bluuebunny/crossref_metadata_2025 huggingface dataset:
Alumina–carbon composite fibers from poly[(acyloxy)aloxane]s
Authors: Yamane Hideki , Hashimoto Koichi , Kimura Yoshiharu , Kitao Toshio
Published: April 2003

The alumina–carbon composite fibers were obtained from poly[(acyloxy)aloxane] (PAA) with 3‐ethoxypropanoic (EPA) and m‐anisic acids (m‐AA) legands. This preceramic polymer can be dissolved in p‐xylene‐methanol‐EPA mixed solvent, and the concentrated solution exhibited an excellent spinnability. During the pyrolysis and sintering processes, aliphatic carboxylate in the side groups was easily decomposed and eliminated. The aromatic carboxylate, however, seems to be converted and migrated to a carbon domain in the alumina matrix into which aloxane repetition was converted. The fibers pyrolyzed up to 800 and 1000°C have electrical conductivities that monotonically increase with increasing temperature. The fiber pyrolyzed up to 1200°C showed the electrical conductivity in a rather complicated manner.
Morphology and properties of polyurethane/poly(methyl methacrylate) interpenetrating polymer networks by Co60–γ ray
Authors: Wang Geng‐Chao , Cui Hai‐Wei , Fang Bin , Zhang Zhi‐Ping
Published: April 2003

PU/PMMA IPNs were first synthesized using Co60–γ radiation. The morphology, glass transition behavior, and mechanical properties of the formed IPNs have been studied by TEM, DSC, and electron tensile testing machine. The TEM micrographs and the results of DSC showed that Co60–γ radiation was effective for obtaining small volume sizes of phase domains in IPNs. The structure with two continuous phases occurs in the content range of 40% to 70% PU. The ability of interpenetration enhanced with increasing the content of the crosslinking agents. The mechanical properties of IPNs reflected very good synergistic behavior.
Copolymers of N‐vinylcarbazole with monomers containing carboxylic acid groups or carboxylic anhydride groups. I
Authors: Wainwright M. , Griffiths J. , Guthrie J. T. , Gates A. P. , Murray D. E.
Published: April 2003

N‐Vinylcarbazole has been copolymerized with olefinic monomers possessing carboxylic acid or carboxylic anhydride functionality to yield copolymers with associated solubility in aqueous alkaline media. The copolymers were prepared to be part of a photoconductive lithographic printing plate assembly. The composition of the copolymers and the reactivity ratios have been evaluated. Copolymerization mechanisms are discussed. Alkali solubility has been measured in terms of the decoating speeds of films of the copolymers from aluminum plates. The major aim of producing an alkali‐soluble copolymer that retained the photoconductive properties associated with poly(N‐vinylcarbazole) was achieved in part.
Effect of iron oxides on the thermal degradation of natural rubber from Manihot glaziovii
Authors: Barros Glaucione Gomes De , Ricardo NáGila Maria Pontes , Vieira Vicente Walmick
Published: April 2003

The effect of iron oxides particles mixed in natural rubber (NR) or aged natural rubber (ANR) from Manihot glaziovii were investigated. IR spectroscopy showed that α‐Fe2O3 inhibits or retards the thermal degradation (200°C) of ANR, but it does not inhibit or retard the thermal degradation of NR. A retardation effect is observed using iron (III) oxide in both ANR and NR. Using both oxides, longer autoxidation induction periods of ANR and NR are observed (150°C). The periods were extended for a higher content of rubber hydroperoxide concentration. The inhibition or retardation of autoxidation using Fe3O4 in both ANR and NR is not evident. We suggest an interaction between hydroxyl groups of hydroperoxide, mainly present in aged natural rubber, and the iron oxide surface.
Synthesis and study of some newer polyamides for semipermeable membrane
Authors: Shukla J. S. , Dixit S. K.
Published: April 2003

A series of novel polyamides was prepared by low temperature solution polycondensation of N‐(p/m‐aminobenzoyl aminoacetyl)‐N'‐(4/3‐aminobenzoyl) hydrazine with different diacid chlorides in dry N,N‐Dimethylacetamide (DMAC). The properties of the polyamides for membrane processing were studied with the help of infrared spectra, inherent viscosity, differential thermal, and thermogravimetric analysis. The inherent viscosities were measured in concentrated sulfuric acid at 25±5°C and were in the range of 0.35–0.89 dL/g. The thermogravimetric data in air indicate that the initial decomposition temperature was in the range of 175–200°C. The polymer melt temperature (Tm) and glass transition temperature (Tg) were in the range of 230–450°C and 153.3–300°C, respectively.
Charge transfer copolymerization and properties of isopropyl methacrylate with acrylonitrile and methacrylonitrile
Authors: Bixamaiah B. , Rao P. Raghunath , Sundaram E. V.
Published: April 2003

Isopropyl methacrylate (IPMA) with Acrylonitrile (AN) and Methacrylonitrile (MAN) copolymers of different copositions were prepared at 60°C and 80°C, respectively, using a mixture of n‐Butylamine (nBA) and carbon tetrachloride (CCl4) in dimethyl sulphoxide (DMSO) as a charge transfer (CT) initiator. The percentage composition of the copolymers was established by elemental analysis. The copolymerization reactivity ratios were computed by the Kelen–Tudos method. In both the systems, IPMA was found to be more reactive; the copolymers sequence was random in nature. The copolymers were characterized by IR, 1H‐NMR, 13C‐NMR spectroscopy and intrinsic viscosity measurements in dimethyl formamide (DMF) at 30±0.1°C. The thermal behavior of the AN‐IPMA copolymers was studied by thermogravimetry (TG) in air. The thermal stability increased, with increasing AN content in the copolymer chain. The solubility parameter of AN‐IPMA copolymer was evaluated by studying the intrinsic viscosity in different solvents. The solubility parameter of the copolymer was found to be 9.7 (cal/cc)1/2.
Bead‐spring macromolecules: The kinetic contribution to the total stress
Authors: Grisafi S.
Published: April 2003

Using complete phase space distributions, this analysis predicts an isotropic kinetic contribution to the total stress for both the solvent and polymer. The solvent's contribution depends on the polymer's intramolecular potential energy, as well as the intermolecular potential between the solvent and polymer. The analysis questions whether single molecule distributions are capable of investigating the possibility of anisotropic kinetic distributions. The analysis uses the peculiar velocity fields in lieu of modeling molecular collisions.
Study on organosilicon positive resist. I. Syntheses and characterization of silsesquioxane, siloxane, and silmethylene polymers with phenolic hydroxy groups
Authors: Sugiyama Hisashi , Inoue Takashi , Nate Kazuo
Published: April 2003

Silsesquioxane, siloxane, and silmethylene polymers with phenolic hydroxy groups were prepared in order to obtain alkali‐soluble organosilicon polymers. These polymers have structures in which the phenol moieties are separated by one carbon from the silicon. The hydroxy groups were protected as methoxy groups in polymerization processes, then were changed into hydroxy groups by a reaction with trimethylsilyl iodide followed by alcoholysis. In the course of discussion on the characteristics of these polymers, silsesquioxane with phenolic hydroxy groups is found to possess excellent properties for matrix resins of alkalidevelopable organosilicon resists, such as O2RIE resistance and heat resistance.
Melt‐polymerized aliphatic‐aromatic copolyamides. I. Melting points of nylon 66 copolymerized with aromatic diamines and terephthalic acid
Authors: Kudo K. , Suguie T. , Hirami M.
Published: April 2003

Measurements of melting points were made for melt‐polymerized aliphatic‐aromatic copolyamides; (i) N66PT, (ii) N66CT, and (iii) N66ST, i.e., nylon 66 [poly(hexamethylene adpamide)] copolymerized with three kinds of aromatic diamines, p‐phenylenediamine (P), bis (p‐aminophenyl) methane (C), and bis (p‐aminophenyl) sulfone (S), and terephthalic acid (T). As the mole fraction of copolymerized component n1, increases in the case of (ii) or (iii), the melting point decreases uniformly according to the relationship of Flory. In the case of (i), the melting point first decreases and then begins to increase after passing a minimum at n1 ≃ 0.2. A preliminary WAXD (wide‐angle X‐ray diffraction) study on N66PT crystals shows that the basal plane of the crystal lattice shifts from that of nylon 66 toward hexagonal packing with the increase of n1. It was suggested that the formation of mixed crystals for a series of N66PT will be attributed to their melting point behavior.
Effects of types of fillers on the molecular relaxation characteristics, dynamic mechanical, and physical properties of rubber vulcanizates
Authors: Dutta Naba K. , Tripathy D. K.
Published: April 2003

The dynamic mechanical, and physical properties of bromobutyl rubber were investigated to determine the effect of particle size and of the structure of carbon black and silica. Filler loading was so adjusted that all the experimental compositions had the same hardness level. The results indicate that the type and loading of filler have no significant effect on the molecular relaxation transition. However, elastomer having a desirable storage modulus with low sensitivity to temperature change can be developed using filler with smaller particle size. Higher elongation at break, and better tensile strength, energy density at break, and fatigue life could be obtained by using finer particle or high structure black than with the low structure and higher particle size black. Finer particle size filler loaded systems exhibit pronounced strain dependence, higher thixotropic change, and delayed recovery in dynamic mechanical properties compared to that exhibited by large particle size filler.
Polymer concrete and polymer mortar using resins based on recycled poly(ethylene terephthalate)
Authors: Rebeiz K. S. , Fowler D. W. , Paul D. R.
Published: April 2003

Fundamental properties of polymer concrete (PC) and polymer mortar (PM) made from unsaturated polyester resins based on recycled poly(ethylene terephthalate), PET, are described. Mechanical properties investigated include strength, modulus of elasticity, ductility index, Poisson's ratio, coefficient of thermal expansion, shrinkage, and exotherm. Durability properties include chemical resistance, water absorption, sand‐blast resistance, and thermal cycles of thin overlays on portland cement concrete slabs. Resins based on recycled PET offer the possibility of a lower source cost for forming useful PC and PM (PC/PM) based products. The recycling of PET in PC and PM would also help alleviate an environmental problem and save energy.
Grafting of 2‐(dimethlamino) ethyl methacrylate onto gamma irradiated polypropylene fabric
Authors: Gawish S. M. , Kantouch A. , El Naggar A. M. , Mosleh S.
Published: April 2003

Polypropylene fabric was gamma pre‐irradiated at doses of 1,2 and 3 Mrads. The irradiated fabric was grafted with an aqueous solution of 2‐(dimethylamino) ethyl methacrylate. The graft yield was studied as a function of the different variable conditions such as storage time, monomer concentration (10–40%), reaction time, and temperature (50, 70, 100°C). The grafted polypropylene was further quaternized with dimethyl sulphate or monochloroacetic acid. The grafted and quarternized fabrics were dyed with an acid dye. The fixation properties of the dyed samples were determined by DMF extraction. The moisture regain and mechanical properties were also measured.
Reverse osmosis separation of binary organic mixtures using cellulose acetate butyrate and aromatic polyamide membranes
Authors: Fang Yi , Sourirajan S. , Matsuura Takeshi
Published: April 2003

A systematic investigation has been conducted to demonstrate applicability of reverse osmosis (RO) fractionation of organic liquid mixtures by laboratory‐prepared cellulose acetate butyrate (CAB) and aromatic polyamid (PA) membranes. The determination of preferential sorption was also conducted by using liquid chromatography technique. It was found that reverse osmosis was applicable to the fractionation of organic liquid mixtures. It was also found that the component of the binary mixture that is enriched in the membrane permeate can be predicted by considering the preferential sorption and Stokes' radius for each constituent of the feed mixtre.
Dilute solution properties of cationic poly(dimethyl sulfate quaternized dimethylaminoethyl methacrylate)
Authors: Liaw Der‐Jang , Shiau Saa‐Jen , Lee Kueir‐Rarn
Published: April 2003

The dilute solution properties of a cationic polyelectrolyte, poly(dimethyl sulfate quaternized dimethylaminoethyl methacrylate) [poly(DMAEM · C2H6SO4)], are studied by measurements of intrinsic viscosity, degree of binding, and flocculation application. The intrinsic viscosity of this polyelectrolyte is related to the type and concentration of added salt. The intrinsic viscosity behavior for cationic polyelectrolyte resulting from the electrostatic repulsive force of the polymer chain is contrasted with polyampholyte. The polyelectrolyte in the presence of KCl has a lower degree of binding, indicating that the proton ion (H+) is relatively difficult to bind to the CH3SO4− at the polymer end. The polymerization of DMAEM · C2H6SO4 in 0.5M KCl aqueous solution proceeded more easily than that of DMAEM · C2H6SO4 in pure water. The polymerization rate of DMAEM · C2H6SO4 is found to pass through an extreme value as a function of pH. Optimum flocculation, corresponding to the complete removal of turbidity in the supernatant, is achieved. Beyond the optimum flocculation, high polymer dosages redisperse the bentonite suspensions.
Finely porous models and radially averaged friction factors
Authors: Tremblay A. Y.
Published: April 2003

The finely porous (FPM) and modified finely porous (MD‐FPM) models were used to generate sieving curves for the permeation of polyethylene glycol solutions through a nanofiltration membrane. The curves were calculated at five different operating pressures. Both models use Faxen's equation to calculate the friction factor b−1. Faxen's equation represents the friction between a solute molecule translating along the centerline of a cylindrical pore and the pore wall. The resulting sieving curves were quite different from the typical sigmoidal curves found in ultrafiltration. The departure from this typical shape, was considerable at the lower pressures used in nanofiltration and was less pronounced at the higher pressures found in reverse osmosis. Reasonable sieving curves were obtained when Faxen's equation was radially averaged. Differences in PEG separation of 22 to 32% were obtained between the averaged and the centerline approaches. The partition coefficient K was predicted, for sucrose, raffinose, and NaCl. The use of centerline values of the friction factor led to the overestimation of solute rejection by a factor of 1.24 to 3.11. Finally, in both the FPM and MD‐FPM models, centerline correlations of the friction factor, b−1, must be multiplied by (1−λ)2 in order to be consistent with other averaged quantities.
Theoretical and experimental conversion in the curing of unsaturated polyester resins with styrene as a crosslinking agent
Authors: Ramis X. , Salla J. M.
Published: April 2003

The reaction of unsaturated polyester resin is a free radical copolymerization between the styrene monomer and the unsaturated polyester. Depending on the temperature and other processing conditions, some of the reacting molecular species remain, after curing, in the form of residual monomer and soluble polymer that do not contribute to the network structure. By means of DSC and gel permeation chromatography (G.P.C.) techniques, we have investigated the differences between theoretical and experimental reaction heats of unsaturated polyester samples with different styrene/polyester ratios, the residual species formed, and the conversion of reactive groups.
Properties and structure of never‐dried cotton fibers. III. Cotton fibers from bolls in early stages of growth
Authors: Tsuji Waichiro , Nakao Tokie , Hirai Asako , Horii Fumitaka
Published: April 2003

Like other kinds of cotton fibers already studied, American cotton fibers taken from cotton bolls immediately before and after opening show high angles of torsional rotation during ambient humidity changes. Cotton fibers taken from cotton bolls at 19 and 24 days postanthesis show remarkably higher angles of rotation and much lower dry and wet tensile strengths than the fibers taken from cotton bolls immediately before and after opening. The wet tensile strength of cotton fibers at 24 days postanthesis is higher than the dry strength like the fibers taken from bolls immediately before and after opening, but fibers at 19 days postanthesis show almost the same tensile strength in the never‐dried, dried, and rewetted states. CP/MAS 13C NMR spectroscopy reveals that the never‐dried cotton fibers at 19 days or longer postanthesis have high crystallinities. It seems that the degree of crystallinity is somewhat decreased in the dry state and restored by rewetting. The crystallinity increases with the age of growth.
Facile method for the preparation of tri‐O‐(alkyl)cellulose
Authors: Kondo Tetsuo , Gray Derek G.
Published: April 2003

A simple way to prepare tri‐O‐(alkyl)cellulose from cellulose acetate (CA) in dimethylsulfoxide (DMSO) using the appropriate alkyl iodide and NaOH has been developed. In this procedure, the addition of a small amount of water to the DMSO solution improved the efficiency of etherification. The substitution pattern of (methyl)cellulose (MC) was investigated to determine the effect of added water on the relative reactivities of the glucose ring substituents. This etherification method can be applied to alkylate other polymers with acetate‐functional groups that are soluble in DMSO.
Facile measurement of phenolic end‐groups in bisphenol‐a polycarbonate using GPC‐UV analysis
Authors: Mork C. O. , Priddy D. B.
Published: April 2003

To maximize polycarbonate (PC) stability, it is extremely important that the polycarbonate manufacturing process be operated in such a way as to minimize uncapped polymer chain‐ends. Insurance of complete end‐capping during manufacture would require constant process monitoring using a fast and accurate phenolic end‐group analysis technique for samples typically having > 5% uncapped chain‐ends. Published end‐group analysis techniques are inaccurate if the polymer samples are contaminated with monomer or other small phenolic molecules. Accuracy can be improved by purifying the polymer before analysis, but this procedure is sometimes tedious. This article describes the development of a facile gel permeation chromatography‐ultraviolet (GPC–UV) technique for quantitative determination of low levels of phenolic uncapped chain‐ends in PC. This technique improves accuracy because monomers and other small molecule impurities are separated and excluded from the PC during the analysis.
Role of surfactant in composite latex particle morphology
Authors: Chen Y. C. , Dimonie Victoria , El‐Aasser Mohamed S.
Published: April 2003

Composite particles were prepared by seeded emulsion polymerization at 70°C using K2S2O8 as initiator and two different nonionic surfactants. Monodisperse polystyrene latex particles were used as seed and methyl methacrylate was used as second‐stage monomer. When the surfactant, polyethylene oxide–propylene oxide (Pluronic F‐108), was used, the final particle morphology showed that the PMMA (core) was partially covered by polystyrene. However, when nonyphenol polyethylene oxide (Igepal Co‐990) was used as surfactant, one observed a reversed type of encapsulation (i.e., PS core is partially engulfed by PMMA). The interfacial tensions of the polymer phase against water containing the appropriate surfactant were measured by the drop‐volume method and used in a mathematical model based on thermodynamic analysis to predict the equilibrium particle morphology. The observed particle morphologies were found to differ from the predicted morphologies at low conversion of the second‐stage monomer but agreed with it at higher conversion.
Synthesis and characterization of phenolic and amino resins based on α, β‐unsaturated aldehydes
Authors: Žigon Majda , Šebenik Anton , Osredkar UČi
Published: April 2003

Phenolic and amino resins on the basis of α,β‐unsaturated aldehydes were synthesized in bulk or solution. Catalysts were HCl, H3PO4, or formic acid, and in some cases NaOH. The course of the reactions was followed by GPC and NMR while the structure of the reaction products was determined by one‐ and two‐dimensional NMR. The course of the reactions is influenced by experimental conditions: the type of monomers, their molar ratio, the type and quantity of the catalyst, the reaction time and temperature, and the reaction medium. At the beginning of the reaction the addition of a nucleophile to an aldehyde takes place through parallel 1,2‐addition to and 1,4‐addition to group. Oligomers with OH, , and CHO functional groups are able to add new monomer units or to react mutually to form higher molecular weight addition and condensation products. The overall rate constants for the beginning of the reactions were between 10−3 L/mol s for the high reactive mixtures and 10−7 L/mol s for the less reactive mixtures. The resins were cured by heating at temperatures above 135°C with the addition of hexamethylenetetramine.
Citric acid–diethylenetriamine salts as latent curing agents for epoxy resins
Authors: Galego N. , Vazquez A. , Riccardi C. C. , Williams R. J. J.
Published: April 2003

Citric acid (CA)–diethylenetriamine (DETA) salts (CADETA) were prepared by using a 4.5 : 1 molar ratio of DETA–CA and removing the DETA excess. The structure of CADETA was analyzed by 13C‐NMR, IR, and DSC associated with weight loss. One‐step formulations consisted on dispersions of CADETA (variable amounts) in an epoxy resin based on diglycidylether of bisphenol A (DGEBA, EEW = 185.5 g/eq). The cure was followed in the pressure cell of a DSC (N2 at 2.5 MPa), to avoid volatilization of DETA in the temperature range where decomposition of CADETA and beginning of reaction took place (T > 175°C). A very small heat of reaction was observed, (−ΔH) ∼ 10 kJ/eq, resulting from the simultaneous endothermic salt decomposition and exothermic network formation. A stoichiometric formulation showed a Tg = 180°C, i.e., some 60°C higher than the one observed for the usual DGEBA/DETA system.
Polymer swelling, 13: Correlation of flory–huggins interaction parameter, χ, with molecular structure in polystyrene–liquid systems
Authors: Errede L. A.
Published: April 2003

It is shown that the Flory–Huggins interaction parameters (χ), for polystyrene–liquid systems, reported by others, vary linearly with the readily and precisely determinable relative swelling power (C) of the selfsame liquid, determined in this laboratory using poly(styrene‐co‐divinylbenzene) as the sorbent polymer. This simple gravimetric method appears to be the most suitable for the determination of χ values of polystyrene–liquid systems over the full range of polymer volume fractions. Accordingly, the C values already determined by this method were used to calculate numerous χ values for polystyrene–liquid systems not yet reported in the literature. The data obtained thereby show that χ reflects sensitively the molecular structure of the liquid.
A new equation for estimating [η] from single‐viscosity measurement in dilute solution
Authors: Raju K. V. S. N. , Yaseen M.
Published: April 2003

The use of a linear two‐parameter approximation for determining limiting viscosity number, [η], of a polymer in the state of infinite dilution requires considerable amount of time, effort, and materials. Several workers who attempted to estimate [η] directly from single‐viscosity measurement also proposed equations for this purpose. Such equations are tested and found to have good applicability to practical data within specified limits of concentration or specific viscosity. A new equation has been derived and tested for polymers of high and low molecular weights in various solvents and at different temperatures. The introduction of a constant in this equation makes it applicable over a wider range of specific viscosity. It is found to serve better for determination of [η] from a single‐viscosity measurement.
Low dose γ‐irradiation of some fluoropolymers: Effect of polymer chemical structure
Authors: Rosenberg Y. , Siegmann A. , Narkis M. , Shkolnik S.
Published: April 2003

The effect of low dose (1–20 Mrad) γ‐irradiation on five fluoropolymers (PVF, PVDF, ETFE, FEP, PFA), differing in fluorine content and chain structure, was studied. The radiation effect, reflected by changes in thermal and mechanical properties, as well as NaOH etched surface morphology, was investigated. The main chain structure was found to predominate the irradiated polymers' behavior. The tensile strength of PVF and its resistance to etching increased with radiation dose, while its degree of crystallinity and melting temperature decreased. These changes were correlated with network formation by irradiation and by the incorporation of crosslinked segments into the crystalline phase during recrystallization. Solvent extraction of PVDF (no solvents were found for the other fluoropolymers) revealed increased gel formation with increasing dose. The degree of crystallinity and the tensile strength dependence on radiation dose for PVDF and ETFE reflected the competition between crosslinking and chain scission events. FEP and PFA undergo predominantly chain scission accompanied by reduction of their mechanical properties. PFA even exhibited an increase in both its melting temperature and degree of crystallinity, stemming from a massive degradation process forming shorter chains. Chemical mechanisms are discussed in an attempt to correlate the irradiation effects with the polymers' chain structure.
Catalytic grafting: A new technique for polymer/fiber composites. II. Plasma treated UHMPE fibers/polyethylene composites
Authors: Wang Qi , Ait‐Kadi Abdellatif , Kaliaguine Serge
Published: April 2003

In this paper, the catalytic grafting technique for preparation of polymer/fiber composites is extended to plasma treated ultra‐high modulus polyethylene (UHMPE) fiber/high density polyethylene (HDPE) system. The OH groups introduced on the UHMPE fiber surface by oxygen plasma treatment were used to chemically anchor Ziegler‐Natta catalyst which then was followed by ethylene polymerization on the fiber surface. The morphology and interfacial behavior, as well as the mechanical properties, of the HDPE composites reinforced by catalytic grafted or ungrafted UHMPE fibers were investigated by SEM, DSC, polarized light optical microscopy, and tensile testing. The experimental results show that the polyethylene grafted on the fibers acted as a transition layer between the reinforcing UHMPE fibers and a commercial HDPE matrix. The interfacial adhesion was also significantly improved. Compared with the composite reinforced by ungrafted UHMPE fibers, the composite reinforced by catalytic grafted UHMPE fibers exhibits much better mechanical properties.
Dynamic mechanical analysis of sulfonated polyurethane ionomers
Authors: Ding Jianfu , Xue Gi , Yang Changzheng , Chen Ronshi
Published: April 2003

Dynamic mechanical analysis, using a flat‐spring to support the sample, was conducted to study the properties of polyurethane ionomers prepared from poly(epoxy chloropropane) as polyol. The effects of the soft segment length and ionization level on the properties were studied. For the unionized polyurethane, the soft and hard segments had good compatibility and little phase separation was found due to the high polarity of the polyol. For the shorter hard segment ionomers, as the ionization level increased, the matrix Tg rose due to the increase in the compatibility of hard and soft segments. For the longer ionized hard segment ionomers, the aggregating tendency of ion pairs enhanced phase separation. Quenching or annealing the samples showed that clusters existing in bulk materials did not dissociate below the degradation temperature and multiplets can dissociate or transform to clusters below 150°C.
Phase behavior and mechanical properties of injection molded poly(ethylene terephthalate)/polyarylate blends
Authors: Martínez J. M. , Eguiazábal J. I. , Nazábal J.
Published: April 2003

Directly injection molded blends, composed of poly(ethylene terephthalate) and a polyarylate of bisphenol A, and isophthalic/terephthalic acids have been studied. Both their phase behavior and their mechanical properties after this blending method have been determined. After injection molding, the poly(ethylene terephthalate)/polyarylate blends show a single glass transition by differential scanning calorimetry, although the transition peaks of the blends widen when observed by dynamic mechanical analysis. The calorimetric results show a hindered crystallization of poly(ethylene terephthalate), due to the presence of polyarylate and the occurrence of interchange reactions. The mechanical behavior observed shows an improvement in the small‐strain properties of the blends with respect to those of the pure components. The break and impact properties of the blends show negative deviations with respect to linearity. These deviations are less important when high polyarylate content exists in the blends.
The thermo–oxidative degradation of acrylonitrile–butadiene–styrene copolymers during processing as studied by chemiluminescence
Authors: Memetea Tatiana , Vuluga Zina , Hagiopol Cornel
Published: April 2003

The glow curve obtained upon processing acrylonitrile–butadiene–styrene copolymers (ABS), through various machines, reaches a peak at 180°C. The proper assignment of that peak has required the study of the chemiluminescence (CL) shown by related polymers such as: polybutadiene (PB), styrene–acrylonitrile copolymer (SAN), and polyacrylonitrile (PAN). Three hydroperoxide types associated with the structural units, that is, 1, 2, and cis‐ and trans‐1,4, exhibiting CL peaks at 180, 240, and 340°C, respectively, have been identified in the PB sample. The activation energy (Ea), recorded for the hydroperoxides thermal decomposition, was 15.0 ± 1.0, 17.85 ± 0.9, 20.7 ± 0.8 kcal/mol. PAN shows a CL peak at 180°C. Its occurance is related to the color developed during the thermal treatment. That PAN peak has been attributed to the hydroperoxides generated on the acrylonitrile units neighboring the azomethinic structures. The corresponding Ea is 23.3 ± 1.0 kcal/mol. The same peak (having an identical position and Ea) has been identified with processed ABS and SAN copolymers. As is evident by CL studies, the processing induced oxidation mainly occurs within the SAN phase of the ABS copolymers, though it was also noted within 1,2 units of the PB phase.
Stabilization of vulcanized polyethylene
Authors: Losev Yu. P. , Paushkin Ya. M.
Published: April 2003

Some polyaminedisulphides were studied as thermal stabilizers of polyethylene vulcanized by dicumyl peroxide. The effects of temperature, time, and concentration were investigated. A reaction mechanism is suggested.
Intrinsic viscosity and molecular weight measurement of nylon 66 polymers
Authors: Samanta S. R.
Published: April 2003

Intrinsic viscosity of several nylon 66 polymers in the molecular weight range 25,000–105,000 was measured in hexafluoroisopropanol (HFIP). The experimentally measured viscosity was compared with the data obtained by least‐squares fit of the classical equations of Huggins and Kraemer. The utility of the single‐point viscosity measurement is also discussed and compared with the measured data. The apparent hydrodynamic parameters obtained from the Huggins equation indicate the applicability of HFIP for studying polyamide polymers. The molecular weight of these polymers was also determined by the gel permeation and low‐angle laser light scattering technique (GPC–LALLS). The molecular weight data combined with the viscosity data provide the Mark–Houwink parameters. The agreement between these parameters and the same parameters obtained in tetrafluoropropanol (TFP) is excellent.
Thermal stability of in situ filled siloxane elastomers
Authors: Sohoni G. B. , Mark J. E.
Published: April 2003

Poly(dimethylsiloxane) elastomers that had been filled with in situ precipitated silica were studied by thermogravimetric analysis, under nitrogen and in air. Both types of measurements indicated that the filler raises the temperature of thermooxidative degradation of the polymer, possibly by inactivating the terminal OH groups on the chains. Commercial fume silica was found to cause more severe degradation problems than did the in situ precipitated silica. In all cases, the degradation was more pronounced in air than in the inert atmosphere provided by nitrogen. © 1992 John Wiley & Sons, Inc.
A new technique for preparing monodisperse polymer particles
Authors: Hou Wei‐Hsin , Lloyd Thomas B.
Published: April 2003

A procedure is described for preparing fairly uniform spheres of three different nylon polymers by phase separation. The mean diameter and polydisperse index were 5 μm and 1.056 for Griltex nylon, 5.7 μm and 1.046 for nylon 6/6, and 12.9 μm and 1.016 for nylon 6. The phase separation is done by taking a 1 wt % solution in a theta solvent above the theta temperature and cooling it rapidly. The spheres of the three nylons have various degrees of roughness. Formation of highly uniform particles during phase separation is discussed in a preliminary way. © 1992 John Wiley & Sons, Inc.
Morphology of polymer wear debris resulting from different contact conditions
Authors: Hosseini S. M. , Stolarski T. A.
Published: April 2003

An investigation into the wear process of five polymers tested under different contact conditions is presented. Polymer pin on metal plate and metal pin on polymer plate configurations were used. The metal pin on polymer plate configuration gave significantly lower wear rates compared to that observed for the polymer pin on metal plate configuration. The results are discussed in terms of morphology of wear debris generated.
Structure and physical properties of seed proteins. I. Glass transition and crystallization of zein protein from corn
Authors: Magoshi Jun , Nakamura Shigeo , Murakami Ken‐Ichi
Published: April 2003

Thermal behavior of a seed protein, zein from corn, was studied by differential scanning calorimetry (DSC), thermogravimetry (TG), thermal expansion, X‐ray diffraction, and infrared spectroscopy. Zein film cast from aqueous ethanol is amorphous in the randomcoil conformation. Water in the specimen is lost by evaporation at about 100°C. The glass transition is observed at 165°C. The amorphous zein crystallize to β‐crystals at about 210°C accompanied by the random‐coil → β‐form conformational transition. The thermal degradation of zein occurs at about 320°C. Steam treatment of zein film results in the conformational change to the α‐ and β‐forms, simultaneously, irrespective of treating temperature. © 1992 John Wiley & Sons, Inc.
Thermal aging of plasticized PVC. I. Weight loss kinetics in the PVC—didecylphtalate system
Authors: Audouin L. , Dalle B. , Metzger G. , Verdu J.
Published: April 2003

Weight‐loss kinetics were studied for 10 industrial extruded samples of poly(vinyl chloride) (PVC) plasticized by 20–30% by weight of didecylphtalate at 85, 95, 105, 110, and 120deg;C. For the most unstable samples, which contained a light coplasticizer, the weight‐loss rate obeyed Fick's law. In the other cases, it was constant in the early period of exposure. The apparent Arrhenius parameters (i.e., preexponential factor and activation energy) were intercorrelated and varied strongly from one sample to another. This was explained by the existence of two distinct kinetic regimes corresponding, respectively, to diffusion or evaporation, the whole process being controlled by the slowest step, and a transition between both regimes occurring in the temperature range of exposure. In the proposed model, small changes of the preexponential factor of diffusion from one sample to another are sufficient to take into account the observed behavior.
Poly(vinyl chloride) composition. II. Study of the flammability and smoke‐evolution of unplasticized poly(vinyl chloride) and fire‐retardant additives
Authors: Stoeva S. , Karaivanova M. , Benev D.
Published: April 2003

The influence of natural, activated, and modified microzeolite with the general formula Me2/m · Al2O3 · nSiO2 · pH2O (where Me = Fe3+, Ca2+, Mg2+, Zn2+, K+, Na+) and an organic additive, such as ammonium sulfamate combined with ammonium sulfate on smoke formation and flammability of suspension poly(vinyl chloride) has been studied in the present work. Microzeolite in native (i.e., natural), activated, and modified forms has been found to possess both fire‐retardant and smoke‐suppressant effects in solid poly(vinyl chloride) compositions. Such effects have been best revealed by modified microzeolite containing 3,5–4% zinc. On the other hand, the ammonium sulfamate combined with ammonium sulfate is believed to act as a strong smoke‐suppressant additive. Thermogravimetric examinations and limited oxygen index measurements show that microzeolite acts as a fireresistant and smoke‐suppressant additive predominantly in the condensed phase. The ammonium sulfamate in combination with ammonium sulfate gives evidence of the same effects, mostly in the gaseous phase.
Physical and mechanical behavior of tetraglycidyl diaminodiphenyl methane (TGDDM)/m‐phenylene diamine (m‐PDA) epoxy systems
Authors: Imaz J. J. , Jurado M. J. , Corcuera M. A. , Mondragon I.
Published: April 2003

The rheological behavior of a tetraglycidyl diaminodiphenyl methane with a tetrafunctional aromatic diamine has been studied in terms of the influence of curing agent content and temperature. In this work, critical times corresponding to gelation are used as a measure of activation energy. The dynamic mechanical behavior has been used to analyze the curing extent of these epoxy systems with different amine contents before and after thermal posttreatment. The β‐relaxation peak temperature is found to increase with the curing agent content and also after thermal posttreatment. This has been related to the rise of crosslinking extent. Dependence of flexural mechanical properties on curing agent content and the postcure process has also been determined.
Application of compressed carbon dioxide in the incorporation of additives into polymers
Authors: Berens Alan R. , Huvard Gary S. , Korsmeyer Richard W. , Kunig F. W.
Published: April 2003

It has been found that carbon dioxide remarkably accelerates the absorption of many low molecular weight additives into a number of glassy polymers. This effect is due to the high diffusivity, solubility, and plasticizing action of compressed CO2 in polymers. The transport of CO2 and the effects of CO2 pressure on the transport of other low molecular weight compounds in polymers have been studied by a simple gravimetric method: Polymer film samples were contacted in a pressure vessel with compressed CO2, or with CO2 plus various organic liquids or solids, and the sample weight was followed with a fast‐response electronic balance during subsequent desorption at atmospheric pressure. Upon release of the pressure, absorbed CO2 rapidly diffuses from the polymer, while the other compounds desorb much more slowly. The amount of additive absorbed can be determined from the plateau weight of the sample after most of the CO2 has escaped. Extensive kinetic and equilibrium data are reported for the model system poly(vinyl chloride)/dimethyl phthalate/CO2, and a number of other examples of CO2‐assisted additive absorption are given. This “infusion” process, in effect, amounts to the partitioning of the additive between the CO2‐ and polymer‐rich phases; consequently, the relative solubility of the additive in CO2 and in the polymer is a major factor governing the amount of additive absorbed. Data reported here illustrate the generality and potentially broad applicability of CO2‐assisted polymer impregnation.
Effects of aging on polyimide: A study of bulk and interface chemistry
Authors: Buncick Milan C. , Denton Denice D.
Published: April 2003

We are investigating the bulk and interfacial chemistry of polyimide (PI) exposed to heat and relative humidity (RH) stress (85°C/85% RH) over long periods to understand the long‐term reliability aspects of PI for microelectronic applications. The PI surface chemistry and the PI–Si interface chemistry was followed with electron spectroscopy for chemical analysis (ESCA). For exposure times greater than 550 h, the PI surface exhibits significant changes in emission structure and atomic concentration. The PI–Si interface indicates little change in the PI chemistry when compared to control samples. The water‐contact angle at the PI surface shows no statistically significant change as a function of exposure time. Bulk and surface chemistry were followed with Fourier transform infrared spectroscopy (FTIR) in a grazing incidence reflection configuration. There were measurable differences in FTIR spectra between aged and control samples only for the case of very thin PI layers. These results suggest that for exposure times of less than 1100 h, chemical changes in PI occur primarily at the PI–air interface for samples 1 μm thick and greater. These changes represent a possible rearrangement of the imide structure and may be a form of deimidization of the polymer, but the final state is not polyamic acid. The PI surface chemistry changes observed with ESCA are reversible upon reheating to the cure temperature.
Pervaporation membranes for ethanol–water mixture prepared by plasma polymerization. III. Perfluorocarbon membranes
Authors: Masuoka Toshio , Iwatsubo Takashi , Mizoguchi Kensaku
Published: April 2003

Pervaporation membranes for the ethanol–water mixture were prepared by plasma polymerization of tetrafluoroethylene, perfluoropropane, and perfluoropropylene onto porous substrates. The influence of the monomers on the elemental ratio (F/C) of the polymer depositions by X‐ray photoelectron spectroscopy was rather small compared with that of the W/FM parameter (W = wattage for plasma excitation, FM = mass flow rate of a monomer). The optical emission spectroscopy indicated the similarity of gaseous species formed in the plasmas. The membranes were found ethanol‐permselective, showing separation coefficients (αEtOH) around 4–7 and a wide range of permeation rates (J), 10–10−2 kg/m2 h, for the 4.8 wt % ethanol solution at 40°C. The αEtOH of the membranes with thicker depositions could be correlated to the F/C ratios as a measure of membrane hydrophobicity. It was thought that, by making a plot αEtOH against J values for the perfluorocarbon membranes, they could be classified into three groups on thickness of deposition. The ethanol‐separation mechanisms for each group, which may contain four kinds of mass transfer schemes, i.e., distillation through larger pores, flow of sorption layer at the liquid–membrane interface, and diffusions through deposition or substrate, were also discussed.
Fractionation and characterization of linear low‐density polyethylene at a lower critical solution temperature (LCST)
Authors: Barbalata Alla , Bohossian Takouhi , Delmas Genevìve
Published: April 2003

The composition and molecular weight distribution of linear low‐density polyethylenes (LLDPE) have been determined by fractionation and characterization at a lower critical solution temperature (LCST). The fractionation in 2,4‐dimethyl pentane takes advantage of the fact that the LCST is sensitive to the side‐group content as indicated by the 70 K difference between the LCSTs of PE and polypropylene at the same molecular weight (MW). Temperature‐rising elution fractionation (TREF) and LCST fractions are compared by IR and SEC and also by a new method based on turbidity at an LCST. It is found that the LCST fractionation is sensitive to MW and TREF largely depends on a comonomer content. Calibration of the LCST method for MW distribution and effect of the nature of the comonomer on the LCST are discussed. The LCST technique associated with IR analysis is found to be quite effective for characterizing LLDPE.
Flame‐retarding modification of nylon 6 textile
Authors: Yao Kang De , Han Weiping , Han Dechang
Published: April 2003

For the purpose of flame retardation, nylon 6 textile was first hydroxymethylated and then the methylol group containing nylon 6 textile was finished with Pyrovatex CP at 160–170°C. The limiting oxygen index (LOI) value increased from 23.6 for the original textile to 31.4 for the modified one. The mechanism of flame retardation was investigated using thermogravimetry (TGA), differential scanning calorimetry (DSC), elemental analysis, infrared spectroscopy, and X‐ray diffraction. Results reveal that Pyrovatex CP plays a flame‐retarding role in both the condensed and gas phases.
Synthesis and separation characteristics of strongly basic anion‐exchange resins prepared from different monomers
Authors: Etoh T. , Miyazaki M. , Harada K. , Nakayama M. , Sugii A.
Published: April 2003

Chloromethylstyrene–ethylene glycol dimethacrylate (EGDMA) copolymer beads (PCMS) and dimethylaminomethylstyrene‐EGDMA copolymer (PDAMS) were synthesized by suspension polymerization as noble polymer matrices. The chemical and physical properties of the quaternized resins (PCMS‐Q and PDAMS‐Q) were approximately equal. The characteristics of both resins were examined by high‐performance liquid chromatography using columns packed with the resins. These resins served as conventional anion‐exchange resins for small organic anions, but indicated markedly different retention for large molecular anions, namely, PDAMS‐Q retained proteins having a negative net charge, but PCMS‐Q did not. It was suggested that the chemical and physical structures on the external surfaces of ion exchangers are very important in ion‐exchange chromatography of proteins.
Peel adhesion apparatus using the compound pendulum and its practical performance
Authors: Obori Hiroyoshi , Takenaga Mitsuru , Kasai Akinari
Published: April 2003

An apparatus for measuring the peel adhesion behavior is developed on the basis of the circular motion of the compound pendulum. The peel force versus peel rate characteristics at the increasing and decreasing rates of peeling can be measured in a half cycle of rotation of the pendulum. A personal computer plays the important roles of operating the automated apparatus and processing data in real time. To test practical performance of the apparatus, the relation between peel force and rate of peeling was investigated for various pressuresensitive adhesive (PSA) tapes over a wide peel rate range. The respective curves in peel force versus peel rate in the increasing and decreasing rate processes are consistent with each other in the rate regions where cohesive or interfacial failures occur; while in the transition region between their failures, it appears that a peel hysteresis exists. Furthermore, the conventional testing under constant rate was repeated, and good agreement with the results from the present apparatus was obtained.
Interactions at the PA‐6/PA‐66 interface
Authors: Rybnikár̆ Frantis̆ek , Geil P. H.
Published: April 2003

Refrigerant tubing used in some mobile air conditioning systems has a nylon core, often consisting of nylon 6, nylon 66, or a copolymer thereof. A blend of the homopolymers would be more economical than the copolymer. This article deals with the structural stability of such blends during processing. The crystallization and melting behavior of laminates and solution cast blends of nylon 6 and 66 were examined. Although they do not cocrystallize readily, their at least partial miscibility in the melt and possible coincorporation as crystal defects cause reductions of the melting points and heats of crystallization and fusion of both polymers. The crystallization temperature of the nylon 6, however, increases with increasing nylon 66 content, up to ca. 60% nylon 66, a feature attributed to nucleation of the 6 by the 66. © 1992 John Wiley & Sons, Inc.