bluuebunny/crossref_metadata_2025 huggingface dataset:
Grafting of poly(acrylic acid) onto polyethylene filament and its distribution
Authors: Kaji Kanako
Published: April 2003

Radiation‐induced simultaneous grafting of acrylic acid onto high density polyethylene filament is carried out with aqueous solution of acrylic acid in the absence and presence of ethylene dichloride. Distribution of grafted poly(acrylic acid) is studied by two methods. One is optical microscopic investigation of cross sections of dyed filament, and the other is electron probe microscopy of acrylic acid graft filament after conversion to calcium acrylate. Qualitative study with WAXS is also carried out. Grafting begins from the surface or periphery and proceeds, with sharp boundary, to the core. The reaction takes place only in the amorphous part of polyethylene. The percent graft in the grafted part is homogeneous and rather high from the beginning of the reaction; it is true that additional grafting to the already grafted part takes place, but it is not so noticeable.
Crosslinking of poly(ethylene glycol) with divalent metal salts of mono(hydroxyethyl) phthalate, anhydride, and bisepoxide
Authors: Matsuda Hideaki , Miyoshi Noriyuki
Published: April 2003

Poly(ethylene glycol)s (PEG) were crosslinked with divalent metal salts of mono(hydroxyethyl) phthalate, anhydride, and bisepoxide to give metal‐containing cured rubbers. As the anhydride, hexahydrophthalic anhydride was used, and bisphenol A diglycidyl ether was the bisepoxide used. As for the physical properties of the cured rubbers obtained, the rubbers containing Mg showed much better physical properties than those containing Ca. In addition, the rubbers with high hard block contents and high overall crosslinking densities exhibited high tensile strength and Shore A hardness, and so did the rubbers having a high degree of crystallinity of the PEG soft block. The occurrence of crystallization became easy as the soft block length became longer and the soft block content became higher, or as the crosslinking density of the hard block became lower. The PEG‐based rubbers showed much higher water absorption than the previously reported poly(propylene glycol)‐based rubbers, due to the much higher hydrophilicity of the PEG block. Resistance to chemical attack and stress–relaxation are also discussed.
Modification of epoxy polymer by plasticizing, blending, or reinforcing
Authors: Feldman D. , Blaga A. , Coriaty E.
Published: April 2003

Epoxy polymer (EP) was modified by incorporation of DBP, PVC, PVA, and glass fiber reinforcement. The morphology of the unmodified polymer and the various blends was studied by SEM, dispersive X‐ray analysis, and DSC. Results indicated that EP and DBP are miscible in the proportions used in this work (up to 10% of DBP). PVA added to cured EP in a concentration of 10% occurs as a separate phase. The morphology of EP–PVC blends is relatively complex: EP and PVC are immiscible at low concentration of the second component (up to 10% of PVC), but become mutually and increasingly more miscible as the concentration of PVC increases. Incorporation of DBP into EP causes a marked reduction in the heat distortion temperature (HDT), whereas addition of PVC has only a moderate effect. Modified EP containing small amounts of DBP (up to 4%) has moderately lower bond strength than the unmodified polymer, as evidenced by lower ultimate tensile strength of the adhesion sandwich specimens mounted on aluminum substrate. However, as the concentration of DBP in the blend increases, the ultimate tensile strength is slightly higher than that of the unmodified EP. Blending of EP with PVC, PVA, and glass fibers has generally a detrimental effect on the ultimate tensile strength. Outdoor exposure for 100 days (between January and April) generally caused deterioration of the tensile strength of all samples. EP‐based blends containing DBP, however, had better resistance to deterioration in outdoor exposure than the other blends, including unmodified EP.
On the use of the dimethyl terephthalate/dimethyl isophthalate recrystallization residue as a raw material in the production of solid polyurethane foams with reduced flammability
Authors: Troev K. , Todorov K. , Borisov G.
Published: April 2003

The residue from the recrystallization of the dimethyl terephthalate/dimethyl isophthalate fraction consists mainly of the dimethyl esters of the phthalic acids (ca. 82–85%) and about 15% aldehydes. It is shown that the isophthalic fraction affords the hydroxyl group containing phosphonates on treatment with diethyl phosphite in the presence of alkaline or peroxide catalysts. The residue treated in this manner can be used for preparing oligoester alcohols and solid polyurethane foams from them with reduced flammability.
Self‐diffusion of small molecules in cellulose gels using FT‐pulsed field gradient NMR
Authors: Brown Wyn , Stilbs Peter , Lindström Tom
Published: April 2003

Transport in cellulose gels has been studied with ethylene glycol and crown ether (15‐5) as “probes” using an NMR spin–echo technique. The cellulose content was varied in range 20–55% (w/w). The retardation of diffusion was found to be adequately described by simple first‐order expressions in concentration of cellulose.
Carboxyl‐containing polyesters and polyurethanes from dibenzyl L‐tartrate
Authors: Kuramoto Noriyuki , Sakamoto Munenori , Teshirogi Takuma , Komiyama Jiro , Iijima Toshiro
Published: April 2003

We have prepared polyesters from succinyl chloride, adipoly chloride, and telephthaloyl chloride with dibenzyl L‐tartrate, polyurethanes from hexamethylene diisocyanate, tolune 2,4‐diisocyanate, and methylene‐bis(4‐phenyl isocyanate) with dibenzyl L‐tartrate. The molecular weights of these polymers were generally low except for one of the polyurethanes. These polymers were reduced to give those having carboxyl side groups. Potency for inducing interferon was tested for one of the polymers. The result was not encouraging in showing low activity.
Upgrading the melt flow index to rheogram approach in the low shear rate region
Authors: Shenoy A. V. , Saini D. R.
Published: April 2003

The unified viscosity function curves proposed earlier by the authors have an inherent limitation in the low shear rate region. This limitation is the effect of using the melt flow index as a normalizing factor to obtain the coalesced curves, which itself is insensitive to molecular parameters such as molecular weight distribution. A single integral constitutive equation of the BKZ type is used to derive the viscosity function which would be useful in generating unified curves based on the melt flow index but devoid of the limitation of molecular weight distribution effects in the low shear rate region.
Crystallization of PP in PP/SEBS blends and its correlation with tensile properties
Authors: Gupta A. K. , Purwar S. N.
Published: April 2003

Crystallization of polypropylene (PP) in the blends of PP with styrene–ethylene butylene–styrene triblock copolymer (SEBS) is studied through differential thermal analysis (DTA) and X‐ray diffraction measurements. Analysis of crystallization exotherm peaks in terms of crystallization nucleation and growth rates, crystallite size distribution, and crystallinity revealed differences in the morphology of PP component in the blend in the different regions of blend composition. Crystallinity determined by X‐ray diffraction and DTA showed identical variations with blend composition. Variations in tensile properties of these blends with blend composition are also reported. Correlations of the various tensile properties with the crystallization parameters, viz., the crystallinity and crystallite size distribution, are presented, which confirm the influence of crystallization of PP component on the tensile properties of these blends.
Compatibility of poly(ϵ‐caprolactone) (PCL) and poly(styrene‐co‐acrylonitrile) (SAN) blends. I. Blends containing SAN with 24 wt% acrylonitrile
Authors: Chiu Shao‐Cheng , Smith T. G.
Published: April 2003

Polymer blends of poly(ϵ‐caprolactone) (PCL) and poly(styrene‐co‐acrylonitrile) (SAN), containing 24 wt % acrylonitrile (AN), were prepared, and their transition behavior was examined by thermal analysis and dynamic mechanical testing. The blends were judged to be compatible on the basis of the presence of a single, compositionally dependent glass transition. The results of thermal treatment upon blends glass transition behavior and the dependence of thermal history upon the crystallization of semicrystalline PCL were also studied. The crystallization of PCL from SAN/PCL blends was found to be retarded by the presence of SAN, and crystalline PCL was found to exist only in blends containing a high PCL concentration. Blends which do not contain crystalline PCL were transparent, and their glass transition behavior can be correlated by the Gordon–Taylor equation. Phase separation, which was characterized by lower critical solution temperature (LCST) behavior, was found to occur when blends were heated to elevated temperatures.
Method for studying orientation variations near surfaces in semicrystalline polymers
Authors: Buckley C. P. , Taylor R. J.
Published: April 2003

The method of grazing incidence X‐ray diffraction provides a convenient means of examining crystal orientation close to the surface of a semicrystalline polymer. Since the sampled depth is governed by the choice of X‐radiation (via its absorption coefficient) and the angle of incidence, it is under the control of the experimenter. The method was tested and shown to be valid by applying it to a crossply laminated film of oriented polyethylene, of thickness 50 μm, in which the different crystal orientations on opposite faces of the film were known. Further experiments, with two polyethylene films of 20 μm and 40 μm thickness each extruded with differing rates of cooling on each surface, demonstrated the ability of the method to resolve spatial variations of orientation on this scale arising during manufacture.
Studies on the improvement of cured two‐stage phenolics performance. III. Relation between conditions of heat treatment and properties of wood‐flour‐filled phenolics
Authors: Fukuda Akinori , Hasegawa Kiichi , Horiuchi Hikaru
Published: April 2003

The effect of heat treatment on the properties of cured two‐stage phenolics was studied. Samples were compression‐molded from the compound that was prepared from novolac, wood flour (100 phr), and hexamethylenetetramine (15 phr). Samples were heat‐treated in conditions of four levels for temperature (150°C, 170°C, 190°C, and 210°C) and time (4, 8, 16, and 24 h). The properties of samples heat‐treated, such as weight loss, dimensional stability, water absorption after boiling, and flexural properties were measured. The relation between the properties and the conditions of heat treatment was examined statistically. From the results, it was decided that the optimum conditions of heat treatment for practical use were: (i) to decrease water absorption and to heighten electrical resistance, 210°C, 24 h; (ii) to improve flexural properties at room temperature and at 160°C; 170°C, 8 h, and 170–190°C, 24 h, respectively. It was concluded that the decrease of water absorption of moldings was due to the increase of hydrophobic nature of wood flour included in moldings by heat treatment and that the improvement of flexural property of moldings at 160°C was due to an increase of crosslinking density by heat treatment. The reasons for the improvement of the electrical properties by heat treatment were also discussed.
Use of a microcomputer with a gas permeation apparatus
Authors: Toi Keio , Ito Tomoyasu , Shirakawa Toshiaki , Ichimura Hajime , Ikemoto Isao
Published: April 2003

Hardware and software for collecting and storing the data of gas permeation in polymer membranes from the vacuum detector and various sensors have been developed for the GP‐IB microcomputer online system. The system uses BASIC language programs. In comparison to manual inputs and calculations, the programs allow reductions in the time required for data treatment and in the standard deviation for a determination and, moreover, an improvement in the reproducibility of the results.
Dielectric and ultrasonic absorption in some linear polyamides
Authors: Aziz A. W. , Abd‐El‐Nour K. N.
Published: April 2003

The dielectric behavior of some linear polyamides has been studied over a frequency range from 102 to 105 Hz between 20°C and 90°C. Also the change in attenuation of longitudinal ultrasonic waves has been measured as a function of frequency and temperature. Analysis of the results shows α‐ and β‐ relaxations. The movement of amide protons involved in intermolecular hydrogen bonds is also noticed.
Structure property studies of polyester‐ and polyether‐based MDI–BD segmented polyurethanes: Effect of one‐ vs. two‐stage polymerization conditions
Authors: Abouzahr Saad , Wilkes Garth L.
Published: April 2003

The effect of the polymerization method (one‐or two‐stage) on the morphology and properties of specific polyether‐ and polyester‐based urethanes was studied. For the systems investigated, the polymerization technique was somewhat more influential on properties when the soft segment was a polyester than when it was a polyether. In the case of the polyester, a one‐stage process yields materials with somewhat poorer physical properties than for a two‐stage technique. This decrease in properties is attributed to a higher soft–hard segment interaction and to the higher mutual solubility of the segments that is brought about by a possible broader molecular weight distribution of hard segments produced in a one‐stage reaction. A large difference in hard segment length distribution, however, was not expected since the MDI isocyanate moieties should display equal reactivity. In the case of polyether soft segments, any effect of the polymerization method appears to be largely offset by the higher incompatibility of the hard and soft components.
Photoinduced tension of polymers
Authors: Maerov S. B. , Avakian P. , Matheson R. R.
Published: April 2003

Photoirradiation of polymer films at constant length induced a fast tension reduction (time scale: seconds) followed by slow tension buildup (time scale: minutes). Immediately after irradiation, fast tension buildup was followed by slow tension decay. Cycles were repeatable without significant hysteresis loss. The amplitude of both phenomena are intensity‐dependent in the ultraviolet–visible spectral regions; both phenomena are thermal rather than photochemical effects. Light‐absorbing chromophores in the polymer structure, or in additives such as dyes, lead to absorption of light and internal conversion into heat. The classical, rapid thermal expansion (or contraction) on heating (or cooling) leads to the fast relaxation (or buildup) of tension. The elastic, entropic response of the sample with its longer relasation time leads to slow buildup (or decay) of tension. Fast and slow responses are observed sequentially with film of extensively crosslinked Riston photopolymer resist or with Kapton polymide film, whereas, in experiments with latex rubber, the rubbery behavior dominates.
Dielectric and dynamic mechanical measurements of poly(4‐methyl pentene‐1)
Authors: Lee Gilbert F. , Hiltz Thomas
Published: April 2003

The α‐relaxation process of poly(4‐methyl pentene‐1) was studied by dielectric and dynamic mechanical means. The complex dielectric constant was determined at nine discrete frequencies from 100 to 10,000 Hz and over a temperature range of −50–90°C. The complex dynamic mechanical Young's modulus was determined over the audiofrequency range of 10–22,000 Hz and a temperature range of 21–76°C, from which a master curve was constructed. The relaxation process was studied by comparing the activation energies and width of the dispersion curves. The results of a logarithmic frequency vs. reciprocal temperature plot of the loss peak maxima show that both the dielectric and mechanical curves are roughly linear but have different slopes. From the slopes the activation energies were determined. For the dielectric data an activation energy of 39 kcal/mol was obtained, whereas for the mechanical data a value of 106 kcal/mol was found. The width of the dispersion curves was determined by using a Cole–Cole empirical fit. The width of the dielectric dispersion curve is narrower by as much as a factor of 3 than the mechanical dispersion curve. It is concluded that the energy to cause the large scale molecular motion involved in the α‐relaxation is lower when excited by an alternating electric field than by an alternating stress field. Also the number of repeat units involved is smaller in the dielectric case than in the mechanical case.
Characterization of some poly(methyl methacrylate) prepared by emulsion polymerization in presence of egyptian delta titano magnetite ore (EDTMO)
Authors: Moustafa A. B. , Sayyah S. M. , Badran A. S. , Hassanin M. S.
Published: April 2003

The emulsion polymerization of methyl methacrylate was studied in water using potassium persulphate as initiator and dedocyl–benzene sodium sulphonate as emulsifying agent at 85°C. The effect of Egyptian delta titano magnetite ore (EDTMO) upon the activation energy and on the mean average molecular weights of the obtained polymers was studied. It was found that the viscosity average molecular weights increase with decrease of reaction temperature and initiator concentration but increase with increase of monomer concentration in the reaction medium. Some of the polymer samples prepared in absence and in presence of some (EDTMO) were separated on tlc plates according to molecular weight in binary mixture, benzene:methanol (1:1.4 by volume) at 30°C. The tlc techniques were performed to give an idea about the molecular weight distribution of the polymer samples obtained.
Complexation of samarium ion with poly(acrylic acid) grafted onto polyethylene by radiation‐induced method
Authors: Maekawa Toshihiko , Nishide Hiroyuki , Tsuchida Eishun , Ohmichi Hideki , Okamoto Jiro
Published: April 2003

Acrylic acid was graft‐polymerized onto polyethylene powder by preirradiation method. The grafted powder (PE‐g‐AA) rapidaly adsorbed Sm3− ion in high efficiency. The poly(acrylic acid) grafted to the surface region of PE acted as an effective chelating site for the relatively large Sm ion. The complex formation constant of Sm ion with PE‐g‐AA was much larger than those of Sm ion with poly(acrylic acid) and propionic acid and of Cu2+ ion with PE‐g‐AA.
Depolymerization of nylon 6: Some kinetic modeling aspects
Authors: Ogale Amod A.
Published: April 2003

Depolymerization reactions of nylon 6 [poly(ϵ‐caprolactam)] have been modeled based on an existing mechanism for reversible polymerization reactions. The method of moments proposed by Min has been used together with kinetic and equilibrium constants for polymerization reactions to simulate depolymerization reactions. Simulation results thus obtained for batch and semibatch processes compare well with the corresponding experimental results.
Interactions between dyes and polyelectrolytes: Effect of polymer–polymer interactions
Authors: Petrak K.
Published: April 2003

The competition between methyl orange dye and various polymers [gelatin, poly(vinyl alcohol), polyacrylamide, etc.] for the binding sites on quaternized poly(1‐vinylimidazole) in aqueous solutions was studied. The method used was based on a well‐known effect of dissolved polyelectrolytes on the rate of diffusion of solutes through semipermeable membranes. The final results are expressed as the ratio of C1″(bound)/C1′(bound), where C1″(bound) is the amount of the solute adsorbed to a mixture of two polymers and C1(bound) is the amount of solute bound to a single polymer. In the case of quaternized poly(1‐vinylimidazole) it was found that as much as 15% of the solute bound to the polymer can be replaced by another, “nonadsorbing” polymer.
An analysis of CSTRs in series for solution copolymerization
Authors: Rodriguez F.
Published: April 2003

Continuous copolymerization is used in order to achieve a product of uniform composition. However, it is difficult to attain high conversions without resorting to very high residence times in a single tank. The way to avoid this is to use a series of stirred reactors with addition of one comonomer and initiator to each one after the first. The allowable half‐life of the initator is a function of the residence time. When all the reactors are equal in volume so that the residence time is the same in each, it can be shown that the incremental conversion in each successive reactor must decrease in a well‐ordered manner. As a specific example, a copolymerization is postulated with total polymer concentration restricted to the region where viscosity is manageable with conventional mixing equipment. Under these conditions the relative reactivity ratios are presumed to be constant and temperature can be held within narrow bounds.
Photolysis of poly(3‐buten‐2‐one), poly(4,4‐dimethyl‐1‐penten‐3‐one), and poly(3‐methyl‐3‐buten‐2‐one) in the presence of oxygen
Authors: Naito Ikuo , Teshima Kazuhiro , Sato Noboru , Sekito Hirofumi , Kinoshita Akihiro
Published: April 2003

Photolysis of poly(3‐buten‐2‐one) (PMVK), poly(4,4‐dimethyl‐1‐penten‐3‐one) (PBVK), and poly(3‐methyl‐3‐buten‐2‐one) (PMIK) were carried out in dioxane under oxygen or nitrogen bubbling. The main chain degradations of PBVK and PMIK were quenched and polymeric peroxides were produced. The heat treatment of the polymer irradiated in the presence of oxygen promoted the degradation. The photodegradation of PMVK was enhanced in the presence of oxygen.
Relationship between electron sensitivity and chemical structures of polymers as EB resists. III. Electron sensitivity of various polyamides using 3‐amino perhydroazepine
Authors: Oguchi Kiyoshi , Sanui Kohei , Ogata Naoya , Takahashi Yoichi , Nakada Tomihiro
Published: April 2003

Homopolyamides and copolyamides containing a variety of reactive and/or stabilizing groups, such as double bonds, epoxy groups, or naphthalene moieties, were synthesized using 3‐amino perhydroazepine (APA) as a diamine monomer. These polymers were evaluated as electron beam (EB) resists, in order to investigate the relationship between EB sensitivity and chemical structure of the polyamides. It was found that polyamides containing double bonds were easily crosslinked by the EB exposure and that the sensitivity of a polyamide containing double bonds in the side chain was higher than that of a polyamide containing double bonds in the main chain. The sensitivity of a polyamide containing epoxy groups was lower than that of the above. Copolymer from APA, 77 mol % of trans‐3‐hexenedioyl chloride (HC) and 23 mol % of 2,6‐naphthalenedioyl chloride (NC) had the same EB sensitivity as that of the homopolymer from APA and HC. The polyamides had excellent dry etching durability and were adaptable to EB lithography.
Thermal and structural properties of tri‐O‐substituted cellulose ethers
Authors: Isogai Akira , Ishizu Atsushi , Nakano Junzo
Published: April 2003

Tri‐O‐substituted cellulose ethers prepared by the use of SO2–diethylamine (DEA)–dimethylsulfoxide (DMSO) and powdered sodium hydroxide were characterized by measurement of melting points and degradation points and by differential scanning calorimetric (DSC) and X‐ray analyses. Their thermal and structural characteristics were ascertained to be dependent on the kinds of substituents. Among the ethers examined, four kinds of arylmethylcelluloses showed the characteristics of thermotropic liquid crystals (smectic). Tri‐O‐α‐naphthylmethyl‐cellulose showed the three transformations due to a solid–smectic phase, a smectic–nematic phase, and a nematic–isotropic phase transformation. This thermotropic liquid crystal was enantiotropic below 200°C.
Polymeric reaction of acrylic polymer–monomer system irradiated by low energy electron beam. I. Effects of molecular weight of polymer and polymer‐to‐monomer ratio
Authors: Takiguchi Ryohei , Uryu Toshiyuki
Published: April 2003

Polymeric reaction of the poly(n‐butyl acrylate) (PBA)–benzyl acrylate (BzA) system induced by a low‐energy electron beam was investigated. In order to elucidate the reaction behavior of the PBA–BzA system, the gel fraction, molecular weight of soluble part, and molecular weight distributions were examined by means of gel permeation chromatography (GPC) equipped with both ultraviolet (UV) and refractive index (RI) detectors. RI‐detected GPC curves represented the molecular weights and their distributions of the total polymers, graft polymer, homopolymer, and unreacted PBA, while UV‐detected curves only corresponded to the benzyl groups of graft polymer and homopolymer. Thus, the reaction behavior of the system was able to be followed by GPC. The molecular weight of the added PBA and the mole ratio of PBA/BzA were varied. The crosslinking, the graft reaction and the homopolymerization of BzA proceeded competitively during the polymeric reaction. The proportions of BzA unit incorporated into the crosslinked, graft and homo polymers were estimated by combining of measurement of gel fraction, UV‐detected GPC curves, and infrared (IR) spectrum of gel. It was revealed that in the system containing PBA with high molecular weight, the grafting, and the crosslinking reactions predominated. The main reaction was the grafting in the system with a high mole ratio of PBA/BzA, while it was the homopolymerization in the systems with the low mole ratio of PBA/BzA. The reaction mechanism is discussed on the basis of reactivity and mobility of polymer radicals.
Crystalline‐state extrusion of low density polyethylenes
Authors: Benelhadjsaid Chadli , Porter Roger S.
Published: April 2003

Three low density polyethylenes, one long branched (A) and two linear (B and C), have been solid‐state‐extruded at several constant temperatures from ambient to 80°C and to draw ratios ⩽ 8. The initial densities and melt indices of A, B, and C are 0.920, 0.920, and 0.935 g/cm3, and 1.9, 0.8, and 1.2, respectively. Melt‐crystallized cylindrical billets were extruded through conical dies in an Instron Capillary Rheometer. The linear polymers were found to draw by extrusion more readily than the branched; all three strain‐harden. Density, birefringence, tensile, and thermal properties have been evaluated as functions of extrusion temperature and draw ratio. Despite a measured loss via die swell, substantial orientation takes place during solid‐state extrusion as evidenced by increases in transparency, birefringence, and tensile modulus (up to 4.5 times that of the original isotropic polymer). Depending on the polymer and the draw temperature, density does go through a minimum or shows a monotonic increase with draw by extrusion. A minimum in modulus is also observed at low draw and at all draw temperatures for all three polymers. The highest tensile moduli achieved are 0.73, 0.46, and 1.5 GPa for A, B, and C, respectively, at their highest draw ratio. The melting point for polymer B decreases with extrusion draw ratio, whereas it remains constant after a small initial drop, for the two others. For all three low density polyethylenes, birefringence increases rapidly with extrusion draw and then levels off at high draw. The birefringence limit is similar for A and B, i.e., 0.046 ± 0.004, but higher for C, i.e., 0.068 ± 0.009. This work extends beyond others in that it studies the effect of short as well as long branches in solid‐state extrusion by comparing the linear and long branched LDPE polymers and LDPE with prior evaluations of HDPE.
Porous bead aliphatic–aromatic methacrylate copolymers III. The effect of diluent on porous structure formation of MMA–DMN copolymers
Authors: Wójcik Anna B.
Published: April 2003

Porous bead copolymers of di(methacryloyloxymethyl)naphthalene and methyl methacrylate have been synthesized using a mixture of isooctane and toluene as a diluent of the monomer system. The copolymers obtained exhibit similar specific surface areas and enhanced specific pore volume as compared to those prepared in the presence of dodecane and toluene. Their submicroscopic structure is visualized as first‐order organization of microglobules similarly to PPS‐type styrene–divinylbenzene copolymers.
Electrically conducting polymers from conjugated bis‐phthalonitrile monomers
Authors: Walton Theodore R. , Griffith James R. , Reardon Joseph P.
Published: April 2003

Elelectrically conducting polymers have been synthesized from completely conjugated bisphthalonitrile monomers. The monomers melt and are thermally polymerized at 260–300°C in air and then are converted into conductive materials by further processing at elevated temperatures in an inert atmosphere. Because the monomers remain in a liquid stage for 1–2 h, depending on the cure conditions, moldings, castings, and pre‐pregs can be fabricated using conventional processing techniques. The conductivity can be varied from that of an insulator to approximately 10+2(Ωh cm)−1. For example, after a 600°C treatment, the conductivity is approximately 1(Ω cm)−1. Since reactive dopants are not used, the material and conductivity are stable in ambient as well as more aggressive environments, allowing them to function at 300°C and above. The monomers are well characterized, but the structure of the cured and postcured polymers are not yet well defined because of their high stability and intractability in the cured state.
On the effects of very low levels of long chain branching on rheological behavior in polyethylene
Authors: Bersted B. H.
Published: April 2003

A comparison is made of the effects of very low levels of long chain branching (less than 0.1 branch per 1000 CH2) on the rheological behavior of polyethylene for samples, in which the branching has been introduced by means of peroxide decomposition or thermal‐mechanical degradation. Both the activation energy and viscosity at low rates are shown to increase considerably more rapidly with branching level for samples containing branching formed from peroxide decomposition than for samples containing branching formed as a result of thermal or mechanical degradation. A model, which is based on parameters obtained for highly branched low density polyethylene and experimental molecular structure measurements, is shown to adequately account for the flow curves of samples containing branching introduced by thermal or mechanical degradation. Poor agreement of the model with experimental flow curves for peroxide branched samples is obtained, presumably because of the inability of the low density polyethylene parameters to adequately describe the flow properties of these samples, which are thought to contain tetrafunctional branch points. The good agreement between theoretical models, predicting relationships between activation energy and branching level, and experimental data is taken as lending further credence to the idea that the large variations seen in the rheological behavior with branching concentration at low branching levels are due to changes in the relative proportion of discrete branched and linear species with branching level. In accord with experimental results, a maximum in low rate viscosity with branching level is predicted. The maximum is predicted at approximately 0.25 branches/1000 CH2.
Effect of stirring on cellulose graft copolymerization. V. Influence of reaction parameters
Authors: Graczyk Tomasz , Hornof Vladimir
Published: April 2003

Styrene was grafted onto dissolving pulp by the cellulose xanthate–Fe2+–H2O2 system. Reaction parameters were found to have strong influence on conversion to both copolymer and total polymer, as well as on the dependence of polymerization on stirring. The formation of polymer was almost completely inhibited by pure oxygen, while air only slowed down the reaction. Under inert atmosphere, the effect of agitator speed was found to be strongly dependent on monomer and substrate concentration as well as on the concentration of emulsifier. The location of the maximum on the conversion vs. agitator speed curve was strongly affected by the shape of the stirrer. The presence of emulsifier had a relatively small effect on copolymer formation in the case of acrylamide, a water‐soluble monomer. Also the effect of stirring was less marked in the case of acrylamide. In all the systems investigated, the conversion to copolymer and total polymer was found to drop rapidly above a certain limiting agitator speed. The latter was different and characteristic for each system. No polymer formation was observed beyond 1000 rpm regardless of all other reaction conditions.
A rheological study of laminar–turbulent transition in drag reducing polymeric solutions
Authors: Tandon P. N. , Kulshreshtha A. K.
Published: April 2003

Presented herein are the studies of laminar–turbulent transition in micropolar and power law fluids flowing in a circular pipe. For some parametric values of micropolar and power law fluids, both depict the drag reducing properties. The parametric values of these representations have been obtained from the experimental results of Mc‐Comb. It has been observed that, in both the cases, as the drag‐reducing property in the solution increases, the first transition point moves towards the walls of the pipe. It is also observed that the onset of early turbulence phenomenon occurs for the drag‐reducing polymeric solutions.
Characterization of acidic groups in oxycelluloses III. Effect of cation freeing and blocking on estimation of carboxyl groups and lactones by the idometric method
Authors: Achwal W. B. , Murali Radha
Published: April 2003

A differentiation between free carboxyl and various lactone groups in different types of oxycelluloses was carried out based on the variation in their reaction rate with KI/KIO3 solution. For oxycelluloses prepared under acidic conditions, a large proportion of carboxyl groups are present in free form. Each oxycellulose was also studied after cation freeing as well as after blocking the free carboxyl groups by treatment with sodium chloride.

Cation freeing was found to cause considerable lactonization of carboxyl groups; sodium chloride treatment blocked them only partially.
Pyrolyzed, conducting kapton polyimide: An electrically conducting material
Authors: Hu C. Z. , Andrade J. D.
Published: April 2003

Polyimide was pyrolyzed in an argon atmosphere at 900°C for 1h. The room temperature conductivity of the polyimide gradually increased from 15 to 100 S/cm with increased pyrolysis time. Further increase in the pyrolysis time did not increase the conductivity. X‐ray photo‐electron spectroscopy (XPS) showed that the polyimide changed from pure insulator to conductor; detailed XPS spectra of carbon, nitrogen, and oxygen 1s bands showed no further elemental decomposition of the polyimide at 900°C. The high temperature treatment results in internal rearrangement to form a large, dense heterocyclic network. The film probably consists of tiny conductive particles dispersed in an amorphous carbon matrix. The polyimide is placed between two quartz plates during pyrolysis; the resulting film is flat, has uniform conductivity, is nonbrittle, has high chemical resistance, and shows better mechanical strength than films pyrolyzed in free‐standing conditions.
Miscibility of polyethyloxazoline with thermoplastic polymers
Authors: Keskkula H. , Paul D. R.
Published: April 2003

Polyethyloxazoline (PEOx) blends with several other thermoplastic polymers were examined by differential scanning calorimetry (DSC) for miscibility. Styrene/acrylonitrile (SAN) copolymers having compositions in the range of about 20–40% acrylonitrile (AN) by weight were found to be miscible with PEOx whereas SANs outside this range were not. The polyhydroxyl ether of bisphenol A (Phenoxy) was also found to be miscible with PEOx. A vinylidene chloride copolymer (Saran) was found to be partially miscible with PEOx, whereas poly(methyl methacrylate) and polycarbonate were not miscible at all.
Thermodynamics of the process of adsorption of aliphatic amidpolyamine on cellulose
Authors: Nedelcheva Margarita , Mladenova Stefka , Valcheva Eva
Published: April 2003

The subject of this research is the thermodynamics of the adsorption equilibrium of three types of bleached pulp in water solutions of aliphatic amidpolyamine—Lamid‐1, (L‐1) in concentrations from 0.03 to 0.50 g/L in a temperature interval of 0–60°C and the influence of pH of the environment on the adsorption process. It was established that with the increase of temperature the quantity of adsorbed L‐1 decreases. The values of the heat of adsorption are negative, do not depend on the quantity of adsorbed L‐1, and are of the order 111.7–14.7 kJ/mol. The values of the entropy of the entropy of adsorption are also negative and are of the order of 76.8 ÷ 84.5 J/mol•K. Adsorption equilibrium is described by ther adsorption isotherm of Langmuir. Optimum pH for lower concentrations of the solution is from 5 to 7. When the concentrations of the solution are higher (C ≧ 0.15 g/L) the process can also take place very satisfactorily in an alkaline environment.
Analysis of mass transfer effects in ethyl cellulose manufacture
Authors: Chakrabarti A. , Jaganathan R. , Chaudhari R. V.
Published: April 2003

A theoretical analysis of mass transfer effects in ethyl cellulose manufacture has been reported. This is the first model to describe a complex fluid–solid reaction in the presence of two immiscible liquids. The model derived here can be used to evaluate the dependency of the overall rate on different parameters incorporating the multiphase mass transfer effects.
A study on the polycondensation of bis‐hydroxyethyl terephthalate
Authors: Lin Chen‐Chong , Baliga Satish
Published: April 2003

Poly(ethylene terephthalate) (PET) was synthesized from its monomer bis‐hydroxyethyl terephthalate (BHET), in the presence of Sb2O3 catalyst. A second order irreversible reaction model was developed, and the apparent rate constant was evaluated by observing the course of intrinsic viscosity change. At 278°C, the apparent rate constant in the presence of 0.025% (by weight) of Sb2O3 was found to be 0.945 L/mol h.
Influence of chalk and its surface treatment on crystallization of filled polypropylene
Authors: Kowalewski T. , Galeski A.
Published: April 2003

Isotactic polypropylene has been shown to crystallize from the melt spherulitically at intermediate undercoolings (100–130°C) in the presence of a high amount (40 wt %) of chalk (calcium carbonate). Linear growth rate is not remarkably affected by the presence of a filler. Both nonisothermal and isothermal crystallization DSC experiments indicate that chalk acts as a weak nucleant. Introduction of liquid [oligomer of ethylene oxide (OEO), Mw = 300] at polymer–filler interface lowers the nucleating activity of chalk. Analysis of crystallization kinetics in Avrami coordinates, followed by dimensional‐analysis correction for the case of nonintegral values of exponents, indicates that the amount of extra “chalk nuclei” is approximately constant in the range of 100–130°C while the amount of OEO‐modified “chalk nuclei” decreases with the increase of the crystallization temperature. Comparison of the melting endotherms indicates that filled melt‐crystallized material contains higher fraction of lower melting crystallites than unfilled polypropylene. This fraction is also higher in the case of polypropylene filled with unmodified chalk. Nucleating activity of chalk has been shown to depend upon its crystal structure (calcite or aragonite), surface topography, and aggregation.
Synthesis and characterization of some aromatic polyphosphonates
Authors: Natansohn Almeria
Published: April 2003

Novel aromatic polyphosphonates are synthesized by polycondensation of chloromethyl (methyl, phenyl) phosphonic dichloride with bisphenols using three procedures: melt, solution, and phase transfer catalysis. The molecular weights and spectral characteristics are presented. Mixtures of the polyphosphonates with polyacrylonitrile and nylon 66 are compatible only when the chloromethyl group is present. Eight percent of polyphosphonate in the mixture confers flame resistance to the polymers.
High‐speed reverse‐phase liquid chromatography with 3 μm packing for analysis of fiber‐reinforced epoxy composite formulations
Authors: Noël D. , Cole K. C. , Hechler J.‐J. , Chouliotis A. , Overbury K. C.
Published: April 2003

A high‐speed reverse‐phase liquid chromatography column packed with 3 μm particles has been used to separate different epoxy resin formulations used in manufacturing fiber‐reinforced composites. The mass transfer of the solute between the stationary phase and the mobile phase is improved with the decrease of the particle diameter, and the height equivalent to a theoretical plate remains low even at higher flow rates of eluent. The separation of a typical epoxy resin was achieved with good resolution in less than 6 min on a short column 4 cm long packed with 3 μm particles, as compared to about 30 min on a 30 cm long column packed with 5 μm particles. Moreover, the regeneration time with gradient elution is considerably reduced with a short column. Separations of different formulations are shown and the advantages and disadvantages of these 3 μm packings for a quality control laboratory are discussed. In addition, the ageing of Narmco Rigidite 5208/WC3000 prepreg at room temperature in a controlled atmosphere has been quantified using these high‐speed columns.
Crosslinking of amidated polybutadiene with resole. I
Authors: Hara Hajime , Araki Yoshihiko , Orii Shingo
Published: April 2003

Various liquid polybutadiene derivatives were examined as modifiers to improve the brittleness of phenolic resins. Amidated polybutadienes obtained from a maleinated polybutadiene and ammonia had the highest curing tendency when they were reacted with resole under mild conditions. The cured resins were homogeneous and the brittleness of the phenolic resins was remarkably improved. Crosslinking efficiency was closely related to the succinamic acid group of the amidated polybutadiene. Thermal behavior of the succinamic acid group was also related to the effects of curing temperature and curing time on crosslinking. From these observations, cross‐condensation between the succinamic acid group of an amidated polybutadiene and resole seemed to have occurred to a great extent than the self‐condensation of resole itself and oxidative crosslinking of the amidated polybutadiene.
Kinetics of transesterification of dimethyl terephthalate with 1,4‐butanediol catalyzed by tetrabutyl titanate
Authors: Hsu J. , Choi K. Y.
Published: April 2003

The kinetics of tetrabutyl titanate catalyzed transesterification of dimethyl terephthalate (DMT) with 1,4‐butanediol (BD) is investigated. Detailed analysis of experimental data indicates that equal reactivity hypothesis for functional groups is valid for [BD]/[DMT] molar ratios greater than 2 up to 75% conversion. Effects of reaction temperature and catalyst concentration are also discussed.
Cinnamylidene‐amine‐sensitized photodegradation of polyethylene
Authors: Czekaj Tadeusz
Published: April 2003

The activity of Schiff's bases of cinnamic aldehyde and aromatic amines in the controlled photodegradation of polyethylene (PE) was studied. N‐cinnamylidene anilines containing different substituents in the amine ring (methyl group, halogen, or amine group) and N‐cinnamylidene α‐naphthyl amine were synthesized and introduced into the polyethylene films by compression molding or extrusion, and they were exposed to the filtered ultraviolet light produced by mercury lamp. The changes in molecular weight, tensile strength, and characteristic IR absorptions were followed during irradiation to control the processes undergoing in the polymer films. It was discovered that N‐cinnamylidene anilines containing methyl or halogen substituents and N‐cinnamylidene α‐naphthyl amine accelerated the photodegradation of polyethylene. Their sensitizing activity increased when the mixtures of Schiff's bases and stannous laurate were introduced into the polymer. PE films containing these additives became brittle after 600 h exposure to the artificial UV light which was the equivalent of 1.5–2 years exposure to the natural sunlight in the medium geographic latitudes. The mechanism of the initial step of photodegradation is discussed.
Miscible blends of poly(styrene‐co‐acrylonitrile) and poly(α‐methyl styrene‐co‐acrylonitrile) with hydroxyl‐containing polymethacrylates
Authors: Goh S. H. , Siow K. S.
Published: April 2003

Poly(styrene‐co‐acrylonitrile)(SAN) and poly(α‐methyl styrene‐co‐acrylonitrile)(MSAN) are miscible with poly(2‐hydroxyethyl methacrylate) (PHEMA) and with poly(2‐hydroxypropyl methacrylate) (PHPMA). That SAN and MSAN are immiscible with poly(n‐propyl methacrylate) and with poly(isopropyl methacrylate) but miscible with PHPMA indicates the enhancement of polymer miscibility due to hydroxyl groups. The miscibility of these blends is explained in terms of recent theories for copolymer/homopolymer blends.
Alkalization mechanism of cellulose in hydroxypropylcellulose preparation process
Authors: Yokota H.
Published: April 2003

The role of alkali treatment of cellulose in hydroxypropylcelluloe (HPC) preparation has been studied from the viewpoint of the selective distribution of sodium hydroxide between HPC and cellulose phases. Generally it is considered to be important to prepare uniform alkali cellulose, whose calculated value of composition is C6H10O5NaOH. x H2O, prior to etherification of cellulose. Therefore, enough alkali to obtain alkali cellulose is used by major manufacturers of cellulose ethers. However, HPC having good solution qualities and performance properties can be prepared even from partially alkalized cellulose by using 0.2–0.4 molar sodium hydroxide per anhydroglucose unit. The results obtained from a series of experiments indicate the following mechanism for the formation of HPC. Hydroxypropylation is initiated in the alkalized portion of cellulose if such portion and propylene oxide are present together. As the hydroxypropylation proceeds, the liberated sodium hydroxide in HPC phase migrates into the cellulose phase due to the shift of distribution equilibrium of sodium hydroxide; the above tendency is enhanced by byproducts such as propyleneglycol. Some newly alkalized portions are present and hydroxypropylation follows. These processes are repeated, and then all portions of cellulose are alkalized and hydroxypropylated.
Poly‐1‐hexene, synthesis and solubility in dense carbon dioxide
Authors: Dandge D. K. , Heller J. P. , Wilson K. V.
Published: April 2003

Several poly‐1‐hexene samples were prepared using different Ziegler‐Natta catalysts, and their solubilities in dense carbon dioxide (CO2) were studied. Despite the varied molecular weight distributions (MWD) in the polymers, a surprising correlation was found between intrinsic viscosity and dense CO2 solubility. Due to the ability of dense CO2 to extract low‐molecular weight fractions preferentially, it is recommended that narrow MWD polymers be used, as far as possible, for dense CO2 solubility determinations.
Removal of polyethylene glycol mono‐p‐nonylphenyl ether and dodecylbenzenesulfonate by chloromethylated polystyrene–polyethylenepolyamines and –polyethyleneimines
Authors: Tashiro Tatsuo
Published: April 2003

The reactions of chloromethylated divinylbenzene crosslinked polystyrene (CMPS) with polyethylenepolyamines (PEPA), polyethyleneimines (PEI), 2‐methyl‐2‐oxazoline (MeOZO), and the hydrolysis of CMPS–MeOZO reaction products were carried out. The abilities of these products for removing a nonionic surfactant, polyethylene glycol mono‐p‐nonylphenyl ether (NP, n = 10), solutes in water were investigated. Removal rates of NP by and the amounts of NP removed by CMPS–PEPA, –PEI, –MeOZO, and hydrolyzate of CMPS–MeOZO were compared. The adaptability of removal behavior of the products to the Freundlich's adsorption isotherm and the amounts of NP removed by unit masses of the products were investigated. The products also removed an anionic surfactant, sodium dodecylbenzene sulfonate (DBS), solutes in water. The mechanisms for removing NP and DBS were discussed.