bluuebunny/crossref_metadata_2025 huggingface dataset:
Cyanoacetamide accelerators for the epoxide/isocyanate reaction
Authors: Eldin Sameer H. , Renner Alfred
Published: April 2003

The cyanoacetamides NCCH2CONHR1N (R2) (R3) are a new family of accelerators for the epoxy/isocyanate (EP/IC) reaction. Results obtained from systematic structure variations indicate that they belong to the “deactivated tertiary amine” type of catalyst with the cyanoacetamide group as the deactivating moiety. Reactivity can be controlled via the R1 substituent (cyanoacetamide) and/or by R2/R3. A reaction mechanism is proposed. The results of a factorial design experiment and IR determination of the oxazolidinone (OX)/isocyanurate (ICR) extinction maxima ratios were used to develope an optimized EP/IC system. A trial formulation (filled) is given in which rapid gelation, a high Tg value, and excellent mechanical properties were achieved with an accelerator concentration of less than 0.2%.
The electrical and physical properties of CuS– and CdS–polyacrylonitrile composite films prepared by using the organosol method
Authors: Im Sung Soon , Im Hee Suk , Kang Eun Young
Published: April 2003

Electrical and physical properties of the CuS‐ and CdS‐introduced polyacrylonitrile (PAN) films were studied. Electrically conducting PAN film was prepared by introducing CuS and CdS by the organosol method. Electrical surface conductivity of CuS‐ and CdS—PAN composite film prepared by the organosol method was 10−1 and 10−5 S/cm, respectively. Temperature dependence of surface conductivity for CuS—PAN composite film was investigated. The IV characteristics and time dependence of conductivity of samples were observed. The conduction mechanism of CuS– and CdS–PAN composite film was mainly electronic. Electrical properties of the CuS– and CdS—PAN composite film were mainly governed by the CuS and CdS crvstal formed in the PAN film. Temperature dependence of surface conductivity of the heat‐treated CuS—PAN composite film was also investigated. Results show that the electrical properties of the sample were varied slightly according to annealing temperature. Tensile strength and modulus of CuS– and CdS—PAN composite film were slightly decreased than original PAN film, but this decrease was not prevented utilization in electronic devices.
Evaluation of alkylated diphenyl ether disulfonate surfactants in 60 : 40 styrene—butadiene emulsion copolymerization
Authors: Vanderhoff J. W. , Dimonie V. L. , El‐Aasser M. S. , Settlemeyer L. A.
Published: April 2003

Dowfax* 2A1 is a branched C12‐alkylated diphenyl ether disulfonate surfactant widely used in industrial emulsion polymerization because of its electrolyte tolerance, stability in concentrated acids and alkalis, oxidation resistance, temperature stability, efficiency in solubilization, and moderate foaming. This surfactant and other similar surfactants were evaluated as emulsifiers in 60 : 40 styrene‐butadiene emulsion copolymerizations carried out at 70°C using persulfate ion initiator, and their solution properties were determined. The similar surfactants were Dowfax 3B2 (linear C10‐alkylated), XD‐8390 (linear C16), XD‐8292 (linear C6), XD‐8174 (linear C12), and various laboratory monoalkylated and dialkylated variations. Sodium lauryl sulfate, Aerosol MA, and Aerosol OT were used as standards for comparison. The emulsifier concentration required to give a 200‐nm particle diameter varied strongly with the degree of alkylation of the emulsifier; the linear C16‐monoalkylated diphenyl ether disulfonate emulsifier gave the desired diameter with the lowest concentration. The adsorption isotherms of these emulsifiers on the 60 : 40 styrene—butadiene copolymer particles were determined and correlated with the emulsifier structure. The interfacial tensions between styrene and the aqueous emulsifier solutions were measured and used to calculate the free energies of micellization and adsorption.
Immobilization of α‐chymotrypsin onto hydrolyzed poly(ethylene)‐g‐co‐hydroxyethyl methacrylate
Authors: Da Silva M. Alves , Gil M. H. , Guiomar A. J. , Martins C. , Guthrie J. T.
Published: April 2003

α‐Chymotrypsin has been immobilized onto partially hydrolyzed poly(ethylene)‐g‐co‐hydroxyethyl methacrylate (120% graft), using 1‐cyclohexyl‐3‐(2‐morpholinoethyl)‐carbodiimide‐p‐toluene‐sulphonate (CMC) as the activating agent. The influence of the enzyme concentration, the carbodiimide concentration, and the coupling medium on the immobilization reaction was studied. A system with 160 mg of coupled enzyme per gram copolymer, providing 126 mg of active enzyme per gram of copolymer was obtained. The KM, Vmax, and the optimum temperature profile and optimum pH value for the free and immobilized α‐chymotrypsin were determined.
The preparation and properties of polyarylate block copolymers by interfacial polycondensation
Authors: Tseng Teng‐Yuan , Chu Ning‐Jo , Lee Yu‐Der
Published: April 2003

Block copolymers of bisphenol A isophthalate and sebacate were prepared by a two‐step interfacial polycondensation. The copolymers had sebacate contents of 1 : 5 and 1 : 3 molar with block lengths (DP) of 4,9, and 19. Thermal analysis of the copolymers by DSC showed the Tm of PBI. The crystallizability of PBI chain segments in the block copolymers was confirmed by X‐ray diffraction. The Tm of the copolymers was primarily influenced by the DP of the chain segments rather than the sebacate content. The Tg of the copolymers was mainly affected by the sebacate content rather than the DP of chain segments. The independent Tg of sebacate in the copolymers was not detected by DSC, i.e., the two polymer chains were compatible without phase separation. Phase separation was only observed in the rheometric spectrum of a 1 : 1 blend of the two homopolymers. The sebacate, being compatible with the isophthalate, had a plasticizing effect upon the polyarylate, which resulted in an improvement in toughness of the copolymers.
Fracture of irradiated polystyrene
Authors: Birkinshaw C. , Buggy M. , O'Neill M.
Published: April 2003

Samples of polystyrene and high impact polystyrene of the butadiene copolymer type, have been subjected to irradiation in air to give received doses of up to 50 Mrad. Tensile and impact properties of the materials were measured using standard techniques. Whilst polystyrene showed little change in mechanical properties with received dose, the two phase high impact material showed significant effects with elongation at break and impact strength being reduced by an order of magnitude over the dose range examined. This behavior is thought to be associated with radiation induced crosslinking in the polybutadiene phase reducing the ability of the rubber to dissipate fracture energy. Micrographs of the tensile fracture surfaces of irradiated high impact polystyrene show evidence consistent with this mechanism.
Catalysis of isocyanate—alcohol and blocked‐isocyanate—alcohol reactions by amidines
Authors: Katsamberis Dimitris , Pappas S. Peter
Published: April 2003

The catalytic activity of completely substituted amidines in the reactions of isocyanates and blocked isocyanates with polyols was investigated. A bicyclic amidine was an effective catalyst for these reactions, whereas the monocyclic caprolactam type amidines were found to be ineffective.
Poly‐1,2,4‐triazoles containing arylene sulfone ether linkages
Authors: Idage Susheela B. , Idage Bhaskar B. , Vernekar Subhash P.
Published: April 2003

Poly‐1,2,4‐triazoles containing arylene sulfone ether linkages have been synthesized by the reaction of polyhydrazide precursors and aniline in polyphosphoric acid at 260°C. The polyhydrazide intermediates were prepared from arylene sulfone ether containing dihydrazides and aromatic diacidchlorides via solution and interfacial polycondensation. These polymers and their intermediates were characterized by infrared, solubility, solution viscosity, elemental analysis, thermogravimetric analysis, differential scanning calorimetry, and X‐ray diffraction.
Grafting of vinyl acetate–methyl acrylate mixture onto cellulose. Effect of ceric ion and nitric acid concentrations
Authors: Fernandez M. J. , Casinos I. , Guzman G. M.
Published: April 2003

The effect of ceric ion and nitric acid concentrations on the graft copolymerization of a mixture of vinyl acetate and methyl acrylate onto cellulose was studied. Two procedures for the reactants addition were employed. Several grafting parameters were determined. Both ceric ion and nitric acid concentrations have a strong effect on the graft copolymerization and they affect similarly some of the polymerization parameters. A variety in the nature of the graft copolymers obtained has been reached. The general behavior of reaction parameters is discussed.
Bulk polymerization of diallyl benzene‐dicarboxylates. II. Effect of temperature on the gel point
Authors: Kostanski Leopold K.
Published: April 2003

The effect of bulk polymerization temperature on the gelation of diallyl phthalate (DAP), diallyl isophthalate (DAI), and diallyl terephthalate (DAT) has been investigated in the temperature range 353–568 K (80–295°C). The critical double‐bond conversion at the gel point increases significantly with temperature in a different manner for each of the monomers: for DAP, from ca. 17% at 353 K up to 46% at 568 K, whereas for DAI and DAT, from 15% and 13.5% up to 32 and 33%, respectively. These values are, on average, four to six times higher than those predicted according to Stockmayer's equation. Surprisingly, the yield of prepolymer precipitated just before the gel point is almost the same for DAP, DAI, and DAT at every polymerization temperature despite different tendencies to cyclization for each of the monomers. The yield increases significantly with the temperature: from ca. 24% at 353 K up to above 60% at 568 K. These yields are four to six times higher than are critical prepolymer contents predicted according to Gordon's theory. Empirical relationships between the gel point parameters and temperature have been developed.
Permeabilities of water, several alcohols, and water/alcohol mixtures through thin films of syndiotactic‐rich poly(vinyl alcohol)
Authors: Yamaura Kazuo , Kirikawa Shuichi , Sakuma Nobuhiro , Tanigami Tetsuya , Matsuzawa Shuji
Published: April 2003

The permeabilities of liquids through syndiotactic‐rich poly(vinyl alcohol) (s‐PVA) very thin films (about 0.3 μm) scooped up from the interface of air/aqueous solution were compared with that of casting s‐PVA films (about 15 μm). The permeability of water decreased with time and the volume of permeate leveled off after 4 or 5 days in both films. In the case of the very thin films, the permeabilities of alcohols decreased with the increase in the molecular weight of alcohol, whereas, in the case of casting films, the permeability of methanol was lower than that of ethanol. In the case of the very thin films, the permeabilities of any water/alcohol (=50/50) mixtures were lower than those of pure water and alcohols. These results were correlated to rearrangement of s‐PVA molecules, formation of bound water, hydrophobic interaction, and clusterization of small molecules.
The transport and sorption of water in polyethersulphone, polysulphone, and polyethersulphone/phenoxy blends
Authors: Swinyard B. T. , Sagoo P. S. , Barrie J. A. , Ash R.
Published: April 2003

Sorption isotherms and steady state permeabilities for water have been measured at 40°C for polyethersulphone, polysulphone, phenoxy polymer, and polyethersulphone–phenoxy blends. The pressure dependence of the permeability in all cases was weak and the permeability of phenoxy polymer is an order of magnitude smaller than that of polyethersulphone and polysulphone. The dependence of the permeability on blend composition is compared with an empirical expression often used to describe transport in miscible blends. The effect of phase separation on the permeability is studied briefly.
Improvement of the processability of advanced polymers
Authors: Nobile M. R. , Acierno D. , Incarnato L. , Amendola E. , Nicolais L. , Carfagna C.
Published: April 2003

The possibility of improving processability of engineering polymers was studied in this work. Low percentages of a thermotropic liquid crystalline polymer supplied by Bayer Co. were added to the polyetherimide Ultem. The thermal and morphological analysis revealed a two phase system. Rheological measurements in shear flow were carried out in the temperature range of the existence of the mesophase. A significant drop of ∼ 30% in the Ultem viscosity occurs even with 5% w/w TLCP. The influence of the addition of the thermotropic polymer on the mechanical properties of Ultem was also investigated. Moreover, the morphological analysis of the unfilled polymers and of the blends was performed and related to their rheological and mechanical behavior.
Thermal decomposition of viscose rayon in the presence of inorganic additives. A kinetic study
Authors: Venkateswaran R. , Babu S. , Kumar S. Sukesh , Pillai M. Aravindakshan , Sharma P. Vishnu
Published: April 2003

Viscose rayon, like many other cellulosic materials, has a thermal decomposition reaction. The rate of change of weight loss of this material is very high at a narrow range of temperatures. When viscose rayon is impregnated with inorganic additives, there is a shift in the temperature of maximum rate of weight loss (Tmax) towards the lower side of the temperature. This effect, due to the addition of ammonium chloride, calcium chloride, and a mixture of calcium chloride and ammonium chloride, was studied in the temperature range 200–400°C through thermogravimetry and the changes observed in the values of activation energy, order of reaction, and char yield are presented in this paper.
Utilization of lignin p‐aminophenyl carbamate as a coupler for dyeing wool and nylon
Authors: Nagieb Z. A.
Published: April 2003

Lignin carbamate was prepared as a good blocking for the phenolic hydroxyl group of lignin. To reduce its color, the following was accomplished: first, condensation of lignin carbamate with p‐nitroaniline to fulfill complete blocking; second, reduction of this compound with thiourea dioxide to give a new compound; and third, diazotization of this new compound with different phenolic compounds to give highly reactive dispersed dyes that have very attractive colors. Lightfastness and washing perspiration fastness were studied, and the relationship between spectral analyses and the fastness was also considered.
Preparation and structural consideration of nitrogen‐containing derivatives obtained from dialdehyde celluloses
Authors: Maekawa Eiichi , Koshijima Tetsuo
Published: April 2003

Nitrogen‐containing derivatives obtained from dialdehyde celluloses were prepared under different pH conditions. On the basis of the results from an analytical data and IR absorption spectra of the products, the structure and characterization of nitrogen‐containing products are discussed and also evaluated concerning a hemialdal seven‐membered cyclic structure proposed by Barry et al. (J. Chem. Soc., 1953, 3631).
The effects of fillers and extenders on the cure properties of phenol–formaldehyde resin as determined by the application of thermal techniques
Authors: Waage S. K. , Gardner D. J. , Elder T. J.
Published: April 2003

The techniques of dynamic mechanical thermal analysis (DMTA) and differential scanning calorimetry (DSC) were used to examine the effects of the addition of various fillers and extenders (clay, pecan shell flour, and wheat flour) on the curing mechanism of a phenolformaldehyde resol. The DMTA results indicated that the curing process was unaffected by any of the additives. The DSC thermograms showed a single exothermic peak that was not influenced to a great extent by the fillers or extenders. Comparison of viscosity measurements and gel time determinations showed slight differences in the physical properties of the uncured resins.
Application of starch xanthates for cadmium removal: A comparative evaluation
Authors: Jawed Mohammad , Tare Vinod
Published: April 2003

Attempts to solve the problem of heavy metals removal and recovery from wastewaters have led to the development and application of several techniques. One of the techniques involves application of starch and cellulose‐based products, especially xanthates. Both water‐soluble and insoluble starch xanthate processes have been claimed to be successful based on the studies conducted with relatively simple wastewaters. The major objectives of this study have been to evaluate the effectiveness of insoluble starch xanthate (ISX) for the removal of cadmium, study the effect of complexing agents/ligands on the interaction of cadmium with ISX and soluble starch xanthate (SSX), and to make overall comparison of ISX and SSX processes for cadmium removal. Both SSX and ISX can bring down the aqueous phase cadmium concentration to less than 1 mg/liter (Indian effluent discharge standard) irrespective of the pH (in the range of 3 to 7), ionic strength, and initial cadmium concentration. The metal binding capacity of ISX is maximum in the pH range of 4 to 5 and is constant irrespective of equilibrium metal concentrations as well as different doses of ISX used at lower pH values (3 to 5). The metal uptake by ISX/SSX in the presence of EDTA is affected considerably. ISX shows higher uptake of cadmium in the presence of EDTA as compared to SSX. The insoluble xanthate process appears to have an edge over soluble xanthate process in terms of metal removal capacity, reliability, and ease of operation, particularly for cadmium.
Mechanical properties of oriented poly(vinyl chloride)–poly(caprolactone) blends
Authors: Ajji A. , Renaud M. C.
Published: April 2003

Blends of poly(vinyl chloride) (PVC) with polycaprolactone (PCL) of different compositions were prepared from solutions in tetrahydrofuran (THF). The dried blends were stretched at different temperatures above the glass transition, and the birefringence and mechanical properties were studied. It is shown that the birefringence of PVC and the 75/25 PVC/PCL blend follows an affine deformation scheme with a decreasing number of segments with deformation. The 50/50 PVC/PCL blend shows a complex orientation behavior because of the presence of crystallinity in the PCL phase. The mechanical properties of the blends are shown to increase with orientation, and the aggregate model is acceptably followed by the amorphous oriented blends.
Polyamides and polyesters with improved mechanical properties
Authors: Fakirov Stoyko , Evstatiev Michail , Schultz Jerold M.
Published: April 2003

An attempt is made to establish the most proper initial structure for the obtaining of highly drawn (at room temperature) nylons and polyesters. It is found that neither the completely crystalline structure nor the fully amorphous one but a low‐crystallinity, very imperfect structure (with a large number of small crystallites) is the most suitable one. Through ultraquenching of nylon 6 and PBT melts, and storage at ambient conditions, draw ratios of 7 and 8, respectively, are achieved. Subsequent annealing results in the obtaining of doubly higher values of the elasticity modulus and tensile stress. By means of WAXS, SAXS, IR spectroscopy, and DSC measurements the obtained structure is characterized. The highly drawn and annealed samples show a strongly reduced concentration of chain folds and a lack of long spacing.
Removal and recovery of gallium and indium lons in acidic solution with chelating resin containing aminomethylphosphonic acid groups
Authors: Maeda Hironori , Egawa Hiroaki
Published: April 2003

Removal and recovery of gallium and indium ions in acidic solution with the macroreticular chelating resin containing aminomethylphosphonic acid groups was investigated. The resin (RMT‐P) exhibited high affinity for gallium and indium ions in sulfuric acid solution. In the column method, gallium and indium ions in sulfuric acid solution (0.05 or 0.5 mol/dm3) were favorably adsorbed on the RMT‐P when the solution containing 27.6 mg/dm3 of gallium ion or 51.4 mg/dm3 of indium ion was passed through the RMT‐P column at a space velocity of 15 h−1. The gallium and indium ions adsorbed were eluted by allowing 1 mol/dm3 sodium hydroxide or 4 mol/dm3 hydrochloric acid to pass through the column. The proposed resin appears to be useful for the recovery of gallium and indium ions in sulfuric acid solution.
Carboxyl‐terminated poly(propylene glycol) adipate‐modified room temperature curing epoxy adhesive for elevated temperature service environment
Authors: Achary P. Sasidharan , Gouri C. , Ramaswamy R.
Published: April 2003

An investigation was carried out into the effect of modification of an epoxy resin with carboxyl‐terminated poly(propylene glycol) adipate (CTPPGA) liquid rubber, on room temperature and elevated temperature adhesive joint strengths, after curing at room temperature (25°C) with tris‐2,4,6‐(N,N‐dimethyl amino methyl) phenol hardner. CTPPGA prepared by the esterification of poly(propylene glycol) (PPG) and molar excess of adipic acid was incorporated into the epoxy resin by the prereact method. CTPPGA modification showed significant enhancement of adhesive joint strengths over the unmodified epoxy and the joint strengths were found to depend on the molecular weight of CTPPGA and its content in the epoxy resin. The elevated temperature lap shear strength measurement made for the CTPPGA‐modified epoxy adhesive showed that the adhesive formulation has a temperature service capability up to 120°C. The results are discussed in terms of the data obtained from the tensile tests, DSC analysis, and SEM observations of the fractured surfaces.
Grafting of vinyl acetate–methyl acrylate mixture onto cellulose. Effect of inorganic salts
Authors: Fernandez M. J. , Casinos I. , Guzman G. M.
Published: April 2003

The effect of the addition of NaNO3 and NaCl on the graft copolymerization of a mixture of vinyl acetate–methyl acrylate onto cellulose, using ceric ion as initiator, is examined. Several grafting parameters were measured. Presence of NaNO3 affects the graft copolymerization by enhancing the cellulose oxidation, but it leaves almost unaffected the homopolymerization reaction. NaCl works similarly to NaNO3. As a consequence of salt presence, ligand changes in the ceric ion complexes, as well increase in the ionic strength of the medium, are expected.
Effect of amines on the carbanilation of cellulose with phenylisocyanate
Authors: Evans Robert , Wearne Ross H. , Wallis Adrian F. A.
Published: April 2003

Various amines were added to carbanilation reactions of cellulose samples with phenylisocyanate in an effort to aid the preparation of cellulose tricabanilates (CTCs) for determining molecular weight distributions (MWDs). However, the amines catalyzed the conversion of phenylisocyanate to its trimer phenylisocyanurate, especially in dimethylsulfoxide (DMSO) and N,N‐dimethylformamide (DMF) media. In some of the reactions to which amines were added, the CTC products had high‐performance size exclusion chromatographic peaks that tailed badly. The tailing was not caused by incomplete carbanilation. The amines 1,4‐diazabicyclo (2.2.2) octane (DABCO) and 4‐N,N‐dimethylaminopyridine (DMAP) accelerated the dissolution of cellulose during carbanilation, while others retarded the dissolution. DABCO in pyridine assisted the carbanilation of cellulose samples, which were otherwise unreactive in pyridine, although the reactions were slower than in uncatalyzed DMSO media. However, the reactions in DMSO with added amines gave CTCs with lower degree of polymerization (DP) values, and the DP reduction was particularly severe when N‐methylimidazole was the added amine. The possible involvement of oxidation by DMSO in the depolymerization process is discussed. It was concluded that addition of amines to carbanilation reactions of cellulose has limited application for CTC preparation for MWDs.
Crystallinity and lateral crystallite size of different UHMW PE materials
Authors: Hofmann D. , Schulz E. , Fanter D. , Fuhrmann H. , Bilda D.
Published: April 2003

Nascent high‐molecular‐weight (UHMW) polyethylene (PE) samples of different origins show a rather high crystallinity of about 70–75% and contain both a major portion of orthorhombic extended chain crystallites and a minor portion of triclinic crystallites. The triclinic content is greater the higher the molecular weight of the sample and the higher the activity of the used catalyser. A melting / recooling treatment results in a reduction of crystallinity by about 15–25% and disappearance of the triclinic phase. Further, an irreversible conversion of nascent orthorhombic extended chain crystallites to orthorhombic folded chain crystallites of increased lateral dimensions and crystalline perfections takes place during the melting / recooling treatment. The results are compared to those obtained for lower‐molecular‐weight PE samples and for high‐strength / modulus PE fibers of different origins.
Effect of preextension on electrical conductivity and physicomechanical properties of butyl rubber (IIR) loaded with different types of carbon black
Authors: Hashem A. A. , Ghani A. A. , Eatah A. I.
Published: April 2003

The effect of preextension on the variation of the electrical conductivity (σ) of butyl rubber (IIR) loaded with high abrasion furance (HAF) and fast extrusion furance (FEF) carbon black with carbon concentration have been investigated. The change in σ has been explained as a result of the interaction between carbon and rubber and the effect of the occluded rubber.

The effect of preextension on the electrical resistivity (ρ) variation with strain has also been studied. The changes have been interpreted as being due to either breakdown or reagglomeration, depending on the concentration of carbon black.
Theoretical modification of the finely porous model for reverse osmosis transport
Authors: Mehdizadeh H. , Dickson J. M.
Published: April 2003

One of the most significant models used to describe and predict the performance of reverse osmosis type membranes is the finely porous model (FPM). In this paper, the basic assumptions of the model are examined and modified. The two most serious problems with FPM are that an incorrect form of material balance on the solute is used and that the osmotic pressure effects are not completely taken into account for electrolytes. A modified model (called MD‐FPM), which is based on the same physical precepts is derived. Equations describing the concentration profile for both models have been derived and compared. It has been shown that the FPM can predict physically unacceptable results. Difficulties in using the parameters from the model for prediction or for membrane development work are discussed. Simulation results for the MD‐FPM model are consistent with what is expected for reverse osmosis type membranes.
Studies of macromolecular entanglements. I. Melting behavior of swelling polymers with macromolecular entanglements
Authors: Qian Baojun , Wu Zongquan , Hu Panpan , Qin Jian , Wu Chengxun , Zhao Jiongxin
Published: April 2003

In this paper the swelling and melting behavior of several polymers, particularly acrylic fibers, is studied by thermomicroscopy and differential scanning calorimetry in detail. It is confirmed that the protrusion peak on the tail part of the DSC thermogram of swelling polymers is closely associated with the macromolecular entanglements. The proposed swelling DSC method is proved to be very effective for studying polymer entanglements. It is also shown that the melting point, whether of paracrystalline region or of entanglement structural unit, can be well fitted to Flory's melting point depression theory.
Electrochemical polymerization of N‐vinylcarbazole
Authors: Bhadani Suraj N.
Published: April 2003

The electrolysis of N‐vinylcarbazole in the solution of quaternary ammonium salts in dichloroethane leads to polymer formation in the anolyte. The effect of monomer concentrations, current levels, and nature of supporting electrolytes on the polymerization has been investigated. The polymerization is free radical with bromide salt and cationic with perchlorate or hexachloroantimonate salt. The poly(N‐vinylcarbazole) gets oxidized at the anode and can be cycled between the oxidized and neutral states. The oxidized polymers at the electrode may exhibit electrical conductivity.
Solvent‐induced crystallization in polyetherimide thermoplastics and their carbon fiber composites
Authors: Nelson K. M. , Seferis J. C. , Zachmann H. G.
Published: April 2003

Solvent‐induced crystallization (SINC) was observed in a polyetherimide (PEI), a thermoplastic used as a matrix in carbon fiber composites. This observation was made using wide angle X‐ray scattering (WAXS), differential scanning calorimetry (DSC), and optical microscopy. It was discovered that methylene chloride induces crystallization in the PEI by penetrating the surface and swelling the bulk polymer. Prepreg processed using N‐methyl pyrrolidone (NMP) was also crystalline. One processed above the crystalline melting point (Tm), no crystallinity in the sample was found, as the PEI did not crystallize from the melt. The observed crystallization of both the neat polymer and its carbon fiber prepreg was exclusively through a solvent‐induced process, although it is likely that the mechanism through which crystallization occurs during solvent prepreg processing is different than the diffusion‐controlled mechanism demonstrated with methylene chloride. A solvent prepregging process may involve a low molecular weight or monomer solution as well as other polymerization by products. Measurements using WAXS showed a maximum degree of crystallinity of 30%, as induced by methylene chloride. A value of 85 J/g for the heat of solvent‐induced crystallization in the PEI was calculated from the DSC measurements.
The effect of gamma ray irradiation on the mechanical properties of large cross‐section oriented polyethylene rods
Authors: Sangster D. F. , Barry D. B.
Published: April 2003

The effect of gamma irradiation, in acetylene, on large diameter oriented polyethylene has been investigated. The dependency of gel content, melting point, and crystallinity on dose was evaluated. The gel content dose relationship showed two regions, indicating that an effective network is formed at low doses, 60 kGy. Irradiating the oriented rod in acetylene was found to more than double the initial tensile modulus. This improvement in the tensile properties resulted in improved creep–strain resistance for the material. These improvements in the mechanical properties were attributed to crosslinks formed both in the amorphous regions and at the surfaces of the crystalline regions. At high does > 180 kGy degradation of the oriented polymer resulted in a deterioration in mechanical properties.
Hydroperoxidation of EPDM rubber using singlet oxygen: Synthesis and grafting studies
Authors: DeRosa T. F. , Kaufman B. J. , Broas J. E.
Published: April 2003

Chemically generated singlet oxygen hydroperoxidizes the ethylidene double bond in terpolymers of ethylene, propylene, and ethylidene norbornene (EPDM rubber). The EPDM–hydroperoxide was reduced exclusively to 2‐(1‐hydroxylethyl)‐norborene‐EPDM rubber using either triphenylphosphine or sodium sulfite. Thermal decomposition of EPDM–hydroperoxide in the presence of either methyl methacrylate or 2‐ or 4‐vinyl pyridine free radically grafted these monomers to the rubber. In the absence of graftable monomer, however, thermal decomposition of EPDM‐hydroperoxide generated an intractable polyether.
Copolymerization of alkyl methacrylates with triallyl cyanurate. Determination of monomer reactivity ratios
Authors: Ryttel Anna
Published: April 2003

The free‐radical copolymerization of propyl, pentyl, hexyl, heptyl, octyl, and dodecyl methacrylates with triallyl cyanurate was investigated. The reactivity ratios were determined using the methods of Fineman‐Ross and Kelen‐Tüdös. The Alfrey‐Price Q and e values for the methacrylates were also evaluated. The effect of the length of alkyl group in methacrylates on reactivity ratios is discussed.
Superstructure in ultrahigh speed spun fibers of poly(ethylene terephthalate)
Authors: Fujimoto K. , Iohara K. , Ohwaki S. , Murase Y.
Published: April 2003

Ultrahigh speed spinning of poly(ethylene terephthalate) (PET) was carried out at various take‐up velocities from 5 to 10 km/min. The superstructure of as‐spun fibers was characterized by small‐angle X‐ray scattering (SAXS), wide‐angle X‐ray diffraction (WAXD), viscoelastic properties, and scanning electron microscopy (SEM). Above 6 km/min the peaks or shoulders that are due to the interference between microfibrils appear on the equatorial SAXS intensity curves. The interfibrillar spacing estimated from the peak position increases with increasing take‐up velocity. Comparison of the spacing with the lateral crystal sizes estimated from the broadness of the crystal (hk0) WAXD peaks indicates that the microfibril diameter becomes thick with increasing take‐up velocity. Although the orientation and density in amorphous region for high‐speed spun fibers are very low on the average, it can be seen that a few highly extended tie molecules exist in that region, and the number of these molecules increases with increasing take‐up velocity. The modes and mechanisms of fibrillation induced by a rubbing test are discussed relating to these results.
Empirical modelling and scale‐up of a semi‐batch polyestrification process
Authors: Dairanieh Issam S. , Khraishi Nadia
Published: April 2003

A semi‐empirical kinetic model that fits laboratory data and predicts pilot plant data was developed. The model is a modified version of a recently reported third‐order kinetic equation for the reaction of nonstoichiometric amounts of hydroxyl and carboxylic groups. The model can be used to quantify the effects of reaction temperature and inert gas flow rate on the reaction rate. The Arrhenius temperature dependence of the rate constant permitted the calculation of the reaction activation energy (53.6 kJ/mol). The gas flow rate dependence is an empirical function of the molar ratio of reactants to inert gas. The same function is simultaneously used as the process scale‐up rule. The mathematical model can be potentially used for commercial‐sized reactors.
A pseudouniversal calibration procedure for the molecular weight determination of cellulose
Authors: Vidal P. F. , Basora N. , Overend R. P. , Chornet E.
Published: April 2003

Size‐exclusion chromatography of carbanilated cellulose of polystyrene‐divinylbenzene packing has been used to determine the molecular weight distribution of the polymer with tetrahydrofuran as the eluent. The reproducibility and the accuracy of the method is discussed in this paper with reference to depolymerized organosolvent‐treated celluloses. A comparison between the results obtained from the universal calibration approach and the viscosity‐average degree of polymerization, derived from the determination of the intrinsic viscosity in cupriethylene diamine solutions, is presented
A highly fluorinated epoxy resin. III. Behavior in composite and fiber‐coating applications
Authors: Twardowski T. E. , Geil P. H.
Published: April 2003

The behavior of a highly fluorinated epoxy resin used as a composite matrix material with AS‐4 fibers and as an AS‐4 fiber coating was studied. The composite mechanical properties were obtained, and the adhesion of the matrix to the fibers was evaluated. Comparisons of uncoated and fluoropolymer coated AS‐4 fibers using single fibers embedded in an Epon 828 matrix were made. Substantial improvement in fiber critical length, and therefore fiber‐matrix adhesion, was observed.
A rheological model for iron oxide suspensions
Authors: Lin Yih‐Shen , Liu Ta‐Jo , Chu Ning‐Jo
Published: April 2003

We have examined the rheological properties of a Co‐adsorbed γ‐Fe2O3 magnetic suspension with polyurethane (PU) as a binder and methyl ethyl ketone (MEK) or cyclohexanone (CH) as a solvent. A Haake RV20 viscometer was used to measure the suspension viscosity and the vane method was adopted to determine the fluid yield stress. A rheological model which can be viewed as a combination of the Casson model and the Bingham model is proposed to describe the suspension viscosity. The effects of temperature, particle content, and binder concentration are included in the model.
Separation of liquid mixtures by using polymer membranes. III. Water–alcohol separation by pervaporation through modified PAN membrane
Authors: Hu Chun‐Min , Chiang Wen‐Yen
Published: April 2003

The modification of polyacrylonitrile membrane with ethanolamine was carried out, and the permeation characteristics in pervaporation were examined using the aqueous alcohol solutions. In pervaporation of a water/alcohol solution, preferential permeation of water was observed for all these membranes because of the hydrogen‐bonding interaction. The selectivity of the modified polyacrylonitrile (PAN) membrane depended on operating temperature, but was independent on the thickness of the membrane. Furthermore, it was found that the membrane with more ethanolamine content had a higher affinity to water. The effect of feed concentration and the molecular size of the permeating species on the separation factor and permeation flux was also investigated.
Gel permeation chromatography of isotactic polypropylene using the cyclohexane–decalin solvent system
Authors: Ibhadon A. O.
Published: April 2003

The molecular weight distribution of iPP and its copolymers with ethylene have been studied using cyclohexane/decalin as eluent at 333 K. The fractionation of the polymers using the same solvent system was also investigated. Reproducible and reliable molecular weight distribution and averages have been obtained.
New peracid‐type polymeric initiator for radical polymerization
Authors: Hsiue Ging‐Ho , Perng Tirng‐Lair , Yang Jen‐Ming
Published: April 2003

In this study, a radiation‐induced copolymer, namely polyethylene‐g‐acrylic acid powder, was used, whose carboxyl groups can be oxidized to form a highly reactive polymer initiator. The activation energy for its decomposition is 22.4 kcal/mol. It was found that the peracid‐type polymeric powder was effective as an initiator for radical polymerization. It had high reactivity toward 2‐hydroxyethyl methacrylate (HEMA), which could be easily grafted onto the polymeric powder; also, the homopolymer could be obtained. The kinetic investigation indicated that this polymerization proceeded by a radial mechanism, and the overall activation energy of homopolymerization was 18.67 kcal/mol and the overall activation energy of bigraft polymerization was 17.35 kcal/mol. By using the peracid‐type polymeric powder as initiator for the copolymerization of methyl methacrylate with styrene, it was confirmed that the polymerization initiated by the peracid‐type polymeric powder was a radical reaction.
Flow injection analysis estimation of diffusion coefficients of pauci‐ and polydisperse polymers such as polystyrene sulfonates
Authors: Boyle William A. , Buchholz Richard F. , Neal John A. , McCarthy Joseph L.
Published: April 2003

Flow injection analysis, often used for determination of diffusion coefficients of nonpolymeric substances, has now been applied to the characterization of pauci‐ and polydisperse polymers in solution. A relative method was found useful for obtaining moderate quality evaluations of diffusion coefficients and related parameters of polymers. The width at half‐height W1/2 of the trace peak is found to be proportional to the number average molecular weight M̄n of pauci‐ and polydisperse polymers, allowing estimation of M̄r and diffusion coefficients. For sodium polystyrene sulfonates at substantially infinite dilution in 1.0 g L−1 Na2SO4, a linear relation has been observed between the logarithms of the molecular weight M̄n and the mean diffusion coefficient D in the M̄n range of 1000–90,000 g mol−1 or the D range of 30 × 10−7 to 2 × 10−7 cm2 s−1.
Thermal stability of nonionic polyoxyalkylene surfactants
Authors: Santacesaria E. , Gelosa D. , Di Serio M. , Tesser R.
Published: April 2003

Nonionic surfactants are largely employed in the pharmaceutical, cosmetic, and textile industry. The sensitivity of polyoxyethylene chains to autoxidation is studied because it is responsible for unpleasant effects such as discoloration, degradation of products, and unpleasant odors. In the present work, thermal stability of polyoxyethylene and polyoxyethylene/propylene nonionic surfactants has been studied by employing together differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). First of all, the thermal stability of three monodispersed surfactants (laurilic alcohol plus 4, 6, or 8 EO units) has been studied. Then, the behavior of these products has been compared with those of commercial surfactants containing the same alkyl chain coupled with idrophylic chains of different lengths, containing EO units alone or both EO and PO. The effect of the alkyl chains has also been examined in the same way. In all cases, autoxidation starts at about 100°C with a net heat production proportional to the number of adducts and equal to about (1.5–1.7) × 105 J/adduct. Heat evolution stopped at about the same temperature, independently of the hydrophylic chain length. A residual of 10–30% by weight decomposes, at higher temperatures, with a very small heat evolution. The interpretation of these and other phenomena observed conclude the paper.
High‐temperature continuous bulk copolymerization of styrene and acrylic acid: Thermal behavior of the reactants
Authors: Spychaj Tadeusz , Hamielec Archie E.
Published: April 2003

The behavior of the monomers: styrene (St) and acrylic acid (AA) during the process of thermally initiated bulk copolymerization realized in a continuous stirred tank reactor (CSTR) is discussed in this work, on the basis of results obtained from experimental work carried out by the authors and data available from literature. GPC, GC, IR, and NMR techniques were used to examine the volatile oligomers released from the raw St–AA polymers. The mechanism of the thermal initiation of polymerization in the system under investigation is also discussed. Polymer degradation reactions in the vicinity of the ceiling temperature Tc, chain transfer reactions, and secondary reactions of carboxylic groups in high temperatures have also been considered. The behavior of the St–AA polymers during derivatographic tests in the temperature range: ambient−400°C, conducted in atmospheric air, was also evaluated. Experimental conditions, in which deep destruction of the product during the copolymerization process could be avoided, were established.Knowledge of these conditions is important from a practical point of view.
Spectroscopic study on poly(methyl methacrylate) doped with metal dithizonates
Authors: Moharram M. A. , Shabaka A. A. , Khafagi M. G.
Published: April 2003

The IR and UV spectra of poly(methyl methacrylate) (PMMA) doped with metal dithizonate were investigated. Films of the doped samples were heated in air at various temperatures from 25 to 140°C for 2 h. Other films were also exposed to UV irradiation. The doped samples were treated with iodine. The experimental results provided strong evidence that certain weak reaction occurs between the dopants and the polymer, and the rate of reaction depends on the concentration of the dopant and the nature of the metal ions. It was found that heat treatment of the doped films induces considerable changes in the intensities of their IR bands. The magnitude of these changes depends also on the concentration and the nature of the metal ion. Moreover, the results proved that exposure of the doped films to UV irradiation has no effect on their absorption spectra. Furthermore, the treatment of the doped samples with iodine causes considerable changes in their UV absorption spectra.
The use of aqueous alkaline hydrolysis to reveal the fine structure of poly(ethylene terephthalate) fibers
Authors: Collins Martha J. , Zeronian S. Haig , Semmelmeyer Mary
Published: April 2003

The fine structure and physical properties of bright and semidull poly(ethylene terephthalate) (PET) fibers were investigated as successive layers of the polymer were removed by hydrolysis using aqueous solutions of sodium hydroxide up to weight losses of 90 and 68%, respectively. For both types large changes in molecular weight distribution did not occur, although as weight loss increased, the density of the remaining fiber increased. Alterations in fine structure with weight loss were also observed by thermal analysis. Greater strength loss with decreasing weight occurred for the semidull fiber than for the bright sample. Larger pits formed on the surface of the hydrolyzed semidull fibers than on the surface of the bright products. This observation is attributed to the titanium oxide present in the semidull fibers. It was also noted that as the density of the bright PET samples was increased by heatsetting, the rate of hydrolysis decreased.
Arylidene polymers. VI. Gamma irradiation effects on the electrical conductivity behavior, IR absorption spectra, and DSC measurements of some new synthesized poly(arylidenecycloalkanones)
Authors: Abd‐Alla M. A. , Mahfouz R. M.
Published: April 2003

Gamma irradiation effects on the electrical conductivity behavior of some new synthesized poly(2,5‐arylidenecyclopentanone) 1, poly(2,6‐arylidenecyclohexanone) 2, and their co‐polymers 3, have been investigated. Thermal studies over the temperature range 300‐500 K showed that the conductivity behavior follows a two‐term Arrhenius‐type equation. The first term has a small activation energy and predominates at lower temperature (extrinsic region), and the second term with higher activation energy predominates at higher temperatures (intrinsic region). Change in the activation parameters with the change in the γ‐ray dose and the nature of the polymers are discussed. The IR absorption spectra showed a decrease in the intensity of most bands of the γ‐irradiated samples. A mechanism based on the formation of trapped free radicals and their recombination has been suggested. DSC measurements indicated that the crystallization and the melting temperature transitions decreased in size considerably with the increase in the γ‐ray dose until they nearly disappeared at higher γ‐ray dose.
Surface and interfacial FTIR spectroscopic studies of latexes. III. The effects of substrate surface tension and elongation on exudation of surfactants
Authors: Evanson Kevin W. , Urban Marek W.
Published: April 2003

This paper focuses on the effect of the substrate surface tension and mechanical elongation of EA/MAA latex films on the ionic and nonionic surfactant mobility. Although the mobility of anionic surfactants is inherently sensitive to the substrate surface tension, nonionic surfactants appear to remain uniformly distributed across the latex film. This behavior is attributed to the enhanced compatibility with the copolymer latex. Mechanical elongation of the latex films enhances surfactant exudation to the surface due to the increased surface energy of the film forcing surfactants to the latex surface.
Influence of glycine on the kinetics of the graft copolymerization of acrylonitrile onto jute fibers initiated by ceric ion
Authors: Nayak N. C. , Das H. K. , Singh B. C.
Published: April 2003

A study of the influence of glycine on the graft copolymerization of acrylonitrile (AN) onto jute fiber using ceric ion has been made. The effect of concentrations of monomer, Ce (IV), and glycine on graft yield have been studied. In addition, the effect of time, temperature, acid, and the amount of jute fiber on graft yield has been investigated. On the basis of experimental findings, a qualitative reaction mechanism has been proposed and the optimum condition for effective grafting has been suggested.