bluuebunny/crossref_metadata_2025_split huggingface dataset:
Glycidyl methacrylate and N‐vinyl‐2‐pyrrolidone copolymers: Synthesis, characterization, and reactivity ratios
Authors: Soundararajan S. , Reddy B. S. R. 
Published: April 2003

AbstractFree radical copolymerization of glycidyl methacrylate (GMA) and N‐vinyl‐2‐pyrrolidone (VPD) was carried out using 2,2′‐azobisisobutyronitrile (AIBN), in chloroform at 60°C. The polymers were characterized by IR and 13C‐NMR spectroscopic methods. The percentage composition of the copolymers were established by microelemental analysis and by 13C‐NMR spectroscopy. The copolymerization reactivity ratios were computed using the Fineman‐Ross method, the Kelen‐Tudos method, and the extended Kelen‐Tudos method. The molecular weights of the copolymers were obtained by GPC measurements. Thermal properties of the homo‐ and copolymers were also studied by thermogravimetric analysis. The copolymers were tested as adhesives for leather‐to‐leather and leather‐torubber bonding.
Investigation of the relationship between conductivity and protein‐binding properties of polypyrrole
Authors: Smith Abraham B. , Knowles Christopher J. 
Published: April 2003

AbstractPolypyrrole was synthesized using two different methods of chemical synthesis to obtain a product with different electrical conductivity values. The two products were found to possess about the same ability to bind protein. After prolonged exposure to aqueous solutions of different ionic composition and at different pH values, the polymer was tested for electrical conductivity and protein‐binding ability. Electrical conductivity was found to vary with the conditions under which the polymer was stored, and of these, the pH of the medium was found to be the most important. On the other hand, the ability to bind protein did not show any such variation and only chemical reduction of the polymer produced a significant reduction in the level of protein binding.
Glow‐discharge‐induced graft polymerization of acrylic acid onto poly[1‐(trimethylsilyl)‐1‐propyne] film
Authors: Masuda Toshio , Kotoura Masaaki , Tsuchihara Kenji , Higashimura Toshinobu 
Published: April 2003

AbstractGraft polymerization of acrylic acid onto poly[1‐(trimethylsilyl)‐1‐propyne] [poly(TMSP)] film was examined. The water contact angle of poly(TMSP) film decreased remarkably from 90 to 15° by plasma treatment, which gradually increased up to 40° after several days. When the film exposed to a glow discharge was heated in an aqueous solution of acrylic acid at 80°C for 24 h, graft polymerization proceeded on the film surface, which was confirmed by ATR‐IR and ESCA spectra. Graft polymerization effectively occurred above a threshold temperature (80°C). The water contact angle of the grafted film was about 30°, and did not change with time. In contrast, when a poly(TMSP) film exposed to UV irradiation was heated in an aqueous solution of acrylic acid, graft polymerization took place not only on the film surface but also inside the film.
A study using 13C CP/MAS NMR of microstructural changes in acrylate copolymers due to photolytic/SO2 degradation
Authors: Schadt R. J. , Gilbert R. D. , Fornes R. E. 
Published: April 2003

AbstractPhotolytic degradation (350 nm) of acrylate‐type copolymer films in the presence of SO2 and H2O has been examined using 13C CP/MAS NMR. Copolymers in this study are used as binders in the paint and adhesives industry. The compositions contain butyl acrylate, vinyl acetate, vinyl chloride, and methyl methacrylate units in various combinations. Elemental analyses of the samples allow comparisons and confirmations of structural changes observed in the NMR spectra. A significant result is identification of pendant sulfate group incorporation in UV/SO2/or UV/SO2/H2O‐exposed VAc/BA‐type copolymers which has been attributed to a co‐unit interaction between BA and VAc units. It is suggested that effects on Tg, the glass transition temperature, may account in part for this co‐unit effect on photodegradation.
Transient length dilation vs. transient increase in permeability of natural rubber films
Authors: Pope D. S. , Koros W. J. , Jagur‐Grodzinski J. 
Published: April 2003

AbstractAir dissolved under pressure in a film, made from natural rubber, causes its slight dilation. Sudden decompression of this film leads to its large transient dilation that afterwards vanishes within less than a minute (τ ≈ 20 s). Such transient expansion is apparently caused by internal stresses due to oversaturation. This behavior is analogous to the previously reported transient increase in the permeability to gases of the suddenly decompressed polymeric membranes. A clear correlation between results derived from the dilation and the permeability measurements seems to be evident.
The sol/gel contribution to the behavior of γ‐irradiated poly(vinylidene fluoride)
Authors: Rosenberg Y. , Siegmann A. , Narkis M. , Shkolnik S. 
Published: April 2003

AbstractPoly(vinylidene fluoride) films were γ‐irradiated in the dose range of 1–20 Mrad, resulting in up to 74% gel. The irradiated polymer undergoes both crosslinking and chain scission, about 5 : 3 events, respectively. Swelling measurements indicate an increasing crosslink density with the gel content, already at the lower doses. Thermal analysis of the gel fraction and the unextracted irradiated samples shows that although crosslinking affects the crystallization, degree of crystallinity, and the melting characteristics, the behavior of the crosslinked material is predominantly controlled by the extractable sol fraction which consists of the more mobile original chains, branched chains, and degraded ones. The crosslinks, already at low density, retard the development of ordinary crystalline polymer morphology.
Thermal degradation studies of perchlorate‐doped conductive polymers
Authors: Neoh K. G. , Kang E. T. , Tan K. L. 
Published: April 2003

AbstractThe thermogravimetric behavior of polypyrrole (PPY), polybithiophene (PBT), and poly‐aniline (PAN) perchlorate complexes and their corresponding base polymers have been studied. The PBT–perchlorate complex and base polymer decompose at significantly lower temperatures than do the PPY and PAN counterparts. All three perchlorate complexes retain half or more of their original conductivities with no changes in the doping levels after one cycle of heating to 150°C in air and cooling to room temperature. However, after heating at 150°C for 24 h, only the PAN–perchlorate complex shows no significant change in the doping level, although its conductivity decreases by more than two orders of magnitude. X‐ray photoelectron spectroscopy analyses of the perchlorate complexes reveal the presence of at least two distinct chlorine species. The thermal decomposition of the perchlorate anions results in the formation of volatile chlorine species as well in chlorine covalently bonded to the polymer. The thermal decomposition of the PPY–perchlorate complex also results in the conversion of positively charged nitrogens to iminelike structures.
Relation between low‐frequency dielectric behavior of cellulosic materials and their inorganic contaminations
Authors: Moteleb M. M. Abdel , Shinouda H. G. 
Published: April 2003

AbstractResults are given for dielectric constant and loss factor of some cellulosic materials of different fine structure free of and contaminated with water‐soluble inorganic salts in the frequency range 0.1–100 kc/s and at temperatures 283.15–333.15 K. The analysis of the results reveals that the dielectric dispersion and loss peak found before with medicated cotton and viscose rayon, of ash contents of 0.3 and 1.4% respectively, disappear when these fibers have been “cleaned up” from inorganic impurities by acid washes. These anomalous dielectric behaviours reappear again with “cellulose‐inorganic salts” admixtures. Based on these findings, it has been concluded that the secondary relaxation process observed in the low‐frequency region 0.1–1 kc/s with cellulosic materials contaminated with inorganic impurities is not intrinsic but extrinsic in nature due to the displacement of ions adsorbed in the inner surfaces of such interstitial conduction system.
Segmental orientation behavior of flexible water‐blown polyurethane foams
Authors: Moreland J. C. , Wilkes G. L. , Turner Robert B. 
Published: April 2003

AbstractThe ambient temperature structure–property orientation behavior in two different polyureaurethane polymers (one cross‐linked and one linear) was measured by using infrared dichroism along with mechanical response. Thin films (plaques) thermally compression‐molded from TDI‐polypropylene (PO) flexible water‐blown polyurea‐urethane foams and solution‐cast TDI–PO polyurea–urethane elastomers were studied. Segmental orientation was measured as a function of elongation and relaxation, as well as of hysteresis behavior. The level of strain was 50–70% for the plaques and up to 240% for the elastomer. The soft segments for both materials exhibited a low state of orientation with elongation. Small changes in orientation with time and upon cyclic straining were also observed for the soft segments. Significant transverse orientation upon stretching was observed in the hard segments of the plaques and up to elongations of 100% for the elastomer. The transverse behavior of the hard segments in the plaques pressed from the foams was attributed to both the smaller hard domains as well as to the polyurea aggregates that have been reported to be present in flexible foams. This transverse behavior also suggested that the smaller hard domains and the polyurea aggregates possess a lamellarlike structure. At low strain levels (up to 50%), only small amounts of orientation hysteresis as well as mechanical hysteresis were observed for the hard segments of the plaques as well as for the elastomer. No significant relaxation in orientation was detected for the hard segments of both materials at a 30% strain level.
Preparation, morphology, and deformation behavior of polyoxypropylene‐co‐nylon 6 thermoplastic elastomers
Authors: Sikkema D. J. 
Published: April 2003

AbstractSegmented block copolymers consisting of nylon 6 and polyoxypropylene blocks were prepared and characterized. Pronounced phase separation in the solid phase was deduced from differential calorimetry and from small‐angle X‐ray scattering, as well as from dynamic mechanical measurements. The morphology (from X‐ray diffraction) and anisotropy in mechanical properties strongly suggest phase separation in the melt (which is optically clear). Elastomerlike properties are described and discussed.
Thermoplastic elastomer by radiation grafting. I. Evaluation of processability of natural rubber grafted methyl methacrylate
Authors: Razzak Mirzan T. , Yoshii Fumio , Makuuchi Keizo , Ishigaki Isao 
Published: April 2003

AbstractProcessability of thermoplastic elastomer (TPE) prepared by radiation‐induced grafting of methyl methacrylate (MMA) onto radiation vulcanized natural rubber latex (RVNRL) has been evaluated using a kneader and a hot roll mill at 150°C. It was found that mixing time and revolution rate (rpm) of the kneader have significantly affected the processability. The longer mixing time and the higher revolution rate result in better processability. In such processing conditions, however, the mechanical properties were found to be inferior because the molecular chain scissions occurred during the mixing. A considerable improvement of mechanical properties was obtained when the mixing was carried out without added process oils. Blends of the grafted vulcanized natural rubber latex (RVNRL‐g‐PMMA) and MMA grafted on unvulcanized natural rubber latex (NRL‐g‐PMMA) improved processability where the better processability could be achieved at a shorter mixing time and a lower revolution rate. In addition, a comparable value of mechanical properties was obtained.
The copolymerization of vinyl chloride with 1‐olefins. V. Heat stability of copolymers of vinyl chloride with propene, 1‐butene, and 1‐pentene
Authors: Mrázek Zdenĕk , Lukás̆ Rudolf , Pr̆ádová Olga 
Published: April 2003

AbstractCopolymers of vinyl chloride with propene, 1‐butene, and 1‐pentene containing 2–15 mol % of 1‐olefinic structural units were prepared. The copolymers were dehydrochlorinated at 180°C in an inert atmosphere; the amount of hydrogen chloride split off was determined by continuous potentiometry. The results show that the heat stability of propene, 1‐butene, and 1‐pentene copolymers containing the same amount of 1‐olefinic structural units does not differ significantly. Compared with the homopolymer of vinyl chloride, it is favorably affected by the presence of 1‐olefinic structural units in poly(vinyl chloride) (PVC) chains. On the other hand, however, the heat stability of copolymers is impaired by the higher content of structural defects able to initiate the dehydrochlorination reaction. These structural defects, probably represented by chloroallyl groups, are formed in the copolymers during their synthesis. At the beginning of heating, structural defects produce intensive dehydrochlorination and, therefore, copolymers of vinyl chloride with 1‐olefins if processed appear to be less thermally stable than does PVC.
Relationship between extrusion condition and mechanical properties of FRPP
Authors: Chiu Wen‐Yen , Lu Hsiang‐Chung , Chang Chia‐Lu 
Published: April 2003

AbstractIn this work, the relationship between extrusion condition and mechanical properties of glass‐fiber‐reinforced polypropylene (FRPP) was investigated. It was found that the extrusion flow rate was higher but the extrusion pressure was lower as the fiber content decreased. The flow rate and pressure were more temperature‐sensitive at high screw speed. As for the mechanical strength of FRPP, the yield strength decreased with increasing the fiber content, but modulus and impact strength significantly increased with increasing the fiber content. The high screw speed did not affect the mechanical strength of PP, but decreased the strength of FRPP. At higher extrusion temperature, the yield strength and modulus of FRPP increased, but the impact strength decreased. The yield strength and modulus of extrudates along the longitudinal direction of extruder were always higher than those along other directions by the effect of fiber orientation. The specimens taken from different positions of extrudate would show different mechanical strength. The way of cooling for the extrudates would affect the mechanical properties of FRPP, too. All the above relations were discussed and well explained from the contribution of fiber distribution, fiber length, crystallinity of PP, and void content.
Mechanical properties of multifilaments in different measurement conditions
Authors: Zurek W. , Jasińska A. , Frydrych I. , Jakubczyk J. 
Published: April 2003

AbstractStarting from Zhurkov's and Bartenev's theories and connecting them with Bailly's theorem and the structural analysis based on the rheological model, a method of determination of parameters describing the durability of multifilament is presented. Experiments carried out on polyester and polyamide filament yarns confirmed proposed method.
Structures and gas separation properties of asymmetric polysulfone membranes made by dry, wet, and dry/wet phase inversion
Authors: Pinnau Ingo , Koros William J. 
Published: April 2003

AbstractIntegrally skinned asymmetric gas separation membranes were prepared by (i) dry, (ii) wet, and (iii) dry/wet phase inversion processes. The membranes were cast from a polysulfone/methylene chloride/1,1,2‐trichloroethane/2‐methyl‐2‐butanol casting system. Wet and dry/wet phase inversion membranes were quenched in methanol. Membranes made by dry/wet phase inversion using convective evaporation showed optimum gas separation performance. The average O2/N2 and He/N2 selectivities of these membranes were within 85% of those determined for a dense, solution‐cast polysulfone film, suggesting that the ultrathin skin layers were essentially defect free. The average apparent skin layer thickness of all samples tested was 270 Å. Scanning electron photomicrographs revealed that optimum membranes made by dry/wet phase inversion consist of an ultrathin skin layer, a tightly packed nodular transition layer, and an open‐cell, sponge‐like substructure. Dry/wet phase inversion membranes prepared by free‐standing evaporation resulted either in high flux and low selectivity membranes or essentially defect‐free membranes with fluxes lower than those made by convective evaporation. Dry‐phase inversion membranes exhibited extremely low gas fluxes due to thick (17.5 μm) skin layers. On the other hand, wet phase inversion membranes showed O2/N2 selectivities < 1, indicating that gas transport was determined by pore flow through skin layer defects.
Modification of epoxy resins with poly(aryl ether ketone)s
Authors: Iijima Takao , Tochimoto Takuya , Tomoi Masao 
Published: April 2003

AbstractPoly(aryl ether ketone)s were used as modifiers for bisphenol‐A diglycidyl ether epoxy resin (AER 331) cured with methyl hexahydrophthalic anhydride. Poly(phthaloyl diphenyl ether) (PPDE), soluble in the uncured epoxy resin without using solvents, was prepared by the Friedel‐Crafts reaction of phthaloyl chloride and diphenyl ether. The mechanical, thermal, and dynamic viscoelastic properties of the modified resins with PPDE were examined and compared to the parent resin (AER 331). The fracture toughness, KIC, for the modified resins increased at no expense to their mechanical and thermal properties on 10 wt % addition of PPDE with molecular weights of more than 17,000. The toughening mechanism is discussed based on the morphological and dynamic viscoelastic behaviors of the modified epoxy resin system.
N‐(carboxymethyl) trimellitimide–based polyesterimides as film formers for air‐drying protective coatings
Authors: Kishanprasad V. S. , Gedam P. H. 
Published: April 2003

AbstractN‐(carboxymethyl) trimellitimide, the imidodicarboxylic acid, was prepared by the reaction between trimellitic anhydride and glycine. This was subsequently condensed in N‐methyl‐2‐pyrrolidone with the alcoholysis products obtained from linseed oil and glycerine to get different oil length polyesterimide resins. The drying characteristics of the resins and the physicochemical properties of the clear and the iron oxide pigmented coatings were evaluated. The results indicate that these materials form a promising class of film—formers for coatings of good durability and protective properties.
Thermal cis–trans isomerization of azo dye chrysophenine in cellulose matrices: Effect of morphology
Authors: Seves Alberto , Romanó Maria , Dubini‐Paglia Ernestina , Beltrame Pier Luigi , Marcandalli Bruno 
Published: April 2003

AbstractFilms obtained from native cellulose synthesized by Acetobacter xylinum and from cellulose obtained from cuproammoniacal solutions (cellulose II) were morphologically characterized by studying the cis‐trans isomerization of azo dye Chrysophenine dispersed in their amorphous region. The kinetic measurements of the reaction showed that both films behave as glassy polymers in the temperature range explored (36–66°C). In going from native cellulose to cuproammoniacal cellulose, an increase of the isomerization rate was observed, revealing a more homogeneous distribution and likely larger extent of free volume in the amorphous phase of cellulose II.
Swellable hydrogel matrices for the release of the pendent chain‐linked active ingredients over extended time periods
Authors: Shah S. S. , Kulkarni M. G. , Mashelkar R. A. 
Published: April 2003

AbstractZero‐order release of the physically dispersed active ingredients from the glassy hydrogels has been explained in the past on the basis of the case II transport of the penetrant medium into the matrix. This communication reports the zero‐order release of the pendent chain‐linked p‐nitrobenzoic acid from glassy as well as swollen hydrogel matrices. This has been explained on the basis of the time‐dependent diffusivity of p‐nitrobenzoic acid resulting from the structural changes in the matrix accompanying the release. p‐Nitrobenzoic acid would be released from these systems at a constant rate for periods of up to 5 months. Implants of this type in which the drug molecule is linked to the polymer backbone through the pendent chain are potentially promising systems for drug delivery at a constant rate for extended time periods.
Infrared spectra of raw and chemically modified pineapple leaf fiber (annanus comosus)
Authors: Saha S. C. , Das B. K. , Ray P. K. , Pandey S. N. , Goswami K. 
Published: April 2003

AbstractInfrared spectra of raw and chemically treated pineapple leaf fibers (PALF) have been studied using the KBr disk technique. Bands due to lignin and hemicellulose in the spectra of the fibers and their changes due to chemical (NaOH and NaCIO2) treatment have been discussed.
ESCA spectroscopy of poly(methyl methacrylate) grafted onto wood fibers
Authors: Kamdem D. P. , Riedl B. , Adnot A. , Kaliaguine S. 
Published: April 2003

AbstractThe incompatibility of hydrophilic wood fiber and hydrophobic polymers is the main difficulty with wood thermoplastic polymer composites. To overcome this issue, many researchers suggest grafting polymer onto wood fiber for improving the interfacial adhesion during mixing. A systematic ESCA study of chemi‐thermo‐mechanical pulp (CTMP) grafted fiber has been performed to provide chemical information about surface composition modification. The material analyzed included initial CTMP fiber, the pure polymer i.e., poly(methyl methacrylate) (PMMA) as reference material, and grafted fiber at different polymer loadings. Interest is focused on the carbon and oxygen spectra. Samples at high polymer loading or high grafting level have an O/C, C1, C2, C4, O1, and O2 intensities much similar to those of the PMMA but a little different since some wood fiber sites have still not fixed the polymer. ESCA spectra provide information on about 1–5 nm depth. The ESCA technique allows the monitoring of grafting polymer onto wood fiber as a surface phenomenon.
Copolymerization of turkish tall oil specimens with indene–coumarone. I. Studies on copolymerization of tall oil and indene–coumarone
Authors: Üstün Güldem , Civelekoǧlu Halidun 
Published: April 2003

AbstractIn this study copolymerization of Turkish tall oil specimens with technical grade indene–coumarone fraction of coal‐tar oils (bp 150–230°C) was investigated. The effects of temperature, the reaction time and reactant ratio on the reaction rate, and the composition of the resulting copolymer were determined. Based on these studies the optimal reaction conditions were established. Some main characteristics of these new type of tall oil/indene–coumarone copolymers determined were.
Properties of recycled high density polyethylene from milk bottles
Authors: Pattanakul C. , Selke S. , Lai C. , Miltz J. 
Published: April 2003

AbstractThe effect of virgin, high‐density polyethylene (HDPE)/recycled HDPE composition on the physical properties of the blends was investigated. The recycled HDPE was obtained from a postconsumer cycle of milk bottles. It was found that elongation at break was the mechanical property mostly affected by the content of recycled HDPE. Overall, however, the recycled HDPE from milk bottles was found to be a material with useful properties not largely different from those of virgin resin and thus could be used, at an appropriate concentration in virgin HDPE, for different applications.