bluuebunny/crossref_metadata_2025_split huggingface dataset:
Study on ketalization reaction of poly(vinyl alcohol) by ketones. VII. Reaction between poly(vinyl alcohol) and aromatic ketones and behavior of poly(vinyl ketal) in water
Authors: Nakamura Naofumi 
Published: April 2003

AbstractThe ketalization reaction of poly(vinyl alcohol) (PVA) by aromatic ketones, with dimeth‐ylsufoxide (DMSO) as solvent, under the presence of an acidic catalyst in homogeneous system, was carried out. The synthesis of poly(vinyl ketal) (PVKL) for the case of phenylacetone and benzylacetone was thus successfully performed, but for the case of acetophenone was performed only with a ketalization degree of a few molecular percent, and for the case of benzophenone it could not be performed at all. It seems that these different behaviors in synthesis are due to steric hindrance of the bulky side chain of ketones. The equilibrium constant at 40°C was ca. 0.12. in the case of phenylacetone and benzylacetone, and the value is somewhat higher compared with that of aliphatic ketones, but somewhat lower compared with the case of cyclic ketones. Because the heat of reaction is 7.5 kcal/mol in these two aromatic ketones, all ketalization reactions are considered to proceed by the same reaction mechanism. The rate of hydrolysis, contact angle, surface free energy, moisture regain, and water vapor permeability of PVKL films were measured. All results show the PVKL obtained from phenylacetone is nearly equal to PVKL obtained from methyl n‐butyl ketone. However PVKL obtained from benzylacetone shows different behavior compared with other ketones, because the side chain of benzylacetone is flexible and bulky. The hydrophobicity of PVKL seems to depend upon the kind of the original ketones and the flexibility of the side chain. © 1995 John Wiley & Sons, Inc.
Development of a gel‐counting technique for quantifying cleanliness of film‐grade resins
Authors: Huang Yi‐Bin , Wessel Thomas E. 
Published: April 2003

AbstractA novel gel‐counting technique was developed to precisely quantify the cleanliness of filmgrade resins. The technique involves cross‐polarization on stretched film and counting gels at various magnifications. By combining the gel‐count data and the resolution power of the microscope at these magnifications, one can obtain detailed gel size distribution in the resins. © 1995 John Wiley & Sons, Inc.
Effect of evaporation time on the pervaporation characteristics through homogeneous aromatic polyamide membranes. I. Pure water permeation and membrane characterization by sorption measurements
Authors: Yamasaki Akihiro , Tyagi R. K. , Fouda A. , Matsuura T. 
Published: April 2003

AbstractThe pervaporation of pure water through homogeneous aromatic polyamide membranes was investigated. The structure of the prepared membranes was controlled by varying the solvent evaporation times before the gelation step from 5 min to 240 min. The permeation flux of pure water decreased rapidly when the solvent evaporation time increased from 5 min to 30 min, and the decrease was rather moderate at higher evaporation times. Vapor and liquid sorption measurements were used to characterize the membranes. The amount of vapor sorption at a given relative pressure increased with an increase in the solvent evaporation time. The specific surface area of the membranes, calculated from the vapor sorption isotherm, increased with evaporation time up to 30 min, and remained constant thereafter. Liquid sorption volume, on the other hand, decreased monotonically with an increase in evaporation time. The formation of channels in the membrane is used to explain the morphology change during the solvent evaporation. The increase in the solvent evaporation time gradually increases the number of the channels in the membrane and decreases their average size. Good correlation was observed between the average size of the channels (represented by the ratio of specific volume to the specific surface area) and the parameters associated with pervaporation transport. © 1995 John Wiley & Sons, Inc.
Oxidative aging of thermoplastic polyimide films
Authors: Hinkley Jeffrey A. , Yue Jireh J. 
Published: April 2003

AbstractTwo linear polyimides were subjected to accelerated isothermal aging at temperatures between 300 and 400°C. Losses in toughness correlated well with changes in glass transition temperature (Tg) of the films, but not with weight loss. Both materials have extrapolated lifetimes of 100,000 h near their Tg's. © 1995 John Wiley & Sons, Inc.This article is a US Government work and, as such, is in the public domain in the United States of America.
Phenomenological description of strain rate and temperature‐dependent yield stress of PMMA
Authors: Povolo F. , Hermida Élida B. 
Published: April 2003

AbstractA constitutive equation to describe the yield behavior of poly(methyl methacrylate (PMMA) is useful not only from the technological point of view, but also for the comprehension of the nonlinear mechanisms acting in the material. In both compression and tension, the yield stress is usually represented as a function of the strain rate at different temperatures. In PMMA and other glassy polymers these curves are related by scaling, that is, they can be matched to form a master curve. Particularly in PMMA the temperature and strain rate dependence of the master curve has been characterized by two different models. The first involves two thermally activated rate processes, one acting only at high strain rates. The second model interprets the yield process as a cooperative movement of several independent structural units, all with the same activation energy. In this article it is demonstrated that only the second phenomenological model is correct because it provides a good fit to the master curve of PMMA both in compression and tension, and verifies the properties of a set of curves related by scaling. Moreover, it is pointed out that the first model leads to severe inconsistencies because it does not consider the nonlinear behavior of PMMA. Finally, the physical parameters obtained (internal stress, activation volume, and enthalpy) are compared with those given in the literature. © 1995 John Wiley & Sons, Inc.
Characterization of crosslinked polystyrene beads and their composite in SBR matrix
Authors: Cha Yoon‐Jong , Choe Soonja 
Published: April 2003

AbstractMonodisperse crosslinked polystyrene (PS) beads were prepared by a reaction of semibatch emulsion polymerization with styrene monomer, divinylbenzene (DVB) crosslinking agent, and potassium persulfate (K2S2O8) initiator in the absence of emulsifier. The glass transition temperature (Tg) and the mean diameter of the beads were increased from 100 to 135°C and from 402 to 532 nm, respectively, for an incorporation of 2–10 mol % DVB. Crosslinking density was also linearly increased with DVB content. Scanning electron microscopy (SEM) photographs of styrene–butadiene rubber (SBR) composite filled with various contents of PS beads revealed that PS beads are relatively well dispersed without changing the spherical shape of the beads in all ranges of compositions. In stress–strain analysis, elongation at break and tensile strength of SBR composite were increased with the bead content. Applicability of the PS beads as a filler in SBR matrix is tested by plotting Mooney–Rivlin or Guth–Smallwood equations. However, mechanical properties of the composite with the beads were not so excellent as those of the composite with carbon black. Crosslinked PS beads are still tentative as a white color reinforcing filler on the SBR matrix. © 1995 John Wiley & Sons, Inc.
Study of cryostructuration of polymer systems. XI. The formation of PVA cryogels by freezing–thawing the polymer aqueous solutions containing additives of some polyols
Authors: Lozinsky V. I. , Solodova E. V. , Zubov A. L. , Simenel I. A. 
Published: April 2003

AbstractThe influence of the presence of some polyols in initial poly(vinyl alcohol) aqueous solutions on rheological and thermal properties of the cryogels, which were produced by the freezing–thawing method, was investigated. The polyol additives (cosolvents) were as follows: glycerol, propylene glycol, mono‐, di‐, and triethylene glycols, and oligoethylene glycols (PEG‐400 and PEG‐1000). It was shown that the introduction of glycerol, propylene, or ethylene glycols into the polymer solution resulted in a decrease of cryogel's shear modulus and fusion temperature, whereas the use of triethylene and higher ethylene glycol oligomers as cosolvents gave rise to an increase in the gel's strength and thermostability, and diethylene glycol exhibited a transitional influence. The possible mechanism of the action of reinforcing cosolvents is discussed. © 1995 John Wiley & Sons, Inc.
1H‐NMR studies of nonionic surfactant adsorption onto colloidal particles
Authors: Haggerty John F. , Roberts James E. 
Published: April 2003

AbstractProton Nuclear Magnetic Resonance (NMR) spectroscopy was used to study the adsorption of a hexadecyl‐terminated poly(oxyethylene) surfactant (nominal molecular weight of 1120 g/mol) onto hydrophobic polystyrene latex particles. The adsorption process affects the NMR response of the surfactant; various surfactant populations are represented by different features in the NMR spectra. An analytical method that utilizes surfactant systems with and without polystyrene latex particles was employed to determine the capability of NMR to observe adsorbed surfactant close to the particle surface. At the initial stages of surfactant adsorption, the oxyethylene chain interacts with the particle surface in a pancake‐like conformation. At higher surfactant concentrations, surfactant molecules are bound to the particle surface and also exist as micelles or are free in solution; approximately one‐third of the bound, 20‐unit oxyethylene chains are near the surface and are not detected by NMR. Using a theoretical monomer density profile, laser light‐scattering measurements, and the NMR results, an effective NMR detection limit of 1 nm from the particle surface has been calculated. © 1995 John Wiley & Sons, Inc.
Synthesis and characterization of core/shell ionomeric latexes. II. Surface analysis by X‐ray photoelectron spectroscopy
Authors: Arora A. , Daniels E. S. , El‐Aasser M. S. , Simmons G. W. , Miller A. 
Published: April 2003

AbstractIt is generally accepted that conductometric titration is a time‐dependent technique in the case of highly carboxylated latexes because of the changes in the structure of the particle surface resulting from the neutralization and the alkali swellability imparted by the carboxyl groups when titrated with an alkali. At high levels of neutralization, the diffusion of the hydroxyl groups into the shell will be much faster than at the lower levels of neutralization. Due to this changing rate of the diffusion of the hydroxyl groups into the highly alkaliswellable copolymer shell, the assignment of the carboxyl groups to the different sublevels inside the particle shell can, at best, be arbitrary. To overcome this handicap, x‐ray photoelectron spectroscopy (XPS or ESCA) was used to obtain the depth profile of methacrylic acid near the surface of the particles. It is expected that by accurately characterizing the surface loading of the carboxyl groups, it will be possible to control the microphase separation process of the system. Considering the high concentration of the carboxyl groups on the surface of the core/shell latexes prepared in this study, XPS experiments were conducted to obtain the depth profile of the carboxyl groups. Angle‐dependent XPS studies were performed on films derived from the core/shell latexes with different amounts of methacrylic acid in the shell layer in order to determine the compositional heterogeneities between the surface and subsurface layers. In addition, x‐ray photoelectron spectroscopy was used to study the changes in the surface composition of solvent‐cast core/shell latex films prepared in this study upon treatment with alkali solution. It was discovered that a large‐scale migration of the carboxyl groups could occur as a result of coulombic interactions. © 1995 John Wiley & Sons, Inc.
Characterization of the interphase in poly(divinylbenzene)/poly(N‐butyl acrylate) core/shell latexes by high‐resolution solid‐state NMR relaxation studies
Authors: Nelliappan V. , El‐Aasser M. S. , Klein A. , Daniels E. S. , Roberts J. E. 
Published: April 2003

AbstractPoly(divinylbenzene)/poly(n‐butyl acrylate) core/shell latexes were investigated using solid‐state 13C‐NMR. The (H)T1ρ relaxation time was found to be substantially affected by many of the seeded emulsion polymerization parameters, such as the core/shell ratio, the mode of addition of the second‐stage monomer, the addition rate of the second‐stage monomer, and the level of conversion of the seed latex at the time of addition of the second‐stage monomer. The existence of an interphase region between the core and shell polymers was detected. Maximum interphase region thickness was achieved when the butyl acrylate was added under starved conditions. The thickness of this interphase layer was calculated to be 5–7 nm based on a model proposed by McBriety.1 Solid‐state NMR was found to be an excellent spectroscopic technique to probe the interphase region in core/shell latexes. © 1995 John Wiley & Sons, Inc.
Simultaneous interpenetrating networks of a polyurethane and poly(methyl methacrylate). I. Metastable phase diagrams
Authors: Mishra V. , Du Prez F. E. , Gosen E. , Goethals E. J. , Sperling L. H. 
Published: April 2003

AbstractAny simultaneous interpenetrating network (SIN) synthesis contains three key events. These are gelation of polymer I, gelation of polymer II, and phase separation of polymer I from polymer II. Metastable phase diagrams of SINs are developed, in which the time occurrence of these three events is represented. A polyurethane/poly(methyl methacrylate) (PU/PMMA) system was chosen as a model. Polymerization kinetics were followed in situ for both PU and PMMA using Fourier Transform Infrared Spectroscopy (FTIR) with the aid of a heated demountable cell. Glass transitions of fully cured samples were determined by dynamic mechanical spectroscopy (DMS) and differential scanning calorimetry (DSC). Phase separation was determined by the onset of turbidity, and gelation of the first gelling polymer was determined by the sudden resistance of the system to flow. As a result, a metastable phase diagram was constructed for the four‐component SIN system (the two monomers and their respective polymers) as a tetrahedron in three dimensions with the two monomers and two polymers at the four apexes. Phase separation and gelations of the two polymers are indicated by various surfaces. These surfaces intersect at lines and curves, representing unique conditions of an SIN synthesis, e.g., simultaneous gelation of both polymers, or simultaneous phase separation and gelation of polymer I, etc. These conditions are critical in terms of the development of the SIN morphology, dividing the reaction space into specific regions. Finally, it is shown how the tetrahedron diagram helps visualize the course of the three key events during SIN synthesis, and provides direction for controlling them. © 1995 John Wiley & Sons, Inc.
Thermal characteristics of energetic polymers based on tetrahydrofuran and oxetane derivatives
Authors: Liu Ying‐ling , Hsiue Ging‐ho , Chiu Yie‐shun 
Published: April 2003

AbstractThermal characteristics and decomposition behaviors of energetic polymers based on oxetane derivatives, 3,3'‐bis(azidomethyl)oxetane (BAMO), 3‐azidomethyl‐3'‐methyloxetane (AMMO), 3‐nitratomethyl‐3'‐methyloxetane (NMMO), and 3,3'‐bis(ethoxymethyl)oxetane (BEMO), were studied by means of differential scanning calorimeter (DSC) and thermogravimetric analyzer (TGA). These polymers were found to exhibit low glass transition and large decomposition onthalpies which were brought about by the attached azide (N3) and nitrato (ONO2) groups. The decomposition enthalpies depended on the types and contents of the energetic substituents. The NMMO‐based polymers exhibited relatively higher decomposition enthalpies and less thermal stability than the others. Furthermore, the thermal stability of the polymers was further improved by partial curing treatment. These results reveal that these polymers are potentially useful for application in energetic propellant binders. © 1995 John Wiley & Sons, Inc.
Study of reverse osmosis separation and permeation rate for sulfonated poly(2,6‐dimethyl‐1,4‐phenylene oxide) membranes of different ion exchange capacities
Authors: Hamza Ali , Chowdhury Geeta , Matsuura T. , Sourirajan S. 
Published: April 2003

AbstractThe reverse osmosis performance of thin‐film composite membranes prepared from sulfonated polyphenylene oxide polymer with different ion‐exchange capacities was studied using various electrolyte solutes. The effect of the solvent used for the preparation of the polymer solution for surface coating was also studied. It was found that the preparation of thin‐film composite membranes with high selectivities and high fluxes was possible by adjusting properly the ion‐exchange capacity and the solvent. It was also found that the membrane performance was governed primarily by the ion‐exchange reaction between the solute cation and the proton in SO3H and the Donnan equilibrium. © 1995 John Wiley & Sons, Inc.
Thermolysis of polystyrene
Authors: Simard Y. D. M. , Kamal M. R. , Cooper D. G. 
Published: April 2003

AbstractStyrene was recovered from polystyrene (molecular weight of 138,000) by thermolysis in a nitrogen atmosphere at temperatures between 368 and 407°C. The results were independent of the initial weight of polystyrene, which was varied between 30 and 480 g. Up to 90% of the polystyrene was converted to liquid products. The liquid products had a styrene concentration as high as 90% and the styrene yield increased with temperature. Above 390°C, the residue left in the reactor (less than 30% of initial polystyrene charge) consisted mainly of styrene monomer, dimer, and trimer (MW of 190). The kinetics support a first‐order reaction with regard to the rate of production of volatiles. The activation energy was estimated to be 166.5 kJ/mol. © 1995 John Wiley & Sons, Inc.
Gas transport in poly(vinyl‐p‐isopropylbenzoate): Comparison and correlation with some other poly(vinyl esters)
Authors: Hirose Takuji , Mizoguchi Keishin , Terada Katsuhiko 
Published: April 2003

AbstractGas permeability in poly(vinyl‐p‐isopropylbenzoate) (PVp‐i‐PrB) was determined by a timelag method. The transport properties were discussed from comparison with the permeability data of other poly(vinyl esters), which were studied previously. All these polymers are structurally related, and the size of a side group or the position of its substituent was changed systematically. The isopropyl group of PVp‐i‐PrB is attached at the para position of a phenyl ring and is the largest in size. As a result gas diffusivity and therefore permeability were increased. The effect of the substituent on gas diffusivity was explained as it increases the interchain and intrachain distances. The discussion was supported from the comparison of the density data between PVp‐i‐PrB and other poly(vinyl esters). The diffusion coefficients of six glassy poly(vinyl esters) were correlated at their Tg and good correlations were shown to the free volume and its fraction. On the other hand, gas solubility was little affected by the change of an alkyl group on a phenyl ring. The solubility data of PVp‐i‐PrB and poly(vinyl benzoate) were shown to be clearly correlated with the critical properties of the penetrants. © 1995 John Wiley & Sons, Inc.
Structure–property relationship in fibers spun from poly(ethylene terephthalate) and liquid crystalline polymer blends. I. The effect of composition and processing on fiber morphology and properties
Authors: Petrović Zoran S. , Farris Richard 
Published: April 2003

AbstractPoly(ethylene terephthalate) (PET) matrix was modified by blending with a specially prepared thermotropic liquid crystalline polymer (TLCP), in the hope to make the in situ composite during fiber spinning. It has been found that the TLCP did not fibrillate in the PET matrix at any concentration under given processing conditions, although it did in the polycarbonate matrix. This was explained by the low interaction parameter (low surface tension) and partial degree of mixing of PET and TLCP. The TLCP was an excellent processing aid even at very low concentrations, but it had an adverse effect on the strength of highly drawn fibers. The modulus of both undrawn and highly drawn fibers increases slightly with increasing TLCP concentration. © 1995 John Wiley & Sons, Inc.
Tri‐n‐Butylborane oxide‐initiated homopolymerization of vinyl monomers containing cyano or isocyanato groups
Authors: Chappelow Cecil C. , Pinzino Charles S. , Byerley Thomas J. , Eick J. David 
Published: April 2003

AbstractHomopolymers of 2‐isocyanatoethyl methacrylate, ethyl α‐cyanoacrylate, and ethyl α‐is‐ocyanatoacrylate were prepared in tetrahydrofuran at 22 to 25°C using tri‐n‐butylborane oxide as a free radical initiator. Additionally, ethyl α‐isocyanatoacrylate was homopolymerized using 2,2′‐azobis(2‐methylbutyronitrile) as the initiator. Homopolymers were characterized by photoacoustic FT‐IR, DSC, and elemental analysis. © 1995 John Wiley & Sons, Inc.
Surface grafting of polymer onto carbon thin film
Authors: Tsubokawa Norio , Ueno Hiroshi 
Published: April 2003

AbstractThe surface grafting of polymers onto carbon thin film deposited on a glass plate was achieved by two methods: the graft polymerization initiated by initiating groups introduced onto the surface; and the trapping of polymer radicals by surface aromatic rings of the thin film. It was found that the radical and cationic graft polymerization of vinyl monomers are initiated by azo and acylium perchlorate groups introduced onto the surface, respectively, and the corresponding polymers are grafted onto the surface: the surface grafting of polymers were confirmed by the contact angle of the surface with water. In addition, the anionic ring‐opening alternating copolymerization of epoxides with cyclic acid anhydrides was found to be initiated by potassium carboxylate groups on the carbon thin film to give the corresponding polyester‐grafted carbon thin film. On the other hand, polymer radicals formed by the decomposition of azo polymer, such as poly(polydimethylsiloxane‐azobiscyanopentanoate) and poly(polyoxyethylene‐azobiscyanopentanoate), were successfully trapped by the surface aromatic rings of carbon thin film and polydimethylsiloxane and polyoxyethylene were grafted onto the surface. © 1995 John Wiley & Sons, Inc.
Investigation on suitability of poly(urethaneimides) as biomaterials
Authors: Masiulanis B. , Całusiński G. , Marjański W. , Kotschy M. , Jurkowski P. , Góralczyk B. , Staniszewska‐Kuś J. , Solski L. , Krzemień‐Dabrowska A. 
Published: April 2003

AbstractThe mechanical properties of poly(urethaneimides) (PUI) were compared with known biomedical polyurethanes. The resistance of PUI to extraction with hexane and water and to sterilization with ethylene oxide or water vapor was stated. Water sorption and the permeability of water vapor, oxygen, and carbon dioxide through PUI foils were investigated. In blood compatibility, the PUI foils were similar to cellulose material Cuprophane, used in dialysis. Preliminary in vivo testing of PUI implanted in rats indicated good biocompatibility of this polymer. © 1995 John Wiley & Sons, Inc.