bluuebunny/crossref_metadata_2025_split huggingface dataset:
Physical and surface properties of aqueous solutions of polyvinyl alcohols having an n‐alkylthio end group
Authors: Sato Toshiaki , Okaya Takuji 
Published: April 2003

AbstractThe polyvinyl alcohols (PVAs) having a n‐alkylthio end group of 10 through 16 carbon atoms were found to associate in the dilute aqueous solutions through hydrophobic interaction. From the apparent number‐average molecular weight with vapor pressure osmometer, the PVAs having an n‐dodecylthio and an n‐hexadecylthio group at one end were calculated to associate by about five and three molecules, respectively. The aqueous solutions of the PVA having an n‐dodecylthio group at one end showed much higher viscosity compared with the PVA having a hydroxyethylthio group at one end (HOCH2CH2S—PVA) in low concentration regions of below 10 wt % due to the association of the n‐dodecyl end group. Surface tensions of the aqueous solutions of the PVAs having an n‐alkylthio group at one end (n‐CnH2n+1S—PVA) showed almost the same value, which was slightly smaller than that of HOCH2CH2S—PVA, at 4 and 6 of carbon atoms, lowered with an increase in the number of carbon atoms above 8, showed minimum at 12 and then increased at 16 and 18. In the emulsion polymerization of vinyl acetate, n‐CnH2n+1S—PVAs of 10 through 18 carbon atoms acted effectively as a protective colloid.
Chemorheology on simultaneous IPN formation of epoxy resin and unsaturated polyester
Authors: Lin Mu‐Shih , Chang Reui‐Je 
Published: April 2003

AbstractStudy of the simultaneous interpenetrating polymer network (IPN) between diglycidyl ether of bisphenol‐A (DGEBA) and unsaturated polyester (UP) was carried out at ambient temperature. Fourier transform infrared (FTIR) spectroscopy was employed to investigate the intermolecular H‐bonding and functional group changes. Viscosity changes due to H‐bonding and crosslinking were examined with a Brookfield viscometer. Gelation time was measured by a Techne gelation timer. Complexation between Co(II) (the promoter for UP cure) and diamine (the curing agent for DGEBA) was detected with UV‐visible spectrometer. Experimental evidence revealed that intermolecular interactions were observed in systems such as DGEBA/UP, DGEBA/diamine, Co(II)/diamine, DGEBA/uncured UP, and UP/uncured DGEBA. All such interactions had measurable effects on the curing behaviors for both networks, as were indicated by the viscosity changes and gelation time. The IPNs thus obtained were further characterized with rheometric dynamic spectroscopy (RDS) and differential scanning calorimetry (DSC). Partial compatibility between UP and DGEBA networks was evidenced from a main damping peak with a shoulder near glass transition temperature (Tg) for lower UP content; while at higher UP content, only a main damping peak near Tg was observed. DSC revealed a broad glass transition for all IPNs. The resultant IPN materials were all transparent. © 1992 John Wiley & Sons, Inc.
The interaction of poly(methyl methacrylate) and chromium chloride: Transfer of methyl groups from the ester to the main chain
Authors: Beer Rudolfo Scott , Wilkie Charles A. , Mittleman Martin L. 
Published: April 2003

AbstractThe interaction of transition‐metal halides with poly(methyl methacrylate) (PMMA) has been studied in the past and methyl halides are always observed as a product of the reaction. When CrCl3 is used as an additive for PMMA, only traces of methyl‐containing products are seen and these only at quite high temperatures. The principal volatile products consist of carbon dioxide, carbon monoxide, and monomer, while the nonvolatile residue contains a multitude of methylene and methine carbons. A mechanism is invoked by which the ester methyl is transferred to the polymer backbone in a concerted process.
Preparation and properties of liquid crystalline alkyd resin with para‐hydroxybenzoic acid mesogenic side chain
Authors: Chiang Wen‐Yen , Yan Chun‐Shyurng 
Published: April 2003

AbstractLiquid crystalline (LC) alkyd resins with mesogenic side chains are prepared with the following three methods: (a) grafting p‐hydroxybenzoic acid (PHBA) to hydroxy‐terminated alkyd resin, (b) grafting PHBA to carboxyl‐terminated alkyd resin, and (c) grafting PHBA to an excess succinic anhydride‐modified alkyd resin. Dicyclohexylcarbodiimide (DCC) is employed to react with formed water in promoting esterification of PHBA with alkyd at room temperature. Pyridine is used as a solvent, and the catalytic amounts of p‐toluene‐sulfonic acid (p‐TSA) is added to suppress side reaction and to promote esterification. Grafting efficiency (% GE) is estimated to range from 70 to 95%. The character of liquid crystallinity is imparted only when at least two or more aromatic units of PHBA are connected to form the rodlike mesogenic side chain. At present, we have found that LC alkyd resins have the following merits: the polymer solution viscosity is reduced; the coating's dry‐to‐touch time is reduced; and the coating film is both hardened and toughened and has excellent resistance to water and acid. © 1992 John Wiley & Sons, Inc.
Properties of UV‐curable polyurethane acrylates for primary optical fiber coating
Authors: Kim Han Do , Kang Seung Gu , Ha Chang Sik 
Published: April 2003

AbstractStudies have been made on the effects of the chemical structure of reactive urethane acrylate prepolymers and diluents (reactive monomers) and overall composition of the prepolymer/diluent on the properties of the UV‐curable polyurethane acrylates for primary optical fiber coating. We prepared several urethane acrylate prepolymers from two different isocyanates, 4,4′‐dicyclohexylmethane diisocyanate (HMDI) or isophorone diisocyanate (IPDI), and two different polyols, polybutadiene diol (PBD) or polypropylene oxide diol (PPG), and 2‐hydroxyethyl acrylate (HEA) with dibutyl tin dilaurate as a photoinitiator. UV‐curable coating materials were formulated from the prepolymers and 2,2‐dimethyl 2‐phenyl acetophenone as a photoinitiator with one of four different diluents such as 1‐vinyl 2‐pyrrolidone (VP), lauryl methacrylate (LMA), acrylic acid 2‐ethyl hexyl ester (AEHE), and acrylic acid n‐butyl ester (ABE). It was found that AEHE is the desirable diluent in the formulation of the primary fiber‐coating material. The desirable composition of PBD, when mixed PBD/PPG diols are used, should be about 50 wt % for optimum formulation. Most of the urethane acrylate prepolymers prepared in this study could be applied in the formulation of primary optical fiber coating and exhibited good properties of buffer functions, including low glass transition temperature, low modulus even at low temperature, say, below −40°C, high refractive index, and low viscosity. © 1992 John Wiley & Sons, Inc.
Synthesis and properties of uniform beads based on macroporous copolymer glycidyl methacrylate–ethylene dimethacrylate: A way to improve separation media for HPLC
Authors: Šmigol Vladimír , Švec František 
Published: April 2003

AbstractMonodisperse beads based on hydrolyzed macroporous poly(glycidyl methacrylate‐co‐ethylene dimethacrylate) for use as size‐exclusion HPLC packings were synthesized by the method of “activated” swelling of polystyrene seeds followed by a suspension polymerization of both methacrylates. Effects of the type and fraction of the swelling agent, inert porogenic solvent, and cross‐linking monomer on the uniformity of the particles, extent of the specific surface area, pore volume, pore size, and pore‐size distribution and chromatographic properties (size‐exclusion limit and column effciency) have been investigated. Trends leading to the synthesis of macroporous particles with predesigned properties for use in size‐exclusion high‐performance liquid chromatography in both aqueous and organic mobile phase were studied. © 1992 John Wiley & Sons, Inc.
Dynamics of the phase inversion process
Authors: Mchugh A. J. , Tsay C. S. 
Published: April 2003

AbstractAn analysis of the dynamics of phase inversion based on mathematical modeling and in situ experimental observations is presented. Calculations based on ternary diffusion models illustrate the effects of casting film composition, evaporation time, and film thickness on the precipitation time and resulting polymer film profiles, which correlate with observed final morphologies. An experimental method based on the use of dark ground optics, interface visualization, and reflected light illumination is used for in situ monitoring of the mass transfer and phase separation dynamics during the quench step. Observations on the systems water—dimethylsulfoxide cellulose acetate and water—dioxane—cellulose acetate show regions in the films corresponding to gel formation and growth, instabilities associated with finger formation, and homogeneous ternary diffusion. Data for the kinetics of the diffusion and gel front motions show that both propagate as the square root of time with rates dependent on the bath—film compositions. Examples of interface structures characteristic of deep quenching and nucleated droplet growth are also shown. Semiquantitative analyses in terms of the ternary models developed earlier and a phenomenological model for diffusion in the growing gel are used to explain the trends seen. © 1992 John Wiley & Sons, Inc.
Melt rheology and morphology of PP/SEBS/PC ternary blend
Authors: Gupta A. K. , Srinivasan K. R. 
Published: April 2003

AbstractMelt rheological properties of the ternary blend of isotactic polypropylene (PP), styreneethylene–butylene–styrene terpolymer (SEBS), and polycarbonate (PC), PP/SEBS/PC, are studied in a wide range of composition, such that PP is the matrix and SEBS and PC are the minor components, with the proportion of one varying from 0 to 30% at various fixed compositions of the other. The respective binary blends, PP/SEBS and PP/PC, studied as the reference systems for interpretation of results on the ternary blends yielded interesting new information about the morphology development and its correlation with melt rheological properties of these binary blends. The studies include the measurement of melt rheological properties on a capillary rheometer in the shear rate range 101–104 s−1 at a fixed temperature of 240°C. The data presented as conventional flow curves are analyzed for the effect of blend composition and shear rate on pseudoplasticity, melt viscosity, and melt elasticity, and role of each individual component is identified. Morphology of dispersed phases of these blends is studied through scanning electron microscopy of the cryogenically fractured and suitably etched surfaces. Variations of morphology with blend composition and shear rate showed interesting correlation with melt rheological properties, which are discussed in detail. An important finding of the morphological studies is that in the PP/SEBS/PC ternary blend the SEBS phase forms two types of morphologies depending on the blend composition and shear rate: (i) simple droplets and (ii) boundary layer at the surface of the PC droplets. © 1993 John Wiley & Sons, Inc.
Rate of swelling of sodium polyacrylate
Authors: Ogawa Ikuko , Yamano Hideki , Miyagawa Kinjiro 
Published: April 2003

AbstractThe kinetics of the swelling of sodium polyacrylate (NaPA), a hydrophilic polymer, was studied gravimetrically, by microscopic observation, and calorimetrically. The swelling process followed first‐order kinetics and the rate constant was of the order of 10−2 s−1. The gravimetric method, however, was not useful for kinetic studies. The rate constant was depressed by the addition of sodium chloride. The activation energy of the swelling was 46.0 ± 6.2 (kJ mol−1) and decreased with the increase in sodium chloride concentration. In acid solution, the activation energy was almost the same as that in water. The heat of the swelling was 196 ± 17 J g−1 and did not vary with the addition of sodium chloride. © 1993 John Wiley & Sons, Inc.
Novel catalysts for the ring‐opening metathesis polymerization of norbornene‐type monomers
Authors: Goodall Brian L. , Kroenke William J. , Minchak Robert J. , Rhodes Larry F. 
Published: April 2003

AbstractA novel family of metallate compounds has been developed for use in catalyst systems for the ring‐opening polymerization of dicyclopentadiene (DCPD) and other norbornene‐type monomers. Examples of these novel catalyst compounds are the organoammonium isopoly‐and heteropolymetallates. Applications of these metallates in combination with alkylaluminum‐type reducing cocatalysts are found in the production of both solution polymers, and cross‐linked resins from reaction injection molding (RIM). These catalyst systems have significant advantages over prior art catalysts. They are highly soluble in DCPD and other norbornene‐type monomers, thus eliminating the need for a reaction solvent. They also are insensitive to air and moisture, have unlimited shelf‐life in solution in norbornene‐type monomers, and do not function as Lewis acids. The chemistry of these catalyst systems is discussed, along with the benefits they provide to the properties of the final polymer products. © 1993 John Wiley & Sons, Inc.
Fourier transform infrared and 13C‐NMR spectroscopic characterization of model epoxy networks
Authors: Gallouedec F. , Costa‐Torro F. , Laupretre F. , Jasse B. 
Published: April 2003

AbstractModel epoxy networks based on a diglycidylether of bisphenol A (DGEBA) or of butanediol (DGEBU) and cured with different mixtures of monoamines and diamines were prepared to allow changes in cross‐link density. The choice of aliphatic or aromatic amines permitted assessment of the influence of network chain flexibility. Solid state 13C‐NMR spectra showed that no secondary reactions leading to the creation of ether linkage occur during the condensation reaction. Glass transition temperatures (Tg) and the temperatures of the maximum of the exothermic cross‐linking reaction (Texo) were determined. A rectilinear increase of Tg as a function of the density of cross‐links was observed for all the systems under study. Similarly, an increase in the stiffness of the backbone units resulted in an increase in Tg. Time‐temperature‐transformation (TTT) isothermal cure diagrams were constructed and infrared kinetics were performed at 90°C. Gelation and vitrification times were shown to be dependent on the nature of the amines used to create the network structure. © 1993 John Wiley & Sons, Inc.
Viscometric studies of starch‐g‐polyacrylamide composites
Authors: Kaur Inderjeet , Misra B. N. , Barsola Raghuvir , Singla Kiran 
Published: April 2003

AbstractComposites of starch‐g‐polyacrylamide, starch, and polyacrylamide have been prepared by gamma radiation‐initiated polymerization of acrylamide in the presence of starch in aqueous medium. The polymerization was studied as a function of the (i) amount of water (ii) monomer concentration, and (iii) total dose. The optimum conditions for maximum conversion of the monomer to homopolymer and graft copolymer have been evaluated. Percentage of grafting of polyacrylamide could not be determined precisely as both the homopolymer and the graft are soluble in common solvents and all attempts to separate the graft from the homopolymer were unsuccessful. However, the formation of the starch‐g‐polyacrylamide copolymer was confirmed by the turbidimetric studies using acetone as a nonsolvent. The products of polymerization of acrylamide in the presence of starch consisted of unreacted starch, starch‐g‐polyacrylamide, and polyacrylamide and is referred to as the composite. Acrylamide was also polymerized in the absence of starch using γ‐rays as means of initiation and the optimum conditions for maximum conversion of acrylamide to polyacrylamide have been evaluated. Viscosity behavior of the composite and polyacrylamide was studied in aqueous medium at 30±0.04°C. The reduced specific viscosity of the aqueous solution of acrylamide and the composite as well was found to increase with increasing dilution, the effect being more pronounced in the composite. This tends to indicate that both the homopolymer and the composite behave as polyelectrolytes. An attempt has been made to explain the polyelectrolytic behavior of the homopolymer and the composite. © 1993 John Wiley & Sons, Inc.
Adhesion of polyimide to silicon and polyimide
Authors: Jou Jwo‐Huei , Liu Chiung‐Hong , Liu Jong‐Min , King Jing‐Shin 
Published: April 2003

AbstractThe characteristics of the adhesions of polyimide to silicon and to polyimide and the autohesion of a polyimide blend have been investigated. As found, the peel strength of pyromellitic dianhydride–4,4′‐oxydianiline (PMDA–ODA) on silicon can be greatly improved by blending with 20 or 40% benzophenone tetracarboxylic dianhydride–p‐phenylene diamine (BPDA–PDA). Exposing in air for a 2 day period resulted in a serious deterioration in adhesion for the pure PMDA–ODA system, while in no deterioration for the blend systems. Regardless of adhesion or autohesion, the resulting peel strength decreased markedly with the increase of the curing temperature. It was also found that based on the same curing temperature the diffusion of NMP is much faster in the film of PMDA–ODA than in the blend containing 20% BPDA–PDA. Beside curing temperature, imide‐to‐imide compatibility seems to play an important role in affecting the adhesion characteristics. © 1993 John Wiley & Sons, Inc.
Silicone acrylates through the hydrosilation of polyacryloyloxy functional monomers with copolymers of dimethyl and hydrogen methylsiloxanes
Authors: Kokko Bruce J. 
Published: April 2003

AbstractSilicone acrylates, as possible electron beam (EB) curable release coatings for paper, were prepared by the platinum‐catalyzed hydrosilation of polyacryloyloxy functional monomers with copolymers of dimethylsiloxane and hydrogen methylsiloxane (PDMHMS). The hydrosilation of either 1,6‐hexanediol diacrylate (HDDA) or trimethylolpropane triacrylate (TMPTA) with PDMHMS occurs to only one of the 2 or 3 available olefinic groups, respectively, as long as excess monomer is present. The amount of excess monomer needed to prevent gelation during hydrosilation or subsequent storage in excess of 1 month appears to be dependent on the hydrogen methylsiloxane content of the PDMHMS. A release coating having excellent cohesive and adhesive strength on paper was obtained by the EB curing of the product of hydrosilation of TMPTA with a PDMHMS containing 4 mol % hydrogen methylsiloxane at a dose‐to‐cure of 2 Mrad, but the aged release force was excessively high. The poor aged‐release performance was likely due to dilution of the dimethylsiloxane content of the coating with excess monomer required to stabilize the silicone acrylate. © 1993 John Wiley & Sons, Inc.
Preparation of polycarbonate/metal salt gas separation membranes
Authors: Lai Juin‐Yih , Chen Shih‐Hsiung , Lee Mei‐Hsiu , Shyu S. S. 
Published: April 2003

AbstractPolycarbonate (PC) membranes possess high O2/N2 selectivity and mechanical strength, but have low gas permeability. In order to improve the pure PC membrane's gas permeability and selectivity of O2/N2, in this study we attempt to combine transition metal salts into the membrane to form a complex membrane. Tensile strength and elongation at break of the membrane are not significantly changed. The effect of casting solution composition and solvent evaporation time on morphology, gas permeability, and selectivity of O2/N2 of PC membranes are studied. The gas permeabilities of PC/DMF/Metals membranes are significantly improved, as compared to those of pure PC membrane. For example, an oxygen permeability of 137 cm3 (STP)‐cm/cm2‐sec‐cmHg and separation ratio of oxygen to nitrogen of 4.0 for PC/DMF/CuCl2 membrane with [PC/CH2Cl2]/[CuCl2/DMF] = 17/3 mL/mL, and CuCl2/DMF = 0.1 g/mL, can be obtained. The FT–IR spectra and elementary analysis suggest that there is interaction among metal, DMF, and PC. © 1993 John Wiley & Sons, Inc.
Effect of diethylene glycol (DEG) on the crystallization behavior of poly(ethylene terephthalate) (PET)
Authors: Patkar Mahesh , Jabarin S. A. 
Published: April 2003

AbstractThe effect of diethylene glycol (DEG) on the crystallization of poly(ethylene terephthalate) (PET) was studied under isothermal and dynamic conditions. The strain‐induced crystallization of PET and its relationship to DEG content was also studied. The samples were isothermally and dynamically crystallized in the differential scanning calorimeter (DSC). The thermograms were then analyzed to determine the kinetic parameters. Strain‐induced crystallization was studied by stretching samples at different strain rates. These samples were then annealed for various periods of time and quenched to room temperature. Birefringence and density were measured on the annealed samples. Results indicate that the DEG content reduces the rate of crystallization of PET when crystallizing from the melt, isothermally and dynamically. When crystallizing from the glassy state, the effects of DEG are not prominent. The mechanism of crystallization is not affected by the amount of DEG, within the range of DEG contents evaluated. In the case of strain‐induced crystallization, increased DEG content reduces the crystallinity of PET at intermediate strain rates, but at higher strain rates, the crystallinity is not affected by the DEG content. © 1993 John Wiley & Sons, Inc.
High‐temperature thermoplastic elastomers via the grafting reaction of polyarylate onto EPDM rubber
Authors: Dean Barry D. 
Published: April 2003

AbstractPolyarylate monofunctionally terminated with a 1,2‐dihydrobenzocyclobutene group undergoes thermally initiated grafting reactions onto ethylene/propylene/nonconjugated diene rubber via the Diels—Alder reaction between the diene (benzocyclobutene) and the dienophile (pendant unsaturation on the EPDM). Characterization of the graft copolymer(s) is presented as is the resultant thermoplastic elastomeric mechanical performance exhibited by the graft copolymers. © 1993 John Wiley & Sons, Inc.
The disintegration rate of traditional and chemically modified plastic films in simulated fresh‐ and sea‐water environments
Authors: Leonas Karen K. 
Published: April 2003

AbstractSix plastic films with varying chemical compositions in three different accelerated weathering environments were evaluated for disintegration. The films included two traditional films (LDPE and polystyrene), three with enhanced photodegradability (2% ECO and 10% ECO and LDPE with a vinyl ketone graft), and one with enhanced biodegradability (LDPE with 6% corn starch). The films were exposed to UVA‐340 bulbs to simulate sunlight while in fresh water, salt water, or no water conditions. Disintegration of the films was determined by monitoring the change in physical properties of tensile strength at break, elongation at break, and toughness at break at selected intervals throughout the exposure period. Both the chemical composition of the film and the exposure environment produced significant differences in disintegration rates. Two of the films with enhanced photodegradability (2% and 10% ECO copolymers) disintegrated more rapidly than did the other films in this study. The environment where no water was present resulted in the fastest disintegration rate for the films when compared with the fresh‐water environment. However, two films, LDPE and LDPE with 6% corn starch, degraded more rapidly in the salt‐water environment than in the other two environments due to the presence of oxidation catalysts in the water system. © 1993 John Wiley & Sons, Inc.