bluuebunny/crossref_metadata_2025 huggingface dataset:
Pultruded fiber reinforced blocked polyurethane (PU) composites. I. Processability and mechanical properties
Authors: Chen Chin‐Hsing , Ma Chen‐Chi M.
Published: April 2003

This paper presents a proprietary process developed to manufacture polyurethane (PU) pultruded composites. The blocked isocyanate (NCO)‐terminated PU prepolymer synthesized in this study was prepared from ε‐caprolactam blocked blends of toluene diisocyanate (TDI) and branched polyester. The processability and mechanical properties of various fibers (glass, carbon, and Kevlar 49 aramid fiber) reinforced PU composites have been studied. From the investigation of the pot life of resins, the reactivity of resins, and fiber wet‐out, it was found that the blocked PU prepolymers with chain extender showed excellent processability for pultrusion. Results show that the mechanical properties (i.e., tensile strength, specific tensile strength, flexural strength, specific flexural strength, flexural modulus, and impact strength) increase with fiber content. Kevlar fiber/PU composites possess the highest impact strength and specific tensile strength, whereas carbon fiber/PU composites show the highest tensile strength, flexural strength, specific flexural strength, and flexural modulus. Experimental results of tensile strength of all composites except carbon fiber/PU composites follow the rule of mixtures. The deviation of property of carbon fiber/PU composite is due to fiber breakage during processing. Pultruded fiber reinforced PU composites showed excellent tensile and impact strength compared to other pultruded composites studied.
Pultruded fiber reinforced blocked polyurethane (PU) composites. II. Processing variables and dynamic mechanical properties
Authors: Chen Chin‐Hsing , Ma Chen‐Chi M.
Published: April 2003

Unidirectional fiber reinforced blocked polyurethane (PU) composites have been prepared by the pultrusion process. The effects of processing variables on the mechanical properties and dynamic mechanical properties of fiber reinforced PU composites by pultrusion have been studied. The processing variables investigated included pulling rate (in‐line speed), die temperature, postcure time and temperature, and filler type and content. The dynamic mechanical properties of the composites produced by the process were studied utilizing dynamic mechanical spectrometer. Results show that the composites possessed various optimum pulling rates at different die temperatures. From the DSC data analysis, swelling ratio, and mechanical properties, the optimum die temperature was determined. It was found that the mechanical properties increase with filler content for various types of filler. The increasing of mechanical properties depends on the optimum postcure temperature and time. However, the properties decreased for longer postcure times since the composite materials were degraded. The glass‐transition temperature (Tg) increased slightly and the damping peak (tan δ) was broadened due to fiber reinforcement. The dynamic mechanical moduli (G′, G″) of pultruded PU composites are apparently higher than those of the matrices. The moduli (G′, G″) increase with increasing fiber and filler content, and the damping peak becomes broad. Effect of postcuring on the degree of crosslinking, Tg, and dynamic modulus will be discussed.
Synthesis, characterization, and curing of unsaturated polyamides derived from 2,6‐di(4‐carboxystyryl)pyridine and 2,6‐bis(4‐carboxybenzylidene) cyclohexanone
Authors: Mikroyannidis John A.
Published: April 2003

Two new series of heat‐curable polyamides were prepared utilizing the unsaturated dicarboxylic acids 2,6‐di(4‐carboxystyryl)pyridine (DCSP) and 2,6‐bis(4‐carboxybenzylidene)cyclohexanone (BCBC) as starting materials. They were prepared from the condensation of 4‐carboxybenzaldehyde with a half molar amount of 2,6‐dimethylpyridine or cyclohexanone, respectively. The dicarboxylic acids reacted with various aromatic diamines, utilizing triphenyl phosphite and pyridine as condensing agents, to yield polyamides. In addition, two model diamides were prepared by condensing the dicarboxylic acids with aniline. Characterization of starting materials, polyamides, and model compounds was accomplished by IR and 1H–NMR spectroscopy. The curing behavior of polyamides was investigated by DTA. Upon heat‐curing, the unsaturated polyamides were crosslinked through their olefinic bonds to afford insoluble, heat‐resistant resins. The thermal stability of the resins was evaluated by TGA and isothermal gravimetric analysis (IGA). The cured resins were stable up to 310–322°C in N2 or air and afforded anaerobic char yield of 57–69% at 800°C.
Hydrophilic and adhesive properties of polyethylene plates grafted with hydrophilic monomers
Authors: Yamada Kazunori , Tsutaya Hideyo , Tatekawa Shigeaki , Hirata Mitsuo
Published: April 2003

The photograftings of methacrylic acid (MAA), acrylic acid (AA), methacrylamide (MAAm), and acrylamide (AAm) as hydrophilic monomers onto polyethylene (PE) plates were carried out in the liquid phase. The contact‐angle measurement and the surface analysis by ESCA reveal that the grafted amount at which the PE surface was fully covered with grafted chains increased in the order of MAA > AA > MAAm and was almost the same as that at which contact angles became constant. The grafting of AAm was not sufficient to modify the surface properties of PE. But AAm required the smallest grafted amount to obtain the same adhesive strength as that of the other monomers. The α‐methyl and/or carboxyl groups were required to obtain a high grafted amount. The cos θ value of water on AA‐g‐PE surfaces reached a maximum around 0.02 mmol/cm2 and then decreased. It was confirmed to be caused by cohesion of grafted poly(acrylic acid) (PAA) chains due to the hydrogen bond. For all the monomers used, the adhesive strength increased with the grafted amount. As the concentration of the MAA monomer increased on grafting, at a higher grafted amount, the grafted layer absorbed water more rapidly and the PE plates themselves broke. For AA‐ and MAAm‐g‐PE plates, the amount of absorbed water increased linearly with the grafted amount irrespective of monomer concentration.
Polyvinylpyridine–ethanol systems
Authors: Akin H. , Hasirci N.
Published: April 2003

Polymeric matrices of poly(2‐vinylpyridine) were prepared with application of gamma irradiation to its ethanolic solutions. The interaction parameter (χ) between the polymer and the solvent, and the average molecular weight between the crosslinks (Mc) were calculated from the swelling properties. © 1992 John Wiley & Sons, Inc.
DSC analysis of electron‐beam irradiated LARC–CPI
Authors: Mcherron Dale C. , Wilkes Garth L.
Published: April 2003

This work illustrates the response of LARC–CPI (a crystallizable polyimide) to electron‐beam radiation exposure under a nitrogen‐purged atmosphere. The response of LARC–CPI was monitored exclusively by differential scanning calorimetry (DSC), although some limited X‐ray scattering experiments were also employed. Three different types of LARC–CPI samples were irradiated: the “as‐received” semicrystalline films, highly amorphous films that were quenched from the melt, and recrystallized films. Comparison of the DSC behavior of these specimens elucidated the effects of electron‐beam irradiation on LARC–CPI as well as the influence of morphology (i.e., semicrystalline vs. amorphous states) on the radiation response of this polyimide. Results indicate that for the former two samples electron‐beam radiation does not significantly alter the crystalline phase present during irradiation. However, upon subsequent heating and cooling, the level of crystallinity decreases in all samples exposed to high doses (in excess of 100 Mrad). In addition, the crystallization temperature increases substantially with increasing radiation dosage, while a slight increase in the glass transition temperature is also observed. These results suggest that cross‐linking reactions may be occurring at sufficiently high doses, which would account for the observed melting and recrystallization behavior. However, due to the effects of thermal history on the crystallization behavior, there is some difficulty in definitively discerning all the specific effects of morphology on the radiation response of LARC–CPI.
Methods for predicting the quality of nylon 612 filament for use as a bristle material
Authors: Rawls H. Ralph , Casella Robert , Backus Verne , Dill Robert
Published: April 2003

Splaying and curling of bristles is a very important performance characteristic of nylon toothbrushes. For this reason, analytical methods are needed that correlate fundamental physical–chemical properties with the eventural development of bristle splaying. Differential scanning calorimetry, thermogravimetric analysis, and wide‐angle X‐ray diffraction were each found to identify subtle differences in nylon 612 filament that had been subjected to varying processing conditions during manufacture. These differences were found to be related to water absorption and crystalline perfection and could be correlated with the characteristics of toothbrush wear. From the results, it was concluded that these three methods can be used for quality control and research purposes to predict and to study end‐use performance factors such as bristle splaying. © 1992 John Wiley & Sons, Inc.
High‐viscosity index lubricating oils from EPR destruction products
Authors: Seyidov N. M. , Kuliyev R. S. , Abasov A. I. , Gasanova R. Z.
Published: April 2003

Polyolefinic oils obtained from olefin oligomerization or copolymerization involve the most common synthetic hydrocarbon oils. Research and experimental results concerning high viscosity index synthetic polyolefinic oils and viscosity index improvers' production by ethylene–propylene copolymer (EPR) and thermal destruction of EPRs noted for various molecular weight and composition resulted in high viscosity index polyolefinic oils and thickeners. The effect of structure, composition, and molecular weight on the destruction process has been discussed for various EPRs. The resulting polyolefinic oils and viscosity index improvers were studied. © 1992 John Wiley & Sons, Inc.
The effect of pressure and contaminants on slow crack growth in a butt fusion in a polyethylene gas pipe
Authors: Lu X. , Qian R. , Brown N. , Buczala G.
Published: April 2003

The effect of welding pressure and surface contaminants on butt fusion in a commercial polyethylene gas pipe was studied by measuring the slow crack growth resistance of the joint. Two weld pressures, 1.61 and 0.31 MPa, were used. The contaminants Vaseline, graphite, and Teflon were coated on the surface. It was found that the high pressure produced a weld with much better slow crack growth resistance than that by low pressure. At high weld pressure, Vaseline and graphite showed a negligible effect on weld quality. Teflon greatly reduced the lifetime, especially at low weld pressure. Test results showed that sufficient pressure was necessary to squeeze out the thin skin layer that occurs at the weld interface, along with any contaminants. The butt fusion joints were always much weaker than the reference pipe. This result was attributed to the difference in both cooling rate and molecular orientation between the pipe and weld. © 1992 John Wiley & Sons, Inc.
Efficient, “one‐pot” synthesis of suspension crosslinked sulfonated polystyrene via a Friedel–Crafts reaction
Authors: Theodoropoulos A. G. , Bouranis D. L. , Valkanas G. N.
Published: April 2003

A suspension technique leading to macronet ionic resins is described based on a single reactor process. The procedures demonstrate sulfuric acid as a polar suspending medium that can act as a sulfonating agent, a Friedel–Crafts catalyst, and a crosslinking agent. The sulfonation reaction was finally completed using sulfuric acid excess, or oleum 65%. High yields were obtained for the crosslinking and the sulfonation reaction, while the final products were characterized by using ion‐exchange capacity measurements, U.V. spectra, and determination of the degree of crosslinking. The number average molecular weight between crosslinks and the ion‐exchange capacity H+→Na+ of the resins was decreasing by increasing the nominal crosslinking ratio. © 1992 John Wiley & Sons, Inc.
Metastable solutions and interactions of decomposition products in porogen derived membranes
Authors: Eyal A. M. , Edelstein D. , Hazan B. , Hajdu K.
Published: April 2003

Small incompatible molecules formed on porogen decomposition were found to be metastably dissolved in Porogen Derived Membranes, confirming previous analysis. 1Degrees of metastable dissolution are determined by polymer and porogen characteristics, by porogen content, and by decomposition parameters (characteristics of reagent, its concentration, and decomposition temperature). These parameters determine the characteristics of decomposition products (DPs) formed, the rate of their formation, and the properties of the matrix through which they have to diffuse for phase separation. Extraction experiments indicated that, for many compositions, leaching out of DPs during contact with water is very slow. Porogen derived membranes are thus intermediate between polymeric membranes and supported liquid membranes, with the potential of combining high selectivity and reasonable stability. © John Wiley & Sons, Inc.
Polymeric dye receptors for disperse dyeable polypropylene fibers
Authors: Dayioglu H.
Published: April 2003

Polypropylene fibers containing various amounts and different types of 2‐vinyl pyridine/styrene (2VP/St) copolymer in terms of molecular weight and molar ratio were prepared, and the disperse dyeability of these fibers were investigated. In addition, the disperse dyeability of 2VP/St copolymer alone was also studied. © 1992 John Wiley & Sons, Inc.
Curing of unsaturated polyester resins—effects of comonomer composition. I. Low‐temperature reactions
Authors: Huang Yan‐Jyi , Chen Chaur‐Jeng
Published: April 2003

The effects of comonomer composition on the curing kinetics of unsaturated polyester (UP) resins at 40°C were studied by differential scanning calorimetry (DSC) and infrared spectroscopy (IR) over the entire conversion range. Two commercial UP resins, including UP2821 and UP536B, which on the average contained 6.82 and 4.16 unsaturated CC bonds per polyester molecule, respectively, by 1H‐NMR analysis, were used. Experimental results showed that for UP536B reactions initiated by BPO (benzoyl peroxide)/DMA (N,N‐dimethyl aniline) amine accelerated system, at higher molar ratio of styrene to polyester CC bonds, the DSC rate profile at 40°C exhibited a shoulder after the peak, which could be caused by the grafting reaction of styrene on CC bonds of the polyester chain inside the microgel particles. In contrast, for UP2821 resin, no shoulder was observed presumably because UP2821 reaction systems would lead to a higher crosslinking density during the cure, and styrene molecule could not readily diffuse into the microgel structure at the later stage of the reaction for the reaction shoulder to appear. A microgel‐based reaction mechanism was thus proposed due to the experimental results. © 1992 John Wiley & Sons, Inc.
Energetic ABA and (AB)n thermoplastic elastomers
Authors: Xu Baopei , Lin Y. G. , Chien James C. W.
Published: April 2003

Linear ABA triblock and (AB)n segmented block copolymers of energetic monomers have been synthesized. The rigid and soft blocks are prepared from 3,3‐bis(azidomethyl)oxetane (BAMO) and 3‐nitratomethyl‐3‐methyloxetane (NMMO), respectively. Polymerization of BAMO initiated by triethyloxonium tetrafluoroborate and by spiro(benzoxasilole)/propanediol produced α,ω‐monohydroxy‐PBAMO (3) and α,ω‐dihydroxy‐PBAMO (4) of M̄n 16,000 and 2,000, respectively, and α,ω‐dihydroxy‐PNMMO (5) of M̄n = 13,000 was synthesized by the latter method. The block copolymers were prepared from the appropriate telechelic polymers and toluene diisocyanate. The PBAMO—PNMMO—PBAMO copolymer 6 has Tm = 82°C, Tg = −3°C, and is strongly phase separated even in the melt. It decomposes sharply within 1°C at 224°C evolving 0.69 kJ/g of heat. Copolymer 6 has excellent mechanical properties with elongation of 683% at break, 5.25 MPa stress, and 82% recovery. The (PBAMO—PNMMO)n copolymer 7 has similar thermal properties and spectroscopic characteristic, but is inferior to copolymer 6 in all rheological and mechanical properties. © 1992 John Wiley & Sons, Inc.
Synthesis and evaluation of methyl methacrylate copolymers and terpolymers as electron beam resists. II. Methyl methacrylate copolymers and terpolymers containing aromatic rings
Authors: Gitsov Ivan , Todorova Olga G.
Published: April 2003

Terpolymers of methyl methacrylate and methacrylic acid with vinyl monomers, styrene, 4‐(α, α‐dimethylbenzyl) phenyl methacrylate and 2‐naphthyl methacrylate, were synthesized by radical terpolymerization. The molecular weights of the polymers obtained cover the range of 40,000 to 120,000. It was established that the molecular weight characteristics of the terpolymers are influenced by the content of methacrylic acid in the initial polymerization mixtures, by the chemical nature of the aromatic vinyl comonomer, and by the nature of the solvent and the concentration of the initiator. The sensitivity of the polymers towards radiation was estimated by the G‐values obtained after the products were subjected to γ‐ray treatment. The influence of the chemical composition of the terpolymers on their sensitivity is discussed in detail. © John Wiley & Sons, Inc.
Studies on the preparation and properties of conductive polymers. V. Analysis of metallized polyamide complex metal chelate films and precipitates in metal chelate solution
Authors: Yen Chih‐Chao , Huang Chueh‐Jung , Chang Teh‐Chou
Published: April 2003

Metallized films were obtained by the reduction of polyamide metal chelate films with reducing agents. In the preparation of polyamide metal chelate solution, a small amount of precipitate forms when a certain stoichiometric ratio of formic acid, polyamide, and metal salts was mixed. The precipitate formation rate was affected by kinds and concentrations of metal salts, kinds and molecular weight of polyamide, and solution temperature. In addition, the precipitate formation rate affects the conducting surface metallic substance of reduced nylon/CuCl2/NiCl2 complex metal chelate film. The conducting surface is metallic Ni for low‐molecular‐weight nylon 4/CuCl2/NiCl2 film and metallic Cu for high‐molecular‐weight nylon 4/CuCl2/NiCl2 film reduced by NaBH4 aqueous solution. The precipitate consists of polyamide, metal salt, and formic acid. The interaction among the polyamide, metal salt, and formic acid appears to be by means of hydrogen bonds and ionic bonds. The proposed structure of precipitate was also studied. © 1992 John Wiley & Sons, Inc.
Carboxymethyl starch: A rheological study
Authors: Lapasin Romano , Pricl Sabrina , Tracanelli Paolo
Published: April 2003

The rheological behavior of carboxymethyl starch aqueous systems has been studied under continuous and oscillatory shear conditions. The systems examined exhibited shear‐dependent properties, typical of dispersions having a weak degree of particle aggregation. A transition in the rheological properties was observed with increasing concentration and/or decreasing temperature, as a consequence of formation of a three‐dimensional continuous network in the disperse phase under rest conditions. The shear‐dependent behavior changed from shear‐thinning to plastic and a finite plateau appeared in the low frequency region of mechanical spectra. A rheological model was proposed for the correlation of both shear‐thinning and plastic data, thus making possible an objective definition of the rheological transition. Oscillatory flow data confirmed the results obtained in continuous shear conditions, that is, the frequency dependence of the complex viscosity was almost parallel to the dependence of the steady shear viscosity on the rate of shear. Moreover, the high strain sensitivity of the viscoelastic quantities and their analysis in terms of relaxation spectra clearly indicated the moderate degree of connectivity of the structural network. © 1992 John Wiley & Sons, Inc.
Development of AAS resin by the emulsion–suspension polymerization method
Authors: Kohkame Hisashi , Shitara Masashi , Tanno Seikichi , Muroi Tadashi
Published: April 2003

In order to improve the weatherability of acryonitrile—styrene—butadiene rubber graft polymer (ABS resin), an attempt was made to develop a resin (AAS resin) in which acrylic rubber of good weatherability was used instead of butadiene rubber. First, by copolymerizing dicyclopentenyl‐methacrylate (DCP‐MA,3%) with butyl acrylate, crosslinked acrylic rubber was obtained. This also introduced grafting sites into the rubber. Next, methods of graft copolymerizing styrene and acrylonitrile with this rubber were examined. An emulsion–suspension polymerization method was developed in which the initial stage of the polymerization, emulsion polymerization, changed into suspension polymerization during the process. By this method of polymerization, rubber particles were combined and enlarged, bringing about a graft‐type resin with high impact resistance. This polymerization method is industrially useful because particle‐shaped resins are obtained without the need of a salting‐out process. The AAS resin, obtained in this way, has much improved weatherability over ABS resin and shows strength equal to that of ABS resin. © 1992 John Wiley & Sons, Inc.
Pervaporation through membranes made from acyl derivatives of poly(2,6‐dimethyl‐1,4‐phenylene oxide)
Authors: Schauer J. , Bleha M.
Published: April 2003

Several acyl derivatives of poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO) were obtained by Friedel—Crafts acylation, and the products were used to prepare membranes. During the pervaporation of 10% aqueous solutions of ethanol, acetone, 1‐propanol, or dioxan, membranes made from unmodified, benzoylated, or propionylated PPO (glassy polymers, Tg > 200°C) were preferentially permeable to water, and their separation factors were mainly dependent on the molecular weight of the solvent. Membranes made from palmitoylated PPO (nonglassy polymer, Tg = 34.9°C) were preferentially permeable to organic solvents, and their separation factors correlated with the solubility parameters of the solvents under investigation. As regards membranes made from caproylated PPO (Tg = 130.6°C), there was no unambiguous relation to molecular weights of the solvents or to their solubility parameters. © 1992 John Wiley & Sons, Inc.
Numerical examination of the dual‐mode model for permeation, sorption, and desorption rate curves
Authors: Toi Keio , Saito Koichi , Suganuma Yasushi , Ito Tomoyasu , Ikemoto Isao
Published: April 2003

Numerical solutions were applied to the dual‐mode sorption and transport model for gas permeation, sorption, and desorption rate curves allowing for mobility of the Langmuir component. Satisfactory agreement is obtained between integral diffusion coefficient from sorption and desorption rate curves and apparent diffusion coefficient from permeation rate curves (time lag method). These rate curves were also compared to the curves predicted by Fickian‐type diffusion equations. © 1992 John Wiley & Sons, Inc.
Hydrogen‐peroxide‐initiated polymerization of isoprene in alcohol solutions
Authors: Grishchenko Vladimir K. , Boiko Vitaly P. , Svistova Elena I. , Yatsimirskaya Tatiana S. , Valuev Valery I. , Dmitrieva Tamara S.
Published: April 2003

The radical polymerization of isoprene in alcohol solutions initiated by hydrogen peroxide was studied. It was found that alcohols were components of the initiated system and that their fragments with hydroxyl groups were included in every second molecule of an oligomer irrespective of the type of alcohol, of the monomer conversion, and of the oligomer molecular weight. The oligomer yields and its molecular weight were determined by alcohols through their effect upon the phase state of polymerization systems. © 1992 John Wiley & Sons, Inc.
Crosslinked epoxies: Network structure characterization and physical–mechanical properties
Authors: Vakil U. M. , Martin G. C.
Published: April 2003

A homologous series of epoxy resins, based on the digylcidyl ether of bisphenol‐A, were reacted with stoichiometric quantities of m‐phenylenediamine (mPDA) to form networks with varying crosslink densities. Infrared spectroscopic analyses revealed that the networks were formed predominantly by the epoxy—amine addition reactions with little or no OH‐etherification. The ultimate glass transition temperatures were inversely proportional to the epoxy chain mol wt, as predicted by a model based on the assumptions of additivity and redistributivity of free volume. The average mol wt between crosslinks, M̄c, determined from the dynamic mechanical shear moduli, agreed to within 15 to 18% with the values predicted by the reaction stoichiometry. The glassy‐state modulus did not exhibit any M̄c dependence above room temperature, however, the modulus—temperature plot for all the networks exhibited a discontinuity near −50°C with a steeper slope below −50°C than above it. The change in slope occurred over the same temperature interval as the β‐transition temperature of the networks. The discontinuity in the modulus—temperature plot can be attributed to the freezing of the localized motions of the molecular groups responsible for the β‐transition. © 1992 John Wiley & Sons, Inc.
Effect of the temperature on the drawing behavior of poly(ether ether ketone)
Authors: Russo R.
Published: April 2003

This study examines the drawing behavior of amorphous films of poly(ether ether ketone) (PEEK) and the effect of the drawing and the drawing temperature on some physical properties of the drawn samples. The thermal analysis shows that the amorphous films drawn at 200% of deformation and at temperatures of 80, 120, and 140°C crystallize by heating and the crystallization occurs at lower temperature with a lower crystallization enthalpy. The first effect can be related to the influence of orientation on the crystallization rate and the second to strain‐induced crystallization. The dynamic—mechanical behavior of the drawn samples is in good agreement with the thermal analysis and confirms the presence of strain‐induced crystallization at drawing temperatures well below 180°C. © 1992 John Wiley & Sons, Inc.
Decrystallization of jute by cyanoethylation
Authors: Reddy S. S. , Bhaduri S. K. , Pandey S. N.
Published: April 2003

The cyanoethylation of jute fiber was studied at different reaction conditions. Moisture regain decreased significantly on cyanoethylation. Introduction of 5–6% nitrogen content on the fiber minimized the moisture regain capacity to 2.8%. A further increase in the nitrogen content increased the moisture regain. The effect of cyanoethylation on infrared absorption was studied. The absorbance curves of OH and CH stretching frequencies are parabolic in nature, whereas β‐glycosidic and CH bending absorption curves are almost linear with an increase in the degree of substitution. The cellulosic transition was indicated by the lattice conversion ratio, which showed an increase along with the degree of cyanoethylation. © 1993 John Wiley & Sons, Inc.
Properties of copolymer‐type polyacetal/ethylene–propylene–diene terpolymer blends
Authors: Chiang Wen‐Yen , Huang Chi‐Yuan
Published: April 2003

Two kinds of polymer blends, polyacetals (POMs) and ethylene–propylene–diene terpolymer (EPDM), have been prepared by mechanical blending. The rubbery EPDM was added to the rigid POM matrix to increase toughness. The mechanical, physical, thermal, dynamic mechanical, and morphological properties of these samples have been measured. The notched Izod impact strength and the elongation of the blends reaches a maximum at 7.5 wt % EPDM content. Scanning electron micrographs (SEM) showed that the domain sizes of EPDM vary from 0.25 to 1.0 μm and were independent of the composition. The POM/EPDM blends were determined to be immiscible by SEM, but showed single Tg behavior as determined by differential scanning calorimetry (DSC) and dynamic mechanical analyses up to 7.5 wt % EPDM. Because of that, the Tg's of POM and EPDM were very similar in value. © 1993 John Wiley & Sons, Inc.
Unsaturated polyesters. V. Polyester from maleic anhydride and 1,6‐hexanediol
Authors: Larez V. , Cristobal J. , Mendoza Gilberto A. Perdomo
Published: April 2003

The polycondensation reaction between maleic anhydride and 1,6‐hexanediol, with p‐toluenesulfonic acid as catalyst has been carried out. The product has been analyzed spectroscopically and the molecular weight determined by endgroup analysis and gel permeation chromatography. The influence of spatial interactions between condensed groups on the isomerization of maleate into fumarate is discussed, as well as the effects of even‐ and odd‐ numbered carbon atom glycols. © 1993 John Wiley & Sons, Inc.
Effect of processing conditions on the structural gradients developed in injection‐molded poly(aryl ether ketone) (PAEK) parts. I. Characterization by microbeam X‐ray diffraction technique
Authors: Hsiung C. M. , Cakmak M.
Published: April 2003

Depending on the processing conditions, poly(arylene ether ketone) exhibits unique structural gradients as a result of its thermomechanical history when it is injection‐molded. Gapwise structure gradients change from a fully amorphous to multilayer amorphous–semicrystalline–amorphous and, finally, to a uniformly semicrystalline one when mold temperature is increased. When injection speed is decreased, the crystallized layers become thicker, and at very slow injection speeds, the crystalline layers developed near the two surfaces of the parts approach each other at the core. These structure variations were characterized by differential scanning calorimetry, optical microscopy, and a matrixing microbeam X‐ray diffraction (MMBX) technique developed in our laboratories. The relationship between the structure gradients developed and the processing variables and the cavity geometry are discussed. © 1993 John Wiley & Sons, Inc.
Novel polyetherurethaneurea elastomers based on α,α,α′,α′‐tetramethyl‐m‐xylenediisocyanate: Synthesis, characterization, processability, and hydrolytic stability
Authors: Gunatillake Pathiraja A. , Meijs Gordon F. , Rizzardo Ezio , McCarthy Simon J. , Chatelier Ronald C. , Brandwood Arthur , Schindhelm Klaus
Published: April 2003

A series of novel polyetherurethaneurea elastomers based on m‐TMXDI, polyether macrodiols containing 4, 6, 8, or 10 methylene groups between the ether linkages, and aliphatic and aromatic diamines was prepared by two‐step solution polymerization. All the materials were thermally processable at 120–160°C except one that was solvent‐castable. Mechanical properties and hydrolytic stability (at neutral pH) were found to depend on the macrodiol and chain extender. Poly(tetramethylene oxide)‐based polyetherurethaneureas that were chain‐extended with primary aliphatic diamines, other than 1,3‐propanediamine, exhibited significantly better mechanical properties than those chain‐extended with secondary aliphatic or aromatic diamines. The mechanical properties and hydrolytic stability of polyetherurethaneureas containing poly(hexa‐, octa‐, or decamethylene oxide) and 1,6‐hexamethylenediamine were considerably better than those containing 1,2‐ethylenediamine. The hydrolytic stability increased with the increasing C/O ratio of the macrodiol. With poly(hexamethylene oxide)‐based materials, the phase separation between soft and hard domains was higher than that of the other materials as determined by DSC. © 1993 John Wiley & Sons, Inc.
Stress–relaxation in three‐element and four‐element mechanical models of viscoelastic materials
Authors: Joye Donald D.
Published: April 2003

Three‐ and four‐element mechanical analogues are commonly used to describe viscoelastic behavior in creep (deformation under constant force or stress) but not in stress relaxation (stress response after a suddenly imposed, constant strain). Mathematical models of the mechanical analogues in stress–relaxation are re‐derived in this work, keeping notation familiar to polymer scientists. The relationship is shown to meet consistency tests and predicts, with very good accuracy, the behavior of a polyisobutylene sample in stress relaxation when the equation constants were derived from creep experiments. In experiments on an actual mechanical analog, the motion of the Voigt element is shown to exhibit a maximum stress. Implications for the interpretation of creep and stress–relaxation data on the same material are discussed. © 1993 John Wiley & Sons, Inc.
A comparison of the tetramethylthiuram disulphide accelerated sulfur vulcanization of polybutadiene and polyisoprene
Authors: Cassem A. , McGill W. J.
Published: April 2003

A detailed study of the vulcanization of polybutadiene with various combinations of sulphur, tetramethylthiuram disuphide, ZnO, stearic acid, and zinc dimethyldithiocarbamate is reported. Vulcanization was conducted by heating samples at 2.5°C/min in a differential scanning calorimeter. The reaction was stopped at various points along the vulcanization exotherm, the soluble reaction products and residual curatives were extracted and analyzed, and the crosslink density and percentage polysulphidic crosslinks were determined. The overall reaction mechanism was found to be similar to that for polyisoprene, but the reaction, once initiated, was faster than in polyisoprene, the crosslink density was higher, and the percentage polysulphidic crosslinks was lower. These differences are discussed. © 1993 John Wiley & Sons, Inc.
Ternary phase equilibria of polystyrene with a second polymer and a solvent
Authors: Geveke David J. , Danner Ronald P.
Published: April 2003

Phase diagrams including tie lines for nine ternary solvent–polymer–polymer systems have been obtained using size exclusion chromatography. The systems studied were toluene–polystyrene (PS)–isoprene rubber (IR), toluene–PS–butadiene rubber (BR), cyclohexane–PS–BR, tetrahydrofuran(THF)–PS–poly(methyl methacrylate) (PMMA), and THF–PS–poly(butyl methacrylate) (PBMA) at temperatures between 30 and 75°C. The results indicate PS‐PMMA is less compatible than PS‐PBMA in the presence of THF. Also, the combination of trans‐ and 3,4–IR‐PS is less compatible than cis–IR‐PS in the presence of toluene. The original Flory–Huggins model for ternary systems has been modified to account for the concentration dependence of the interaction parameters. The modified Flory–Huggins model consists of two interaction parameters per binary. Using this model, six parameters have been regressed for each of the experimental systems studied. Although the parameters are not physically meaningful, the model and the parameters obtained using it are useful for correlating the experimental phase diagrams. The results obtained using the modified six parameter model are shown to be superior to those obtained using the original three parameter model. © 1993 John Wiley & Sons, Inc.
Synthesis and mesomorphic behavior of terminally carboxyl oligo(ethylene oxide) monomethyl ethers‐substituted side chain liquid crystalline polysiloxanes. I
Authors: Jeng Gow‐Pyng Cheng , Kuo Jen‐Feng , Chen Chuh‐Yung
Published: April 2003

A series of alkene monomers containing carboxyl biphenyl benzoate ester or carboxyl p,p′‐phenyl benzoate ester based on mesogenic core with a carboxyl (±)‐2‐methyl ethylene glycol monomethyl ether group or various lengths of carboxyl oligo (ethylene oxide) monomethyl ethers as the terminal group were synthesized. And they were grafted onto the poly(methylhydrosiloxanes) (PMHS) by the platinum catalyzed hydrosilylation process. Their molecular structure, the thermal transitions temperature, and mesophase texture of monomers and of polymers were characterized using 1H nuclear magnetic resonance, differential scanning calorimetry, and polarizing optical microscopy with hot stage. The polymers obtained all show smectic phase while their precursor monomers show both smectic and/or nematic phase, or in some cases, no mesophase. The factors governing mesophase texture and transition temperature are discussed. © 1993 John Wiley & Sons, Inc.
Effect of filler on rheologic and thermodynamic characteristics of binary polymeric mixture melts
Authors: Lipatov Yu. S. , Shumsky V. F. , Rosovitsky V. F. , Getmanchuk I. P. , Kvitka N. A.
Published: April 2003

Rheologic, thermodynamic, and mechanical loss tangent properties of a binary polymeric mixture were studied. The system was a mixture of poly(vinyl acetate) (PVA) with ethylenevinyl acetate copolymer (EVC) with varying concentrations of the polymer components and filler. A correlation between the above characteristics of the PVA/EVC two‐phase mixture was found. This mixture was thermodynamically unstable (positive values of the interaction parameter, χ) practically over the entire range of compositions at temperatures of rehologic studies. The presence of a disperse filler raised the thermodynamic stability, that is, parameter χ decreased. Reversal of the sign of the temperature dependence of χ of a mixture with increasing concentration of filler was found. The variations of viscosity with the composition, temperature, and shear for the PVA/EVC mixture are ascribed to different levels of heterogeneity occurring in the process of the shear straining in the working unit of the rheometer. © 1993 John Wiley & Sons, Inc.
Determination of optimum blending conditions for poly(vinyl chloride)/epoxidized natural rubber blends
Authors: Nasir Zainal A. , Ishiaku Umaru S. , Ishak Zainal A. Mohd
Published: April 2003

An attempt to resolve the difficulties normally faced in preparing PVC‐dominant PVC/ENR blends with the Brabender plasticorder is discussed. As expected, it was found that the mechanical properties of PVC/ENR blends are greatly influenced by the mixing parameters, which are further reinforced with evidence from both dynamic mechanical analysis (DMA) and morphological studies. Both techniques showed the attainment of compatible 50/50/PVC/ENR blends, the former a single glass transition temperature (Tg) and the latter a single‐phase system, albeit their inherent properties are dependent on the blending parameters. By utilizing the correlation between mixing temperature and rotor speed derived, good PVC/ENR blends can be easily procured. © 1993 John Wiley & Sons, Inc.
Study of the acid hydrolysis of the starch graft copolymers with hydroxylic methacrylates
Authors: Gurruchaga M. , Goñi I. , Valero M. , Guzman G. M.
Published: April 2003

The acid hydrolysis method is usually utilized to separate acrylic polymer chains grafted onto amylopectin (AMP). The hydrolysis with the HCl acid has been found to be appropriate when we grafted hydroxyethyl methacrylate (HEMA) and hydroxypropyl methacrylate (HPMA). Using the perchloric acid method, various secondary reactions appear falsifying the grafting yields. © 1993 John Wiley & Sons, Inc.
Permeation of several gases through elastomers, with emphasis on the deuterium/hydrogen pair
Authors: Fitch M. W. , Koros W. J. , Nolen R. L. , Carnes J. R.
Published: April 2003

The diffusion and permeation coefficients for He, H2, D2, O2, and N2 in a variety of elastomers were measured by simple manometric methods. The elastomers studied were butyl rubber; Hypalon® 40 and 45; Viton® E60 and GF; Hydrin® 100 and filled Hydrin® 100; Kraton® G, FG, and KG VTEOS; EPDM; epoxidized natural rubber; and neoprene. Consistent with earlier studies, elastomers with higher glass transition temperatures exhibited lower diffusion coefficients. The ratio of diffusion coefficients of the hydrogen isotope pair differed from the purely molecular‐weight‐based prediction. Deuterium's slightly smaller size relative to hydrogen is consistent with observed deviations from the molecular‐weight‐based diffusion coefficient ratio. © 1993 John Wiley & Sons, Inc.
Improvement of wood properties by impregnation with macromonomeric initiators (macroinimers)
Authors: Hazer Baki , Örs Yalçin , Alma M. Hakki
Published: April 2003

Scotch pine, eastern spruce, and eastern beech samples sawed longitudinally were impregnated with a new type of polymerization mixture (macroinimer and styrene), leading to crosslinked block copolymers of styrene and poly(ethylene glycol). Weight gains of 36.37–91.13% were obtained after polymerization for 2 h. Water uptake of the polymerized wood was found to be 35.13–72.07% after a water soak test of 144 h. While spruce gave the highest uptake (72.07%), beech showed the lowest value (35.13%). The specimens impregnated with the mixture of macroinimer and styrene showed a water‐repellent effectiveness of 35.14–58.15% after a water soaking test of 144 h. The highest values of water‐repellent effectiveness were found for spruce, while the lowest values were obtained for pine. A maximum antiswell efficiency (ASE) of 42.43% was obtained for spruce, followed in order by beech and pine, respectively. The ASE value increases with an increase in wt % gain. Improvements of 19.12% in longitudinal compression and 25% in bending strength were also achieved for spruce samples with low weight percent gain. IR spectroscopy was used for chemical characterization of the wood–polymer composite. © 1993 John Wiley & Sons, Inc.
Surface and interfacial FTIR spectroscopic studies of latexes. V. The effects of copolymer composition on surfactant exudation
Authors: Thorstenson Timothy A. , Urban Marek W.
Published: April 2003

The influence of copolymer structure on the magnitude of surfactant enrichment to the film—air and film—substrate interfaces of latex films prepared on a polytetrafluoroethylene (PTFE) substrate is investigated. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR FTIR) is used to elucidate the surfactant enrichment by the comparison of butyl acrylate/methyl methacrylate/methacrylic acid (BA/MMA/MAA) and ethyl acrylate/methacrylic acid (EA/MAA) latex systems prepared with various anionic surfactants. It is found that, in all cases, the magnitude of exudation of the sulfonate‐containing surfactants manifested by the presence of S—O bending and scissors modes is reduced in the case of the BA/MMA/MAA latex. Similar behavior is observed when the spectra of films prepared on a liquid mercury substrate are compared. It is believed that this behavior results from the longer aliphatic n‐butyl groups present in this copolymer that enhances compatibility by providing a greater opportunity for hydrophobic surfactant—copolymer interactions. The butyl groups may also reduce excess interfacial free energy by orienting themselves toward the film interfaces, which, in turn, will reduce the surface tension‐induced driving force for surfactant exudation. © 1993 John Wiley & Sons, Inc.
Miscible and immiscible blends of ABS with PMMA. II. Mechanical and surface properties
Authors: Kim Byung Kyu , Shin Gui Sook , Kim Young Jin , Park Tae Sung
Published: April 2003

Mechanical and surface properties of injection‐molded specimens for miscible and immiscible blends of ABS with PMMA were investigated. Regardless of miscibility, hardness, modulus, and strength of the blends generally showed a smooth variation with composition, with the possible exception of impact strength. In miscible blends, impact strength decreased smoothly with PMMA; however, in immiscible blends, a drastic drop to less than the half that of ABS was obtained at 10 wt % PMMA. Compounding at higher temperature gave decreased modulus and strength and increased impact strength. Surface gloss decreased with PMMA addition in the miscible system and increased in the immiscible system up to 50 wt % PMMA. From contact‐angle and FTIR measurements, it is suggested that the surface properties are governed by miscibility and the viscosity ratio of the components. © 1993 John Wiley & Sons, Inc.
Characterization of the surface layer of integrally skinned polyimide membranes: Relationship with their mechanism of formation
Authors: Perez S. , Merlen E. , Robert E. , Addad J. P. Cohen , Viallat A.
Published: April 2003

A series of dense films and membranes was prepared using different processes; their surface morphology was investigated by transmission electron microscopy using the replication technique. On the basis of TEM results, SEM observations of cross sections of membranes and gas‐separation properties of membranes, two kinds of membrane morphology are evidenced in relation to their preparation conditions and final properties. The first one gives an ultrafiltration‐type membrane. Large nodules are observed on the surface of the membranes. It is suggested that these are formed by liquid–liquid separation that occurs by nucleation and growth of the polymer‐rich phase. The second one yields gas‐separation‐type membranes. No nodules are evident at the surface of these membranes. The skin is formed by a step that concentrates the initial solution. It is followed by the transformation of the solution in the glassy state. Liquid—liquid separation takes place below the first skin layers by nucleation and growth of the polymer‐poor phase. © 1993 John Wiley & Sons, Inc.
Fractionation of low molecular weight polyethylene by high‐pressure soxhlet extraction
Authors: Scholsky Kevin M.
Published: April 2003

The use of quantitative, high‐pressure Soxhlet extraction for the fractionation of low molecular weight polyethylene samples is described. Liquid carbon dioxide was found to be a suitable solvent for the lowest molecular weight hydrocarbons but failed to solubilize hydrocarbons with molecular weights greater than C‐40—C‐50. Liquid pentane was found to be an effective solvent for hydrocarbons that were insoluble in liquid CO2. Careful, stepwise adjustment of the extraction solvent temperature produced polymer fractions with molecular weight distributions substantially narrower than those of the parent materials. Polymer fractions with molecular weights up to C‐90 were analyzed by high‐temperature gas chromatography. These analyses demonstrated the effectiveness of the technique in fractionating polymers according to molecular weight. Further evidence was provided by thermal analysis of the fractions that indicated melting‐point transitions that were much sharper than those of the parent materials. High‐pressure Soxhlet extraction offers considerable potential as a general method for purification and fractionation of synthetic and natural polymers. © 1993 John Wiley & Sons, Inc.
SEC–viscometer detector systems. I. Calibration and determination of mark–houwink constants
Authors: Lew R. , Cheung P. , Balke S. T. , Mourey T. H.
Published: April 2003

Five different types of calibration curve currently used in size exclusion chromatography‐differential viscometer (SEC–DV) systems were identified and their use summarized. A simple method of deriving weighting factors for fitting local intrinsic viscosity calibration curves was shown to greatly improve the precision of calculated molecular weight distributions. The problem of reliably extrapolating the fitted curves to allow for differences in sensitivity among detectors has yet to be examined. With regard to Mark—Houwink constants, a method of fitting data from the SEC–DV system to obtain more statistically sound values was derived. For the data used here, the new method involves fitting a plot of logarithm of the local intrinsic viscosity of the sample vs. logarithm of the universal calibration curve parameter, Ji. Results for the data obtained appeared only slightly more precise than those for the traditional method. However, the new method promises improved reliability. © 1993 John Wiley & Sons, Inc.