bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis of new polymers containing tannin
Authors: Kim Min , Saito Kyoichi , Furusaki Shintaro , Sugo Takanobu , Okamoto Jiro
Published: April 2003

A novel method for preparation of immobilized tannin on polyethylene has been suggested. A tannin‐containing polymer was prepared by radiation‐induced graft polymerization of glycidyl methacrylate onto porous polyethylene, followed by coupling tannin with the produced epoxide group. Reaction conditions for preparing immobilized tannin, such as the reaction temperature, pH, and the molar ratio of tannin to the epoxide group were investigated. The tannin content of the tannin‐containing porous polyethylene was 20%, which is approximately equivalent to that of the conventional cellulose‐based immobilized tannin. The adsorption isotherm for immobilized tannin and ferrous ion was determined.
Diffusion‐controlled kinetics for the solution copolymerization of 2‐ethylhexyl acrylate with vinyl chloroacetate in a CSTR
Authors: Das Siddhartha , Rodriguez Ferdinand
Published: April 2003

The solution copolymerization of the comonomer pair 2‐ethylhexyl acrylate–vinyl chloroacetate (in ethyl acetate) has been studied in a continuous stirred tank reactor (CSTR). The initiator used in this study, 2,2′‐azobis‐2,4‐dimethyl valeronitrile was selected on the basis of its high decomposition rate constant. Measurements included the rate of copolymerization, the copolymer composition by infrared spectrophotometric analysis, the molecular weight distribution by gel permeation chromatography, and the viscosity of the reaction mixture by capillary viscometry. The reactivity ratios for the EHA–VCLAC pair were markedly different so that both propagating chains preferentially add EHA. Both the ϕ factor and the penultimate effect models were inadequate for describing the termination reaction. By defining an appropriate expression, based on physicochemical considerations, for the overall termination rate constant, it was possible to model the steady state rates by the diffusion model of Atherton and North. An attempt to model the transient behavior of the reactor by using the ϕ value as an adaptable correction factor was unsuccessful due to the rapid composition drift during approach to steady state. The measured conversions were lower than the model predictions for all feed ratios.
Studies of selective adsorption resins. XXVI. Removal of calcium and magnesium ions in a salt solution with chelating resin containing aminomethylphosphonic acid groups
Authors: Maeda Hironori , Egawa Hiroaki
Published: April 2003

Removal of calcium and magnesium ions in a salt solution with the macroreticular chelating resin containing aminomethylphosphonic acid groups was investigated. The resin (RMT‐P) exhibited high affinity for calcium and magnesium ions in a salt solution containing 200 g/dm3 of sodium chloride. In the column method, calcium and magnesium ions in a salt solution were preferentially absorbed on the RMT‐P, when the salt solution containing 100 mg/dm3 of calcium or magnesium ion was passed through the RMT‐P column at a space velocity of 15 h−1. The calcium and magnesium ions adsorbed were eluted by allowing 1 mol/dm3 hydrochloric acid to pass through the column. The recycle of adsorption and elution was found to be satisfactory.
Catalytic dehydrochlorination of the solid poly(vinyl chloride) in the presence of aluminium chloride (friedel‐crafts) catalyst: Studies of the structure by spectroscopical methods
Authors: Rabek Jan F. , Lucki Julia , Kereszti Henryk , Hjertberg Tomas , Jun Qu Bao
Published: April 2003

Catalytic dehydrochlorination (100%) of solid poly(vinyl chloride) (PVC) in the presence of AlCl3 at 200°C gives a product which has a similar structure to the product of catalytic dehydrochlorination of 1,2‐dichloroethane in the presence of AlCl3 at 60°C. Both products have brown‐black color, are completely insoluble, thermally resistant up to more than 400°C, and exhibit conductivities in the range 10−6 S cm−1 (after doping with FeCl3 or I2 conductivities: 10−5 S cm−1). Different spectroscopical methods such as UV/VIS, IR, Raman, ESCA, and 13C‐NMR were employed to the structure study of both products, which are crosslinked polyenes with a number of aromatic rings.
Thioether glycidyl resins. VII. Products of condensation of bis(4‐mercaptophenyl)sulfide and bis(4‐mercaptophenyl)sulfone with epichlorohydrin
Authors: Charmas Władysław , Podkościelny Wawrzyniec , Rudź Wiestaw
Published: April 2003

New thioether glycidyl resins by condensation of bis(4‐mercaptophenyl)sulfide or bis(4‐mercaptophenyl)sulfone with epichlorohydrin were obtained by heterophase alkaline condensation in aqueous and isopropanol medium using sodium hydroxide. The detailed studies on their structures from elemental analysis and IR and 1H‐NMR spectra, physical and chemical properties, and curing conditions are presented. Thioether glycidyl resins compositions were also prepared using curatives typical for epoxy resins and after curing they were characterized from derivatographic, thermomechanical, and mechanical studies.
Synthesis and properties of hydrophilic copolypeptide membranes containing L‐aspartic acid as one component
Authors: Hayashi Toshio , Iwatsuki Makoto , Oya Masanao
Published: April 2003

Three‐component random copolypeptide consisting of N‐hydroxypropyl‐L‐glutamine, L‐aspartic acid, and L‐lysine, related two component random copolypeptides and homopolypeptides, were prepared by carrying out aminolysis reaction with 3‐amino‐1‐propanol, followed by crosslinking reaction with 1,8‐octamethylenediamine on starting polymer membranes consisting of γ‐methyl‐L‐glutamate, L‐aspartic acid, and L‐lysine. The effective crosslink density was shown to be proportional to the content of the crosslinker in the reaction mixture. The tensile properties of these hydrophilic membranes were highly dependent on the degree of swelling in the pseudoextracellular fluid, hydrophobicity of the side chains, and the effective charge density of membranes, and their behavior was typical of an elastomer. A higher rate of water permeability was obtained with charged membranes than noncharged and/or compensated charged membranes with the same order of the degree of swelling in the pseudo‐extracellular fluid. Biodegradation of the samples in vitro by papain indicated that the degradation could be regarded as a bulk rather than a surface phenomenon. The rate of degradation was also highly dependent on the degree of swelling of membranes, as well as on the hydrophobicity and the effective charge density of side chains of sample membranes.
SSIMS analysis of methacrylate copolymers employed in drug delivery
Authors: Wilding Ian R. , Melia Colin D. , Short Robert D. , Davies Martyn C. , Brown Alan
Published: April 2003

This study reports on the use of static secondary ion mass spectroscopy (SSIMS) to chemically characterize complex methacrylate copolymers used in the pharmaceutical industry for controlled drug delivery. Ions diagnostic of the component monomer residues were detected, which could be interpreted using a fragmentation model for alkylmethacrylate homopolymers proposed previously. This model is extended to include the SSIMS analysis of nitrogen‐containing methacrylate copolymer residues.
On the possibilities of immobilization and utilization of some cellulase enzymes
Authors: Simionescu Cristofor I. , Popa Valentin I. , Popa Mariana , Maxim Steliana
Published: April 2003

Cellulase enzymes produced by the microorganisms Aspergillus niger and Trichoderma viride have been immobilized on Ponilex type ion exchangers, both by ionic and by covalent bonding. Immobilization efficiency has been determined for enzyme preparations obtained, by their activity, as well as by that of the resulted effluent, on using as substrate carboxymethyl cellulose, cellobiose, and filter paper. The catalytic activity of the immobilized products has been tested against solutions of carboxymethyl cellulose and a series of hemicellulose containing alkaline extracts resulted from the alkaline pretreatments of some vegetal materials. The presence of polyphenol compounds in the latter ones determines a series of peculiarities in the behavior of the enzyme preparations, such as the transformation of the hydrolysis products and reduction of thecatalytic activity of the enzyme, after a certain period of reaction.
Effect of additives on the degradation of acrylamide–acrylic acid copolymer in aqueous solution
Authors: Kheradmand Houchang , François Jeanne , Plazanet Veronique
Published: April 2003

This paper presents the results of a systematic study of the effect of different additives on the degradation of acrylamide–acrylic acid copolymers at high temperature. Under conditions of current applications in enhanced oil recovery (without oxygen and in the presence of ferrous ions), the effects of sodium azide, sequestrant DTPA, and isobutanol have been separately tested. It is shown that DTPA enhances degradation when ferrous ions are present. A new process of stabilization which may be efficient in most of the conditions is proposed.
Polysulfone hollow fiber membranes spun from lewis acid: Base complexes. II. The effect of lewis acid to base ratio on membrane structure
Authors: Fritzsche A. K. , Cruse C. A. , Kesting R. E. , Murphy M. K.
Published: April 2003

Oxygen plasma ablation has been used to define the structure of polysulfone hollow fiber membranes spun from Lewis acid:base complex solvents in which the molar ratio of propionic acid to N‐methylpyrrolidone was varied. It was found that the helium/nitrogen separation factor of the unetched samples increases with increasing PA/NMP molar ratios. This increase implies a decrease in surface porosity of the resultant hollow fiber as larger fractions of the total NMP in the solvent are complexed with propionic acid. The results also suggest that the differences between the outer separating layer and the supporting matrix increase with increases in the PA/NMP molar ratios. Therefore, a more rapid transition from the separating layer to the porous supporting matrix exists in hollow fiber membranes spun from the higher PA/NMP ratios.
Study of the factors affecting the electrical conductivity of zinc–polycarboxylate cement
Authors: Sawaby A. , Moharam M. A. , Tahon Kh.
Published: April 2003

The behavior of the electrical conductivity of polycarboxylate cement with temperature was studied from room temperature up to 160°C. The effects of powder/liquid ratio, mixing temperature, percentage of MgO in the powder, and aging on this behavior were also investigated. The results obtained revealed that the electrical conductivity decreases with increasing the powder/liquid ratio and with decreasing mixing temperature and the amount of MgO in the powder. The reason for the changes of the conductivity due to the mentioned factors were discussed.
Studies on irradiation of agar–agar in the solid state: On the changes of X‐ray diffraction of agar–agar film produced by irradiation
Authors: Nisizawa M. , Hirano T.
Published: April 2003

Solid agar–agar was irradiated with 60Co gamma‐rays, dissolved in aqueous solutions, molded and made a thin film. Effects of radiation on the ordered conformation of agar–agar molecule were studied by measuring the X‐ray diffraction intensity at different radiation doses, elapsed times after irradiation, and concentrations of added substances (sugar and starch). Empirical equations in changes of X‐ray diffraction were obtained.
Gas transport in lanthanide‐polymer membranes
Authors: Dong Jian‐Hua , Huang Xiao , Huang Chang‐Kai , Jiang Ying‐Yan
Published: April 2003

Permeation properties of O2, N2, and CO2 were investigated by using copolymer membranes having the pyridine‐lanthanids complexed group. The membranes of poly(4‐vinylpyridine‐co‐n‐butylmethacrylate) and its complexes with lanthanide were prepared. Complexation with lanthanide can be used to tailoring selectivity of CO2/O2. The CO2 permeability for lanthanide‐polymer, which is oppsite to most polymers. the upstream pressure dependent of grass in lanthanide‐polymer varies with temperature. A tentative explanation is given for the results according to the free colume model.
The physical mechanism for the production of hydrophilic polymer microparticles from aqueous suspensions
Authors: Scranton Alec B. , Mikos Antonios G. , Scranton Lisa C. , Peppas Nikolaos A.
Published: April 2003

A previously reported method of producing spherical, hydrophilic microparticles by aqueous suspension polymerization is experimentally investigated. The phase separation is the result of a salting‐out phenomenon. Characteristics of the salting‐out effect between the monomer and suspending phase of aqueous NaCl solution are studied. The size and shape of the produced particles are characterized. It is concluded that the mechanism of polymerization is actually a combination of suspension and solution polymerization, and that the water content in the monomer phase is low enough to produce structurally homogeneous particles.
Novel poly(n‐butyl methacrylate)/titanium oxide alloys produced by te sol–gel process for titanium alkoxides
Authors: Mauritz K. A. , Jones C. K.
Published: April 2003

A method has been developed to cast novel organic/inorganic hybrid films from multicomponent solutions containing titanium alkoxides, poly(n‐butyl methacrylate), water, and isopropanol of prescribed compositions. The sol–gel reactions and controlled drying procedure yielded materials of mechanical integrity for which the multistep thermal degradation profile of the organic polymer has been significantly modified. A crystallization exotherm, presumably due to anatase formation, is seen for tetraethyl titanate‐derived films beyond the organic degradation temperature. The trend of mechanical tensile parameters with increasing Ti oxide content depicts progressive material strengthening. FT‐IR as well as the thermal and mechanical studies of these films suggest a highly unconnected and heterogeneous Ti oxide phase.
Vitrification and curing studies of a photopolymerizable semi‐interpenetrating polymer network. II
Authors: Fitzgerald J. J. , Landry C. J. T.
Published: April 2003

The photopolymerizable semi‐interpenetrating polymer network‐II being studied consists of a linear copolyester, a crosslinked network of multifunctional acrylate monomers and a very efficient photoinitiator system. Using both Raman and dynamic mechanical spectroscopy (DMS), it has been determined that the polymerizing network vitrifies after a very low level of crosslinking is attained. This results in a sample that has a Tg which is substantially lower than would be expected from knowledge of the values of Tg for the individual components of the blend. The extent of reaction and, therefore, the glass transition temperature can be increased by heating the sample during photopolymerization. In addition, the glass transition temperature of the network can be increased by thermally curing the sample after photopolymerization. It has been found that once the network has been fully cured, the glass transition temperature is much higher than would be predicted. This has been interpreted in terms of synergistic effects; conceivably, the acrylates form a tight matrix around the linear copolyester and effectively reduce the molecular mobility of the components. The results also show that the acrylates and the copolyester are not inherently miscible. However, if a sufficient concentration of acrylates is present, it is possible to prevent the copolyester from phase separating. Dynamic mechanical spectroscopy data do indicate that these semi‐inter‐penetrating polymer networks‐II (semi‐IPN‐II) samples are somewhat heterogeneous; however, there does not seem to be any gross phase separation. Transmission, electron microscopy (TEM) results show that the most fully cured sample has domains on the order of 50–250 Å associated with the copolyester phase.
Effects of resin and curing parameters on the degree of cure of resole phenolic resins and woodflour composites
Authors: So Solomon , Rudin Alfred
Published: April 2003

The degree of cure of various resole phenolic resins was assessed from their resistance to acetone extraction. Cured woodflour composites of resoles were also characterized by dynamic mechanical tests in linear viscoelastic behaviour regions. Acetone extraction is not a sensitive discriminator between highly cross‐linked resins. In addition, residual basic catalyst promotes aldol condensation reactions of acetone to produce materials that are absorbed in the phenolic resin so as to provide negative weight loss data on extraction. Despite its inaccuracies, however, this solvent resistance test is still useful as a go/no‐go specification technique. Dynamic mechanical tests were performed on molded resole/woodflour composites. This is a useful method for characterizing degree of cure and residual reactivity of the phenolic resin. Degree of cure increases with curing time, temperature and resin pH, with pH being the most important variable. Resins cured at pH's near neutral are linked by ether linkages rather than the more stable methylene bridges. The final degree of cure of woodflour composites depends heavily on the curing conditions (pH, time, temperature). It does not appear to be crucial how the initial resoles were made (i.e., catalyst, phenol/formaldehyde mole ratio or duration of the condensation reaction time) so long as the resoles have relatively high molecular weight. Curing should preferably be at temperatures below 180°C to minimize degradation of the polymer.
Influence of water on esterification reaction between terephthalic acid and ethylene glycol
Authors: Yamada Toshiro
Published: April 2003

Examples of simulation in the first reactor for the direct continuous esterification were shown to predict the effects of water added into the reactor (δ) on the reactions by a computer. From the simulation results, the followings were confirmed: Although the higher δ gives the worse results, i.e., the main reaction rates become lower, it brings about the better results, i.e., the side reactions of diethylene glycol (DEG) formation is suppressed; the clearing point where solid (undissolved) terephthalic acid begins not to exist in the reaction mixtures, β = 1, is the point of AV = 0.6 eq/kg, which coincides with the point obtained from the experimental observation, independently of reaction conditions.
Preparation, structure, and properties of copolyester‐ether elastic filaments
Authors: Richeson G. C. , Spruiell J. E.
Published: April 2003

Elastic filaments have been produced by melt spinning poly(tetramethylene terephthalate)/poly(tetramethylene ether glycol)‐terephthalate (PTMT/PTMEG‐T) copolymers of various hard segment contents (HSC). Some of these copolymers are difficult to spin because of their elastic nature and sluggish crystallization kinetics. Differential scanning calorimetry studies show that both the crystallization rate and temperature decrease as HSC decreases. When spinning into air, the filaments low in HSC do not crystallize on‐line and are too tacky and soft to be taken up with a conventional constant tension winder. The elastic nature of these filaments prevents them from being taken up at speeds high enough for “stress‐induced crystallization” to cause appreciable crystallization on‐line. Spinning into a water bath allows the filaments to be taken up without a “sticking” problem. The microstructure and mechanical properties of the water‐quenched filaments were found to be strongly dependent on composition and processing conditions. Small‐angle and wide‐angle x‐ray techniques (SAXS and WAXD) indicate that the hard segment domains are lamellar‐like crystallites which become preferentially oriented perpendicular to the fiber axis at high spin‐draw ratios. As HSC decreases, the lamellae become more widely spaced. High levels of crystalline orientation can be produced using the water quench technique without creating appreciable levels of amorphous orientation. These are desirable features for obtaining high elastic recovery. Birefringence results indicate that these filaments continue to crystallize for up to 10 minutes after spinning. The relative degree of phase separation (DPS) decreases as HSC increases, but the actual level of crystallinity exhibits a maximum with respect to composition. Not coincidentally, the filaments that reach the highest crystallinity are the easiest to spin. The modulus of these filaments depends primarily on HSC and DPS, while the tenacity and ultimate elongation depend more on the degree of orientation developed during spinning. Elastic recovery increases as HSC decreases and as crystalline orientation increases.
Fluorine‐containing photoreactive polyimide. II. Preparation and properties of self‐sensitized polyimide precursors
Authors: Omote Toshihiko , Guo‐jin  , Koseki Ken'ichi , Yamaoka Tsuguo
Published: April 2003

Two series of polyimide precursors that have benzophenone(BP) segments in addition to methacryloyl groups and perfluoromethyl groups in the main chain are described. These fluorinated polyimide precursors offered remarkable improvement in solubility in common organic solvents and self‐sensitivity at 365‐nm light (i‐line). It was also found that the sensitivity is extremely enhanced by the aid of a small amount of photoinitiators, and the effective initiators for sensitivity enhancement were different for each series of the precursors. These self‐sensitized polyimide precursors offered high resolution with good pattern profile of aspect ratio over 1.5. The temperatures for 10% weight loss of the imidized films were nearly 500°C from thermogravimetry analysis (TGA), indicating high thermal stability.
Melt transesterification of diphenyl carbonate with bisphenol a in a batch reactor
Authors: Hersh S. N. , Choi K. Y.
Published: April 2003

The kinetics of the melt transesterification of diphenyl carbonate with 4,4‐dihydroxydiphenyl‐2,2‐propane has been studied in a batch reactor with LiOH · H2O as a catalyst in the temperature range of 150–180°C. The third‐order forward and backward rate constants were determined experimentally and a linear dependence of the transesterification rate on the catalyst concentration was observed. The product oligomer concentration distribution has also been measured experimentally and estimated by the molecular species model which describes the progress of the melt transesterification.
Oxygen permeation in SBS‐g‐VP membrane and effect of facilitated oxygen carrier
Authors: Yang Jen‐ming , Hsiue Ging‐ho
Published: April 2003

The grafting of 4‐vinyl pyridine to styrene‐butadiene‐styrene triblock copolymer by radiationinduced graft copolymerization was studied. The membranes of various degrees of grafting were prepared by the solution casting method. The effect of grafting degree and operating temperature on membrane gas permeability were investigated. The effect of (N,N′‐disalicylideneethylenediamine)cobalt(II) [CoS] on oxygen permeation through the SBS‐g‐VP membrane containing 10 wt % CoS was also studied.
Investigations concerning dissolution and swelling of polymethacrylonitrile in organic liquids
Authors: Schlegel Leo , Schnabel Wolfram
Published: April 2003

The interaction of various liquids with polymethacrylonitrile (PMCN) was investigated with respect to their ability of acting as solvent or soaking agent. The extent of interaction with the polymer solvents were classified on the basis of the following characteristics—Category A liquids: UA, the rate of dissolution, is determined by Vrept, the rate of reptation. A swollen surface layer is formed during dissolution of polymer films. VA increases with decreasing Mw, the weight average molecular weight. Category B liquids: VA is determined by Vsolv, the rate of solvation. A swollen surface layer is not formed during dissolution of polymer films. VA is independent of Mw. Category C liquids: They are incapable of dissolving but capable of soaking PMCN. Penetration of polymer films is characterized by features typical of CASE II sorption—a sharp step‐wise penetrant profile proceeding with constant velocity Vsorp. Dissolution and soaking tests with X‐ray irradiated PMCN films carried out in category B or C liquids, respectively, revealed the importance of morphological properties regarding the rate of dissolution and sorption, respectively. The observed increase in VA and Vsorp with increasing exposure dose was concluded to be due to the radiation‐induced increase in free volume rather than to the decrease in Mw.
Analytical solution of reversible step growth polymerization in semibatch reactors
Authors: Kumar Anil , Khanna Ashok
Published: April 2003

We have developed an analytical solution of reversible step growth polymerization in semibatch reactor with condensation product flashing. We have shown that the MWD of the polymer formed has Flory distribution, unaffected by flashing of condensation product, if the feed to the reactor is either pure monomer or has most probable MWD. We have determined analytical expression for the time when the evaporation of condensation product starts. Assuming the vapor liquid equilibrium (VLE) is given by Raoult's law (as well as the Flory–Huggins relation) we have determined the number and weight average chain lengths. We have subsequently analyzed the polycondensation step of the formation of polyethylene terephthalate and determined the effect of temperature and pressure on the course of polymerization.
Structural features of cellulosic change in alkali‐treated jute stick: An infrared absorption study
Authors: Reddy S. S.
Published: April 2003

The cellulosic change has been discussed in terms of absorption ratio of certain infrared bands. It is shown that the absorption of O—H and C—H stretching frequencies decreases up to 25% alkali treatment and the absorption of β‐glucosidic band increases with increasing alkali strength in swelling. The anomalous behavior in the absorption of these bands at 18% alkali treatment might be due to partial mercerization. A new type of hydrogen bonding is proposed where C6 hydroxyl groups are involved in a bifurcated six‐membered hydrogen bonding system giving more crystalline nature to mixed lattice of cellulose. The O2 hydroxyl proton forms hydrogen bond with O3 of the same unit and with O'2H of its antiparallel chain. It is also noted that the presence of lignin has no significant effect on cellulosic transition.
An infrared spectroscopic study of molecular orientation in heat‐set poly(ethylene terephthalate) yarn using attenuated total reflection technique
Authors: Jain A. K. , Gupta V. B.
Published: April 2003

The attenuated total reflection (ATR) technique has been used to obtain infrared spectra of heat‐set poly(ethylene terephthalate) (PET) fibers. The trans and gauche content have been estimated from the absorbances of the trans band at 1342 cm−1, the gauche band at 1370 cm−1, and the internal standard band at 1410 cm−1. The trans orientation, as calculated from the dichroic ratios of the absorption bands at 1342, 972 and 846 cm−1, shows a decreasing trend with an increase in heat‐setting temperature. The overall molecular orientation, as calculated from the absorption bands at 1410 and 875 cm−1, also decreases slightly with an increase in heat‐setting temperature. The infrared data, in combination with X‐ray data, have been used to calculate the amorphous orientation factor. The ATR technique is shown to give quite representative values of the amorphous orientation factor.
Dissolution rates of poly(methyl methacrylate) in mixtures of nonsolvents
Authors: Groele R. J. , Krasicky P. D. , Chun S.‐W. , Sullivan J. , Rodriguez F.
Published: April 2003

As predicted by thermodynamic studies of polymer conformation, high molecular weight poly(methyl methacrylate) (PMMA) dissolves cleanly, and at a constant rate, in a 7 : 3 mixture of 1‐butanol and acetonitrile, although neither liquid is a solvent for PMMA by itself. Mixtures of other alcohols with acetonitrile also dissolve PMMA. When mixtures with the same fraction of acetonitrile are compared, methanol dissolves PMMA almost twice as fast, ethanol and hexanol at about the same rate, and 2‐propanol somewhat more slowly than the 1‐butanol mixture with acetonitrile. The measurements of dissolution rate were made using a laser interferometer at 20°C.
Rheology and morphology of polymer blends containing liquid‐crystalline component in melt and solid state
Authors: Kulichikhin V. G. , Vasil'Eva O. V. , Litvinov I. A. , Antipov E. M. , Parsamyan I. L. , Platé N. A.
Published: April 2003

The rheological properties of polymer blends containing polysulfone and LC polyester have been investigated in terms of the morphology and physical‐mechanical characteristics of the extrudates. The peculiarities of rheological behavior are connected with the morphology of stream, the latter being maintained also in solid extrudates. The reinforcement of an isotropic matrix by LC polymers as well as formation of an anisotropic surface layer leads to a specific change in the strength properties of compositions. A maximal increase in the strength and initial modulus was observed for blends containing not more than 10% LC polymer.
Pyridine‐catalyzed depolymerization of cellulose during carbanilation with phenylisocyanate in dimethylsulfoxide
Authors: Evans Robert , Wearne Ross H. , Wallis Adrian F. A.
Published: April 2003

Carbanilation reactions of cellulose samples (bleached cotton linters and Avicel) with phenylisocyanate in dimethylsulfoxide (DMSO) were carried out at 60°C in the presence of various pyridine derivatives. The molecular weight distributions of the resulting cellulose tricarbanilates (CTCs) were measured by high‐performance size exclusion chromatography. When pyridine or its derivatives were included in the reactions, the CTCs had reduced degree of polymerization (DP) values compared to those of CTCs prepared without the additives. The cellulose depolymerization was promoted by pyridines with electron‐donating substituents and was not favored by pyridines with electron‐withdrawing substituents nor with groups at positions ortho to the pyridine ring nitrogen atom. For the 3‐, 4‐, and 3,4‐ substituted pyridines, there was a linear relationship between log (weight‐average CTC DP) and the pKa (in water) of the pyridine derivative. For 2‐ and 2,6‐substituted pyridines, the DP–pKa relationships were different, probably because of steric effects of the different substituents ortho to the pyridine nitrogen atom. The optimum DMSO : pyridine solvent ratio for cellulose depolymerization during carbanilation in DMSO : pyridine mixtures was 3 : 1. All three components, phenylisocyanate, pyridine or its derivatives, and DMSO, are required for the depolymerization reaction. It is suggested that the depolymerization may be a consequence of cellulose oxidation by DMSO and/or cleavage of glucosidic bonds of partially carbanilated cellulose by reactions promoted by an enhanced solvent effect of DMSO.
Degradation mechanisms of poly(ethylene terephthalate) tire yarn
Authors: Sawada Shuzo , Kamiyama Kiyosuke , Ohgushi Shinichiro , Yabuki Kazayuki
Published: April 2003

In order to clarify the fatigue mechanism of PET tire cords in rubber focusing on chemical degradation, hydrolysis in saturated steam atmosphere, ammonolysis in ammonia gas, and the degradation of the cords embedded in rubber have been studied at high temperature conditions. It was found that the strength loss of polyester tire cords in rubber has linear correlation with the amount of chemically induced chain scissions mainly caused by hydrolysis catalyzed by amines.
Electron beam effects on polymers: V. Symmetric and asymmetric materials based on the controlled distribution of bis‐GMA into crosslinked nitrile rubber films prior to curing by electron beam radiation
Authors: Kim Ha‐Chul , El‐Naggar Abdel M. , Wilkes Garth L.
Published: April 2003

Two systems based on the controlled distribution of the methacrylic acid derivative of the diglycidyl ether of bisphenol‐A (bis‐GMA) into crosslinked acrylonitrile–butadiene co‐polymers, commonly called nitrile rubber (NBR), were prepared utilizing electron beam (EB) radiation. In the system called “symmetric,” the EB crosslinked NBR was swollen to equilibrium in solutions containing different concentrations of bis‐GMA. The swollen NBR film was then EB irradiated to different dosage levels. The other system, called “asymmetric” or “gradient,” was prepared by applying the solutions containing bis‐GMA to one surface of the EB crosslinked NBR film in a controlled time that was less than the time to achieve an equilibrium concentration across the thickness or “swelling” dimension. This asymmetrically swollen NBR film was then immediately EB irradiated using different dose levels. The prepared symmetric and asymmetric NBR systems were investigated by thermal and mechanical, as well as microscopic, analyses. The mechanical responses were shown to be strongly dependent on the bis‐GMA content in the NBR film and the type of preparation history. The dynamic mechanical spectra showed the presence of two transitions, indicating some level of phase separation that was supported by scanning electron microscopy of fracture surfaces for symmetric and asymmetric systems. The asymmetric distribution of the imbided (cured) monomer in the asymmetric system was confirmed by both FT‐IR and optical microscopy analyses.
Crosslinking structure of keratin: III. Rubberlike elasticity originating from non‐uniform structures of the swollen hair and wool fibers
Authors: Arai Kozo , Ma Guanghui , Hirata Taishi
Published: April 2003

Hair and wool fibers treated with an 11 M LiBr solution containing N‐ethylmaleimide showed typical rubberlike elasticity in a solution composed of equal volumes of 8 M LiBr and diethylene glycol monobutyl ether. Stress–strain relations of the swollen fibers were treated with a two‐phase structural model: a mechanically stable phase of higher crosslinked domains and a rubbery phase with lower crosslink density. Stress–strain curves were analyzed by applying non‐Gaussian chain statistics to the swollen keratin network, including microdomains, which act as reinforcing filler particles in rubber. Swollen hair showed about 2.3 times higher modulus than wool. It has been suggested that: (1) the difference in the modulus between the two keratins is attributable to the difference in the volume fraction of domains, and (2) the crosslink density of rubbery phase in hair is virtually identical to that in wool.
Chemical reactions in crosslinking of copolymers of ethylene and vinyltrimethoxy silane
Authors: Hjertberg T. , Palmlöf M. , Sultan B.‐Å.
Published: April 2003

The crosslinking reactions of a new type of polyethylene, an ethylene vinyltrimethoxy silane (EVS) copolymer, when reacted with water has been studied. Samples of EVS were treated in water at 90°C. The kinetics of the crosslinking was followed by measuring the gel content and by determination of the content of different structures (SiOCH3,SiOH, and SiOSi) using FT‐IR. The observations show that a maximum gel content of 70‐75% is obtained after 25 h treatment in water at 90°C. On the other hand, the absorption index for the crosslinks, SiOSi, continues to increase until about 100 h, i.e., more crosslinks seem to be formed without a simultaneous increase in gel content. Mechanical measurements showed decreased elongation at break even after very long treatments. Thermo‐oxidative degradation is, however, also responsible for the change in mechanical properties. For properly stabilized samples, the decrease in elongation leveled off after about 100 h of treatment. This indicates that the crosslinks formed after 25 h mainly should be within the already existing gel. The observed synergistic effect of crosslinking and thermo‐oxidative degradation emphasizes the importance of a proper stabilizing system.
Crosslinking reactions of ethylene vinyl silane copolymers at processing temperatures
Authors: Palmlöf M. , Hjertberg T. , Sultan B.‐Å.
Published: April 2003

The crosslinking reactions of ethylene vinyltrimethoxy silane (EVS) copolymers at processing temperatures have been studied. Samples were heated in inert atmosphere with or without water at 130–350°C. The crosslinking reactions were followed by determination of the gel content and by analyzing the structural changes using FT‐IR. As expected, no gel could be observed in pure EVS after treatment in nitrogen, whereas 30% was obtained if the nitrogen was presaturated with water. Addition of a catalyst, dibutyltindilaurate, increased the reaction rate considerably and a final gel content of 70–75% was obtained above 300°C. In contrast, neither water nor catalyst was needed for the formation of gel in a terpolymer of EVS containing butylacrylate as well. During heat treatment the acrylate units formed carboxylic acid, and blends of EVS and an ethylene acrylic acid (EAA) copolymer were therefore used as a model to study the reactions in detail. Despite absence of water these blends started to form gel at low temperatures, 150–200°C. This could mainly be related to internal production of water due to reaction between carboxylic groups leading to anhydride. Both cyclic and noncyclic anhydrides were detected by FT‐IR analysis. A larger amount of EAA in the EVS–EAA blend increased the rate of gel formation and decreased the onset temperature, but no corresponding change in the formation of noncyclic anhydride was observed. Another kind of crosslink, formed by reaction between carboxylic acid and silanol groups, can possibly be one explanation to this behavior.
Sulfonation of polyethylene membranes
Authors: Dimov A. , Islam M. A.
Published: April 2003

The polyethylene membranes are hydrophilized under the action of chlorosulfonic acid. Such a hydrophilized membrane shows much better water permeability in comparison with the unmodified one. The ion‐exchange capacity of the sulfonated membrane is taken as a measure for the hydrophilicity. The influences of the concentration of the sulfonating agent, temperature, and reaction time, on the ion‐exchange capacity and water permeability, are investigated. It is shown that the increase in the degree of sulfonation does not always lead to an increase in the water permeability of the membrane. A lower concentration of the sulfonating agent and a lower temperature are to be chosen, so that only the surface and the inner walls of the pores are sulfonated. Sulfonation in the bulk leads to the deterioration of mechanical properties of the membrane without having any contribution to the increase in the water permeability of the membrane.
Study on ketalization reaction of poly(vinyl alcohol) by ketones. IV. Reaction between poly(vinyl alcohol) and aliphatic ketones and behavior of polyvinylketal in water
Authors: Nakamura Naofumi
Published: April 2003

Ketalization reaction of poly(vinyl alcohol) (PVA) by aliphatic ketones, dimethylsulfoxide (DMSO) as solvent, under the presence of acidic catalyst, in homogeneous system was carried out and the synthesis of polyvinylketals were successfully performed. The equilibrium constant at 40°C is ca. 0.07 in the case of methyl n‐propyl ketone (nPK) and methyl n‐butyl ketone (nBK), but is ca. 0.05 in the case of methyl i‐propyl ketone (iPK) and ca. 0.01 in the case of methyl i‐butyl ketone (iBK) and methyl t‐butyl ketone (tBK), respectively. Moreover, the ketalization degree of polyvinylketal by iBK and tBK reached to only ca. 35 mol % as the maximum. It seems that these were due to steric hindrance of bulky side chain of ketones. But the heat of reaction is 7.5 kcal/mol in all aliphatic ketones, it seems to proceed the same ketalization reaction mechanism. Films prepared from the polyvinylketals were soaked in water and degree of swelling, solubility, and hydrolysis of films were measured. The reaction of film with water, in acidic side, at first the film swells, and then, as the deketalization reaction proceeds, the film dissolves in water. The dissolution time is controlled by the kind of ketones, ketalization degree, and pH of water which reveals that deketalization reaction proceeds proportional to proton concentration. It is more difficult to dissolve highly ketalized polyvinylketals obtained by propyl ketones and butyl ketones than that by acetone. The hydrolysis of polyvinylketal film proceeds in the order as follows: acetone > MEK > nPK > iPK ≒ nBK > iBK > tBK. This phenomenon seems to be affected by hydrophobicity of the film surface which depends upon the kind of the original ketones.
N‐acryloyl–N′‐phenylpiperazine as curing activator of unsaturated resins
Authors: Tanzi M. Cristina , Levi Marinella , Danusso Ferdinando
Published: April 2003

N‐acryloyl–N′‐phenylpiperazine and three of its homopolymers of different molecular weight are tested as low toxicity redox activators in the BPO curing of unsaturated polyester resins. Gel times and other time and temperature parameters drawn from standard exothermal curves are determined with two kinds of resin, at different bath temperatures and amounts of activator. The reciprocal of gel time follows a kinetic equation with average order 0.85 with respect to the activator, and an activation energy of 19 kcal/mol. With polymeric activators it is a simple decreasing exponential function of intrinsic viscosity. Correlations are observed for other parameters relative to the second, faster step of the curing process, in general less sensitive to the mentioned variables. The crosslinked resins show mechanical properties similar to those obtainable with dimethylaniline as activator.
Studies on the state of permeant in the membrane and its effect on pervaporation phenomena
Authors: Yoshikawa Masakazu , Matsuura Takeshi , Cooney David
Published: April 2003

Pervaporation experiments of pure water and 2‐propanol through poly‐dimethylsiloxane membranes were carried out in order to study the effect of the interaction between permeant and membrane material on pervaporation phenomena. From the effect of downstream pressure on the pervaporation rate, the saturation vapor pressure of water in the membrane was determined to be 2.799 × 103 Pa (21.0 mmHg), which is the same as the literature value, whereas that of 2‐propanol in the membrane was estimated to be 5.865 × 103 Pa (44.0 mm Hg), which is 8.53 × 102 Pa (6.4 mmHg) higher than that of pure 2‐propanol. In the differential scanning calorimetry analyses of permeants in the membrane, it was evident that the state of 2‐propanol in the polydimethylsiloxane membrane was different from that of bulk 2‐propanol. On the other hand, the state of water in the membrane was assigned to that of bulk water. Throughout the present study, it was observed that the interaction between permeant and membrane material plays an important role in determining pervaporation phenomena.
Weathering of polystyrene foam on exposure in air and in seawater
Authors: Andrady Anthony L. , Pegram Jan E.
Published: April 2003

Expanded extruded polystyrene foam was exposed outdoors in air and floating in seawater. The degradation of the materials was determined by ultraviolet spectroscopy, gel permeation chromatography, and measurement of yellowness, viscosity, and tensile properties. The samples underwent extensive yellowing, reduction in average molecular weight, and embrittlement in the exposed surface layer. Furthermore, the rate of deterioration was shown to be faster in seawater than in air, possibly due to the removal by the seawater of the outer protective yellow‐colored layer formed during early exposure to sunlight.
Free radicals of fibers treated with low temerature plasma
Authors: Chen Jie Rong
Published: April 2003

Cotton, linen, polynosic rayon, standard rayon, nylon 6, and poly(ethylene terephthalate) (PET) fibers were treated with low temperature plasmas of O2, N2, Ar, CF4, and CO. The relative free‐radical intensities obtained by ESR spectra increased in the following order: linen > cotton > polynosic rayon > standard rayon > nylon 6 ≈ PET and CF4 > CO > Ar > N2 > O2.
Preparation of a water‐permselective composite membrane by the concentrated emulsion method: Its swelling and permselectivity characteristics
Authors: Ruckenstein E. , Chen H. H.
Published: April 2003

A water‐permselective composite membrane was prepared by the concentrated emulsion polymerization method. A large volume fraction of an aqueous sodium acrylate solution was dispersed in a small amount of divinyl benzene. Each of the two phases contained a suitable initiator and the continuous phase contained an appropriate surfactant. The concentrated emulsion thus obtained has the appearance and behavior of a gel. The gel was sandwiched between tow glass plates and subjected to polymerization via heating at 45°C for 24 h. The resulting membrane was dried and further employed in several kinds of experiments. The swelling of the membrane in water depends on the pH of water and can be as large as 86. At low pH values, the swelling was very small. The permeation rate of a water‐ethanol mixture was in the range of 96–560 g/m2 h and decreased with increasing alcohol concentration and increasing poly(sodium acrylate) fraction in the membrane. The permselectivity varied between 32 and 235, increasing with increasing poly(sodium acrylate) fraction in the membrane and with increasing or decreasing ethanol concentration (depending upon the composition of the membrane). The activation energy for pervaporation varied between 6.58 and 8.14 kcal/mol, depending upon the composition of the feed. The permselectivity decreased slightly with increasing temperature.
The influence of charge density and steric factor of aminated chloromethyl polystyrene homologs in bilirubin adsorption
Authors: Raghavan D. , Shaligram A. M. , Deshpande D. D.
Published: April 2003

Bilirubin, a bile pigment, was studied for its extent of adsorption on substituted aminechloromethyl polystyrene by UV spectrophotometry. By performing simple displacement reactions on chloromethyl polystyrene with secondary and tertiary amines, the amount of charge density and steric factor on substituted nitrogen atom have been varied. Adsorption isotherms of bilirubin at 0°C by different amine–chloromethyl polystyrene homologs suggest the existence of electrostatic interaction of polymeric resin with bilirubin moiety. Results of adsorption of bilirubin to polymeric resin have shown that the extent of adsorption of bilirubin depends on the unit charge, and on the structure of the substituted amine–chloromethyl polystyrene. The effects of porosity of resin on bilirubin adsorption have also been discussed.
Synthesis and characterization of new ion‐exchange membranes
Authors: Elmidaoui A. , Sarraf T. , Gavach C. , Boutevin B.
Published: April 2003

The synthesis of grafted polymers of polyethylene (PE) with acrylic acid and N,N‐dimethylamino‐2 ethyl acrylate is performed in two steps. The first one needed the ozonization of powder of PE in well‐defined conditions to obtain an expected activation. The second one consisted in bulk grafting the two monomers by thermal decomposition of the above hydroperoxides and peroxides of the activated PE. After elimination of homoacrylated by selective solubilization, we obtained films by pressing the copolymers either alone or the mixture of the two copolymers to prepare the anion (or cation) exchange membrane and the amphoteric ion‐exchange membrane. The second part of the study deals with the physicochemical characterization of these membranes: thickness, exchange capacity, electrical resistance, transport number, and water content. These characteristics are given for various concentrations of equilibrating solutions and for various pH. The results show that we have perfectly corrected membranes that are competitive with the commercial ones.