bluuebunny/crossref_metadata_2025_split huggingface dataset:
A dynamic‐mechanical study of polycarbonate‐polyester blends
Authors: Li Yuan , Williams H. Leverne 
Published: April 2003

AbstractBisphenol‐A polycarbonate and an aromatic linear copolyester were melt blended for dynamic mechanical tests using a Dynastat. Corresponding powders were used in thermal analysis by differential scanning calorimetry. The deduced glass transition temperatures of the pure polymers and blends were compared to estimate the miscibility of the two polymers.
The effect of sulfur‐ and nitrogen‐containing fire retardants on reducing the flammability of a polychloroprene composition used for cables
Authors: Karaivanova M. , Mihailova N. , Gjurova K. 
Published: April 2003

AbstractThe influence of ammonium sulfamate (AS) independently or in a combination with antimony trioxide (AO) and chloroparaffin (ChP)–70% chlorine, on the oxygen index (OI) values as a flammability indicator, as well as on some physicomechanical and thermal characteristics of filled and unfilled compositions for cables based on chloroprene rubber (ChR), is studied here. It is found out that, at definite concentrations, AS and AO reveal an additive effect as fire retardants, decreasing the rate of heat rlease on heating. AS reveals a plasticizing effect as well.
Synthesis and characterization of new aromatic polyamides, polyimides, and polyureas containing 1,3,5‐triazine rings
Authors: Lin Jui‐Kun , Yuki Yasuo , Kunisada Hideo , Kondo Shuji 
Published: April 2003

AbstractNovel aromatic polyamides, polyimides, and polyureas containing 1,3,5‐triazine rings were pre‐pared by the reaction of 2‐anilino‐4‐aminoanilino‐6‐aminophenyl‐1,3,5‐triazines with aromatic dicarboxylic acid chlorides, pyromellitic dianhydride, and diisocyantes, respectively. All polymers were soluble in polar aprotic solvents such as N,N‐dimethylformamide, N,N‐dimethylacetamide, dimethyl sulfoxide, and pyridine. The glass transition temperatures of polymers were in the range of 220–260°C. The thermal stabilities of polymers were evaluated by thermogravimetric analysis in air. These polymers were stable up to 420°C for polyamides, 470°C for polyimides, and 300°C for polyureas.
Stress relaxation of reptating chains of acrylonitrile–butadiene copolymer in end‐linked acrylonitrile–butadiene copolymer networks
Authors: Liu Weilian , He Tianbai 
Published: April 2003

AbstractStress relaxation of unattached chains of acrylonitrile–butadiene copolymer in TDI end‐linked acrylonitrile–butadiene copolymer has been studied. The advantage of this system is that the polar nature of the TDI crosslinking agent in end‐linked acrylonitrile–butadiene copolymer can be compensated if an unattached acrylonitrile–butadiene copolymer with moderate acrylonitrile content is selected. It was found that with increasing unattached chain content, the position of the relaxation spectra transitions shifted to shorter times. The frictional resistance for the relaxation of networks containing unattached chains was proportional to the amount of crosslinked components. This means that crosslinked components not only bear load but also resist the relaxation of unattached chains. The relaxation moduli contribution from unattached chains first increased and then decreased with increasing amount of crosslinked components. This can be explained by the presence of two kinds of entanglements, i.e., those between unattached chains themselves and those between unattached chains and crosslinked components, which in turn depend on the amount of unattached chains. At lower concentrations of unattached chains, relaxation of unattached chains requires that molecules pass only through obstacles formed by one kind of entanglement; this results in lower relaxation modulus. With increasing unattached chain content, the relaxation of those chains require molecules reptation through both kinds of entanglements, which results in higher relaxation modulus. Therefore, the enhancement of mechanical properties for networks containing unattached chains originates not only from load‐bearing of crosslinked components but also from the relaxation of unattached chains.
A semiempiric model for establishing the drawability of solution‐spun linear polyamides and other flexible chain polymers
Authors: Smook J. , Vos G. J. H. , Doppert H. L. 
Published: April 2003

AbstractA series of high molecular weight, linear polyamide samples have been subjected to various solution spinning techniques, such as gel, wet, and dry spinning, in an attempt to produce high‐tenacity filaments. The spinning experiments involved polyamide 6, polyamide 12, and copolymers thereof, with a molecular weight Mw in the range of 105−106 kg/kmol. Filaments with a tenacity of 100 cN/tex have been obtained. Their draw ratio never surpassed a value of six, which may also be reached after conventional melt spinning. Apparently, the drawability of polyamides cannot be improved via solution spinning techniques, although a favorable molecular topology for accomplishing high draw ratios has most likely been realized. This behavior is in sharp contrast with the highly increased drawability after solution spinning of less polar polymers, such as polyethylene or polyvinyl alcohol. A semiempirical equation is now proposed that relates the maximum drawability of flexible chain polymers with their polarity, being expressed in terms of cohesive energy. A preassumption underlying this equation is that drawability is not limited by a high entanglement density as is, e.g., the case after melt processing.
Room temperature curing of CTBN‐toughened epoxy adhesive with elevated temperature service capability
Authors: Achary P. Sasidharan , Latha P. B. , Ramaswamy R. 
Published: April 2003

AbstractThe adhesive joint strengths at room temperature (25°C) and at 120°C for an epoxy resin cured at room temperature with tris (N,N‐dimethylaminomethyl) phenol and containing varying amounts of a carboxyl‐terminated polybutadiene‐acrylonitrile copolymer (CTBN) were investigated and reported. It was observed that as CTBN content increased, lap shear strength and T‐peel strength increased significantly and passed through a maximum at about 10 parts CTBN content per 100 parts epoxy resin and then decreased. To explain the observed results, the effect of CTBN content on the bulk tensile strength, impact energy, glass transition temperature (ETg), and morphology were also evaluated. SEM observations showed microphase separation between CTBN and epoxy matrix for the composition containing 10 parts CTBN per 100 parts epoxy resin, and this composition exhibited maximum bulk tensile strength and impact energy. The enhancement of bulk mechanical properties, hence the adhesive joint strength, was attributed to the higher toughness produced by the dispersed rubber particles. At higher CTBN content, the rubber phase became continuous, and the system exhibited a fall in mechanical properties, hence in adhesive joint strength, which was attributed to the flexibilization effect. The glass transition temperature of the cured epoxy resin was little influenced by CTBN incorporation up to 10 parts per 100 epoxy resin. Higher levels of CTBN content due to the flexibilization effect, decreased the ETg, hence the elevated temperature capability. The results of this study demonstrate that epoxy resins containing low levels of CTBN, cured at room temperature with tris (N,N‐dimethylaminomethyl) phenol can be used to formulate structural adhesives for use in elevated temperature environments.
The pyrolytic characterization of a surfactant/polymer/ceramic composite system using combined thermogravimetric analysis‐mass spectrometry
Authors: Nelson K. M. , Manson J‐A. E. , Seferis J. C. , Prime R. B. 
Published: April 2003

AbstractAn experimental technique of combined thermogravimetric analysis (TGA)‐mass spectrometry (MS) was used to study the pyrolysis process during binder removal from a ceramic/binder system. The effect of a fluorocarbon surfactant on the pyrolysis process was also investigated and it was discovered that the surfactant had no significant effect on pyrolysis. A simple paraffin binder system was implemented so as to enhance the effects of the surfactant. The identification of the fragments created during pyrolysis is also discussed.
Infrared spectra of alkali treated jute stick
Authors: Reddy S. S. , Bhaduri S. K. , Sen S. K. 
Published: April 2003

AbstractThe infrared spectra of alkaline jute stick have been discussed and compared to that of untreated and control sample. A higher shift in the OH and lower shift in the CH stretching frequencies were observed in alkaline sample. The presence of a strong band at 1440–1430 cm−1 may be due to the coupling of COO− frequency with CH2 deformation frequency. The CO stretching mode at 1240 cm−1 disappears on alkaline treatment with the formation of new peaks at 1265 and 1225 cm−1. The β−glucosidic band at 895 cm−1 is shifted to 880 cm−1 with doubled intensity in alkaline jute stick.
Retention of polyvinylpyrrolidone swelling agent in the poly(ether p‐phenylenesulfone) ultrafiltration membrane
Authors: Miyano Tadaaki , Matsuura Takeshi , Carlsson D. J. , Sourirajan S. 
Published: April 2003

AbstractThe detection and quantification of polyvinylpyrrolidone (PVP) polymer in the top skin layer of the poly(ether p‐phenylenesulfone) (PES, Victrex) ultrafiltration membrane was attempted by applying the technique of internal reflection Fourier transform infrared spectroscopy (FTIR‐IRS). The effects of the PVP concentration in the casting solution and that of the PVP molecular weight on the residual quantity of PVP were investigated in detail. The PVP content in the membrane was further correlated to the ultrafiltration performance data of PES membranes.
Further studies on the moisture‐related properties of hydrolyzed poly(ethylene terephthalate)
Authors: Zeronian S. Haig , Wang Hui‐Zhen , Alger Kenneth W. 
Published: April 2003

AbstractContact angle measurements with water indicate that the hydrophilicity of poly(ethylene terephthalate) (PET) film decreased in the order PET treated with aqueous sodium hydroxide > untreated PET > PET treated with methanolic sodium methoxide. When the sodium‐methoxidetreated polyester was hydrolyzed with caustic soda, its contact angle fell, indicating that the methyl ester groups formed during the sodium methoxide reaction by a base‐catalyzed ester interchange had been the cause of the high contact angles. Thus it appears that carboxyl groups at the surface of hydrolyzed PET play an important role in determining its hydrophilicity. It appears from adsorption experiments that there is a marked increase in the surface area of PET fibers on treatment with aqueous sodium hydroxide. The increase is attributed to the presence of the pits produced by the hydrolysis. It is suggested the higher surface area leads to increased numbers of hydrophilic groups on the fiber surface causing the greater wettability observed in the caustic hydrolyzed samples.
Aromatic polyamide–hydrazides for water desalination. I. Syntheses and RO membrane performance
Authors: Satre M. D. , Ghatge N. D. , Ramani M. P. S. 
Published: April 2003

AbstractWholly aromatic polyamide–hydrazides (PAH) were synthesized by low‐temperature solution polycondensation of m‐amino benzhydrazide (MABH)/p‐amino benzhydrazide (PABH) with isophthaloyl chloride (ICL)/terephthaloylchloride (TCl) in N,N‐dimethyl acetamide (DMAC)/N‐methyl‐2‐pyrrolidone (NMP). The polymers were characterized for their properties. Membranes were prepared from these (PAH) polymers under different casting conditions by varying the casting solution composition, evaporation time, post‐annealing treatment, etc. The reverse osmosis (RO) tests for these membranes were performed with 5000 ppm aqueous sodium chloride feeds at 40 and 70 kg/cm2 operating pressures. Addition of lithium chloride to casting solutions and annealing in hot water conferred optimum selectivity to RO membranes. Membranes showed rejections up to 98.5% at flux > 20 cm/day.
Measurement method and apparatus for monitoring the kinetics of polymerization and crosslinking reactions by microwave dielectrometry
Authors: Carlini C. , Rolla P. A. , Tombari E. 
Published: April 2003

AbstractThe experimental apparatus employed for monitoring fast polymerizing and crosslinking processes is described in detail. The measurement method for the particular application is widely discussed and the resulting performances of the measurement technique are reported. As an example, the experimental results for polymerization and crosslinking reactions of n‐butyl acrylate and 1,6‐hexandiol‐diacrylate are shown and the accuracy of the data acquisition is demonstrated.
Synthesis and characterization of 1,6‐and 1,7‐dihydroxy alkanes and their acrylic esters. I
Authors: Shantha K. L. , Pratap G. , Rao V. S. Bhaskar , Krishnamurti N. 
Published: April 2003

AbstractThe 1,6‐ and 1,7‐dihydroxy alkanes having chain lengths C13–C24 were synthesized in high purity by lithium aluminum hydride reduction of corresponding 6‐oxo and 7‐oxoalkanoic acids. These were then converted to 6‐hydroxy and 7‐hydroxy acrylic esters, respectively, and were characterized by infrared, 1H nuclear magnetic resonance, and mass spectroscopic methods.
High conversion polymerization of methyl methacrylate in the presence of n‐dodecylmercaptan
Authors: Madruga E. L. , Román J. San , Benedi P. 
Published: April 2003

AbstractThe kinetics of free‐radical homopolymerization of methyl methacrylate in the presence of different amounts of n‐dodecylmercaptan has been studied at 70°C. The introduction of n‐dodecylmercaptan in the reaction mixture modifies not only the onset and magnitude of the gel effect but also the limiting conversion with respect to the corresponding parameters for the homopolymerization of pure methyl methacrylate. The results obtained are qualitatively correlated with the current theories on the free radical polymerization at high conversion degrees.
Blends and interpenetrating networks of phenolic resins and polyamides
Authors: Yang T. P. , Kwei T. K. , Pearce E. M. 
Published: April 2003

AbstractBlends and interpenetrating networks of phenolic resins and polyamides were prepared. Control of miscibility was achieved by modifying nylon 6I through copolymerization and N‐alkylation. The phenolic resin was also modified by partial conversion of the hydroxy groups to cinnamyloxy groups. The phase behaviors of these blends and semi‐IPNs were investigated.
Phase behavior of blends of polycarbonate with partially miscible polymers
Authors: Kim Woo Nyon , Burns Charles M. 
Published: April 2003

AbstractPhase behavior of blends of bisphenol A polycarbonate (PC) with polystyrene (PS), poly(styrene‐co‐acrylonitrile) (SAN), poly(acrylonitrile‐butadiene‐styrene) (ABS), poly(methyl methacrylate) (PMMA), poly(ethylene terephthalate) (PET), and poly(butylene terephthalate) (PBT) has been investigated. Blends were prepared by screw extrusion and solution casting with weight fractions of PC in the blends varying from 0.90 to 0.10. From the phase diagram of the blends, it appears that PS, SAN, ABS, PMMA, PET, and PBT dissolve more in the PC‐rich phase than does PC in the PS‐, SAN‐, ABS‐, PMMA‐, PET‐, and PBT‐rich phases. Also, from the measured glass transition temperature (Tg) of the screw‐extruded blends and the solution‐cast blends, it appears that compatibility increases more in the PS‐, SAN‐, ABS‐, PMMA, PET‐, and PBT‐rich compositions than in the PC‐rich compositions. Composition‐dependent values of the polymer‐polymer interaction parameters (g12) of various blends were calculated and found to be from 0.034 to 0.053 for equal weights of each of the polymers with PC.
Surface characteristics of polydimethylsiloxane—poly(methyl methacrylate) block copolymers and their PMMA blends
Authors: Inoue Hiroshi , Matsumoto Akihiro , Matsukawa Kimihiro , Ueda Akira , Nagai Susumu 
Published: April 2003

AbstractTo draw a relationship between surface concentration of the siloxane segment and adhesion performance, surface properties of the polydimethylsiloxane—poly(methyl methacrylate) block copolymers(PDMS‐b‐PMMA) prepared via poly(azo‐containing siloxaneamide)s and their PMMA blends have been studied by measurements of FT‐IR spectra, water contact angle, ESCA spectra and 180° peel strength toward pressure‐sensitive adhesive tape. The water contact angles of the chloroform‐cast blend films increased abruptly with siloxane bulk concentrations, or siloxane contents, particularly, on the air‐side surfaces to reach almost 100° in low siloxane content. A marked increase of the contact angle was observed in the blends containing siloxane chain length (SCL) of longer than 2000. ESCA data evidently confirmed for these blend systems that the siloxane segments with low surface energy were accumulated or enriched mainly on the air‐side surface, and that, on the other hand, polar PMMA segments with high surface energy were oriented to the glass‐side surface and the inside of the films. This surface accumulation behavior of the siloxane segments reflected the 180° peel strength, as a measure of adhesion performance. The water contact angle and 180° peel strength were unequivocally correlated to the siloxane surface concentration estimated from ESCA data. Conversely, in the compression‐molded blend films made by a hydraulic press between a Teflon and a stainless steel plate, the extent of surface accumulation of the PDMS segment was lower than that of the chloroform‐cast films, suggesting lower degree of segment migration in hot‐press films, probably due to substrate surface energy and lower relaxation in the blend melts.
Surface modified polysulfone hollow fibers. III. Fibers having a hydroxide group
Authors: Higuchi Akon , Nakagawa Tsutomu 
Published: April 2003

AbstractPolysulfone ultrafiltration hollow fibers were chemically modified on the surfaces with propylene oxide and Friedel‐Crafts catalysts. A peak at 1.6 ppm was observed in H1‐NMR spectrum of the modified fibers at 45°C, while the peak was not observed at 27°C measurements. The peak was attributed to a hydroxide group from the peak shift at high temperature. Micro ATR spectra of the modified fibers also suggested existence of CH(CH3)CH2OH segments on those surfaces. The modified fibers showed 10–80% rejection of polyethylene glycol 6000 at feed concentration of 0.5 wt %, depending on the conditions of surface reaction, and were found to have smaller molecular cut‐off than nonmodified fibers. The fibers were also compared with modified fibers with propane sultone reported previously [A. Higuchi et al., J. Appl. Polym. Sci., 36, 1753 (1988)], which had negatively charged segments of CH2CH2CH2SO. Absorption of bovine serum albumin on the modified fibers was estimated to be less than the nonmodified fibers from permeation measurements. It is suggested that fibers having hydrophilic surfaces show better results of anti‐absorption of solutes than the nonmodified fibers.
Mössbauer studies of ferric chloride containing ethyl methacrylate‐n‐butyl methacrylate copolymer
Authors: Kapur G. S. , Brar A. S. 
Published: April 2003

AbstractEthyl methacrylate(EMA)‐n‐butyl methacrylate (nBuMA) copolymer containing anhydrous ferric chloride was prepared by free radical polymerization at 70°C. TGA studies show that the addition of ferric chloride increases the thermal stability of the copolymer. Mössbauer studies of the copolymers showed the presence of Fe3+ species only. Mössbauer studies of the copolymer heated at 150°C, 250°C, and 500°C for 1 h showed that during the thermal degradation, Fe3+ species are reduced to Fe2+ and then finally α‐Fe2O3 is formed. The mechanism of thermal degradation has been proposed on the basis of IR, TGA, and Mössbauer studies.
The effect of hexane treatment on the permeation of silicone‐coated polyethersulfone membranes
Authors: Chen Y. , Miyano T. , Fouda A. , Matsuura T. 
Published: April 2003

AbstractThe polyethersulfone membranes were cast from casting solutions including poly(vinyl pyrrolidone) additive. The membranes were further dried, silicone‐coated, and used for the permeation study with hydrogen and nitrogen gases. It has been found that solvent hexane which was included in the silicone rubber solution for surface coating increased the pore size on the membranes surface when poly(vinyl pyrrolidone) was present in the membrane. The above effect counteracted the pore size decrease by silicone coating, and, as a result, an H2/N2 permeability ratio of only 8.9 was achieved as compared with 28, which was obtained when the base polyethersulfone membrane was prepared from a casting solution without poly(vinyl pyrrolidone) additive.
Fast atom bombardment mass spectrometry of disaccharide polyether polyols
Authors: Viswanathan Tito , Toland Alan , Liu Rui‐Qin , Lay Jackson O. 
Published: April 2003

AbstractThe products resulting from the propoxylation of sucrose and lactose under alkaline conditions have been studied using FAB mass spectrometry. Soft desorption/ionization, using fast atoms, was expected to show intense protonated molecules for each component of the reaction mixture, thus allowing the extent of propoxylation to be examined under various conditions. However, it appears that addition of the FAB matrix, namely thioglycerol, prior to mass spectral analysis, resulted in alteration of the analyte via hydrolysis/dehydration, with protonated molecules appearing only for matrix/analyte reaction products, and not the original compounds which were to be examined. The resulting mass spectra, however, provided information regarding the extent of propoxylation and were consistent with results obtained by other researchers examining acetylated sugars using CI‐MS.
Preparation and some properties of hydrophilic membranes obtained by radiation grafting of methacrylic acid onto fluorinated polymers
Authors: Hegazy El‐Sayed A. , Taher N. H. , Ebaid A. R. 
Published: April 2003

AbstractHydrophilic membranes were prepared by direct radiation grafting of methacrylic acid (MAA) onto poly(tetrafluoroethylene‐perfluorovinylether) copolymer (PFA) and poly(tetrafluoroethylene‐hexafluoropropylene) copolymer (FEP) films followed by alkaline treatment to confer ionic character in the graft copolymer. Addition of 0.5 wt % FeCl3 to the monomer solution effectively inhibited the homopolymerization process and higher grafting yield was obtained. The graft copolymerization of MAA was carried out in presence of methanol/water mixture (30/70 wt %) in nitrogen atmosphere irradiation. The dependence of the grafting rate on MAA concentration was found to be 0.63 and 0.94 order for PFA and FEP films, respectively. This grafting system proceeds by the front mechanism in which the monomer diffuses through the already grafted layer formed initially. Some selected properties of the graft copolymers were investigated. It was found that the grafted membranes possess good mechanical, electrical, and hydrophilic properties which may make them promising in some practical applications.
Study on the compatibility of the blend of poly(aryl ether ether ketone) with poly(aryl ether sulfone)
Authors: Yu Xiaomei , Zheng Yubin , Wu Zhongwen , Tang Xinyi , Jiang Bingzheng 
Published: April 2003

AbstractPoly(aryl ether ether ketone) is found to be compatible with poly(aryl ether sulfone) at a blending temperature 310°C. There is a single glass transition temperature (Tg) for various compositions of the blend. The relationship ofTgwith composition obeys Gordon‐Taylor's equation, where the adjustable parameter k is 0.43. Thermodynamic interaction parameter χ12is estimated to be ‐0.001 according to Nishi and Wang's melting point depression equation. When the processing temperature is above 350°C, phase separation takes place as shown by a double mechanical loss tangent relaxations in the range of 100–280°C.