bluuebunny/crossref_metadata_2025_split huggingface dataset:
Carbon‐13 NMR investigation of spin‐lattice relaxation mechanism of poly(4‐methyl‐1‐pentene)
Authors: Ma Sun , Chen M.‐C. , Wang S.‐P. 
Published: April 2003

AbstractCarbon‐13 spin‐lattice relaxation rates (1/T1) and nuclear Overhauser enhancement (NOE) measurements were performed on poly(4‐methyl‐1‐pentene) above the glass transition temperature in order to explain the segmental motion of the molecule by means of high resolution nuclear magnetic resonance spectroscopy. Experiments were carried out for poly(4‐methyl‐1‐pentene) with low, medium, and high molecular weights. The similarity of the T1 values showed that for polymers with a degree of polymerization (DP) > 100 the relaxation behavior of the carbon atoms no longer depends on molecular weight. The temperature effects were studied at 358, 363, 373, 383, 393, and 403 K, both on 25.18 and 100.61 MHz magnetic fields. Finally, several mathematical T1 models were applied to study the change of T1 encountered by the individual carbon atoms. The results reveal that the more factors being considered in the calculation the more consistent will be the results obtained with the T1 model. A comparison showed that parameters used in the DLM T1 model gives the best fit. © 1994 John Wiley & Sons, Inc.
Thermal behavior of p‐acryloyloxy‐tri‐n‐butyltin benzoate–acrylonitrile copolymers
Authors: Azab M. M. 
Published: April 2003

AbstractThe copolymerization of p‐acryloyloxy‐tri‐n‐butyltin benzoate (ABTB) with acrylonitrile (AN) has been investigated in dimethylformamide (DMF), using azobisisobutyronitrile (AIBN) as an initiator. The prepared homopolymer of (ABTB), as well as the copolymers, were characterized by a variety of analytical, spectral, and thermal methods. Thermogravimetry (TG) and differential thermal analysis (DTA) data showed a little improvement in the thermal behavior of the investigated copolymer. A mechanism for the initiation of ABTB units in the nitrile oligomerization in the copolymer was also proposed. © 1994 John Wiley & Sons, Inc.
Adhesive monomers to dental ceramics. II. Methacrylamide derivatives containing carboxyl and phenyl groups for effective adhesion of calcium metaphosphate ceramic
Authors: Kitoh Shinya , Suzuki Kunitomo , Kiyohara Takao , Kurita Keisuke 
Published: April 2003

AbstractTwelve methacrylamide derivatives containing carboxyl and phenyl groups have been evaluated as adhesives for calcium metaphosphate ceramic, a promising but hard‐to‐adhere cast ceramic restoration material. Although methacrylamide monomers having a carboxyl group showed low adhesive tensile strength for the ceramic, contrary to the glycidyl methacrylate derivatives, the monomer having neighboring two carboxyl groups at the phenyl ring exhibited quite high adhesion. Moreover, the monomer proved to retain high adhesion strength for the surface‐etched ceramic for a long period of time even in water and would thus be suitable for practical clinical applications. © 1994 John Wiley & Sons, Inc.
Preparation of superconducting edge junctions using polymeric Langmuir–Blodgett films as barrier layers
Authors: Liu Yun Qi , Zhang Jin Biao , Wu Pei Ji , Zhu Dao Ben , Sun Zhi Jian , Ji Zheng Ming , Yang Sen Zu , Wu Pei Heng 
Published: April 2003

AbstractAromatic polyamic acid alkyl ammonium salt exhibits very good transfer behavior under suitable deposition conditions. A superconducting thin film of YBa2Cu3Ox (YBCO) on Langmuir–Blodgett film (LB) has been obtained when the substrate temperature is higher than 500°C. Superconducting edge junctions of (Pb—In)/LB/(Pb—In) and YBCO/LB/YBCO incorporated with polyimide LB films were fabricated. Their current–voltage characteristics are discussed in terms of the temperature stability of polyimde LB films. © 1994 John Wiley & Sons, Inc.
Microstructure of charged mosaic membranes constructed by phase growth
Authors: Ishizu Koji , Iwade Masaya 
Published: April 2003

AbstractA template pattern with alternating poly(4‐vinylpyridine) (P4VP)/poly(vinyl alcohol) (PVA) lamellae was fabricated upon a cross‐linked PVA film by casting of poly[4‐vinyl‐pyridine (4VP)‐g‐vinyl alcohol (VA)] graft copolymer. After a treatment involving the binding of a PVA film with the graft copolymer and also domain fixing of the PVA phases, a dilute solution of poly[acrylic acid (AA)‐benzyl N,N‐dimethyldithiocarbamate (DMTC)] copolymer/P4VP binary blend was cast on this template surface. The microstructure of binary blend was observed from scanning electron microscopy (SEM) by wet‐etching of films after domain fixing of one component of the binary blend. The poly(AA‐DMTC) copolymer/P4VP binary microdomains formed by phase growth were oriented perpendicularly to the film surface. We also fabricated these charged mosaic regions on a microporous poly(vinyl chloride) (PVC) membrane, and carried out the surface analysis by X‐ray photoelectron microscopy (XPS). Finally, we examined the transport of KCl through the charged mosaic composite membranes. © 1994 John Wiley & Sons, Inc.
Studies on the sulfonation of poly(phenylene oxide) (PPO) and permeation behavior of gases and water vapor through sulfonated PPO membranes. III. Sorption behavior of water vapor in PPO and sulfonated PPO membranes
Authors: Jia L. , Fu H. , Xu J. , Hirai A. , Odani H. 
Published: April 2003

AbstractWater vapor absorption and desorption by poly(phenylene oxide) (PPO) and sulfonated PPO (SPPO) membranes were studied at a constant temperature of 30°C and over a broad range of water activity (0.05 ≤ a < 0.8) by the weighing method. The experimental sorption isotherms of both PPO and SPPO possessed a general sigmoidal shape, which suggested that they belong to type II; thus, the data may be quantitatively analyzed according to the BET or GAB equation for multilayer sorption processes. The number of site‐bound water molecules per monomeric unit was increased by a factor of 150 after sulfonation of PPO. The features of the reduced absorption and desorption curves of both PPO and SPPO suggested that the sorption processes were non‐Fickian. The diffusion coefficient calculated from the slope of the initial linear part of the curves showed concentration dependence. The permeability of water vapor through SPPO was more pressure‐dependent than was that through PPO. The Flory–Huggins interaction parameter derived from experimental data on SPPO had a smaller value compared with that of PPO and was a monotonic increasing function of water activity in the low‐activity region and then leveled off at a > 0.6, showing a corresponding initial decrease of the polymer–water interaction, which then gradually reached a certain stable value. Water clustering for SPPO was much less than that for PPO, which is clear proof of its higher hydrophilicity. The results from this study showed that SPPO could be an excellent dehumidification membrane material. © 1994 John Wiley & Sons, Inc.
Deformation of rubber‐toughened polycarbonate: Macroscale analysis of the damage zone
Authors: Cheng Chihmin , Hiltner A. , Baer E. , Soskey P. R. , Mylonakis S. G. 
Published: April 2003

AbstractTwo commercial core‐shell rubbers were used as impact modifiers for polycarbonate (PC). Specimens with a single semicircular edge notch were stretched uniaxially in order to study the prefracture damage evolution of blends under a triaxial tensile stress state. The irreversible deformation of modified PC included a cavitation mechanism in addition to the three shear modes of unmodified PC. At the macroscopic level, the cavitation condition could be described by a mean stress concept. The corresponding critical volume strain for cavitation in PC blends was determined to be independent of rubber content but differed for the two impact modifiers. The critical volume strain for cavitation was used as an index of cavitation resistance for the impact modifiers. The effect of rubber content and temperature on Izod impact strength of the PC blends was also reported. From the relationship between the cavitation resistance and the Izod impact strength, it was proposed that impact modifiers with a higher cavitation resistance impart better toughness to blends with PC. © 1994 John Wiley & Sons, Inc.
Fractography and failure mechanisms of particulate‐filled thermoplastic polyester
Authors: Li J. X. , Hiltner A. , Baer E. 
Published: April 2003

AbstractFractography has been used for the postfailure analysis of a filled thermoplastic polyester. The five fracture modes that were previously defined on the basis of macroscopic stress–strain behavior were distinguished by certain fractrographic features. These features were characteristic of the fracture mode and did not depend on filler type or filler content. The Mode A ductile fracture surface consisted of two regions: a pullout region of slower crack growth and a rosette region of faster crack growth. The Mode B ductile fracture surface contained only a ductile pull out texture. The Mode C quasi‐brittle fracture surface exhibited secondary fracture features that sometimes included the herringbone pattern. The Mode D quasi‐brittle fracture surface consisted of a stress‐whitened dimple region and a brittle fracture region. The Mode E Fracture surface exhibited primarily the rough texture characteristic of brittle fracture. The failure mechanisms inferred from analysis of the fracture surfaces confirmed a microscopic failure model of the ductile‐to‐quasi‐brittle transition in filled PETG that is based on the strain‐hardening strength of the polymer ligaments between debonded filler particles. © 1994 John Wiley & Sons, Inc.
PVC/MBS blends with small concentrations of PET: Failure processes in thin films during uniaxial tension
Authors: Li J. X. , Twigg M. V. , Hiltner A. , Baer E. 
Published: April 2003

AbstractThe effects of small concentrations of poly(ethylene terephthalate) (PET) particles on the failure of poly(vinyl chloride), blended with a (methacrylate–butadiene–styrene) impact modifier (PVC/MBS) were studied. The failure processes arising from isolated and interacting particles were observed in situ in the optical microscope during tensile deformation. At low PET content ( < 0.5%), voids grew around individual particles without particle‐particle interaction. Subsequently, a stable neck developed, and the material experienced relatively large deformation before fracture. With increasing PET content and increasing particle size, particle–particle interactions were observed. At higher PET content (≥ 1%), the neck was not stable and fracture occurred during neck formation. Materials with larger particles exhibited neck instability and fracture at lower PET content. © 1994 John Wiley & Sons, Inc.
Application of scanning acoustic microscopy to polymeric materials
Authors: Lisy F. , Hiltner A. , Baer E. , Katz J. L. , Meunier A. 
Published: April 2003

AbstractScanning acounstic microscopy (SAM) is now a viable technique for the nondestructive evaluation of various materials. SAM is capable of distinguishing defect and discontinuities and/or the variations in elastic properties on a scale comparable to optical microscopy. The pulse mode utilizes a single narrow acoustic wave that permits surface and internal studies over a range of frequencies from 5 to 200 MHz with resolution down to approximately 20 μm. This technique was applied to image surface features of an opaque sheet‐molding compound and to analyze flow patterns of chopped glass fibers. The pulse mode was also used to image the internal damage sustained from a high‐speed projectile in oriented polypropylene and two carbon fiber‐reinforced composites, with different matrices. Most importantly, the pulse mode of the acoustic microscope is a nondestructive method and the interior of samples that are entirely opaque can be readily studied with this unique instrument. The burst mode is composed of a group of acoustic waves and is capable of operating at higher frequencies than the pulse mode up to several gigahertz. This mode permits resolution down to the micrometer level and is especially useful for investigating surface and subsurface microstructural features. The burst mode was used to determine the distribution of chopped fibers in a PEEK matrix and carbon black particulars in an adhesive, the orientation of the mineral phase and density variations in a single osteon from a dog femur, and the orientation of collagen fibers in sheep meniscus. Also, the sensitivity of the burst mode to surface features was used to examine the topographical features in a multilayer composite and a blend of poly(vinyl chloride) (PVC) with poly(ethylene terephthalate) (PET) particulates. © 1994 John Wiley & Sons, Inc.
Effects of water content on the properties of starch/poly(ethylene–vinyl alcohol) blends
Authors: Dell Paul A. , Kohlman William G. 
Published: April 2003

AbstractThe physical properties of unmodified starch, poly(ethylene vinyl alcohol), glycerol, and water mixtures are reported. Thermal and melt‐flow properties of the preprocessed, physically mixed materials were determined along with the tensile properties and morphology of injection‐molded microtensile samples. Melt‐flow properties were measured by a capillary rheometer, and the water content was varied from 4 to 18%. The morphology, rheology, and tensile properties are all highly related to the percentage of water present. A transition in the tensile properties and morphology of the blends was observed at approximately 11% moisture content. © 1994 John Wiley & Sons, Inc.This article is a US Government work and, as such, is in the public domain in the United States of America.
Grafting poly(vinyl amine‐co‐acrylic acid)s on poly(vinylidene fluoride) membranes
Authors: Iwata Hiroo 
Published: April 2003

AbstractIn this study, N‐vinylacetamide (NVA) was graft‐polymerized and graft‐copolymerized with acrylamide (AAm) onto plasma‐activated surfaces. The polymer compositions of the grafted layer were estimated from X‐ray photoelectron spectroscopy spectra. N‐vinylacetamide was enriched in the grafted polymers in all regions of the monomer compositions. The primary amine groups could be densely introduced on the surface by hydrolyzing the grafted poly(vinylacetamide‐co‐acrylamide). © 1994 John Wiley & Sons, Inc.
Solvent replacement in the synthesis of persubstituted phosphonitrilic hydroquinone prepolymer materials
Authors: Femec Douglas A. , McCaffrey Robert R. 
Published: April 2003

AbstractA desirable solvent replacement has been effected in the synthesis of persubstituted phosphonitrilic hydroquinone prepolymer materials. The replacement of carbon tetrachloride with cyclohexane has no adverse effect on the composition and quality of the material prepared. The overall yield of the reaction increases from 65 to 70% and the toxicity of the reaction mixture and of the waste generated from the reaction are greatly reduced. The particularly close match of solvent properties between carbon tetrachloride and cyclohexane makes this an excellent solvent replacement. Such changes to less‐expensive, less‐toxic, and less‐environmentally damaging solvents are on the increase. A brief list of some known replacement solvents for use in polymer and coatings applications is presented. © 1994 John Wiley & Sons, Inc.This article is a US Government work and, as such, is in the public domain in the United States of America.
Mechanical properties of cellulose acetate propionate/aliphatic polyester blends
Authors: White Alan W. , Buschanan Charles M. , Pearcy Barry G. , Wood Matthew D. 
Published: April 2003

AbstractUseful blends of cellulose esters with other higher molecular weight polymers are generally unknown. Two aliphatic polyesters, poly(tetramethylene glutarate) (PTG) and poly(tetramethylene succinate) (PTS), have been thermally compounded with cellulose acetate propionate (CAP) in the range of 10–40 wt % polyester. These blends have been injection molded, and the mechanical properties of the molded bars were compared to bars molded from CAP plasticized with a low molecular weight diester, dioctyl adipate (DOA). The CAP/aliphatic polyester blends have significantly higher tensile strengths, flexural moduli, heat deflection temperatures, and greater hardness values than the corresponding CAP/DOA blends. © 1994 John Wiley & Sons, Inc.
Characterization of model anaerobic adhesive cure using real‐time fourier transform infrared spectroscopy and dielectric spectroscopy
Authors: McGettrick Brendan P. , Vij Jagdish K. , McArdle Ciaran B. 
Published: April 2003

AbstractA technique has been developed based on Fourier transform infrared spectroscopy (FTIR) in the attenuated total reflectance (ATR) mode, which is suitable for the investigation of the heterogeneous cure of surface‐initiated redox polymerizations in thin and thick bondline situations. The results of the investigations into the surface‐catalyzed and anaerobically promoted cure of some model adhesives using this method are reported. The systems under investigation were designed to exhibit different levels of cure heterogeneity or “cure through volume” (CTV) so that the influence of the bondline thickness and the formulation variables may be assessed. The analysis of the data provides evidence that supports our concept of the heterogeneous cure distribution existing in the form of a cure gradient. This concept of a cure gradient is developed further using dielectric spectroscopy. Here the cure gradient is characterized in terms of the parameters obtained using an empirical equation to fit the dielectric relaxation data. The results obtained using the infrared and dielectric spectroscopic methods are in satisfactory agreement and are shown to be most informative in characterizing and quantifying the CTV performance of the model anaerobic adhesives. © 1994 John Wiley & Sons, Inc.
Crystallization of poly(ethylene terephthalate) (PET) from the oriented mesomorphic form
Authors: Parravicini Lidia , Leone Biagio , Auriemma Finizia , Guerra Gaetano , Petraccone Vittorio , Di Dino Gabriele , Bianchi Riccardo , Vosa Renato 
Published: April 2003

AbstractYarns of different inherent viscosities, in the range 0.6–1.1 dL/g, spun in industrial plants, and drawn at room temperature to obtain mesomorphic samples, have been characterized. The evolution from the mesomorphic form toward the triclinic crystalline form has also been studied by combined differential scanning calorimetry (DSC), dynamic mechanical analyses (DMA), and accurate wide angle X‐ray diffraction experiments. The DMA analysis of the mesomorphic samples allows better resolution of the glass transition and crystallization phenomena, which are superimposed in the DSC scans. The degree of molecular orientation in the mesomorphic samples, and the temperature of crystallization from the mesomorphic form (60–80°C), are essentially independent of the polymer molar mass. © 1994 John Wiley & Sons, Inc.
Chain transfer behavior of fractionated commercial mercaptans in emulsion polymerization of styrene
Authors: Harelle Ludovic , Pith Tha , Hu Guo‐Hua , Lambla Morand 
Published: April 2003

AbstractThe chain transfer behavior of fractionated commercial tertiary mercaptans was investigated in batch and semicontinuous emulsion polymerization of styrene over the entire monomer conversion range. Four mercaptans were obtained by fractionation, which contained 9, 11, 12, and 13 carbons, respectively. The effect of the mercaptans was evaluated in terms of the consumption rates of the monomer and the chain transfer agents, the number average degree of polymerization, DPn, and the polydispersity index, I, of the polymer. The batch experiments showed that the chain transfer efficiency decreases with increasing carbon number, which is due primarily to a lower diffusion rate of the chain transfer agent to the reaction sites (growing latex particles) through the aqueous phase. The partitioning ratio of the chain transfer agents between the aqueous phase and the monomer droplets also contributes, to a lesser extent, to the efficiency. The number average degree of polymerization and the polydispersity index are primarily controlled by the ratio of the mercaptan consumption rate over that of the monomer. In order to obtain a polymer with a constant DPn and a narrow I, this ratio should be as close to unity as possible, as is the case for C11. Otherwise, too high a ratio causes a severe increase in DPn at the end of polymerization, and too low a ratio leads in the opposite direction. The semicontinuous experiments confirmed the batch results. © 1994 John Wiley & Sons, Inc.
Phosphorus modification of epoxidized liquid natural rubber to improve flame resistance of vulcanized rubbers
Authors: Derouet D. , Radhakrishnan N. , Brosse J.‐C. , Boccaccio G. 
Published: April 2003

AbstractThe use of phosphorus for improving flame retardancy of natural rubber vulcanizates was attempted by incorporating a modified form of natural rubber. By reacting epoxidized liquid natural rubber (ELNR) with dibutylphosphate it was possible to chemically modify the polymer. On a 25% epoxidized LNR, 5.2–6.8% w/w of phosphorus could be fixed on the polymer backbone. The reaction carried out in bulk and solution resulted in products with different Tg values probably due to the varying crosslink levels in the resultant products. Chemical analysis of the modified polymers prepared by two sets of reactions under identical conditions proved the reproducibility of the reactions in bulk and in solution. Incorporation of the phosphorus‐modified ELNR in a natural rubber formulation decreased the flammability behaviors of the vulcanizate. On the other hand, a decrease of the rate of curing and mechanical properties was observed. The phosphorus addition could also be carried out by mixing ELNR and dibutylphosphate at the time of mixing the compounds and resulted in equally good flame retardance with relatively better processing and mechanical properties. © 1994 John Wiley & Sons, Inc.
Comparative study on rebound resilience and structures of sodium salts of maleic anhydride‐grafted ethylene‐co‐ethyl acrylates with its analogous polymers
Authors: Iwase Yoshiyuki , Hara Hisaaki , Hirasawa Eisaku 
Published: April 2003

AbstractSodium salts of ethylene‐co‐ethyl acrylate‐g‐maleic anhydride show high rebound resilience, the same as those of both saponified ethylene‐co‐ethyl acrylates and sodium salts of ethylene‐co‐methacrylic acids at low salt contents. The measurements of thermal and mechanical properties and dynamic viscoelastic behaviors indicate that the sodium salts of ethylene‐co‐ethyl acrylate‐g‐maleic anhydride behave like strong ionic bond cross‐linkages close to covalent bond cross‐linkages in the polymer, differing from the monocarboxylate salts of saponified ethylene‐co‐ethyl acrylate and the sodium salts of ethylene–methacrylic acid. It is concluded that the strong cross‐linking of the dicarboxylate salts of the neutralized ethylene‐co‐ethyl acrylate‐g‐maleic anhydride causes the high rebound resilience. © 1994 John Wiley & Sons, Inc.