bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of sulfone‐modified poly(vinyl alcohol) and its application for permselective membrane of sulfur dioxide
Authors: Imai Kiyokazu , Shiomi Tomoo , Tezuka Yasuyuki , Takada Matsunori 
Published: April 2003

AbstractThe Michael type addition reaction of poly(vinyl alcohol) (PVA) with a series of vinyl sulfones, namely methyl vinyl sulfone, ethyl vinyl sulfone, and t‐butyl vinyl sulfone, was performed with NaOH as catalyst to produce 2‐(alkylsulfonyl)ethyl PVA derivatives. The high permselectivity of sulfur dioxide against nitrogen and oxygen was achieved through these sulfone‐modified PVA membranes.
Melt transcrystallization of polyethylene on high modulus polyethylene fibers
Authors: He Tianbai , Porter Roger S. 
Published: April 2003

AbstractA polytheylene composite was prepared and tested. It was consisted of a high‐density polyethylene (HDPE) matrix and uniaxial gel‐spun high‐modulus PE fiber. Aided by the similarity between matrix and fiber, transcrystallization of HDPE melt on the PE fiber surface was generated. Nucleating agents were not employed. The transcrystalline growth of HDPE on the PE fiber surface was found to consist of an inner and an outer zone. The inner zone, 2–3 μm thick, is composed of HDPE crystals nucleated on the PE fiber surface. Photomicrographs showed a well‐defined region of row‐nucleated HDPE on the surface of PE fiber. This means the fibrils of HDPE were found to grow out from the PE fiber axis and HDPE crystallites are oriented in planes perpendicular to the PE fiber axis. The fiber in the composite induced the transcrystalline growth of HDPE on the PE fiber surface at higher temperature than on cooling the melt. For 36 wt% fiber, the increase was 2.5°C, also resulting in ∼ 10% more crystals. Crystallization of a composite with 50 wt% fiber at 124°C involved two steps: The first a fast transcrystallization of HDPE on the PE fiber surface followed by the bulk crystallization of the HDPE.
Water–ethanol permseparation by pervaporation through photocrosslinked poly(vinyl alcohol) composite membranes
Authors: Hirotsu Toshihiro , Ichimura Kunihiro , Mizoguchi Kensaku , Nakamura Eiichiro 
Published: April 2003

AbstractWater–ethanol permselectivity was investigated by pervaporation through composite membranes which were prepared by coating photocrosslinkable poly(vinyl alcohol) containing pendant styrylpyridinium group (0.86–3.93 mol %) on porous films. These membranes were water‐permselective, and the selectivity was dependent on the state of membranes; namely, incorporation ratio of styrylpyridinium group on poly(vinyl alcohol), molecular weight of the base polymer, coating thickness of a photopolymer, etc. Photocrosslinkable styrylpyridinium group showed, of course, the ionic character by a pyridinium moiety to work on permseparation of water effectively as well as preventing the dissolution of membranes by crosslinking. Membranes based on the higher molecular weight poly(vinyl alcohol) (P = 1700) gave the higher permselectivity of water in general than those of lower molecular weight (P = 500) one. Swelling of the polymers reached 160%, and permeation rate through the membranes increased with the increase of swelling. Selective diffusion of water was found to take place in swelling, and to play a part in the water‐permseparation through the membranes.
The effect of spinning speed and drawing temperature on structure and properties of poly(ethylene terephthalate) yarns
Authors: Huisman R. , Heuvel H. M. 
Published: April 2003

AbstractFrom an industrial point of view, it is effective to have a relation between process conditions and resulting product properties. In practice there are many possible process conditions, whereas properties are generally interrelated in a complex way. Thus, there is a strong need for a physical understanding of the product properties in terms of process settings. This comprehension should also allow one to predict possible consequences for the properties when new process conditions become available. To obtain that physical understanding for the development of production processes of PET yarns, use has been made of a simple two‐phase model of crystalline and amorphous regions. As process parameters the spinning speed and the drawing temperature were chosen. As the drawing temperatures are only known as machine‐setting values, they are simply referred to as “low” and “high.” As mechanical properties the shrinkage, modulus, tenacity, and dynamic mechanical behavior are discussed.
Lyotropic liquid crystalline solutions of hydroxypropyl cellulose in water: Effect of salts on the turbidity and viscometric behavior
Authors: Suto Shinichi , Nishibori Wataru , Kudo Kazuhisa , Karasawa Mikio 
Published: April 2003

AbstractEffect of addition of salt on the viscometric behavior of the dilute or concentrated aqueous solution of hydroxypropyl cellulose (HPC) was determined by means of an Ubbelohde or a cone‐plate viscometer. That effect on the turbidity of the dilute system was also determined. As salts, NaCl, LiCl, and thiourea were chosen. The turbidity and viscometric behavior for the dilute system, and the viscometric behavior for the concentrated system were greatly affected by salt type and concentration. With increasing NaCl or LiCl concentration, the cloud point decreased, [η] showed a maximum, Huggins' constant k′ showed a minimum, and the shear viscosity for concentrated isotropic solutions showed a maximum. The 45 wt % solution with no salt showed a viscometric behavior which was characteristic of lyotropic liquid crystals; however, with increasing NaCl concentration, a critical temperature at which the shear viscosity showed a maximum with respect to temperature shifted to lower temperature. This behavior was due to an increase in the turbidity, not due to a phase transformation. On the other hand, an addition of thiourea did not affect so greatly the turbidity and viscometric behavior as an addition of NaCl or LiCl did. We speculated different actions of NaCl and thiourea.
Kinetics studies of solvent‐induced crystallization of drawn poly(ethylene terephthalate) by the in situ density measurement
Authors: Im Sung Soon , Lee Hyung Sick 
Published: April 2003

AbstractThe effect of draw ratios on the solvent‐induced crystallization (SINC) of poly(ethylene terephthalate) (PET) films was investigated. Dimethyl formamide (DMF) and dioxane were used as strongly interacting solvents. A newly devised in situ density measuring apparatus was applied to directly examine solvent peneration kinetics in PET. In this article, the density of PET films, which had a linear relation with crystallinity, was estimated rather than the degree of crystallinity. The solvent‐penetrated PET film was divided into three regions: a surface‐cavitated, a crystalline‐swollen, and an unpenetrated region, to determine the specific characteristics of the respective regions. It was found that the density in the internal region and the fraction of the surface‐cavitated region had a larger dependence on draw ratio than on treatment temperature. Also, the diffusion coefficients for the crystalline swollen region were calculated at various draw ratios and the morphological structure of the PET films was described.
Monitoring the cure of unsaturated polyester resins by pressure DSC and FTIR‐PLC
Authors: Yang Y. S. , Lee L. James , Lo S. K. Tom , Menardi P. J. 
Published: April 2003

AbstractA high pressure differential scanning calorimeter (DSC) and a Fourier transform infrared (FTIR) spectrometer with a prism liquid cell (PLC) were used to monitor the reaction kinetics of styrene‐unsaturated polyester resins at elevated curing temperatures and pressures. The thermal method is easy to perform but provides only an overall reaction exotherm. The spectroscopic method can detect the detailed reaction mechanism of copolymerizations. It is, however, less quantitative and the calculation is much more time‐consuming compared to the thermal analysis. Reactions of two unsaturated polyester resins with different molecular structure were measured by these two methods. Results showed that applying cure pressure on unsaturated polyester resins reduced the reaction rate but increased the final conversion. The styrene reaction was enhanced more than the polyester reaction at high curing temperatures.
Kinetics of multimonomer emulsion polymerization. The pseudo‐homopolymerization approach
Authors: Storti G. , Carrà S. , Morbidelli M. , Vita G. 
Published: April 2003

AbstractBy generalizing the Smith–Ewart theory, a system of polymer particle population balances is developed for describing the kinetics of emulsion polymerization processes involving any number of monomer species. Each population is characterized by the number of active radicals of each type present inside each particle, and described through a size distribution function. An approximation procedure is proposed for reducing the original system to that typical of homopolymerization processes, thus characterizing each population‐only through the overall number of radicals, without any significant loss of accuracy. The reliability of such “pseudo‐homopolymerization approach” is tested by comparison with polymer composition vs. monomer conversion experimental data for the ternary system acrylonitrile–styrene–methyl methacrylate.
Degradation mechanism and morphological change of PET by PEG–diamine
Authors: Kim Kap Jin , Ko Sohk Won 
Published: April 2003

AbstractThe aminolysis mechanism and morphological change were investigated with NMR, IR, GPC, density, and other physicochemical methods when the biaxially drawn PET film was aminolyzed with PEG–diamine at 130°C. By the aminolysis reaction, the PET chain end was capped with PEG chain as the following equation:
magnified image
Molecular weight showed a rapid decreasing tendency in the initial stages of the aminolysis reaction. The crystallinity, measured by density and IR methods, increased with the reaction time mainly due to the recrystallization of the amorphous PET chain promoted by better chain mobility of the PEG‐terminated PET. The fold period of the chain‐folded lamellar crystal formed through recrystallization was the same as that of the original PET lamellar crystal. It was found that 74% of all the capped PEG chains were located in the amorphous region, 18.4% at the initial point from which the recrystallized lamellar crystal began to grow, and the rest in the lamellar crystalline lattice.
A study on viscosity of suspensions
Authors: Chiu Wen‐Yen , Don Trong‐Ming 
Published: April 2003

AbstractFrom a simple kinetic viewpoint for the formation and rupture of links among primary particles, the pseudoplastic behavior of suspensions can be well described. At steady state, the formation and rupture of links reach a dynamic equilibrium, and the viscosity of suspension is proportional to the state of aggregates. It is assumed that the formation of links is due to the surface forces over particles, including van der Waals' force, and is independent of shear rate. The rupture of links is proportional to ṙm. Finally we get a very simple equation to predict the viscosity of suspension. With this simple kinetic viewpoint, the pseudoplastic behavior of suspensions composed of binary blends of monosize particles is also predictable.
Properties of bound water in poly(acrylic acid) and its sodium and potassium salts determined by differential scanning calorimetry
Authors: Haldankar Gautam S. , Spencer H. Garth 
Published: April 2003

AbstractThe thermal transitions occurring in poly(acrylic acid) and its sodium and potassium salts were investigated over a large range of water content using differential scanning calorimetry at temperatures below the normal melting temperature of water. The bound water was identified as nonfreezing (type I), freezing with a constant melting temperature (type II), and freezing with a melting temperature dependent on the water content (type III). The transition temperatures of the freezing states of the water were determined. Two constant melting temperatures were observed for the type II water in the sodium and potassium polyacrylates, while a single transition of this type was observed for poly(acrylic acid). The sodium polyacrylate absorbed more water in the nonfreezing state than the potassium polyacrylate, and both polyelectrolytes absorbed about three times as much water in this state as the nonionic poly(acrylic acid). The effects of water content on the occurrence of an exotherm at low temperature in the melting scans of the polyelectrolytes are described.
Homogeneous and heterogeneous copolymerization of styrene and sulfur dioxide using the (CH3)3COOH/SO2 redox system
Authors: Ali Sk. A. , Tsonis C. P. , Wazeer M. I. M. 
Published: April 2003

AbstractStyrene was copolymerized with sulfur dioxide in the presence of tert‐butyl hydroperoxide under homogeneous and heterogeneous conditions. The rate of copolymer formation decreases in the order emulsion, suspension, organic–aqueous, and organic solution. The rate also depends on reaction time, temperature, solvent, and initiator concentration. Several physical methods used to characterize these copolymers, including IR, 13C‐NMR, elemental analysis, viscosity, softening point, and isothermal aging. Analysis of the composition of the resulting copolymers revealed that there are on the average about two molecules of styrene per SO2 present on the copolymer chain. 13C‐NMR suggests that these copolymers are made up mostly of the MSM, SMM, and MMS triad monomer sequences whereas the SMS and MMM are present in small amounts. Characterization of polystyrene homopolymers shows that there is lack of stereoregularity in both homogeneous and heterogeneous polymerization systems.
The characterization of a poly(ethylene terephthalate)–poly(tetramethylene ether) multiblock copolymer via cross fractionation and size exclusion chromatography
Authors: Zhonge Xu , Ping Yuang , Jingguo Zhong , Erfang Jiang , Meiyan Wu , Fetters Lewis J. 
Published: April 2003

AbstractA poly(ethylene terephthalate)–poly(tetramethylene ether) multisegment block copolymer has been characterized by cross fractionation, where the individual fractions were then analyzed via size exclusion chromatography. The use of dual detectors (refractive index and ultraviolet) allowed both the compositional heterogeneities and molecular weight distributions to be evaluated. The SEC based molecular weights were supplemented by osmometric based molecular weights.
Properties of syndiotactic‐rich poly(vinyl alcohol) thin film in water. VII. Elastic behavior of swollen film in water through heating/cooling or cooling/heating cycles
Authors: Yamaura Kazuo , Watanabe Junko , Tanigami Tetsuya , Matsuzawa Shuji 
Published: April 2003

AbstractThe thermoelastic behavior for highly swollen films of syndiotactic‐rich poly(vinyl alcohol) (s‐PVA) was ascertained under loads in water through heating/cooling or cooling/heating cycles (in the range of 25–70°C). The s‐PVA films kept at the high temperature of 70°C behaved as a perfect elastomer through the cooling/heating cycle and had very low Young's modulus, 2–3.5 × 106 dyn/cm2. When highly swollen s‐PVA films were kept at lower temperatures below about 50°C for a long time, microcrystals were formed or propagated in the s‐PVA films and plastic deformation occurred in addition to elastic deformation through heating process. The microcrystalline growth and propagation at lower temperatures were supported by an increase in Young's modulus and a decrease in the molecular weight between junctions.
Acetylation of jute: Effects on strength, rot resistance, and hydrophobicity
Authors: Andersson Mona , Tillman Anne‐Marie 
Published: April 2003

AbstractJute cloth was acetylated with a limited amount of liquid acetic anhydride at 120°C. Weight gains of up to 20% were obtained. At a weight gain of 11%, achieved after a reaction time of 2 h, resistance to fungal attack was greatly improved. The cloth was also even in color, and the reduction in strength was minor. Tests on equilibrium moisture content and water uptake showed that the acetylated jute was much more hydrophobic than the unmodified material. It also shrank less when leached in water. Hence, dimensional stabilization was obtained.
Residual porosity in polymeric latex films
Authors: Balik C. M. , Said M. A. , Hare T. M. 
Published: April 2003

AbstractSolubility and diffusivity measurements of a probe gas (CO2), which has an inherently low solubility in the polymer, have been used to characterize residual porosity in polymeric latex films. Sorption isotherms resembling those of a glassy polymer were obtained, even though the glass transition temperature of the polymer was 1°C, about 30°C below the experimental temperature. Solvent cast films of the same polymer exhibited much lower solubilities, and followed the expected Henry's law behavior. CO2 solubility and diffusivity were found to decrease with aging time for the latex films, but did not quite reach the values of the solvent cast films, even after 75 days at room temperature. The sorption data could be described by the dual‐mode sorption model, which is commonly employed in the analysis of glassy polymer sorption isotherms. Estimates of the amount of porosity were made from the sorption data, and values ranging from 0.6–0.03% were obtained for latex films aged from 62 h to 75 days, respectively. Our results suggest that permeability differences noted by others for latex and solvent cast films of the same polymer are due to the substantial solubility differences for low‐solubility penetrants in these two types of films.
Oxidation of cellulose by ceric ion
Authors: Graczyk Tomasz 
Published: April 2003

AbstractDissolving pulp was oxidized by ceric ammonium sulfate in sulfuric acid medium under oxygen‐free argon. Initial rapid oxidation was followed by first‐order consumption of ceric ion. The rate of cellulose oxidation (−RCe) which was taken at the beginning of the first order consumption period, levelled off with an increase in the concentration of ceric ion. It was found that the −RCe was dependent on the concentration of cellulose in the second power. The rate of ceric ion consumption was a function of the available surface area of cellulose.
Effect of flow rate and temperature on crystallization kinetics, crystallinity index, and elastic modulus of PEEK
Authors: Mishra Ajit Kumar , Schultz Jerold M. 
Published: April 2003

AbstractDynamic, in situ wide angle X‐ray scattering (WAXS) studies of the melt crystallization of injection‐molded poly(ether ether ketone) (PEEK) have been carried out using an X‐ray diffractometer and a position‐sensitive detector. A test cell has been fabricated to fit inside the diffractometer and yet work as a complete injection molding apparatus. The rate of crystallization has been shown to increase with decreasing crystallization temperature and/or increasing flow rate in the mold. The crystallization rate decreases dramatically with increase in melt soak time at 400°C. The crystallinity index, which affects the stiffness, toughness, and fracture behavior of PEEK, has been measured under various processing conditions, by wide angle X‐ray scattering, so as to optimize the process parameters: molding time, mold temperature, melt temperature, soak time at melt temperature, and flow rate. It has been shown that the crystallinity and hence the elastic modulus increase with increase in crystallization temperature and/or flow rate. Chain orientation has been shown to be absent in the bulk of the injection‐molded specimens under normal molding conditions.
Transport models for swelling and dissolution of thin polymer films
Authors: Papanu J. S. , Soane (Soong) D. S. , Bell A. T. , Hess D. W. 
Published: April 2003

AbstractFundamental models have been developed to describe swelling and dissolution of glassy polymer thin films. The models account for solvent penetration by either Fickian or Case II diffusion mechanims. The convective flux due to local swelling as the solvent penetrates is included. Chain disentanglement at the polymer‐developer solution interface is scaled with the local solvent concentration and polymer molecular weight using reptation theory. The effective surface concentration during dissolution is estimated by applying thermodynamics of swollen networks to the entangled polymer. Swelling and dissolution of thin polymer films have direct application to microlithography. Various molecular and processing parameters affect the outcome of resist development. The utility of the models for selecting appropriate developer solvents, minimizing resist swelling, and providing a better understanding of the swelling and dissolution of resists is demonstrated.
The effect of hot‐wet draw ratio on the coefficient of friction of wet‐spun acrylic yarns
Authors: Gupta B. S. , El‐Mogahzy Y. E. , Selivansky Dror 
Published: April 2003

AbstractA series of wet‐spun poly(acrylonitrile‐co‐vinyl acetate) yarns that were hot‐wet stretched to a draw ratio range of 2.0 × −7.0 × were made for study of surface morphology and frictional characteristics. These yarns show an increase in draw ratio. The fiber to fiber coefficient of friction, measured parallel (line contact), and perpendicular (point contact), increases with draw ratio, giving an excellent correlation between orientation and friction. The effects of hot‐wet draw ratio on the surface structure and its frictional behavior are discussed.
Interaction of cation‐exchange membrane with polycation. II. Poly(N‐alkyl‐4‐vinylpyridinium halides)
Authors: Ohmura Nobuhiko , Kagiyama Yasuhiro , Mizutani Yukio 
Published: April 2003

AbstractThe effect of the hydrophile–lipophile balance (HLB) of poly(N‐alkyl‐4‐vinylpyridinium halides) (PAVP) on the interaction between PAVP and the cation‐exchange membrane was elucidated by using various alkyl groups: methyl, ethyl, octyl, and so on. In the electrodialytic concentration of sea water by using the membrane on which PAVP has been adsorbed or ion‐exchanged, the ratio of monovalent cations to total cations in the concentrated brine, β (Na+K), is almost same at the initial stage in species of PAVP. However, the deterioration ratio of β(Na+K) is smaller with decreasing HLB. In order to obtain the large value of β(Na+K), poly(N‐methyl and dodecyl‐4‐vinylpyridinium chloride) (PMDVP), was investigated. PMDVP, of which the ratio of pyridinium groups quaternized with 1‐bromododecane to total pyridinium groups (Qd) is about 40%, shows high initial value of β(Na+K) and its good durability.
Investigation of structure of polyacrylonitrile–polyprorole composite film
Authors: Bhat N. V. , Sundaresan E. 
Published: April 2003

AbstractThe structure of polyacrylonitrile–polypyrrole composite film, prepared using pyrrole in vapor and FeCl3 as catalyst, was investigated using IR spectroscopy, DTA/TGA, and resistivity measurements. The films showed improved thermal stability and electrical conduction. The strength of the composite film decreased as compared to pure PAN and the growth structures of polypyrrole could be seen.
Further experimental evidences of the compatibility of poly(vinyl acetate) with poly(ethyl methacrylate) and its dependence on the ratio of the molecular weight of the two homopolymers
Authors: Olayemi J. Y. , Yusuf A. K. 
Published: April 2003

AbstractUsing various fractions of poly(ethyl methacrylate) (PEMA) and poly(vinyl acetate) (PVAc) of very narrow molecular weight distribution, a very wide range of 2–120 of molecular weight ratio M¯ν PEMA/M¯ν PVAc, (M¯ν)r was obtained. Studies of some tensile mechanical properties of films of the blends produced from solution on mercury confirmed strong dependence of the improvements of PVAc properties for blend with 18% PEMA on (M¯ν)r, especially in the range 5 ≤ (M¯ν)r < 100. The density of the films of the blend was much higher than those of the individual polymers and increased monotonically with (M¯ν)r. Optical micrographs of the films of the blends showed interactions between the two polymers with 18% PEMA composition, which appears to be more intimate as (M¯ν)r increases, as further evidence of compatibility and miscibility of the two polymers.