bluuebunny/crossref_metadata_2025 huggingface dataset:
Graft copolymerization of lignosulfonate and styrene
Authors: Chen R. , Kokta B. V. , Valade J. L.
Published: April 2003

A study was made of the graft copolymerization of calcium lignosulfonate with styrene. Heterogenous copolymerization were carried out with methanol as swelling medium, using ferrous ion as catalyst, and ozone and/or hydrogen peroxide as initiator. When using peroxide alone as initiator, monomer conversion was low; after ozonization of lignosulfonates, monomer conversion increased considerably and the grafting efficiency, as well as degree of lignosulfonate grafted, was improved. At 55°C, a 10‐fold increase in conversion was observed for reactions with ozone‐pretreated lignosulfonates. The investigated factors that affected the graft copolymerization were: the amount of peroxide and ozone charged, the reaction temperature and the ratio of styrene/methanol.
Nonterminal unsaturated silane coupling agents for mineral‐filled ethylene–propylene rubber
Authors: Vondráček Petr , Čapka Martin , Schätz Miroslav
Published: April 2003

This paper describes the results of an experimental investigation concerning the effect of reactive organofunctional unsaturated silanes on mechanical properties of mineral‐filled ethylene–propylene elastomers. The tested group of the unsaturated silanes was prepared by hydrosilylation syntheses. The experimental silanes, 2,6‐octadienyltriethoxysilane, cis‐2‐butenyltriethoxysilane, 2‐(3‐cyclohexenylethyl)triethoxysilane, and 2‐(3‐cyclohexenylethyl)methyldiethoxysilane, led to a considerable improvement in mechanical and electrical properties of mineral‐filled vulcanizates based on peroxide‐cured ethylene–propylene elastomers. From the tested silanes, the 3‐cyclohexenylethylsilanes impart an improvement comparable with the action of vinyltris(2‐methoxyethoxy)silane, presently used as a standard coupling agent in mineral‐filled peroxide‐cured elastomers.
Irradiation of poly(vinyl chloride) with H2 plasma. I
Authors: Zahran A. H. , Nofal E. , Elsabee M. Z. , El‐Azmirly M. A.
Published: April 2003

A system has been designed to serve as a plasma source and has the advantage of producing plasma of known energy and controlled intensity. Poly(vinyl chloride) films were irradiated with hydrogen plasma for different intervals of time. The effect of irradiation time and storing on the extent of crosslinking was investigated. The viscosity of the soluble part decreased at the initial stage of irradiation, then increased. The crosslinking extent was observed by measuring the swelling ratio of the irradiated samples. Spectral analysis indicated the formation of carbonyl groups and polyene structure in the irradiated PVC. The mechanisms of dehydrochlorination and crosslinking are discussed.
Some surface properties of plasma polymers prepared from hexamethyldisilazane and diethylaminotrimethylsilane
Authors: Hirotsu Toshihiro
Published: April 2003

Plasma polymers from some silyl amines were produced by the radio frequency of 13.56 MHz, and the surface properties were investigated. The polymers were revealed to be as hydrophobic as a plasma polymer from tetramethylsilane, which does not contain nitrogen. The hydrophobicity became effective at around 50 Å thicknesses of these polymer layers deposited on micro‐slide glass. These polymers have gradually become comparatively hydrophilic with the aging. The change of wettability is probably due to the oxidation of these surface layers to form oxides and peroxides, which are more hydrophilic. The hydrophobic character of silyl amine plasma polymers could be explained by the lack of amines and/or amides in these polymers, as observed with ATR‐IR and ESCA spectra. These spectroscopic observations also suggest that nitrogen is a more fragile element in plasma than carbon or silicon in the silyl amines.
Functional silane‐modified calcium carbonate
Authors: Nakatsuka Takuo , Kawasaki Hitoshi , Itadani Katsuhiko , Yamashita Shinzo
Published: April 2003

In the course of graft polymerization of styrene on a calcium carbonate powder surface treated with a silance coupling agent such as γ‐methacryloxypropyltrimethoxysilane, gelation of the reaction mixture was observed just as on silane‐modified clay. Infrared spectroscopic and gel‐permeation chromatographic studies have revealed that the extracts of styrene monomer from the powder surfaces contained polymeric silane coupling agent, having crosslinking ability, besides monomeric silane coupling agent. The catalytic effect on the condensation of the silane coupling agent on the powder surface was found to be increased in following order: CaCO3 < P‐CaCO3 < clay, where P‐CaCO3 is a calcium carbonate modified with phosphoric acid. The order was parallel to the gelation tendency and to the acidity order (H0 ⩽ 6.8) on the surfaces. Direct evidence for bonding between the silane coupling agent and the phosphate moiety on calcium carbonate was not available; however, the silane‐modified P‐CaCO3 filler exhibited more reinforcing effects in peroxide‐cured ethylene–propylene–diene rubber (EPDM) and in sulfur‐cured styrene–butadiene rubber (SBR) than the silane‐modified calcium carbonate. These reinforcing effects are also discussed in relation to the molecular weight distribution of the silane coupling agent extracted.
Rheology and water swelling of carboxymethyl starch gels
Authors: Taylor N. W.
Published: April 2003

A series of gels differing in ionic content was prepared by derivatizing starch with varying amounts of carboxymethyl add‐on. Some derivatives were lightly crosslinked with epichlorohydrin to reduce soluble material and increase the amount of gel. The gel fraction of each batch was isolated, and viscosity η, shear modulus G, and swelling in water and salt solution were then determined. One gel suspension, examined in more detail, was demonstrated to behave as a closely packed gel thickening agent, thereby warranting use of the three reduced functions: reduced concentration cQ (c is weight concentration of polymer, Q is swelling capacity in excess fluid), η/cQ, and G/c1/3. At cQ greater than about 2, η/cQ, and G/c1/3 reach constant plateau values, as is typical of other examples of closely packed gel thickeners. In a comparison among the gel suspensions, plateau values of the reduced viscosity function were nearly proportional to the apparent crosslink density G/c1/3, in agreement with other closely packed gel thickeners, but were not affected by ionic content of dry polymer. The water swelling capacities of the different gels ranged from 47 to 150 g/g and were correlated with both ionic contents and apparent crosslink densities, but the effects of these variables were less than suggested by theory.
Statistical analysis of nitrogen‐containing vinyl copolymers: Radiation‐induced copolymerization of vinyl acetate and N‐vinyl‐2‐pyrrolidone
Authors: Peppas Nikolaos A. , Gehr Todd W. B.
Published: April 2003

Radiation‐induced copolymerization of vinyl acetate and N‐vinyl‐2‐pyrrolidone was carried out at 5°C using γ‐irradiation of 1450 rads/min. Copolymers prepared at conversions lower than 5% were analyzed by a saponification technique. Various linear and nonlinear statistical analysis techniques were used to determine the reactivity ratios of this system as r1 = 0.348 and r2 = 3.108. These data were examined and analyzed in relation to problems of elemental analysis involving nitrogen‐containing copolymers and to discrepancies in the reactivity ratios obtained by previous investigators. The presence of oxygen and a higher dose rate did not affect the copolymer composition within statistical error. Hydrolyzed copolymers prepared by this method have potential applications as biocompatible materials.
Synthesis of thermosetting polymers from the by‐products of coal conversion processes
Authors: Giori C. , Eisenberg W. , Yamauchi T. , Shelfo S. , Solomon I.
Published: April 2003

The use of coal conversion by‐products as raw materials in the synthesis of thermosetting polyesters has been investigated. Heavy tar residues were oxidized by gaseous oxygen in an alkaline medium, yielding a complex mixture of benzenecarboxylic acids and smaller amounts of aliphatic carboxylic acids. The mixture was polymerized by condensation with tetraethylene glycol “bottoms,” a by‐product of the synthesis of ethylene glycol. The resultant polyesters were cured by reacting them with epoxy resins in the presence of basic catalysts. Molded sheets and laminates were fabricated and tested. Tensile strength was found to increase with increasing curing time and with increasing concentration of epoxy crosslinking agent. Glass‐reinforced composites fabricated by the autoclave process showed an increase in flexural and shear strength with decreasing autoclave pressure.
On the thickness and spatial distribution of a fluoropolymer film deposited by solution dipping
Authors: Tompkins H. G. , Sharma S. P.
Published: April 2003

Poly‐1H,1H‐pentadecafuorooctyl methacrylate is a barrier compound used to prevent silicone oil from creeping to relay contacts. It is essentially a methyl methacrylate polymer with a fluorocarbon side chain substituted for one of the methyl hydrogens. It is applied by dipping the part into a solution, with Freon TF as the solvent and the fluorocarbon polymer as the solute. This work considers the spatial distribution of the resulting film of barrier compound when it is deposited in this manner. The specific variables considered are concentration and withdrawal velocity. The samples were withdrawn from the solution with velocity perpendicular to the surface, and we show that the macrosopic uniformity and thickness of the film is dependent on this velocity. There exists a critical velocity (dependent on concentration) above which the film is nonuniform and below which the film is macroscopically uniform. Below the critical velocity, the thickness varies with velocity with approximately a v2/3 dependence. The critical velocity is about 13 mm/sec for a concentration of 0.2%. For macroscopically uniform films, a microscopic nonunitormity exists with a coverage of about 1/4 for an average film thickness of 90 Å.
Graft copolymerization of vinyl monomers onto modified cottons. XII. Grafting of 1,1‐dihydroperfluoroheptyl acrylate onto cellulose carbamate using hydrogen peroxide as initiator
Authors: Hebeish A. , El Alfy E. A. , Waly A. , Abou‐Zeid N. Y.
Published: April 2003

Cellulose carbamate having 1.4% N was grafted with 1,1‐dihydroperfluoroheptyl acrylate (DHPFHA) using H2O2 as initiator under a variety of conditions. The technique used involved padding the fabric in H2O2 solution at room temperature followed by impregnating it in an aqueous emulsion of DHPFHA. The graft yield, expressed as fluorine percent, was found to depend upon monomer and initiator concentration, temperature, and reaction time and pH of the polymerization medium as well as upon the carbamate content of the modified cotton. Increasing the monomer concentration up to 5% caused a considerable enhancement in grafting. The same holds true for initiator concentration up to a certain limit after which the grafting decreases. Raising the reaction temperature up to 100°C was accompanied by an increment in the magnitude of grafting reaction. The latter was characterized by an initial fast rate followed by a slower rate. Slightly acidic media (pH 5–6) proved to be the best for performing grafting. The graft yields were quite poor when grafting was carried out in acidic (pH 2–4) or alkaline (pH 8–12) media. The presence of a relatively smaller amount of carbamate groups in the cellulose molecules decreases its susceptibility to grafting. The opposite holds true for larger amounts. Incorporation of FeSO4 at low concentration in the monomer emulsion had no effect on the graft yield. However, the latter decreases at higher FeSO4 concentration. Grafted cellulose carbamate having ca. 15% fluorine showed very good oil and water repellency. The grafted product retained ca. 85% of the strength of cellulose carbamate.
Grafting onto wool. VII. Ceric ion‐initiated graft copolymerization of vinyl monomers. Comparison of monomer reactivities
Authors: Misra B. N. , Mehta Inderjeet K. , Dogra Ramesh
Published: April 2003

In an attempt to compare relative reactivities of vinyl monomers toward grafting, methyl methacrylate (MMA) and acrylic acid (AAc) were grafted separately to Himachali wool in aqueous medium by using ceric ammonium nitrate (CAN) as redox initiator. Nitric acid was found to catalyze the reaction. Percent grafting was determined as a function of concentration of nitric acid, concentration of CAN, concentration of monomer, time, and temperature. Optimum conditions for maximum grafting were evaluated for each monomer and were found to depend upon the nature of the monomer. Reactivities of MMA and AAc toward grafting were compared with those of methyl acrylate (MA), ethyl acrylate (EA), and vinyl acetate (VAc) reported earlier from this laboratory and were found to follow the order MA > EA > MMA > VAc > AAc. An explanation for the observed order of reactivity of different vinyl monomers is presented.
Synthesis and characterization of rare earth metal‐containing polymers. I. Fluorescent properties of ionomers containing Dy3+, Er3+, Eu3+, and Sm3+
Authors: Banks E. , Okamoto Y. , Ueba Y.
Published: April 2003

Rare earth metal (Dy3+, Er3+, Eu3+, and Sm3+) salts of copolymers of methyl methacrylate–methacrylic acid, styrene–acrylic acid, 1‐vinylnaphthalene–acrylic acid and 1‐vinylanthracene–styrene–acrylic acid were prepared. The fluorescence of these polymer salts under ultraviolet excitation was investigated. The fluorescent intensity of polymer–Eu3+ films varied with film thickness because of incomplete absorption of exciting light, hence most of the measurements were made on pressed fine powders. The fluorescent intensity of mixed samples of Eu(III) acetate in a polymer matrix increased linearly with Eu content. However, the Eu3+–polymer complex system displayed typical concentration‐quenching behavior, reaching a maximum at 4–5 wt % Eu and decreasing with further increases in Eu content. This suggests that the ionomer contains ionic aggregates, in agreement with a recently proposed model. Such aggregates would create locally high Eu ion concentrations, whose interactions lead to concentration quenching at low nominal concentrations. The fluorescent intensity of the acrylic copolymers decrassed in the order methacrylate > styrene > naphthalene > anthracene. This sequence is explained by incrasing competition for the exciting light by the aromatic groups with negligible energy transfer from the aromatic groups to the Eu3+ ions. This is also consistent with the hypothesis that the ionic regions of the polymer are segregated.
Effect of photodegradation on dynamic mechanical properties of nylon 6
Authors: Yano Shoichiro , Murayama Mikio
Published: April 2003

Changes in the dynamic mechanical properties of nylon 6 (α‐form) under ultraviolet light irradiation were investigated. On irradiation with spectrally dispersed ultraviolet light in the wavelength range of 219–415nm, the dynamic modulus E′ and the density of nylon 6 were increased below about 300nm. It was found that the increment in E′ and the density were the result of crosslinking. When E′ was measured with time elapsed during irradiation by light of 253.7 nm, E′ initially decreased with time, increased at a longer time, and then reached a limiting value asymptotically. From the result of the change in E′ with time, it was assumed that the scission and crosslinking reactions occur simultaneously during ultraviolet light irradiation. Thus, the change in E′ with elapsed time was exppressed by the equation E′t = E′0 exp (−k1t) + E′∞[1 − exp (−k2t)], where E′t is the dynamic modulus at time t, E′0 is the E′ at t = 0, E′∞ is the limiting value of E′, and k1 and k2 are the rate constants. The apparent activation energies for k1 and k2 were 3.23 and 2.50 kcal/mole, respectively, and the former value agreed with the activation energy for the scission of the amide groups. The effects of the photodegradation on the temperature dispersion of nylon 6 were also investigated. On irradiation with light at 253.7 nm, the α‐relaxation which appeared at about 90°C was broadened and the intensity of the γ‐relaxation at −95°C in the tan δ‐versus‐temperature curve was lowered. The β‐relaxation which appeared at −45°C for the wet nylon 6 decreased its intensity.
Determination of mean molecular weight of polyethylene glycols by several physical methods
Authors: Taleb‐Bendiab Sid Ahmed , Vergnaud Jean‐Maurice
Published: April 2003

Several physical methods were used for the determination of the mean molecular weight of polyethylene glycols (PEG). Gas chromatography proved to be the best method to obtain a molecular weight of PEG lower than 600 by using Tenax as a stationary phase. Reverse gas chromatography was long but valid for PEG between 400 and 3000. Viscosity measurements gave more suitable values by taking different Mark–Houwink constants according to the molecular weight of PEG. Gel permeation chromatography using the universal calibration method was shown reliable, and by means of three μ‐Styragel phases (100, 500, and 104 Å) the molecular weight range between 200 and 20,000 was covered. Infrared measurements were related to the molecular weight by taking the OH absorbing band, and a result for PEG of 5000 or less was obtained. Vapor pressure measurements as made in tonometry were an accurate and sensitive method.
Absorption of benzene by open‐cell polyurethane foams
Authors: Sefton Michael V. , Mann John L.
Published: April 2003

The rate of absorption of benzene by open‐cell polyurethane foams of varying pore size (30–85 pores per inch) has been shown to be dependent on the size of the foam samples. Mass transport from the bulk vapor to the matrix surface appears to be a significant resistance when compared with the rate of diffusion in the matrix itself. Even though these foams have a large permeability to air at low pressures, pore diffusion appears to be more significant than bulk flow in describing the absorption process, resulting in absorption behavior which is more characterstic of closed‐cell foams. A dual resistance model of the obsorption process, has been used to estimate matrix diffusivities and pore mass transfer coefficients. Although the model was inadequate in some regards to describe completely the absorption process, the significance of the unexpected pore diffusion resistance to mass transfer was quantified. The dependence of pore diffusion on foam size reflected the qualitative interpretation that was apparent from the absorption curves. While the reason for this anomalous behavior remains unknown, open‐cell foams cannot be considered simply as a high‐surface‐area thin‐walled form of the matrix material in describing the absorption process; the effect of foam size must also be considered.
Wrinkle‐resistant cotton by photoinitiated reaction with glycidyl methacrylate followed by crosslinking reactions
Authors: Reinhardt Robert M. , Arthur Jett C. , Muller Linda L.
Published: April 2003

A wrinkle‐resistant cotton fabric was produced by photoinitiated free‐radical reaction of a glycidyl methacrylate monomer from a methanol‐water solution to form a poly(glycidyl methacrylate) copolymer, followed by crosslinking reactions of oxirane groups of the copolymer with cellulose. The product had increased conditioned and wet recovery angles and retained breaking and tearing strengths and stiffness values in the ranges normally obtained for wrinkle‐resistant cottons. The effects of these reactions on the fiber structure were determined by transmission electron microscopy. The modified fibers were resistant to dissolution in cupriethylenediamine dihydroxide.
UV‐irradiated ozonation of water‐soluble polymers
Authors: Imamura Seiichiro , Teramoto Masaaki , Ogawa Yukinobu , Teranishi Hiroshi
Published: April 2003

The effect of ultraviolet light on the ozonation of some water‐soluble polymers such as polyethylene glycol, polyacrylamide, carboxymethyl cellulose, and poly(vinyl alcohol) was investigated. Ultraviolet light irradiation accelerated the ozonation. Acceleration was caused by the decomposition of ozone by ultraviolet light, which produced active species.
Thermal degradation of polystyrene. I. Chain scission at low temperature in air
Authors: Gupta Mool C. , Nath Jaya D.
Published: April 2003

The thermal degradation of polystyrene was studied in air at temperature where volatile formation is neglible. Plots of degree of degradation α vs. t are linear and confirm the random nature of chain scission, but the intercepts are temperature dependent and the rate constant decreases with temperature, showing that oxygen plays a role in the chain‐end initiation and deactivation of the free‐radical centers. IR spectra indicate the formation of an acetophenone‐type structure during degradation. The kinetic analysis using various methods yield an activation energy value of 30–35 kcal/mole.
Permeation of oxygen through polyurethane–polyepoxide interpenetrating polymer networks
Authors: Chen Show‐An , Ju Hui‐Lin
Published: April 2003

Oxygen permeation studies on polyurethane (PU)/polyepoxide (EP) interpenetrating polymer networks show that the increased crosslinking density owing to additional permanent chain entanglement (resulting from interpenetration) can decrease the coefficients of permeation, diffusion, and oxygen solubility. At 20% PU, at which the crosslinking density is maximum, these coefficients retain minimum values, while the tensile strength retains a maximum value.
Compositional determination of 2,6‐dimethyl‐1,4‐phenylene oxide and styreen hompolymer blends by infrared spectrometry and pyrolysis gas chromatography
Authors: Mukherji Anil K. , Butler Marsha A. , Evans Donald L.
Published: April 2003

Compositional analysis of 2,6‐dimethyl‐1,4‐phenylene oxide (PPO) and styrene homopolymer blends was accomplished using infrared spectrometry and pyrolysis gas chromatography. In infrared measurements the 1030/700 cm−1 absorption ratio provides percent PPO in the blends within ±3% of the actual value but with a σ% of ±10. In pyrolysis GC measurements, four peaks resulting from the fragmentation of the PPO molecule have been investigated for quantitation. One of these peaks provides results with ±2% of the PPO present with a σ% of 7 when the percent PPO in the blend is above 20.
Sorption kinetics for asymmetric binary and ternary laminate slabs in finite and semi‐infinite well‐stirred baths
Authors: Spencer H. Garth , Barrie James A.
Published: April 2003

Equations describing the sorption kinetics of asymmertric membranes composed of AB and ABC laminate slabs in finite and in semi‐infinite well‐stirred baths are presented, and some properties of these systems are discussed.
Influence of diethylene glycol content on behavior of poly(ethylene terephthalate) fibers
Authors: Militký Jiří , Vaníček Jiří , Dostál Jan , Jansa Jaroslav , Čáp Jaroslav
Published: April 2003

Relationship between structural parameters of poly(ethylene terephthalate) (PET) fibers, their mechanical properties, and nonisothermal sorption of disperse dyes are investigated. Influence of diethylene glycol (DEG) addition and small changes in draw ratio are studied. Mechanical properties are characterized by stress–strain curves at constant deformation rate. The stress–strain relationships are described by means of derivative analysis. For treatment of nonisothermal experiments a simple kinetic model is suggested enabling to determine activation parameters of sorption. Further, the influence of a blank dye bath on the structure and properties of PET fibers is studied.
Cationic polymerization of α‐methyl styrene from polydienes. II. Tensile properties of poly(butadiene‐g‐α‐methyl styrene) and poly(styrene‐b‐butadiene‐g‐α‐methyl styrene) copolymers
Authors: Ambrose R. J. , Newell J. J.
Published: April 2003

Tensile properties of poly(butadiene‐g‐α‐methyl styrene) copolymers have been investigated on molded samples. These graft copolymers show thermoplastic elastomer behavior because of their graft copolymer structure. Both modulus and strength increase with increasing α‐methyl styrene content and tensile strength is highest at the 45–50% by weight α‐methyl styrene level. Tensile strength at elevated test temperatures is considerably higher for these poly(butadiene‐g‐α‐methyl styrene) copolymers than for styrene‐butadiene‐styrene triblock polymers. This is attributed to the higher glass transition temperature for poly(α‐methyl styrene) segments compared to polystyrene segments. The oil acceptance of these graft copolymers appears to depend on the number of loose polybutadiene chain ends. Thus, the tensile strength of oil‐extended poly(butadiene‐g‐α‐methyl styrene) copolymers was considerably lower than oil‐extended poly(styrene‐b‐butadiene‐g‐α‐methyl styrene) copolymers even though both copolymers contained equal hard segment contents.
Thermally stimulated discharge current studies on low‐temperature relaxation in epoxy resin
Authors: Su W‐F. A. , Carr S. H. , Brittain J. O.
Published: April 2003

Thermally stimulated discharge current (TSDC) analysis has been used to characterize the low‐temperature (100–300 K) molecular relaxation processes (β relaxation) of an epoxy resin. Experiments were performed on a resin system composed chiefly of tetraglycidyl‐4,4′‐diaminodiphenyl‐methane and diaminodiphenyl sulfone (TGDDM/DDS). Polarization of the epoxy of the resin appears to be due to preferential orientations of dipoles in the temperature range studied. The broad β‐dispersion peak exhibits considerable “structure,” and it promises to prove rich in information related to polarization and relaxation processes in the epoxy resins. It is seen that TSDC can reveal clearly the difference between the degree of curing for epoxy resins. Temperature dependence of a mean activation energy calculated from the discharging processes reveals several temperature ranges over which common molecular relaxation events are probably occurring.
Effect of free monomer content on the drawing behavior of poly(methyl methacrylate)
Authors: Hope P. S. , Duckett R. A. , Ward I. M.
Published: April 2003

Cold drawing has been used to produce oriented samples of various molecular weight grades of poly(methyl methacrylate), all of which exhibited marked strain hardening characteristics over a range of drawing temperatures. The differences between the yield and drawing behavior of the grades did not correlate with molecular weight but could instead be attributed to the plasticizing effect of additional free monomer, generated by degradation during melt processing of the polymer.
Chlorinated poly(vinylidene fluoride)
Authors: Bacskai R.
Published: April 2003

Chlorinated poly(vinylidene fluoride) (PVF2) was prepared by introducing chlorine gas into a CCI4 suspension of PVF2 at reflux temperature. Polymer crystallinity and softening point decrease, while solubility and adhesion increase with the degree of chlorination. In contrast to PVF2, the chlorinated polymer is soluble in low‐boiling common organic solvents, such as acetone, methyl ethyl ketone, and 1,2‐dimethoxyethane. Chlorinated PVF2 is resistant to dehydrochlorination and is thermally more stable than PVF, chlorinated PVF, PVC, or chlorinated PVC. Chlorinated PVF2 coatings on wood, prepared by solution casting at room temperature, show outstanding weathering resistance.
Analytical study of the additives system in polyethylene
Authors: Lehotay Jozef , Daněček Jaroslav , Líška Otakar , Leško Ján , Brandšteterová Eva
Published: April 2003

On the basis of standards of identification of substances in the additive system of polyethylene has been performed. Different methods for separation such as adsorption thin‐layer chromatography, high‐performance liquid chromatography with chemically bounded phases, and gas chromatography have been used. The fir al identification has been made with mass spectrometry. The substances have been extracted from polyethylene with hexane and chloroform.
Critical appraisal of the volume‐entropy‐energy equation for liquids
Authors: Doolittle Arthur K.
Published: April 2003

The author's six articles on VSE equation of state for liquids are summarized in tabular form, and certain conclusions, applicable to the lirection of research on plastics, are drawn.
Gel permeation chromatography using controlled‐porosity glass. II. Polyacrylamide aqueous solutions
Authors: Onda Nobuhiko , Furusawa Kunio , Yamaguchi Noriko , Tokiwa Masatoshi , Hirai Yasumasa
Published: April 2003

In a study of polyacrylamide in solutions we have required the rapid characterization on chromatographies. The application to the aqueous solution of the GPC using controlled‐porosity glass has been examined from both the viewpoint of the effect of salt addition and the GPC mechanism. An adequate addition to neutral salt, 0.005M KCI to the eluent, gave rise to the elution behaviors being in accord with the hydrodynamic volume concept of the GPC separation.
Sintering of latex particles in pigmented coatings. II. Influence of the latex particle size
Authors: Alince B. , Lepoutre P.
Published: April 2003

The light‐scattering coefficient S of coatings formulated from a mixture of an inorganic pigment and polystyrene latex particles may be enhanced significantly when the dry coating is heated in order to cause sintering of the polystyrene spheres. The relative increase in S depends on the size and the amount of the latex particles and the type of the inorganic pigment. Of the latexes examined (0.5, 0.2, 0.1, and 0.03 μm in diameter) the 0.2μm latex is the most effective in blends with platelike delaminated clay. The coatings based on spherelike precipitated calcium carbonate are less responsive to the heat treatment. The gloss of the clay–latex coatings is not significantly altered by the heat treatment up to 20 pph of latex; the gloss of the calcium carbonate coatings generally decreases upon heating.
Novel ion‐containing reverse osmosis membranes. I. Preparation and selected properties
Authors: Bittencourt E. , Stannett V. , Williams J. L. , Hopfenberg H. B.
Published: April 2003

Grafting and subsequent quaternization of 2‐and 4‐vinylpyridine to poly(vinyl chloride) (PVC) and to poly[3,3‐bis(chloromethyl)oxetane], Penton, films have been exploited to prepare novel ion‐containing membranes. 2‐Vinylpyridine‐grafted “Penton” films are the most attractive system for further study since the PVC grafts were unstable under the requisite extraction conditions. Although the sterically less hindered 4‐vinylpyridine‐grafted films were easier to quaternize, weight gain calculations indicated that complete quaternizations were only achieved with the 2‐vinylpyridine‐grafted films. High ionic concentrations were obtained in the grafted membranes. The mechanical properties of the wet films were measured. Salt absorption studies demonstrated that significant salt exclusion was achieved at relatively high salt concentrations although the grafted films sorbed up to 30 vol % water.
Rubber‐modified epoxies. II. Morphology and mechanical properties
Authors: Manzione L. T. , Gillham J. K. , McPherson C. A.
Published: April 2003

A wide range in morphology paralleling a spectrum of phase separated and dissolved rubber, can be developed in rubber‐modified epoxies through control of rubber‐epoxy compatibility and cure conditions. These morphologies result in different stress response mechanisms. Dissolved rubber promotes plastic deformation and necking at low strain rates that provide large increases in the elongation to break. Dissolved rubber is ineffective in providing improvement at impact rates. Phase separated rubber domains can also increase the elongation to break since cavitation is promoted at the interfacial boundary. The elongation is limited to the extent of cavitation and therefore large increases in the energy to break are not found. The presence of rubber domains was found to be a necessary but not sufficient condition for impact energy improvement. Optimum materials contained a relatively large amount of dissolved rubber and a low volume fraction of phase separated rubber. These combine high elongations at low strain rates with improved impact properties.
Reinforcement of siloxane elastomers by silicas. Comparison between fumed and precipitated silicas in their interactions with an oligomer of poly(dimethylsiloxane)
Authors: Berrod G. , Vidal A. , Papirer E. , Donnet J. B.
Published: April 2003

Comparison between fumed and precipitated silicas in their interactions with an oligomer of poly(dimethylsiloxane) showed both materials to exhibit general identical behavior depending on the experimental temperature range. However, the results obtained suggest on the one hand that these interactions are directed more by morphological and structural characteristics than by chemical properties and on the other hand that the distribution of surface silanol groups on precipitated silicas is not the same as on fumed silicas. Both siloxane‐modified fillers exhibit high thermal stability.
Effect of container diameter on β‐radiation‐induced polymerization of acrylamide
Authors: Verma Satyajit , Callihan Clayton D. , McIlhenny Robert C.
Published: April 2003

Beta particles emitted by radioactive nuclei have a finite depth of penetration in a given medium and hence a certain linear energy transfer value depending upon their initial energy. This property can be utilized to achieve different rates of radiation induced reactions. Various diameter capillaries containing saline solutions of acrylamide and radioactive phosphorus‐32 were used in the experiment and the change in viscosity of acrylamide solution was used as an indicator of the amount of energy transferred. Distinctly different rates were observed which were roughly proportional to the diameters of the capillaries containing the solutions. It also appears that irradiation of the polymer solution at 80°C even in the absence of oxygen has an adverse effect on the viscosity. The experimental conditions were chosen to approximate those existing in oil reservoirs.
A method of calculating copolymerization reactivity ratios
Authors: Kuo Jen‐Feng , Chen Chuh‐Yung
Published: April 2003

An improved linearization method is proposed for determining the monomer reactivity ratios of free‐radical copolymerizations by fitting the data of cumulative copolymer compositions and overall weight fractional conversions, or cumulative copolymer compositions and residual monomer compositions of the reaction mixture. The reactivity ratios of monomers for four different copolymerization reactions are determined. The results are very close to those of literature reports and account well for the experimental results.
Surfactant interactions in poly(vinyl acetate) and poly(vinyl acetate–butyl acrylate) latexes
Authors: Vijayendran B. R. , Bone T. , Gajria C.
Published: April 2003

Saturation adsorption and penetration adsorption of several anionic surfactants at model poly(vinyl acetate–;acrylate) latex/water interfaces are described. The effects of molecular weight and structure of anionic surfactants, latex composition, and the presence of adsorbed layers on latex particles on penetration type surfactant interactions leading to the formation of solubilized polymer–surfactant complex and latex thickening are considered. In the case of saturation‐type adsorption of nonionic surfactants, surfactant adsorption at a vinyl acrylic latex/water interface is correlated satisfactorily with the polarity of polymer surface, in agreement with earlier surfactant adsorption studies.
Gamma irradiation of polypropylene fibers in the presence of carbon tetrachloride
Authors: Ramanan G. , Rao M. H. , Rao K. N.
Published: April 2003

Polypropylene (PP) fibers have been irradiated with 60Co γ rays in the presence of carbon tetrachloride, in the absence of oxygen. Irradiations have been carried out between dose rates of 0.078 and 0.664 Mrad/hr, and the effects of absorbed dose and temperature on the CCl formation in the PP fibers have been investigated. G(CCl) values were higher at lower dose rate. G(HCl) values were found to be much higher than the G(CCl) values, and IR absorption studied indicated increasing unsaturation with increasing dose. The number average molecular weights (M̄n) were evaluated from intrinsic viscosity measurements in decalin at 408 K and the M̄n values decreased with increasing dose and temperature. G(scission) − G(crosslinking) values were calculated and it was found that the Gs − Gx values are higher at lower doses and higher dose rates. The thermal characteristics of the irradiated fibers were investigated by thermogravimetry (TG) analysis in air or argon and with differential scanning calorimetric (DSC) studies. The TG data indicated slightly less thermal stability for the modified fibers both in air as well as argon. The DSC data indicated very little change in the melting points of the samples, the melting points being around 444 ± 2 K.
Catalytic effect of a portland cement filler on the cure of water‐compatible resorcinol phenol–formaldehyde polymer concrete
Authors: Sugama T. , Kukacka L. E. , Horn W.
Published: April 2003

Aggregate with a water content <1 wt % is normally needed for the production of polymer concrete (PC). This increases the cost and complexity of the process. In this study, PC with a compressive strength of >2000 psi (>13.78 MPa) at an age of 1 hr at 24°C was produced by mixing resorcinol phenol–formaldehyde (RPF) resin with portland cement and aggregate containing 1–10% water. The addition of ∼14.7–17.5% type III portland cement to the PC formulation produced an acceleration in the rate of the condensation‐type polymerization reaction and improved the properties of the composite. The cause of the accelerative effect was found to be the electropositive bivalent metallic ions of calcium and magnesium released from the cement grains in an aqueous medium. Conversely, the trivalent metallic ions from cement such as Al3+ and Fe3+ have no effect on the rate of polymerization of RPF resin.
Reaction with metal ions of chloromethylated polystyrene resin containing dithiocarbamate group
Authors: Hiratani Kazuhisa , Onishi Yasuhiro , Nakagawa Tsutomu
Published: April 2003

The derivatives of poly(chloromethylstyrene) resin (PCMS) with N‐methyl‐N‐carboxylmethyl‐dithiocarbamate (1), N,N‐di(β‐hydroxyethyl)dithiocarbamate (2), N‐methyl‐N‐carboxylmethylamino (3), and di(β‐hydroxyethyl)amino (4) groups were prepared, and the metal ion reactivity of the polymer resins with these functional groups were investigated. Additionally, the effect of γ irradiation on the reaction with metal ion was also investigated. In the reaction of PCMS under the same conditions, the substitution ratio order is as follows: (2) > (1) > (4) > (3). In the reaction of the resins with cupric ion, the reaction amount reached a maximum of 4.17 mequiv/g for resin (1) and 4.75 mequiv/g for (2). The polymers containing sulfur atom have a large reactivity toward metal ion in comparison to the polymers without sulfur atom. The reactivity of polymer (1) toward metal ions decreased in the following order: Ag(I) ≫ Cu(II)> Zn(II) ≳ Ni(II) ≳ Co(II). The other metal ions, except Ag(I) and Cu(II), hardly reacted with polymer (2). Thus, polymer (2) has a remarkable selectivity. It was also found that the reaction amount of polymers containing sulfur after γ irradiation is almost the same as that before γ irradiation.
Rapid measurements of elastic modulus and density in polypropylene sheet during aging
Authors: Baum J. S. , Schultz J. M.
Published: April 2003

New methods for rapidly obtaining elastic modulus and density measurements during isothermal polymer aging are given. The elastic measurements are performed using a Rockwell hardness tester. In this case, the elastic recovery is measured. Rapid density measurements are performed using a “double drop” density gradient columan method. Here, a fully aged and a freshly quenched specimen are dropped simultaneously into the column. Simultaneous column height differences directly measure the density difference of the two specimens. The results of these two experiments extend previously reported aging measurements to relatively low times of aging. A log (time) law for both properties is found to the smallest times measured.
Studies on suspension and emulsion. XLVI. Emulsifier‐free emulsion polymerization of styrene in acetone–water
Authors: Okubo Masayoshi , Yamada Akira , Shibao Susumu , Nakamae Katsuhiko , Matsumoto Tsunetaka
Published: April 2003

Emulsifier‐free emulsion polymerization of styrene in acetone–water medium was carried out using potassium persulfate as initiator. Below acetone content of 40 vol %, stable emulsion was prepared and polymerizations were remarkably fast compared with those in pure water. The particle size decreased from 0.5 to 0.17 μm with an increase in acetone content in the range 0–40 vol %, and the distributions were very sharp. The optimum polymerization for the preparation of the stable emulsion was: styrene, 20 vol %; acetone/water, 40/60 (v/v); KPS, 3.4 × 10−3 mole/l; temp., 90°C.
Glass‐reinforced composites of antifouling organotin epoxy polymers
Authors: Subramanian R. V. , Williams R. S.
Published: April 2003

The use of a new class of thermoset organotin epoxy polymers as matrix resin for composites has been evaluated. Copolymers of maleic anhydride with hexene‐1, decene‐1, or styrene were partially esterified with tributyltin, and the residual carboxyl groups were crosslinked with glycidyl methacrylate when preparing glass fabric‐reinforced composites. Glass composites were also prepared from DGEBA cured by tributyltin 3,5‐diaminobenzoate. The tensile, flexural, and impact strengths of the composite specimens warrant their use in structural applications requiring antifouling protection.
Local disturbances preceding a running crack front in a viscoelastic solid
Authors: Kobayashi Akira , Munemura Masayuki , Ohtani Nobuo
Published: April 2003

The local disturbances ahead of a running crack front in a viscoelastic solid were measured through noncontact electro‐optical tools. It was observed that the very high local strain rate up to 200/sec exists even in the present quasistatic loading case. It may be concluded that the running crack propagation velocities, not the conventional average strain rates ranging from about 10−4/sec to 10−2/sec, govern the local disturbances, as the crack propagation velocities always exceed 200m/sec for both average strain rates, while the local strain rates observed do not show much differences between both average strain rate cases.
Electric strength of epoxide resins and its relation to the structure
Authors: Takahama Takashi , Hayashi Osamu , Sato Fumihiko
Published: April 2003

Epoxide resins having various ratios of ether and ester bonds were investigated as to the relation between electric strength and polymer characteristics. The electric strength over a wide range of temperature is presented here. A marked reduction of strength characteristics of the epoxide resins occurs at a critical temperature indistinguishable from the glass transition temperature Tg, which is related to the free volume and molecular relaxation process. At temperatures exceeding Tg, the electric strength has a strong dependence on polymer structure, film thickness, and applied pulse width. This behavior is considered to obey the thermal breakdown mechanism, and it is assumed that the ion is important in the precursory region of electric breakdown.
Permeation of gases through modified polymer films. V. Permeation and diffusion of helium, nitrogen, methane, ethane, and propane through γ‐ray crosslinked polyethylene
Authors: Macdonald R. W. , Huang R. Y. M.
Published: April 2003

The permeation and diffusion of helium, nitrogen, methane, ethane, and propane through γ‐irradiated polyethylene films were investigated. These studies were carried out with two objectives in mind: (1) to determine the effect of crosslinking by γ irradiation on permeability and diffusivity using the gas molecules as molecular probes; and (2) to study the plasticizing effects of the low hydrocarbons on the polyethylene film. The γ‐ray‐induced crosslinking efficiency of polyethylene was investigated in the following irradiation atmospheres: vacuum, acetylene, and nitrogen–acetylene mixtures. Results showed that irradiation in acetylene decreased the crosslinking efficiency while an acetylene–nitrogen atmosphere increased the efficiency compared to irradiation in vacuum. Both the permeation constants and the diffusion coefficients were found to decrease with increasing irradiation dose while the activation energies increased. The permeation constants of the organic gases through polyethylene increased with molecular diameter while the diffusion coefficients decreased. This increase in permeability was attributed to an increase in the solubility due to solubilization of the membrane by the penetrant. For example, the molecular diameter of propane is 4.397 Å compared with 2.807 Å for methane; however, propane permeated the polyethylene film at a rate twice that of methane. Nitrogen and methane have approximately the same molecular diameters—2.7085 and 2.807 Å, respectively—but owing to the plasticizing effect of methane, it permeated the film at a rate three times greater than that of nitrogen. It is interesting to note that the stronger the plasticizing ability of the penetrant, the greater the effect of the irradiation dose. The permeability of propane decreased by 40.7%, while the permeability of helium decreased by 6.4% after an irradiation dose of 50 Mrad.
Solubility of isobutane in two high‐density polyethylene polymer fluffs
Authors: Parrish W. M. R.
Published: April 2003

Solubility and rate of desorption of isobutane vapor in high‐density polyethylene (HDPE) polymer fluff and a HDPE‐hexene‐1 copolymer fluff for isotherms between 65.5 and 93.3°C are reported. The data were obtained for pressures to near the vapor pressure of isobutane. Solubilities were correlated using Henry's law, Flory–Huggins theory, and weight fraction activity coefficients. The last approach gave the best correlation of data over the entire temperature and pressure range. The estimated rate of sorption of isobutane is 1.5 × 10−4 mol iC4H10/g fluff/bar/min over the range studied.
Cellular affinity of polyamides having various functional groups. I. Platelet adhesion
Authors: Ogata Naoya , Sanui Kohei , Tanaka Hozumi , Takahashi Yoichi , Sakurai Yasuhisa , Akaike Toshihiro , Okano Teruo , Kataoka Kazunori
Published: April 2003

Various polyamides having a different density of hydrogen bonding, of hydrophilic character, and containing ionic groups have been synthesized and their blood compatibilities were evaluated in terms of the adhesion behavior of blood platelets on polyamide by the microsphere column method. Polyamides containing anionically charged groups such as carboxylate or sulfonate groups adsorbed fewer blood platelets than those with undissociated carboxylate groups. Polyamides having thioether groups adsorbed fewer platelets than those having ether groups. Introduction of a rigid piperazine unit caused an increase in platelet adhesion.
Rheological and extrusion characteristics of glass fiber‐reinforced polycarbonate
Authors: Knutsson B. Anders , White James L. , Abbas Kent B.
Published: April 2003

An experimental investigation of the rheological properties of glass fiber‐reinforced polycarbonate melts and the extrusion of such compounds through capillary and slit dies is presented. The viscosity–shear rate function seems independent of instrument for cone‐plate and capillary investigations. The presence of fibers increases the level of the viscosity. Normal stresses at fixed shear stress are also increased by the presence of fibers. The extrudate swell is decreased by the presence of fibers and surface roughness is increased. Fiber orientation increases and surface roughness decreases with increasing extrusion rate.