bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structure–property relationships for styrene crosslinked polyesters. II. Glass transition temperature
Authors: Bellenger V. , Mortaigne B. , Verdu J. 
Published: April 2003

AbstractThe glass transition temperature of 10 styrene‐free polyester prepolymers and the corresponding networks crosslinked by about 40% by weight of styrene were determined by DSC (and by DMA in the case of networks).The glass transition temperature TgL of an hypothetical copolymer containing all the difunctional units of the network was then calculated. It is an increasing function of the molar weight of the prepolymer and of the phthalate/maleate molar ratio. From IR and NMR measurements, it was established that the structural irregularities other than polyester chain ends, especially unreacted double bonds, can be neglected to a first approximation. A constituent repeat unit (CRU) defined on the basis of these results allows the calculation of the crosslink density n. Then, various theories of the effect of n on Tg are compared. It appears that neither the Fox and Loshaek nor the Di Marzio approach gives good results. The crosslinking constants are lower than those found for aliphatic skeleton polyesters or epoxies. In the series under study, they display a tendency to decrease with the aromatic content. Some possible reasons of this peculiar behavior are discussed.
Functional polymers for colloidal applications. II. Hydrophobic effects of polyacrylic copolymer on dispersing polar and nonpolar particles
Authors: Kuo Ping‐Lin , Chang Ta‐Cheng 
Published: April 2003

AbstractThe polyacrylic acids with fixed molecular weights are specifically esterified by lauryl alcohol and methyl alcohol to prepare copolymers. These copolymers are used as dispersants for dispersing TiO2 and carbon black. It was found that lauryl‐esterified copolymers decrease the minimum viscosity and optimum concentrations both for TiO2 and carbon black due to strong hydrophobic interactions. However, the methyl esterified polyacrylic acid significantly broadens the range of optimum concentrations due to the interruption of polymer interactions between particles by methyl groups. Four different dispersion systems (LB/carbon black, LB/TiO2, MB/carbon black, and MB/TiO2) are used. These results are discussed and correlated to the structure of dispersant. The bridging effect of esterified lauryl group and the antibridging effect of esterified methyl group are used tó interpre the viscosity phenoma of those dispered systems.
Plasma polymerization of organoisothiocyanates. II. Structure of polymer film
Authors: Czeremuszkin G. , Wróbel A. M. , Kryszewski M. 
Published: April 2003

AbstractMethyl‐, n‐propyl‐, allyl‐, and phenyl isothiocyanates (MITC, PITC, AITC, and PHITC respectively) were polymerized in an RF (13.56 MHz) plasma electrodeless flow system. The plasma produced polymers were characterized using IR, GPC, GC/MS, and direct pyrolysis mass spectrometry (DPMS) techniques. The solubility tests and chromatographic examinations of the polymers revealed a small soluble fraction which contained a mixture of oligomers with a predominance of dimers and trimers. Molecular structure of the components of these fractions, identified by GC/MS, suggests fragmentation of the monomers to reactive fragments: \documentclass{article}\pagestyle{empty}\begin{document}$$ ^ \cdot {\rm RSCN},^ \cdot {\rm RCN},{\rm R}^ \cdot ,^ \cdot {\rm CN} $$\end{document} (in the case of MITC, PITC, AITC) and \documentclass{article}\pagestyle{empty}\begin{document}$ ^ \cdot {\rm ArNCS},{\rm PhS}^ \cdot ,{\rm Ph}^ \cdot ,^ \cdot {\rm CN} $\end{document} (in the case of PHITC). The DPMS data, being generally consistent with IR and GS/MS results, proved the presence in the polymers of sulfide, polysulfide, thiocarbonyl (–CS–S–and–S–CS–S–) groups, and molecular sulfur S8. Elementary plasma reactions involved in the formation of the observed structural units are proposed.
The enhancement of microvoids in acrylic fibers
Authors: Qin Jian 
Published: April 2003

AbstractThe present work is concerned with the spinning of two series of blend fibers containing acrylic copolymer(PAC) and small amount of secondary polymer, such as polyvinyl acetate (PVAc), polystyrene (PS), acrylonitrile‐styrene (AS) and acrylonitrile‐vinyl acetate (AVAc) copolymers. The blend acrylic fibers we developed have a microporous structure that renders them highly water retentive and confers several other excellent properties. Some factors were further studied that greatly influence the microporous volume and micropore size distribution, such as compatibility and phase separation of the polymer blends, the composition and sequence distribution of the secondary copolymers, and fiber formation conditions.
Melt viscosity and flow birefringence of polycarbonate
Authors: Nagai Tohru , Kimizuka Yuichi , Nito Keiichi , Seto Jun'Etsu 
Published: April 2003

AbstractMelt viscosity and flow birefringence of bisphenol A‐type polycarbonate were measured and analyzed by the application of rubber‐like photoelastic theory. The melt viscosity in the Newtonian flow region increased with the molecular weight to the power of 3.4. In polycarbonate, the shear stress of the Newtonian flow region was to 106 dyn/cm2, whereas in PMMA it was at most 3 = 105 dyn/cm2.The flow birefringence δn has a linear relation with shear stress S, that is δn = 5.7 × 10−10 S. The principal polarization difference of flow unit α1 – α2 was 1.62 × 10−23 cm3, which was obtained by the application of the rubber‐like elastic theory. In PMMA, it was 3.9 = 10−25 cm3; about 1/40 of that was polycarbonate. The anisotropy of polarizability of the flow unit of polycarbonate was also about 40 times larger than that of PMMA. So the anisotropy reflected the large flow birefringence of the polycarbonate.
Triazine networks modified with monofunctional reactive cyanate ester monomers
Authors: Papathomas K. I. , Wang D. W. 
Published: April 2003

AbstractThe preparation of cyanate ester thermosetting resins by coreacting a fluorinated bisphenol A dicyanate (6F‐BADCY) monomer with a monofunctional reactive cyanate, namely, the dinonyl phenol cyanate (DNPC), is described in this paper. Our objective in this study was to modify the 6F‐BADCY system with reactive diluents of a nonpolar nature and produce matrix resins processable at FR‐4 epoxylike conditions. By introducing the monofunctional cyanate as a reactive diluent, it is expected that the molar crosslink density of the resulting network will be reduced. Highly branched triazine polymers will result from this approach. Dinonyl phenol cyanate was quantitatively synthesized by reacting dinonyl phenol with cyanogen bromide in the presence of triethylamine.
Butadiene–styrene copolymerization initiated by n‐BuLi/THF/t‐AmOK
Authors: Lehong Bu , Shengkang Ying 
Published: April 2003

AbstractIn this article, the anionic copolymerization of butadiene and styrene initiated by n‐BuLi/THF/t‐AmOK in cyclohexane at 50°C has been studied in detail. The various ratios of the modifier (THF and t‐AmOK) to the initiator (n‐BuLi) influence the copolymerization rate and composition of copolymers.It has been shown that this polymerization system is a complex one in which there exist multiple active species. By adjusting the ratio of K to Li and the ratio of THF to Li, copolymers with compositions almost identical to the ratio of initial monomers at different stages of conversion have been obtained.The propagating regularity of various active species has been discussed qualitatively.
The microstructure of butadiene and styrene copolymers synthesized with n‐BuLi/THF/t‐AmOK
Authors: Lehong Bu , Shengkang Ying 
Published: April 2003

AbstractA study of the microstructure of copolymers, synthesized by B–S anionic copolymerization, initiated with n‐BuLi/THF/t‐AmOK in cyclohexane at 50°C, has been performed. Moreover, the mean sequence length in the B–S copolymer chain has been determined. The result showed that the microstructure of copolymers were sharply influenced by various ratios of modifier (THF, t‐AmOK) to initiator (n‐BuLi). By selecting a proper ratio of K/Li and THF/Li, B–S copolymers with unique randomness, having composition almost indentical to the initial monomer ratio at different stages of conversion and very low vinyl content, have been obtained.The formation mechanism of the copolymer chain structure is discussed.
Analytical characterization of weather‐degraded polyacrylonitrile fiber
Authors: Howell Huston E. , Patil Arvind S. 
Published: April 2003

AbstractPolyacrylonitrile (PAN) fiber was analytically characterized to identify the structural changes that occur due to atmospheric degradation. Degradation structures comprised of CC, CN, and CO species were identified using infrared spectroscopy. A significant decrease in the molecular weight was measured using size exclusion chromatography. PAN–acrylate copolymer fibers were analyzed and found to exhibit the same type of structures and changes in properties upon atmospheric degradation.
Infrared spectra of jute stick treated with white‐rot fungus
Authors: Roy A. K. , Bag S. C. , Basak M. K. , Sen S. K. 
Published: April 2003

AbstractJute stick was treated with white‐rot fungus for incubation periods of 6 days (MBA) and 12 days (MBB). The infrared spectra of fungus treated samples (MBA and MBB) and control jute stick (MBC) were analyzed and compared. The bands attributed mainly to hemicellulose show an increase in absorbance intensity ratios (Aν/A2900) with increase of incubation time. Similarly the bands attributed to lignin show an increase in the absorbance intensity ratios with increase of incubation time. Increase in the intensity of 1635 cm−1 band with increase of incubation time was also observed.
Determination of the fiber content in polymer composites by means of X‐ray absorption measurements
Authors: Schipp C. , Röber S. , Zachamann H. G. , Seferis J. C. 
Published: April 2003

AbstractThe X‐ray absorption coefficients of carbon fibers, different polymeric matrix materials, and composites were measured and the fiber contents in the composites were calculated from the measured absorption. In addition the fiber content determinations were performed by means of acid digestion of the polymeric matrix and weighing. Good agreement was found between the results obtained by the two different methods. The experimental error in the fiber content measurements was determined as a function of the difference in the coefficient of the matrix material and the fiber.
Polyester adhesion to chromium‐coated steel for poly(ethylene terepthalate) and an isophthalate copolymer
Authors: Yokoya Hirokazu , Porter Roger S. 
Published: April 2003

AbstractThe performance of PET [poly(ethylene terephthalate)] and a copolymer of PET has been tested as an adhesive for chromium‐coated steel. Crystallinity in the polyesters is found to limit adhesion, probably by restricting chain mobility. Lamination temperatures above the melting point of each polyester give the best adhesion. Degradation of the polyesters at yet higher temperature resulted in both reduced polymer cohesion and adhesion.Optimum bonding to steel was obtained at lamination temperatures between 230 and 275°C for the copolyester and between 280 and 300°C for PET. The standard laminate compression time was 15 min at 50 kg/cm2. Adhesion was evaluated by the ASTM T‐peel test. Assessments were made by both the peel energy and the peak load for peel.
Maleation of linear low‐density polyethylene by reactive processing
Authors: Gaylord Norman G. , Mehta Rajendra , Mohan Doraiswamy R. , Kumar Vijay 
Published: April 2003

AbstractThe reaction of maleic anhydride (MAH) with molten 2 MI poly(ethylene‐co‐butene‐1) (LLDPE) at 160°C in the presence of peroxyesters (t1/2 < 10 s) as catalysts resulted in the formation of a mixture of cross‐linked and trichlorobenzene‐soluble LLDPE‐g‐MAH. The soluble fraction constituted more than 50% of the mixture and had an MI of 0.0 and an MAH content ranging from 0.3 to 1.8 wt %. The presence of tri(nonylphenyl) phosphite (TNPP) in the LLDPE–MAH–t‐butyl peroctoate (tBPO) reaction at 160°C increased the MI of the soluble product to 0.7–2. The amount of soluble polymer increased at higher TNPP concentrations while its MAH content ranged from 0.05 to 0.54 wt %, with most contents in the 0.2–0.3 wt % range. The color development that usually occurs in polyolefin–MAH reactions was reduced by the presence of TNPP. However, the reaction of TNPP with the peroxide and from the thermal decomposition thereof reduced the availability of the excited species necessary for the appendage of MAH units onto the polyofin.
Transport properties of dichloromethane in glassy polymers. I. Atactic polystyrene films
Authors: Vittoria V. , Filho A. Ruvolo 
Published: April 2003

AbstractSorption and diffusion of dichloromethane vapor were measured in atactic polystyrene films, obtained with different cooling conditions and after controlled aging times at different temperatures. The diffusional behavior is characterized by three zones, depending on temperature and penetrant activity. In Zone I, at low activity, the diffusion coefficient is independent of vapor concentration; Zone II is characterized by concentration‐dependent diffusion, whereas in Zone III structural transformations are possible. The study of diffusion at three temperatures allowed building of a temperature‐penetrant concentration diagram, which is very useful to visualize the different zones of behavior. The aging at room temperature has no effect on the curve of sorption as a function of vapor activity, whereas it determines two effects on the diffusion: a decrease of the zero concentration diffusion coefficient and a more and more anomalous behavior with the aging time. The aging at 70°C produces the same effects on the diffusion behavior as the aging at room temperature; in addition, a decrease sorption is observed at low penetrant activity. The possible presence of ordered domains, impermeable to the vapor, in the samples stored at 70°C, was suggested on the basis of sorption results.
Extruded blends of a thermotropic liquid crystalline polymer with polyethylene terephthalate, polypropylene, and polyphenylene sulfide
Authors: Heino Markku T. , Seppälä Jukka V. 
Published: April 2003

AbstractStructure–property relationships were investigated for blends of a polyester‐type thermotropic liquid crystalline polymer (LCP) with polyethylene terephthalate (PET), polypropylene (PP), and polyphenylene sulfide (PPS). The polymers were melt blended in a twin‐screw extruder and the blends were extruded to strands of different draw ratios. Tensile properties of the blends were determined as a function of LCP content and draw ratio and compared with the results of morphological and rheological analyses. In general, the strength and stiffness of the matrix polymers were improved with increasing LCP content and draw ratio. At a draw ratio of 11, the blends of PET/30 wt % LCP exhibited a tensile strength about three times and an elastic modulus nearly four times that of pure PET. All blends exhibited a skin/core morphology with thin fibrils in the skin region. The formation and the sizes of the fibril‐like LCP domains in the matrices were found to depend on LCP content and the viscosity ratio of the blend components.
Structural changes in draw‐textured poly(ethylene terephthalate) filaments during heat‐setting
Authors: Bechev C. D. , Mishinev J. T. 
Published: April 2003

AbstractA sample of high‐elastic‐textured poly(ethylene terephthalate) (PET) yarns were subjected to different conditions of heat‐setting, i.e., different temperatures and overfeeds. The structural changes were characterized by different physical methods. The orientation factors of crystalline and amorphous regions were calculated. The yarn tensions acting during the SET process were measured and corrected to the structural data. The results obtained show that two processes take place during the SET process: relaxation of the molecule segments in amorphous regions and change of crystallite orientation in microfibrils. A simple model for explanation of the structural changes in simultaneously draw‐textured PET yarns is proposed.
On the graft polymerization of styrene and acrylonitrile onto polybutadiene in the presence of vinyl acetate. II. Properties of graft polymers
Authors: Schellenberg Jürgen , Hamann Bernd 
Published: April 2003

AbstractThe properties of the graft polymers of styrene, acrylonitrile, and vinyl acetate onto polybutadiene rubber that were prepared for the modification of graft polymers of styrene and acrylonitrile onto polybutadiene (ABS polymers) by emulsion polymerization up to a high degree of conversion have been studied and discussed. Both the impact strength and notched impact strength of the graft polymers have been found to remarkably increase with a rising quantity of vinyl acetate, in particular, in the case of styrene substitution, whereas in the case of acrylonitrile substitution by vinyl acetate, the two characteristics become noticeably poorer. The effects of the vinyl acetate amount and the type of substituted monomers on bending strength, tensile strength, Vicat softening point, and glass transition temperature of the graft polymers are also clearly different. Furthermore, the properties of the above graft polymers blended with styrene/acrylonitrile copolymers have been studied.
Triallylphosphine plasma polymerization and reaction of the product with volatile transition metal compounds
Authors: Clymer S. D. , Morosoff N. C. , Crumbliss A. L. 
Published: April 2003

AbstractThe plasma polymerization of triallylphosphine in order to form a crosslinked polymer thin film is described. The plasma polymer thin film has been characterized and shown to contain a high proporation of CC and P groups conserved from the monomer. The accessibilty of the phosphine groups has been demonstrated by reaction with O2, NO, Ni(CO)4, and Fe(CO)5. Reaction with O2, and NO results in a PO moiety formation. Reaction with the gaseous metal carbonyls results in fixation of the metal via complexation by the P groups as a result of exchange with CO ligand(s). This illustrates the utility of a ligand donor group containing plasma polymer as an avenue for the formation of a single phase transition metal containing plasma polymer.
Correlations involving modulae and cross‐polarization time constants for a series of polyurethane elastomers
Authors: Marcinko J. J. , Parker A. A. , Shieh Y. T. , Ritchey W. M. 
Published: April 2003

AbstractCorrelations between the macroscopic bulk polymer properties storage modulus (E′) and loss modulus (E″) and the microscopic property of cross‐polarization as represented by the time constant TCH have been established for a series of polyurethane elastomers. The dependence of E′, E″, and TCH as a function of molecular weight, rigid domain concentration, and temperature are graphically presented as a series of log plots. An experimental relationship is presented that shows that the distribution of motions of the flexible domains appears to be the major factor in the success of these correlations.
Synthesis and properties of an easy‐processable bismaleimide thermoset resin
Authors: Winter H. , Mostert H. A. M. , Tholen M. G. W. 
Published: April 2003

AbstractReaction of methylenedianiline and maleic anhydride in acetone, followed by cyclodehydration in the presence of acetic anhydride and 1,4‐diazabicyclo [2.2.2] octane as a catalyst, affords a mixture of compounds, Desbimid, with maleimide, isomaleimide, and acetamide groups. Dissolution of this mixture in styrene and 2‐hydroxyethyl methacrylate results in clear liquid resins. The viscosity of the formulated resins ranges from 100–1700 mPas at 25°C depending on the concentration of Desbimid. These systems can be processed and cured at ambient temperatures until demoulding and postcured at temperatures up to 200 or 250°C. The flexural modulus, flexural strength, and elongation at break of a number of cured formulations are found between 3500–3800 N/mm2, 90–115 N/mm2, and 2.7–3.5%, respectively.
Preparation of epoxy‐terminated poly(aryl ether sulfone)s and their use as modifiers for epoxy resins
Authors: Iijima T. , Hiraoka H. , Tomoi M. 
Published: April 2003

AbstractEpoxy‐terminated poly(aryl ether sulfone)s (PSE) were prepared by the reaction of epichlorohydrin with hydroxyethyl‐terminated polysulfones, which were synthesized from chloro‐terminated polysulfones (PSC) and diethanolamine. Both PSE and PSC were used as modifiers for toughening of bisphenol A diglycidyl ether epoxy resin cured with p,p′‐diaminodiphenyl sulfone. The mechanical, thermal, and dynamic viscoelastic properties of the modified resins were examined and compared to the parent epoxy resin. The effectiveness of PSC was larger than that of PSE. The fracture toughness, KIC, for the modified resin increased 45% at slight expense of its mechanical properties on 20 wt % addition of PSC (Mw 5300). These results were discussed in terms of the morphological and dynamic viscoelastic behaviors of the modified epoxy resin system.
Synthesis of highly conducting nylon‐6 composites and their electrical properties
Authors: Park Yun Heum , Choi Sang Hoon , Song Suk Kyu , Miyata Seijo 
Published: April 2003

AbstractHighly conducting nylon‐6 composites are synthesized by exposing nylon‐6 films or fabrics impregnated with an oxidizing agent, cupric chloride, simultaneously to aniline and hydrochloric acid vapors. The conductivity of composite films reaches up to 10−2 S/cm and can be controlled by varying the experimental conditions for the composite synthesis. The effects of the concentration of cupric chloride, exposure time to aniline and hydrochloric acid vapors, and concentration of hydrochloric acid to the polyaniline content and the conductivity of nylon‐6/polyaniline composites are analyzed by means of statistical F test. The morphology change of composite films resulting from the synthesis conditions, conductivity in relation to the morphology, and stability of conductivity to ambient air exposure have been investigated.
Prediction of vibration damping properties of polymer‐laminated steel sheet using time–temperature superposition principle
Authors: Liao Fu‐Sen , Hsu Tzu‐Chien J. 
Published: April 2003

AbstractThe vibration damping properties of the polymer‐laminated steel sheet have been investigated theoretically and experimentally. The laminate consisted of a polymer layer, which was sandwiched between two steel sheets. Two polymers a polyvinyl butyral and a copolymer of ethylene and acrylic acid, were used. The theoretical analysis was based on a model proposed by Ungar. A frequency analyzer was used to measure the loss factor of the laminate. The model required rheological data, such as storage modulus G′ and loss tangent of the polymer at high frequency, which could not be obtained from commercially available dynamic rheometers. The time–temperature superposition principle was applied to the laminated polymer to construct the master curves of G′ and loss tangent vs. frequency. These master curves provided rheological data at high frequency, which were superposed from data measured at low temperature. The results showed that a discrepancy existed between the loss factors predicted with superposed and without superposed data and the reasons for this discrepancy were discussed. The measured loss factors of the laminates at high frequency followed the predictions using superposed data, but not for those measured at low frequency. Factors accounting for this deviation were analyzed. The results also indicated that, in general, the transition temperature of the polymer‐laminated steel sheet was 15°C–30°C higher than the corresponding glass transition temperature of the laminated polymer.