bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies of jute fiber composites with polyesteramide polyols as interfacial agent
Authors: Mukherjea R. N. , Pal S. K. , Sanyal S. K. 
Published: April 2003

AbstractPolyesteramide polyols have been synthesized by melt condenstion using a mixture of alkanolamines, polyethylene glycols, and dicarboxylic acids/anhydrieds, and the behavior or resin samples as interfacrial agents in unidirectional as well as random composites of jute/epoxy and jute/polyester has been evaluated. Mechanical properties of these composties with or without interfacial agents have been determined along with the effect of water uptake on such properties. The incorporation of polyesteramide polyol (PEAP) resins as interfacila agents has been found to significantly improcve the mechanical properties of jute fiber composites. It has also been found that increasing the hydroxyl value of PEAP results in a better bonding of the composities up to a certain optimum limit of hydroxyl value beyond which the molecular weight of the interfacila agent as well as its bonding strenght decreases. Use of PEAP resin of optimum hydroxyl value and molecular weight also significantly improves the water resistance capacities of jute/epoxy composites.
Equilibrium disperse‐dye sorption by isotactic polypropylene films of varied thermal histories
Authors: Yonetake Koichiro , Masuko Toru , Shimanuki Tomoyuki , Karasawa Mikio 
Published: April 2003

AbstractSpherulitic polypropylene (PP) films prepared by a melt‐quenched process and then exposed to isothermal annealing treatments at various temperatures ranging from 120°C to 155°C have been dyed at 80°C with C.I. Disperse Yellow 7(Y‐7) or p‐aminoazobenzene. Different PP films as crystallized isothermally in the range of 60°C to 155°C have also been dyed with the same dyes. The equilibrium dye sorption (Mo) obtained for these films increased slightly with an increase in polymer volume crystallinity (Cu). Using fine structural data of these films, the change in Mo were analyzed in terms of the mosaic‐block structural model; e.g., the values of Mo were divided into sorption by the amorphous end region (Me) located between lamella surfaces and sorption by the amorphous side region (Ms) located between crystalline cores parallel to the molecular chain axis. The value of Ms increased with increasing Cv in both cases of the dyeing systems, while the value of Me decreased monotonically in an opposite manner. The amorphous chains in the side region seem to have a strong affinity to a long rodlike dye molecule of Y‐7; this feature is considered to be associated with the extended chain conformation of the side region which originates from distorted lattice chains.
Ionically crosslinked poly(acrylic acid) membranes. IV. Composite reverse osmosis membranes
Authors: Huang R. Y. M. , Gao C. J. , Kim J. J. 
Published: April 2003

AbstractComposite reverse osmosis membranes of ionically crosslinked poly(acrylic acid) (PAA) have been prepared. The process consists of coating a porous polysulfone membrane with a thin layer of dilute solution of PAA, drying the thin liquid layer, and ionically crosslinking the PAA in solutions of different salts. The influence of some important preparation parameters on the properties of these membranes was investigated. It was found that all these membranes possessed ion exchange properties and could be ion exchanged; some of them have been found to be suitable for the desalination of low concentration salt solutions. By comparison to cellulose acetate (CA) membranes, higher rejection of phenols may be an interesting property of these membranes.
Dynamic mechanical properties of photopolymerizable poly(vinyl alcohol)–acrylate monomer blends
Authors: Koshiba Mitsunobu , Yamaoka Tsuguo , Tsunoda Takahiro 
Published: April 2003

AbstractDynamic mechanical properties of photopolymerizable poly(vinyl alcohol) (PVA)–monoacrylate blends were investigated by measuring dynamic shear modulus G′ and loss tangent, tan δ. The dynamic mechanical properties of the blends before being exposed to UV irradiation were governed by the weight percent of the monomers which act as plasticizers. On the other hand, the UV‐irradiated blends seemed to be typical two‐phase materials since they revealed two tan δ maxima whose positions were independent of the monomer content. Those two maxima were assigned to PVA and photopolymerized acrylates with reference to the dynamic mechanical data of PVA and a PVA‐polyacrylamide polyblend. Those dynamic mechanical data suggested that insolubilization of the blend type photopolymers should be caused by a decrease in solubility due to graft polymerization of acrylate monomers onto PVA.
Rigid polar composite supports for use in solid phase synthesis
Authors: Akelah A. , Heffernan J. G. , Kingston S. B. , Sherrington D. C. 
Published: April 2003

AbstractA number of particulate polyethylene and polypropylene based matrices have been γ ‐radiation grafted with poly(acryloylsarcosine methyl ester). The resulting composite materials have physicochemical properties attractive for use in continuous solid phase synthesis. Three macroporous polystyrene resins have also been impregnated with a secondary polyamide network using thermal initiation. All of these retain their rigid spherical structure and the composite properties again make them good candidates for use under pressure. One of these has been used in a preliminary solid phase experiment and two successive amino acid residues coupled with ∼100% yield.
Chemorheology of thermosetting resins. III. Effect of low‐profile additive on the chemorheology and curing kinetics of unsaturated polyester resin
Authors: Lem Kwok‐Wai , Han Chang Dae 
Published: April 2003

AbstractAn experimental study was conducted to investigate the effect of low‐profile thermoplastic additives on the rheological behavior during cure and the curing kinetics of unsaturated polyester resin. For the study, a general‐purpose polyester resin was used and two different types of thermoplastic additive, poly(vinyl acetate) (PVAc) and poly(methyl methacrylate) (PMMA), were used as low‐profile additives. It has been found that, during cure, the resin/PMMA system exhibits shearthinning behavior even before the cure time reaches the critical value tη∞ whereas the resin/PVAc system does not. Also, both PVAc and PMMA help reduce the shrinkage of the resin during cure. However, our study shows that shrinkage control becomes effective only when the shear rate is greater than a certain critical value. The curing behavior determined with the aid of differential scanning calorimetry (DSC) shows that the rate of cure and the final degree of cure are decreased when the amount of low‐profile additive is increased.
Ionic heterogeneities in sulfonated polysulfone films
Authors: Sivashinsky N. , Tanny G. B. 
Published: April 2003

AbstractMeasurements of glass transition temperature, small‐angle x‐ray scattering (SAXS), and transmission electron microscopy (TEM) have been applied to the study of ionic heterogeneities in sulfonated polysulfone (SPS) films. The SAXS study confirms the existence of heterogeneities in the electron density distribution, whose appearence for the Cs+1, Ca+2, and Fe+3 forms of SPS but not for H+ suggests that the scattering centers are ion‐containing regions. However, a TEM study could not detect the existence of microseparated regions down to a level of 50 Å and the Tg behavior as a function of IEC was more typical of that for random copolymers. A Mössbauer study, performed earlier by Heitner‐Wirguin et al. on samples of our material, indicated the existence of clusters ∼35–40 Å in diameter.
Effect of stabilizer type on the mechanical properties of rigid poly(vinyl chloride). I
Authors: Younan M. Y. A. , El‐Rifai M. A. , Mohsen R. , El‐Hennawi I. M. 
Published: April 2003

AbstractThe effect of stabilizers on the mechanical properties of UPVC and how these are affected by different formulations has been studied. Three stabilizers, tin mercaptide MT, lead system Pb, and Ba/Cd/Zn complex BCZ, were used. A high ‐intensity blender was used for dry blend compounding, and the blend was injection ‐molded on a Kuasy single Screw injection molding machine. A two ‐cavity mold was made for forming the specimens. The specimens were tested for their impact strength, fracture toughness, tensile strength, and flexural strength. Increasing MT stabilizer was shown to increase the tensile strength and to decrease fracture toughness, impact strength, and ductility; this was attributed to antiplasticization. Increasing the Pb stabilizer conferred ductility and improved fracture toughness and impact strength. It is concluded that stabilizers have a marked effect on the mechanical behavior of rigid PVC.
Time‐dependent characteristics of sulfonated EPDM containing zinc stearate. I. Thermal behavior
Authors: Weiss R. A. 
Published: April 2003

AbstractThe crystallization and melting of zinc stearate (ZnSt) in ZnSt‐plasticized compositions of ethylene–propylene–diene terpolymer (EPDM) and sulfonated EPDM (S‐EPDM) have been studied by differential scanning calorimetry. While immiscible in both EPDM and S‐EPDM, ZnSt is compatible with the latter. This compatibility presumably arises from either electrostatic or dipole–dipole interactions between the carboxylate functionality of ZnSt and the sulfonate groups of the polymer. The crystallization behavior of ZnSt is significantly perturbed when the material is added to S‐EPDM, and the crystalline ZnSt phase that results is strongly time dependent. ZnSt first crystallizes as small imperfect crystals when the compositions are cooled from the melt, but it eventually anneals at room temperature into larger, more perfect crystals. Time dependent changes in the mechanical properties of these compositions are also demonstrated and it is suggested that this may be due in part to changes in the ZnSt morphology.
Comparison between a linear and a branched low‐density polyethylene
Authors: Attalla G. , Bertinotti F. 
Published: April 2003

AbstractTwo low‐density polyethylenes, a linear low‐pressure (LLDPE) and a branched high‐pressure (LDPE), have been compared. Their shear and extensional behavior and melt fracture phenomena have been investigated, and some mechanical and optical properties of their blown films have been measured. The rheological analysis showed major differences between the samples, both in shear viscosity and in elongational viscosity. The LLDPE exhibited two types of melt fracture, the first of which—a fine scale extrudate roughness—was not shown by the LDPE and appeared at a very low shear rate. The concomitance in LLDPE of a high shear viscosity and a low elongational viscosity and the presence of melt fracture at low shear rate resulted in its more difficult processing into film. The mechanical properties of the LLDPE film approached those of high‐density polyethylene while the optical characteristics were in the range of LDPE. Such a coexistence of properties makes LLDPE an interesting material for film production.
Radiation crosslinking of poly(vinyl chloride) with trimethylolpropanetrimethacrylate. IV. Effect of diundecyl phthalate: Dependence of physical properties on composition
Authors: Bowmer T. N. , Vroom W. I. 
Published: April 2003

AbstractBlends of poly(vinyl chloride) (PVC) with polyfunctional monomers may be crosslinked by ionizing radiation. The physical properties of PVC blended with trimethylolpropanetrimethacrylate (TMPTMA) and diundecyl phthalate (DUP) were studied. The TMPTMA monomer crosslinked the blend by homopolymerization and/or grafting to PVC. The plasticizer, DUP, was chemically inert under irradiation but, by plasticizing the macromolecules and diluting the monomer, changed the kinetics extensively. Characteristics of the glass transitions and the tensile mechanical properties have been correlated with blend composition and radiation dose. Before irradiation, poly(vinyl chloride) was plasticized by both DUP and TMPTMA monomer. The increase in glass transition temperature and mechanical strength following irradiation to 5 Mrad was correlated with the TMPTMA content of the blend. Both the molecular structure of the network and the DUP content of the blend were factors in determining the physical properties of the final crosslinked blend. The molecular structure was determined by the kinetics of the crosslinking reactions, which in turn were determined by the blend composition. A molecular interpretation consistent with the physical properties, chemical kinetics, and mechanism of the crosslinking system has been presented.
Effects of low molecular weight aliphatic diols on the polyurethane elastomers prepared from hydroxyl‐terminated polybutadienes
Authors: Idage B. B. , Vernekar S. P. , Ghatge N. D. 
Published: April 2003

AbstractHydroxyl‐terminated polybutadienes were prepared by using azo initiators such as di(4‐hydroxybutyl)‐2,2′‐azobisisobutyrate and di(3‐hydroxybutyl)‐2,2′‐azobisisobutyrate, one of which contains primary and the other secondary hydroxyl groups. The effects of aliphatic diols and 2,4‐toluene diisocyanate (TDI) in the presence of dibutyltindilaurate (DBTDL) as catalyst, on crosslinking of primary and secondary hydroxyl groups, were studied. Polyurethane elastomers from these polymers are prepared by using different ratios of diols, 2,4‐toluene diisocyanate and catalyst. Physical properties such as hardness, tensile strength, 100% modulus, and elongation at break of these polymers were studied with a view to compare them with the physical properties of elastomers prepared from ARCO R‐45M.
Properties of filaments spun from poly(ethylene terephthalate) chips containing PET–dust
Authors: Datye Keshav V. , Duraiswamy R. 
Published: April 2003

AbstractIt is observed that the thick portions in a poly(ethylene terephthalate) (PET) filament differ from the rest in their solution viscosity and birefringence, indicating that they are caused by the inhomogeneity of the polymer melt. To identify the cause of the latter, the PET chips are critically examined. It is found that the waferlike tails on the edge of the PET chips and PET–dust have slightly higher viscosity than the chips. The behavior of the chips and the dust during drying and melt spinning are examined to find whether the dust becomes postpolymerized during drying. Such dried PET–dust exhibits substantially different melting behavior than the chips. The filaments spun from the mixture of chips and PET–dust exhibit significantly higher nonuniformity in properties than the filaments spun from the chips only. It is concluded that the PET–dust entering the extruder with the chips can cause thick portions in the filaments.
A combustibility study of the gaseous pyrolysates produced from some high‐performance fabrics
Authors: Day M. , Suprunchuk T. , Wiles D. M. 
Published: April 2003

AbstractThe flammability limits of the gaseous pyrolysates obtained from a series of conventional, flame‐retarded, and high‐performance textile fabrics have been measured, and the results compared. These data have been utilized to develop a fire hazard index associated with the ignitability and combustibility of the gaseous products of thermal degradation as a result of exposure to a high radiative thermal fire load. Generally, it was found that the high‐performance fabrics behaved better than the flame‐retarded fabrics, which themselves were superior to untreated materials.
The viscosity of an unsaturated polyester
Authors: Kaštánek Alois , Zelenka Jiří , Hájek Karel 
Published: April 2003

AbstractThe zero‐shear viscosities of the fractions of an unsaturated polyester were determined by using a rotation viscosimeter with cone‐and‐plate measuring system. The polyester was prepared by the generally known melt condensation of maleic anhydride, phthalic anhydride, ethylene glycol, and cyclohexanol. The viscosity–temperature relationship and the viscosity‐molecular weight relationship are given. The low value of the critical molecular weight as well as rather high value of the inherent friction factor are probably caused by high forces between polar groups of the chains of an unsaturated polyester.
Protective effect of the phenyl group in γ‐irradiated compatible blends of poly(methyl methacrylate) and poly(styrene‐co‐acrylonitrile)
Authors: Nguyen T. Q. , Kausch H. H. 
Published: April 2003

AbstractThe sensitivity to radiation of mixtures of poly(methyl methacrylate) (PMMA) and polystyrene‐co‐acrylonitile) (SAN) was studied over the entire range of composition. Polystyrene‐co‐acrylonitrile, like polystyrene, is highly resistant to ionizing radiation, having a small Gx value for crosslinking (0.077) and an even smaller Gs value for main chain scission (0.055). In contrast, PMMA degrades readily under irradiation (with Gs = 1.2). In γ‐irradiated blends, the behavior of each polymer is largely influenced by the presence of the other component. Gel formation in SAN is impeded by PMMA, as a result of a decrease in Gx, and a concomitant increase in the ratio Gs/Gx. Flexural strength measurements, along with molecular weight determinations by gel permeation chromatography, demonstrated that SAN had a marked protective effect on PMMA by decreasing Gs (chain scission). This protective effect was not observed in earlier experiments with PMMA–PS blends, in spite of its chemical similarity to the system PMMA–SAN. The difference in behavior between PMMA–PS and PMMA–SAN may be explained on the basis of polymer compatibility. PMMA and SAN form a compatible pair, whereas PMMA and PS are incompatible; thus the short range protective effect of the phenyl groups in PS is inhibited.
The effect of phase separation on the structure and permeability of gelatin–dextran films
Authors: Petrak K. L. 
Published: April 2003

AbstractThe effect of polymer–polymer phase separation on the transport properties of gelatin–dextran films has been studied. In the gelatin–dextran–water system, the phase separation and gel formation do not occur due to the presence of a nonsolvent, but depend entirely on the temperature and the total polymer concentration. It has been found that the permeability of polymer blend films to aqueous solutes can be varied not only by changing the volume ratio of the phases, but also by varying the size of the individual domains of the two phases in the films. Under the conditions of restricted demixing (e.g., after gel formation), the course of the phase separation process can be changed by varying the length of time allowed for unrestricted separation. The two most important parameters affecting the result are the total polymer concentration in the casting solution, and the temperature regime. An exponential dependence of the permeation coefficient on the volume fraction of the solvent in the film is shown.
Thiol modification of difunctional castor oil and its utility as room temperature setting elastomeric material
Authors: Mahajan S. S. , Ghatge N. D. , Khisti R. S. 
Published: April 2003

AbstractDifunctional castor oil has been reacted with thioglycolic acid for the synthesis of castor oil dithioglycolate (CODT). Elastomeric products have been obtained from CODT alone and in combination with liquid polysulfide polymer LP‐33 by oxidative cure with manganese dioxide. Semireinforced (SRF) carbon black has been used as a filler. CODT has also been evaluated as a flexibilizer for liquid epoxy resin (Synpol 200).
Thermoplastic polyurethane elastomers—thermostability in relation to composition
Authors: Masiulanis Bogumila 
Published: April 2003

AbstractThe dependence of thermal stability of poly(ester‐urethane) elastomers on their composition was investigated. For polyurethanes of hard segment content above 3070, hydroquinone di(β‐hy‐droxyethyl) ether (HQEE) is the choice for good thermomechanical stability while the stability of bisphenol‐A‐based polymers is rather poor. The temperature sensitivity of modulus was essential in the range of ‐30‐24OC, while in the range of 24–70°C i t is moderate. The modulus in the low temperature region depends on the nature of polyesterdiol. Its drop with temperature is lower for poly(hexamethy1ene carbonate) glycol (PHC)‐based polyurethanes than poly(ethy1ene‐adipate) glycol (PEAd)‐based ones. In the high temperature region it also depends on the nature and amount of hard segments. The thermal stability of 4,4′‐dicyclohexylmethane diisocyanate (SMD1)‐based polyurethanes is inferior to the one for 4,4′‐diphenylmethanediisocyanate (MD1)‐derived polymers.
Properties of asymmetric polyimide ultrafiltration membranes. I. Pore size and morphology characterization
Authors: Sarbolouki Mohammad N. 
Published: April 2003

AbstractProperties of asymmetric UF membranes made by solution casting of aromatic polyimides as a function of fabrication conditions are reported. The characteristic properties investigated include: the overall porosity, hydraulic permeability, the equivalent pore size of the skin layer (via a newly developed general diagram), and morphological features shown by the scanning electron microscope. It was found that as casting solution concentration and/or evaporation period was increased, the average pore size decreased while the skin thickness increased. At low casting solution concentrations the membranes were highly porous and the precipitated polymer phase had a granular structure consisting of aggregates of precipitated polymer micelles. While at high concentrations marcrovoid porosity was reduced but the precipitated polymer phase had a spongy structure. The interstitial openings of the granular skin structure of a membrane made from 15% polymer solution with no evaporation as revealed by SEM showed pore size values that were close to those calculated through pore models.
Novel method of preparing Ag–Hg alloy on polyacrylamide films and their structure
Authors: Lee Jiunn Yih , Tanaka Hisashi , Takezoe Hideo , Fukuda Atsuo , Kuze Eiichi , Iwanaga Hiroshi 
Published: April 2003

AbstractA novel method is proposed of preparing thin Ag–Hg alloy on PAAm film surface at room temperature: The film of interest is formed by holding PAAm aqueous solution with AgNO3 in Hg‐saturated atmosphere. Two kinds of films, one of which is a conductor and the other an insulator, can be selectively formed with pH‐controlled PAAm solution by ammonia. The conducting surface is assigned to the α phase of Ag–Hg alloy by means of X‐ray analysis. Potentiometric titration and IR spectral studies suggest the existence of PAAm–Ag+ complexes. On the basis of their structure and the oxidation and reduction potential of Ag+ and Hg2+, the mechanism of film formation is also discussed.
Very slow crack growth during osmosis in epoxy and in polyester resins
Authors: Sargent J. P. , Ashbee K. H. G. 
Published: April 2003

AbstractIt has been demonstrated that osmotic pressure filled cracks in both epoxy and polyester resins are elastic cracks. Use of classical formulas for elastic cracks has enabled estimates to be made of the time dependence of Young's modulus for both resins. Use of linear elastic fracture mechanics formulas has enabled stress intensity factors to be determined from measurements of crack profiles. Radical crack growth rates are small, in the range 10−12–10−9 ms−1 for hot water tests, and remain constant over a wider range of stress intensity factor, from 0.3 to 0.8 MPa.m1/2. To a first approximation, constant radial growth rate is compatible with a diffusion controlled mechanism. However, analysis of the data indicates an activation energy of ∼50 kcal. Some evidence is presented for concluding that, in polyesters at least, the true nature of crack propagation can be by way of slip/stick.