bluuebunny/crossref_metadata_2025 huggingface dataset:
Dielectric and dynamic mechanical behavior of poly(vinyl acetate) containing small concentrations of cholesteryl additives
Authors: Deshpande D. D. , Kandaswamy N. R. , Tiwari V. K.
Published: April 2003

Dielectric loss measurements at four temperatures and as a function of frequency are presented for the poly(vinyl acetate) (PVAc) systems containing small concentrations of cholesterol, cholesteryl acetate, cholesteryl oleate, cholesteryl nonanoate, cholesteryl benzoate, cholesteryl oleyl carbonate, p‐methoxy benzilidine‐p‐n‐butyl aniline, diphenyl ether, and cetyl acetate. For the first five systems, the α‐relaxation temperature for sure PVAc was found to be increased in the presence of the said additives. The results of the dielectric depolarization spectroscopy at 1 kHz and the dynamic mechanical analysis also conform with these observations. It is inferred that the segmental motion in PVAc is hindered by these first five additive molecules through a specific dipolar interaction. These additives are therefore described as antiplasticizers to PVAc as they extend the glassy region over a wider temperature interval. The analysis of the dielectric data to give the dielectric decay function and the β parameter reveals that the two types of the additives, viz., plasticizers and antiplasticizers, can be distinguished by the opposite signs obtained for the ratio Δβ/ΔC, where C is the concentration. The analysis based on the WLF theory shows that the WLF reference temperature T0 is higher than that for pure polymer if the additive is an antiplasticizer while the same is lower for the plasticizing additives. The apparent enthalpy of activation for the dielectric relaxation process is found to be higher in the case of additives which show antiplasticization of PVAc.
A new hydrostatic compression tester for anisotropic filled polymers
Authors: Lepie Albert H. , Moran Mark B.
Published: April 2003

This paper describes a testing device designed for measuring the isotropic or anisotropic hydrostatic compression properties of filled polymers like solid propellants, including the initial void content and the bulk modulus. The propellant test samples used are either cubical, cylindrical, or rectangular specimens. Three pressure‐sealed linear variable differential transformers (LVDTs) are used to monitor the dimensional changes of a cube specimen during hydrostatic pressurization simultaneously in the XYZ directions. The moduli E11, E22, and E33 and the compression strain ratios v21, v32, and v31 can be determined as a function of pressure. The three LVDTs can also be used to measure the length changes of three rectangular or cylindrical test specimens under hydrostatic compression only in the vertical Z direction. The bulk modulus and void content can be computed when isotropic behavior is assumed. The entire test procedure is controlled by an Apple II microcomputer via an AI13 12‐bit analog input system. Some typical test results obtained with undamaged and damaged propellant samples are described.
Ion pair–ion pair and ion–dipole interactions in polyurethane–styrene blends
Authors: Rutkowska M. , Eisenberg A.
Published: April 2003

It is shown that ion pair–ion pair interactions can be utilized to achieve miscibility in blends of urethanes with styrene ionomers. The urethanes contain quaternary ammonium salts in the hard segments, while the styrenes contain sodium methacrylate groups (∼9.6 mol %). By contrast, ion–dipole interactions are not strong enough to achieve miscibility enhancement; a polyurethane containing short (ethylene oxide) sequences in the hard segment did not exhibit miscibility with a styrene–lithium methacrylate copolymer.
Mechanical and friction properties of glass‐filled thermoplastics modified by polyethylene additives
Authors: Lipatov Yu. S. , Petrenko S. D. , Privalko V. P.
Published: April 2003

Temperature and concentration dependences of elasticity modulus, wear and wearability of industrial glass‐filled thermoplastics modified by low‐density polyethylene were studied. It is shown that polyethylene additive reduces the elasticity modulus in the solid aggregate state of polymer matrix and enhances it in the softening region. For the first time a possibility was found to reduce friction, wear, and wearability of glass‐filled thermoplastic materials by incorporating optimum amount of alloying polymer additive thermodynamically incompatible with the polymer matrix.
Ternary copolymers of hemin, styrene, and 1‐vinylimidazole or 1‐vinyl‐2‐methylimidazole as cyanide ion exchanger
Authors: Kokufuta Etsuo , Watanabe Hiroshi , Saito Kiyoshi , Nakamura Isei
Published: April 2003

Ternary copolymers, involving hemin (H) (ferri‐protoporphyrin IX chloride), styrene, and 1‐vinylimidazole (VI) or 1‐vinyl‐2‐methylimidazole (VMI) in the different proportions, were synthesized by radical copolymerization. All the copolymers obtained were insoluble in aqueous solvents. No dissolution of H from the copolymers was observed even when the extraction with 0.5N NaOH or HCl was allowed to continue for a total time of 50 days. To clarify the functional capabilities of the ternary copolymers as a cyanide ion exchanger, the adsorption of cyanide ion onto the copolymers was investigated at different pHs. The amount (Acn) of the adsorbed cyanide ion was found to be dependent on the content of H residue in the copolymer, thus indicating that the adsorption site for the cyanide ion consists of ferri‐protoporphyrin IX (FP). Another important feature is that Acn increases in proportion to the VI or VMI content of the copolymer. This result was discussed in terms of the coordination structure of the FP and also of the coordination reaction of cyanide ion to the FP.
Determination of graessley's relaxation time in concentrated polymer solutions and melts
Authors: Quadrat Otakar , Prokopov´ Eva
Published: April 2003

The method consists of a comparison between experimental data and Graessley's theoretical function of the dependence of viscosity of concentrated polymer solutions and melts on the velocity gradient in a linearized plot using a three‐parameter empirical equation. The procedure is objective and allows the use of a computer.
Effects of uniaxial drawing and heat‐treatment on gas sorption and transport in PVC
Authors: El‐Hibri M. J. , Paul D. R.
Published: April 2003

Sorption and transport measurements for various gases in rigid poly(vinyl chloride) were made following uniaxial drawing and heat treatment. The permeabilities of He, Ar, N2, and CH4 were found to be essentially independent of pressure in PVC while CO2 showed a complex pressure dependence which varied with prior exposure and degassing history. Sorption isotherms were analyzed by the dual mode sorption model, and the parameters obtained were correlated with the Lennard–Jones potential‐well depth of the gas. The Henry's law coefficient for CO2 was found to be significantly larger than expected which is believed to be the result of a specific interaction with PVC. Uniaxial drawing of PVC above its glass transition caused significant reductions in gas permeabilities, of which roughly one‐third is attributable to the accompanying heat treatment rather than molecular orientation per se. The physical state of the polymer was characterized by density, birefringence, and calorimetry. Changes in gas sorption and permeation behavior are discussed in terms of these results.
Optimization of batch polymerization processes—narrowing the MWD. II. Experimental study
Authors: Louie Brian M. , Soong David S.
Published: April 2003

Programmed solvent injection was previously proposed and analyzed in the first part of this two‐paper series as a viable alternative for controlling the average molecular weight and narrowing the polydispersity of products from a free‐radical polymerization process with an inherent tendency to exhibit strong gel and glass effects. Here, methyl methacrylate is chosen for experimental verification of this idea. The product molecular weight distribution is indeed narrowed.
Surface characterization of styrene/acrylamide copolymer latex particles
Authors: Tamai H. , Murakami T. , Suzawa T.
Published: April 2003

Surface characteristics of styrene/acrylamide copolymer latex particles prepared without emulsifier were investigated as a function of acrylamide fraction in charged monomers. The presence of swelling or water‐soluble polymer layer at the particle surface was suggested, and its thickness increased with increasing acrylamide fraction. The surface charge densities by conductometric and potentiometric titrations wer about half that of polystyrene latex particles at low pH and they increased slightly with increasing pH. Regarding the heterocoagulation between styrene/acrylamide copolymer latex particles and polystyrene latex particles, the critical coagulation concentration of KCI decreased with increasing acrylamide fraction. The consideration in terms of the interaction due to electrostatic and van der Waals forces also suggested that the swelling or water‐soluble polymer layer at the particle surface plays an important role.
The application of coherent optics to the study of adhesive joints II. Holographic interferometry
Authors: Vallat M. F. , Smigielski P. , Martz P. , Schultz J.
Published: April 2003

The technique of holographic interferometry is complementary to the technique of speckle photography described previously. It allows the out‐of‐plane motion to be visualized with a sensitivity of about 0.3 μm. This technique has been applied to the study of the behavior of model glass‐glass joints bonded by different adhesives under shear stress. Its high sensitivity allowed the presence of stress concentrations at the ends of the joints to be shown in the case of high‐modulus adhesives and the existence of additional torsion and/or cleavage stresses to be demonstrated in the case of lower modulus adhesives. Work in progress should lead to more quantitative data.
Polymeric reaction of acrylic polymer–monomer system irradiated by low‐energy electron beam. II. Effect of ester structure of acrylic polymer
Authors: Takiguchi Ryohei , Uryu Toshiyuki
Published: April 2003

Polymeric reactions of polyacrylate–benzyl acrylate (BzA) systems induced by a low‐energy electron beam were investigated by changing the species of polyacrylates added to the system. The gel fraction, the proportion of BzA units incorporated into gel by infrared (IR) analysis, and the molecular weight and its distribution curves by gel permeation chromatography (GPC) were examined to elucidate the reaction mechanism for the polymer–monomer system. The GPC curves were detected by both ultraviolet (UV) and refractive index (RI). As the UV‐detected GPC curves represent the benzyl groups of graft polymers and homo polymers, the polymerization reactions can be followed by GPC. Ester structures of acrylic polymers were varied in order to examine how much the ester group affects such individual reactions as crosslinking, graft polymerizations, and homopolymerizations. In the case of both polyisobutylacrylate–BzA and poly(isoamyl acrylate)–BzA systems, the crosslinking and graft reactions predominated, while in the case of poly(t‐butyl acrylate)–BzA systems, homopolymerization was the main reaction. These results can be explained by the structure and reactivity of polymer radicals and viscosity of the system.
Behavior of cyanoethylated cotton towards gamma radiation
Authors: Hebeish A. , Zahran A. H. , El‐Naggar A. M. Kh.
Published: April 2003

Unmodified cotton fabric, cyanoethylated cottons having 0.12, 0.55, 0.77, and 1.24% N as well as cotton treated with NaOH under conditions similar to those of cyanoethylation but in absence of acrylonitrile were exposed to gamma radiation doses (3.199–31.199 Mrads). The six substrates before and after irradiation were assessed for copper number, carboxyl content, degree of polymerization, tensile strength, and elongation at break to determine the extent of degradation of these substrates. The effect of radiation dose on the nitrogen content of cyanoethylated cottons was also examined. It was found that degradation is higher the higher the radiation dose irrespective of the substrate used. Nevertheless, the extent of degradation is determined by nature of the substrate. Introduction of cyanoethyl groups in the molecular structure of cotton cellulose impart certain resistance to radiation degradation of cotton provided that these groups are present in appreciable amounts (0.55% N and above). The cyanoethyl groups seems to impede oxidation of the cellulose hydroxyls and/or glucosidic bonds against radiolysis. On the other hand, when present in smaller amounts, the cyanoethyl groups are not able to outweigh the increased accessibility of cotton cellulose brought about by the alkaline environment of the cyanoethylation reaction. Hence, substrates containing lower cyanoethyl contents are more susceptible to degradation than the modified cotton, and in this respect they are similar to alkali‐treated cotton.
Characterization of poly(vinyl alcohol)
Authors: Bugada Daniele C. , Rudin Alfred
Published: April 2003

Molecular weight distributions, long chain branching frequency, and solution viscosities of samples of commercial poly(vinyl alcohol) (PVA) are reported. The PVA was fully reacetylated to poly(vinyl acetate) (PVAc) for characterizations by size exclusion chromatography using a low angle light scattering detector. The Mark–Houwink constants for PVAc in toluene were determined to be K = 0.106 cm3 g−1 and α = 0.59, at 25°C. Long chain branching frequency in the commercial PVAs studied was small and was little affected by polymer molecular weight. Some 95% or more of the branches in these species were short. Aqueous solutions at 10% (w/v) of PVA were Newtonian. The polymers examined differed in chemical composition, molecular weight distributions, and mean block lengths of vinyl acetate residues. Variations in a single characteristic, like a solution or intrinsic viscosity, cannot be used to deduce structural differences between PVAs.
Metal ion additive–polyimide interactions employing thermogravimetry
Authors: Rancourt J. D. , Taylor L. T.
Published: April 2003

Solutions of poly(amic acid), a polyimide precursor prepared from 3,3′,4,4′‐benzophenone tetracarboxylic acid dianhydride and 4,4′‐oxydianiline, containing metal ions such as Pd, Pt, and Sn in a variety of chemical states were prepared. The polymer–metal ion solutions and each component thereof were analyzed by thermogravimetry. Summation of the calculated contribution of each component of the polymer solution mass loss curve yields a calculated TG curve. Subtraction of the calculated curve from the actual curve for the polyamic acid–metal ion solution results in a difference TG curve. From the difference TG curve information about polymer/additive interactions can be obtained.
On the chain cross‐sectional area and motion of macromolecular chains
Authors: He Tian‐Bai
Published: April 2003

This paper attempts to relate the chain cross‐sectional area to the glass transition temperature of a polymer and to discuss the effect of the chain cross‐sectional area in view of the motion of molecular chains. It has been found that the definite relationship between glass transition temperature and cross‐sectionalarea can be obtained only when taking account of intermolecular interaction of polymer chains. It is considered that the chain cross‐sectional area will characterize the chain flexibility of a polymer since the glass transition temperature is related both to intermolecular interaction and chain flexibility of a polymer. The concept of the structural parameter cross‐sectional area per chain, first introduced by Vincent1 and used by Boyer and Miller,2–5 is useful in empirically correlating properties and structures of polymers. The glass transition temperature is a basic parameter of bulk polymers and is characteristic of their intermolecular interactions and chain flexibility. This paper attempts to relate chain cross‐sectional areas to glass transition temperatures of polymers and to discuss the effect of the chain cross‐sectional area in view of the motion of molecular chains.
Viscoelastic properties of elastic polyurethaneureas in the curing process
Authors: Raszczuk A. , Kozakiewicz J. , Orzechowski A.
Published: April 2003

Dynamic viscoelastic properties of a system, NCO‐terminated polyurethane–aniline–cresol–formaldehyde liquid resin were studied during the curing process using an R‐17 Weissenberg Rheogoniometer. For gel time determinations a new method was developed, the gel time being then difined as the cure time when the relaxation time τ = 3 s at a frequency of 0.1 Hz was achieved. The dynamic storage modulus G′, the dynamic viscosity η´ and the relaxation time τ have been determined as functions of curing time. The effects of cure temperature and of curing agent concentration on G′, η′, and τ were studied. The influence of cure temperature on the gel time and on the visco‐elastic properties determined at 18ks (5 h) of curing was discussed. Based on the experimental results, it was concluded that curing at higher temperature led to the more crosslinked polymer. Activation energy values for the gel time were also determined and compared with the values for polyurethanes and polyurethaneureas reported elsewhere. A relationship between the relaxation time and the effect of frequency on modulus G′ was presented, and it appeared to be independent of cure temperature, curing agent concentration, and curing time, being then presumably a useful method for comparative studies of viscoelastic behavior of different materials in curing process. This relationship was compared with the approximate relationship between tan δ and d In G′/d In ω given by Staverman and Schwarzl. The agreement at shorter relaxation times and some discrepancy at longer times were obtained.
Effect of structural changes of cotton by acid hydrolysis and crosslinking on soiling and soil release
Authors: Hebeish A. , Nasr H. I. , Abdou L. A. , El Sheltawi S. T. , Haggag K.
Published: April 2003

The effect of acid hydrolysis (0.5N HC1 at 60°C for 5–90 min) on the soiling and soil release properties of cotton fabric before and after crosslinking was investigated. The effect of acid hydrolysis of crosslinked cotton under similar condition on the same properties was also undertaken. Crosslinking with and without nonionic softener was carried out using dimethylol dihydroxyethlene urea and magnesium chloide hexahydrate as a catalyst. Aqueous and nonaqueous oily dispersions of carbon black were used for soiling. Results of these studies disclosed that acid hydrolysis prior to crosslinking imparted aqueous and oily soil resistance to the cotton, particularly during the very initial stages of hydrolysis treatment. Crosslinking of cotton and acid‐treated cottons in the absence of softener accentuated soil resistance. The opposite holds true for crosslinking in the presence of softener. Short acid treatment of cotton before and after corsslinking decreased the ability of cotton to release the aqueous and oily soils. On the other hand, acid hydrolysis of crosslinked cotton improved aqueous and nonaqueous soil‐resistance provided that the duration did not exceed 30 min. Hydrolysis accentuated also the ease of oily soil removal, but aqueous soil release was adversely affected. The results were interpreted in terms of changes in the physical and chemical structures of cotton and crosslinked cottons brought about by acid hydrolysis.
Rheological properties, shrinkage and melt spinning instability of blends of linear polyolefins with low density polyethylene
Authors: Santamaria Anton , White James L.
Published: April 2003

A comparative study is presented of the influence of addition of a long chain branched low density polyethylene LDPE on the rheological and processing characteristics of a high density polyethylene (HDPE), a polypropylene (PP), and a polybutene‐1 (PB). The influence of the LDPE on the PP and PB are most striking. Substantial increases in normal stresses, “shrinkage” of extruded filaments, and melt spinning stability are observed. The effects are much smaller for the HDPE blends.
Blends of poly(vinyl acetate) and poly(ethyl methacrylate): Some mechanical properties
Authors: Olayemi J. Y. , Ibiyeye M. K.
Published: April 2003

Poly(vinyl acetate) (PVAc) and poly(ethyl methacrylate) (PEMA) were solution blended in chloroform and cast into films on mercury surface. Some mechanical properties of the films were studied with the Instron Testing Machine. Tensile strength (TS), initial modulus (IM) and elongation at break of the films were found to depend highly on blend composition, and increased above the values for the pure polymers, each showing a peak at about 20% PEMA. The peak values of TS, IM, and elongation at break depended on an important factor, (Mv)rc the ratio of the molecular weights of (PEMA) to (PVAc). Improvements to the mechanical properties of the polymers due to blending were considered to be as a result of the presence of favorable and strong (PVAc‐PEMA) intermolecular interactions which reveal miscibility and compatibility of the polymers. A lower critical value (Mv)rc of 4.9 was found, above which no phase separation would be expected on blending these two polymers to the extent of 20% by weight of PEMA.
Moisture regain and dyeability of poly(acrylic acid)‐ and poly(styrene)‐carbamoylethylated cotton graft copolymers induced by gamma radiation
Authors: Hebeish A. , Zahran A. H. , El‐Naggar A. M. K. , Rabie A. M.
Published: April 2003

Gamma radiation‐induced graft copolymerization of either acrylic acid or styrene onto untreated cotton, alkali‐treated cotton, and carbamoylethylated cottons having 0.392% N, 0.524% N, 0.725% N, 1.379% and 1.546% N was investigated under different conditions. Moisture regain and dyeability of these substrates before and after copolymerization were also examined. It was found that the graft yield increases by increasing monomer concentration and radiation dose irrespective of the monomer or substrate used. Using water‐ethanol mixtures as polymerization media are advantageous for grafting of styrene. With both monomers, however, the graft yield for the modified cottons are substantially higher than untreated and alkali‐treated cottons, indicating that the presence of carbamoylethyl in the molecular structure of cotton cellulose affords additional sites for graft copolymerization. Copolymers obtained using acrylic acid show much higher moisture regain that the ungrafted substrates, particularly when the carboxylic groups of the graft were in the sodium form. The opposite holds true for copolymers brought about by grafting with styrene. The color strength of all substrates dyed with a direct or a reactive dye decreases significantly after copolymerization with poly(acrylic acid) prior to dyeing. On the other hand, this copolymerization improves the affinity of the substrates for the basic dye and brings about perceptible shade. Copolymerization of the substrates in question with poly(styrene) improves the color strength of these substrates when dyed with direct, disperse, and basic dyes but decreases the color strength upon dyeing with a reactive dye.
New aspects in cationization of lignocellulose materials. III. Influence of delignification on reactivity and extractability of TMAHP–hemicelluloses
Authors: Ebringerová Anna , Antal Miroslav , Šimkovic Ivan , Micko Michael M.
Published: April 2003

Beech sawdust samples with different lignin content were alkylated with 3‐chloro‐2‐hydroxypropyltrimethylammoniumchloride (CHMAC). The yields and the degree of subtitution of trimethylammonium‐2‐hydroxypropyl (TMAHP) samples were similar. Differences were found in extractability of hemicelluloses from this materials both with water and dilute alkali. To obtain the maximum yield of TMAHP–hemicelluloses (ca. 90% of the amount originally present), it is sufficient to remove about 50% of lignin. The lignin component does not influence the reactivity of hemicelluloses. The isolated hemicelluloses differ only in the distribution of functional groups and extractability.
Rheological studies of ultraviolet curing with an oscillating plate rheometer
Authors: Otsubo Yasufumi , Amari Takeshi , Watanabe Koichiro
Published: April 2003

The dynamic viscoelastic behavior during UV curing was studied for thin liquid films of epoxy acrylate prepolymer by the use of an oscillating plate rheometer. The dynamic viscosity rapidly increases after a certain period of irradiation, so that the UV curing process has the minimum exposure energy required to start polymerization. The minimum exposure energy markedly increases with increasing sample thickness; this results from the inconsistency of degree of curing in the direction perpendicular to the shearing surface. Since free radicals which initiate polymerization are formed by photochemical decomposition of initiator, the ability to cure a film depends on the light intensity at a given depth of the film. the attenuation of light in the film is primarily responsible for this inconsistency. When UV light is applied through a UV filter, the curing behavior is analyzed by a single exponential decay of light with depth because the curing is induced by absorption of a monochromatic light of 365 nm. On the other hand, when UV light from a UV lamp whose output spectrum is a continuum is directly applied, the curing behavior is explained by a combination of energy absorption at different wavelengths. In both cases, the theoretical curves of dynamic viscosity predicted in relation to spectral sensitivity show a good agreement with the experimental results.
Structural differences exhibited by networks prepared by chemical and photochemical reactions IV chemical relaxation
Authors: Haidar B. , Vidal A. , Donnet J. B.
Published: April 2003

Chemical stress relaxation has been used for the characterization of elastomeric networks obtained either by peroxide curing or by photocrosslinking. It has been shown that the differences observed between photocrosslinked and peroxide‐cured elastomers are not limited to their structure and physical properties but are also due to the very nature of the created bonds.
Drawing of nylon‐6 by the novel incremental drawing process
Authors: Misra Ashok , Dutta Bhaskar , Prasad V. Kali
Published: April 2003

Multifilament nylon‐6 fibers are drawn by the novel incremental drawing process as well as by the conventional drawing process. In this process the fibers are stretched in 36 stages along the surface of two corotating cones fitted on the incremental drawing machine. Fibers are obtained from each stage, and from their diameter measurements it is shown that they are stretched in a predicted manner. Mechanical properties, as measured by Instron and by a sonic modulus tester, show higher tenacity and modulus values for the incremental process than for the conventional one at equivalent draw ratios. Structural properties are analyzed by density measurements, wide angle X‐ray diffraction and birefringence. These showed higher crystallinity and higher crystalline as well as amorphous orientation factors for the incremental process at equivalent draw ratios. The mechanical property results are explained on the basis of structural development during drawing. It has been shown that the incremental drawing process is a suitable technique for obtaining superior properties in fibers and has commercial potential.
Topographic orientation on buffed polymeric substrates: The mechanism of wax buffing
Authors: Pence S. B. , Sporer A. H.
Published: April 2003

This paper reports on the observation that buffed waxy polymers control the orientation of a vapor‐deposited material subsequently deposited thereon. The insight into the mechanism of the buffing process of waxy polycrystalline polymers that these observations provide is presented. When a polycrystalline waxy polymer is buffed, grooves are formed. The dimensions of the grooves on the waxy polymer surface are substantially finer than the dimensions of the fibers of the buffing cloth. It is proposed that the buffing process stretches the polymer sufficiently to cause fibrillation, which results in the fine grooves observed. The fine grooves provide the topography necessary for orientation of the material deposited thereon.
Efficiency of antioxidants in thick‐walled natural rubber samples evaluated by differential scanning calorimetry and compression stress–relaxation
Authors: Stenberg B. , Björk F.
Published: April 2003

The effect ot two antioxidants, IPPD and DENA, on the aging properties of TMTD‐vulcanized natural rubber was studied by DSC. In the case of IPPD, the results were compared with mechanical measurements. The DSC measurements were carried out on specimens taken at different depths from cylindrical samples. The decrease in oxidative induction time was less pronounced for IPPD than for DENA at the edge of the samples. In the interior, the opposite behaviour was observed.
Temperature dependence of sorption parameters near Tg for propane in a miscible blend of polystyrene and poly(vinyl methyl ether)
Authors: Yavorsky J. A. , Spencer H. G.
Published: April 2003

The sorption of propane by 75:25% (w/w) miscible blends of polystyrene and poly(vinyl methyl ether) with different thermal histories was investigated near Tg. The dual‐mode sorption model was used to analyze the results. The evidence indicates that the Henry's law constant for states below Tg cannot be smoothly extrapolated from the rubbery state.
Fiber of poly(vinyl alcohol) derived from vinyl trifluroacetate. III. Production and properties of fibers
Authors: Yamaura Kazuo , Mizutani Ittsusei , Monma Kumiko , Tanigami Tetsuya , Matsuzawa Shuji
Published: April 2003

The direct wet‐spinning of syndiotacticity‐rich poly(vinyl alcohol) from ammonolysis solutions of poly(vinyl trifluoroacetate) was carried out. The high draft in spinning could not be accomplished at lower and higher polymer concentration, but it was accomplished at a certain middle polymer concentration. The drawn fibers with high draft have not always high strength. The fibers with high strength were obtained from fibers wound at moderate draft in spinning and then drawn at higher times without solvent. The strength was independent on the degree of polymerization (in a range from DP = 1870 to DP = 5580), but it became higher in the case of thinner fibers obtained from the solutions of lower polymer concentration. Here, the highest Young's modulus and strength at break were 13.8 GPa and 12 gr/denier, respectively.
The mass burning rate of flame‐retarded polypropylene in an oxygen‐enriched atmosphere
Authors: Spilda I. , Košík M. , Blažej A.
Published: April 2003

Polypropylene containing a bromophosphorous flame‐retardant exhibits a higher mass burning rate—in the atmosphere containing more than 30 vol % of oxygen — than nonretarded resin. These prodegradative reactions in combustion can be eliminated only by using a high concentration (ca. 40 phr) of inorganic alumina trihydrate. A method for distinguishing the physical and chemical effects of flame retardants is described.
Adhesive behavior of the two phase system: Polyisobutylene–sodium carboxymethylcellulose
Authors: Pigłowski J. , Kozłowski M.
Published: April 2003

Adhesive properties of polyisobutylene filled with sodium carboxymethylcellulose have been studied. From the results obtained by the removing cylinders method the lifetimes of the cylinder–PIB/CMC composition joint were calculated. The compositional dependence of the lifetimes have a similar character to that representing the dependence of relaxation time on the composition.
Copolymers of ethylene with butene‐1 and long chain α‐olefins, III. Hexadecene‐1 as long chain α‐olefin
Authors: Seppälä Jukka Veli
Published: April 2003

Hexadecene‐1 was used as comonomer with ethylene in a slurry polymerization with Ziegler–Natta catalysts. Hexadecene contents remained at less than 4 wt % in ethylene/hexadecene‐1 copolymers. When butene‐1 was also present in the polymerization, hexadecene‐1 contents were significantly higher. With hexadecene content of 11 wt %, the terpolymer density was 910 g/dm3. The effect of butene addition was significantly smaller with less than 10 carbon atoms containing α‐olefins.
Combustion products from polydiallylamine
Authors: Galbraith M. N. , Hodgkin J. H. , Vit I.
Published: April 2003

Crosslinked polydiallylamine (Sirorez Au1) was prepared by the redox‐initiated (K2S2O8/TiCl3) polymerization of freshly distilled diallylamine [containing 2% 1,6‐bis(N,N‐diallylamino)hexane] as a 30% solution in 80% phosphoric acid at 0°C. The resulting crosslinked resin is thoroughly washed with water and then sodium hydroxide solution (10%) before a final distilled water washing and air drying.

Polydiallylamine resin containing ≃ 50% by weight gold was prepared by soaking the above resin in a three fold molar excess of gold cyanide solution (2 g/L at pH 8.5) overnight and then filtering the resin, washing with distilled water, and air drying. The samples were dried for 24 h over P2O5 before combustion.
Shear and thermal history effects in polypropylene melts
Authors: Schertzer Richard , Rudin Alfred , Schreiber Henry P.
Published: April 2003

Fiber grade polypropylenes with melt flow indices of 3 and 12 were studied in the aspolymerized (powder) state and after pelletization. Pelletizing operations caused very little change in the molecular weight distributions of these polymers. The lower melt flow index material exhibited much greater apparent viscosity and melt elasticity in the powder than in the pellet from during screw extrusion at 190°C. These results are consistent with the existence of a higher entanglement density in the powder version. Instron rheometer data showed no difference between the two polymer forms because of the possibility for entanglement in the rheometer reservoir during rheological experiments. The effects of sample history noted with the 3 melt flow polymer were less pronounced with the lower molecular weight 12 melt flow material. The differences in flow curves of powder and pelletized forms of the latter polymer were negligible at 175 and 190°C. Differences in die swell were more noticeable, however. The effects observed are attributable to reversible shear‐induced decreases in entanglement density. Similar phenomena have been reported for other polymers. The results reported here have implications in quality control procedures for thermoplastics and in the production of polymers with desired property balances.
Chemical conversion of wood to thermoplastic material
Authors: Morita Mitsuhiro , Sakata Isao
Published: April 2003

A chemically modified wood meal (CE‐wood) was prepared by cyanoethylation in the presence of alkaline salts. The temperature Tf at which the wood could flow was measured by a simple mechanical flow tester. The CE‐wood demonstrated thermal flow at around 250°C. The Tf value decreased with increasing cyanoethyl content of the wood. Treatment of the wood meal before cyanoethylation with sodium periodate or sodium chlorite lowered Tf. The flow temperature was also decreased by blending the CE‐wood with appropriate synthetic polymers or plasticizers. Treatment of CE‐wood with chlorine solution was found to be the most effective method of lowering Tf. The Tf value of the slightly chlorinated CE‐wood (Cl content=2%) was about 100°C lower than that of the original CE‐wood. The lowering of Tf for CE‐wood by treatment with chlorine may be interpreted in terms of the plasticizing effect of chlorination on the lignin moiety in the wood.
A comparison of some rheological properties of concentrated solutions of chlorinated polyethylene and polyvinyl chloride in dioctyl phthalate
Authors: Muñoz M. E. , Peña J. J. , Santamaría A.
Published: April 2003

Steady‐state and transient shear flow properties of poly(vinyl chloride) and chlorinated polyethylene dissolved in dioctyl phthalate were studied at different temperatures and polymer concentrations. In the case of poly(vinyl chloride)/dioctyl phthalate systems the presence of a sol–gel transition temperature was observed, whereas for chlorinated polyethylene/dioctyl phthalate systems the mechanism of flow was the same in the whole range of temperatures and concentrations. On the basis of the data obtained for both polymer/solution systems, we conclude that the presence of crystallites, rather than hydrogen bonds, determines the rheological behavior of poly(vinyl chloride)/dioctyl phthalate systems.
Analysis of the accuracy of determination of molar mass distribution by the GPC with the on‐line light‐scattering detector
Authors: Procházka Ondřej , Kratochvíl Pavel
Published: April 2003

The effect of errors of the concentration (c‐) and the light‐scattering molar mass (M‐) detector in gel permeation chromatography (GPC) on the accuracy of the determination of the molar mass distribution (MMD) was analyzed. Model calculations showed that the reliability of MMD obtained from c‐detector data and from a carefully performed calibration dependence is higher than that obtained by combining data of the M‐ and c‐detectors. A criterion of the uncertainty of the MMD determination by the GPC method with the M‐detector was suggested, and its dependence on MMD parameters of the analyzed polymer and on the magnitude of injection was investigated.
Epoxy resin cure III: Boron trifluoride catalysts
Authors: Smith R. E. , Smith C. H.
Published: April 2003

Boron trifluoride forms complexes with nitrogen‐and oxygen‐containing Lewis bases. These acid–base complexes are sometimes added to epoxy resins to accelerate their cure at elevated temperature (120°C–160°C). Several possible processing concerns with the use of boron trifluoride complexes have been investigated. It was shown that each complex can be readily identified by its distinct fluorine‐19 NMR spectrum. All of the boron trifluoride complexes are converted to fluoroboric acid under normal epoxy resin cure conditions. The fluoroboric acid is the true catalyst for epoxy resins. Experimental results show that fluoroboric acid does not catalyze the polymerization of an epoxy resin at room temperature. Finally, it was shown that fluoroboric acid is not hydrolyzed to hydrofluoric acid.
Mass loss of wood and its components during transmission electron microscopy
Authors: Mary M. , Revol J.‐F. , Goring D. A. I.
Published: April 2003

The loss of mass of wood and its polymeric constituents in transmission electron microscopy has been determined by measurement of the decrease in the continuum x‐ray intensity for various doses of irradiation. It was found that for doses higher than 5 × 10−8 C/μm2, 42% of the original mass of the wood remained on the grid. The corresponding percentages for cellulose, xylan, and lignin were 32, 45, and 70, respectively. The significance of these results in the use of transmission electron microscopy for imaging and for quantitative microbeam analysis is discussed.
Photoregulated sorption dyes to polymers. II. Adsorption of acid yellow 38 to hydrophilic polymers and its light‐induced desorption
Authors: Petrak K. , Leyshon L. , Douglas P.
Published: April 2003

Adsorption of Acid Yellow 38 to, and its light‐induced desorption from, various coated polymer layers in water have been studied. Diffusion studies were used to determine the degree of competitive binding between the dye and polymers. It was found that the extent of both adsorption and desorption were different for polymer mixtures as compared to single polymer films. The presence of gelatin crosslinked within the polymer layer increased the amount of dye desorbed upon irradiation.
The role of intumescence on the flammability of vinyl and vinylidene polymers
Authors: Impallomeni G. , Montaudo G. , Puglisi C. , Scamporrino E. , Vitalini D.
Published: April 2003

Thermal stability and flammability properties of six structurally related vinyl and vinylidene polymers fail to show correlation. Instead, it is found that the combustion of these polymers is dominated by their char‐forming ability. A remarkable intumescent effect is observed in PVC2, PVF2, and PVC which accounts for the high flame extinguence of these polymers.
Grafting acrylonitrile and acrylic acid monomers on cellulosic materials
Authors: Okieimen Ebhodaghe F. , Ebhoaye Justus E.
Published: April 2003

Graft copolymers of acrylonitrile and of acrylic acid monomers on cellulosic materials were obtained by use of ceric ion initiator in aqueous medium at a 50% (w/w) cellulose‐monomer ratio. The variations of poly(acrylonitrile) grafts and of the efficiency of grafting with ceric ion concentration, and of poly(acrylic acid) grafts with temperature are examined. The dependence of water retention capacity of the grafted fibers with the graft level is reported.
Preparation and morphology of a silicone‐acrylate copolymer system
Authors: Williams Todd R.
Published: April 2003

This paper presents the synthesis and analysis of a new series of silicone acrylate (SiAc) copolymers. The building block oligomers are linear polydimethylsiloxanes with alkylene urethane methacrylate end groups (Mn 1000–3000). A variety of analyses were performed in order to elucidate the morphology of these copolymers. Data are presented from differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), permeability testing, small angle x‐ray scattering (SAXS), and electron microscopy. These data indicate that these co‐polymers possess a two‐phase morphology in the range of compositions studied. Conclusions are drawn about the continuity, shape, and size of the domains. Some comparisons are made between data for these “ladder” polymers and data for siloxane‐containing alternating block copolymers reported in the literature.
Durability of radiation‐sterilized polymers III. Oxidation layer determined by chemiluminescence
Authors: Yoshii Fumio , Sasaki Takashi , Makuuchi Keizo , Tamura Naouki
Published: April 2003

Chemiluminescence (CL) analysis was used for determining the oxidation layer formed by the irradiation of polypropylene for medical supplies. The depth of the oxidation layer from the surface depended on dose rate and increased with decreasing dose rate. The oxidation occurred remarkably at a region near the surface area of the film where the diffusion of oxygen is more sufficient. On the contrary, there was very little oxidation in the interior portion. The oxidation layers of polypropylene samples irradiated with electron beam showed U‐shaped profiles in the cross‐section of film as did as a sample irradiated with γ‐rays. However, the degree of oxidation by irradiation with electron beam was very small; CL intensity at the surface area was only one‐third that for the γ‐irradiated samples.
Sorption of N‐butane, propane, and ethane in ethylcellulose
Authors: Casur Ertugrul , Smith Theodore G.
Published: April 2003

The sorption of n‐butane, propane, and ethane in ethylcellulose has been investigated between 0 and 200 mm Hg pressure over the temperature range from 30 to 70°C. Sorption isotherms of n‐butane, propane, and ethane in ethylcellulose suggest that both Henry's law and the Langmuir forms of sorption, are operative. Sorption data were analyzed using the dual sorption model and sorption parameters determined. The sorption attributed to the Langmuir mode decreases as the temperature increases. This result indicates that the nonlinear Langmuir mode of sorption is more characteristic of the glassy state than sorption represented by the Henry's law mode. It was found that sorption attributed to the Henry's law and Langmuir modes decreases as the molecular size of gaseous hydrocarbon penetrants decrease. In this study, the molecular size of gaseous molecule decreased as the gases studied changed from n‐butane to propane to ethane. A correlation of the Henry's law constants for the solution of n‐butane, propane, and ethane in ethylcellulose with the Lennard‐Jones force constants, ϵ/k at different temperatures was also determined. The temperature dependence of the Henry's law constants were correlated by a van't Hoff relationship and heats of sorption determined.
(Photo) graft copolymerization of methyl methacrylate (MMA) on polyamine‐modified oxycellulose in a limited aqueous system
Authors: Ghosh Premamoy , Bandyopadhyay Arup Ratan
Published: April 2003

Graft copolymerization of methyl methacrylate (MMA) on oxycellulose modified with a polyamine [diethylene triamine (DETA)] was studied in a limited aqueous system under photoactivation in visible light using K2S2O8 as the intiator. No polymerization was observed in the dark or in presence of light in 80 min in the case of DETA‐treated cellulose; however, ready graft copolymerization resulting in high percent grafting and grafting efficiencies took place in the case of DETA‐modified oxycellulose system under photoactivated conditions. DETA‐modified oxycellulose prepared from oxycellulose corresponding to low degrees of oxidation (copper nos. 1.5–3.5) produced optimum grafting. The grafting parameters under different sets of conditions were studied and compared, and the mechanism of graft copolymerization was discussed.
Ultrasonic detection of segmental relaxations in thermoplastic polyurethanes
Authors: Aziz A. W. , Lawandy S. N.
Published: April 2003

The change in attenuation of longitudinal waves has been measured as a function of frequency and temperature for thermoplastic polyurethanes of different hardness covering a range from rubbery hardness to plastic. Analysis of the results show some segmental relaxations and the activation energies were calculated from the ultrasonic measurements. These activation energies were indirectly related to the fatigue failure of the polymer. This failure was expressed as cut growth.
Effect of degradative treatments on cotton graft copolymers. Part V. Behavior of poly(acrylamide)‐cotton graft copolymers toward acid treatments
Authors: Hebeish A. , El Rafie M. H. , Khalil E. M. , Abdel‐Hafiz S. A.
Published: April 2003

Polyacrylamide (Aam)‐cotton graft copolymers having 9, 14.5, and 20% graft were synthesized using ferrous cellulose thiocarbonate‐hydrogen peroxide redox system. These copolymers as well as ungrafted and initiator‐treated cottons were subjected to acid treatments (0.5 N HCl) at 40°, 60°, and 80°C for 15‐90 minutes. Hydrolytic susceptibility of the five substrates was assessed by monitoring carboxylic groups, copper, number, nitrogen content (in case of the copolymers), and tensile strength. Results obtained concluded that the copolymers exhibit higher resistance to acid hydrolysis than the ungrafted and initiator‐treated cottons. This was explained in terms of involvement of the CONH2 groups of the graft in an interaction with HCl.
Studies of selective adsorption resin. XXIV. Preparation and properties of macroreticular chelating resins containing both polyethylenepolyamine side chains and mercapto groups
Authors: Egawa Hiroaki , Nonaka Takamasa
Published: April 2003

The macroreticular chelating resins containing both polyethylenepolyamine side chains and mercapto groups were prepared by the reaction of 2,3‐epithiopropyl methacrylate‐divinylbenzene macroreticular copolymer beads with polyethylene‐polyamine. The adsorption behavior of metal ions on the obtained resins was then investigated. The amination of the macroreticular copolymer beads could effectively be carried out by treatment of the polymer beads with polyethylenepolyamine in organic solvent (benzene, terahydrofuran) or in the absence of organic solvent at 80°C or 100°C for 60 min. It was found that the adsorption capacity of the resins for metal ions is not only affected by the ion exchange capacity of the resins but also by the porosity of the resins. Hg2+, Ag+, and Cu2+ were effectively adsorbed on the resins even at a pH below 3, whereas Co2+, Ni2+, and Cd2+ were adsorbed at a pH above 3, Mn2+ at a pH above 7, and Ca2+ at a pH above 8. These metal ions adsorbed on the resins could easily be eluted with dilute mineral acid solution or dilute mineral acid solution containing thiourea.