bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of high‐strength fibers from aliphatic polyketones by melt spinning and drawing
Authors: Gupta P. , Schulte J. T. , Flood J. E. , Spruiell J. E. 
Published: October 2004

AbstractWe have investigated the formation of high‐strength, high‐modulus fibers from four aliphatic polyketone resins. One resin was a perfectly alternating copolymer of ethylene and carbon monoxide, while the other three were terpolymers containing up to 6 mol % propylene. The mechanical properties were measured as a function of processing conditions, and the structures of the filaments were characterized using birefringence, WAXS, SAXS, SEM, and thermal analysis. Fibers formed from all resins develop very high molecular orientations and a microfibrillar structure. Fibers having room temperature tenacities as high as 10 gpd (∼1.1 GPa) were obtained. Tensile moduli reached values as high as 120 gpd (∼13 GPa). The melting point of the fibers was primarily dependent on the composition of the resin, while the maximum strength and modulus were largely determined by the maximum draw ratio achieved. The maximum draw ratio achieved in the present experiments was greater for the terpolymers than for the copolymer. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1794–1815, 2001
Proton nuclear magnetic resonance spectroscopic analysis of polypeptide models of the elastic network phase of wool fibers: Defining Cys‐residues capable of serving as a crosslinking agent
Authors: Liff Mark I. 
Published: October 2004

AbstractA polymer network structure of the matrix phase of wool fibers was modeled by polypeptide systems containing fragments of high sulfur (HS) proteins with Cys‐residues oxidized in pairs to form a network. Our previous studies have shown that Cys‐residues belonging to the two characteristic repeats (dipeptide and pentapeptide) from HS proteins of the matrix have a low propensity to serve as crosslinks of the matrix. This study reveals that Cys‐residues located outside the two repeats have a higher propensity to serve as crosslinks of the network than Cys‐residues belonging to the repeats. Effective crosslinking by the nonrepeat Cys‐residues, on the one hand, and formation of intrarepeat loops by the residues of the repeats, on the other hand, can explain well‐known macroscopic properties of the matrix phase, such as its elasticity and ability to swell in solvents. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1824–1828, 2001
Replacement of virgin rubbers by waste ground vulcanizates in blends of silicone rubber and fluororubber based on tetrafluoroethylene/propylene/vinylidene fluoride terpolymer
Authors: Ghosh Arun , Antony P. , Bhattacharya A. K. , Bhowmick A. K. , De S. K. 
Published: October 2004

AbstractThis study reports the results of investigations on blends of silicone rubber and fluororubber based on tetrafluoroethylene/propylene/vinylidene fluoride terpolymer and the effects of replacement of silicone rubber and/or fluororubber in their 50/50 blend by the respective vulcanizate powders of known compositions. To simulate the aging condition of factory wastes, the silicone rubber or fluororubber vulcanizates were aged for 72 h at 200°C and then converted into powder by mechanical grinding. The fluororubber vulcanizate powder (FVP), mostly spherical in shape with average diameter varying between 2 and 10 μm, exists in a highly aggregated state displaying chainlike structures that, however, break down during blending with virgin rubbers. The silicone rubber vulcanizate powder (SVP) is irregular in shape, with larger particles in the range of 30–100 μm, and the smaller particles exist in highly aggregated chainlike structures, as in the case of FVP, which break down during milling to mostly spherical particles of 2–10 μm in diameter. Measurements of physical properties reveal that the blends of silicone rubber and fluororubber are technologically compatible. SEM photomicrographs of THF‐etched samples show the biphasic structure of the blends, in which the fluororubber forms the dispersed phase in a continuous silicone rubber matrix of lower viscosity. Replacement of silicone rubber in the 50/50 silicone rubber/fluororubber blend by its vulcanizate powder (SVP) increases the Mooney viscosity, but replacement of fluororubber in the blend by its vulcanizate powder (FVP) has little effect on the Mooney viscosity. Monsanto rheometric studies reveal that replacement of silicone rubber by SVP or fluororubber by FVP in the 50/50 silicone rubber/fluororubber blend increases the minimum rheometric torque but decreases the maximum torque, and the effect is more pronounced in the case of SVP. Furthermore, the replacement of silicone rubber in the blend by SVP causes a decline in the physical properties (25% replacement causing about 10% decline in properties, for example), whereas even 75% replacement of fluororubber by FVP has little effect on the physical properties. When both silicone rubber and fluororubber are partially replaced by SVP and FVP in the same blend, properties of the resulting blend composition are controlled more by SVP incorporation, whereas fluororubber replacement has only a marginal effect on blend properties. It is evident from dynamic mechanical spectra that the blends are immiscible in all compositions and addition of SVP or FVP does not affect the glass–rubber transitions of the constituent polymers. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2326–2341, 2001
Synthesis and characterization of novel biodegradable polymers composed of hydroxycinnamic acid and D,L‐lactic acid
Authors: Matsusaki Michiya , Kishida Akio , Stainton Neil , Ansell Christopher W. G. , Akashi Mitsuru 
Published: October 2004

AbstractD,L‐Lactic acid (DLLA) was polycondensed with 4‐hydroxycinnamic acid (4HCA), a derivative of cinnamic acid, to prepare a novel functional biodegradable polymer. The polymer was prepared using two different methods, the solvent method, which used acetic anhydride as the solvent, and the direct method. White and brown‐colored copolymers were obtained by these two methods, respectively. 1H‐NMR spectroscopy and UV‐visible spectroscopy revealed that the double bond of 4HCA was almost completely destroyed when the copolymer was prepared by the direct method. On the other hand, copolymers in which the double bond was preserved in the 4HCA–DLLA copolymer were successfully obtained using the solvent method. The solubility of the copolymers obtained by the solvent method in organic solvent was poor. When the copolymer was prepared under a 4HCA:DLLA ratio of 20:80 using the solvent method, the resulting copolymer had high solubility in organic solvents and the double bond was preserved. Moreover, it was confirmed that the 4HCA–DLLA copolymer synthesized by the solvent method was both photoreactive and biodegradable. The 4HCA–DLLA copolymer is expected to be used as basic material for tissue engineering and drug delivery systems, in addition to applications as an orthopedic matrix and a degradable plastic. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2357–2364, 2001
In situ compatibilization of polystyrene and polyurethane blends by using poly(styrene‐co‐maleic anhydride) as reactive compatibilizer
Authors: Cassu Silvana Navarro , Felisberti Maria Isabel 
Published: October 2004

AbstractBlends of polystyrene (PS) and polyurethane (PU) elastomer were obtained by melt mixing, using poly(styrene‐co‐maleic anhydride) (SMA) containing 7 wt % of maleic anhydride groups as a reactive compatibilizer. Polyurethanes containing polyester flexible segments, PU‐es, and polyether flexible segments, PU‐et, were used. These polyurethanes were crosslinked with dicumyl peroxide or sulfur to improve their mechanical properties. The anhydride groups of SMA can react with the PU groups and form an in situ graft copolymer at the interface of the blends during their preparation. The rheological behavior was accompanied by torque versus time curves and an increase in the torque during the melt mixing was observed for all the reactive blends, indicating the occurrence of a reaction. Solubility tests, gel permeation chromatography, and scanning electronic microscopy confirmed the formation of a graft copolymer generated in situ during the melt blending. These results also indicate that this graft copolymer contains CC bond between SMA and PU chains. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2514–2524, 2001
Synthesis and characterization of the biodegradable copolymers from succinic acid and adipic acid with 1,4‐butanediol
Authors: Ahn B. D. , Kim S. H. , Kim Y. H. , Yang J. S. 
Published: October 2004

AbstractBiodegradable homopolyesters such as poly(butylene succinate) (PBSU) and poly(butylene adipate) (PBAD) and copolyesters such as poly(butylene succinate‐co‐butylene adipate) (PBSA) were synthesized, respectively, from succinic acid (SA) and adipic acid (AA) with 1,4‐butanediol through a two‐step process of esterification and deglycolization. The polyester compositions and physical properties of both homopolyesters and copolyesters were investigated by 1H– and 13C–NMR, DSC, GPC, WAXD, and optical polarizing microscopy. The melting point (Tm) of these copolyesters decreased gradually as the contents of butylene adipate increased and the glass‐transition temperature (Tg) of these copolyesters decreased linearly as the contents of the adipoyl unit increased. PBSA copolyesters showed two types of XRD patterns of PBSU and PBAD homopolyesters. Furthermore, the biodegradation and hydrolytic degradation of the high molecular weight PBSU homopolyester, PBAD homopolyester, and PBSA copolyesters were investigated in the composting soil and NH4Cl aqueous solutions at a pH level of 10.6. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2808–2826, 2001
Synthesis and pyrolysis of polysilazane precursors containing linear–cyclic structures for Si/N/C‐based ceramics
Authors: Xu Caihong , Liu Chunjuan , Zheng Zhimin , Li Yongming , Zhang Zhijie , Yang Shiyan , Xie Zemin 
Published: October 2004

AbstractA new kind of polysilazane precursor containing linear–cyclic structure was synthesized from the de‐lithium chloride condensation reaction of hexamethylcyclotrisilazane lithium salts (D) and 1,3‐dichlorotetraorganodisilazanes [(ClR1R2Si)2NH]. Pyrolyses of these precursors and some comparable linear polysilazanes were carried out at 900 °C in nitrogen. The results indicated that the existence of linear–cyclic structure in precursors provided relatively crosslinked or branched structures, which were helpful for improving ceramic yields. The precursor containing a linear–cyclic structure as well as reactive vinyl groups gave the highest pyrolytic yields. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2827–2831, 2001
Effects of polymer solvents on the performance of cellulose acetate membranes in methanol/methyl tertiary butyl ether separation
Authors: Tabe‐Mohammadi Abdulreza , Villaluenga Juan P. Garcia , Kim Hyo J. , Chan Theresa , Rauw Vanessa 
Published: October 2004

AbstractThe performances of cellulose acetate membranes prepared with casting solutions, with acetone, dimethylformamide (DMF), and N‐methylpyrrolidone (NMP) as solvents, were studied in a series of methanol/methyl tertiary butyl ether separation experiments. The flux and selectivity of the membrane samples were affected by the type of solvent used to prepare the casting solution. The sample with DMF consistently gave the highest selectivity and lowest flux, followed by the samples with NMP and acetone. The differences in the performances were attributed to the effects of the volatility and evaporation rates of the solvents. Scanning electron microscopy and atomic force microscopy techniques were used for comparing the morphologies of the membranes. In addition, we used Raman spectroscopy as a novel technique to study the sorption selectivities of the membrane samples prepared with the three different solvents. In a parallel study, the relation between the polymer concentration in the casting solution and the morphology and performance of the membrane samples was studied. Under similar preparation conditions, the morphology of the membrane changed from being porous to being dense when the membrane was prepared with casting solutions with increasing polymer concentration. Also, the selectivity increased and the permeability decreased with increasing polymer concentration in the casting solution. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2882–2895, 2001
Formation of hollow fibers in the melt‐spinning process
Authors: Rwei Syang‐Peng 
Published: October 2004

AbstractThis article reports an investigation of the formation of hollow fibers in a melt‐spinning process. Experimental results indicate that die swelling is largely responsible for a negative effect on hole formation. The factors that positively affect die swelling, including a decrease in temperature, a decrease in capillary length, and an increase in shear rate, are thus not recommended for the spinning of hollow fibers. For vinyl‐type polymers such as polypropylene, in which the apparent elasticity leads to serious die swelling, the formation of hollow fibers is more complex than that of a typical condensation polymer. Our results further demonstrate that when hollow fibers are being made in a variety of shapes (but of the same denier), spinning a polygonal hollow fiber is significantly more unstable than spinning a circular one. Moreover, an asymmetric bridge along the polygonal contour leads to a melt twist and interrupts the entire spinning process. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2896–2902, 2001
Natural zeolite polypropylene composite film preparation and characterization
Authors: Özmihçi F. , Balköse D. , Ülkü S. 
Published: October 2004

AbstractIn this research, the preparation and characterization of polypropylene (PP) and natural zeolite composites were studied. Natural zeolite mined in Gördes, Turkey was used as an alternative filler to CaCO3. Films were prepared by the extrusion of PP, and surface‐modified zeolite was made by polyethylene glycol 4000 with 2–4% zeolite. Zeolite‐filled composites had densities between 0.73 and 0.83 g/cm3 and had void fractions of 0.07–0.20. Although the permeability of water vapor through 2% zeolite‐filled composites was very small, 4% zeolite‐filled films had very high permeabilities. The yield stresses of 2–4% zeolite‐containing films were around 26–27 N/mm2 and were lower than that of PP, which indicated no adhesion between PP and zeolite. The effect of zeolite on the thermal degradation behavior in air and in a N2 atmosphere was also studied. In air, zeolites did not cause the oxidation of PP. In a N2 atmosphere, although the start of the thermal degradation of PP was retarded by zeolite, composites degraded at a faster rate than PP once the degradation started. At a processing temperature of 200°C, zeolites had no effect on the degradation of PP. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2913–2921, 2001
Blends of polypropylene with poly(vinyl butyral)
Authors: Cascone E. , David D. J. , Di Lorenzo M. L. , Karasz F. E. , Macknight W. J. , Martuscelli E. , Raimo M. 
Published: October 2004

AbstractThe thermal stability, crystallization behavior, and morphology of poly(vinyl butyral) (PVB) with differing compositions of vinyl alcohol and butyral units were investigated. It was found that the glass‐transition temperature of PVB decreases with increasing concentration of butyral units, mainly because of the reduced number of hydrogen bonds between hydroxyl groups of the chains. PVB samples with high vinyl alcohol content (≥63.3% by weight) are crystallizable and present an endothermic melting peak in the range 170–220°C. The thermal stability of PVB is also influenced by composition and increases with the number of butyral units. The thermal and crystallization characteristics of PVB were compared with those of neat polyvinyl alcohol (PVA), and the differences explained in terms of molecular structure. Two amorphous PVB samples, containing 31 and 14 wt % of vinyl alcohol units, respectively, were blended with isotactic polypropylene grafted with maleic anhydride (PP–MA), the latter of which was present to favor compatibilization of the components through chemical reaction or dipolar interactions involving the anhydride groups of the PP–MA and the hydroxyl groups of PVB. Properties of PP–MA/PVB 90/10 blends, prepared by melt extrusion, were compared to those of neat PP–MA. Both the PVBs used were immiscible with PP–MA, as indicated by the invariance of glass‐transition temperatures with the composition of the blends. However, a high level of compatibility between the components was achieved because the blends showed good mechanical properties that were comparable to, or even superior to, those of neat PP–MA. The analysis of the crystallization kinetics, performed both in isothermal and nonisothermal modes, showed that crystallization of polypropylene is only slightly influenced by the presence of the PVB phase. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2934–2946, 2001
Off‐line monitoring of butyl acrylate and vinyl acetate homopolymerization and copolymerization in toluene
Authors: Jovanović Renata , Dubé Marc A. 
Published: October 2004

AbstractA study of butyl acrylate (BA) and vinyl acetate (VAc) solution homopolymerization and copolymerization in toluene was carried out. The conversion and copolymer composition were monitored using traditional techniques (gravimetry and 1H‐NMR spectroscopy) and attenuated total reflectance‐Fourier transform IR (ATR‐FTIR) spectroscopy with a diamond‐composite probe and light conduit technology. The peak height of the characteristic absorbances of the monomer(s) during the course of the reaction was used to calculate the conversion and copolymer composition for the ATR‐FTIR monitoring. The data obtained using a ReactIR™ 1000 reaction analysis system in the off‐line mode showed very good agreement with data obtained using traditional techniques. The solvent effects on BA and VAc solution homopolymerizations and copolymerizations in toluene were also investigated. Improvement to model predictions was obtained by allowing the lumped constant (kp/k) to vary with the solvent concentration. Experimental data and model predictions of the number‐ and weight‐average molecular weights for the investigated systems are also presented. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2958–2977, 2001
Suspension characteristics of borate‐crosslinked gels: Rheology and atomic force microscopy measurements
Authors: Goel Naval , Shah Subhash N. , Yuan Wei‐Li , O'Rear Edgar A. 
Published: October 2004

AbstractBorate‐crosslinked guar gels were prepared and characterized to understand their capability to suspend and transport sand particles through a fracture created in a petroleum reservoir. In this study the crosslinked gels were formulated by varying the borate crosslinker concentrations that were selected such that the gels satisfied the minimum viscosity criteria (100 cP at 100/s) used to evaluate crosslinked gels for their suspension capabilities. However, some of these gels did not exhibit satisfactory particles transport through a slot that models a parallel fracture. These gels were then characterized using oscillatory measurements and atomic force microscopy (AFM) to understand the influence of the microscopic behavior of the crosslinked gels on their macroscopic performance in the slot. The results showed that the suspension transport characteristics of these gels could be described through crosslinked networks formed across the guar polymer. The AFM images and rheological measurements of these gels suggest that the elastic modulus provides more useful information than the viscosity about the crosslinked gel structure and their capability to suspend sand particles. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2978–2990, 2001
Modification of three‐component bismaleimide resin by poly(phthaloyl diphenyl ether) and related copolymers
Authors: Iijima Takao , Yuasa Noriyuki , Tomoi Masao 
Published: October 2004

AbstractA three‐component bismaleimide resin, composed of 4,4′‐bismaleimidodiphenyl methane (BDM), o,o′‐diallyl bisphenol A (DBA), and o,o′‐dimethallyl bisphenol A (1.0/0.3/0.7 eq ratio) was used as a parent bismaleimide resin. Modification of the three‐component bismaleimide resin was examined by blending it with poly(ether ketone ketone)s. Poly(ether ketone ketone)s include poly(phthaloyl diphenyl ether) (PPDE), poly(phthaloyl diphenyl ether‐co‐isophthaloyl diphenyl ether) (PPIDE), and poly(phthaloyl diphenyl ether‐co‐terephthaloyl diphenyl ether) (PPTDE). The PPIDE (51 mol % isophthaloyl) and PPTDE (44 mol % terephthaloyl) were more effective as modifiers for the bismaleimide resin than was PPDE. For example, the fracture toughness (KIC) for the modified resin increased 30% with no deterioration in the flexural strength and modulus with a 15 wt % inclusion of PPTDE (MW 23,400) compared to the parent three‐component bismaleimide resin: the KIC increased 95% compared to the value for the Matrimid 5292 resin composed of BDM and DBA. The morphologies of the modified resins changed from particulate to cocontinuous phase structures, depending on the modifier structure and concentration. Toughening of the cured bismaleimide resin could be achieved because of the cocontinuous phase structure. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2991–3000, 2001
Experimental estimation of gas‐transport properties of linear low‐density polyethylene membranes by an integral permeation method
Authors: Villaluenga J. P. G. , Seoane B. 
Published: October 2004

AbstractIn recent years, we have investigated gas‐transport phenomena in coextruded linear low‐density polyethylene (LLDPE) membranes. For the most part, coextruded LLDPE membranes were investigated because of their excellent mechanical properties, which explain their extensive use in the packaging industry. Because of the small thickness of coextruded LLDPE membranes, significant errors can be involved in the determination of the diffusion coefficient of gases in the membranes by the time‐lag method. To obtain more precise transport parameters for LLDPE membranes, we determined the permeability and diffusion coefficients for O2, CO2, He, and N2 from 298 to 348 K by employing an alternative method recently developed. The results indicate that the procedure used in this study for determining the diffusivity of gases in membranes was precise and more efficient than a method based on the evaluation of the time‐lag parameter. With respect to permeability, the coefficients obtained in this work agree satisfactorily with those obtained by the time‐lag method. In general, the permeability and diffusivity results are in satisfactory agreement with the literature values reported for semicrystalline polyethylene membranes. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3013–3021, 2001
Interfacial and mechanical properties of γ‐Fe2O3/segmented polyurethane/poly(vinyl chloride) composites
Authors: Sudaryanto  , Nishino Takashi , Ueno Masaki , Asaoka Seiji , Nakamae Katsuhiko 
Published: October 2004

AbstractSegmented polyurethane (SPU)/poly(vinyl chloride) (PVC) blends were particulated with γ‐Fe2O3. Interfacial properties of the composite were studied through the adsorption behaviors of SPU and PVC and their blends on γ‐Fe2O3 particles surface. Mechanical properties of the composite were measured with dynamic mechanical analysis and tensile test measurements. PVC with functional groups (FPVC), because of strong interactions, showed preferential adsorption on γ‐Fe2O3 compared with SPU and PVC. Moreover, the γ‐Fe2O3 particles were covered by FPVC in the γ‐Fe2O3/SPU/FPVC composite. The adsorption layer of FPVC protected SPU from catalytic degradation by γ‐Fe2O3, resulting in increasing hydrolytic stability for SPU. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3030–3035, 2001