bluuebunny/crossref_metadata_2025 huggingface dataset:
Spectroscopic elucidation of chemical structure of plasma‐polymerized pyridine
Authors: Hozumi K. , Kitamura K. , Hashimoto H. , Hamaoka T. , Fujisawa H. , Ishizawa T.
Published: April 2003

Chemical structure of the plasma‐polymerized pyridine film produced on a glass reactor wall by means of the plasma technique in which the pyridine vapor was electronically excited by high‐frequency power under a reduced pressure was elucidated. The polymer was highly hydrophilic and was soluble to some of the polar organic solvents so that nitrogen‐containing polar functional groups were predicted to participate in the chemical structure of the polymer molecules. 1H‐NMR, 13C‐NMR, and IR spectroscopies, high‐resolution mass spectral data, and number‐average molecular weight determination with some aid of microelemental analysis revealed the presence of various functional groups such as imine, nitrile, amine, pyridine ring, its N‐oxide, and even amide. The oxygen atoms involved in the last two groups were supposedly introduced by contact with ambient air after the plasma process. The hydrophilic nature of the polymer which was essential for preparing reverse osmosis membrane was therefore due to the overall hydration effect of these polar functional groups.
Acid distribution in carboxylated vinyl‐acrylic latexes
Authors: Gajria C. , Vijayendran B. R.
Published: April 2003

Distribution of acid groups in carboxylated vinyl‐acrylic latexes has been determined by a combination of aqueous conductometric and nonaqueous potentiometric titrations. Titrations analysis of vinyl acrylic latexes, in comparison to earlier reported studies with carboxylated polystyrene and all acrylic latexes, is complicated by the presence of acetic acid which originates from the hydrolysis of polyvinyl acetate. Most of the copolymerized carboxylic acid is located at the latex particle surface with some of it being buried within the particle. No serum phase polymeric carboxylic acid is detected. Polymerization conditions and the choice of the carboxylic monomer affect acid distribution. Effect of acid distribution on some latex properties is also discussed.
Diluent diffusion in polymer‐diluent systems near Tg: Migration of phthalic esters from PVC to water
Authors: Zieminski Kenneth F. , Peppas Nikolaos A.
Published: April 2003

A new mathematical model is presented for the description of certain types of diluent diffusion (migration) through diluent–polymer systems. The model describes anomalous diluent transport into a container of finite volume, and it incorporates mass transfer limitations at the polymer/extractant interface. The extractant is assumed to diffuse slowly or negligibly into the polymer. The model is applied to experimental data obtained with two plasticizers, di(2‐ethyl‐n‐hexyl) phthalate and benzyl butyl phthalate, migrating from poly(viny1 chloride) to water.
Influence of hydrati ability of monomer on immobilization of microbial cells by radiation polymerization
Authors: Kumakura Minoru , Kaetsu Isao
Published: April 2003

The influence of the hydrratin ability of monomer on the immobilization of microbial cells by radiation polymerization was studied using various acrylate and diacrylate monomers. The heats of mixing of the monomers in water were determined, and the hydratin abilities of monomer and polymer were evaluated by heat of mising and water content. The shape of the immobilized cell composites varied with the hydratin ability of monomer. The enzymatic activity of the immobilized cell composites varied with the number of ethyleneglycol or methylene units in the monomers. In the immobilization using acrylate monomers, the increase of the hydration ability of the monomer introduced a spongelike composite to the formation of the immobilized cells, and, in diacrylate monomers, the increase of the hydration ability of the monomer introduced a flakelike composite to the formation of the immobilized cells, by which enzymatic activity increased.
Optimal temperature profiles for nylon 6 polymerization in plug‐flow reactors
Authors: Ramagopal A. , Kumar Anil , Gupta Santosh K.
Published: April 2003

Optimal temperature profiles for nylon 6 polymerization in plug‐flow reactors have been obtained under different conditions using a reasonable objective function which gives more flexibility to a designer than those studied earlier. Computations suggest that the temperatures at the feed end of the reactor must be maintained at the highest permissible level (determined by the boiling point of the ϵ‐caprolactam) so as to force the degree of polymerization rapidly to the desired value. Thereafter, the temperatures should be reduced in order to minimize the undesirable cyclic dimer concentration, and, finally, near the exit of the reactor, the temperature must once again be increased in order to attain higher monomer conversion. The effect of a systematic change of values of the various design variables, one by one, is studied. The profile obtained differs substantially from those obtained by earlier workers because of the difference in the objective function as well as in the kinetic mechanism associated with the formation of the cyclic oligomer. Attempts are also made to obtain a global optimal scheme to produce a polymer of a desired degree of polymerization.
DSC study of the polyurethane formation from poly(ethylene adipate) and toluene diisocyanate
Authors: Ferrillo R. G. , Arendt V. D. , Granzow A. H.
Published: April 2003

The reaction of poly(ethylen adipate) (PEA) and toluene diisocyanate (TDI) is studied by means of isothermal DSC. The reaction has the stoichiometry of PEA/TDI = 0.5 and a reaction enthalpy of ΔH = −65.0 kJ/mol hydroxyl group. The kinetic order is unity over a wide range of temperature and composition of the reaction mixture. The temperature dependence of the first‐order rate constant yields an apparent activation energy of 61.1 kJ/mol. The kinetic data are accommodated by the following rate law:

A mechanism involving a mobile preequilibrium to accommodate the experimental results is proposed.
Flame retardance in polyester fabric radiolytically grafted with bromostyrene
Authors: Mey‐Marom A. , Rajbenbach L. A. , Levy M.
Published: April 2003

Ionizing radiation was employed to graft bromostyrene (BSy) onto poly(ethylene terephthalate) (PET) fabric. The fire‐retardant effect of the polymerized monomer on PET fabric was evaluated both by LOI tests and by DTA and TGA methods under conditions of controlled total combustion. The yields of HBr and BSy evolved during pyrolysis in the presence and absence of oxygen were determined. A linear correlation was found between ΔOI values and yields of HBr, and the implications of this finding are discussed. It is suggested on the strength of DTA and TGA results under total combustion conditions that the fire‐retardant effect of poly(bromostyrene) manifests itself mainly by a physical‐mode mechanism through a significant reduction in the release of flammable gases.
Influence of the stiffness of testing machines on the adherence of elastomers
Authors: Barquins Michel
Published: April 2003

It is shown that the introduction of the fracture mechanics concepts, such as the strain energy release rate G, to solve the problem of the adherence of elastomers, the edge of contact being seen as a crack propagating in mode I in the interface, allows one to predict the dependence of the adherence force with the stiffness of testing machines. Moreover, it is shown the general equation of the kinetics of adherence proposed in 1978 by Maugis and Barquins, G–w = wϕ(atv), where w is Dupré's work of adhesion and ϕ a dissipation function characteristic of the material only depending on temperature and crack speed, is confirmed whatever the stiffness of the testing machine and the instantaneous deformation imposed on the system. Experiments realized with a hemispherical glass lens in contact on a polyurethane surface verify theoretical predictions with an accuracy better than 1%.
Tear strength theory of semicrystalline polymers
Authors: Rohn C. L.
Published: April 2003

A theroretical model describing how the tear strenght of semicrystalline polymers depends upon the interaction of the crystalline and amorphous phases is presented. It is based upon the “freevolume“ theory and a “Hooke's law ‐lattice energy” treatment. The strength TM is hypothesized to be partitioned between the crystalline Qc and amorphous Qa phases. Therefore TM∝︁ Qc. Qa, TM = To.Qc.Qa, where Qc = NKTE/bY2 and e−v/vf =G/Goτ. Proof of this theory is obtained by measuring the oxygen transmission rates of 11 polyethylene film samples varying in tear strenght. Good agreement exists between TM (experimental) and TM (theroetical) for 9 of the polyethylene samples. The other 2 Samples differ from the theory by factor of 2. One explantion of this departure is the τ varies from unity.
Rheology‐processing‐property relationships in tubular blown film extrusion. I. High‐pressure low‐density polyethylene
Authors: Han Chang Dae , Kwack Tae Hoon
Published: April 2003

Three different grades of high‐pressure low‐density polyethylene resin were used to establish relationships between tubular film blowability and the molecular parameters, namely, the molecular weight distribution (MWD) and the degree of long‐chain branching (LCB), and also between the processing conditions and the mechanical properties of the tubular blown films produced. For the study, both the shearing and elongational flow properties of the resins were determined. During the tubular film blowing experiment we measured the freeze‐line position, the tubular bubble diameter, the takeup speed, the axial tension, the pressure inside the tubular bubble, and the mass flow rate of the resin. The thickness of the tubular blown films was measured from the samples collected. In order to determine the tubular film blowability, we measured the maximum takeup speed at which the tubular blown bubble broke, for various blowup ratios. The measurements described above permitted us to calculate the tensile stresses at the freeze line, in both the machine and transverse directions, and they were found to be correlatable to the processing conditions employed. It has been found that the tubular film blowability is increased as the resin's MWD becomes narrower and the degree of LCB is less. It has been found further that a resin having lower elongational viscosity tends to give a greater draw‐down ratio, indicating a better tubular film blowability. Finally, the tensile properties of the tubular blown films were found correlatable to the processing variables, namely, blowup and takeup ratios.
Rheological properties of branched low‐density polyethylene
Authors: Han Chang Dae , Kim Yong Joo , Chuang Hsiao‐Ken , Kwack Tae Hoon
Published: April 2003

The shear flow properties of six commercially available long‐chain branching low‐density polyethylene resins were determined, using a cone‐and‐plate rheometer at low shear rates and a capillary rheometer at high shear rates. Also determined were the elongational viscosities of the resins, using an apparatus developed by Ide and White. Interpretation of the rheological measurements is given with the aid of the molecular parameters, namely, molecular weight and molecular weight distribution.
The mechanics of tubular fiber: Theoretical analysis
Authors: Gupta Dinesh K.
Published: April 2003

A mathematical model of a tubular fiber is analyzed to predict its rigidity and some of its physical properties which are essential in textiles. The change in the properties of a tubular fiber with increase in the size of hollow core is considered and compared with the cylindrical fiber of the same outside diameter, the same denier, and the same rigidity as that of the tubular fiber. The equations are developed in dimensionless quantities to make them invariant to the units of fiber dimensions. The analysis revealed that having a hollow core of 4/10th the size of the outside diameter, in a solid fiber, could reduce the fiber weight by 16% without making any significant change in the rigidity of the fiber.
Studies of tetrazoles as rubber chemicals. I. Preparation and characterization of reactive antioxidants based on tetrazoles
Authors: Otomo S. , Sako T. , Yamamoto Y. , Yamashita S.
Published: April 2003

The novel reactive antioxidants based on tetrazoles that are stable at room temperature and convertible into the highly reactive nitrileimines by pyrolysis were prepared and the reactivity for carbon–carbon double bonds was evaluated. Antioxidants, i.e., 2‐substituted phenyl‐5‐(3′,5′‐di‐tert‐butyl‐4′‐hydroxyphenyl)tetrazoles (PHPT) were prepared with the reaction of p‐toluenesulfonylhydrazone of 3,5‐di‐tert‐butyl‐4‐hydroxybenzaldehyde and substituted phenyl diazonium chloride in a mixed solvent of pyridine, ethanol, and water at −10°C to −20°C in 31‐61% yields. To evaluate the reactivities of PHPT for carbon–carbon double bonds, m‐chloro‐substituted PHPT was pyrolyzed in an excess of styrene at 160–170°C for 0.5 h to give the 1‐(3′‐chlorophenyl)‐3‐(3″,5″‐di‐tert‐butyl‐4″‐hydroxyphenyl)‐5‐phenyl‐2‐pyridazoline in a 44.1% yield by 1,3‐dipolar addition reaction of the nitrileimine formed from the m‐chloro‐substituted PHPT. The thermogravimetric analysis of a mixture of proton isomer of PHPT and liquid polybutadiene showed that PHPT attached to liquid polybutadiene with an accompanying evolution of nitrogen.
Equilibrium acid concentrations in hydrolyzed polyesters and polyester–polyurethane elastomers
Authors: Brown Daniel W. , Lowry Robert E. , Smith Leslie E.
Published: April 2003

Equilibrium acid concentrations, [Ae], were determined in butylene adipate and caprolactone polyesters, of low molecular weight, and in thermoplastic polyurethane elastomers based on these polyesters. Values of [Ae] of the polyesters at 85°C were 0.7, 1.3, and 3‐4 × 10−3 mol/g at relative humidities (RH) of 25%, 50%, and 93%, respectively. [Ae] of the thermoplastic elastomers at 85°C were about 3 and 7 × 10−4 mol/g at 10% and 25% RH, respectively. Values of [Ae] were not very dependent on temperature at constant RH. Equilibrated thermoplastic elastomers had low molecular weights and poor physical properties. Consequently, equilibration does not set a practical limit on hydrolytic degradation, even at low RH. Equations were developed that described the variation in acid content with time. Rate constants for hydrolysis and esterification increased as RH decreased. Reesterification in the elastomers in the absence of water is too slow to be a useful method of decreasing hydrolytic damage.
Ionomeric blends. IV. Miscibility of urethane elastomers with styrene–styrene sulfonic acid copolymer
Authors: Rutkowska M. , Eisenberg A.
Published: April 2003

Blends were prepared from two kinds of urethane elastomers, containing 1,4‐butanediol or 3,3′‐dichloro‐4,4′‐diamino‐diphenyl‐methane as chain extenders, with lightly sulfonated polystyrenes. Dynamic mechanical studies show that strong interactions occur between the sulfonic acid and the urethane or urea moieties on the polyurethane chains. These strong interactions are clearly seen in the composition dependence of the loss tangent peaks (due to the glass transitions) for both the high temperature and the low temperature glass transitions of the blends. They are further confirmed by model studies.
The preparation of multiaxially oriented polyethylene morphologies with high mechanical properties in planar direactions
Authors: Zachariades Anagnostis E.
Published: April 2003

The development of multiaxially oriented films of low molecular weight (Mw ≈ 59,000) high density polyethylene with high mechanical properties in planer directions has been pursued by inducing fibrillar crystallization under curvilinear flow conditions in a contained geometry using an extrudomolding process and by simulating similar crystallization conditions in an optical plate–plate rheometer. The films, like the uniaxially drawn morphologies of the same low molecular weight high density polyethylene by solid‐state extrusion, had a high modulus (12–20 GPa) and strength (0.25 GPa) along the residual flow lines but they exhibited also a modulus enhancement (5 GPa) in the transverse direction as a result of the orientation gradient of the molecular chains in the thickness directions.
Kinetic and thermogravimetric analysis of the thermal oxidative degradation of flame‐retardant polyesters
Authors: Cooney J. D. , Day M. , Wiles D. M.
Published: April 2003

Untreated and flame‐retarded poly(ethylene terephthalate) fabrics have been subjected to thermogravimetric analysis in air at several heating rates between 0.1°C/min and 100°C/min. The data have been analyzed using a variety of methods to obtain kinetic parameters for the sequential stages in the thermal degradation process. The data obtained reveal that the phosphorous‐only flame retardants do not significantly effect the degradation kinetics. The two bromine‐containing flame retardants, however, are capable of modifying the degradation kinetics, with the Dacron 900F material being responsible for a beneficial condensed‐phase effect while the TRIS‐treated sample is responsible for reduced activation energies and more rapid weight loss.
Grafting of poly‐β‐alanine onto carbon black: The hydrogen transfer polymerization of acrylamide catalyzed by n‐butyllithium in the presence of carbon black
Authors: Tsubokawa Norio , Nagano Yukihiro , Sone Yasuo
Published: April 2003

The hydrogen transfer polymerization of acrylamide (AAm) catalyzed by n‐butyllithium in the presence of carbon black was carried out at 80–100°C and the grafting of poly‐β‐alanine (nylon 3) was investigated. It was suggested that the growing polymer anion was captured by the quinonic oxygen group on the surface of carbon black. Furthermore, the growing polymer anion reacted with the phenolic hydroxyl group on the surface to give ungrafted polymer and the lithium phenolate (O−Li+) group (chain transfer to phenolic hydroxyl group). The O−Li+ group formed was considered to be capable of initiating the hydrogen transfer polymerization of AAm. Accordingly, during the hydrogen transfer polymerization in the presence of carbon black, poly‐β‐alanine was effectively grafted by the termination of growing polymer anion and the propagation of the polymer from the O−Li+ group on the surface. The grafting ratio was determined to be 60–80%. The carbon black obtained from the polymerization gave a stable colloidal dispersion in water, N,N‐dimethylformamide, and formic acid. Furthermore, it was found that the ratio of hydrogen transfer polymerization to normal vinyl polymerization (T ratio) increased with an increase in polymerization temperature.
Dynamic mechanical properties of polypropylene composites filled with ultrafine particles
Authors: Sumita Masao , Tsukihi Hidetoshi , Miyasaka Keizo , Ishikawa Kinzo
Published: April 2003

The dynamic moduli of isotactic polypropylene (PP) filled with ultrafine SiO2 and micron sized glass particles are measured in the temperature range 30–130°C at frequency 10 Hz. The storage moduli of PP composites, E′c, increase with filler content and decreasing filler size in the whole range of temperature. The loss moduli of PP composites, E″c, increase with filler content and decreasing filler size above 40°C. The intensity of the broad despersion which appears at ca. 60°C increases with filler content and decreasing filler size. By assuming that the energy is not dissipated in the effective volume, namely, filler volume plus that of immobilized interfacial region, the effective volume fraction is evaluated from the relative loss modulus, E″cE″0 at 60°C. The effective volume fraction increases with filler content and decreasing filler size. The effect of addition of ultrafine particles on the broad dispersion at ca. 60°C resembles the effect of increasing crystallinity of pure PP. It is concluded that the broad dispersion which appeared at ca. 60°C seemed to be assigned to the grain boundary of PP composities or crystalline boundary of pure PP.
Compatibility of polystyrene and poly(methyl methacrylate) of various molecular weights in toluene
Authors: Lau Wayne W. Y. , Burns Charles M. , Huang Robert Y. M.
Published: April 2003

Gel permeation chromatography has been successfully used to determine the compositions of the conjugate phases in the system of polystyrene and poly(methyl methacrylate) with toluene as solvent. Application of this method to equilibrated samples yields tie lines, binodal curves, and plait points. Polymer–polymer compatibility and the polymer–polymer interaction parameters at the plait points in this system were found to be strongly dependent on the molecular weights of the polymers.
Modified cellulose acetate membranes for desalination
Authors: Ghatge N. D. , Sabne M. B. , Gujar K. B. , Mahajan S. S.
Published: April 2003

Residual hydroxyl groups of commercially available cellulose acetate (39.9% acetyl) have been reacted partially with phenyl isocyanate. The characteristics of these modified polymers have been studied. Membranes have been cast from these polymers to study their potentiality as reverse osmosis membranes. The work has been further extended to investigated the stability of these modified CA under the influence of high temperature and γ irradiation.
Effects of enzymes and gamma irradiation on the tensile strength and morphology of poly(p‐dioxanone) fibers
Authors: Williams David F. , Chu C. C. , Dwyer J.
Published: April 2003

The objective of this study was to examine how and to what extent a new degradable polymeric fiber, poly(p‐dioxanone), used as a surgical suture material, degrades in the presence of enzymes and after γ‐irradiation. The degradation of the fiber was studied mechanically using an Instron and morphologically by SEM. Both esterase and trypsin enzymes and their corresponding buffer controls were used. The fibers were γ‐irradiated at the dosages ranging from 0 to 20 Mrad, immersed in the solution for up to 70 days, and then removed for tensile strength and morphological examinations. It was found that γ‐irradiation alone lowered the tensile strength of PDS fibers and made them more susceptible to hydrolysis. Esterase and trypsin did not accelerate the hydrolytic degradtion of this fiber to any significant level. Both γ‐irradiation and enzymes influenced the gross morphological characteristic of PDS fibers when they were subjected to hydrolysis. The most important morphological observations were the formation of surface cracks and chips on the fibers and the subsequent peeling of the chips. Enzyme‐treated PDS fibers exhibited similar morphological findings but the size of the chips was smaller. The morphological observations of PDS fibers were consistent with the tensile strength data.
Aliphatic polyester miscibility with polyepichlorohydrin
Authors: Fernandes A. C. , Barlow J. W. , Paul D. R.
Published: April 2003

Based on the behavior of the glass transition for blends of polyepichlorohydrin with various aliphatic polyesters, miscible amorphous phases are formed in all cases when the ratio of aliphatic carbons to ester groups in the repeat unit is less than 10 but more than 2. This observation includes selected polyesters with branched and saturated cyclic units in their structure. Interaction parameters deduced from polyester melting point depression were all negative and showed a minimum within this range of polyester molecular structures. The composition dependence of the observed glass transitions was found to be severely influenced by the presence of polyester crystallinity in the blend when heated through the transition region.
Preparation of tri‐O‐benzylcellulose by the use of nonaqueous cellulose solvents
Authors: Isogai Akira , Ishizu Atsushi , Nakano Junzo
Published: April 2003

A procedure has been developed for preparing tri‐O‐benzylcellulose with higher yields than 90%. In this procedure, cellulose was dissolved in a nonaqueous cellulose solvent, SO2–diethylamine (DEA)–dimethyl sulfoxide (DMSO), and then powdered sodium hydroxide was added. To the suspension thus prepared, benzyl chloride was added in four portions under heating. Chemical and physical properties of tri‐O‐benzylcellulose were studied, and tri‐O‐benzylcellulose prepared from microcrystalline cellulose powder shows the characteristic of thermotropic liquid crystal.
Curing stresses in an epoxy polymer
Authors: Srivastava A. K. , White J. R.
Published: April 2003

Curing stresses in sheets of an epoxy polymer cured at 80°C, 120°C, and 135°C have been determined using the layer removal procedure. Tensile stresses were found to be present in the interior and compressive stresses near to the surface in all samples. Very low stresses were found to be present in material cured at 80°C, with a maximum compressive stress level close to 0.5 MN/m2 and a maximum tensile stress close to 0.25 MN/m2. Higher stress magnitudes were obtained when using higher curing temperatures, with values of more than 1 MN/m2 (compressive) and 0.6 MN/m2 (tensile) recorded for specimens cured at 135°C.
Polymer composite of rigid and flexible molecules: Blend systems of poly(p‐phenylene terephthalamide) and ABS resin
Authors: Takayanagi Motowo , Goto Kohei
Published: April 2003

Homogeneous coagulant of poly(p‐phenylene terephthalamide) (PPTA) and ABS resin was obtained by pouring the dimethylsulfoxide solution of N‐sodium PPTA and ABS into acidic water. Transmission electron microscopic observation proved that PPTA was dispersed in the matrix in a form of microfibril with a diameter of 10–30 nm. The Tg of the resin component in ABS shifted to higher temperatures with increasing fraction of PPTA. Stress‐strain behavior of the polymer composite showed increased tensile modulus and strength with addition of PPTA. The transition temperature from brittle to ductile fracture, however, shifted to higher temperature resulting in lower extensibility. Incorporation of the block copolymer of PPTA and polybutadiene into ABS improved the ultimate extensibility, i.e., increased toughness was provided compared with the simple composite systems of ABS and PPTA microfibrils. Scanning electron microscopic observation showed that the polymer composite made with the block copolymer generated many crazes upon deformation, while the composite with PPTA homopolymer fractured without remarkable craze formation. Thus, a new type of thermoplastic with improved mechanical properties was obtained by use of PPTA block copolymer as compatibilizer.
Addition polyimides. IV. Effect of structure on thermal characteristics
Authors: Varma Indra K. , Sangita  , Varma D. S.
Published: April 2003

Chain extension reaction of bis(m‐maleimido phenyl) methyl phosphine oxide (BP) with 4,4′‐diaminodiphenylmethane (BP–M), 4,4′‐diaminodiphenyl ether (BP–E), 3,3′‐ and 4,4′‐diaminodiphenyl sulfone (BP–DDSm and (BP‐DDSm respectively), tris (m‐aminophenyl) phosphine oxide (BP–TAP), and 9,9‐bis(p‐aminophenyl) fluorene (BP–BAF) was carried out by refluxing 1:0.3 molar solution of BP:diamine. The melting temperature and exothermic peak associated with curing of BP decreased by such chain extension. The thermogravimetric analysis indicated more than 60% residual weight at 800°C in nitrogen atmosphere in BP–DDSm, BP–DDSp, and BP–TAP resins. These resins can be processed at low temperature and can be used for fabrication of composites with improved properties.
Preparation of spherical polymer beads of maleic anhydride–styrene–divinylbenzene and metal sorption of its derivatives
Authors: Ogawa N. , Honmyo K. , Harada K. , Sugii A.
Published: April 2003

Compounds having acid anhydride moiety have been used for starting materials for many useful derivatives. Spherical crosslinked polymer beads of porous maleic anhydride–styrene–divinylbenzene copolymer are obtained by suspension polymerization. Glycerol is found to be a preferable dispersant to make spherical beads. The beads contained 93% of the anhydride and 7% of the free carboxyls. As one of applications, the beads were hydrolyzed or reacted with anhydrous hydrazine, and the metal sorption behavior of them was examined. The hydrolyzed beads show a similar sorption manner as a conventional cation exchange resin having carboxylic acid groups, but the hydrazide beads sorbed mercury (II) selectively over a wide pH range. This investigation suggests a simple preparative method for the insoluble spherical porous beads of the maleic anhydride copolymer.
Semi‐ and fully interpenetrating polymer networks based on polyurethane–polyacrylate systems. VI. Polyurethane–poly(methyl acrylate‐co‐ethyl acrylate) semi‐1‐interpenetrating polymer networks
Authors: Hourston D. J. , Zia Y.
Published: April 2003

Dynamic mechanical and longitudinal sonic velocity measurements have been made on a series of semi‐1‐IPNs in which the network component is a polyurethane and the linear constituent a copolymer of methyl acrylate and ethyl acrylate. Dynamic mechanical analysis reveals phase separation. The shifting of the polyurethane glass transition in both the tan δ− and the E″–temperature plots indicates that some mixing occurs. The longitudinal sonic velocity results indicate that the polyurethane is present as a continuous phase in all the materials investigated.
Short silk fiber‐reinforced polychloroprene rubber composites
Authors: Setua D. K. , Dutta B.
Published: April 2003

The reinforcement of polychloroprene rubber by short silk fiber has been studied in the presence of three different dry bonding systems, viz.: (a) “cohedur RK–cohedur A–silica”; (b) “cohedur RK–cohedur A–carbon black”; (c) “resorcinol–hexamethylenetetramine–silica.” The degree of fiber–rubber adhesion of the different bonding systems follows the order (a) > (b) > (c). Scanning electron microscopy studies of tensile, tear, abrasion, and flex failed surfaces of both unfilled and fiber–filled composites containing “cohedur–silica” bonding system have also been made in order to gain an insight to the mechanism of failure.
Characterization of ethylene‐1‐butene copolymer by differential scanning calorimetry and 13C‐NMR spectroscopy
Authors: Kimura Keiichiro , Shigemura Takeo , Yuasa Sakae
Published: April 2003

Two kinds of ethylene‐1‐butene copolymers that were produced by the different procedures, that is, the slurry and the high‐pressure polymerizations, were characterized by differential scanning calorimetry (DSC) and carbon‐13 nuclear magnetic resonance (13C‐NMR) spectroscopy. The melting points of both copolymers were found to be different in spite of the same 1‐butene content. It was deduced that this phenomenon depended upon the subtly different chain structures between these two copolymers from the tetrad monomer sequence analysis by 13C‐NMR method. In addition, the behavior of the composition fractionation by temperature rising elution technique was also considered to be affected by the chain structures.
Polymerization of methyl acrylate in the presence of 2‐mercaptobenzothiazole
Authors: Dwivedi U. N. , Mitra B. C.
Published: April 2003

Azobisisobutylronitrile‐initiated polymerization of methyl acrylate was carried out in a dilatometer at 60°C for 180 min in the presence of 2‐mercaptobenzothiazole. The 2‐mercaptobenzothiazole acts as a retarder. The values of various kinetic parameters such as rate of polymerization, average degree of polymerization, inhibition constant, and Schulz's constant have been calculated for the present system.
Simulation of ARB type reversible step growth polymerization in semibatch reactors
Authors: Gupta Santosh K. , Mohan D. , Kumar Anil
Published: April 2003

The polymerization of ARB type reversible step growth polymerization in semibatch reactors has been simulated. It is assumed that the condensation byproduct W and the monomer P1 both can vaporize, but P1 is refluxed back to the reactor. Raoults law as well as Flory–Huggins theory have been used to account for vapor–liquid equilibrium. The degree of polymerization, μn, and the polydispersity index DN have been computed for various situations. The results are found to be most sensitive to the total pressure and the equilibrium constant. A limiting total pressure history PT(T) has been obtained, going below which does not help to increase μn. The final set of equations incorporate both equalities as well as inequalities, and a simple and efficient computational scheme has been suggested to solve them.
The unfolding model for the representation of the mesophase layer in composites
Authors: Theocaris P. S.
Published: April 2003

The adhesion between matrix and inclusions (fibers or particulates) in a composite material is one of principal factors characterizing the mechanical and physical behavior of the modern composite materials. All theoretical models describing these substances neglect to consider the influence of the boundary layer developed between phases during the preparation of the composite. In this paper, two versions of a theoretical model were introduced for the evaluation of this mesophase layer. It had been shown that this thin layer influences considerably the physical properties of the composite. It was assumed that the physical properties of the mesophase unfold from those of the hard‐core fibers to those of the softer matrix. Thus, a multicylinder model was assumed, improving the classical two‐cylinder model introduced by Hashin and Rosen for the representative volume element of the composite. Based on thermodynamic phenomena appearing at the glass transition temperatures of the composite and concerning the positions and the sizes of the heat‐capacity jumps there, as well as on the experimental values of the longitudinal elastic modulus of the composite, the extent of the mesophase and the mechanical properties of the composite may be accurately evaluated. These versions of model are based on a previous one concerning a multilayer model, but they are considerably improved, in order to take into consideration, in a realistic manner, the physical phenomena developed in fiber‐reinforced composites.
The effect of alkali salt on solvent–polyacrylonitrile interaction
Authors: Padhye M. R. , Karandikar A. V.
Published: April 2003

In solvent spinning of polyacrylonitrile from DMF or DMSO, it is observed that complete removal of solvent is rather difficult. It is shown that addition of Lithium salt, e.g., lithium bromide to the solution before casting a film helps in removing the solvent easily. The probable mechanism of the action of lithium salt in solvent removal is investigated, and it has been shown that the formation of coordinate linkage with the ion stops solvent bonding.
Transport and related properties of paint films. I. Composition and structure
Authors: Newey Herbert A. , Busso Charles J. , Wedgewood Alan R. , Beck Theodore R.
Published: April 2003

This is the first of a series of articles on ionic and molecular transport processes and related properties of paint films. The intention is to correlate adhesion and initiation of corrosion to these relevant physical and chemical properties. Chemical formulas and structure of three vinyl–three epoxy– and one polyurethane–paint system are given in this article. Each paint has been formulated to meet appropriate military specifications. Subsequent articles will deal with dynamic mechanical properties, small angle x‐ray scattering measurements of porosity, and transport properties.
Particle structure of PVC based on cellulosic suspension system. III. Effect of monomer refluxing
Authors: Cheng John T. , Langsam Michael
Published: April 2003

The effects of monomer refluxing on both resin properties and reactor fouling of suspension PVC have been studied in a laboratory‐scale 14‐L reactor. Process control equations were developed which related the particle properties to the reflux condenser operation by controlling the parameters of (1) the time at which refluxing is begun and (2) the rate profile of heat removal from the condenser. An operating envelope has been developed for laboratory scale operations which optimizes the cycle time of polymerization while minimizing the adverse effects on particle properties. These operating conditions may have application to production scale operations when the proper scaling factors are employed.
Novel methods for efficient estimate of intrinsic viscosity
Authors: Chee K. K.
Published: April 2003

Two novel procedures have been established to estimate the intrinsic viscosity and the Huggins constant accurately. It is shown that these numerical methods are superior to the existing models, namely the Huggins, Nagy–Kelven–Tudos, and Reilly–Van Der Hoff–Ziogas equations. This finding is attributed to the more even distribution of errors in the dependent variables of the present analyses. The viscometic data of a poly(vinyl chloride) sample in tetrahydrofuran are analyzed by the foregoing five approaches whose accuracies are compared in terms of their variances of estimates.
A rationale for the preparation of asymmetric pervaporation membranes
Authors: Mulder M. H. V. , Hendrikman J. Oude , Wijmans J. G. , Smolders C. A.
Published: April 2003

Pervaporation is carried out primarily with homogeneous membranes. An improvement in permeation rate can be achieved by using asymmetric or composite membranes. In order to maintain a high selectivity, very dense top layers are needed. The formation of asymmetric pervaporation membranes will be discussed in terms of the model proposed by our group: formation of the top layer by gelation; formation of the porous sublayer by liquid–liquid phase separation followed by gelation of the concentrated polymer phase. To obtain very dense top layers the following factors are important: the ratio of nonsolvent inflow and solvent outflow, polymer concentration, location of the liquid–liquid demixing gap, and location of the gel region. Asymmetric membranes have been prepared by varying these factors, and the obtained membranes have been tested on ethanol/water mixtures.
Studies on selective adsorption resins. XXI. Preparation and properties of macroreticular chelating ion exchange resins containing phosphoric acid groups
Authors: Egawa Hiroaki , Nonaka Takamasa , Maeda Hironori
Published: April 2003

Macroreticular cation exchange resins containing phosphoric acid groups (RGP) were prepared by the reaction of glycidyl methacrylate–divinylbenzene copolymer [or poly(glycidyl methacrylate)]beads (RG) with phosphoric acid or phosphorous oxychloride, and the adsorption behavior of metal ions on the RGP was investigated. The phosphorylation of the polymer beads could be effectively carried out by treatment of the polymer beads with 85% phosphoric acid at 80°C for 3 h. The RGP obtained from glycidyl methacrylate–divinylbenzene (2 mol %) copolymer beads showed high cation exchange capacity, salt splitting capacity, and adsorption capacity for Cu2+, Zn2+, Cd2+, Ca2+, and Ag+. On the other hand, the RGP obtained from poly(glycidyl methacrylate)beads had high adsorption capacity for Al3+, Fe3+, and UO22+. The RGP prepared by treating the RG with phosphoric acid had a higher selective adsorption for Li+ than for Na+.
Mechanisms of antioxidant action: the antioxidant activity of nitrones in polypropylene
Authors: Chakraborty Khirud B. , Scott Gerald , Yaghmour Hassan
Published: April 2003

Aldonitrones are effective melt stabilizers for polypropylene, the most effective being benzaldonitrones containing a partially hindered 4‐hydroxy group in the aromatic ring. They form nitroxyl radicals in the polymer during processing, and these and the related hydroxylamines are believed to be involved in a catalytic CBA/CBD antioxidant cycle during mechano‐ and photooxidation. During thermal oxidation (oven aging) they behave as stoichiometric CB‐D antioxidants.
Plasma polymerization of organosilicon compounds
Authors: Inagaki N. , Kondo S. , Hirata M. , Urushibata H.
Published: April 2003

Plasma polymerizations in five silicon compounds having chemical formula of (CH3)3SiXSi(CH3)3, X = none, CH2, NH, O, and S atoms, were investigated by elemental analysis, infrared spectroscopy, and ESCA. The chemical composition of polymers plasma‐polymerized was influenced by the X groups in (CH3)3SiXSi(CH3)3. Polymers, when X was S atoms, possessed no sulfur; and X was CH2 groups polymers rich in carbon and hydrogen atoms were formed. Details in chemical composition were discussed by IR and ESCA. Such differences in chemical composition reflected on gas permeability of the plasma films.
Radiation‐Induced graft copolymerization of methacrylic acid onto polypropylene fibers. IV. Thermal behavior
Authors: Mukherjee A. K. , Gupta B. D.
Published: April 2003

Thermal behavior of polypropylene‐g‐poly(methacrylic acid) fibers prepared by graft copolymerization of methacrylic acid onto polypropylene fibers, using simultaneous‐irradiation technique, was evaluated by thermogravimetric analysis, differential scanning calorimetry, and limiting oxygen index measurements. In general, the thermal properties of polypropylene fiber were markedly improved by the grafting of methacrylic acid. The inherent crystallinity of polypropylene, as deduced from DSC, did not show any change in the grafted fibers, suggesting that the grafting occurs in the amorphous region, without disrupting the crystalline part of the polymer. The LOI of grafted fibers showed an increase over the original fiber.
Diffusion/adsorption model of cellulose dyeing. II. Ordinary cellulose–direct dye system
Authors: Morita Zenzo , Tanaka Takaaki , Motomura Hiromi
Published: April 2003

The diffusion and adsorption of C.I. Direct Yellow 12 and Blue 15 in water‐swollen ordinary cellophane sheets were examined at various ionic strengths. The concentration dependence of apparent diffusion coefficients, Dc, for these dyes was obtained from the diffusion profiles in the substrate, which were measured by the use of the cylindrical film roll method. The decrease of apparent porosity with an increase in the amounts of adsorption was observed. To explain the diffusion/adsorption behaviors of these systems, a variable porosity model was proposed and was applied to analyze the concentration dependence of Dc's. The diffusion/adsorption behaviors of these dyes could be quantitatively described by this model at relatively low ionic strengths. At higher ionic strengths and/or lower values of C, i.e., at the large values of Cim/Cm, where the C's are the concentrations of immobilized (suffix im) and mobile (suffix m) species, it needed to introduce the concept of dynamic equilibria which occurred simultaneously with diffusion but deviated from the true equiliblia measured by the adsorption experiments.
A study of the drawing behavior of polyvinylidene fluoride
Authors: Humphreys J. , Ward I. M. , Nix E. L. , McGrath J. C. , Emi Thorn
Published: April 2003

The drawing behavior of different molecular weight PVDF grades has been investigated over the temperature range 140–160°C, with particular reference to the production of material with enhanced mechanical and electrical properties. Lower molecular weight grades, which have been subjected to a slow‐cooled rather than a quenched moulding procedure yield higher Young's moduli when drawn to a given draw ratio. X‐ray diffraction measurements have demonstrated that the crystalline regions of specimens drawn to high draw ratios under these conditions consist predominantly of the piezo‐ and pyroelectric form I phase. The relationship between the proportion of from I phase and the final drawing stress has been shown to be unique over the temperature range investigated, irrespective of molecular weight and thermal processing history.
Phase behavior of polyarylate blends
Authors: Robeson L. M.
Published: April 2003

Melt mixtures of a polyarylate based on bisphenol A and tere/isophthalates were made with poly(ethylene terephthalate), several cyclohexane dimethanol‐based polyesters, polycarbonate, and the poly(hydroxy ether) of bisphenol A. The phase behavior was determined using classical methods. With minimum time and temperature exposure, polyarylate exhibits phase separation with poly(ethylene terephthalate) (PET) at >30 wt % PET. With moderate time and temperature exposure, adequate ester exchange occurs with polyarylate/PET blends to yield single‐phase behavior. The activation energy of the ester‐exchange reaction was determined to be 37.0 kcal/mole.

Under minimum time and temperature exposure conditions, miscibility of polyarylate with three different cyclohexane dimethanol‐based polyesters was observed. A polyarylate‐polycarbonate 50:50 mixture was shown to be phase separated under minimum mixing conditions but capable of exchange reactions to yield single‐phase behavior with proper time and temperature exposure. Likewise, a 70:30 polyarylate‐poly(hydroxy ether of bisphenol A) blend was phase separated as mixed, but with further elevated temperature exposure, a cross‐linked single‐phase system resulted.

The density versus composition of the polyarylate‐PET blends was linear with the phase‐separated systems but exhibited a slight densification with the miscible systems produced by higher temperature exposure. The glass transition of the miscible polyarylate‐polyester blends exhibited a significant deviation (lower) than predicted by a linear or Fox equation prediction. This was attributed to the low value of ΔCp (specific heat difference between the glass and rubber states) of polyarylate as noted by the Couchman equation to be a major factor in the Tg versus composition relationship. The optical characteristics of the blends paralleled the observed phase behavior as single‐phase blends were all transparent (in the amorphous state) whereas phase‐separated blends were translucent to opaque. These results clearly demonstrate the importance of ester‐exchange or transesterification reactions in the phase behavior of blends of polymers capable of these reactions.
Morphology of polyurethane–isocyanurate elastomers
Authors: Wang C. L. , Klempner D. , Frisch K. C.
Published: April 2003

The dynamic viscoelastic properties and thermal transition behavior of reaction injection molding (RIM) and cast polyurethane—isocyanurate elastomers have been studied as a function of various segments (soft and hard urethane, and hard isocyanurate) content. RIM and cast elastomers were prepared at different concentrations of soft and hard urethane, and hard isocyanurate segments. RIM elastomers with the higher isocyanate index (lower hard urethane and greater isocyanurate segment content) displayed an unchanged Tg (glass transition temperature of soft segment) and increasing Tgh (glass transition temperature of hard segment) related to the hard urethane and isocyanurate segments. This is due to the phase separation between the soft and the hard segments. Cast elastomers synthesized from the higher amount of 1,4‐butanediol (greater hard urethane and less hard isocyanurate segment content) showed an increasing Tgs, decreasing Tgh of hard urethane segments, and an unchanged Tgh of isocyanurate segments. This is related to the phase mixing between the soft and the hard urethane segments and the phase separation of hard isocyanurate and hard urethane segments.
Radiation‐induced emulsion ploymerization of vinyl acetate in a pilot plant reactor II. Kinetics
Authors: Challa R. R. , Drew J. H. , Stahel E. P. , Stannett V.
Published: April 2003

The recycle flow reactor pilot plant, described in Part I of this series, has been used to study some kinetic and other features of the emulsion polymerization of vinyl acetate. In particular, the dependence of the rate on the emulsifier concentration was determined and found to be 0.38 ± 0.09. Separate batch experiments were in reasonable agreement as 0.29 ± 0.10. The effects of temperature, dose rate, and agitation rate were also determined and were in agreement with most of the literature values.