bluuebunny/crossref_metadata_2025 huggingface dataset:
Trivalent manganese chelate‐initiated graft copolymerization of methyl methacrylate onto silk fibers
Authors: Samal R. K. , Suryanarayana G. V. , Dash P. C. , Panda G. , Das D. P. , Nayak M. C.
Published: April 2003

The graft copolymerization of methyl methacrylate onto silk fibers was investigated in aqueous solution using Mn3+ acetyl acetonate [Mn(acac)3] as initiator. The rate of grafting was determined by varying monomer, acidity of medium, temperature, and reaction medium. The graft yield increases significantly with increase of [Mn(acac)3] concentration up to 0.01M, and with further increase of [Mn(acac)3] the graft yield decreases. The effect of the increase of monomer concentration brings about a significant enhancement in the graft yield, and with further increase the graft yield decreases. The rate of reaction is temperature dependent; with increasing temperature, the graft yield increases. Among the solvent composition studied, a water/solvent mixture containing 10% of the solvent seems to constitute the most favorable medium for grafting, and, with further increase of solvent composition, the graft yield decreases. The effect of some inorganic salts, organic solvents, and complexing agents has been investigated.
Rubber‐modified polystyrene impact as a function of flame‐retardant additive solubilization
Authors: Sprenkle W. E. , Southern J. H.
Published: April 2003

Thermal optical analysis (TOA) is employed to study the solubilization of organic flame‐retardant additives in high‐impact polystyrene. The TOA approach (1) indicates the minimum temperature at which solubilization will occur; (2) yields information on how the composite will process; and (3) can be used to generate an equation that describes the kinetics of solubilization. Multiaxial impact strength increases proportionally as additive solubilization increases. The fundamental significance of the kinetic equation is discussed. Other applications of TOA are suggested.
Rayleigh–brillouin scattering from reacting epoxy resins: Comparison with torsional braid analysis
Authors: Kondo Shingo , Igarashi Takashi , Nakamura Tsutomu
Published: April 2003

The rheological study for isothermal curing processes of two kinds of epoxy/amine systems made by Rayleigh–Brillouin spectroscopy was compared with torsional braid analysis. The Brillouin shift increased with the increase in the density during the process. The intensity ratio of Rayleigh line to Brillouin lines (LP ratio) increased remarkably in accordance with the onset of gelation measured by extraction. The increase of scattered light suggests that some kind of density fluctuation of the order of the light wavelength takes place prior to the gelation. The longitudinal elastic modulus and the attenuation of sound in the hypersonic region changed monotonically from the start of measurement and almost leveled off after the transition to the glassy state determined by dilatometry. While the relative shear modulus in a low‐frequency region (0.1 ∼ 1 Hz) was not sensitive to the onset of gelation, it was markedly affected by the approach to the glassy state.
Ultradrawing and crystallization of isotactic polystyrene and blends with atactic polystyrene
Authors: Wang Li‐Hui , Porter Roger S.
Published: April 2003

Pure isotactic polystyrene (iPS, Mw = 8.89 × 104, Mw/Mn = 4.89) and its blends with an atactic polystyrene (aPS, Mw = 3.9 × 105, Mw/Mn < 1.13) were subjected to draw by solid state coextrusion at 127°C within polyethylene. The content of amorphous iPS in these blends was varied from 100 to 24.4 wt %. The extent of draw‐induced crystallization was found to depend on the draw ratio and on iPS concentration. The blend with 24.4% iPS was coextruded in two stages. The highest effective draw ratio (EDR) was 7.6 and 13.7 for one‐ and two‐stage draw, respectively. The highest crystallinity of 33.2% was obtained for pure iPS at the maximum EDR of 7.6. Considerable crystallinity was induced in blends, requiring successively higher draw ratio to reach similar crystallinity with increased aPS content. The tensile modulus increased from 1.5 to 3.2 GPa, independent of iPS concentration. Thermal shrinkage results indicate that the elastic recovery of draw in the blends is near quantitative for an EDR < 8. For pure iPS, extrudate elastic recovery was dramatically altered by the draw‐induced crystallinity.
Copolymerization of pentachlorophenyl acrylate with vinyl acetate and ethyl acrylate. Polymer‐bound fungicides
Authors: Pittman Charles U. , Stahl G. Allan
Published: April 2003

Copolymers of pentachlorophenyl acrylate (M1) with both vinyl acetate and ethyl acrylate were prepared (in benzene at 60°C initiated by t‐butyl peroxypivalate) at a variety of M1/M2 ratios. The reactivity ratios for the vinyl acetate (M2) copolymerizations were r1 = 1.44 and r2 = 0.039, while for ethyl acrylate copolymerizations r1 = 0.21 and r2 = 0.88. The glass transition temperatures were obtained as a function of the M1/M2 ratio. The values of Tg for the copolymers fell between those of poly(pentachlorophenyl acrylate) and either poly(vinyl acetate) or poly(ethyl acrylate). A series of bulk copolymers with low pentachlorophenyl acrylate content were studied as biocidal coatings using accelerated growth agar dish tests inoculated with Aspergillus sp., Pseudomonas sp., Alternaria sp., and Aureobasidium pullulans. The copolymers retarded or prevented growth but did not give a zone of inhibition around the coatings. Pentachlorophenol, when added to coating polymers, did exhibit a zone of inhibition due to migration of this biocide into the agar medium.
Correlation between the mechanical behavior and relaxation processes in the plastically deformed polycarbonate
Authors: Hong Jauwhei , Brittain J. O.
Published: April 2003

The low‐temperature β relaxation has been studied via thermally stimulated depolarization current (TSD) method for polycarbonate that had been cold‐rolled and subsequently undergone the α′ relaxation at 70°C as a function of time. It has been found that the intensity of the β process increased as the annealing at 70°C increased. The analysis of the activation energy spectrum associated with the β relaxation indicated that the enhancement in the β intensity was due to the liberation of local dipoles from their aligned orientation as a result of undergoing the α′ relaxation process. Tensile flow curves have also been determined for the same set of specimens. Similar enhancement was also observed in the yield stress behavior. In view of the good correlation between the mechanical property and the structural change revealed by the relaxation study, it was concluded that the variation of the yield stress and the work‐hardening in the rolled polymer was primarily associated with those parts of the chain that had been disoriented from their frozen‐in conformations.
Morphological effects on the bulk polymerization of trioxane in the solid state by γ‐radiation
Authors: Kiss Gabor , Kiss Klara , Kovacs A. J. , Wittmann J. C.
Published: April 2003

The solid‐state polymerization by γ‐radiation and postpolymerization of bulk samples of trioxane has been investigated. Different thermal treatment results in radically different initial morphologies of the melt‐crystallized trioxane which in turn have a profound influence on the yield and morphology of the resulting poly(oxymethylene) (POM). The polymerization yield increases in the following series: melt‐crystallized trioxane with an “opaque” (small grains) morphology, as‐grown needles, trioxane with a “quasi‐transparent” morphology, and finally thermally oriented crystals. Furthermore, little additional POM is formed during repeated polymerization cycles. The observation of an extensive nodulation of the polymer fibrils when the yield is high is consistent with a multiple‐stage growth model for the solid‐state polymerization of trioxane.
Influence of tacticity and sorbed water on the material properties of poly(N,N'‐dimethylacrylamide)
Authors: Mohajer Y. , Wilkes G. L. , McGrath J. E.
Published: April 2003

The effects of variation in tacticity on the thermal, morphological, stress–strain and stress–relaxation properties (both in the dry state and 140°C, and at a RH of 72% and ambient temperature) were evaluated for a series of homopolymers of poly(N,N‐dimethylacrylamide). In the range of 19 to 23% tacticity (isotactic content), a fundamental change in the level of crystallinity and morphology occurs for this series of polymers which in turn greatly affects the above‐mentioned properties. Below 19% tacticity, the polymers are amorphous, but above 23% they are distinctly semicrystalline. Sorbed water plasticizes all these polymers, but the influences of the water on the stress–strain properties is greatest for the amorphous polymers, where the relative sorption of water is also highest.
Catalysis of the reaction between isocyanates and protonic substrates. I. Metal salt–amine complexes as catalysts in the polyurea foaming process
Authors: Borsus J. M. , Jérôme R. , Teyssié Ph.
Published: April 2003

Tertiary amines and metal [Cu(II), Zn(II)] salts exhibit a synergistic effect in the catalysis of the isocyanate water reaction. The amino complexes of zinc and copper salts display a very large versatility in defining the most suitable formulations for the polyurea foam production. The foaming process is indeed controlled by the nature and the composition of these new catalytic combinations; kinetics of foaming and textural characteristics of final foams are easily modified in that way.
Condensation products from imidobis(sulfuryl chloride)
Authors: Argyropoulos D. , Lenk R. S.
Published: April 2003

A study of model compounds and polycondensation products derived from imidobis(sulfuryl chloride) (IBSC), HN(SO2Cl)2, has been carried out and their structures determined. The model compounds were reaction products of IBSC with aniline or ethyl alcohol. Polymeric products were obtained by polycondensations with (1) p‐phenylenediamine and (2) 2,2‐bis(4'‐hydroxyphenyl)‐propane. The products were characterized by elemental analysis, infrared, NMR, DSC, TGA, and viscometry data.
Block copolymers obtained by free radical mechanism. II. Butyl acrylate and methyl methacrylate
Authors: Gunesin Binnur Z. , Piirma Irja
Published: April 2003

Block copolymers were synthesized using methyl methacrylate and butyl acrylate as the monomers and a multifunctional initiator, di‐t‐butyl 4,4'‐azobis(4‐cyanoperoxyvalerate). The polymerizations for the formation of the block copolymers were carried out in two stages. First the poly(methyl methacrylate) polymeric initiator was synthesized and isolated. In the second stage, the thermallyactivated azo group in the polymer backbone initiated the polymerization of butyl acrylate. Upon termination by combination a tri‐block results. Selective solvent fractionation was used to separate the block from the homopolymers.
Grafting vinyl monomers onto cellulose. IV. Graft copolymerization of methyl methacrylate onto modified cellulose using peroxydiphosphate as the initiator
Authors: Lenka Subasini , Nayak Padma L. , Mishra Munmaya K.
Published: April 2003

The graft copolymerization of methyl methacrylate onto modified cellulose was studied at 60° causing peroxydiphosphate as the initiator. The rate of grafting in case of different modified cellulose was determined by varying peroxydiphosphate, monomer, nature of substrate, and temperature. The molecular weight of the isolated polymer has been determined, and the mechanism of grafting is discussed.
Modification of polyvinylchloride in solution or suspension by nucleophilic substitution
Authors: Marian S. , Levin G.
Published: April 2003

Nucleophilic displacement of chlorine from polyvinylchloride (PVC) suspended either in water or in solution can be achieved using a nucleophile such as a sodium thiolate (RS−, Na+). The nucleophilicity of the salt increases if an ether linkage exists in a β position to the thiol group [RO(CH2)2S−, Na+]. Addition of a solvent such as cyclohexanone (which is a good solvent for PVC) to the slurry increases substantially the degree of substitution. Elemental analysis shows that every chlorine displaced from the polymer is replaced by a thiolate group; thus almost no dehydrochlorination occurs. It is possible to obtain by this method a grafted polymer in which 33% of the chlorine atoms are replaced by the β‐ether thiolate group. The resulting polymer behaves like an internally plasticized PVC. The higher the degree of substitution of chlorine, the greater the flexibility of the grafted polymer is. Other compounds, such as lauryl thiolate and diethyl dithiocarbamate, also were used as nucleophiles, the latter one resulting in a brittle crosslinked polymer whenever sulfur was above 2%. Grafting of polytetrahydrofuran from PVC also was achieved using tetrahydrofuran as solvent and silver‐perchlorate as catalyst. The resulting flexible grafted polymer is believed to consist of longer chains of polytetrahydrofuran grafted from few displaced chlorine atoms along the PVC chain.
Rate characteristics for the reaction of carboxyl‐modified polyamide with potassium hydroxide
Authors: Healy E. M. , Ramsley A. O. , Herz M. L.
Published: April 2003

Nylon 66 fiber, carrying 2.0 meq/g of carboxyl groups from radiation grafting of acrylic acid, was found to display chemical kinetics strongly first order with respect to the potassium hydroxide. The apparent rate constant k' remains nearly unchanged as the initial bath pH is varied from 8.3 to 10.5. At this point, the value of k' drops sharply, and continues to drop as the initial pH is increased. This discontinuity is attributed to a previously reported morphological transition indicated by a break in titration data at the corresponding equilibrium point of pH 9.2.
Influence of external environments on fracture toughness of epoxy resin
Authors: Mizutani K. , Iwatsu T.
Published: April 2003

Crack propagation in an epoxy resin in the presence of organic solvents was investigated. Fracture toughness (KIC, a critical stress intensity factor) of the epoxy resin in various external environments was measured using a double cantilever beam specimen. Fracture toughness for initiation (KICi) of the resin in the presence of organic solvents was larger than that in the absence of solvents, and the epoxy resin showed a minimum value of KICi in the presence of the organic solvent whose solubility parameter was about 11 (cal/cm3)1/2. This was due to large plastic deformation at a crack tip and the yield strength was lowered by exposure to organic solvents. The former increases KIC, while the latter decreases KIC. Fracture surfaces of the resin fractured in solvents suggest that a crack grew slightly when accompanied by a large plastic deformation, and then propagated at high speed.
Prediction of second virial coefficients from intrinsic viscosities
Authors: Kok Chong Meng , Rudin Alfred
Published: April 2003

One of the most readily available characteristics of a polymer sample is its intrinsic viscosity in a particular solvent. This datum can often be estimated reasonably from a single relative viscosity measurement. A number of theories permit the calculation of the second virial coefficient of a polymer/solvent mixture given the intrinsic viscosity and polymer molecular weight. The intrinsic viscosity of the polymer under theta conditions is also needed, but this can be estimated, if necessary, from the molecular weight. This article compares the efficiencies of various alternative models for the prediction of second virial coefficients of a series of polymers and solvents. The most effective technique for this purpose first calculates the concentration‐dependent equivalent hydrodynamic volume of a solvated polymer coil. This value is used with a primitive statistical mechanical theory for virial coefficients of hard‐sphere suspensions to calculate the osmotic pressure or turbidity of the polymer solution. These simulated experimental values are fitted with a least‐squares line as in the real experiment, and the second virial coefficient is derived from the slope. The computations are relatively simple; the average deviation between observed and predicted virial coefficient was less than 16% for a variety of polymer types, molecular weights, and solvents.
Biodegradation of gelatin–g‐poly(ethyl acrylate) copolymers
Authors: Kumar G. Sudesh , Kalpagam V. , Nandi U. S. , Vasantharajan V. N.
Published: April 2003

Gelatin‐g‐poly(ethyl acrylate) copolymers were prepared in an aqueous medium, using K2S2O8 initiator. The composition of the graft copolymers was dependent upon temperature and duration of the reaction. The number of grafting sites was small and molecular weight of the grafted poly(ethyl acrylate) branches was high. Three copolymer samples with grafting efficiencies of 33.3%, 61.0%, and 84.0%, were tested for their microbial susceptibility in a synthetic medium employing a mixed inoculum of Bacillus subtilis, Pseudomonas aeruginosa, and Serratia marcescens and the percent weight losses were 12%, 10.1%, and 6.0%, respectively, after 6 weeks of incubation. The extent of degradation seems to decrease with increasing grafting efficiency. There was initial rapid weight loss accompanied by the exponential increase in bacterial population and pH of the culture medium during the first week. The nitrogen analysis also showed the utilization of the polymer. A parallel set of experiments, carried out by employing the samples as the only source of both carbon and nitrogen, showed a marginal but definite increase in the utilization of the polymer.
Poly(vinyl chloride)–polyol (AB)x block copolymers: Synthesis, characterization, and mechanical properties
Authors: Laverty John J. , Gardlund Zack G.
Published: April 2003

Poly(vinyl chloride)–polyol (AB)x block copolymers have been prepared by the condensation polymerization of low‐molecular‐weight hydroxy‐terminated poly(vinyl chlorides) (PVC) and diisocyanate‐capped polyester and polyether diols. The difunctional poly(vinyl chlorides) were synthesized by ozonization of commercial resin followed by metal hydride reduction. The (AB)x block copolymers, which contained 3000 or 4300 molecular weight PVC block sizes and 1000–2000 molecular weight polyol segments, had a wide range of mechanical properties, depending on overall polymer structure. Tensile strengths ranged from 7.8 to 31.5 MPa, elongations from 125% to 610% and torsional stiffness temperatures (Tf) from 25°C to −22°C.
The radiation crosslinking of poly(vinyl chloride) with trimethylolpropane trimethacrylate. I. Dose dependence and the effects of thermal treatment
Authors: Bowmer T. N. , Davis D. D. , Kwei T. K. , Vroom W. I.
Published: April 2003

The radiation crosslinking of poly(vinyl chloride), PVC, with trimethylolpropane trimethacrylate, TMPTMA, has been examined. The polyfunctional TMPTMA undergoes rapid polymerization incorporating the PVC into a three‐dimensional network. The kinetics and mechanism of these crosslinking reactions were studied with particular reference to dose dependence and thermal treatment. The gel was rapidly formed with a TMPTMA polymerization rate greater than that of the PVC grafting reaction. Only 30–40% of the available bonds were used in the initial polymerization. The remaining 60–70% of the double bonds predominantly react in the final stages of crosslinking (80–100% gelation). The macroscopic properties (e.g., solubility, glass transition temperatures, mechanical characteristics, etc.) of the PVC–TMPTMA blend are discussed in terms of the molecular crosslinking mechanism. The effect of thermal treatment, during and after irradiation, on the reaction rates and mechanism is examined.
Study of domain structure in linear and crosslinked polyurethanes using pulsed proton NMR
Authors: Assink R. A. , Wilkes G. L.
Published: April 2003

Pulsed proton magnetic resonance was used to study the domain structure of a series of polyurethanes which had been crosslinked to various degrees at 210°C. The difference between segmental mobility of the hard and soft phases decreases with crosslinking. The fraction of rigid segments in the linear material decreases in two distinct stages as the temperature increases, while the fraction of rigid segments in the crosslinked material decreases in a continuous fashion as the temperature increases. Crosslinking also decreases the rate of domain formation following thermal treatment. These effects are attributed to the inability of the segments in the crosslinked material to completely segregate into domains.
Factors affecting initial bond strength in solvent‐based contact adhesives
Authors: Kozakiewicz Janusz , Kujawa‐Penczek Bibianna , Penczek Piotr , Puton Krzysztof
Published: April 2003

Novel interpretation is given for the development of initial bond strength maximum in solvent‐based contact adhesives at particular elastomer/resin ratios in the adhesive films. Complex relations between initial bond strength, tack of adhesive films, adhesive open time, solvent retention, and resin content in adhesive films are discussed. These results are based on data using polychloroprene adhesives modified with butylphenolic resins and also on previous studies with other contact adhesives. It is suggested that solvent retention is the main factor affecting initial bond strength in solvent‐based contact adhesives.
Photooxidation of the surfaces of polyphenylene oxide and polysulfone
Authors: Peeling James , Clark David T.
Published: April 2003

Changes in the composition and structure of the surfaces of polyphenylene oxide (PPO) and polysulfone caused by UV photooxidation are followed using ESCA. The surface stoichiometry of PPO changes from C8O1 to C8O4.8 on photooxidation, the oxygen being added in the form of carbonyl and especially carboxyl groups. Surface photooxidation is rapid, the ESCA spectra showing substantial changes after a few minutes of irradiation, and no further changes being detected after 10 h of reaction. The surface photooxidation of polysulfone occurs in three stages. In the first 2 h rapid oxidation takes place at carbon atoms, the levels of C—O, carbonyl, and carboxyl groups increasing at comparable rates. This is followed by slower oxygen incorporation up to 15 h of reaction, during which time carbonyl and carboxyl levels increase and oxidation of the sulfone sulfur is observed. Some degradation occurs as groups containing carbon and oxygen are lost from the surface. Further oxidation then produces a decrease in the surface levels of C—O and carbonyl groups, and further degradation. The photooxidized surface has a stoichiometry of C10O6S, compared with C27O4S in the unreacted polymer.
Polyimide structure–property relationships. III. Polyimides from multi‐ring diamines
Authors: Bell Vernon L. , Kilzer L. , Hett E. M. , Stokes George M.
Published: April 2003

The effects of increasing the distance between, and varying the isomeric positions of, the amine groups on the glass transition temperatures of aromatic polyimides were studied in order to investigate routes to improve processability. A number of isomers of three‐ and four‐ring benzenoid diamine systems were polymerized with 3,3′,4,4′‐benzophenone tetracarboxylic acid dianhydride to poly(amic acids), which were converted to polyimides. The use of methylene and carbonyl groups to connect the benzene rings of the diamines, and in one case the dianhydride, afforded a comparison of the thermomechanical properties of the polyimides to those prepared from diphenylmethane‐ and benzophenone‐diamines, respectively. Generally, the dilution of the imide content by the insertion of benzylene and benzoylene segments into the diamines significantly reduced the glass transition temperatures, with the benzylene group being more effective in that respect than the benzoylene. However, there was evidence that the position isomerism (ortho, meta, para) of the amine groups was more influential in affecting the glass transition temperatures of aromatic polyimides than was the dilution of the imide content.
A reinvestigation of parabanic acid–formaldehyde polymerization
Authors: Cassidy Patrick E. , Fawcett Newton C. , Thomas Richard W.
Published: April 2003

An earlier paper reported the synthesis of derivatives of parabanic acid, mono‐ and dimethylol parabanic acid, and their polymerizations with themselves and with aqueous formaldehyde. The study is reported herein to clarify that work. The reported synthesis of monomethylol parabanic acid was not reproducible. Identical low‐molecular‐weight polymers were obtained from the condensation of parabanic acid with formalin and from the self‐condensation of dimethylol parabanic acid. The final polymer contains a little of the original parabanic acid and a large amount of the condensation product from a ring opening byproduct. Commonly, two products are possible, a soluble one at lower reaction times and temperatures and an insoluble one at longer times and temperatures. Films cannot be formed by solvent casting or heat pressing. Elemental analyses and infrared spectra show that the actual products are not of the structure originally proposed.
Miscible blends of poly(styrene‐co‐allyl alcohol) with poly‐ϵ‐caprolactone
Authors: Barnum R. S. , Goh S. H. , Paul D. R. , Barlow J. W.
Published: April 2003

Based on the single, composition‐dependent glass transition criterion, poly‐ϵ‐caprolactone (PCL) was found to be miscible with each of four poly(styrene‐co‐allyl alcohol) (SAA) copolymers with hydroxyl contents between 1.3 and 7.7 wt %. Melting point depression of the PCL in the blends was used to evaluate the blend interaction parameter B for each miscible system. The parameter B was found to be negative and to vary with copolymer composition in a way that suggests that an optimum density of alcohol moieties in the copolymer exists for achieving maximum interaction with PCL.
Vapor sorption characteristics of condensable hydrocarbon vapor in low‐density polyethylene
Authors: Ghosh S. K.
Published: April 2003

Sorption characteristics of vapors of pure hydrocarbon and their binary mixtures in low‐density polyethylene were studied under various conditions of temperature and pressure. A new apparatus devised and utilized for the determination of composition of sorbed vapor in case of binary mixtures is described. The study demonstrates the effect of the presence of one component within the polymer on the sorption of another and also the occurrence of selectivity in sorption.
Electrodeposition of polymers from nonaqueous systems. I. Polyimides: Some deposition parameters
Authors: Alvino William M. , Scala Luciano C.
Published: April 2003

The yield and quality of an electrophoretically deposited polyimide are strongly dependent upon a number of parameters that are closely related to the formulation and characteristics of a basic nonaqueous electrophoretic emulsion. Such parameters, which have been optimized for one specific polyimide, are solvent/precipitant ratio, type and concentration of surfactant, emulsion preparation sequence, apparent pH, and solids content.
Particle size dispersion during latex growth
Authors: Cauley Donald A. , Thompson Robert W.
Published: April 2003

The evolution of the latex particle diameter distribution during batch emulsion polymerization is investigated, with emphasis on changes in the breadth of the size distribution. A model utilizing a surface area‐dependent volumetric growth rate of a single particle results in a time‐invariant standard deviation of the size distribution during periods of particle growth only. This behavior is reconciled with some experimental observations by considering the occurrence of particle nucleation during some part of the growth interval. Conclusions based on the results of the model suggest that higher inhibitor and low emulsifier concentrations favor narrow particle size distributions.
Graft copolymerization of methyl methacrylate onto wool in presence of vanadyl sulfate–potassium bromate in aqueous medium
Authors: Subhan Jahanara , Saccubai S.
Published: April 2003

Graft copolymerization of methyl methacrylate onto wool was studied in the presence of vanadyl sulfate and potassium bromate. The experimental results suggested that the wool radicals produced in the reaction initated the graft copolymerization and that the graft polymer radicals terminated by mutual combination. An appropriate kinetic scheme was proposed and the rate and energy parameters were evaluated. Alkaline solubility, dye uptake, and tensile strength of the wool samples were determined before and after grafting.
Studies on synthetic‐polymer plates with high surface energy. II. Diethylene glycol bis(allyl carbonate)–unsaturated carboxylic acid system
Authors: Ohtsuka Yasuji , Kaneko Norio
Published: April 2003

Polymer plates with high surface energy were prepared by the procedure described in the previous paper, using diethylene glycol bis(allyl carbonate) as a substrate polymer and acrylic acid or methacrylic acid as a hydrophilic monomer. By the alkali treatment (immersing in an aqueous 0.1N NaOH solution for 2 h), the resulting polymer plates had good water wettability (contact angle for water = 10°) and sufficient mar resistance (the scratching hardness = 45–50 g) in a dry state, and their clarities were higher than those for DAP systems previously reported. The surface densities of carboxyl groups on the polymer plate estimated by use of the McBain's equation were 0.18–0.46 molecule/Å2.
Carbanilation of cellulose in the paraformaldehyde–dimethyl sulfoxide solvent system
Authors: Miyagi Yoshifumi , Young Raymond A.
Published: April 2003

Methylol cellulos carbanilate (methylol cellulose phenylcarbamate) was prepared under homogeneous conditions with phenylisocyanate following the dissolution of cellulose into the paraformaldehyde–dimethyl sulfoxide system. Previously reported procedures were utilized to control the oligo‐oxymethylene side chain length of the dissolved cellulose. Methylol cellulose carbanilates with different side chain lengths were characterized by infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, and differential scanning calorimetry. The homogeneous carbanilation reaction was found to be completed with a degree of substitution of around 2.4 within 3 h at room temperature, which is substantially faster than heterogeneous carbanilation. Methylol cellulose carbanilates were found to have lower heats of decomposition (23.5–32.2 kcal/mol, depending upon the side chain length) and lower heats of decomposition temperatures (236°C) under air compared with conventional cellulose carbanilate. This suggests that the decomposition mechanism of the methylol cellulose carbanilate is through decomposition of the oligo‐oxymethylene side chains, while cellulose carbanilate decomposes by rupture of the cellulose carbamate linkage.
Effect of plasma treatments on the steam‐sour gas resistance and lubricity of elastomers
Authors: Arnold C. , Bieg K. W. , Cuthrell R. E. , Nelson G. C.
Published: April 2003

Elastomers are widely used in drilling and logging applications as static seals such as casing packers and dynamic seals such as o‐rings for drill bits. Static seals often fail in service because of thermochemical degradation due to the combined effects of steam and sour gas at elevated temperatures that are characteristic of deep wells. Dynamic seals frequently fail because of abrasive wear that occurs even at the low temperatures that prevail in shallow wells. We have shown that improved steam–sour gas resistance of a fully formulated ethylene–propylene rubber at elevated temperatures can be achieved by coating the rubber with a thin film of plasma polymerized tetrafluoroethylene. Thus, no change in the mechanical properties of the coated rubber was observed after exposure to steam and sour gas at 275°C for 48 h. In contrast, the shear modulus of the uncoated rubber increased by 96% after the same exposure. While the effectiveness of the fluorocarbon coating decreased at longer exposure times, short‐term protection of elastomers could be beneficial in certain logging operations. It was also found that the coefficient of friction of a nitrile rubber (Buna N) was reduced by 20% after treatment with a carbon tetrafluoride plasma. This enhanced lubricity could lead to better wear characteristics in conventional drill bits where the seal is in contact with a moving metal surface. The surfaces of the plasma treated elastomers were characterized by water contact angle, scanning electron microscopy, and electron spectroscopy for chemical analysis.
High performance electron negative resist, chloromethylated polystyrene. A study on molecular parameters
Authors: Imamura Saburo , Tamamura Toshiaki , Harada Katsuhiro , Sugawara Shungo
Published: April 2003

High sensitivity and high contrast electron negative resist, chloromethylated polystyrene (CMS) was developed for direct writing electron beam lithography with 1‐μm resolution. The resist shows excellent lithographic performances such as high plasma‐etching durability and negligible “post polymerization effect”. A series of CMS covering a wide range ofM̄w, 6,800–560,000, were synthesized by the chloromethylation of nearly monodisperse polystyrenes. The effects of molecular parameters on sensitivity and resolution were investigated. The chloromethylation remarkably improved the reactivity of polystyrene, but which was saturated above 40% of chloromethylation ratio. About 100 times higher sensitivity could be achieved as compared with the starting material. As the increase of chloromethylation ratio (CR) gradually broadened the molecular weight distribution (MWD), the optimum CR was evaluated to be about 40%. In the above range ofM̄w, the sensitivity varies from 39 to 0.4 μC/cm, whereas the γ‐value varies from 3.0 to 1.4. A sharp edge profile was obtained in developed pattern of CMS resist because of its relatively high glass‐transition temperature (68–115°C) compared with commercial resists and the suitable selection of a developer. The resolution of CMS was compared with the structually related polymers synthesized from polystyrene with a broader MWD or vinylbenzylchloride and poly(chloroethylvinylether) (CEVE). These polymers show significantly lower resolution than CMS, which indicates the importance of MWD andTgin electron negative resist.
Effects of various parameters in differential scanning calorimetry of hydrogen‐peroxide‐treated lignocellulose
Authors: Nguyen Tinh , Zavarin Eugene , Barrall Edward M.
Published: April 2003

Differential scanning calorimetric (DSC) analyses of mixtures of hydrogen peroxide and lignocellulosic materials have been performed. The influence of chamber atmosphere composition, heating rate, pinhole size, lignocellulose particle size, and hydrogen peroxide‐to‐lignocellulose ratio were examined. With the exception of particle size, the variables produced significant effects on the DSC curves. These effects were mainly connected with changes in the atmosphere surrounding the sample, sample density, heat capacity, and heat conductance.
Effects of 6‐anilino‐1,3,5‐triazine‐2,4‐dithiol, zinc stearate, and barium stearate on the thermal stabilization of PVC
Authors: Mori Kunio , Kikuchi Isao , Nakamura Yoshiro
Published: April 2003

Individual action and synergistic effect in the combination of 6‐anilino‐1,3,5‐triazine‐2,4‐dithiol (AF), zinc stearate, and barium stearate on the color stabilization of PVC were investigated. In this system, AF selectively reacts with allylic chlorine atoms in PVC. Consequently, unstable allylic chlorine units were converted to thermally stable allylic structures, thus retarding the development of polyene sequences. Zinc stearate accelerated the reaction of AF with allylic chlorine atoms in PVC, forming the zinc salts of AF (AFZnSt, StC1–H35COO) by reacting with AF. Barium stearate reacted with ZnCl2 which is formed in the above reaction to give St2Zn and BaCl2. Consequently, barium stearate led to the selective reaction of AF with allylic chlorine atoms in PVC and the remarkable retarding effect of discoloration of PVC.
ESR study of radiation‐induced polymerization of styrene adsorbed on silica gel
Authors: Shimada Machiko , Nakamura Yoshio , Kusama Yasuo , Udagawa Akira , Takehisa Masaaki
Published: April 2003

The effect of the specific surface area of silica gels on the radiation‐induced polymerization of styrene adsorbed on silica gel was studied by ESR. The same radicals were generated on the silica gels regardless of the specific surface area, but the stability of the radicals at room temperature depended on the specific surface area. This means that the decay of the radicals proceeded mainly on the surface of the silica gel. Almost all the radicals generated by irradiation were initially in the bulk of the silica gel and migrated from the interior to the surface of the gel. When styrene monomer was adsorbed on the surface of the silica gel, the silica gel radicals interacted with the monomer and initiated polymerization and then generated polymer. The rate of migration of the silica gel radical was rather fast in the case of silica gel with a large specific surface area. Thus, the polymerization behavior of styrene adsorbed on silica gel greatly depended on the specific surface area of the gel.
Surface oxidation of cis–trans polybutadiene
Authors: Smith L. , Doyle C. , Gregonis D. E. , Andrade J. D.
Published: April 2003

Uncrosslinked cis–trans polybutadiene films were prepared on ultraclean glass microscope slides by uniform dipping. The samples were stored in different environments prior to evaluation of surface oxidation by dynamic contact angle using the Wilhelmy plate method and by X‐ray photoelectron spectroscopy (XPS). Storage conditions evaluated were: (1) laboratory air at 20°C and 30% relative humidity; (2) vacuum at 0.1 torr; (3) distilled water equilibrated with air; and (4) degassed distilled water. XPS and contact angle analysis indicate that samples exposed to air undergo significant surface oxidation within 8 h. Exposure of polybutadiene to air‐equilibrated water results in slower oxidation. Samples stored in degassed water demonstrated less surface oxidation. Vacuum‐stored samples demonstrated the least surface oxidation. Dynamic contact angle measurements demonstrated that receding contact angles are more sensitive to changes in surface oxidation than are advancing contact angles, as expected. Changes in surface wetting characteristics are readily observed after only 1 h in laboratory air, although XPS analysis does not show evidence of oxidation within 4 h of air storage.
Characterization of polymer‐coated optical fibers using a torsion pendulum
Authors: Manzione L. T. , Paek U. C. , Tu C. F. , Gillham J. K.
Published: April 2003

A freely oscillating torsion pendulum has been used to characterize the dynamic mechanical behavior of single polymer‐coated optical fibers. The dynamical mechanical spectra of the polymer coatings exhibit a glass transition temperature (Tg), a cryogenic glassy‐state relaxation (Tsec), and another cryogenic relaxation that is attributed to water present in the coating (TH2O). The shear modulus (G′) of the coating was computed from the shear moduli of the composite specimen and the core, assuming that the coating and core deform through the same angle on oscillation. The glassy‐state modulus was the same for both thin and thick coatings, although the intensity of the damping peaks, as measured by the logarithmic decrement, increased with coating thickness. Comparison of the dynamic mechanical behavior of a coated optical fiber and of a free film cast from the same reactive components shows that the polymer itself can absorb water at ambient conditions and display a mechanical relaxation at cryogenic temperatures. The T., H2O and Tsec relaxations are coupled with respect to their intensities. Latent chemical reactivity was found in one coating above its maximum temperature of cure. In this, the temperature of cure determines the glass transition temperature.
Mechanisms of formation of volatile aromatic pyrolyzates from poly(vinyl chloride)
Authors: Lattimer Robert P. , Kroenke William J.
Published: April 2003

The formation of volatile aromatic pyrolyzates in poly(vinyl chloride) has been studied by pyrolysis–gas chromatography–mass spectroscopy. Results from isotopic labeling experiments with perdeutero‐PVC suggest that the aromatic pyrolyzates can be divided into three general classes with respect to their formation mechanisms: (1) intramolecular—benzene and naphthalene are formed almost exclusively via intramolecular cyclization reactions; (2) mixed intra/intermolecular—styrene and indene can be formed either intramolecularly or via transfer of one hydrogen atom between PVC chains; (3) intermolecular—toluene and methylnaphthalene can be formed via transfer of one or two hydrogen atoms between chains. The isotopic distributions observed in the labeling experiments can be reasonably well explained without involving crosslinking (intermolecular CC bond formation) reactions.
High‐temperature redox‐initiated emulsion polymerization of butadiene
Authors: Padwa Allen R. , Paster Mark D.
Published: April 2003

The kinetics of the ferric ethylenediaminetetraacetate (EDTA)–diisopropylbenzene hydroperoxide (DIBHP)‐sodium formaldehyde sulfoxylate (SFS) redox system were determined. The rate constant is a function of the ionic strength μ. A plot of log10 (rate constant), for the rate‐limiting second‐order iron—SFS reaction, vs.μ1/2 has a slope of 1.3 with a limiting rate constant of 295 ± 15 L. mol−1. min−1 at μ = 0. The slope of this plot decreases to essentially zero for μ > 0.06M. Incorporation of these results into the Smith‐Ewart model for emulsion polymerization correctly predicts the dependence of latex particle size on Fe and DIBHP concentration, but a much lower dependence on SFS concentration is observed.
Interaction of polymerization conditions, structural variables, and mechanical properties of rubber‐modified plastics produced from bulk polymerized styrene/poly(butadiene‐co‐styrene)
Authors: Mui Ernie Tak Cheung , Boateng Victor Berko , Fellers John F. , White James L.
Published: April 2003

Rubber‐modified polystyrenes were prepared by bulk polymerization with seven different butadiene–styrene copolymers of differing chemical microstructures. The products were structurally characterized through measurement of the swell ratio, percent insolubles, intrinsic viscosity of the soluble fraction, and transmission electron microscope photomicrographs. Increasing initiator concentration or raising polymerization temperature gives lower molecular weight, higher rubber crosslink density, and decreased grafting. Increasing rubber content generally leads to aggregation. Tensile stress–strain curves and Izod impact strengths were measured. High Izod impact strength and increased elongation to break are favored by increasing matrix molecular weight, rubber content, and extent of grafting.
Characterization of cotton–polystyrene graft copolymers
Authors: Thejappa N. , Pandey S. N.
Published: April 2003

Characterization of cotton–polystyrene graft copolymers prepared by ceric ion initiation is reported. Various techniques studied include moisture sorption, solubility in cupriethylenediamine (CED), infrared spectra, differential thermal analysis (DTA), electron micrographs and X‐ray diffractograms, which point to the existence of true grafting. The graft copolymers showed a slight fall in breaking load and improved resistance to wetting.
Utilization of waste cellulose. IV. Comparative study of the reactivity of different substrates in the enzymatic hydrolysis with trichoderma viride
Authors: David C. , Thirỳ P.
Published: April 2003

Different cellulosic substrates are compared. Cellulose II (grinded Cellophane®) was demonstrated to be a very reactive substrate without any other pretreatment. Indeed, Cellophane®, even coated one side with PVDC or nitrocellulose, can be hydrolyzed to a very high yield of glucose in a reasonable time. Suspensions with an initial high content of substrate can be used. Different pretreatment (ball milling, γ‐irradiation, and Fe2+/H2O2) were found to modify the reactivity of cellulose I. The pretreatments which result in the chemical transformation of the glucose units of the initial cellulosic substrate are shown to inhibit the enzymatic hydrolysis.
Graft copolymerization of methyl methacrylate (MMA) onto silk using potassium peroxydiphosphate–cysteine (PP–Cys) redox system
Authors: Mishra Munmaya K.
Published: April 2003

Poly(methyl methacrylate) has been grafted onto mulberry silk in an aqueous medium by using potassium peroxydiphosphate–cysteine (PP–Cys) redox initiator. Various effects upon grafting such as concentration of cysteine, concentration of peroxydiphosphate, concentration of monomer, concentration of sulfuric acid, and temperature were studied. At a low range of cysteine concentration (6.25 × 10−4 mol/L), the rate of polymerization Rp (%/s) is proportional to cysteine concentration and the exponent is calculated to be 0.8. The monomer exponent is calculated to be unity up to the concentration of 65.72 × 10−2 mol/L. From the Arrhenius plot of log Rp vs. 1/T (T = absolute temperature) the overall activation energy is computed to be 15.19 kcal/mol. A suitable kinetic path has been pictured and a rate expression has been derived.
The dissolution of cellulose in anhydrous chloral/aprotic solvents
Authors: El‐Kafrawy Adel , Turbak Albin F.
Published: April 2003

Two new approaches toward the chemical modification and rapid dissolution of cellulose pulp in aprotic solvents containing chloral are presented. In the first method, cellulose pulp is water activated and then solvent exchanged prior to the addition of chloral. In the second method, cellulose pulp is heated in refluxing solvent and then cooled to ambient temperature before the addition of chloral. The methods do not entail the use of catalysts but require the preactivation of the pulp prior to treatment with chloral. Clear solutions obtained by the water activation–solvent exchange method were cast into films, and after washing with water the product was soluble in a variety of organic solvents including acetone. IR and NMR (1H and 13C) analyses as well as chemical analyses led to the conclusion that a cellulose chloral hemiacetal with a DS of 2.2 is initially formed which then slowly decomposes upon standing at 23°C to a relatively stable hemiacetal of DS 0.4. Complete regeneration to cellulose results upon standing for an extended period or treatment with 1 N acetic acid at 80°C, 1 N HCl at 50°C, 0.5% NH4OH or 0.1 N NaOH at 23°C. When solutions, obtained by the hot solvent activation method, were coagulated in water at ambient temperature, regenerated cellulose was obtained. In both methods, little or no degradation of the regenerated cellulose resulted.
Photodegradable polymers: Poly(arylene keto amine)s
Authors: Huang Samuel J. , Byrne Catherine A.
Published: April 2003

Low‐molecular‐weight poly(arylene keto amines) were prepared from the polymerization of 4,4‐bis(chloroacetyl)diphenyl ether, 4, 4′‐bis(bromoacetyl) diphenyl ether, and 4,4′‐bis(2‐bromopropionyl) diphenyl ether with piperazine, 4, 4′‐trimethylenedipiperidine, and N, N′‐dimethyl‐1,3‐propanediamine. These film‐forming polymers and suitable monomeric model compounds were found to be degraded by photolysis. The poly(keto amines) resisted degradation by the fungi As‐pergillus niger and Aspergillus flavus.
Effect of pH on the rate of emulsion polymerization of styrene initiated by potassium persulfate
Authors: Rahman A. , Brown C. W.
Published: April 2003

The influence of pH on the emulsifier property (micellar molecular weight) of sodium dodecyl sulfate has been studied in conjunction with the effect of pH on the rate of emulsion polymerization of styrene initiated by potassium persulfate. The rate of polymerization was found to be pH dependent. The micellar weight of sodium dodecyl sulfate has been determined at various pH values. The miceller weight was found to increase with decrease in pH. On the basis of the result, a suggestion was made that the effect of pH on micellar molecular weight can account for the observed behavior of the rate of polymerization.