bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular weight distribution of an unsaturated polyester
Authors: Kaštánek Alois , Zelenka Jiří , Hájek Karel
Published: April 2003

A precipitation fractionation was carried out by the nonsolvent addition method of 60 g of an unsaturated polyester. The polyester was prepared by the generally known melt condensation of maleic anhydride, phtalic anhydride, ethylene glycol, and cyclohexanol. Number‐average molecular weights of fractions were determined by vapor pressure osmometry in acetone at 36°C. Polydispersities of fractions were evaluated by gelpermeation chromatography (GPC) measurements with tetrahydrofuran as solvent. They seem to be wider for fractions of higher molecular weights. By infrared spectroscopy the fractions were found not to have marked differences in chemical compositions. The obtained molecular weight distribution curve of the unsaturated polyester was found to be in good agreement with that expected from the theory of polycondensation kinetics. The small differences appear only in the low molecular weight range.
Effect of crystallinity of condensation polymers on platelet adhesion
Authors: Ogata Naoya , Sanui Kohei , Tanaka Hozumi , Takahashi Yoichi , Kitamura Eichi , Sakurai Yasuhisa , Okano Teruo , Kataoka Kazunori , Akaike Toshihiro
Published: April 2003

Various polyamides and polyesters having different numbers of methylene groups in their repeating units have been synthesized and their blood compatibilities have been evaluated in terms of the adhesion behavior of blood platelets on the surface of these condensation polymers by a micro‐sphere‐column method. The number of methylene groups in the repeating units of polyamides and polyesters influenced the adhesion behavior of platelets and there was an optimum number of methylene groups each in polyamides and polyesters. Poly(hexamethylene terephthalamide) and poly(pentamethylene terephthalate) adsorbed platelets in the smallest number in the polyamide and polyester series, respectively. Blood platelets were adsorbed on polyamides in smaller numbers than on corresponding polyesters. It was found that the platelet adhesion on the surface of polyamides and polyesters was closely related to their crystallinities and the number of the adsorbed platelets decreased linearly with increasing their relative crystallinity.
Development of automatic cross fractionation: Combination of crystallizability fractionation and molecular weight fractionation
Authors: Nakano Seikou , Goto Yukitaka
Published: April 2003

An automatic cross‐fractionation system is presented by combining a newly developed crystallizability fractionation device based on the principle of isothermal dissolution with a commercially available GPC. The detail design, procedure, and operation variables are described. The fractions eluted from the device are characterized by use of an infrared spectrometer and a differential scanning calorimeter for clearing the mechanism of it. As the result of the study, it is found that the system is very useful for characterizing semicrystalline polymers.
Cure kinetics of a low epoxide/hydroxyl group‐ratio bisphenol a epoxy resin–anhydride system by infrared absorption spectroscopy
Authors: Stevens Gary C.
Published: April 2003

An infrared absorption spectroscopy study of the curing kinetics of a low (1.12) epoxide/hydroxyl‐group ratio bisphenol A epoxy resin—phthalic anhydride system is reported. A full infrared peak assignment to molecular vibrational modes is given for the range 400 to 4000 cm−1, and the optical density behavior of all peaks during reaction is discussed in detail. Proposed rival reaction mechanisms are considered and their respective kinetic behavior discussed. The reaction was found to follow consecutive‐step addition esterification and simultaneous addition etherification, and epoxide—hydroxyl group and carboxylic acid dimer hydrogen bonding was found to occur. The reaction behavior supports a proposed hydroxyl group‐limited inhomogeneous bulk reaction mechanism of a colloid type.
Cure kinetics of a high epoxide/hydroxyl group‐ratio bisphenol a epoxy resin—anhydride system by infrared absorption spectroscopy
Authors: Stevens Gary C.
Published: April 2003

An infrared absorption spectroscopy study of the curing (gelation and postcure) kinetics of a high (4.7) epoxide/hydroxyl group‐ratio diglycidyl ether of bisphenol A (DGEBA)–mixed anhydride epoxy resin system is reported. Peak assignments to molecular vibrational modes are given for the range 400–4000 cm−1, and the optical density behavior of all peaks during reaction is discussed in detail. Chemical reaction was found to follow consecutive‐step addition esterification and simultaneous addition etherification. Epoxide hydroxyl‐group and carboxylic acid dimer hydrogen bonding was found to occur. The gelation phase of reaction is complex, exhibiting rapid initial hydroxyl–anhydride reactions followed by S‐shaped kinetics approaching an incompletely reacted limit. Postcure exhibits functional group kinetic behavior similar to that occurring in low epoxide/hydroxyl group‐ratio bisphenol A epoxy resin–phthalic anhydride systems and produces similar final chemical structures. The reaction behavior of low and high epoxide/hydroxyl group‐ratio bisphenol A epoxy resin–anhydride systems arises from an hydroxyl group‐limited inhomogeneous reaction mechanism involving bisphenol A epoxy resin molecular aggregates. The importance of free hydroxyl group content is discussed.
The simulation of hydrolytic polymerization of ϵ‐caprolactam in various reactors
Authors: Tai Kazuo , Arai Yoshihiro , Tagawa Takashi
Published: April 2003

The concrete simulation models dealing with the kinetic behavior of the hydrolytic polymerization of ϵ‐caprolactam (CL) in various polymerization reactors used in the industry were described, and the method for their numerical solutions was presented. The characteristic data of the polymerization such as the concentrations of CL, end group, water, ϵ‐aminocaproic acid, cyclic dimer, and the hot‐water‐soluble component, conversion, number average, and weight average molecular weights, and solution and melt viscosities can be calculated at every stage of the polymerization reaction, at every part of the reactors, and/or at the outlet of the reactors. The calculated values based upon the models were found to be quite compatible with the observed values for the reactors. The applicability of the technique was well confirmed for the quality control, process control, modification of existing plants, and development of new chemical process plants.
On the crystallinity of poly(alkylbenzimidazole) salts
Authors: Aharoni Shaul M.
Published: April 2003

Poly(alkyldibenzimidazole) and poly(alkylbisbenzimidazole) having five, six, seven, and eight methylene groups in each repeat unit were synthesized. Salts of these polymers with strong acids, whose pK is 4.00 or less, were prepared. Weaker acids do not form salts with the poly(alkylbenzimidazole)s. It was found that polymers having an even number of methylene groups per repeat unit tend to form crystalline salts while those polymers having an odd number of methylene groups from only amorphous salts. From among the crystalline salts, those containing poly(bisbenzimidazole)s are more crystalline than their analogous poly(dibenzimidazole)s.
The effect of casting solvent and water on gas permeability of poly(γ‐methyl L‐glutamate) membrane
Authors: Minoura Norihiko
Published: April 2003

Gas permeability of poly(γ‐methyl L‐glutamate) (PMLG) membranes prepared by using dichlorethane, trifluoroacetic acid, and formic acid as solvents was studied. The membranes prepared by casting dichloroethane and trifluoroacetic acid solutions of the polymer, designated as PMLG—DCE and PMLG—TFA, respectively, had α‐helical structures according to infrared absorption spectra, while the membranes prepared by allowing the PMLG—TFA membranes to swell in formic acid, designated as PMLG—FA, had mainly a β‐sheet structure. The diffusion coefficients of each gas studied for PMLG—DCE, PMLG—TFA, and PMLG—FA decreased in that order, and the apparent activation energies of diffusion increased in that order. The apparent heats of solution for Ne,O2, N2, and CO2 were negative in PMLG—FA. These results were discussed in connection with the molecular conformations of PMLG in the membranes. It is suggested that the diffusion of gases in PMLG—DCE takes place in the side‐chain regions between helices, while in PMLG—FA the diffusion occurs across the polymer main chain whose mobility is depressed by the intermolecular hydrogen bonds. The effect of water on oxygen permeability of PMLG—DCE was small; on the contrary that of PMLG—FA was very large. Furthermore, it is assumed that the random‐coil conformation partly exists in PMLG—TFA.
Graft polymerization of acrylic acid onto polyethylene film by preirradiation method. II. Effects of oxygen at irradiation, storage time after irradiation, mohr's salt, and ethylene dichloride
Authors: Ishigaki Isao , Sugo Takanobu , Takayama Takashi , Okada Toshio , Okamoto Jiro , Machi Sueo
Published: April 2003

In the grafting of acrylic acid onto polyethylene by preirradiation method, the irradiation in air gave a higher rate of grafting than in N2, since the diffusion rate of monomer is larger for less crosslinked polyethylene. The rate of grafting decreased with increasing time of storaging polyethylene because of the decay of trapped radicals. The effects of storage conditions on the grafting activity was reasonably interpreted by assuming that grafting is predominantly controlled by both concentration of trapped radicals and monomer diffusibility in the polymer matrix. Mohr's salt was found to depress the homopolymerization of acrylic acid without marked change of grafting rate. The rate of grafting was increased by the addition of ethylene dichloride due to the increase in monomer diffusion.
New epoxy resins. I. The stability of epoxy–trialkoxyboroxines triaryloxyboroxine system
Authors: Chen C. S. , Bulkin B. J. , Pearce E. M.
Published: April 2003

A polymer with high aromaticity and/or cyclic ring structures chain backbone usually has high heat, thermal, and flame resistance. Two diglycidyl ethers of bisphenols were prepared from 4,4′ isopropylidenediphenol (DGEBA) and 9,9‐bis(4‐hydroxyphenyl) fluorene (DGEBF) for evaluation. Four boroxines—trimethoxyboroxine (TMB), triethoxyboroxine (TEB), triisopropoxyboroxine (TIPB) and triphenoxyboroxine (TPB)—were used as the curing agents. DGEBA and DGEBF cured with various boroxines indicate that the trend for their respective glass transition temperature (Tg's), degradation temperatures (Td's), and gel fractions are TMB‐cured epoxy ≈ TEB‐cured epoxy < TIPB cured epoxy < TPB cured epoxy. The DGEBF system usually has a higherTg,Td, gel fraction, oxygen index (OI), and char yield than the related DGEBA system. DGEBF/DGEBA (80/20 mol ratio) shows a synergistic effect in regard to char formation. This effect exists not only in the copolymer system but also in blended homopolymers of the separately cured resins. A modified mechanism for the polymerization of phenyl glycidyl ether (PGE) with TMB has been proposed.
Mass transfer effects in polycondensation reactors wherein functional groups are not equally reactive
Authors: Gupta Santosh K. , Agarwalla N. L. , Kumar Anil
Published: April 2003

Three simplified models of polycondensation reactors are considered in which the condensation product is continuously removed by application of vacuum. Reversible polycondensation reactions of monomers violating the equal reactivity hypothesis have been simulated in these reactors. The effect of various rate and reactor design variables on the molecular weight distribution (MWD) and its moments is studed. It is observed that when the reverse reactions are rapid, the results are fairly sensitive to the level of vacuum applied and to the mass transfer resistance; whereas when the forward reactions predominate, results lie very close to earlier plots for the corresponding irreversible polymerizations. These reactor variables then have relatively small influence on the MWD. Splitting of the MWD curves for odd and even values on n is observed under certain conditions, the effects being more pronounced in the presence of mass transfer than in its absence.
Emissivity of chlorinated polyethylene
Authors: Fujikura Yoshiaki , Suzuki Takanori , Matsumoto Masakazu
Published: April 2003

The emissivity of chlorinated polyethylene containing varying amounts of combined chlorine has been investigated. It was found that the emissivity of these compounds increases significantly with increase in chlorination.
Drawing rate effects on morphological parameters in nylon‐6, PET, and PBT filaments
Authors: Song John W. , Abhiraman A. S. , Rickards Alan P.
Published: April 2003

Influence of drawing velocity on morphological parameters of nylon‐6, PET, and PBT filaments has been studied. The drawing was carried out at approximately 20°C above the effective glass transition temperature of these materials. The results are explained in terms of drawing‐induced changes in temperature and in rate of crystallization.
Effect of an additive on the radiation resistance of polyethylene and ethylene–propylene copolymer
Authors: Fujimura Takashi , Arakawa Kazuo , Hayakawa Naohiro , Kuriyama Isamu
Published: April 2003

In low‐density polyethylene containing the additive propylfluorancene, radiation energy received by polyethylene is transferred to propylfluorancence, and the production of radicals at 77 K in polyethylene is suppressed. Propylfluoranncene also increases the rate of the decay of radicals of polyethylene at room temperature. The depression of radical production and accelaration of radical decay at room temperature results in the depression of gas production and crosslinks at room temperature in low‐density polyethylene containing propylfluorancene. Similar results were obtained in ethylen–propylene copolymer containing the same additive.
Structurally bound stabilizers: Melt grafting of UV stabilizers onto polypropylene, polyethylene, and polystyrene
Authors: Sharma Y. N. , Naqvi M. K. , Gawande P. S. , Bhardwaj I. S.
Published: April 2003

Monomeric ultraviolet stabilizers, 2‐hydroxy‐4‐methacryloyloxy benzophenone and 2‐hydroxy‐4‐acryloyloxy benzophenone were synthesized by a modified process. These reactive UV stabilizers were grafted onto the backbone of polypropylene (PP), low‐density polyethylene (LDPE), and polystyrene (PS) by melt processing in the mixer of Brabender Plasticorder. An infrared spectroscopic method was standardized for the quantitative determination of the extent grafting of these additives on the polymer backbone. Grafting of both the additives occurred in the order PS > LDPE > PP. Methacryloxy derivative of benzophenone was found to be more reactive towards the polymers studied than the acryloxy derivative.
An interpolymer anionic composite reverse osmosis membrane derived from poly(vinyl alcohol) and poly(styrene sulfonic acid)
Authors: Koyama Kiyoshi , Okada Minoru , Nishimura Masato
Published: April 2003

An interpolymer anionic composite membrane for reverse osmosis was prepared from poly(vinyl alcohol) and poly(styrene sulfonic acid). The effects of composition of a casting solution, heat‐curing periods, and casting thickness on the reverse osmosis performance of resulted membranes have been examined. A mixture of water and ethyl alcohol (12/7, wt %) was found to be a proper solvent for casting an interpolymer membrane on the supporter. The composite membrane was formed by casting the polymer solution in ultrathin film on a microporous polypropylene supporter, evaporating the solvent, and heat‐curing at 120°C for a proper period. the optimum composition of a casting solution was as follows: wt % of poly(vinyl alcohol)/poly(styrene sulfonic acid)/solvent was 3/2/95. The membrane heat‐cured at 120°C for 2 h has a good performance for reverse osmosis, viz., water flux of 9.1–28.4 L/m2.h at salt rejection level of 88.1–93.4% under applied pressure of 80 kg/cm2 with 0.5% NaCl aqueous solution. The formation mechanism of a water‐insoluble membrane was discussed.
New epoxy resins. II. The preparation, characterization, and curing of epoxy resins and their copolymers
Authors: Chen C. S. , Bulkin B. J. , Pearce E. M.
Published: April 2003

A polymer having high aromaticity and/or cyclic ring structures in the chain backbone usually gives high heat resistance and flame resistance. Five glycidyl ether‐type epoxy resins are prepared from bisphenol A (DGEBA), 9,9‐bis(4‐hydroxyphenyl)fluorene (DGEBF), 3,6‐dihydroxyspiro‐[fluorene‐9,9′‐xanthane] (DGEFX), 10,10‐bis(4‐hydroxyphenyl) anthrone (DGEA), and 9,9,10,10‐tetrakis(4‐hydroxyphenyl)anthracene (TGETA) in order to study structure–thermal stability–flame resistance property relationships. In this study, trimethoxyboroxine (TMB) and diaminodiphenylsulfone (DDS) are employed as the curing agents. The char yield at 700°C under a nitrogen atmosphere and the glass transition temperature (Tg) for the uncured resins decrease according to the sequence TGETA > DGEFX > DGEA > DGEBF > DGEBA. The Tg values for these cured epoxy resins are DGEBA < DGEBF < DGEFX < DGEA. A Tg for the TGETA is not obtainable but would be expected to be the highest. The char yields at 700°C of these cured epoxy resins have the same trend as the uncured resins. DGEBF, DGEFX, DGEA, and TGETA added to the DGEBA system show increases in the char yield, Tg, and oxygen index with increasing concentration of these novel epoxy resins.
Degradation studies of plasticized PVC. I. Multiple internal reflection infrared spectroscopy
Authors: Hill C. A. S.
Published: April 2003

Multiple internal reflection infrared spectroscopy (MIR) was used to study surface degradation in commercial and laboratory prepared plasticized PVC samples. Samples were subjected to accelerated (UV exposure) and natural weathering. Ultraviolet‐exposed samples show peak formation at 3200 cm−1 (OH), and 1400cm−1(CH bend), as well as increased absorption at 1720 cm−1 (CO). Outdoor‐exposed samples show essentially similar changes, but the variation in peak ratio shows large variations of a random nature; it has been proposed that rainfall has a major influence on surface plasticizer concentration.
Determination of the structural configuration of cresol–novolak resins by 13C NMR spectroscopy
Authors: Carothers J. A. , Gipstein E. , Fleming W. W. , Tompkins T.
Published: April 2003

13C NMR spectroscopy was used to investigate the structures of a series of pure isomeric cresylic novolak resins. Chemical shifts were measured and assigned, and end groups were distinguished from the central repeat units of the chains. Based on these measurements, the number average molecular weight of the para‐cresylic oligomer was determined. A comparison of the 13C decoupled and coupled spectra of the three isomeric resins indicates that the para isomer has a linear, ordered structure in which the aromatic rings are linked only by ortho–ortho′ methylene‐bridging groups. The structures of the ortho and meta isomers are more complex and contain ortho–ortho′, ortho–para′, and para–para′ methylene bridges.
Cotton cellulose: Enzyme adsorption and enzymatic hydrolysis
Authors: Beltrame P. L. , Carniti P. , Focher B. , Marzetti A. , Cattaneo M.
Published: April 2003

Adsorption of a crude cellulase complex from Trichoderma viride on variously pretreated cotton celluloses has been studied in the framework of the Langmuir approach, in the temperature range 2–8°C. The saturation amount of adsorbed enzyme has been related to their susceptibility to hydrolysis. In every case the adsorption process was found to be faster by 2–3 orders of magnitude than the hydrolysis step to give end products. For one substrate, the Langmuir parameters were found to be fairly well correlated with the value of the Michaelis constant Km, measured for its enzymatic hydrolysis, and the adsorptive complex (ES)ad was indistinguishable from the complex (ES) of the Michaelis–Menten model for the hydrolysis.
Crosslinking of unsaturated polyester resins by combinations of vinyl esters and methacrylates
Authors: Froehling Peter E.
Published: April 2003

The replacement of styrene by other crosslinking monomers in unsaturated polyester resins has been investigated because of the possible toxicity of this monomer and the strong smoke evolution of burning polyester materials. A theoretical study has been carried out to provide criteria for the applicability of classes of monomers in polyester curing. From this study it appeared that vinyl esters, vinyl ethers, N‐vinyl lactams, and styrenes are suitable, whereas acrylic and methacrylic esters and allylic or olefinic compounds are not. Combinations of vinyl esters and (meth)acrylic esters of polyols should generate IPN‐like structures. Polyesters cured by this combination of monomers gave materials with increased stiffness and strength relative to those obtained with the separate monomers and on the same level as styrene‐cured polyesters.
An analysis of transients in primary nucleation
Authors: McHugh A. J.
Published: April 2003

An analysis is presented of the equations governing time dependent primary nucleation in polymer crystallization. Solution of the one‐dimensional diffusion equation for the transient formation of embryos consisting of either chain folded or bundlelike nuclei, near the critical point, leads to a simple expression for estimating the transient time constant. Numerical estimates demonstrate that transient processes are unimportant in solution crystallization and potentially important in melt crystallization unless heterogeneities are present.
Graft copolymerization of methyl methacrylate onto poly(ethylene terephthalate) fibers using thallium(III) ions as initiator
Authors: Misra Sivananda , Nayak Padma L. , Sahu Gangadhar
Published: April 2003

Graft copolymerization of methyl methacrylate onto poly(ethylene terephthalate) fibers was investigated in aqueous perchloric acid medium using thallium(III) ions as initiator. The rate of grafting was evaluated varying the concentrations of monomer, initiator, and acid and the temperature. The rate of grafting was found to increase with increase in monomer and initiator concentrations. The graft yield was found to increase with increase in the acid concentration up to 0.49 mL−1, and beyond this concentration it was found to decrease. Increase in temperature resulted in increase in graft yield. From the Arrhenius plot the overall activation energy was found to be 3.76 kcal/mol. The effect of additives such as swelling agents, inorganic salts, different solvents, and inhibitors on graft yield was studied. A suitable kinetic scheme is proposed and a rate equation derived.
Surface‐modified kevlar fiber‐reinforced polyethylene and ionomer
Authors: Takayanagi Motowo , Kajiyama Tisato , Katayose Teruo
Published: April 2003

The surface of poly(p‐phenylene terephthalamide) (PPTA) fiber was modified by the polymer reaction via the metalation reaction in demethyl sulfoxide to provide the fiber surface with several functional groups such as the n‐octadecyl group, carboxymethyl group, and acrylonitrile. The discontinuous fibers thus modified could be isotropically dispersed in polyethylene and ionomer. The composite of ionomer and random‐in‐plane oriented discontinuous PPTA fibers with the surface modified by carboxymethyl groups was remarkably improved in its mechanical properties, and the fiber efficiency factors of about 0.4 for both strength and modulus are comparable to the values in the composite of unidirectionally oriented discontinuous PPTA fibers and ionomer. The heat resistance of ionomer was also greatly improved by the presence of this surface modified PPTA fibers, even with volume fractions as low as 2.2%.
Pesticide encapsulation using a starch–borate complex as wall material
Authors: Trimnell D. , Shasha B. S. , Wing R. E. , Otey F. H.
Published: April 2003

A new technique has been developed for encapsulating pesticides for controlled release. The method consists in mixing starch, pesticide, and water; adding alkali to gelatinize the starch; and treating the mixture with boric acid. The solid product is a starch–borate adduct, entrapping the pesticide within small cells. Initially, the adduct is a rubbery gel which, when treated with alcohol or ground with additional pearl starch, yields particles suitable for drying to the 10–35‐mesh range. When the starch is used to break up the gel, the technique is useful for retaining water‐soluble compounds. Water‐insoluble pesticides, emulsifiable concentrates, and wettable powders are encapsulated and recovered in high yields. Acid‐labile pesticides such as diazinon are stable in the borate gel. The process was scaled up successfully by use of a double planetary mixer.
Effect of large dosage irradiation in vacuo on polyethylene
Authors: Fujimura Takashi , Hayakawa Naohiro , Kuriyama Isamu
Published: April 2003

The effect of large dosage irradiation in vacuo on polyethylene was investigated by the method of double irradiation. Polyethylene was first irradiated with γ‐rays to a dosage of several hundred Mrad in vacuo at 298°K. The formed radicals were destoryed, and the polymer, changed chemically and morphologically, was irradiated again in vacuo at 77°K with a dose of 12.7 Mrad. The thermal decay of radicals produced in polyethylene by the second irradiation was investigated. The results show that many double bonds are formed in the sample irradiated to several hundred Mrad on the first irradiation. Alkyl radicals produced by the second irradiation react with these double bonds yielded by the first irradiation to form a large number of allyl radicals. These allyl radicals are much more stable than alkyl radicals radicals in vacuo at 298°K. In a sample not exposed to the first irradiation, almost all radicals formed by the second irradiation decay to form stable products. Crosslinks formed by a large amount of irradiation make the polyethylene matrix more rigid. This rigidity slows down the radical decay. These results suggest that the rate of radical accumulation in polyethylene irradiated in vacuo increases as the dosage increases.
Effect of heat treatment on the dielectric relaxation of polyacrylonitrile. II. Heat treatment under vacuum and in air
Authors: Gupta A. K. , Singhal R. P. , Maiti A. K. , Agarwal V. K.
Published: April 2003

Dielectric relaxation, infrared spectra, and X‐ray diffraction data of polyacrylonitrile (PAN) heat treated at 120°C in air and under vacuum and of the untreated PAN are reported. The heat treatment resulted in (1) lowering of dielectric constant increment, dielectric dissipation factor, and increase in relaxation temperature and glass transition temperature; (2) lowering of the intensity of CN stretching band in the infrared spectra; and (3) increase in degree of order of the X‐ray diffraction results. The changes produced by heat treatment under vacuum are found greater than those produced by heat treatment in air, which suggests that the observed effect is not caused by chemical changes in the PAN molecule under heat treatment. Interpretation of these results is attempted on the basis of the difference in the degree of bound nitrille group pairs (bound through intermolecular dipole–dipole interactions) in the structure of PAN heat treated under the different conditions.
A mechanism for the consolidation of the structure of clay–latex coatings
Authors: Watanabe J. , Lepoutre P.
Published: April 2003

Attempts have been made to follow the process of consolidation, during drying, of the structure of a paper coating based on clay and latex by the electron microscope observation, and the analysis of coatings quenched by freezing at various stages and freeze‐dried. Three phases are considered, separated by two critical concentrations. At the first critical concentration (FCC), a 3‐dimensional network is formed, and particle motion is greatly restricted. The water–air interface recedes into the surface capillaries, creating a capillary pressure that causes a shrinkage of the 3‐dimensional network until a second critical concentration (SCC) is reached at which the network is fixed and air enters the rigid structure. Latex stiffness and colloidal interactions influence the critical concentrations. The latex coalescence process has been observed to take place over a relatively narrow concentration range after the FCC and is completed at the SCC.
Pervaporation of benzene–cyclohexane mixture by poly(γ‐methyl L‐glutamate) membrane and synergetic effect of their mixture on diffusion rate
Authors: Suzuki Fumio , Onozato Kenji
Published: April 2003

The pervaporation of binary liquids mixture of benzene and cyclohexane was examined by use of poly(γ‐methyl L‐glutamate) (PMLG) membrane. The permeation rate–time curve for each of benzene and cyclohexane from their mixtures changed to the longer times side by increasing the cyclohexane in the mixtures. t1/2 (the time required to reach a half‐value of the steady state permeation rate) for the each component increased exponentially with increasing of cyclohexane, which has a smaller plasticizing effect on PMLG membrane than benzene, in the mixtures. The apparent diffusion coefficients, obtained from the steady state permeation and the sorption experiments, for benzene–PMLG and cyclohexane–PMLG are dependent exponentially on the sorbed amounts of benzene. This result was explained on the bases that the diffusion of cyclohexane was enhanced synergetically with benzene coexisting in the system. This effect influenced negatively the separation of the liquids mixture by pervaporation.
Graft polymerization of acrylonitrile and methyl acrylate onto hemicellulose
Authors: Fanta G. F. , Burr R. C. , Doane W. M.
Published: April 2003

Graft polymerizations of acrylonitrile onto both a commercial larchwood hemicellulose and a purified (low lignin) wheat straw hemicellulose could be initiated by ceric ammonium nitrate. The resulting hemicellulose‐g‐polyacrylonitrile (PAN) copolymers were fractionated by extraction at room temperature with dimethylformamide and dimethylsulfoxide. Fractions were characterized by determining both the wt % PAN in each polymer fraction and the molecular weight of grafted PAN. Saponification of the PAN component of hemicellulose‐g‐PAN gave a water‐dispersible graft copolymer with good thickening properties for water systems. An absorbent polymer, similar to the starch‐based absorbents (Super Slurpers), was produced when saponified hemicellulose‐g‐PAN was isolated by methanol precipitation and then dried. Larchwood hemicellulose was also graft‐polymerized with methyl acrylate using ceric ammonium nitrate initiation, and the hemicellulose‐g‐poly(methyl acrylate) was extrusion‐processed into a tough, leathery plastic. Although ceric ammonium nitrate could be used as an initiator for graft polymerizations onto low‐lignin hemicelluloses, it was inert with crude wheat straw hemicellulose containing 11% lignin. The ferrous sulfate–hydrogen peroxide redox system was used to initiate graft polymerizations onto this high‐lignin material, and properties of the resulting hemicellulose‐g‐poly(methyl acrylate) and saponified hemicellulose‐g‐PAN graft copolymers were evaluated.
Studies of interaction in silica/styrene–butadiene copolymers
Authors: Díaz‐Barrios Antonio , Paredes Edgar
Published: April 2003

Adsorption, bound rubber, mechanical properties, and electron microscopy determinations were carried out in silica/styrene–butadiene copolymers. These studies reveal equivalent trends with varying copolymer composition. Thus, when the copolymer is richer in styrene, adsorbance and bound rubber increase, the stress softening effect becomes more remarkable, and silica is more uniformly dispersed in the elastomeric matrix. These results indicate that polymer–filler interaction becomes stronger when the content of styrene in the elastomer is increased. This interaction does not appear to be explicitly reflected in the other mechanical properties studied.
Studies on melt spinning. VIII. Transfer function approach
Authors: Kase Susumu , Araki Masashi
Published: April 2003

Transfer function analyses were carried out on a linearized perturbation model of melt spinning previously developed. Results are as follows. (1) Formal proof was obtained of the criterion of spinline stability stated in terms of transfer function. (2) A new concise statement of the stability criterion was obtained: the spinline is stable when the transfer function G2(s) connecting the spinline tension to the spinline velocity does not have a zero in the right‐hand half of the complex s plane. (3) Effects of various external disturbances on filament unevenness were predicted theoretically by expressing the transfer function between each disturbance input and cross‐sectional area at take‐up in the form of frequency response Bode diagrams.
Ultrasonically delaminated and coarse mica particles as reinforcements for polypropylene
Authors: Tausz Susan E. , Chaffey Charles E.
Published: April 2003

The effect of the size of mica platelets used, at 30% by mass, to reinforce polypropylene was studied by comparing ultrasonically delaminated mica (diameter 5μ aspect ratio about 40) with a coarser mica (150–420μ) with and without the coupling agent 3‐(triethoxysilyl)‐1‐propanamine (Union Carbide A‐1100). Reducing the particle size of the mica (treated with coupling agent) significantly increased the tensile modulus and strength but did not affect elongation at break; it gave a small improvement in Izod impact strength; the heat distortion temperature was lower and the melt flow index was increased. Dynamic mechanical evaluation (Rheovibron) was done with a series of coarse micas (>44μ, 45–150μ, 150–250μ, and one with a broad distribution around 100μ), and an ultrasonically delaminated mica made in a continuous process (>20μ), all treated with N‐(4‐vinylphenyl) methyl‐N′‐(3‐trimethoxysilylpropyl)ethylenediamine (Dow Corning Z‐6032), at 20% by mass in polypropylene. Except for the disappearance of a peak at 0°C in the loss tangent due to the glass transition, the composite with delaminated mica did not differ from pure polypropylene, melting at 175°C. Use of the coarser micas raised the melting temperature to 200°C, increased the storage modulus, and lowered the loss tangent in the case of the three fractionated samples. The results were concordant with theories of reinforcement and microheology. The hoped‐for improvement in some properties on changing to the finer mica may not have been realized because of incomplete dispersion.
The effects of run‐in on rubber friction
Authors: Cooper R. P. , Ellis Bryan
Published: April 2003

Experimental measurement of the change in coefficient of friction with sliding distance of a carbon‐black‐reinforced rubber on either glass or Perspex surfaces increases monotonically to a constant value as required by Saibel's theory. However, this general stochastic model does not allow for a fully satisfactory physical interpretation of the effects of run‐in on rubber friction. The present measurements for rubber on a glass surface agree well with those of Roth and co‐workers reported many years ago. The observation of these effects on Perspex does not appear to have been reported previously. It is found that a material, probably stearic acid or zinc stearate, is deposited from the rubber onto a glass surface when the rubber slides on it.
Studies on synthetic polymer plates with high surface energy. III. Diethylene glycol bis(allyl carbonate)–unsaturated sulfonic acid system
Authors: Kaneko Norio , Ohtsuka Yasuji
Published: April 2003

Synthetic polymer plates (GPs) with high surface energy were prepared by the two‐step copolymerization process previously reported, using diethylene glycol bis(allyl carbonate) (CR‐39) as M1 monomer and unsaturated sulfonates [sodium vinyl sulfonate (VS−Na+), potassium styrene sulfonate (StS−K+), and sodium 2‐sulfoethyl methacrylate (SEM−Na+)] as M2 monomer. The contact angle (θH) of water for the acid‐treated (immersed in an aqueous 0.1 N HCl solution for 2 h) GPs decreased in the order StS−K+, VS−Na+, and SEM−Na+. In the case of M2 = SEM−Na+, the θH value was about 20°. By adding NaCl in the immersion solution and changing the pH of the immersion solution, the θH values for the CR‐39–SEM−Na+ GPs were lowered to 18.9 and 13.1°, respectively. The θH values for the above GPs were smaller than those for the CR‐39–acrylic acid or the CR‐39–methacrylic acid GPs in the previous report, whereas the contact angle (θNa) of water for the former after alkali treatment (immersed in an aqueous 0.1 N NaOH solution for 2h) was larger than those for the latter. The former had durability of water wettability superior to the latter because of the difference in dissociation characteristic of the respective functional group.
Some properties and chemical structure of phenolic resins and their derivatives
Authors: Roczniak Krystyna , Biernacka Teresa , Skarżyński Maciej
Published: April 2003

Some physical and chemical properties of novolac and resole resins are described, IR spectra are given, and average structures of the examined resins are proposed. It was supposed that the gelation kinetics depend on the ratio of the reagents and on the structure of the resin.
Deformation band studies of axially compressed poly(p‐phenylene terephthalamide) fiber
Authors: Takahashi T. , Miura M. , Sakurai K.
Published: April 2003

Deformation mechanism of poly(p‐phenylene terephthalamide) (PPTA) fiber during axial compression was studied. PPTA fibers were embedded in resin and axialy compressed in a tensile machine. PPTA fibers were then taken out from resin at various stages of compression. Kink band formation was examined by means of polarizing microscopy, X‐ray diffraction (WAXD), electron diffraction (ED), and electron microscopy. WAXD pattern of seriously compressed PPTA fiber shows that (200) reflection spots and arcs appear on the equator and meridian respectively. On the other hand, (110) reflection spots are confined to the equator. PPTA fiber could be splitted tangentially and radially into two kinds of thin fibrillar fragments (I and II) which reveal two distinct types of kink band and ED pattern. In fragment I obtained by tangential splitting, kink bands are formed at about 55° with respect to fibril axis, whereas in fragment II obtained by radial splitting kink bands are formed perpendicular to the fibril axis. These results were confirmed by ED studies. It was assumed that slip of (200) planes containing hydrogen bonded sheets as well as intermicrofibril slip plays an important role in the deformation of PPTA fiber during axial compression.
Rheology of unsaturated polyester resins. III. Effects of filler and low‐profile additive on the thickening behavior of unsaturated polyester resin
Authors: Kwok‐Wailem  , Han Chang Dae
Published: April 2003

An investigation was made of the rheological behavior of unsaturated polyester resin during thickening in the presence of filler or low‐profile additive alone and, also, in the presence of both filler and low‐profile additive. For the study, two different types of filler (CaCO3 and clay) and two different types of low‐profile additive (PMMA and PVAc) were evaluated. Compared to the resin/thickener system, the resin/filler/thickener system exhibits shear‐thinning behavior as thickening progresses, and gives rise to smaller normal stress effects. On the other hand, the resin/low‐profile additive/thickener system exhibits two distinct Newtonian regimes in the viscosity‐shear stress curves and gives rise to larger normal stress effects. The viscosity behavior of the resin/filler/low‐profile additive/thickener system was found to be very similar to that of the resin/low‐profile additive/thickener system. In all cases, when the first normal stress difference was plotted against the shear stress, a correlation was obtained which was independent of thickening period. This behavior was exactly the same as for thickening polyester resin alone, as discussed in Part II of this series.
Studies of the polymerization of diallyl compounds. XXXVIII. Telomerization of diallyl aromatic dicarboxylates in the presence of carbon tetrabromide
Authors: Matsumoto Akira , Nakane Toshio , Oiwa Masayoshi
Published: April 2003

Radical telomerization of diallyl aromatic dicarboxylates, including diallyl phthalate (DAP) and diallyl terephthalate (DAT), was investigated in detail in the presence of CBr4 as a telogen. Telomer yield could be accurately determined by a subsidiary GPC measurement in conjunction with a precipitation method. Telomerization kinetics of diallyl compound in the presence of CBr4 was discussed and the chain transfer constant CCBr4 (= ktr/kp) was estimated to be 57.9 and 53.8 for DAP and DAT, respectively, the values which correspond to those for one functional group of diallyl compound. The degree of polymerization was significantly dependent on conversion as consequences of the fast consumption of CBr4 and the occurrence of crosslinking reaction. The rate of polymerization was enhanced with the added amount of CBr4, being ascribable to the replacement of the degradative chain transfer by the chain transfer to CBr4, the latter which yields active tribromomethyl radical in lieu of less active allyl radical. Gelation was delayed with an increase in the added amount of CBr4. Preparation of telomer in high yield and its applicability are finally discussed.
Phosphorus‐Containing polymers. I. Low temperature polycondensation of phenylphosphonic dichloride with bisphenols
Authors: Kim Ki‐Soo
Published: April 2003

This paper describes the synthesis of aryl polyphosphonates from the reactions of phenylphosphonic dichloride [benzene phosphorus oxydichloride (BPOD)] with 4,4′‐thiodiphenol (TDP) and with 4,4′‐sulfonyldiphenol (SDP) employing a dry chlorinated hydrocarbon polymerization solvent, an amine acid acceptor and under low temperature conditions. The glass transition temperatures of the polymers from BPOD/TDP are 146°C and 83°C, respectively, and the polymers begin to lose weight at about 395°C in a nitrogen atmosphere. These polymers have good flame retardancy (FR), as indicated by high limiting oxygen indices (LOI) of 50–60. Thermoplastic polybutylene terephthalate containing 7% BPOD/SDP or BPOD/TDP polymer as an FR additive has LOI values of 29 and 30, respectively.
UV absorber progenitors: Photo‐fries rearrangements of sulfonate esters of hydroxyphenylbenzotriazoles
Authors: Olson Daniel R.
Published: April 2003

Benzenesulfonate esters of hydroxyphenylbenzotriazole UV absorbers are described as UV absorber progenitors which can be used in UV‐curable coating formulations. During UV exposure, they undergo a photo‐Fries rearrangement to form the corresponding o‐benzenesulfonyl phenol derivatives. These derivatives are formed in good chemical yield during bulk solution photolyses and are also readily formed in polymer films during exposure to sunlight. The reaction is specific for benzenesulfonate esters; little or no rearrangement takes place with benzyl, naphthyl, or alkylsulfonate esters or with benzoate esters.
Thermal decomposition kinetics of iodine‐doped polyacetylene in vacuum
Authors: Osterholm J.‐E. , Yasuda H. K. , Levenson L. L.
Published: April 2003

The thermal stability of iodine‐doped polyacetylene films, (CHIy)x, has been studied by means of electrical conductivity measurements, measurements on weight loss, and mass spectrometric analysis of desorbing species. When heated between room temperature and 125°C in vacuum, these films proved to be of poor thermal stability, being unstable at temperatures above 20°C. During the thermal treatments, molecular iodine desorbs from the films, resulting in an appreciable dopant weight loss with accompanying decrease in the electrical conductivity. The decomposition process does not follow simple kinetics.
Preparation of photoresponsive polymeric adsorbent containing amphiphilic polymer with azobenzene moiety and its application for cell adhesion chromatography
Authors: Ishihara Kazuhiko , Kim Munsok , Shinohara Isao , Okano Teruo , Kataoka Kazunori , Sakurai Yasuhisa
Published: April 2003

In order to develop a new type column chromatography, a polymeric adsorbent was prepared by grafting a photoresponsive polymer containing an azobenzene moiety on the surface of controlled pore glass beads. The polarity of the surface of the polymeric adsorbent was increased by UV irradiation because of trans–cis isomerization of azobenzene moiety. Adhesion chromatography of erythrocytes was carried out using the photoresponsive polymeric adsorbent. The erythrocytes were adhered to the adsorbent in the dark and separated from the adsorbent by UV irradiation. This behavior appears to be caused by the photoresponse of the polarity change on the surface of the polymeric adsorbent. The morphology of the erythrocytes which adhered on the surface of the photoresponsive polymeric adsorbent remained unchanged both in the dark and after UV irradiation. The amount of erythrocytes which adhered to the adsorbent increased with increasing the molecular weight of the grafted polymer and the hydrophobicity of the surface.
Studies of synthesis and permeabilities of special polymer membranes. LI. Active transport of halogen ions through chitosan membranes
Authors: Uragami Tadashi , Yoshida Fumihiko , Sugihara Mizuho
Published: April 2003

Anion exchange membranes containing amino groups, insoluble in acidic and alkaline aqueous solutions, were prepared from chitosan, poly(vinyl alcohol), and glutaraldehyde. Using the membrane in a diaphragm cell, one side being adjusted to be acidic and the other alkaline, it was possible to transport actively halogen ions through the membrane from the acidic side to the alkaline side against the concentration gradient between both sides of the membrane. The active transport of halogen ions through the membrane was significantly influenced by the pH difference and electric potential difference between both sides of the membrane.
Swelling behavior of cotton fibers in benzylamine and 4‐amino acetophenone
Authors: Lokhande H. T. , Nikte V. V. , Shukla S. R.
Published: April 2003

Swelling and decrystallizing action of aqueous solutions of benzylamine and mixtures of 4‐amino acetophenone with methanol was studied on cotton fibers. The extent and type of swelling were studied by determining various characteristics of the swollen cotton, viz., moisture regain, acetyl number, infrared crystallinity index, and water of imbibition values. Benzylamine was found to be an intracrystalline swelling agent, while 4‐amino acetophenone brought about changes in the accessible regions only. Benzylamine has been regarded as substituted methylamine, and its swelling and decrystallizing action on cotton fibers has been explained on the basis of its ability to form specific hydrates with water. The intercrystalline swelling action of 4‐amino acetophenone resulted in further opening up of the accessible portions of the fiber. This was explained on the basis of its inability to form any specific complexes with methanol as well as its low basicity. The weak basic character of 4‐amino acetophenone was attributed to the substitution of deactivating and meta‐directing acetyl group in the para‐position to the amino group of aniline.
Introduction of polymers into fibrous structures by solution impregnation
Authors: Rigdahl M. , Westerlind B. , Hollmark H. , De Ruvo A.
Published: April 2003

Dry‐formed networks of cellulose fibers, produced with a laboratory device, have been impregnated with aqueous solutions of poly(vinyl alcohol) or solutions of poly(vinyl acetate) in acetone. In both cases, the strength and stiffness of the networks increase several times compared with the unmodified structure. When aqueous solutions are used, it appears that a minimum amount of poly(vinyl alcohol) is required (ca. 2 wt %) to increase the strength appreciably, but when poly(vinyl acetate) dissolved in acetone is used, as a binder, the strength improves even at the lowest level of polymer addition. For the systems studied here, the elongation at rupture increased with increasing polymer concentration. In most cases, the amount of polymer in the network structure was less than 10 wt %. Some results from impregnations using other polymeric systems, e.g., latices, are also reported.