bluuebunny/crossref_metadata_2025 huggingface dataset:
Morphological studies of blends containing liquid crystalline polymers with poly(ethylene terephthalate)
Authors: Ko C. U. , Wilkes G. L. , Wong C. P.
Published: April 2003

The investigation involved the structure–property behavior of extruded cast films prepared from blends of thermotropic liquid crystalline copolyesters with poly(ethylene terephthalate) (PET). Data were obtained which showed not only the temperature dependence of the moduli and stress–strain behavior but also the orientation effects that must be prevalent in order to explain the differences between the moduli measured parallel and perpendicular to the extrusion direction. Only at high liquid crystal polymer (LCP) composition is the modulus particularly increased. The modulus enhancement with lower LCP content and utilization of process variables are discussed with respect to the induced morphological textures and nature of the process equipment. Specifically, the process variable extruder gear pump speed did not enhance Young's modulus at the same LCP content as extensively as did the process variable of extruder screw speed.
Thermal behavior and fiber studies of certain azoaromatic polyamides
Authors: Rajendran V. , Nanjan M. J.
Published: April 2003

Two aromatic polyamides containing azo linkage in the main chain were synthesized and characterized by TGA, DTA, and pyrolysis–GC–chemical ionization mass spectra. Fibers were also spun using a laboratory scale wet spinning unit and their mechanical and morphological properties studied. The results were correlated with structure and spinning conditions.
Structure and viscoelastic properties of epoxy resins prepared from four‐nuclei novolacs
Authors: Hasegawa Kiichi , Fukuda Akinori , Tonogai Saburo
Published: April 2003

The relation between the structure and the viscoelastic properties of seven kinds of epoxy resins was studied. Seven tetraglycidylethers were synthesized from four‐nuclei novolacs in which the positions of methylene linkage or number of kind of substituents were different. These epoxy compounds were cured with diaminodiphenylmethane as a hardener. From the viscoelastic properties of the fully cured resins with the hardener, characteristic properties such as glass transition temperature (Tg), average molecular weight between crosslinking points (M̄c), and front factor (ϕ) were obtained. It was concluded that higher linearity in the main chain of epoxy resins gave a cured resin with a higher Tg, a smaller M̄c, and a larger ϕ.
Swelling of porous ethylvinylbenzene–divinylbenzene copolymers and the stability of the pore structure
Authors: Jun Yan , Rongnan Xu , Juntan Yan
Published: April 2003

A series of porous ethylvinylbenzene–divinylbenzene (EVB–DVB) copolymers with DVB contents ranging from 22.0 to 98.4% were prepared using various amounts of toluene as the inert diluent, and studies were made on the copolymers as to their swelling properties, the stability of their pore structure, and the relationship between swelling in nonsolvents and variations in their pore structure. The swelling experiments showed that the ethanol regains of the copolymers were closely related to the course of phase separation, and the increases in both the DVB content and the volume fraction of monomers in the organic phase resulted in enhanced capacity of the highly crosslinked copolymers to keep swelling in solvents having extremely small affinity for these copolymers. The variations in pore structure, sometimes quite considerable, for copolymers pretreated with different solvents were observed even at DVB content up to 98.4% and further studies showed that a consistent relationship existed between pore volume variation and volume swelling ratio in ethanol for toluene modified copolymers.
Copolymerization of styrene with fumaronitrile initiated by L‐ascorbic acid
Authors: Kuramoto Noriyuki , Sakoh Kenji , Nagai Katsutoshi
Published: April 2003

Copolymerization of styrene (ST) with fumaronitrile (FN) initiated by L‐Ascorbic acid (L‐Asc) was investigated in dioxane containing a small amount of methanol in the presence of atmospheric oxygen. L‐Asc was found to initiate the alternating copolymerization of ST with FN at mild conditions. The copolymerization rate Rp was found to increase with increasing L‐Asc concentration and was found to depend on [L‐Asc]0.6 [(ST) + (FN)]2.7. The overall energy of activation as calculated from Arrhenius plot was found to be 10.9 kcal/mol−1 within the temperature range of 25–40°C.
Hydrolysis of cationic polyacrylamides
Authors: Aksberg Rein , Wågberg Lars
Published: April 2003

The alkaline hydrolysis of two acrylamide‐based polyelectrolytes has been investigated. The experiments were carried out in buffered aqueous solutions in the pH range of 3.5–8.5 and in the temperature range of 22–50°C. 13C‐NMR analysis of the hydrolysis product showed that choline chloride was the substance released upon hydrolysis. The decrease in charge density of the copolymer due to the hydrolysis was studied by polyelectrolyte titration and nitrogen analysis. The results show that the rate of hydrolysis increased with increasing pH or increasing temperature. In the hydrolysis of C‐PAM 1 at 22°C and pH 6, the half‐life of the cationic groups was 10 days. At pH 7 the half‐life was shorter, 24 h, and at pH 8.5 the reaction was very fast with a half‐life of about 0.25 h. The charged groups on C‐PAM 2, the polymer with the higher charge density of the two polymers studied, have somewhat longer half lives than those on C‐PAM 1. This can be explained by the structure of the polymers.
Preparation of ion‐exchange celluloses. I. Anion exchange celluloses
Authors: Khalil M. I. , Wally A. , Kantouch A. , Abo‐Shosha M. H.
Published: April 2003

Cellulose–poly(glycidyl methacrylate) graft copolymer (CPGMA) was treated with ammonia (AH), ethylamine (EA), diethylamine (DEA), and triethylamine (TEA). Factors affecting the reaction, such as reaction duration, temperature, liquor ratio, pH, and aminating agent/epoxide molar ratio were studied. A mechanism of the reaction was suggested. The anion exchange celluloses were characterized by studying its capacity, potentiometric titration, and durability to use. Potentiometric titration of the produced anion exchangers has been studied and pKb values were found to be 6.1, 7.6, and 8.9 for DEA–CPGMA, EA–CPGMA, and AH–CPGMA, respectively.
Dynamic mechanical analysis of fibers. I. Effect of experimental variables and material type
Authors: Khanna Y. P. , Wenner W. M. , Kumar R. , Kavesh S.
Published: April 2003

Depending upon the fiber material, some of the experimental variables can have a profound effect on the dynamic tensile modulus vs. temperature data. With the use of an experimental fiber (25°C < Tg < 75°C; Tm > 220°C; hot stretched), the effect of several variables, e.g., moisture/volatiles, annealing/relaxation, frequency (strain rate), pretension, and % strain on the modulus retention term [(E100°C/E25°C) × 100] have been studied. Of these variables, pretension and especially % strain dramatically increase the modulus retention and this effect is attributed to the elastic orientation under force (EOF), i.e., it exists only in the presence of tensile forces and is reversible. Such an effect was insignificant for Kevlar (Tg − 375°C) and absent for steel wire. Dynamic modulus measurements at 25°C using sonic techniques also support the EOF phenomenon in polyethylene yarns (Tg ∼ −30°C) but not in Kevlar polymide yarns (Tg ∼ 375°C).
Structural interpretation of plasma‐polymerized propargyl alcohol
Authors: Yoshimura K. , Kitade T. , Kitamura K. , Hozumi K.
Published: April 2003

Vapor of propargyl alcohol under reduced pressure was glow‐discharged for plasma polymerization by which hydrophilic polymer film could be deposited onto a solid substrate. The hydrophilic property was more enhanced with use of the same monomer containing water. An interpretation of chemical structures of the polymer molecules was therefore attempted to discover the reason of the hydrophilic property. The polymer materials were subjected to IR spectroscopy, 13C‐NMR and 1H‐NMR spectroscopies, elemental analysis, number average molecular weight determination, mass spectrometry, and other wet chemical analysis for . The IR spectra of the polymers showed the presence of OH, CO, and CC groups with a disappearance of CC group of the monomer. It was also found that the molecular formula of a solvent extract of the polymer derived from the plain monomer was C26H36O9 ≒ 490, involving four hydroxyl, one carbonyl, and two to three olefinic unsaturation groups within a unit molecule. On the other hand, the polymer from 60% water‐containing monomer showed its molecular formula as C44H66O18 ≒ 890, containing seven to eight hydroxyl, two carbonyl, and one to two olefinic unsaturation groups. This information was used to establish the symbolic chemical structures of the polymer molecules. It has been found that both polymers were not as much crosslinked as other plasma polymers because of having side chains with fewer branching. The oxygen atoms were retained in the polymer not only as the forms of OH and CO but also as a member of the principal frame of the polymers.
Activation parameters and the catalytic effects of poly(3‐alkyl‐1‐vinylimidazolium) salts on the hydrolysis of neutral phenyl esters
Authors: Papathomas K. I. , Israel S. C. , Salamone J. C.
Published: April 2003

Alkaline hydrolyses of p‐nitrophenyl acetate (PNPA) and p‐nitrophenyl laurate (PNPL) were studied in the presence of poly(3‐methyl‐1‐vinylimidazolium iodide) (PVII‐C1), poly(3‐n‐hexadecyl‐1‐vinylimidazolium iodide) (PVIII‐C16) and their monomeric analogs. The polysoap (PVII‐C16) was a completely quaternized polyion, in contrast to other polysoap systems that have been studied. The hydrolysis of PNPA was not affected by these polyions. The hydrolysis of PNPL was instead enhanced by the addition of these cationic polyions. The magnitudes of the enhancement were in the order of PVII‐C16 > PVII‐C1, which is explained in terms of the hydrophobicity of these polyions. Values of k2, the rate constant of the polymer substrate complex, indicated that the esters bound to the polymer were more reactive than the free esters. Binding or association constants (K) obtained also increased in the order PVII‐C16 > PVII‐C1. Inhibitory results were observed for the hydrolysis of PNPL in presence of 3‐n‐hexadecyl‐1‐vinylimidazolium iodide (VII‐C16). The activation parameters for these reactions were also investigated.
Compatibilization of natural rubber–polyolefin thermoplastic elastomeric blends by phase modification
Authors: Choudhury Namita Roy , Bhowmick Anil K.
Published: April 2003

Natural rubber–polyolefin (70/30) blends have been studied by incorporation of modified rubber and plastic phases with a view to make the heterogeneous phases compatible. The modified rubbers used were epoxidized natural rubber (ENR) and sulfonated ethylene–propylene diene rubber (S‐EPDM) at a level of 20 parts. Other rubbers such as chlorinated polyethylene (CPE) and ethylene propylene diene rubbers (EPDM) were also used at a level of 20 parts in the natural rubber–polyethylene (NR/PE) systems. The plastic phase was chemically modified with maleic anhydride (MA) in presence of benzoyl peroxide (BPO) and used at a concentration of 10% of PE, i.e., PEm. The tensile properties such as the modulus, elongation at break, tensile strength, and hysteresis were studied. NR/ENR/PEm/PE shows the greatest improvement in tensile strength (45% over control NR/PE). NR/S‐EPDM/PEm/PE also shows similar improvement, although the hysteresis loss decreases. The change in these properties could be related to the adhesive strength. This was found to be improved by the incorporation of modified rubber and modified plastic phases. The best adhesion values have been obtained with NR/ENR/PEm/PE and NR/S‐EPDM/PEm/PE. Thus, a correlation between tensile and adhesive strength was obtained for all the systems. The increase in adhesive strength is due to chemical reactions between the various phases. Probable chemical reactions have been suggested. Morphological observations show that the phases are interpenetrating, and this is consistent with the increased tensile strength. The natural rubber–polypropylene (NR/PP) systems do not offer good strength properties with the modified PP and modified rubbers. The adhesive strength also decreases with the incorporation of the modified system. The hysteresis properties show some improvement.
Characterization of physical aging of poly(methyl methacrylate) powders by a novel high pressure sorption technique
Authors: Stewart M. E. , Hopfenberg H. B. , Koros W. J.
Published: April 2003

High pressure CO2 sorption isotherms were measured at 35°C in previously dilated PMMA microspheres, which were subsequently aged in vacuum at 35°C. The dilation was induced by preswelling with high activity methanol vapor at 13°C, or alternatively with CO2 at a pressure of 20 atm and a temperature of 5°C. The state of the samples during long‐term aging was probed by rapid and intermittent determination of complete high pressure CO2 isotherms. The dilation increased the sorption levels observed in the sorption experiments compared to those observed in untreated samples and, as the aging time increased, the sorption level progressively decreased. The isotherms under all conditions were well described by the dual mode sorption model. The observed time dependence of the isotherms was successfully described by confining all changes in sorption capacity to a systematic decay of the Langmuir capacity parameter. The equilibrium parameters of the model, however, were essentially unaffected by the preswelling and aging histories.
Synthesis and some properties of PVC‐bound dimethylglyoxime complexes of Co(II), Ni(II), and Cu(II)
Authors: Biswas Mukul , Moitra Subrata
Published: April 2003

Poly(vinyl chloride) (PVC) has been reacted with dimethylglyoxime (DMG) in THF to form the PVC–DMG comples, which has been characterized by spectroscopic and elemental analyses. The latter indicate that there is one DMG moiety anchored on the PVC chain by displacing every 12th Cl atom in the chain. PVC–DMG has further been reacted with alcoholic solutions of Co(II), Ni(II), and Cu(II) to form the intensely colored PVC–DMG–M(II) complexes. The structures of these complexes have been analyzed by elemental and IR spectral analyses. The overall thermal stability of PVC–DMG–M(II) increases in the order: PVC < PVC–DMG–Cu(II) < PVC–DMG–Ni(II) < PVC–DMG–Co(II). The electrical conductivities are also significantly enhanced in the same order. The permittivities of these complexes are high relative to PVC at low frequency falling gradually with increasing frequency and the dielectric loss‐frequency behavior is very broad.
DSC and13C‐NMR studies of the imidazole‐accelerated reaction between epoxides and phenols
Authors: Hale Arturo , Macosko Christopher W. , Bair Harvey E.
Published: April 2003

The imidazole‐accelerated reaction between epoxides and phenols has been studied through DSC and13C‐NMR of model compounds. The selectivity of the accelerator has been found to be strongly dependent on its concentration. If a low amount of accelerator is used, the reaction takes place almost exclusively through the addition of phenols to epoxides even if the latter are used in excess. However, a larger amount of accelerator will cause the secondary hydroxyls (produced by the main reaction) to react with the epoxides. In any case, the lower reactivity of the secondary hydroxyls prevents them from reacting to any significant extent as long as there are any phenols present. When polyfunctional resins are used, the effect of the selectivity of the reaction on the properties of the crosslinked network is very clear. If a low amount of accelerator is used (to promote only the epoxy–phenol reaction), the maximum glass transition temperature (Tg) occurs when the epoxides and phenols are stoichiometrically balanced, reaching 178°C. However, when an excess of epoxides over phenols is used, along with a larger amount of accelarator, the maximumTgincreases its value to 199°C.
Structure and viscoelastic properties of epoxy resins prepared from o‐cresol novolacs
Authors: Hasegawa Kiichi , Fukuda Akinori , Tonogali Saburo , Uede Kazuo
Published: April 2003

The relation between the structure and viscoelastic properties of the epoxy resins prepared from o‐cresol novolacs was studied. Our model epoxy resins were two kinds of epoxy compounds synthesized from three‐nuclei and four‐nuclei o‐cresol novolacs. In addition to these models, a commercially available o‐cresol novolac‐type epoxy resin was also studied. Each of the three epoxy compounds was cured with one of three kinds of novolacs, which were starting materials of the above‐mentioned epoxy resins. Characteristic properties of the cured resins, such as glass transition temperature (Tg), average molecular weight between crosslinking points (M¯c), and front factor (ϕ) were obtained. It was concluded that the number of functional groups contained in the curing system almost dominated the viscoelastic properties of the cured resins.
Synthesis of copolymers of N,N‐dimethyl acrylamide and methacrylate esters and their surface tensions
Authors: Weinert Raymond J. , Piirma I.
Published: April 2003

A systematic study was made on the preparation of N,N‐dimethylacrylamide (NDMA)/ methacrylic ester statistical copolymers. The methacrylic ester comonomers used in the copolymerizations were ethyl, n‐butyl, n‐hexyl, n‐octyl, n‐dodecyl, n‐hexadecyl, and n‐octadecyl methacrylates. It was found that the NDMA copolymers could be prepared in three molecular weight regions: 1.0 × 104, 2.0 × 105, and greater than 1.0 × 106 ([η] in water at 30°C of 0.1, 0.6, and greater than 1.5 dL/g, respectively). The molecular weights of the copolymers were dependent on the solvent employed in the polymerizations and on the presence of a chain transfer agent (t‐dodecyl mercaptan). All copolymer compositional analyses were made by 400 MHz 1H‐NMR spectroscopy. The NDMA/methacrylic ester copolymers decreased the surface tension of water in the order: C4 = C6 > C8 > C12 > C16 > C2 = C18 > P(NDMA), lowest surface tension (35 dyn/cm) to highest surface tension (59 dyn/cm).
Gradient high‐performance liquid chromatography of statistical and block copolymers of styrene and t‐butyl methacrylate
Authors: Glöckner Gottfried , Müller Axel H. E.
Published: April 2003

Copolymers of styrene (S) and tert‐butyl methacrylate (TBMA) containing 24–92 mass % of the latter monomer were investigated using a silica column with isooctane/tetrahydrofuran (THF) gradients and on a phenyl bonded‐phase column by methanol (MeOH)/THF gradients using UV detection. In both cases, retention decreased with increasing TBMA content of the sample. This is in contrast to the behavior of copolymers of S and methyl methacrylate (MMA) whose retention in gradient elution on silica columns increases with MMA content due to the polarity of this unit. The inversion of elution order is a result of the bulky TBMA residues shielding the polar groups of the ester units. For copolymers of varying composition, the gradation in retention on retention on silica is quite sufficient for separating S/MMA but not for S/TBMA mixtures. The latter could be separated by composition on phenyl packings through MeOH/THF gradient elution. Block copolymers containing 80 or 92% TBMA could be baseline‐separated. It was also possible to separate these samples from admixed PTBMA or PS homopolymers. Under the conditions used, the retention of a given block copolymer was somewhat higher than that of a statistical copolymer having the same composition. A block copolymer containing 80% TBMA was converted by transesterification into a S/MMA block copolymer. The elution of the latter fitted well in the sequence of S/MMA copolymers on silica column.
Electrochemical preparation of electrically conducting polyurethane/polyaniline composite
Authors: Pei Qibing , Bi Xiantong
Published: April 2003

Composite films from polyaniline (PANi) and polyurethane (PU), with flexibility and mechanical strength similar to pure PU and conductivity close to pure PANi, have been obtained by electropolymerizing amiline on a PU/Pt electrode in water/acetonitrile/ethylen glycol electrolyte solution. In the composite films, PANi is dispersed, in the form of particulate, inside and on the inner surface of the PU substrates. It is found that the electropolymerization reaction of aniline proceeds much faster in basic solution and composite film as prepared shows higher conductivity than that in acidic solution. PANi in PU/PANi composite film is protonic‐acid‐doped and is conducting even in case it is electropolymerized in a basic electrolyte solution.
Adhesion of photocurable acrylates to solid polymer substrates
Authors: Jönsson S. , Gölander C. G. , Biverstedt A. , Göthe S. , Stenius P.
Published: April 2003

The adhesion of a hydrophilic (surface tension γ ≈ 40 mj/m2) and a hydrophobic (γ ≈ 30 mj/m2) photopolymerized acrylate lacuer a low‐density polyethylene, polystyrene, polycarbonate, polymide‐6‐6, polyvinylchloride, polyethyleneterephthalate, poly‐(1,1)‐difluoroethylene, and polymethylmetacrylate has been investigated. A primary condition to obtain sufficient adhesion, as probed by the Scotch tape test, is that the surface tension of the lecquer has to be lower than the critical surface tension of the lacquer. There is no obvious correlation with possible doner/acceptor interactions between lacquer and substrate. Even when spreading occurs, other factors may cause insufficient adhesion. On polyamide, residual moisture on the surface is vary detrimental to adhesion. Extending the lag‐time between application and curin reduced adhesion, in particular to polymers containing aromatic groups. This appears to be due to inhibition of the polymerization reaction by radiation‐adsorbing aromatic groups in the swollen interphase. The effect can be avoided by proper choicd of initiator and radiation‐adsorbing aromatic groups in the swollen interphase. The effect can be avoided by proper choice of initiator and radiation source. Curing of the lacquers in a nitrogen atmosphere generally results in poor adhesion because the rate of polymerization/curing becomes very high compared with rats of relaxation of stresses in the lacquer.
Elastomeric polyurethanes reinforced with aramid fibers
Authors: Andreopoulos A. G. , Konstantinidou A. V. , Petsalas H. J.
Published: April 2003

Thermolplastic polyurethane is a relatively new development in the elastomers field, combining elastomeric behavior with thermoplastic processing characteristics. Thus, high production rate and reduced scrap can be achieved but, increased versatility for the incorporation of additives is also possible. In this work, thermoplastic polyurethane matrices were prepared and Kevlar pulp was dispersed as a reinforcing agent. Since good dispersion and appropriate filler volume fraction are critical factors for a reinforcing effect, special attention was paid to the optimization of these parameters. Thermoplastic polyurethanes were prepared by mixing a low melting polyol with a low melting diisocryanate and the subsequent addition of small amounts of a chain extender, namely, a low molecular weight diol such as 1,4 butanediol. The Kevlar pulp was added under stirring either in the polyol or the diisocyanate melt. This incorporation technique allows the disperision of small fiber percentages. Thus, calendering of the materials prepared was also performed and additional fibers were incorporated. Changes in the properties of properties of the specimens prepared as a function of the filler volume fraction and the dispersion technique were determined, taking into consideration the possibilities of chemical interaction between fibers and matrix.
Annealing studies on a fully cured epoxy resin: Effect of thermal prehistory, and time and temperature of physical annealing
Authors: Pang K. P. , Gillham J. K.
Published: April 2003

The dynamic mechanical behavior at about 1 Hz of a fully cured epoxy resin (maximum glass transition temperature, Tg∞, ca. 170°C) ahs been studied during and after isothermal annealing in terms of the influence of thermal prehistory, time of annealing, and temperature of annealing (Ta). Annealing temperatures ranged from Tg − 15 to Tg − 130°C. The rate of isothermal annealing was observed to decrease by a decade for each decade increase of annelaing time when the material was far from equilibrium. Annealing at high temperatures did not measurably affect the mateiral properties during cooling (for T ≪ Ta); similarly the effect of annealing at low temperatures was not measurale during heating (for T ≫ Ta).
Graft copolymer of gelatin/butyl acrylate and its use in the dye transferring blank film
Authors: Li Zhi‐Chong , Fu Zhi‐Feng , Huang Ming‐Zhi , Miao Jin‐Kang , Lian Na
Published: April 2003

Butyl acrylate was graft copolymerized onto gelatin using ceric ammonium nitrate as redox initiator. A series of grafted products with various gelatin‐to‐butyl acrylate ratios were prepared. The molecular weight of the grafted side chains and the number of grafting sites were measured. The possible grafting sites on gelatin macromolecules were pointed out through amino acid analysis. The electron micrograph and DSC analysis showed that the grafted chain (PBA) and backbone gelatin were in separated phases. The graft copolymer was used in the receiving layer of the dye transfer blank film, and the photographic, dye transfer printing, and some physicomechanical properties were studied with satisfactory results.
Polymerization of surface‐active monomers. III. Polymer encapsulation of silica gel particles by aqueous polymerization of quaternary salt of dimethylaminoethyl methacrylate with lauryl bromide
Authors: Nagai Katsutoshi , Ohishi Yoshiyuki , Ishiyama Kadzuo , Kuramoto Noriyuki
Published: April 2003

Polymer encapsulation of silica gel particles (SiO2) by aqueous, radical polymerization of a cationic, surface‐active monomer, quaternary salt of dimethylaminoethyl methacrylate with lauryl bromide, in the presence of the solid was investigated. The polymerization gave the polymer encapsulating the solid particles (“C‐polymer”), though accompanied by the formation of that suspended in form of latex (“L‐polymer”). The proportion of C‐polymer in the products increased with increasing the amount of SiO2 at a constant monomer concentration and only C‐polymer was formed under the conditions where the feed ratio of monomer to SiO2 is about 0.13 or lower by weight. Increasing the monomer concentration in feed increased slightly the ratio of C‐polymer to SiO2. The results obtained here suggest that C‐polymer is mainly formed through the polymerization of monomer adsorbed on the solid surface. An electron micrograph of the polymer‐encapsulated SiO2 revealed that the solid particles are uniformly encapsulated with the resulting polymer.
Effect of E/P ratio on the rheology and morphology of crosslinkable polyethylene and EPDM blends
Authors: Mukhopadhyay P. , Das C. K.
Published: April 2003

Effects of E/P ratio of the EPDM rubber on the flow behavior and morphology of the crosslinkable polyethylene and EPDM blends have been studied as a function of shear rate and processing temperature. High‐E/P‐ratio EPDM rubber exhibits high viscosities within the temperature range studied but the extrudate swell is higher for the low E/P ratio EPDM. Shear modulus, stored elastic energy and flow activation energy are higher for high E/P ratio EPDM but relaxation time is higher for low E/P ratio EPDM. At a particular blend ratio these rheological parameters show a change in their pattern. This point of change in pattern occurs at a lower level of EPDM having a high E/P ratio; this suggests an early phase inversion as corroborated by the SEM studies. Melt fracture occurs to a larger extent for the low E/P ratio EPDM in its blends with XLPE.
Modified phenol–formaldehyde novolac resins: Synthesis and thermal oxidative degradation
Authors: Tuǧtepe M. , Özgümüş S.
Published: April 2003

New phenolic resins containing titanium and silicon in the main polymer structure were synthesized and some of their properties were investigated. Titanium and silicon contents of the polymers ranged from 2 to 13% titanium and from 2 to 5% silicon. These polymers became insoluble and infusible as the titanium and silicon contents of the products were increased. IR spectra of these modified resins were presented. The thermal oxidative degradations of the phenolic resins modified with titanium and silicon were also investigated using thermogravimetry and differential thermal analysis. Titanium and silicon‐modified polymers, showed considerably lower weight changes as compared with those of unmodified or titanium‐modified polymers, but the rate of the last oxidative degradation increased and the final degradation temperature decreased with increasing titanium concentration. The best results for the thermal resistance was found to be 2% ≤ Ti ≤ 6% and Si 2–5%.
Isothiocyanato‐substituted hydrophilic polymer beads for immobilization of enzymes
Authors: Kitano Hiromi , Hasegawa Masanori , Kaku Takashi , Ise Norio
Published: April 2003

Styrene–glycidylmethacrylate–divinylbenzene resin beads could be converted to highly hydrophilic resin beads by acid treatment. These resin beads could be modified with isothiocyanato (NCS) groups quite easily using a Friedel–Crafts reaction and a subsequent nucleophilic reaction with KSCN. The resin beads substituted with NCS groups were useful as supports to immobilize enzymes, because they were not only hydrophilic but also bind proteins covalently. The enzymes immobilized onto the resin beads showed sufficiently high catalytic activities for a long period.
Stretching of PET films under constant load. II. Structural analysis
Authors: Le Bourvellec G. , Beautemps J.
Published: April 2003

The structure development of a PET film is studied during drawings under constant load. The evolution of crystallinity, amorphous orientation, and axial and planar birefringences is described along a deformation path. The influence of the stretching force and stretching temperature is also analysed.
A crack layer approach to fatigue crack propagation in high density polyethylene
Authors: Kasakevich M. L. , Moet A. , Chudnovsky A.
Published: April 2003

Fatigue crack propagation (FCP) in high density polyethylene (HDPE) is observed to occur with an accompanying layer of damage ahead of the crack tip. The crack layer theory, which accounts for the presence of both the damage and the main crack, is applied to the problem. It is observed that the kinetic behavior of HDPE under fatigue consists of three regions: initial acceleration, constant crack speed (“deceleration”), and reacceleration to failure. Within the first two regions, crack propagation appears “brittle,” while in the third region “ductile” behavior is manifested. Ultimate failure occurs via massive yielding of the unbroken ligament. Two damage mechanisms are found to be responsible for HDPE failure: formation of fibrillated voids and yielding. Both mechanisms are present throughout the entire lifetime of the crack, but the former dominates the “brittle” crack propagation region, while the latter is more prominent in the “ductile.” Throughout the analysis the resistance moment Rt is approximated as the total volume of transformed material associated with crack advance. Crack layer analysis produces a satisfactory fit of the experimental data and yields a specific enthalpy of damage, γ*, value in the 1–2 cal/g range.
Studies on binary and ternary blends of polypropylene with ABS and LDPE. II. Impact and tensile properties
Authors: Gupta A. K. , Jain A. K. , Ratnam B. K. , Maiti S. N.
Published: April 2003

Studies on impact and tensile properties of binary blend of PP and ABS and ternary blend of PP, ABS, and LDPE are presented. Variation of impact strength and the fracture surface morphology with blend composition is examined and interpreted. Tensile behavior in the yield region is studied and the trends of variation of work of yield and impact strength are compared to ascertain the predominent mechanism of impact toughening in these binary and ternary blends. An analysis of yield–stress data in terms of theoretical models is presented to reveal the differences in these binary and ternary blends, attributable to the role of LDPE component in the ternary blend.
Characterization of interfacial interactions in high density polyethylene filled with glass spheres using dynamic‐mechanical analysis
Authors: Kubát J. , Rigdahl M. , Welander M.
Published: April 2003

The dynamic‐mechanical properties of high density polyethylene filled with 20% by volume of untreated glass spheres or glass spheres treated with a silane‐based coupling agent were studied as a function of temperature and imposed tensile deformation. The coupling agent used is capable of providing covalent bonding between the polymeric matrix and the glass spheres. It is assumed that an interphase region is formed in the matrix around each filler particle with properties depending on the surface treatment of the filler, but different to that of the bulk matrix. It is shown how the mechanical loss factor can be used to characterize the properties of the interphase region and the degree of adhesion between the two phases, as affected by the surface treatment. We suggest that these kinds of measurements can be valuable when determining the effectiveness of various surface treatments of filler particles from a mechanical point of view.
Characterization of the polymer‐supported phase transfer catalyst
Authors: Chou Su‐Chu , Weng Hung‐Shan
Published: April 2003

Polymer‐supported phase transfer catalysts, which were prepared by immobilizing tributylamine on chloromethylpolystyrene, were characterized by optical microscope, SEM, EPMA, and ESCA. Both optical photograph and electron micrograph showed that the exterior surface of polymer support became wrinkly after immobilization in dry condition. The surface of the triphase catalyst may become smooth after being swelled by solvent. From the ESCA analysis in a depth of about 100 Å, it was found that 46.5% of covalent chloride in chloromethylpolystyrene had reacted with tributylamine and converted to quaternary ammonium chloride. However, the EPMA, which analyzed in a depth of about 1 μm, gave a value of only 31% and the titration method which was for the whole bead gave 14.3%. These results reveal that the catalyst has a higher content of quarternary ammonium chloride in the outer shell. It is concluded that the high activity of this catalyst is due to the fact that it contains both hydrophobic and hydrophilic groups on the exterior surface, and more active species in the outer shell.
Binding of chrysophenine G by methyl cellulose and poly(vinyl alcohol)
Authors: Shibusawa Takao , Tanaka Akira , Yamaguchi Yutaka
Published: April 2003

Equilibrium constants (nK) for the binding of Chrysophenine G by methyl cellulose (MC) and poly(vinyl alcohol) (PVA) were determined spectrophotometrically in the temperature range 15–40°C. The polymer chains of PVA extended by the dye binding but those of MC shrank slightly. The enthalpy change and the entropy change for the binding by MC were negative and positive, respectively, whereas those for the binding by PVA were both negative. When the dye was bound to the extended polymer chains, the contribution of the entropy term to the binding increased. The rate of the dye bindings was studied by means of the temperature jump method. For the dye binding to PVA, the whole relaxation process finished in a very rapid step. On the other hand, for dye binding to MC, the initial rapid step was followed by two successive slower steps; the relaxation times for the slower steps were independent of the polymer concentration. The results were interpreted in terms of the stiffness of polymer chain of MC; the conformational change of the stiff chains to accommodate the dye in stable states seems to be the rate determining step in each slow relaxation.
Fatigue behavior of acrylic interpenetrating polymer networks. II
Authors: Hur T. , Manson J. A. , Hertzberg R. W. , Sperling L. H.
Published: April 2003

Energy‐absorbing simultaneous interpenetrating networks (SINs) based in polyether‐type polyurethanes (PUs) and poly(methyl methacrylate) (PMMA) networks were prepared by a prepolymer procedure. The products are translucent and appear to have single and broad glass transitions, suggesting some degree of phase separation. The percent energy absorption determined from dynamic properties and pendulum impact tests, the resistance to fatigue crack growth and fracture toughness (K1c) all increase with polyurethane content. The fracture behavior changes from brittle to ductile failure with increasing PU. The fatigue fracture surfaces of the SINs show extensive stress whitening associated with cavitation around the polyurethane domains, and localized shear deformation rather than crazing.
Optimum preparation conditions of amidoxime hollow fiber synthesized by radiation‐induced grafting
Authors: Saito Kyoichi , Yamaguchi Takeo , Uezu Kazuya , Furusaki Shintaro , Sugo Takanobu , Okamoto Jiro
Published: April 2003

The preparation process of amidoxime hollow fiber consists of three steps: (1) radiation‐induced graft polymerization of acrylonitrile (AN) onto porous hollow fiber (AN grafting), (2) chemical conversion of the cyano group into an amidoxime group (amidoximation), and (3) conditioning of the hollow fiber with alkaline solution (alkaline treatment). Systematic optimization of this preparation process was found to improve the adsorption rate. For the AN‐grafted hollow fiber having 130% degree of grafting, the optimum reaction was 1 h each for amidoximation and alkaline treatment, respectively. Also the change in the structure of the amidoxime hollow fiber with alkaline treatment was discussed based on measurements of water content, swelling and pore volume distribution, and observation of morphology of cross section by SEM.
Nonlinear dynamics and the problem of polymer fracture
Authors: Manevitch L. I. , Zarkhin L. S. , Enikolopian N. S.
Published: April 2003

The results of the experimental and molecular‐dynamics study of the process of mechanical degradation of polymer chain, testifying to the essential role of nonthermal channels of dissipation of elastic energy accumulated during deformation, have been discussed. High‐energy molecular products of mechanical degradation, which are able to induce a chain branching process leading to “explosive” formation of submicrocrackes, have been discovered. It has been noted that a considerable part of polymer chain energy is concentrated in localized excitations of a soliton type, which play the determining role at all the stages of mechanical degradation under consideration.
1H‐NMR studies on water in methacrylate hydrogels. I
Authors: Yamada‐Nosaka Atsuko , Ishikiriyama Kazuhiko , Todoki Minoru , Tanzawa Hiroshi
Published: April 2003

The behavior of water contained in a hydrophilic hydrogel poly(hydroxyethyl methacrylate) membrane and a hydrophobic hydrogel poly(methyl methacrylate) membrane was studied by proton nuclear magnetic resonance (NMR) spectroscopy. Significant differences between the two hydrogels were observed in their relaxation times, the temperature dependence, and frequency dependence of these relaxation times, and changes of signal intensity of water protons on freezing and thawing. The water in these hydrogels was classified into three states: free, intermediate, and bound states. Poly(hydroxyethyl methacrylate) contains relatively more water in bound and intermediate states than poly(methyl methacrylate). The mobility of water decreases in the order, free water, intermediate water, bound water. The correlation times of the three states were roughly estimated to be 10−11, 10−9, and 10−6 s, respectively. The mobility of water in poly(methyl methacrylate) is several orders of magnitude higher than that in poly(hydroxyethyl methacrylate). In poly(hydroxyethyl methacrylate), the exchange between intermediate and free water is slow in the NMR time scale: the apparent exchange rate and the activation energy were estimated to be 3.6 × 102 s−1 (28°C) and 2.0 kcal/mol, respectively.
Studies on the preparation and properties of conductive polymer. I. Novel method to prepare metalized plastic from metal chelate of poly(vinyl alcohol)
Authors: Yen Chih‐Chao , Chang Teh‐Chou , Kakinoki Hideo
Published: April 2003

A novel and easily processed conductive polymer was prepared from poly(vinyl alcohol)(PVA). Metal chelate onto PVA film exhibited excellent surface resistivity around 100–102 Ω/cm2 when it was treated with reducing agents. The surface of these films was treated with reducing agents which possessed a definite metallic luster. The conducting surface proved to be metallized by x‐ray and FSCA analysis. The strongly adhering metal on the film was believed to be responsible for the enhancement of electrical conductivity. The factors that affect the conductivity of metallized film were also studied.
Effect of mica on the curing behavior of an amine‐cured epoxy system: Differential scanning calorimetric studies
Authors: Bajaj P. , Jha N. K. , Kumar R. Ananda
Published: April 2003

Differential scanning calorimetry has been used to follow the cure behavior of mica filled epoxy system using an aromatic diamine (4,4′‐diaminodiphenylmethane) as a crosslinking agent. Both dynamic and isothermal methods have been adopted. The effect of mica on the kinetic parameters and the Tg of the cured system has been studied. It was found that mica accelerates the curing process, and decreases the Tg of the fully cured system to some extent.
The separation of water–ethanol mixtures by pervaporation through hydrophilic—hydrophobic composite membranes
Authors: Ruckenstein E. , Park J. S.
Published: April 2003

A new kind of polymer composite membrane, which we refer as hydrophilic–hydrophobic composite membrane, is prepared by the concentrated emulsion polymerization method6,7 and employed to separate permselectively ethanol–water mixtures. This composite contains polyacrylamide as the dispersed phase and crosslinked polystyrene as the continuous phase. The swelling in water of this composite membrane is around 4 g water/g polymer and its swelling in ethanol is negligible. The permeation of the composite membrane by pervaporation decreases with increasing ethanol concentration in the feed and increases with increasing polyacrylamide fraction in the composite. The rate of permeation is in the range of 30–103 g/m2 h. The selectivity of the membrane ranges between 2 and 50 and increases with increasing ethanol concentration in the feed and increasing polyacrylamide fraction in the composite. The permeation increases and the selectivity decreases with increasing feed temperature. The activation energy of permeation varies between 1.8 and 4.9 kcal/mol, depending upon the compositions of the feed and membrane.
Evaluation of thermal history of polymeric films and fibers using DSC/TMA/DMA techniques
Authors: Khanna Y. P.
Published: April 2003

Determining the thermal history of a semicrystalline polymer is an area of extreme importance when it comes to understanding the structure‐propety relationships. For nylon 6 film and fiber products, we have shown that techniques such as differential scanning calorimetry (DSC), thermomechanical analysis (TMA), and dynamic mechanical analysis (DMA) can reveal the thermal history of the polymer. We believe that the basis of correlation between the heat setting (annealing) conditions and the thermal/mechanical data is the formation of microcrystallites within the amorphous phase upon thermal treatment. Based on a previously published X‐ray study, we must mention that a number of changes within the crystalline phase also occur concurrently during the heat setting process of nylon 6. DMA of a highly annealed nylon 6 has helped us identify a broad α‐relaxation in the vicinity of 170°C, tentatively assigned to the mobility of interfacial amorphous domains. We propose that the occurrence of α‐relaxation parallels the crystalline phase changes observed in X‐ray studies during the heat setting of nylon 6 products. Although most of the work presented in this manuscript is based on nylon 6, the proposed correlation between the thermal history and DSC/TMA/DMA techniques can be expected for any semicrystalline polymeric film or fiber.
Fluorosilicone antifoams
Authors: Owen Michael J. , Groh Julianne L.
Published: April 2003

Antifoam compositions for aqueous surfactants are usually emulsions of insoluble oils containing hydrophobic solids. The emulsion allows easy access to the aqueous environment. The oil droplets carry the solid particles to the foam interfaces by spreading, which also contributes to foam rupture. The particles provide a disruptive dewetting surface and may also adsorb the foam stabilizer. This theory requires both oil and solid to have lower surface tension than the foaming surfactant and explains the ineffectiveness of conventional silicone antifoams based on polydimethylsiloxane against silicone and fluorocarbon aqueous surfactants. Some fluorosilicones have lower surface tensions than polydimethylsiloxane and should produce more effective antifoams. To test this idea the liquid surface tensions of a series of fluorosilicone‐containing copolymers were measured. These fluids were formulated into antifoam compounds and emulsions and tested against selected surfactants. Equilibrium and dynamic surface tensions of these test surfactants were also measured. The new antifoams are more effective than conventional silicones against silicone surfactants but are ineffective against fluorosurfactants. The implication of these results on the spreading/dewetting theory is discussed.
Composites of starch and poly(ethylene‐co‐acrylic acid). Complexing between polymeric components
Authors: Fanta G. F. , Swanson C. L. , Doane W. M.
Published: April 2003

Extrusion‐blown film prepared from a semidry mixture of starch and poly(ethylene‐co‐acrylic acid) (EAA) cannot be sharply separated into its polymeric components by selective solvent extraction, and the two polymers have the outward appearance of being compatible. Also, the starch portion is resistant to enzyme attack, and starch domains are not visible by SEM. Further studies were therefore made on the starch–EAA system to determine reasons for the apparent compatibility between the two polymers, and evidence for polymer complex formation was obtained. Combination of aqueous ammonia solutions of starch and EAA led to an increase in viscosity, and a coprecipitate of starch and EAA separated from solution. Moreover, solvent extraction would not separate physical mixtures of starch and EAA prepared from aqueous solutions. Although both the linear (amylose) and branched (amylopectin) components of starch formed an apparent complex with EAA, a low molecular weight starch fraction and a high molecular weight dextran (a polysaccharide with α‐(1→6) linked glucopyranosyl units) did not. These observations support the theory that a helical inclusion complex is formed from starch and EAA, which is similar to the well‐known complexes produced from starch and fatty acids.
Processing–morphology–property relationships in epoxy resins containing “fortifiers”
Authors: Mijović Jovan
Published: April 2003

An investigation was carried out into the effect of an additive called “fortifier” on curing, morphology, and thermomechanical properties of epoxy resins. Differential scanning calorimetry, electron microscopy, and a series of mechanical measurements were performed on bifunctional and tetrafunctional formulations. It was found that the addition of fortifier resulted in an increase in the fracture surface roughness, the size of morphological inhomogeneities observed in the fractographs, and the ultimate tensile strength. At the same time, the glass transition temperature was found to decrease by at least 25°C in going from 0 to 15 phr of the fortifier in a formulation. The presence of fortifier had little effect on the rate of cure and on the strain energy release rate.