bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of sodium lauryl sulfate on the polymerization of acrylonitrile
Authors: Patel N. , Mohammed I. , Das B. N. , Sinha B. K. 
Published: April 2003

AbstractMicellar catalyzed polymerization of acrylonitrile using ceric(IV)–glycerol redox system in aqueous sulfuric acid solution in the presence of sodium lauryl sulfate (NaLS) has been studied. The polymerization experiments were conducted between 15°C and 25°C, under conditions where no oxidation of sodium lauryl sulfate by ceric ion would we expected. The rate of polymerization (Rp) increases with increasing concentration of NaLS. The rate of monomer (AN) disappearance was proportional to [AN]1.5 and [glycerol]0.5, but, however, Rp changes in a nonlinear manner with increase in Ce(IV) concentration in the presence of the surfactant. The rate of Ce(IV) disappearance was not proportional to its original concentration. The chain length of the polymer could not be determined viscometrically, as the polymer obtained in presence of NaLS was insoluble in organic solvents. The activation energy of this polymerization process was calculated by conducting the experiment at different temperatures. The infrared spectra of the polymers in the presence and absence of surfactant have also been examined.
Plasticizer transfer from plasticized PVC into ethanol–water mixtures
Authors: Messadi D. , Vergnaud J. M. 
Published: April 2003

AbstractThe transfer of plasticizer from compression‐molded sheets of plasticized poly(vinyl chloride) into ethanol–water mixtures was studied over the temperature range of 30–55°C. A simultaneous diffusion occurred for ethanol and water into polymer and for dioctylphthalate plasticizer from polymer into liquid. The concentration of ethanol transferred into the polymer was found to increase, rise to a maximum, and then decrease. Equations of diffusion in unsteady state were found to correlate well with experiments on plasticizer transfer, over the plasticizer concentration range of 25–50 wt %. Stirring, temperature, water concentration in ethanolic solutions, and plasticizer concentration were found to play important roles.
Investigation of thermal degradation of polystyrene by differential scanning calorimetry
Authors: Toh H. K. , Funt B. L. 
Published: April 2003

AbstractThermal degradation of polystyrene was performed in a differential scanning calorimeter under nitrogen atmosphere, and the glass transition temperature was measured continuously. From random chain scission kinetics and Tg‐molecular weight relationships, the rate constant for random scission was obtained. The rate constant was found to undergo a drastic change at a critical molecular weight (∽45,000), which corresponds to a similar observation in relaxation studies. A viscosity‐dependent mechanism for radical chain end termination is thus suggested.
Characterization of the imidization of the aromatic polyimide LARC‐160
Authors: Delos S. E. , Schellenberg R. K. , Smedley J. E. , Kranbuehl D. E. 
Published: April 2003

AbstractThe polyimide resin LARC‐160 was prepared from diethyl‐3,3′,4,4′‐benzophenone tetracarboxylate (BTDE), ethyl‐5‐norbornene‐2,3‐dicarboxylate (NE), and Jeffamine AP‐22. The imidization reactions of NE and BTDE were studied by HPLC, 13C‐NMR, and IR. NE imidizes slowly at 12°C; BTDE imidizes when the resin is heated above 100°C. Both imidization reactions proceed directly to the imide. Neither amic acid is present in significant quantities at any stage of the imidization reactions. The monomer mixture has been stored at 12°C for periods up to 14 months. The effects of resin aging at this temperature on the chemical composition of the resin monomer mixture and the imidized polymer formed on curing were investigated. Aging the resin monomer mixture has the effect of partially advancing the imidization reaction. Aging also results in the formation of slightly higher‐molecular‐weight polyimide chains after curing of the resin at 140 and 180°C. Bisnadimide (BNI) is observed as a major reaction product, regardless of resin age.
Glow discharge polymerization of trimethylvinylsilane and tetramethylsilane
Authors: Inagaki N. , Taki M. 
Published: April 2003

AbstractGlow discharge polymerizations of trimethylvinylsilane (TMVS) and tetramethylsilane (TMS) were compared. Vinyl groups in TMVS slightly contribute the polymer‐formation process only when glow discharge polymerization was performed at the W/FM parameter less than 500 MJ/kg. Elemental compositions of the polymers prepared from TMVS, which are rich in carbon content, shows strong dependence on operational conditions, the W/FM parameter; but the polymers from TMVS consist of the almost same chemical structures as those from TMS. Slight differences between the starting materials in chemical structure does not reflect on bulk properties of the formed polymers but on surface properties such as surface energy and adhesion.
Processable heat‐resistant polymers. VII. Synthesis and characterization of polyamideimide from N‐(p‐carboxyphenyl) trimellitimide and p,p′‐di(aminocyclohexyl) methane
Authors: Maiti Sukumar , Ray Atanu 
Published: April 2003

AbstractPolyamideimides were prepared either directly from N‐(p‐carboxyphenyl)trimellitimide and p,p′‐di(aminocyclohexy)methane (PACM‐20) by low temperature (<5°C) polycondensation in presence of thionyl chloride or by reacting the diacid chloride of N‐(p‐carboxyphenyl)trimellitimide and PACM‐20 at 30–70°C. The polymers were characterized by nitrogen analysis and IR spectra. The polymers are soluble in highly polar solvents such as DMF, DMAC, NMP, and m‐cresol. The solubility parameter was calculated from the Small's group contribution, which agrees well with the experimental value. The solution viscosity of the polymer is fairly stable against ageing. The Tg of the polymer calculated from the DTA curve is 270°C or even higher. Thermal analyses indicated that the polymer is fairly stable and only 5–6% weight loss occurs up to 350°C or 380°C. Dielectric constant, dielectric loss, and electrical conductivity of the polymer were also studied.
Effects of mineral oil on the rheological behavior of polystyrene melts
Authors: Bersted B. H. 
Published: April 2003

AbstractThe effects of mineral oil on the small strain rheological functions of polystyrene are shown to be simply related to the oil content and the rheological behavior for the neat material. Reduced variables, which are analogous to the effects of temperature, are found to successfully reduce the data for all levels of oil. The use and form of these reduced variables are shown to be predicted by the model of Bersted, which relates the rheological functions directly to the molecular weight distribution. The effects of the oil are argued to suggest that the mineral oil acts as a plasticizer for polystyrene.
Crystallization kinetics of poly(vinyl alcohol)
Authors: Peppas Nikolaos A. , Hansen Paula J. 
Published: April 2003

AbstractThe kinetics of crystallization of solvent‐free poly(vinyl alcohol) were investigated by isothermal crystallization at temperatures of 142–192°C, for up to 18 min. The crystallization isotherms were analyzed by Avrami's theory. The magnitude of the exponent n was almost constant (0.67–0.71) in the range of 142–182°C, increasing to 1.53 for crystallization at 192°C. Based on thermodynamic analysis of the isotherms and the crystallite growth rate, there are strong indications that crystallization of PVA is one‐dimensional. In the absence of water or other swelling agents, kinetic hindrances predominate due to the interactions of the hydroxyl groups. Therefore, the maximum attainable weight fraction of crystallized PVA is considerably lower than that of hydrated PVA samples. Additional parameters affecting the growth rate are discussed, including the degree of undercooling and the average chain length, as controlled by crosslinking.
Polymerization of butadiene with Co(acac)3–(i‐Bu)3Al–H2O catalyst
Authors: Yang W. L. , Hsu C. C. 
Published: April 2003

AbstractThe polymerization of butadiene in toluene using Co(acac)3–(i‐Bu)3Al–H2O catalyst system was studied. Presented are the effects of the addition order, aging time, and composition of catalysts on rates, polymer microstructure, and molecular weights. The polymerization was found to be initiated by the Co(acac)3‐hydrolized aluminum alkyl complex. The chain propagation proceeds according to a first‐order reaction with respect to monomer and active species and is a strong function of Al/H2O with an optimum ratio of 1.0, but independent of Al/Co. The nature of polymerization seems to change as Al/H2O increases from less than 1 to greater than 1. Transfer reaction is significant. From the kinetic data it was found that the termination reaction is most likely to be by combination.
On the curing kinetics of unsaturated polyesters with styrene
Authors: Cuadrado T. R. , Borrajo J. , Williams R. J. J. , Clara F. M. 
Published: April 2003

AbstractThe curing kinetics of a general purpose unsaturated polyester (UP) with styrene was studied by differential scanning calorimetry and dielectric capacitance measurements. Benzoyl peroxide was used as initiator. Results showed that there is a complete change in the phenomenological kinetics, in different temperature ranges. At low temperatures (70–90°C), the rate went through a maximum and then showed a first‐order decay. At high temperatures (100–160°C) a second‐order kinetics was suitable for all the conversion range. At T > 160°C another mechanism took place when the initiator amount was less than a critical value. From the changes in the dielectric capacitance it was inferred that the conversion rate of UP unsaturations followed a first‐order decay after a certain conversion, with an activation energy close to values reported for diffusion of UP radicals. Possible free radical mechanisms accounting for experimental observations are discussed.
Studies on moisture sorption in coir fibers (cocos nucifera L)
Authors: Kulkarni A. G. , Cheriyan K. A. , Satyanarayana K. G. , Rohatgi P. K. 
Published: April 2003

AbstractMoisture desorption characteristics in coir fibers have been studied at several temperatures (53°C, 68°C, 86°C, and 105°C) as a function of time. Moisture absorption at room temperature after heating to 53°C, 68°C, 86°C, and 105°C are also reported. The results indicate that the relation between percentage moisture loss (A) (moisture loss is the ratio of the difference between initial moisture and final moisture to initial moisture) and temperature (T°K) is of the type A = Aoe−B/T in the range of intervals studied. The constants Ao and B are dependent on time, and they decrease with time. The fraction moisture loss/gain (w) is related to time (t) by the equation w = m/t + b0 at all temperatures investigated. The constant m decreases with temperature while b0 increases with temperature. The equilibrium moisture content (the condition reached by the sample when it no longer takes up moisture from or gives up moisture to the surrounding atmosphere) increases with increase in relative pressure and decrease in temperatures. As the moisture content in the fiber increases, the tensile strength (tenacity) decreases and the % elongation increases. The observed results are explained on the basis of structural rearrangement on heating/cooling of lignocellulosic material.
Synthesis and characterization of some new chelating amphoteric ion‐exchange resins
Authors: Kapadia R. N. , Vyas M. V. 
Published: April 2003

AbstractSome new chelating amphoteric ion exchange resins have been synthesized by condensing catechol, 8‐hydroxyquinoline, hydroquinone, salicyclic acid, sulfosalicyclic acid, 3‐hydroxy‐2‐naphthoic acid, p‐hydroxybenzoic acid, β‐resorcylic acid, and anthranilic acid with epichlorohydrin employing diethylenetriamine as a cross linking agent in a nonaqueous medium, toluene. These resins are characterized by their physicochemical properties such as moisture retention ability, true density, apparent density, void fraction, concentration of ionogenic groups, volume capacity, total ion exchange capacity, copper exchange capacity, rate of ion exchange, pH titration curves, apparent pKa and pKb values, isoionic point values, oxidative degradation, thermal stability, the effect of temperature of equilibration on the capacity of the resin, swelling behavior in various solvents, and absorption specificity towards certain bivalent metal cations in ammonium acetate–dimethylformamide media.
The structural interpretation of DSC curve specificity of poly(caprolactam) fibers. I. The specificity of the element of the curve observed in the temperature range ∼40–65°C
Authors: Jeziorny A. 
Published: April 2003

AbstractThe index τ determined from the thermogram was correlated with the selected parameters of the amorphous material structure of polycaprolactam fibers. The investigated structural parameters were as follows: (a) the orientation factor determined by infrared absorption spectroscopy, based on the absorption band at 1130 cm−1; (b) the fraction of taut tie molecules calculated on the basis of the determined axial elastic modulus and volume crystallinity of the fiber. The occurrence of straight‐line relations between the values of the index τ and the values of the investigated structural parameters was found out. The conclusion was formulated that the specificity of the investigated element of the DSC curve reflects the entropy transition rate. That transition, stimulated by fiber heating during the DSC experiment, consists of the increase of the disorder of taut tie molecules. Probably, the rate of that transition changes relatively to the magnitude of the stress affecting taut tie molecules.
Anodic synthesis of sulfur‐bridged polyaniline coatings onto Fe sheets
Authors: Mengoli Giuliano , Musiani Marco M. , Pelli Beatrice , Vecchi Enrico 
Published: April 2003

AbstractSulfur‐bridged polyaniline coatings are obtained onto Fe anodes by electrolyzing a basic solution of one aniline and ammonium sulfide. Their sulfur content ranges from 7% to 17%, depending on the substituents on aniline. Variously substituted anilines may be polymerized in this way and coating pollution by azobenzene formed in a side reaction is almost completely avoided. Sulfur probably enters the polymer chains through a free radical mechanism. HS• intermediates being formed by both homogeneous and anodic oxidation of HS− anions. Coatings from N‐allylaniline, being thermally curable, show satisfactory physical properties.
Effect of copolymerization with methacrylonitrile on the dielectric relaxation of polyacrylonitrile
Authors: Gupta A. K. , Singhal R. P. , Bajaj P. , Agarwal V. K. 
Published: April 2003

AbstractDielectric relaxation in the glass transition region of polyacrylonitrile (PAN), polymethacrylonitrile (PMAN), and their random copolymers containing 6–46 wt % MAN has been studied in the frequency range 102–105 Hz and temperature range 40–160°C. Changes in the dielectric constant increment, relaxation temperature, and the loss peak amplitude with changing MAN content in the copolymers were observed. Dielectric constant increment and loss peak amplitude showed maxima around 6–12 wt % MAN content while the relaxation temperature increased continuously over the entire range. The results are discussed in terms of the possible structural differences arising from the effect of the introduction of MAN units on the dipolar interactions between the nitrile groups.
Hot rolling and quench rolling of ultrahigh molecular weight polyethylene
Authors: Kaito Akira , Nakayama Kazuo , Kanetsuna Hisaaki 
Published: April 2003

AbstractThe mechanical properties, the crystal orientation, and the microstructure of hot rolled and quench rolled ultrahigh molecular weight polyethylene (UHMW‐PE) were investigated. The tensile strength of hot rolled and quench rolled UHMW‐PE sheets increased with increasing draw ratio. The crystallographic axes a, b, and c of the rolled sheets tended to be oriented to the normal direction (ND), the traverse direction (TD), and the rolling direction (RD), respectively. The small‐angle X‐ray scattering patterns with incident X‐ray beam parallel to TD suggested the presence of inclined lamellar structure in the RD–ND plane. At the initial stage of rolling, partial breakup of crystallites along the (100) plane was observed. The lamellar structure is deformed by the slippage mechanism along the (100) plane in the chain direction.
Syntheses of photocrosslinkable polymer from modified poly(methyl vinyl ketone)
Authors: Kinoshita Akihiro , Namariyama Yoichi 
Published: April 2003

AbstractPhotocrosslinkable polymer is prepared from amorphous poly(methyl vinyl ketone) (A‐PMVK) obtained by anionic polymerization of methyl vinyl ketone. The reaction of A‐PMVK with cinnamoyl chloride proceeds in pyridine at 50°C. The photosensitivity of the polymer obtained is measured by infrared and Ultraviolet photometry. The polymer is of a crosslinkable type and forms cyclobutane linkage by ultraviolet irradiation. The polymer is coated on a lithographic aluminum plate and exposed to arc and high‐pressure mercury lamps. Development is with benzene, and standard inking by lithography is applied. The imaging area on the plate is stable and harder than poly(vinyl cinnamate), due to intra‐ and intermolecular cyclization of the main chain. Many good reproductions are produced in the lithographic proofing machine. The photosensitive polymer obtained by A‐PMVK is very useful in relief plates requiring etching.
Determination of the birefringence of an ideal polyester fiber (PET) with regard to the intermolecular interactions
Authors: WŁochowicz Andrzej , Rabiej Stanisław , Janicki Jarosław 
Published: April 2003

AbstractMethod of birefringence determination for an ideal polyester fiber has been described with regard to the interactions of surrounding macromolecules, Δn = 0.2360. Obtained results have been discussed in view of information given in the literature.
Water absorption in acrylic latex films
Authors: Šňupárek J. , Bidman A. , Hanuš J. , Hájková B. 
Published: April 2003

AbstractWater absorption in acrylic latex films was investigated. Films from post‐stabilized latices exhibited low water uptake during a long‐time immersion in water; this was caused by easier extraction of water soluble materials into water. The extraction of secondary emulsifiers was estimated by liquid chromatography; the structure of film surfaces was investigated by electron microscopy.
The study on radiation grafting of acrylic acid onto fluorine‐containing polymers. IV. Properties of membrane obtained by preirradiation grafting onto poly(tetrafluoroethylene–hexafluoropropylene)
Authors: Hegazy El‐Sayed A. , Ishigaki Isao , Rabie Abdelgawad , Dessouki Ahmed M. , Okamoto Jiro 
Published: April 2003

AbstractSome properties of the membranes obtained by preirradiation grafting of acrylic acid onto poly(tetrafluoroethylene–hexafluoropropylene) (FEP) film have been investigated. Swelling behavior, dimensional change by grafting, electric conductivity, and mechanical properties of the grafted films were found to depend largely on the degree of grafting and to increase as the grafting proceeds. These properties were also found to be independent of the preparation conditions such as irradiation dose, grafting temperature, film thickness, and monomer concentration lower than 60 wt %. The electric conductivity of the membranes prepared at lower monomer concentration (lower than 60 wt %) is higher than that prepared at 80 wt % acrylic acid concentration. X‐ray microscopy of the grafted film revealed that the grafting proceeds from both surfaces of the film to the direction of center to give finally homogeneous grafting through the whole bulk of film. At lower monomer concentration the homogeneous grafting was achieved at a degree of grafting around 18%, while at 80 wt % acrylic acid it was achieved at a degree of grafting higher than 70%. The homogeneously grafted membranes show good electrochemical and mechanical properties which make them acceptable for practical uses as cation‐exchange membranes.
The influence of particle size and surface coating of calcium carbonate on the rheological properties of its suspensions in molten polystyrene
Authors: Suetsugu Yoshiyuki , White James L. 
Published: April 2003

AbstractThe rheological properties of polystyrene melts filled with 30 vol % of CaCO3 particles of varying particle size are described. The influence of surface coating the particles with stearic acid is considered. Generally, the compounds with the uncoated particles exhibit viscosities which increase at ever greater rates as the shear rates decrease. It appears that these compounds exhibit yield values. Elongational flow data also suggest the existence of yield values. Difficulties exist in measurement of normal stresses in compounds with sizeable yield values. The principal normal stress difference at fixed shear stress of the PS/CaCO3 compounds is lower than that of the PS melt. The magnitude of viscosity increases and yield values increase with decreasing particle size. Coating of particles with stearic acid results in major viscosity reductions and decreases in apparent yield values. The surface coating is most effective with the smallest particles. It presumably reduces interaction between particles and the extent of aggregation.
Tensile properties of fiberglass‐reinforced polyester foams
Authors: Masi P. , Nicolais L. , Mazzola M. , Snial  , Narkis M. 
Published: April 2003

AbstractHigh‐density structural foams and their fiberglass‐reinforced versions have been characterized in tension, and the results were analyzed. The tensile modulus and strength of the nonreinforced foams can be described by the modified Kerner equation and a modified Nicolais–Narkis equation, respectively. The modulus of the reinforced foams can be predicted by using the concepts of the quasi‐isotropic laminate theory. The temperature sensitivity of the reinforced foams is markedly reduced and the impact failure in a falling ball test is localized, and energy absorption is accomplished by the formation of numerous small cracks. Fiber reinforcement of foams improves also the heat sag resistance and reduces the coefficient of thermal expansion.
Glass transitions of poly(bisphenol‐A carbonate)/ultraviolet light stabilizer blends by DSC and TOA
Authors: Shultz A. R. , Young A. L. , Alessi S. , Stewart M. 
Published: April 2003

AbstractGlass transition temperatures are reported for poly(bisphenol‐A‐carbonate) plasticized by 0–12 wt % of the ultraviolet light stabilizers 2‐hydroxy‐4‐methoxy‐benzophenone, 2‐hydroxy‐4‐n‐octooxy‐benzophenone, and 2‐hydroxy‐4‐dodecyloxy‐benzophenone. Differential scanning calorimetry (DSC) and thermooptical analysis (TOA) were employed. The glass transition temperatures increased somewhat with shelf time for the room temperature air‐dried 1‐mil films drawn from methylene chloride solutions. A Bierbaum scratch hardness of 8.8 kg·mm−2 was observed for a 10‐mil poly(bisphenol‐A carbonate) film. The effect of load applied to the diamond point (Bierbaum scratch technique) on the shape of TOA transmitted light intensity vs. temperature curves for the resultant scratches was examined. Although the curve shapes are greatly affected, the characteristic TOA temperatures derived therefrom remain essentially unchanged. The glass transition regions are not quite as broad for these polymer/plasticizer blends as they are for compatible polymer/polymer blends. TTOA, the temperature at which birefringence disappears in the scratched films, is found identical to Tf (DSC), the temperature at which the specific heat transition is completed.