bluuebunny/crossref_metadata_2025 huggingface dataset:
A simple relation to estimate the maximum tensile modulus of drawn polymer fibers
Authors: Bondi A.
Published: April 2003

The partial unfolding of folded lamellae crystals is taken as point of departure for the development of a model to describe the elastic properties of cold‐drawn polymer filaments. The resulting relation sums the van der Waals tensile compliance and the spectroscopic tensile compliance of the polymer backbone chain in proportion to the length of folded and unfolded crystal lamellae, respectively, in the drawn filament. Many reported tensile moduli of drawn filaments of semicrystalline polymers are substantially below the predicted value. However, specially careful drawing experiments are rewarded with tensile moduli which closely approach the magnitude predicted by the relation presented here.
Method for structural characterization of high polymeric networks by an osmotic pressure technique
Authors: Seeley R. D. , Rand P. B.
Published: April 2003

An apparatus was designed to measure the osmotic pressure of solvent–polymer systems. The method is unique in that semirigid polymers may be incorporated as the solute component without specimen fissures occurring from excessive solvent dilative action. The advantages of this technique are: high polymeric materials both elastomeric and plastic can be structurally characterized by the same technique; the calculated effective molecular weight of the polymer network will reflect a value consistent with the polymer's performance characteristics; and the method is only restricted to lyophilic polymer–solvent systems.
Crosslinked polyacrylamide gel as a dehydrating agent
Authors: Sherr Allan E. , Swift A. M.
Published: April 2003

The dried crosslinked gel prepared from acrylamide and N,N′‐methylenebisacrylamide has been shown to be an efficient drying agent. The effectiveness of the dried gel has been shown to be comparable with that of several inorganic dehydration agents.
FMIR infrared spectroscopy of coatings on fibers and metal plates
Authors: Hermann T. S.
Published: April 2003

The FMIR technique offers a new and improved means of identifying coatings on fibers, elucidating coating–substrate bonds, and determining the nature of absorption sites on substrates by infrared spectroscopy. This technique is based on the internal reflectance of radiation in the middle infrared region. The ability to obtain infrared spectra of surface materials without removing the materials from the fiber gives the FMIR technique a noteworthy advantage over transmission techniques.
Study on ozone treatment of water‐soluble polymers. I. Ozone degradation of polyethylene glycol in water
Authors: Suzuki Junzo
Published: April 2003

Polyethylene glycol (molecular weight 8000) was degraded by ozone in 1% aqueous solution of pH 12. Chemical oxygen demand of the solution decreased with increasing ozone consumed. Intrinsic viscosity of the solution lowered exponentially as a result of the ozonization. The number of breaks calculated from the viscosity indicated that two molecules of ozone were consumed for one cleavage of the polymer chain. The molecular weight distribution obtained by gel permeation chromatography was very broadened and molecular weight was lower as well, and the polymer chain was found to be cleaved randomly by ozone. The production of formic ester, ethylene glycol, diethylene glycol, triethylene glycol, and hydrogen peroxide was confirmed by IR, NMR, gas chromatography, and chemical analysis. These observations could be accounted for by electrophilic attack of ozone on the ether bond.
Structural changes in polyethylene films at small deformations
Authors: Lipatov Yu. S. , Moisya E. G. , Logvinenko P. N. , Mengeres G. Ya.
Published: April 2003

Structural changes in PE films at deformation 2–7% under constant load were studied by molecular probe method. It was shown that at these conditions some structural rearrangements take place which involves more than 20% of polymer volume, only 2–3% being transformed in the state of three‐dimensional ordering. The most part of ordering observed was connected with two‐dimensional ordering in the AC plane of molecular folding, involving tie chains near the crystallites. The effect of relaxation process during deformation on structural rearrangements in PE films was also investigated.
Kinetics of wet oxidation of nylon 66
Authors: Sundstrom D. W. , Luciano A. J. , Klei H. E.
Published: April 2003

The kinetics of the aqueous phase oxidation of nylon 66 was studied at temperatures up to 190°C. The nylon 66, in the form of a cylindrical disc, was attached to the shaft of a variable‐speed drive inside the reactor. With a rotating disc geometry, the chemical kinetics of the surface reaction can be separated from the mass transfer effects. By measuring the reaction rates at different temperatures, pressures, and disc rotational speeds, a kinetic rate expression was developed relating nylon degradation to dissolved oxygen concentration and temperature. The order of reaction with respect to dissolved oxygen concentration was 0.6, and the activation energy was 42 kcal/g‐mole.
Effect of molecular structure of phenolic resin on solder dip resistance and peel strength of printed circuit adhesives
Authors: Namiki Isamu
Published: April 2003

Phenolic resins were synthesized by using various kinds and amounts of catalyst and changing the mole ration of formaldehyde and phenol. The solder dip resistance and the peel strength were measured for two‐component printed circuit adhesives mixed with poly(vinyl acetal) resin, and the relation between these properties and the molecular structure of the phenolic resins were studied. Catalysts such as ammonia, amines having low boiling points, and alkaline earth metal oxide and hydroxides give resins with good properties. When the mole ratios of ammonia to phenol and formaldehyde to phenol are respectively 0.05–0.10 and 1.5, the resins obtained have good characteristics. The solder dip resistance is improved by aging the resin solution at moderate temperature.
Rheological properties of partially hydrolyzed ethylene–vinyl acetate copolymers
Authors: Jacovic Mihailo , Yamada Muneki , Macknight William J. , Porter Roger S.
Published: April 2003

Studies have been made of steady‐shear and dynamic viscosities for melts of two ethylene–vinyl acetate copolymers and their partially hydrolyzed derivatives using a Weissenberg rheogoniometer over the temperature range of 123–150°C with some tests at 160°C. The flow activation energy of all samples studied was essentially independent of shear stress. The introduction of hydroxyl groups in controlled concentrations, however, produced a complicated flow behavior. At low concentrations, there is a marked increase in Newtonian viscosity, flow activation energy, and shear dependence of viscosity. In contrast to previous reports, a further increase in all three functions was not observed with increasing vinyl alcohol concentration. Dynamic viscosities, in contrast, show monotonic increases with increasing hydroxyl group content, as do activation energies derived from the temperature dependence of the dynamic viscosity. These data may result from an increased chain cohesion due to hydrogen bonding of hydroxyl groups.
Analyse par résonance magnétique nucléaire des polycondensats urée–formol
Authors: Duclairoir Christian , Brial Jean‐Claude
Published: April 2003

The oligomer reaction products between urea and formaldehyde were preliminarily studied by 60‐MHz NMR spectroscopy. This analytical method was extended to urea–formaldehyde copolymers and provided means to attempt to determine their molecular stucture. Prior to NMR analysis, dilution water was removed by freeze drying in order to avoid degradation and advancement of the resin. Lithium chloride was found to enhance polycondensate solubility in deuterated dimethylsulfoxide and to improve resolution of the spectra by reducing overlapping of the signals. It was then possible to proceed to a qualitative and quantitative analysis of urea–formaldehyde copolymer structure. Structural differences appeared between one‐step synthesized resins and those involving a second urea addition; in the latter case, the percentage of unreacted urea was calculated. The shape of the unresolved broad signal assigned to the various methylene groups yielded further information on the resins. A particular shoulder on the methylene signal gives evidence for polyoxymethylene sequences occurring in polycondensates synthesized from concentrated aqueous formaldehyde solutions.
Photo‐induced graft copolymerization of methyl methacrylate on oxidized poly(vinyl alcohol) fiber
Authors: Ogiwara Yoshitaka , Yasunaga Toshio , Kubota Hitoshi
Published: April 2003

Photo‐induced graft copolymerization of methyl methacrylate on oxidized poly(vinyl alcohol) fiber was investigated. Oxidation of the fiber sample with sodium hypochlorite or periodic acid led the radical formation by photo‐irradiation to intensify markedly. ESR spectra of the irradiated oxidized sample proved that a considerable amount of triplet component radical was contained in it, whereas the unoxidized sample mostly indicated a singlet. The spectra found in the irradiated unoxidized sample was assigned to two radicals, I and II, and for the oxidized sample, to III and IV. The spectrum for I must be a singlet, and a triplet for II, III, and IV. Among the last three, II was less stable toward heat. As the oxidized sample has a high activity for photoinitiation, the radicals of III and IV are presumed to be the sites of graft copolymerization:
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Polymer composites containing plasma‐treated mica. I. Flow and mechanical properties
Authors: Schreiber H. P. , Tewari Y. B. , Wertheimer M. R.
Published: April 2003

Suzorite mica has been surface modified by microwave plasma treatment in ethylene gas. The surface‐treated mica was used as a filler in polyethylene, polystyrene, and a mixture of these two polymers. Significant changes in rheological behavior ensue. These indicate that adhesion between polyethylene and irradiated mica is superior to that of interfaces using unirradiated mica. In contrast, ethylene irradiation reduces the ability of filled polystyrene compounds to store elastic energy in melt flow, an effect consistent with impaired adhesion at interfaces involving these components. An intermediate situation exists in the case of the two‐polymer blend. The tensile properties of these systems also reflect surface treatment, reinforcement occurring in polyethylene‐containing compounds, while the tensile properties of polystyrene composites deteriorate. Plasma‐induced surface modifications of fillers to produce desired property changes in specified polymer matrixes are implied by the present work, but a fuller understanding of the chemistry of surface modification reactions is needed to substantiate these implications.
Preparation of macroreticular anion exchange membrane and its behavior relating to organic fouling
Authors: Kusumoto Koshi , Ihara Hirofumi , Mizutani Yukio
Published: April 2003

Base membranes were prepared by coating a monomer mixture consisting of styrene–divinylbenzene–polybutadiene–t‐amyl alcohol onto a polypropyrene cloth and subsequently by polymerizing the monomers. The resultant base membranes were chloromethylated and then quaternized. Thus, macroreticular anion exchange membranes were prepared and their properties were investigated. Furthermore, the organic fouling of the membranes was studied by using Na dodecylbenzenesulfonate as a foulant. The resistibility of the membranes was dependent on the balance between the porosity of the membranes and the foulant quantity.
Effect of the hydrophilic nature of growing radicals on the formation of particles in the preparation of soap‐free carboxylated polystyrene latexes
Authors: Sakota Kazuyuki , Okaya Takuji
Published: April 2003

Soap‐free carboxylated polystyrene latexes have been prepared by copolymerizing acrylic acid (AA) in a wide range of degree of neutralization using a slight amount of soap, and the particle formation process was investigated from the number and uniformity of particles. It was found that the degree of neutralization of AA as well as the amount of AA have a great effect on the formation of particles. On the basis of the calculation results of the composition of the growing radical formed in the aqueous phase at the initial stage of the polymerization, the results can reasonable be explained by a change in the hydrophilic nature of growing radicals formed in the aqueous phase at the initial stage of the polymerization, the results can reasonably be explained by a change in the hydrophilic nature of growing radicals which are formed in the aqueous phase and precipitate out to form particles. It was also established that the introduction of α‐methylstyrene or methyl methacrylate has a great effect on the formation of particles, which is consistent with the above‐described considerations.
Isocyanate resins from amide copolymers
Authors: Wright H. J. , Harwell K. E.
Published: April 2003

Useful isocyanate‐containing polymers may be made by reacting amide copolymers with a hypochlorite such as sodium hypochlorite. A highly branched carbon structure adjacent to the amide is required, otherwise the isocyanate is lost through reaction with components of the reaction mixture. The polymeric isocyanates react rapidly with monomeric and polyamines and at adequate rates with hydroxyl compounds. These polymers are very useful in paint films and other applications due to their ability to undergo crosslinking and chain extensions by reaction of the isocyanate groups.
Internal friction in polymer‐impregnated hardened cement paste
Authors: Whiting D. , Kline D. E.
Published: April 2003

Hardened cement paste (HCP) specimens were prepared with hydration times of 1, 3, 7, 28, and 180 days. Specimens were oven dried and subsequently impregnated with methyl methacrylate, tert‐butylstyrene, polyethylene glycol, and an epoxy resin system via a vacuum–pressure technique. Internal friction (Q−1) of in situ polymerized specimens was measured over the temperature range from 100° to 500°K. Results indicate that the internal friction spectra of polymer‐impregnated specimens closely parallels the internal friction spectra of the bulk polymers used for impregnation. Magnitudes of the internal friction peaks in the impregnated specimens were found to be less than that expected on the basis of volume fraction of polymer present. These results are attributed to hindered motion at the cement/polymer interface.
Structure of decrystallized cotton in fabrics prepared by alkali and acrylonitrile treatments
Authors: Hirai Asako , Tsuji Waichiro , Kitamaru Ryozo , Hosono Masao
Published: April 2003

The crystalline structure of decrystallized cotton, prepared by partial cyanoethylation with the use of sodium hydroxide aqueous solution and acrylonitrile, was examined by x‐ray and IR data, in connection with such fabric properties as moisture regain. It was found that the moisture regain of the cotton fabric first increased, passed through a maximum at about 6 mole‐% of cyanoethylation, and then slightly decreased with increasing degree of cyanoethylation. The increase of moisture regain in the region of the lower degree of cyanoethylation was well related to the decrease in the crystallinity of cotton. The x‐ray diffraction studies revealed that the distension and disorder of the unit cell occurred primarily in the direction perpendicular to the (101) crystal plane as cyanoethylation proceeded.
Gel formation in polymers undergoing radiation‐induced crosslinking and scission
Authors: Handlos V. N. , Singer K. A.
Published: April 2003

A study was made of the solubility of irradiated polyethylene. The experimental data were treated according to the Saito‐Inokuti theory for gel formation in polymers exposed to ionizing radiation. Among other things, this theory is based upon the molecular weight distribution of the unirradiated polymer; in the present work, the actual distributions were determined by high‐temperature gel permeation chromatography and corrected for long‐chain branching. Under these circumstances, good agreement between theory and experimental data was obtained, which allowed the determination of the radiation yield of main‐chain scission and crosslinking.
Water‐soluble polymers as retention aids in a model papermaking system. III. Modified polyacrylamides
Authors: Howard G. J. , Hudson F. Lyth , West Jeremy
Published: April 2003

The pigment retention efficiency, in a model papermaking system, of anionically and cationically modified polyacrylamides was compared to that of the unmodified homopolymer. The anionic polyacrylamide is a much less efficient retention aid, especially at high pH's; the nonionic and cationic polymers perform similarly and without any marked pH dependence. However, it is the nonionic and anionic polyacrylamides which are similarly poor at fiber flocculation, at pH's between 4.5 and 7.5, whereas the cationic polymer is a good fiber flocculant. All three polymers stabilize pigment suspensions. The anionic polymer is not effective in heteroflocculation of mixed dispersions of fibers and pigment, whereas both the nonionic and cationic are good flocculants, the latter being less susceptible to overdosing. Equilibrium adsorption isotherms were determined; the cationic polymers is, unlike the other modified polyacrylamide, very well adsorbed by cellulose fibers. Onto titanium dioxide, polymers adsorbed in the order anionic < nonionic < cationic. A further differentiation of the cationic polymer is that it gives high pigment retention in sheet formation without markedly increasing the resistance to fluid flow through the forming sheet. Although a process of heteroflocculation is postulated for both nonionic and cationic polymers, in the former case it is thought that the primary adsorption is onto titanium dioxide, whereas with the latter it is onto cellulose.
The kinetics of the trimethoxyboroxine‐induced thermal polymerization of phenyl glycidyl ether
Authors: Lopata Eugene S. , Riccitiello Salvatore R.
Published: April 2003

The kinetics of the bulk thermal polymerization of phenyl glycidyl ether induced by trimethoxyboroxine were investigated. Infrared absorption spectroscopy and gel permeation chromatography were used to follow the course of polymerization, while proton and boron‐11 NMR spectroscopy were used to support the kinetic model developed. The postulated mechanism involves a fast‐initiated, nonstationary cationic polymerization with five elementary steps, including spontaneous and monomer transfer as well as a termination reaction. The trimethoxyboroxine was found to be incorporated into the structure of the cured polymer. The polymerization was followed at several temperatures and with several ratios of initial concentrations of trimethoxyboroxine to phenyl glycidyl ether.
Transitions in phenolic polymer
Authors: Warfield R. W. , Lee G. F.
Published: April 2003

The solid‐state properties of a highly crosslinked amorphous resole‐type phenolic polymer have been studied by compressibility and torsional braid analysis measurements. Three secondary transitions were found over the temperature range of 123° to 623° K the largest of which occurs at about 393°K. These results confirm previously made electrical resistivity and specific heat measurements. These transitions are discussed in relation to the structure of this polymer.
Low‐frequency thermomechanical spectrometry of polymeric materials: Tactic poly(methyl methacrylates)
Authors: Gillham J. K. , Stadnicki S. J. , Hazony Y.
Published: April 2003

A computerized and automated torsional pendulum has been used to characterize amorphous poly(methyl methacrylates) at about 1 Hz in the temperature sequence 473° → 93° → 473°K. The effects of thermal prehistory, temperature cycling, water content, and tacticity are demonstrated. In particular, a comparison of the out‐of‐phase shear modulus (G″) versus temperature for “syndiotactic,” “atactic,” and “isotactic” polymer specimens shows that the intensity of the glassy‐state β loss peak decreases with increasing isotactic content while the temperature of its location remains the same. Extrapolation suggests that completely isotactic polymer would not display a β loss peak. The shape and location of the G″ data at low temperatures indicate that the basic mechanism of the β process is the same for the three polymer samples and support the validity of the extrapolation. The effect of tacticity is reflected also in the glass transition region; the isotactic sample has its Tg about 65°C lower with greater intensity than the syndiotactic polymer.
Peroxide crosslinking of ethylene–vinyl acetate copolymer
Authors: Narkis M. , Miltz J.
Published: April 2003

The work reported here concerns the peroxide crosslinking of ethylene–vinyl acetate rubber. Calculated values for scission‐to‐crosslinking ratios are higher for EVA than for low‐density polyethylene. In the temperature range from 150 to 200°C at a constant peroxide content, a rise in temperature results in a decrease in the obtained gel content. Some tensile and modulus–temperature results on crosslinked EVA samples are also reported on.
Iodine‐initiated, solid‐state copolymerization of tetraoxane with 1,3‐dioxolane in the presence of methylal. IV. Fractional dissolution of copolymer
Authors: Ishigaki Isao , Morishita Norio , Morita Yosuke , Ito Akihiko
Published: April 2003

A fractional dissolution on the oxymethylene copolymer obtained by the iodine‐initiated, solid‐state copolymerization of the tetraoxane–1,3‐dioxolane‐methylal system has been carried out using a mixed solvent which consists of tetrachloroethane, phenol, and cyclohexanol. On the fractional dissolution, the oxymethylene copolymer was divided mainly into two parts: one was the copolymer containing a larger amount of ethylene oxide unit in its main chain and having lower molecular weight; the other was copolymer containing a smaller amount of ethylene oxide unit and having a higher molecular weight. It was reasonably concluded that in this copolymerization system, the reaction proceeds from the surface to the center of the tetraoxane crystal to give a divided copolymer due to the heterogeneous properties such as copolymer composition and molecular weight.
Permeation properties of glycol chitosan–mucopolysaccharide complex membranes
Authors: Nakajima Akio , Shinoda Katsuro
Published: April 2003

The permeation properties of glycol chitosan–chondroitin sulfate C and glycol chitosan–heparin complex membranes have been studied. Discussion is devoted primarily to the desalination properties in reverse osmosis. Salt rejection and flux were dependent both on the composition of the membranes and the pH of the feed solutions. The results indicate that these complexes behave like polyampholytes. Minimum salt rejection occurs around the isoelectric point. Another characteristic of these membranes is a large pressure dependence of the salt rejection. This could be interpreted by assuming the compaction of these highly swollen membranes at high pressure.
Effect of water on permeation, diffusion, and solution of gases in cellophane
Authors: Kamiya Yoshinori , Takahashi Fumio
Published: April 2003

The laminate method for studying the permeability and diffusivity of moistened cellophane to gases is described and the humidity dependence of the transport parameters for H2, He, and Ne is presented. In the relative humidity region of about 0% to 60%, a small increase in the permeability was observed, which is caused by a comparatively small increase in the diffusivity owing to the plasticizing effect of sorbed water and a decrease in the solubility. On the other hand, an extremely large increase in the permeability observed in the relative humidity region above 60% is mainly based on the diffusion coefficient of gas enhanced by the swelling effect of sorbed water. The presence of a minimum in the solubility–relative humidity curves has been confirmed and is discussed.
Grafting of nylon 66 with methyl methacrylate using dimethylaniline–benzyl chloride–acetic acid initiating system
Authors: Hebeish A. , El‐Rafie M. H. , Khalil M. I. , Bendak A.
Published: April 2003

Grafting of nylon 66 with methyl methacrylate (MMA) under the initiating influence of dimethylaniline (DMA)–benzyl chloride (BC)–acetic acid (AC) mixture was studied to discover optimal conditions for grafting. Results of this investigation showed that a mixture of water/ethanol at a ratio of 90:10 constitutes the most favorable medium for the grafting reaction. Optimal grafting occurred when a concentration of 0.16 mole/l. DMA plus 0.17 mole/l. BC plus 0.2 mole/l. AC was used. Using lower or higher concentrations of this initiator led to lower grafting. On the other hand, increasing MMA concentration brings about a significant increase in the graft yield. The same holds true for reaction time and temperature, though an induction period was observed at a lower temperature (65°C) and when lower monomer concentration (2%) was used.
Flex‐resistant permeable PVC films
Authors: Otterstedt Jan‐Erik A.
Published: April 2003

Microporous poly(vinyl chloride) films with flex resistance in excess of 400,000 flexes at 20°C and 65% R.H. and in excess of 30,000 flexes at −;15°C, and water vapor permeability in excess of 250 g/m2 24 hr have been prepared from controlled expansion and curing of plastisols, which contain a poly(vinyl chloride) (PVC) resin with a K value of 75 or more and a plasticizer with a solubilizing power not greater than that of dioctyl phthalate. Controlled curing produces uniformity in the morphology of the cell walls while maintaining sufficiently high melt viscosity to retain the open structure of the porous material.
Rupture mechanisms of elastomer–metal adhesive systems
Authors: Schultz J. , Westbrook N. J.
Published: April 2003

This paper studies the influence of adverse conditions of stress and environment on a conventional industrial two‐coat adhesive system for bonding filled elastomers to steel. Several test methods were used in order to produce rupture at the elastomer/adhesive interface, but even the most stringent stress distributions produced rupture in the elastomer under relatively rapid constant strain rate testing conditions. However, under fixed strains termed“static fatigue” below immediate rupture conditions, fracture occurred cohesively in the adhesive. This fracture originated in the elastomeric phase of the adhesive. Comparison of elastomer and adhesive creep curves show that the locus of failure depends only upon the ultimate properties of the phase in which fracture occurs. This becomes more complicated for propagation of the fracture because of the influence of rheological, thermodynamic, and morphologic aspects of the other constituents of the assembly. A third type of rupture, produced at the metal surface, was observed by testing under corrosive conditions such as saline solution. Throughout the study, original observations are confirmed for systems using different elastomers, adhesives, or metal surface coatings.
Dynamic mechanical and thermal properties of fire‐retardant high‐impact polystyrene
Authors: Chang Eng Pi , Kirsten Rudy , Slagowski Eugene L.
Published: April 2003

The interaction of a series of fire‐retardant additives with high‐impact polystyrene (HIPS) has been inferred from their dynamic mechanical and thermal properties. High‐melting additives phase separate and act as inert filler in both the rubber and polystyrene phases, while low‐melting additives raise the Tg of the rubber phase and plasticize the polystyrene phase. Antimony oxide antiplasticizes the grafted rubber phase but acts as inert filler in the polystyrene phase. The impact strength of these fire‐retardant HIPS's shows good correlation with the integrated loss tangent of the rubber Tg peak indicative of large energy dissipation in the rubbery region during impact causing the matrix to craze or flow. It is also suggested that additives which are compatible with, and localized in, the polystyrene phase help retain the impact strength of HIPS.
Studies on the photo‐oxidation mechanism of polymers. VI. The role of commercial thermostabilizers in the photostability of poly(vinyl chloride)
Authors: Rabek J. F. , Canbäck G. , Rånby B.
Published: April 2003

This paper presents a study on the photolysis of PVC in the presence of different types of tin stabilizers. Using physicochemical methods such as ESR spectroscopy, conductivity titration, gel permeation chromatography, and absorption spectroscopy, the mechanism of PVC photolysis has been investigated. ESR spectroscopy shows that during UV irradiation of tin stabilizers, different types of free radicals depending on the chemical structure of the examined compounds are formed. It has been found that the presence of tin stabilizers does not significantly influence the photo‐oxidation and degradation of PVC but influences the crosslinking processes. The authors propose an interpretation of the free‐radical formation during UV photolysis of tin stabilizers and of the crosslinking acceleration mechanism.
Semicontinuous emulsion copolymerization of acrylonitrile, butyl acrylate, and styrene
Authors: Šňupárek Jaromír , Krška František
Published: April 2003

Semicontinuous emulsion copolymerization of acrylonitrile (M1), butyl acrylate (M2), and styrene (M3) was investigated. The copolymerization proceeded under the conditions used with a high degree of conversion, whereby a stationary state characterized by a constant monomer mixture composition and a constant composition of the arising copolymer was achieved. From the analytically estimated free monomers and arising copolymer compositions, the reactivity ratios for the pair AN/BA r12 = 0.71, r21 = 1.17 and for the pair AN/Sty r13 = 0.06, r31 = 0.28 were calculated. The applicability of the reactivity ratios found was verified also for the ternary system acrylonitrile/butyl acrylate/styrene.
Randomly branched styrene/divinylbenzene copolymers. II. Solution properties and structure
Authors: Ambler M. R. , McIntyre D.
Published: April 2003

The [η] of randomly branched PSty/DVB continually decreases from linear polystyrene with increasing conversion. On the other hand, the relation of the 〈S2〉 to M of both low and high conversion series is equivalent, although the actual size is smaller than that of linear polystyrene of the same M. This fact, in conjunction with the previously published reactivity ratios, allows the following interpretation of the mechanism of copolymerization: namely, that branched molecules are formed in which the center core is higher in DVB content than is the periphery. Only about 1/7 of the available DVB units act as effective tetrafunctional branch points. An analysis of GPC data correlated with light scattering and viscosity dimensions allows the g value to be determined in the lightly and highly branched fractions. The viscosity ration is related to gx, where x is 0.65 for low conversion fractions (A series) and becomes 1.41 for high conversion fractions (B series). This change in exponent is postulated to arise from an increase in branching density as conversion increases. The ratio of the hydrodynamic radius to the radius of gyration is higher for branched than for linear polymers. The theta temperature (θ) in cyclohexane for randomly branched polystyrene compared to linear polystyrene is always higher and can be as much as 2° higher.
Thermal analysis of thermosetting phenolic compounds for injection molding
Authors: Siegmann A. , Narkis M.
Published: April 2003

The differential scanning calorimetry technique has been applied to investigate the curing of injection molding phenolic compounds. The data obtained include degree of cure, rate of curing, and heats and temperatures of curing as function of various heating rates, rate constants, energy of activation, and glass transition temperature. The curing temperature and heating rate were found to affect both the curing reaction kinetics and the final structure of the crosslinked network. The glass transition temperature changes continously with the extent of curing, approaching the cure temperature.
Preparation of crosslinked poly(styrene–g–N‐carboxyalkylated ethylenimine) as chelating resin
Authors: Saegusa Takeo , Kobayashi Shiro , Yamada Akira
Published: April 2003

Carboxymethyl and ethyl groups were introduced into crosslinked poly(styrene–g–ethylenimine) (PSt–g–EI), consisting of a crosslinked polystyrene backbone with linear polyethylenimine branches, by the reaction of PSt–g–EI with monochloroacetic acid and β‐chloropropionic acid. Carboxyethylation was also performed by reaction of the PSt–g–EI with acrylic acid. The extent of the reaction was determined by the change in the nitrogen content of the resin. The adsorption of metal ions such as Cu2+, Cd2+, Hg2+, Ni2+, and Ca2+ by carboxyalkylated PSt–g–EI was examined. With the introduction of carboxyalkyl groups, the adsorption capacity for metal ions (per gram of resin) decreased, whereas the affinity of the resin for these ions increased.
Posttreatment effects on pore size distribution of loeb‐sourirajan‐type modified cellulose acetate ultrathin membranes
Authors: Ohya Haruhiko , Konuma Hozumi , Negishi Yoichi
Published: April 2003

The nitrogen gas adsorption isotherms at −195°C on modified cellulose acetate ultrathin membranes were measured, and the surface area of the pores was determined by the method employed by Cranston and Inkley. A relationship between reverse osmosis characteristics and the mean pore radius was correlated, and it was observed that any method (such as longer evaporation period, heat treatment, or reduction of swelling agent) reducing the mean pore radius to below 20–22 Å improves membrane characteristics of reverse osmosis separation significantly.
The ultimate polymer application: Resin‐bonded cellulose separators for lead–acid batteries
Authors: Dafler James R.
Published: April 2003

Because it represents a polymer system routinely used in a highly corrosive environment, the resin‐bonded cellulose separator is a paradigm of bad polymer application that succeeds. It succeeds because of the remarkable properties of cellulose itself, and through the formation of a highly modified structure that serves to protect both the resin and the cellulose in a reactive environment known to completely degrade both. X‐ray diffraction analysis was used to determine the quality of retained cellulose in lead–acid battery separators made by impregnating thick cellulose matrixes with phenolic resins. The hydrolytic weight loss of separators stored in battery acid at 52°C was also measured and related to x‐ray diffraction measurements of intensive degree of crystallinity and “qualitative perfection.” The x‐ray diffraction analyses and hydrolysis measurements are consistent with the formation of a copolymer between the cellulose and the impregnating resin. Treated and rewetted α‐cellulose displays a capability for reorganization, indicated by increases in intensive crystallinity and qualitative perfection that are absent in the resin‐bonded cellulose separator matrix. Rewetting of the separator matrix actually decreased the “qualitative perfection” of the cellulose present. X‐ray diffraction measurements indicate that extensive crystallinity of acid‐treated separators increases, due probably to the higher reactivity of the “so‐called” amorphous fraction of the cellulose present. The degree of crystallinity, an intensive measure, does not change significantly during acid treatment, but the “qualitative perfection” of the cellulose decreases with time of hydrolysis and increases in acid strength.
Casting of organic glass by radiation‐induced polymerization of glass‐forming monomers at low temperature. I. Optical strain of thermal stream type
Authors: Yoshi Fumio , Okubo Hiroshi , Kaetsu Isao
Published: April 2003

It was found previously that cast articles of transparent polymer without optical strain could be obtained efficiently in a very short time by radiation‐induced polymerization of glass‐forming monomers at low temperature. Two types of optical strain were observed in casting of these monomers: thermal stream type and remaining (inner) stress type strain. The mechanism of thermal stream‐type strain formation was investigated by following the heat and temperature change during cast polymerization in this report. It was found that the temperature difference between the upper and lower part of the sample was large and the temperature was much higher in the upper part than in the lower part under conditions of strain formation. Increase of heat removal from the sample surface decreased the temperature difference in the vertical direction and reduced the strain formation. It could be deduced that stream‐type strain formed as a result of thermal stream and it was retarded in radiation casting of glass‐forming monomers owing to high viscosity and low temperature.
Gas permeability and side chain structure of poly(γ‐benzyl L‐glutamate)
Authors: Oohachi Y. , Hamano H. , Yoshida T. , Tsujita Y. , Takizawa A.
Published: April 2003

Three structural modifications of poly(γ‐benzyl L‐glutamate) (PBLG), forms A, B, and C, were prepared by varying the casting solvents and casting temperature. From x‐ray analysis, infrared absorption spectroscopy, differential scanning calorimetry, and viscoelastic measurements, it is concluded that form A of PBLG is characterized by intramolecular stacking between the benzene rings in the side chain, form B exhibits intermolecular stacking, and form C has no stacking. The transition which corresponds to the breakdown of stacking of form A at 135°C is irreversible, while that of form B at 110°C is reversible. The degree of stacking is larger for form A than for form B. These structural features of the side chain region reflect the permeation and sorption behavior of carbon dioxide. Breakdown of stacking between benzene rings causes an abrupt increase in permeability in both form A and form B, and the permeation behavior for form A is not reversible, as is suggested from the irreversibility of the transition. The larger the degree of stacking, the lower is the amount of sorption. Although stacking is considered to affect the sorption site (solubility) and molecular motion, its influence on solubility is more evident in the temperature range up to about 50°C.
Pyrolysis–molecular weight chromatography–vapor‐phase infrared spectrophotometry: An on‐line system for analysis of polymers. IV. Influence of cis/trans ratio on the thermal degradation of 1,4‐polybutadienes
Authors: Tamura Saburo , Gillham John K.
Published: April 2003

The influence of the cis/trans ratio of 1,4‐polybutadienes on the volatile products formed during temperature‐programmed thermal degradation to 15% weight loss has been investigated using a mass chromatograph (a gas chromatograph which directly provides mass numbers of resolved components of a mixture) and an “on the fly” vapor‐phase infrared spectrophotometer. In order of amounts, major volatile products were 4‐vinyl‐1‐cyclohexene (dimer), 1,3‐butadiene (monomer), cyclopentene, and 1,3‐cyclohexadiene. With increasing trans content, the relative quantities of 4‐vinyl‐1‐cyclohexene decreased strongly, cyclopentene increased strongly, 1,3‐butadiene decreased moderately, and 1,3‐cyclohexadiene increased moderately. For a high‐trans polybutadiene, increasing the heating rate produced relatively more monomer and dimer but less cyclopentene. Mass chromatograms from 1,4‐polybutadienes which had been heated to 15% weight loss in their prehistory were similar to those obtained from 1,2‐polybutadiene, indicating that 1,4‐polybutadiene undergoes isomerization prior to degradation. Mechanisms for the formation of the main volatile products of decomposition are discussed.
Properties of fabricated poly‐p‐phenylene
Authors: Gale David M.
Published: April 2003

Mechanical properties of fabricated poly‐p‐phenylene (PB) parts are compared to those of commerical polyimide. PB showed excellent retention of strength and stiffness at high temperature. Results of environmental exposure and properties of some PB composites are included. In general, PB parts have properties between those of commercial polyimide and carbon graphite.
Graft frequency of graft copolymers by chain transfer of growing polymer radicals to trunk polymers containing nitro groups
Authors: Nakamura Shigeo , Yamada Masaei , Matsuzaki Kei
Published: April 2003

The relationship between the chain transfer constant, extent of monomer conversion, and number of branches was derived for the graft copolymerization through chain transfer of growing polymer radicals to the pendent aromatic nitro groups on the trunk polymer. The equation derived enables us to predict the number of branches for a given monomer trunk polymer. The relationship obtained is compared with the experimental data previously reported for the graft copolymerization of styrene onto poly(vinyl p‐nitrobenzoate). The value of α′, the ratio of nitro groups with branches to those which are attacked by polystyrene radicals, is less than unity except for the graft copolymers obtained with high initiator concentrations and at early stages of the reaction. This lowering of α′ is attributed to the steric hindrance of branches already formed on the trunk polymer which prevents the attack of polystyrene radicals on the nitro groups and side reactions, such as reaction of the nitroso groups formed as an intermediate with styrene.
Studies in dyeing. II. Effect of crystal modification of disperse dyes on polyester dyeing at 130°C
Authors: Shenai V. A. , Parekh R. B.
Published: April 2003

Four commercial disperse dyes were purified and their different crystal forms were prepared by crystallizing from different solvents or precipitating from their solutions in glacial acetic acid by dilution with water. These forms were found to have different melting points. They were dyed on polyester fibers at 130°C to fiber saturation values by changing the dyebath every 15 min. The effect of pretreatment of the dyes in an aqueous environment at different temperatures (60°, 100°, and 130°C) for 15–60 min in the presence and absence of a dispersing agent on the dye uptake values was also studied. Such treatments are shown to reduce the dye uptake. The implication of these treatments in practical dyeing are pointed out.
Some orientation studies on blown polyethylene films by infrared spectroscopy
Authors: McRae M. A. , Maddams W. F.
Published: April 2003

Infrared dichroic measurements have been made on a number of blown polyethylene films for which x‐ray diffraction pole figure studies are reported in the three preceding papers; they complement them in some respects, and lead to several conclusions. Gauche chain conformations in loose chain folds in amorphous regions, characterized by bands at 1303, 1352, and 1368 cm‐1, show appreciable orientation in films with high‐stress orientation but very little with low‐stress orientation. Conversely, extended tie chains in amorphous regions, assessed by the band at 1080 cm‐1, are appreciably orientated with the more normal type of low‐stress film but not with high‐stress films. It is therefore possible, rapidly and inexpensively, to distinguish between the two types of orientation. The method for studying the orientation of extended tie chains is capable of further development. There is probably an empirical correlation between the dichroic ratios at 720 and 730 cm‐1 and the tear strengths and balances of the films with low‐stress orientation.
Biegeverhalten von kernverbund‐systemen
Authors: Lang Dr.‐Ing. G.
Published: April 2003

The data for the calculation of tensions and bendings of sandwich structures show that in case of bending loads, which are not free from transverse forces, shearing stress occurs in the core, and this stress influences the bending properties of polyethylene compound cores provided with aluminum facings. This influence is due to the viscoelastic properties of the polymers participating in the compound, dependent on the temperature and the load duration. Additives mixed into the core material produce, besides increased rigidity of the core itself, a more favorable bending behavior provided it has been possible at the same time to improve the firmness of the adhesive effect between the plates and the core by means of the additive. In this case the influence of the production conditions must be taken into consideration.
Curing behavior of two‐step phenolics by solvent extraction
Authors: Tonogai S. , Sakaguchi Y. , Seto S.
Published: April 2003

In examining the degree of cure of the novolac—hexamine system, higher‐boiling polar solvents such as methylcellosolve and cyclohexanone were found to have better extraction power than that of acetone, even for resins with a relatively high degree of cure. Making use of the difference in their extraction power, the cured resins could be fractionated into four portions, i.e., acetone soluble, acetone insoluble but methylcellosolve soluble, methylcellosolve insoluble but cyclohexanone soluble, and cyclohexanone insoluble. The formation and subsequent diminution of the soluble intermediates and the increase of insoluble crosslinked resins in the curing process were shown clearly by plotting the amount of each fraction against curing time at various temperatures. Further, the same extraction procedure was applied to the resins cured under reduced pressure. The curing reaction was markedly delayed in the latter case. Based on the remarkable difference in the curing behavior under pressure, a curing mechanism has been proposed in which the moisture contained may acelerate the decomposition of hexamine, thus enhancing the reactivity of the resin system.
Solubility criteria for a thermally stable polymer determined by gas–solid chromatography
Authors: Dinçer S. , Bonner D. C.
Published: April 2003

The Gibbs energy of adsorption, the Flory‐Huggins interaction parameter χ, and a specific interaction parameter A, based on hydrogen‐bonding and charge‐transfer complexing properties of solvents, are obtained by gas—solid chromatography for a type of polyquinoxaline denoted as PQF. Interactions between 40 organic solvents and PQF have been determined at 176.35° and 200.85°C. PQF is an aromatic, heterocyclic polymer which is at least partially soluble in several organic solvents. The parameters χ and Λ and the solubility parameters of solvents are proposed to be the determining factors for miscibility of a PQF—solvent pair.
Photostabilization of commercial polypropylene by a hindered amine stabilizer
Authors: Allen N. S. , McKellar J. F.
Published: April 2003

The photostabilization of commercial polypropylene by a hindered amine stabilizer is examined by luminescence and ESR spectroscopy. The presence of the amine stabilizer inhibits the photolysis of the α,β unsaturated carbonyl impurity groups present in the polymer. Examination by ESR, of the stabilized polymer before and after irradiation shows the development of a highly stabilized free radical indicating that the stabilizer can act as an ultraviolet stable antioxidant. Possible mechanisms whereby the hindered amine inhibits the photolysis of the α,β unsaturated carbonyl groups are discussed.
Grafting vinyl monomers onto wool fibers. I. Graft copolymerization of methyl methacrylate onto wool using V5+–thiourea redox system
Authors: Nayak Padma L. , Lenka Subasini , Pati Nrusingh C.
Published: April 2003

The graft copolymerization of methyl methacrylate in wool fibers was investigated in aqueous solution using V5+—thiourea redox system. The rate of grafting was determined by varying monomer, thiourea, acidity of the medium, temperature, nature of wool, different acrylic monomers, and reaction medium. The graft yield increases significantly by increasing reaction time in the initial stages of the reaction but it does slow down on prolonging the duration of grafting. The effect of increasing monomer concentration brings about a significant enhancement in the graft yield. The graft yield increases with increasing thiourea concentration, but beyond 0.0075M, the percentage graft yield decreases. The graft yields are considerably influenced by chemical modification prior to grafting. Wool reduced with thioglycolic acid is more susceptible to grafting than untreated wool; the opposite effect is noted in the case of trinitrophenylated and esterified wools. A suitable kinetic scheme has been proposed and the rate equation has been evaluated.