bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of fluoroelastomer networks. I. Infrared analysis
Authors: Theodore A. N. , Carter R. O. 
Published: April 2003

AbstractFluorocarbon compounds based on vinylidene fluoride copolymers and dihydroxy nucleophiles were prepared to determine the network forming structures of the cured materials. Previous attempts to achieve this goal consisted of model compound reactions, of prevulcanization events, and of materials cured under conditions only approaching industrial vulcanization conditions. The proposed structures derived from these studies could be different from the entities that will come in contact with alternate fuels such as methanol/gasoline blends when used in automotive applications. The evolution of the solid‐state chemistry during cure and the final network structure needed to be defined. Thus, infrared vibrational spectra for 25‐μm thick sections from key stages of processing were recorded. These spectra established directly, for the first time, that bisphenol‐AF (BPAF) serves as the crosslinker during cure. Additionally, persistent unsaturation is formed on the elastomer backbone after crosslinking. Curing for extended periods of time produces no observable effect on the network. Furthermore, postcuring reduces residual hydrofluoric acid in the compound and results in two new absorptions at 2851 and 2920 cm−1, indicative of amorphous regions of polyvinylidene fluoride (PVF2). Although these findings help define the final network structure, there remain uncertainties about the pathway leading to the final structure. The data serve as input to understanding the fracture behavior and long term performance of this class of materials. It also could serve as a starting point for studies dealing with the enhancement of certain fluorocarbon properties such as low temperature behavior. © 1993 John Wiley & Sons, Inc.
Epoxidized linseed oil‐free fatty acids modified with substituted anilines as antioxidants and antirads for SBR vulcanizates
Authors: Younan A. F. , Al‐Kobtan A. F. , Badran B. M. 
Published: April 2003

AbstractEpoxidized linseed oil‐free fatty acids were reacted with aniline and three isomers of toluidine, anisidine, and chloroaniline in such a manner that the carboxylic groups remained free. The prepared adducts were evaluated as antioxidants and antirads for styrene butadiene rubber (SBR) vulcanizates. It was found that 2 phr of orthotoluidine, paraanisidine, orthochloroaniline, and aniline adducts were the best antioxidants and/or antirads. © 1993 John Wiley & Sons, Inc.
Thermal analyses of graft copolymers of poly (methyl methacrylate) main chain with poly (propylene oxide‐b‐ethylene oxide) graft chain
Authors: Lucas Elizabete F. , Porter Roger S. 
Published: April 2003

AbstractPoly(methyl methacrylate‐g‐(propylene oxide‐b‐ethylene oxide)) and poly (methyl methacrylate‐g‐(ethylene oxide‐b‐propylene oxide)), comprising chemically dissimilar sequences, exhibit intramolecular phase separation. These compositions have applications in coatings and as surface‐tension modifiers. This paper presents the thermal behavior of these graft copolymers: separate samples of the homopolymer and of the grafts were also analyzed to provide comparisons. The phase behavior has been analyzed by differential scanning calorimetry and by dynamic‐mechanical thermal measurements. Two glass transitions (Tg) are observed, caused by the partial incompatibility within the copolymers. The activation energy of the Tg relaxation process of the main chain is decreased by the graft chain. The influence of poly(propylene oxide‐b‐ethylene oxide) grafts on the thermal degradation of the poly(methyl methacrylate) (PMMA) main chain was studied by using thermogravimetric analysis. Prolysis of the graft copolymers occurs in three stages and begins on the graft chain and at a lower temperature than the pyrolysis of pure PMMA. Both the phase behavior and the thermal stability are found to depend sensitively on the composition of the copolymer. © 1993 John Wiley & Sons, Inc.
The influence of implantation conditions on the surface structure of polypropylene
Authors: S̆vorc̆ík V. , Rybka V. , Hnatowicz V. , Kvítek J. 
Published: April 2003

AbstractThe influence of the fluence and the energy of implanted F+ ions on the surface structure of polypropylene was studied by measuring the contact angle and UV‐visible spectra. With increasing ion fluence and energy, the polar component of the surface energy increases. At the same time, the number and the length of double‐conjugated bindings in the polymer also increase. With higher ion energy, an increasing number of conjugations are observed but their length remains unchanged. © 1993 John Wiley & Sons, Inc.
Evaluation of light‐scattering detectors for size exclusion chromatography. II. Light‐scattering equation selection
Authors: Jeng L. , Balke S. T. 
Published: April 2003

AbstractA new multiangle laser light‐scattering (MALLS) detector for size exclusion chromatography promises simultaneous measurement of both weight‐average molecular weight (Mw) and radius of gyration (rg) at each retention volume across the chromatogram. However, there are a variety of ways of interpreting the raw data to provide these results. This study examines variations of three different rearrangements of the basic light‐scattering equation. Data from a room temperature analysis of polystyrene and a high‐temperature analysis of polyethylene were used. The degree of fit of each equation to the data and the precision of the Mw and rg values are evaluated. To define precision, joint confidence regions (JCRs) were calculated and compared to simple confidence intervals based upon standard deviations in order to see the effect of interdependence of Mw and rg. Results showed that the Debye equation was superior to the inverse Debye equation (similar to the Zimm plot) for the interpretation of MALLS data. The effect of the quantity of data included in the regression model was also assessed. Use of only the most precise four detector angles was compared to use of a full set of 15 angles. Precision of weight‐average molecular weight values was found to be improved as the detector angle decreased because of the shortened extrapolation to zero angle. Precision at room temperature was much superior to that at high temperature. Use of simple confidence intervals was shown to provide only a fair approximation to the more accurate JCR. The “natural scatter” of data shown by the JCR generally shows the same trend as do plots in the literature of Mw vs. rg. Thus, it is concluded that JCRs should be more often calculated in light‐scattering studies in order to distinguish random scatter from meaningful correlations of these values. © 1993 John Wiley & Sons, Inc.
Synthesis of 3‐substituted‐2‐cyanoacrylates: Their evaluation as cross‐linkers in cyanoacrylate adhesive compositions
Authors: Vijayalakshmi V. , Rupavani J. N. , Krishnamurti N. 
Published: April 2003

AbstractAlkyl 2‐cyano‐2,4‐pentadienoates and alkyl 2‐cyano‐2,4‐hexadienoates were synthesized and characterized by spectroscopic methods. These were then evaluated as cross‐linkers in 2‐cyanoacrylate adhesive compositions to improve the heat stability of their adhesive bonds between various metal surfaces. © 1993 John Wiley & Sons, Inc.
The effect of different ammonium structure of quaternary ammonium resin on the electrochemical properties
Authors: Yang Chin‐Ping , Ting Chih‐Yang 
Published: April 2003

AbstractThe quaternary ammonium resin is synthesized by the ring‐opening reaction of an epoxy resin with a tertiary amine in the presence of a proton donor in the solution. This kind of resin can be dispersed in the water phase to form a conductible milky dispersion. In this study, different kinds of tertiary amines including the full‐alkyl group and the ester group‐containing or urethane group containing tertiary amine are reacted with DGEBA‐type epoxy resin to synthesize the quaternary ammonium resins. The resin characteristics and the electrochemical properties of its emulsion are investigated. In addition, properties of the emulsion prepared from tertiary amine salt resin are also measured for comparison. It is found that if the substituted groups of the ammonium structure of the quaternary ammonium resin are all alkyl groups, rupture voltage of the emulsion is very low. But when one of the substituted group contains an ester group or an urethane group, rupture voltage increases remarkably and the resin can be used for electrodeposition. Meanwhile, the electrodeposition theory of quaternary ammonium resin and its thermal cross‐linking reaction and the electrochemical properties of coemulsion prepared by mixing the quaternary ammonium resin and the tertiary amine salt resin are also discussed. © 1993 John Wiley & Sons, Inc.
Preparation of poly(2,6‐dimethyl‐1,4‐phenylene ether) (PPE)/epoxy laminate with functionalized PPE resin
Authors: Chao Herbert S.‐I. , Whalen Jana M. 
Published: April 2003

AbstractThermal expansion property at 288°C and methylene chloride resistance of poly(2,6‐dimethyl‐1,4‐phenylene ether (PPE)/epoxy laminate were found to be affected by the functionality on PPE resin. Nonlofting PPE/epoxy laminates were prepared with the PPE grafted with fumaric acid or the PPE having (di‐n‐butylamino) methyl substituent on the polymer backbone. Employing vacuum‐vented PPE extrudate or phenol‐redistributed PPE was also effective in improving the PPE/epoxy laminate properties. Attempts to preparing a real PPE/epoxy interpenetrating network as the matrix material for the laminate were also made by incorporating both PPE crosslinker and epoxy curing catalysts in the same formulation. © 1993 John Wiley & Sons, Inc.
Thermal conductivity of a polymer composite
Authors: Agari Y. , Ueda A. , Nagai S. 
Published: April 2003

AbstractA prediction equation for thermal conductivity of polymer composites reported in our previous papers has been revised in terms of two view points: (1) estimation of thermal conductivity of a composite using an idea of reduced thermal conductivity; and (2) the effect of ease in forming conductive filler chains on thermal conductivity is related to the CVF value in electric conductivity of the composite. The new equation was confirmed to be adaptable to thermal conductivities of varieties of polymer composite systems filled with spherical or irregular fillers. The equation was also considered to explain thermal conductivity of polymer composites filled with fibers. Further, it was found that thermal conductivities of fiber composites can be estimated by introducing a factor of the CVF value or aspect ratio (L/D) into the new equation. © 1993 John Wiley & Sons, Inc.
Physical properties of 2‐hydroxyethyl methacrylate‐grafted silk fibers
Authors: Tsukada Masuhiro , Freddi Guiliano , Monti Patrizia , Bertoluzza Alessandro , Shiozaki Hideki 
Published: April 2003

AbstractThis paper deals with the physical properties of silk fibers grafted with 2‐hydroxyethyl methacrylate (HEMA). Both tensile strength and elongation measured in the dry and wet states gradually decreased with increasing weight gain. The initial modulus of the grafted silk fibers in the dry state sharply increased in the weight gain range of 0–16%, then decreased to a lower value than the reference untreated sample. The refractive indices parallel and perpendicular to the fiber axis decreased, though the former showed a steeper slope. Accordingly, birefringence and isotropic refractive index also decreased, suggesting a lower degree of crystallinity and molecular orientation of grafted silk fibers. DSC, TMA, and TGA curves of the HEMA‐grafted silk fibers indicated an increased higher thermal stability of silk fibers due to the HEMA grafting. The dynamic mechanical measurements showed that the thermally induced molecular movement of both amorphous and crystalline domains of silk fibers was enhanced by HEMA grafting. X‐ray diffraction curves, however, implied that the crystalline structure of the silk fibroin remained unchanged regardless of HEMA polymerization. The introduction of HEMA polymer in silk fibers was evidenced by the infrared spectra, exhibiting the absorption bands characteristic of either the grafted HEMA polymer and the fibroin molecules with ordered β structure. © 1993 John Wiley & Sons, Inc.
Kinetics of epoxy resins formation from bisphenol‐A, tetrabromobisphenol‐A, and epichlorohydrin
Authors: Gao Jungang 
Published: April 2003

AbstractThe kinetics of formation of epoxy resins derived from bisphenol‐A, tetrabromobisphenol‐A, and epichlorohydrin under stoichiometric conditions was considered. The kinetics of reaction was studied by taking into account the consumption of the added alkali and epoxide group of epoxide oligomers. The obtained results satisfactorily explained that the reactivity of bisphenol‐A with epichlorohydrin is higher than that of tetrabromobisphenol‐A. The rate of dehydrochlorination of chlorohydrin ether in the presence of alkali and water is much higher than that of the rate of condensation of phenolic hydroxyl group with epichlorohydrin. The apparent reaction order of phenolic groups with epichlorohydrin and terminal epoxide groups in the oligomer are second order. The rate constants and reaction activation energy were determined. The results are discussed. © 1993 John Wiley & Sons, Inc.
The mechano‐sorptive behavior of flexible water‐blown polyurethane foams
Authors: Dounis Dimitrios V. , Moreland J. Cal , Wilkes Garth L. , Dillard Dave A. , Turner Robert B. 
Published: April 2003

AbstractSamples of flexible water‐blown slabstock polyurethane foams were compressed under constant load to study the effects of cycling moisture content on creep behavior and compare this behavior with the creep response where either a constant high or low moisture environment existed at the same temperature. Three sets of foams were tested: (1) 4 pph water content slabstock foam; (2) 5 pph water content slabstock foam; and (3) 2 pph water content molded foam. As the moisture conditions were cycled from low to high humidity while maintaining constant temperature in an environmental chamber, the compressive strain increased in subsequent steps with larger increases observed during the desorption portion of the humidity cycling. All three sets of foams showed similar behavior at a given temperature. At a temperature of 40°C, the strain levels under cyclic moisture conditions surpassed those levels observed at the highest constant relative humidity. During the first absorption step, the creep level increased. During any subsequent absorption step, the creep level either increased very little or none at all. Finally, during any desorption step, the creep level increased. This overall phenomenon of enhanced creep under cyclic moisture levels is attributed to water interacting with the hydrogen bonded structure within the foam. These hydrophillic interactions, principally promoted within the hard segment regions due to high hydrogen bonding, are disrupted causing slippage and increased in strain. As the foam is rapidly dired, regions of free volume are induced by the loss of water thus causing further increases in strain Prior to the reestablishment of well ordered hydrogen bonding. Further support to this proposition was given by the results obtained at a temperature of 90° C where it is well known that hydrogen bonds are much more mobile. Here, the strain levels under cyclic moisture conditions were nearly the same as those under constant high relative humidity. Weakening of the hydrogen bonds by means such as increased temperature resulted in similar strain levels to those under cyclic moisture levels. © 1993 John Wiley & Sons, Inc.
Effect of γ‐irradiation and temperature on the structure of metal chloride treated poly(acrylamide)
Authors: Moharram M. A. , Rabie S. M. , Daghistani A. Y. 
Published: April 2003

AbstractThe gamma‐induced changes in the structure of Poly(Acrylamide) (PAAm) treated with metal chlorides were investigated by following the corresponding variations in their ultra‐violet spectra. Careful examination of UV spectra revealed that irradiation of the specimens results in the appearance of an absorption peak at 275 nm whose intensity depends on the applied dose and the nature of the metal ions. This band is ascribed to the formation of the carbonyl group. The results indicate that the dependence of the intensities of the band at 275 nm on the nature of the metal used provides strong evidence for the formation of metal polymer complexes. It was found that the pretreatment of PAAm with the appropriate concentration of ZnCl2, CoCl2, or NiCl2 reduces the effects of heating and the oxidation effects of γ‐irradiation. These results show that these metal ions can be used as stabilizers against thermal degradation of PAAm in the temperature range up to 160°C. © 1993 John Wiley & Sons, Inc.
Investigation of the formation of physical damage on automotive finishes due to acidic reagent exposure
Authors: White D. F. , Fornes R. E. , Gilbert R. D. , Speer J. A. 
Published: April 2003

AbstractAutomotive paints with clear‐coat surfaces can be physically damaged by exposure to acidic reagents produced in a smog chamber designed to reproduce real environmental conditions. Visual and reflectance microscopy observations show that deposition of material formed from the reaction of the clear coat and the reagent drop occurs on the paint surface after the drop evaporates to a critical size, with the greatest deposition occurring at the edge of the drop. This type of deposition suggests a free‐energy minimization process favoring the formation of stable nuclei at the reagent drop edge. With heating after the drop evaporation to simulate exposure to the sun, a damaged area containing sulfur that is in the shape of a circular ring is observed at the location of the deposits. The majority of the visual damage appears to result from an interaction between the deposit and the paint at elevated temperatures. Results from profilometry, scanning electron microscopy, and reflectance microscopy show that the damaged areas are ring‐shaped cracked blisters on the surface resulting from the clear coat separating into layers. © 1993 John Wiley & Sons, Inc.
Specialty polyurethane soft segments. IV. Reactions of aminated poly(propylene glycols) with isatoic anhydride
Authors: Harris Robert F. , Lopez Karen M. 
Published: April 2003

AbstractAlthough it has been reported that aminated poly(propylene glycols) react with isatoic anhydride to cleanly yield the corresponding o‐aminophenyl amide (II), this paper shows that a competing reaction leads to the formation of about 10% of the corresponding urea carboxylic acid (III). This impurity (unreactive toward polyisocyanates) limits the use‐fulness of (II) in urethane/urea polymers. A procedure has been developed to quantify (II) and (III). Based on the insight gained, a process has been developed to produce the corresponding o‐aminophenyl amide derivatives of aminated poly(propylene glycols) in a state of high purity (˜100%). A given aminated poly(propylene glycol) is added dropwise to a siurry of isatoic anhydride in an inert fluid (such as toluene or a previously prepared product) at a temperature (60–100°C) at which reaction is rapid. Local excesses of unreacted amine are minimized to prevent formation of urea carboxylic acid impurities. This process has been applied to the preparation of the corresponding derivatives of a variety of aminated poly(propylene glycols). © 1993 John Wiley & Sons, Inc.
Interpenetrating polymer networks from hydroxy‐terminated polybutadiene‐based polyurethanes and poly(methyl methacrylate)
Authors: Choudhary Veena , Gupta Rajni 
Published: April 2003

AbstractIsocyanate‐terminated urethane prepolymer was prepared by reacting 2 mol of tolylene diisocyanate (TDI) with 1 mol of hydroxy‐terminated polybutadiene (HTPB, mol. wt. = 3000) at room temperature (30 ± 1°C) in the presence of stannous octoate as the catalyst. Urethane prepolymer was subsequently mixed with 1,4‐butane diol: glycerol (6 : 1 ratio), methyl methacrylate (MMA), and ethylene glycol dimethacrylate (EGDMA) to give an interpenetrating polymer network. Stannous octoate was used as a catalyst to give network I, and azobisisobutyronitrile (AIBN), as an initiator to give network II. Different proportions of MMA were added to the prepolymer for studying the effect of composition on mechanical properties, thermal behavior, and optical properties. The mechanothermal behavior was analyzed using a dynamic mechanical thermal analyzer. Tensile strength and modulus decreased with decreasing MMA content, whereas percent elongation at break increased. Thermal stability of the sample increased with increasing urethane content. © 1993 John Wiley & Sons, Inc.
Synthesis of poly(chloroprene‐co‐isobutyl methacrylate) and its compatibilizing effect in polychloroprene/poly(isobutyl methacrylate) blends
Authors: Park Choon Keon , Ha Chang Sik , Lee Jin Kook , Cho Won Jei 
Published: April 2003

AbstractA copolymer of chloroprene (CP) and isobutyl methacrylate (iBMA) [poly(CP‐co‐iBMA)] was prepared in benzene by radical copolymerization. For comparison, the graft copolymer of iBMA onto polychloroprene (CR) [poly(CR‐g‐iBMA)] was also prepared. The glass transition temperature of the poly(CP‐co‐iBMA) was about −32.4°C. The monomer reactivity ratios determined by the Finneman‐Ross method were given as r1 (CP) = 1.80 and r2 (iBMA) = 0.74 in the copolymerization of CP and iBMA, respectively. Miscibility of blends of CR and poly(isobutyl methacrylate) (PiBMA), prepared by casting from tetrahydrofuran (THF) solution, was investigated by their glass transition temperature behaviors and morphologies. Although the blends of CR and PiBMA were incompatible, the addition of poly(CP‐co‐iBMA) or poly(CR‐g‐iBMA) enhanced miscibility between the two base polymers. It was found that the extent of partial miscibility becomes larger when adding poly(CP‐co‐iBMA) than poly(CR‐g‐iBMA) as a third component to the CR/PiBMA blend of 50/50 wt % composition. © 1993 John Wiley & Sons, Inc.
Some filler effects on cross‐linking of unsaturated polyesters
Authors: Paauw M. , Pizzi A. 
Published: April 2003

AbstractThe effect of five fillers on the cross‐linking macro‐and microcharacteristics of simple unsaturated polyester resins was investigated by differential scanning calorimetry (DSC), reactivity tests, and gel time tests. Glass beads and silica flour appeared to have little influence on the cross‐linking reaction of the resin itself, their effect being comparable to mere dilution of the resin. Kaolin presented some interaction with the resin due to its absorption characteristics and acid groups. Reground polyester/glass fiber powder and especially wood flour appeared to present clear chemical interactions with the curing behavior of the resin. Wood flour, in particular, was shown by DSC analysis to strongly co‐react with the resin during cross‐linking and altered markedly the resin enthalpy change and energy of activation during curing. The wood flour component causing the altered behavior of the resin appears to be lignin. DSC analysis of resins filled with three different types of isolated lignins indicated that this wood flour component reacts in a heterogeneous phase reaction with the resin during cross‐linking. It appears that it is the lignin unsaturated carbon–carbon double bonds at the polyester/wood flour and at the polyester/lignin interphases that are likely to co‐react by heterogeneous phase radical cross‐linking with the polyester resin and styrene unsaturation, markedly changing the resin curing behavior. © 1993 John Wiley & Sons, Inc.