadata_2025 huggingface dataset:
Chemical modification of viscose rayon by dimethyl and methylvinyl diacetoxysilanes
Authors: Bajaj P. , Mandal T. K.
Published: April 2003

Crosslinking of viscose rayon filament with dimethyl and methylvinyl diacetoxysilanes in benzene has been studied. The extent of crosslinking appears to depend on the nature of the reactant, material‐to‐reactant ratio, time, and temperature of the reaction. An increase in the breaking stress, initial modulus, and recovery properties was observed with increase in the crosslink density. Birefringence values as well as orientation index decrease in the treated samples. Thermal behavior of the crosslinked viscose was also studied by TGA and DTA, and it was found that IPDT (integral procedural decomposition temperature) and Dmax (maximum decomposition temperature) values of the crosslinked samples are higher than those of the untreated viscose.
Thermal decomposition behavior of sericin cocoon
Authors: Tsukada Masuhiro
Published: April 2003

The behavior on thermal degradation of the sericin cocoon consisting of a sericin and a few fibroin has been examined by means of evolved gas analysis (EGA), evolved gas detection (EGD), and differential thermal analysis (DTA). The sericin cocoons produced from the silkworm (Nd, Nd‐s/Nd‐s,Nd‐s/+) and sericin stripped from the silk gland in the silkworm show two endothermic peaks at 220°C and 270°C according to differential thermal analysis. From the x‐ray diffraction pattern, dynamic mechanical measurement, and the thermal gravity analysis (TG), the former peak occurs by the scission of the structural state and the change from crystalline to amorphous. Moreover, at 220°C, the weight changes markedly, the yellowness index (L/b) measured by the color difference meter abruptly decreases, and the gas (CO2), evolved from the sericin cocoon, shows increases above 200°C.
Evidence for the reduction of quinones added during thermal processing of polypropylene and the resultant effect on polymer light stability
Authors: Allen N. S. , McKellar J. F. , Protopapas S. A.
Published: April 2003

The thermal and photochemical oxidation of anthraquinone‐ and p‐benzoquinone‐doped polypropylene has been studied by absorption, luminescence, and infrared spectroscopy. Prior to irradiation, fluorescence and phosphorescence measurements showed that some of the anthraquinone and most of the p‐benzoquinone had been converted into their corresponding hydroquinones during processing. The p‐benzoquinone, unlike anthraquinone, also imparted a blue coloration to the polymer before irradiation, which is associated with the formation of a quinhydrone complex (or complexes). These results indicate that the quinones are thermally reduced to their corresponding hydroquinones during processing by a mechanism of hydrogen atom abstraction from the polymer substrate. On photo‐oxidation, whereas anthraquinone acted as a photosensitizer, p‐benzoquinone acted as a photostabilizer.
Foam inhibition in an aqueous sodium dodecylbenzene sulfonate solution by poly(dimethylaminoethyl methacrylate)
Authors: Matsumoto Tsunetaka , Baccay Romeo A. , Okubo Masayoshi , Nakamae Katsuhiko
Published: April 2003

The mechanism of foam inhibition in an aqueous sodium dodecylbenzene sulfonate (DBSNa) solution by temperature‐sensitive, water‐soluble poly(dimethylaminoethyl methacrylate) (PDM) was investigated. The solution's foam collapsing rate, % transmittance, surface tension, pH, temperature, and degree of hydrophobicity of PDM showed that aging a PDM–DBS solution 125 to 280 hr produced a turbid solution and effectively inhibited foaming. Likewise, controlling the pH at 4 ≤ pH ≤ 7 and increasing the hydrophobicity of PDM enhanced the foam‐inhibiting action of the polymer. The reaction between DBSNa and PDM was temperature dependent and the temperature effect was almost reversible. When compared with other available commercial antifoaming agents, PDM was found most effective in suppressing foam formation in aqueous DBSNa solution.
Fiber recovery
Authors: Brody H.
Published: April 2003

The recovery portions of the stress–strain cycles of poly(ethylene terephthalate), poly(tetramethylene terephthalate), nylon 66, poly(vinyl chloride), and rayon were analyzed and shown to be superposable if appropriate horizontal and vertical shifts are made. The recovery curves are postulated to represent the stress–strain behavior of an elastomeric portion of the fiber which controls recovery, and the scaling factors necessary for superposition are interpreted as indicating changes in the “length” and “modulus” of the elastomer. The elastomer modulus correlates very well with the slope of the stress–strain curve, showing that the elastomer governs the fiber stress during extension. Temporary set is assumed to be due to a temporary localized ordering of the elastomer modulus, which disappears when stress is completely removed. This local ordering lowers the elastomer modulus, which leads to yield points in the stress–strain curves. Permanent set is initiated just before the temporary set approaches a constant value and increases at almost the same rate as the rate of extension. It is completely recovered by heating to near the Tg.
Molecular motion in cured epoxy resin filled with mica flakes
Authors: Iisaka K. , Shibayama K.
Published: April 2003

Molecular motion in cured epoxy resin filled with mica flakes was investigated by dynamic mechanical and broad‐line nuclear magnetic resonance measurements. Temperature dependences of dynamic modulus and tanδ were determined at 10 Hz for samples containing various amounts of filler. A primary dispersion temperature, T∞, corresponding to the glass transition, shifts to higher temperature with increasing filler volume fraction Vf. The magnitudes of the slope parameters Hr (representing storage modulus E′ data below Tg) decreased with increasing Vf, but Hg (representing E′ data below Tg) remained nearly constant over the whole loading range studied here. NMR line shapes were observed over the temperature range from room temperature to about 200°C for unfilled and filled samples. Each sample showed a distorted line shape in the transition region where major narrowing occurs. The distorted line shape was decomposed into both broad and narrow components by Gaussian analysis. The temperature range where both components can be obtained becomes broader with increasing filler content. The possibility is set forth that the filler immobilizes the chain segments and causes a different distribution of local mobility around the junction point.
Molecular weight–viscosity relationships for poly(1,4‐butylene terephthalate)
Authors: Borman W. F. H.
Published: April 2003

The correlation between number‐average molecular weight and intrinsic viscosity in 60:40 phenol‐sym‐tetrachloroethane at 30°C for poly(1,4‐butylene terephthalate) was established from endgroup determinations as well as by gel permeation chromatography, eqs. (1) and (10a). The GPC data also yielded relationships between weight‐ and z‐average molecular weight and intrinsic viscosity, eqs. (10b) and (10c). Melt viscosities, corrected for the thermal history of the melt, were measured at shear stresses in the range of 0.02–0.55 MPa. Linear PBT melts were found to become non‐Newtonian at a shear stress of approximately 0.11 MPa, independent of molecular weight within the range studied. Correlations between melt viscosity at low shear stress versus intrinsic viscosity are presented, as well as the dependence of melt viscosity in the non‐Newtonian region on shear stress and low‐stress (Newtonian) melt viscosity.
Copolymerizations initiated by mechano‐radicals on particle surfaces of poly(tetrafluoroethylene)
Authors: Sakaguchi Masato , Sohma Junkichi
Published: April 2003

Mechanical fracture of solid poly(tetrafluoroethylene) (PTFE) produces main‐chain scissions of the polymer, and free radicals, called mechano‐radicals, are trapped on fresh surfaces generated by the fracture. These radical conversions were verified by ESR observation when several monomers—methylmethacrylate, vinylacetate, and ethylene—were brought into contact with these mechano‐radical, and the copolymerizations of PTFE with these monomers were demonstrated. It was found that a new surface property, wettability of water, was added to the solid PTFE by the copolymerization with vinyl acetate, although the bulk nature of PTFE was not changed.
Water‐soluble photocurable elastomer
Authors: Jones G. D. , Hoornstra C. W. , Leonard D. E. , Smith H. B.
Published: April 2003

A low molecular weight copolymer of vinylbenzyl chloride and butadiene was quaternized with N‐dimethylaminoethylmethacrylamide. The resin was coated from water solution to give a photorelief plate which could be developed with water. A photocured protective coating on steel showed good toughness.
γ‐radiation‐induced telomerization of vinyl acetate, styrene, and methyl methacrylate
Authors: Altmann O. , Fehrmann U. , Schnabel W.
Published: April 2003

Vinyl acetate (VAc), styrene (St), and methyl methacrylate (MMA) were irradiated in dilute solution at an absorbed dose rate of 0.5 Mrad/hr in the absence of oxygen at room temperature. In homogeneous systems, telomers are formed with a rate ∝ [M]1 at monomer concentrations [M] > ca. 0.4M. The chain length (D.P..n) increases with increasing [M]. (D.P..n)−1 depends over large ranges of [M] linearly on the ratio [S]/[M] (S = solvent) in accordance with the Mayo equation. These findings were obtained with VAc in methanol and with St in cyclohexane. In heterogeneous systems, telomer is formed at all monomer concentrations. The 100‐eV yield for telomer formation passes a maximum of GT(–M) = 40 (MMA in 2‐propanol) and GT(–M) = 27 (MMA in cyclohexane) at the onset of polymer formation ([M] ∼ 3 vol‐%). With the system St/2‐propanol, GT(–M) ∼ 15 was found being independent of [M]. The molecular weight Mn (telomer) increased from ca. 600 to ca. 1200 by increasing [M] up to 100 vol‐% (MMA/2‐propanol). Mn (telomer) does not depend on [M] in the other two cases (Mn ∼ 500, MMA/cyclohexane; Mn ∼ 700, St/2‐propanol).
Cationic latex interaction with pulp fibers. I. Deposition of styrene‐butadiene latex having quaternized amino groups
Authors: Alince B. , Inoue M. , Robertson A. A.
Published: April 2003

Four experimental latexes of different styrene‐butadiene ratios stabilized with quaternized amino groups were employed in deposition studies on unbeaten kraft pulp fibers. The attraction between the oppositely charged latex and fibers facilitates a ready latex deposition in the pH region between the points of zero charge of the latex and of the fibers. The rate of deposition appears to be controlled by latex diffusion and convection up to the fiber surface. The distribution of latex particles deposited on the fiber surface is related to the butadiene content and the latex stability. Polystyrene latex is the most stable and covers the fibers uniformly as individual particles. With increased butadiene content, the coagulation region of the latex is more extended and the tendency to deposit as aggregates is promoted.
Preparation of soapless latexes by sonification of starch‐based poly(isoprene–co–acrylonitrile) graft reaction mixtures
Authors: Gugliemelli L. A. , Doane W. M. , Russell C. R.
Published: April 2003

Graft copolymerization of isoprene (IP) and acrylonitrile (AN) onto gelatinized starch (S) and cationic starch having quaternary amine functionality through cerium(IV) initiation gave grafted side chains of poly(IP–co–AN). Grafts of various compositions are obtained by controlling the amounts and ratios of monomers added to starch. IP alone does not homograft onto gelatinized starch at 25° or 50°C by cerium(IV) initiation and requires the presence of an “initiator–monomer” such as AN to obtain copolymer side chains. Although cografting of IP and AN onto starch depends on AN to initiate radical chains, the ratio employed of the two monomers is critical for graft polymerization to occur. For example, at a molar ratio of IP to AN of 1 or greater, little polymer was produced; at molar ratios in the range of 0.4 to 0.67, considerable amounts of polymer were produced; and at a molar ratio of 0.13 or less, polymerization of AN was greatly retarded. Concentration of HNO3 in the cerium(IV) reagent and reaction temperature also influence the grafting reaction. Lower HNO3 concentrations favor grafting at 50°C, while higher acid concentrations favor grafting at 25°C. Starch graft reaction mixtures were sonified at 20 kHz to form latexes that air dry to clear pliable films. Poly(IP–co–AN) obtained by acid hydrolysis of the starch portion of the grafts failed to dissolve in either dimethylformamide or benzene, thus indicating presence of crosslinks. S–g–poly(IP–co–AN), having about one third starch and grafted side chains averaging about 2 parts polymerized IP per part of polymerized AN, was masticated on steel rolls at 100°C to a tough pliable film which was subsequently vulcanized to a rubber.
The effects of weathering and atmospheric pollutants on cotton fabric and cotton fabric treated with selected flame retardants. I. Physical, chemical, and flammability properties
Authors: Slaten B. L. , Spivak S. M. , Smith B. F.
Published: April 2003

The effects of weathering and atmospheric pollutants on the physical, chemical, and flammability properties of cotton fabric treated with Pyrovatex 3805 and with THPOH‐NH3 flame retardant finishes and untreated controls were determined. The fabrics were exposed to SO2, NO2, and ozone singly and in combination for 50, 100, and 150 hr in a 2500‐watt xenon arc Weather‐Ometer using gas controls with and without light at a temperature of 35°C and a relative humidity of 90%. Excessive strength losses and large changes in D.P. for the untreated control occurred under all exposure conditions after 150 hr. Changes in the physical and chemical properties of the treated fabrics were moderated by the finishes, with Pyrovatex 3805 providing better protection to the cellulose than THPOH‐NH3. Elemental analysis and oxygen index measurements indicate that the Pyrovatex 3805 finish was severely degraded under these exposure conditions, with a resultant loss in flammability properties of the treated fabric after weathering. The THPOH‐NH3 finish was not appreciably affected by these exposure conditions and the treated fabric retained most of its flammability properties after weathering.
Syntheses of functional condensation polymers. II. A polyamide having epoxy groups and its ring‐opening derivatives
Authors: Shimozato Yasuyuki , Sanui Kohei , Ogata Naoya
Published: April 2003

Polyamides having epoxy groups and their ring‐opening derivatives were prepared and characterized, and some of their properties were investigated. Reaction conditions for the low‐temperature polycondensation of cis‐2,3‐epoxysuccinyl chloride (ESC) with aromatic diamines and the interfacial copolycondensation of ESC and adipyl chloride (AC) with aromatic diamines were established to obtain a high molecular weight polyamide having epoxy groups. In addition, the ring‐opening reactions of the epoxy groups in the polyamides were carried out with various amines in order to obtain polyamides having hydrophilic pendent groups such as amino and hydroxyl. It was found that the polyamides prepared by ring‐opening reaction of the epoxy group with ethylenediamine (EDA) or ethanolamine (EA) had a higher affinity for moisture than those with hexamethylenediamine (HMD) or n‐butylamine (n‐BA), which might be ascribed to the distance of hydrophilic groups from the polyamide chain. Those polyamides having hydrophilic pendent groups decomposed upon heating at less than 200°C.
Uniplanar orientation of poly(p‐phenylene terephthalamide) crystal in thin film and its effect on mechanical properties
Authors: Haraguchi Kazutoshi , Kajiyama Tisato , Takayanagi Motowo
Published: April 2003

The uniplanar orientation of poly(p‐phenylene terephthalamide) (PPTA) crystal was investigated by x‐ray and infrared measurements. Thin PPTA films 3–15 μm thick were prepared by coagulating a sulfuric acid solution of PPTA with various coagulants. Two types of uniplanar orientation were observed, depending on the coagulant used. Thin film coagulated with water exhibits (0k0) uniplanar orientation and film coagulated with other coagulants such as methanol, ethanol, and acetone exhibits (h00) uniplanar orientation. These (h00) and (0k0) uniplanar orientations are formed with crystal modifications I and II, respectively. The (0k0) uniplanar orientation transforms to (h00) upon annealing, accompanying crystal transformation from modification II to modifications I. These uniplanar orientations may result from anisotropic crystal growth due to polymer–coagulant interaction along the hydrogen bond direction. The effect of these uniplanar orientations on the mechanical properties was also examined. The thin film having the (0k0) uniplanar orientation shows ductile fracture, whereas the one having the (h00) uniplanar orientation shows brittle fracture upon tensile deformation. These results are explained on the basis of the direction of the uniplanar orientation of the hydrogen‐bonded sheet.
The effect of grafting on rubber‐phase oxidative etch resistance in high‐impact polystyrene
Authors: Hall R. A. , Jacoby P.
Published: April 2003

A relatively simple, reproducible method for the determination of grafting in high‐impact polystyrene (HIPS) shows that high‐ and low‐graft HIPS exhibit differences in morphology following treatment with an oxidative etching solution. Because this method is quite sensitive to small differences, it yields a more definitive evaluation of grafting in the finished polymer than any other previously used analytical procedure. These differences have been quantified, and the data used to compare relative grafting in polystyrenes reinforced with the same or different rubber types. The method shows an increase in grafting when either the peroxide initiator feed level or 1,2‐vinyl content of the polybutadiene is increased.
Chemical modification of nylon 6 by organoacetoxy‐ and ethoxysilanes
Authors: Bajaj P. , Sharma A. K.
Published: April 2003

Chemical crosslinks were introduced in nylon 6 filament by means of organoacetoxy‐ and ethoxysilanes in benzene under anhydrous conditions. A comparison of the relative reactivities of these silanes toward nylon was made on the basis of the weight add‐on calculated from silicon analysis. Application of acetoxysilanes on preswollen nylon caused an increase in the breaking stress and extensibility. However, a decrease in the initial modulus, birefringence, and moisture regain was observed. An improvement in the thermal stability has also been observed in the crosslinked samples.
Degradation of poly(vinyl chloride) to small molecules
Authors: Schwenk Ulrich , Lömker Franz , König Inge , Streitberger Horst
Published: April 2003

By treatment with alkali in 2‐methoxyethanol, poly(vinyl chloride) is converted to an insoluble network structure. On subsequent oxidation with 65% HNO3, a water‐soluble mixture of acids is obtained. Per 1000 carbon atoms of the original polymer chain, approximately 4 moles succinic acid, 2 moles glutaric acid, and 1 mole adipic acid are found. In spite of the fact that the occurrence of succinic acid is in the same order as tail‐to‐tail polymerization in PVC, it must be assumed that unexpected aggregation of more than two CH2 groups is due to rearrangement during the alkali treatment or the oxidation procedure.
Flocculation of dispersions by preferential adsorption of solvents from polymer solution
Authors: Sato Tatsuo
Published: April 2003

An attempt was made to account for the adverse effect of the preferential adsorption of solvents onto particles from polymer solution (negative adsorption of polymer) on the stability of a dispersion in terms of osmotic attraction. The change in the energy of osmotic attraction on collision of solvated particles in a solution of macromolecules was calculated as a function of an osmotic pressure of the media, the thickness of the solvation layers, and the size of solute molecules, based on the assumption that the adsorption is irreversible and the adsorbed layers are impenetrable. The result showed that the energy of osmotic attraction is of the same order of magnitude as that of the electrostatic repulsion, indicating that the flocculation caused by the negative adsorption of polymers is mainly due to the osmotic attraction.
The determination of particle size distribution by hydrodynamic chromatography. An analysis of dispersion and methods for improved signal resolution
Authors: Silebi C. A. , McHugh A. J.
Published: April 2003

Various methods are described and compared for the determination of particle size distributions (PSD) in the submicron range by a technique known as hydrodynamic chromatography (HDC). Data are presented for a series of monodisperse latexes to establish the validity of the Mie theory of light scattering in describing the detector optical density signal. Analyses for the PSD involve corrections to the experimental HDC chromatograms for the effects of dispersion and are broadly classified as integral and numerical methods. Comparisons of calculations are made to chromatograms for polydisperse latexes as well as synthetic, discontinuous distributions and show the critical role of the optical density–particle size relationship in determining resolution and calculation stability. An integral method involving a non‐Gaussian form for the dispersion function and a polynomial expansion for the chromatogram and an iterative numerical method involving modifications of a previously published technique are shown to give the best results for the PSD. The discussion includes an analysis of the possibility of improved signal resolution using turbidity in the absorption wavelength region and refractive index measurements. The conclusion is reached that increased resolution with turbidity is preferable to refractive index measurement since lower particle concentrations can be used.
Diffusivity and solubility of organic vapors in modified polyethylene films. I. Technique and analysis of results
Authors: Aboul‐Nasr Osman T. , Huang Robert Y. M.
Published: April 2003

A new method of analyzing unsteady‐state sorption data was developed to determine the diffusivity and solubility of vapors in polymer films. The equilibrium weight increase yields the solubility directly. Analysis of the unsteady‐state data gives the diffusion coefficient and its concentration dependence. A complete method for the analysis of either absorption or desorption results is presented for any type of concentration dependence of the diffusion coefficient. In this paper the method is applied to the Fujita free volume theory. The apparatus and the experimental procedures are discussed in detail.
Emulsion polymerization kinetics and its reactor design. II. The MWD behavior in isothermal batch operation
Authors: Lin Chen Chong , Chiu Wen Yen
Published: April 2003

The emulsion polymerization of styrene in an isothermal batch operation can be divided into three stages, and the corresponding kinetic rate equations are obtained from the experimental conversion‐reaction time curve. The course of polymerization between the beginning of the reaction and any subsequent time is successfully computed for the reaction rate, the MWD, and the average degree of polymerization using the intergrals of these rate equations, which could readily explain the behavior of the emulsion polymerization. A comparison is made between the theoretical results and the experimental data. Both the theoretical treatment and the experimental data predict that the MWD for a typical emulsion polymerization is characterized by the rapid decrease in Mw/Mw ratio at the entrance of the zero‐order stage and a gradual increase in the first‐order stage regardless of an autoacceleration effect. An autoacceleration effect in the first‐order stage is, however, evidence for a typical emulsion polymerization.
Energy balances and uniaxial failure of solid propellants
Authors: Lepie A. H. , Adicoff A.
Published: April 2003

A simple test procedure was used to determine the total damage in a propellant that accumulates during a tensile test from 0% strain to failure. Damage energies of two propellants were measured at various temperatures and straining rates, and Williams‐Landel‐Ferry shift procedures were applied to the results. The reduced master curves for the total damage energy at failure are used to compare the failure behavior of the two propellants.
A quantitative treatment of particle size distributions in emulsion polymerization
Authors: Sundberg Donald C.
Published: April 2003

A quantitative analysis is presented for predicting the particle size distributions obtained in emulsion polymerization. The results obtained are compared with experimental data in terms of the particle‐size‐distribution curves as well as the statistical parameters of the distributions. Comparisons are made for changes in initiator level, surfactant level, water:monomer ratio, and temperature. The manner in which these variables change the distributions and the reasons for these changes are identified. The distribution of radicals among particles of different sizes is seen to be significant. Large particles are expected to contain a greater number of radicals per particle than the smaller ones in the same latex. The effects of such a radical distribution upon the properties of the latex are discussed.
Production of levoglucosan and glucose from pyrolysis of cellulosic materials
Authors: Shafizadeh Fred , Furneaux Richard H. , Cochran Todd G. , Scholl Jackson P. , Sakai Yoshio
Published: April 2003

Vacuum pyrolysis of cellulose within the temperature range of 300–500°C provides a tar fraction containing mainly levoglucosan and glucose condensation products. It was found that pyrolysis proceeds at a much faster rate at the higher temperatures without detrimental effect on the yields. At 400°C the reaction was essentially complete within 3 min yielding a tar that contained 39% levoglucosan and, upon mild acid hydrolysis, gave 49% D‐glucose. The yields could be further improved by washing or treatment of cellulosic substrates with acids. Cotton hydrocellulose provided up to 58% levoglucosan or 77% D‐glucose. This is the highest yield determined by unequivocal methods. Commonly available cellulosic materials such as wood and newsprint give very poor yields of levoglucosan. However, the yields could be improved substantially by acid washing or prehydrolysis to the extent that pyrolysis of these substrates may become an attractive industrial process. The data in this report provide the technical basis for such a process and resolve the existing controversies on the reported yields.
Kinetics and mechanism of the alkali‐catalyzed p‐cresol–formaldehyde reaction
Authors: Malhotra H. C. , Kumar Vinod
Published: April 2003

The kinetics of the reaction of p‐cresol with formaldehyde in relation to the functionality of p‐cresol using NaOH as catalyst has been studied at temperatures of (65 ± 0.05)°C, (70 ± 0.05)°C, (75 ± 0.05)°C, and (80 ± 0.05)°C. The pH maintained was 7.0, 8.0, 9.0, 9.4, and 10.0. The reaction follows a second‐order rate law. The rate was found to increase with increase in pH. The stepwise rate constants (k1 and k2) for the formation of monomethylol‐p‐cresol and dimethylol‐p‐cresol, respectively, were calculated from the overall rate constant k. The values of Arrhenius parameters and the entropy of activation for the overall as well as the stepwise reactions were calculated. The experimental and calculated values of k at pH 10.0 and temperatures 65, 70, 75, and 80°C were found to agree well within experimental errors. A mechanism conforming to the energies and entropies of activation of the reaction is suggested.
“Dry latex.” A new method for the preparation of rubber‐filler powders
Authors: Caspary R. , Heske J.
Published: April 2003

A new method of preparing rubber powders, especially masterbatch powders, is described. It consists of the dispersion of polymer latices in highly hydrophobic fine particle‐size powders such as special silicas and carbon black, followed by drying. During the whole procedure the powders never lose their pourable state. Several powder properties, e.g., particle size distribution, pourability, bulk density, and angle of repose, are dealt with for NR and SBR powders. These powders require a high shear processing stage to disperse the black and rubber chemicals into the rubber matrix. For direct extruder feeding, a highly efficient extruder mixing screw is necessary. It is shown that the powders can be sufficiently protected against aging by use of special antioxidants. The procedure is characterized by an outstanding simplicity in respect to engineering and equipment. The future outcome of the method will depend on the balance between that simplicity and the energy demand which can be tolerated.
Vulcanization of butyl rubber by p‐quinone dioxime dibenzoate
Authors: Gan L. M. , Chew C. H.
Published: April 2003

The maximum crosslink density for the dioxime‐butyl vulcanizate was obtained at equimolar quantity of the dioxime and red lead. The formation of each quinoid crosslink required about 1.25 molecule of p‐quinone dioxime dibenzoate. The vulcanizates consisted mainly of the anil‐type crosslink. It was estimated that about 20% of the combined dinitro compounds was wasted in the form of the pendent groups. The vulcanization mechanisms are also discussed.
Preparation and characterization of poly(methyl methacrylate)–lead silicate composites
Authors: Rabie A. M. , Moustafa A. B. , Badran A. S.
Published: April 2003

Poly(methyl methacrylate)–lead silicate composites were prepared with different amounts of crystalline or amorphous PbO–SiO2 binary composition (70 mole % PbO). The polymerization reaction was carried out in aqueous medium and in methanol–water mixture at 40°C using sodium bisulfite as initiator. The presence of lead silicate was found to increase the molecular weight of the poly(methyl methacrylate). The prepared composites were characterized by studying their shielding properties to γ radiation, mechanical hardness, dielectric constant, and thermal stability. It was found that lead silicate increases the absorbing power of the composites to γ radiation. This behavior was found to be dependent on the amount and the type of lead silicate (amorphous or crystalline). Gamma irradiation of the composites was found to cause chemical degradation of the poly(methyl methacrylate) leading to a decrease in mechanical hardness. Molecular weights of the poly(methyl methacrylate) for some of the composites were determined before and after irradiation viscosimetrically. Dielectric constants for some of the composites were determined at two different temperatures. The thermal stability of the composites was studied by means of an automatic thermogravimetric analyzer.
Recoverable compliance behavior of high‐density polyethylenes
Authors: Plazek Donald J. , Raghupathi N. , Kratz Robert F. , Miller William R.
Published: April 2003

Eight samples of high‐density polyethylene with weight‐average molecular weights ranging from 5.5 × 104 to 17.3 × 104 have been studied. In addition to GPC molecular weight characterization, the recoverable compliance, the shear viscosity, and the extrudate swell were determined at temperatures between 138 and 200°C. The range of the maximum creep stresses ranged from 60 to 1840 dynes/cm2. The creep recovery response was in the linear or near‐linear range. The results are interpreted in the light of the anomalous results of Mendelson and Finger.
Ethylene solubility and diffusion in low‐density polyethylene and ethylene copolymers
Authors: Beret S. , Hager S. L.
Published: April 2003

Evolution rate measurements were conducted to determine the solubility and the diffusion constants of ethylene in three semicrystalline polymers: low‐density polyethylene (LDPE), ethylene‐ethyl acrylate (EEA), and ethylene–vinyl acetate (EVA) copolymers. The apparatus for such measurements utilizes a flame ionization detector interfaced to a computer for continuous monitoring of the ethylene evolution from the polymer pellets. Solubilities are obtained by calculating the total ethylene evolved over a 12–48‐hr period. Analysis of the evolution rate data in terms of the nonsteady‐state diffusion equation for spheres yields the diffusivity. The ethylene solubility and diffusion constants in EVA and EEA are very similar to those in LDPE. This is due to compensating effects of decreased crystallinity and increased cohesive energy density with the incorporation of bulky polar groups into the polymer chain.
Thermogravimetric and mass‐spectrometric study of the thermal decomposition of PBCT resins
Authors: Thomas T. John , Krishnamurthy V. N. , Nandi U. S.
Published: April 2003

The thermal decomposition of three commercial samples of carboxy‐terminated polybutadiene (PBCT) resins was studied by thermogravimetric analysis (TGA) at heating rates varying from 2° to 100°C/min. Kinetic parameters of the decomposition process at different heating rates were evaluated by means of the Fuoss method.1 The decomposition process and the activation energy values are found to be dependent on heating rate. Mass‐spectrometric analysis of the decomposition products shows that the pyrolysis products of PBCT resins are mainly low molecular weight hydrocarbons: ethylene, acetylene, butadiene, propadiene, vinylcyclohexene, etc. The rates of evolution of these hydrocarbon products vary with the carboxy content of the PBCT resin. Based on this, a carbonium ion mechanism has been suggested for the thermal decomposition. The data generated from this work are of importance for a consideration of the mechanism of combustion of composite solid propellants based on PBCT binders.
Graft polymerization of acrylamide and 2‐acrylamido‐2‐methylpropanesulfonic acid onto starch
Authors: Fanta George F. , Burr Robert C. , Doane William M.
Published: April 2003

Mixtures of acrylamide and 2‐acrylamido‐2‐methylpropanesulfonic acid (AASO3H) were graft polymerized onto starch by cobalt‐60 irradiation, and the water absorbency and water solubility of the resulting products were determined. The conversion of monomers to polymer was nearly quantitative when pregelatinized wheat starch and a water solution of the two monomers were simultaneously irradiated (simultaneous irradiation conditions). Products with high water absorbency were obtained with equal weights of starch and total monomers when acrylamide:AASO3H ratios ranged from 9:1 to 1:3. Water solubility of these polymers was over 50%. Neither of the two monomers gave absorbent polymers when graft polymerized individually onto starch. Although highly absorbent products were also obtained at a total monomer:starch ratio of 2:5, ratios of 1:5 and lower gave products with poor absorbency. Neutralization of AASO3H with sodium hydroxide before graft polymerization drastically reduced both the water solubility and absorbency of the final products. A reaction with granular starch was also carried out under simultaneous irradiation with a total monomer:starch ratio of 2:5 and with equal weights of the two monomers. Conversion of monomers to polymer was once again nearly quantitative. To obtain good water absorbency from this granular product, it was necessary to first neutralize the AASO3H portion with alkali, then disperse the polymer in hot water, and finally dry the resulting water dispersion. Graft copolymers with good water absorbency were also obtained by adding preirradiated starch to a water solution of acrylamide and AASO3H, although only partial conversions of monomers to polymer were realized. Selected products from the various graft polymerizations were fractionated by extraction with either water or a 1% solution of sodium chloride. The synthetic polymer content of the resulting fractions and the percentage of AASO3H in the synthetic portion of each polymer were determined. The Mn of some of the synthetic polymers was also determined after removal of carbohydrate by enzymatic hydrolysis.
Structure and properties of o‐carboxymaleanilic polyester resins
Authors: Messiha N. N. , Nosseir M. H. , El‐Hamouly S. H.
Published: April 2003

Polyester resins were prepared by the reaction of o‐carboxymaleanilic acid with ethylene trimethylene, propylene, hexamethylene, diethylene, or 1,4‐butenediol. All the polyester resins obtained have been characterized and were found to cure with styrene, except the polyester from diethylene glycol. The properties of the cured products in the form of films were determined. Infrared. UV, and NMR spectroscopy were used for both qualitative and quantitative analyses of the polyester resins and their hydrolyzate products, after curing with styrene.
The kinetics of hydrolytic polymerization of ε‐caprolactam. II. Determination of the kinetic and thermodynamic constants by least‐squares curve fitting
Authors: Tai Kazuo , Teranishi Hiroichi , Arai Yoshihiro , Tagawa Takashi
Published: April 2003

The kinetic and thermodynamic constants of the hydrolytic polymerization of ∂‐caprolactam were determined by least‐squares curve fitting. The calculations were carried out using observed kinetic data such as concentration of ∂‐caprolactam ([CL]), endgroup ([EG]), and ∂‐aminocaproic acid ([ACA]) and time derivatives of each concentration (rates) ∂[CL]/∂t, ∂[EG]/∂t, and ∂[ACA]/∂t. The sets of the converged constants are obtained for the initial water concentrations of 0.42, 0.82, and 1.18 mole/kg. An averaged set of the constants applicable for this range of the initial composition was also evaluated. The compatibility between observed and calculated concentration and rate curves was improved by the use of the newly developed sets of the constants. The mechanism of the polycondensation reaction is also discussed, based on the rate and kinetic constants obtained by this work.
Effect of temperature on the electrical conductivity of poly(vinyl chloride)–copper composites
Authors: Bhattacharya Swapan K. , Basu S. , De Sadhan K.
Published: April 2003

Effect of temperature on the electrical conductivity of PVC‐copper composites has been studied. The temperature coefficient of dc resistivity of composites with fillers containing negligible oxide content in the range of 77–303 K is positive, indicating metallic‐type conduction. The temperature coefficient of dc resistivity of composites with fillers containing intermediate level of oxide at higher temperatures is negative, indicating a semiconducting behavior. Plots of log conductivity versus log frequency for composites in the insulating region show the hopping‐type conduction.
Radiation‐induced polymerization of ethylene in pilot plant. IV. Kinetic analysis
Authors: Watanabe Hiromasa , Machi Sueo , Kurihara Hirondo , Wada Takeshi , Yamaguchi Kouichi , Watanabe Terutaka , Takehisa Masaaki
Published: April 2003

The kinetics of the radiation‐induced polymerization of ethylene in a flow system using tert‐butyl alcohol aqueous solution as a medium were studied. The polymerization was carried out in a large‐scale pilot plant with a 50‐liter central source‐type reactor at various mean residence times and does rates under constant pressure of 300 kg/cm2, temperature of 30°C, and ethylene molar fraction of ca. 0.4. The reaction mixture in the reactor was back‐mixed flow from the residual polymer concentration in the reactor. The results of the polymerization were analyzed by kinetic treatment based on a reaction mechanism with both first‐and second‐order terminations for the propagating radical. The apparent rate constants, except for that of second‐order termination (kt2), were consistent with those determined by small‐scale batch experiments. The kt2 is 20 to 40 times larger than that in the batch experiments. The kt2 increases with decrease in mean residence time and with agitation, probably because of mobility of the propagating radical.
The molecular factors affecting the solubility parameter
Authors: Peiffer Dennis G.
Published: April 2003

A study of the solubility parameter δ2 was pursed in order to obtain further information on the prominent molecular factors affecting its value. The details of the expressions derived for the components of δ2 depends on the considerable usage of both classical statistical thermodynamics and the well‐know equations for intermolecular forces. The results confirm that relatively simple expressions for the components of δ2 are found. The disperson component of the solubility parameter, δ2d, is a function of the molecular polarizability, fractional polarity, molar volume, and van der Waals volume. The polar component of the solubility parameter, δ2p, is a function of the dipole moment, temperature, molar volume, and van der Waals volume; δ2d is found to increase linearily with molecular size, while δ2p is found to decrease with molecular size (except at low molecular volumes). As will be shown, the expressions derived here have considerable utility in elucidating results obtained by other researchers.
Dyeing of chemically modified cellulose. VII. Dyeability of cellulose bearing aromatic amino, nitro, and acrylamidomethyl groups
Authors: Hebeish A. , Waly A. , Moursi A. Z. , Mohdy F. A. Abdel
Published: April 2003

The effect of introducing aromatic amino, nitro, and acrylamidomethyl groups in the cellulose molecules on the dyeing properties of two direct dyes (Chlorantine Fast Red 6BLL and Solophenyl Orange T4RL) as well as two reactive dyes, (Procion Brilliant Red M5B and Procion Brilliant Orange MG) was investigated. The extent and rate of dyeing for cellulose bearing aromatic amino groups were lower than those of nonmodified cellulose irrespective of the dye used. In addition, the extent of dyeing decreased as the amount of aromatic amino groups increased. The opposite held true for cellulose bearing acrylamidomethyl groups, particularly with direct dyes where increasing these groups caused a substantial enhancement in the dye uptake. On the other hand, subjecting cellulose to nitration reaction prior to dyeing diminished significantly its dyeability with the dyes.
The properties of some poly(arylene ether sulfones)
Authors: Ahmed I. K. , Walker N. , Parsons I. W. , Haward R. N.
Published: April 2003

Some 2,4′‐substituted poly(arylene ether sulfones) have been prepared and their properties compared with those of the conventional 4,4′ homopolymer. The introduction of the comonomer leads to a small increase in yield stress and to a greater tendency to brittle fracture, which can be demonstrated from fracture surface micrographs.
Permeability of oxygen through polymers. II. The effect of humidity and film thickness on the permeation and diffusion coefficients
Authors: Petrak K. , Pitts E.
Published: April 2003

The values of the permeability coefficient P (cm2/sec) and the diffusion coefficient D (cm2/sec), of oxygen in some water‐soluble polymers at various values of relative humidity were determined. The amount of oxygen initially present in the polymer membranes was calculated. The effect of sample preparation and the film thickness on the transport parameters was investigated. The results confirm the possible effect of thickness on the rate of transport of oxygen in water‐soluble polymers.
Molecular weight characterization of polybutadiene rubber with high molecular weight and broad molecular weight distribution
Authors: Ambler M. R.
Published: April 2003

Following the molecular weight characterization of two polybutadiene samples, it was found that Mw from gel permeation chromatography with universal calibration and light scattering were in agreement, but Mn by gel permeation chromatography was less than Mn from membrane osmometry. A more detailed analysis revealed that the high molecular weight and broad molecular weight distribution of the two samples forced two corrections to the membrane osmometry results for (a) diffusional layer effects caused by high solution viscosities, and (b) solute permeability of the membrane. In the latter effect, the high viscosities of the solutions prevented actual diffusion through the membrane, but “reflection” of these species as defined by the Staverman coefficient prevented an accurate Mn determination. After making these corrections, it was found that Mn from membrane osmometry using a very tight membrane was in very good agreement with Mn from gel permeation chromatography. A method is demonstrated for obtaining Mn from a combination of membrane osmometry and gel permeation chromatography, where membrane osmometry data from membranes of different porosities (after corrections for diffusional layers and membrane reflection) are used to verify the accuracy of the gel permeation chromatography data as representing the true molecular weight distribution, allowing the gel permeation chromatography data to be used to calculate Mn.
ESR study of the effect of ferric chloride on the photodegradation of model compound for polypropylene
Authors: Negishi Akio , Ogiwara Yoshitaka
Published: April 2003

In our previous article on the photodegradation of polypropyle (PP), the effect of ferric chloride (FeCl3) accelerating the formation of peroxy radical and depressing the formation of alkyl radical were reported. In the present article, the influence of FeCl3 on model compounds of PP was examined using electron spin resonance (ESR) spectrometry. The following compounds were employed as models of PP, including its irregular structures: 2‐methylpentane (2‐MP), 2,4‐dimethylpentane (2,4‐DMP), 2‐methyl‐4‐pentanone (2‐M4P), 2,6‐dimethyl‐4‐heptanone (2,6‐DM4H), 2‐methyl‐1‐pentene (2‐M1P), and tert‐butylhydroperoxide (t‐BuO2H). FeCl3 accelerated the formation of alkyl radicals for 2‐MP and 2,4‐DMP, alkyl and acyl radicals for 2‐M4P and 2,6‐DM4H, and alkyl radicals for 2‐M1P. As no definite effect of FeCl3 was observed for n‐pentane and 2‐octanone, FeCl3 was assumed to attack saturated hydrocarbons, ketones at a tertiary carbon‐hydrogen bond, and hydrocabons at an allylic hydroge, leading to easier photodegradations. FeCl3 was also effective for the photodegradation of t‐BuO2H using λ >300 nm, so that FeCl3 is believed to contribute also to the photodegradation of PP under the same irradation conditions. The catalytic effect of FeCl3 in photodegradation seems to origirate in a redox reaction.
Influence of hydrofuramide on network structure and kinetics of thiuram vulcanization
Authors: Banerjee B. , Chakravarty S. N. , Biswas A. B.
Published: April 2003

The influence of hydrofuramide (a reaction product of furfural and ammonia) on the network structure and overall kinetics of thiuram vulcanization of natural rubber is reported. The nature of the network structure of the thiuram vulcanizates in the presence and absence of hydrofuramide was determined using triphenyl phosphine (Ph3P) as a chemical probe. The presence of hydrofuramide produces structural complexity of the vulcanizate. The overall kinetics of thiuram vulcanization follows a first‐order‐rate law in the presence as well as in the absence of hydrofuramide. The rate constant increases while the energy of activation decreases in the presence of hydrofuramide.
Formation of polyelectrolyte complex and its adsorption properties
Authors: Kurokawa Yōichi , Shirakawa Namio , Terada Manabu , Yui Norio
Published: April 2003

Polyeletrolyte complex formations between two oppositely charged polyions[ionene, poly(vinylbenzyl trimethylammonium chloride), poly(diallyl dimethylammonium chloride), polyaminesulfone, potassium poly(vinyl sulfate), sodium poly(stylene sulfonate), poly(acrylic acid)] have been investigated by conductance and trubidity measurements. It was found that the complex formation of these polyelectrolytes formed in stoichiometry. Adsorption isotherms of water, methanol, acetone, and benzene were determined for the resulting complexes at 25°C with a gravimetric adsorption apparatus. The differences in adsorption can be exclusively ascribed to differences in ion site and hydrophobic circumstances around the ion site, since each complex has a low specific surface area (<1 m2/g). Amount of adsorption increased in the order of water > methanol > acetone > benzene. This order corresponds to that of the polarity of adsorbate.