bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural transitions in commercial cellulose systems
Authors: Khanchich O. A. , Loshadkin D. V. , Rozantsev E. G.
Published: July 2003

The problems of phase transitions in commercial cellulose systems during processing are considered. The formation of structures in regenerated cellulose from viscose solutions during precipitation in different regenerated baths and in highly concentrated solutions of cellulose in N‐methylmorpholin‐N‐oxide at different temperatures and shear deformations has been selected for this review. The difficulties in defining the type of structural ordering in these systems are demonstrated. Fractal analysis is used to study the structures. A close relationship between the characteristics of the structures and the fractal dimensions is elucidated. The prospects for the different methods of regulating structures in cellulose systems are discussed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 22–32, 2003
Miscibility studies of sodium alginate/poly(vinyl alcohol) blend in water by viscosity, ultrasonic, and refractive index methods
Authors: Ravi Prakash S. D. , Ramakrishna H. V. , Rai S. K. , Rajulu A. Varada
Published: July 2003

The miscibility of a sodium alginate/poly(vinyl alcohol) blend in water was studied by viscosity, ultrasonic velocity, and refractive index techniques at 30, 40, and 50°C. Using the viscosity data, interaction parameters μ and α were computed. These values revealed that the blend is miscible when the sodium alginate content is more than 50% in the blend. This was further confirmed by ultrasonic and refractive index methods. It was further observed that the temperature has only a marginal effect on the miscibility of this blend. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 33–39, 2003
Chemical and electrochemical synthesis of conducting graft copolymer of vinyl acetate with pyrrole and studies of its gas and vapor sensing
Authors: Hosseini S. Hossein , Entezami Ali A.
Published: July 2003

Copolymers in general exhibit physical and mechanical properties far different from those of homopolymers and different from those of blends of the same individual homopolymers. Pyrrole (Py) 3 was grafted onto a poly(vinyl acetate) (PVAc) backbone that contained the Py moiety within via chemical and electrochemical oxidative polymerization. Graft copolymer 4 was soluble with low Py amounts but became rapidly insoluble with increasing Py content due to the formation of long Py sequences. The maximum conductivity of films cast from the reaction mixture was 8.3 × 10−3 S/cm. The product 4 was characterized and studied in detail using elemental analysis, ATR, 1H‐NMR, UV‐visibility, gel permeation chromatography (GPC), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). Gas sensors based on conducting polymers that exhibit electrical conducting properties can be used as specific toxic gas and vapor detectors. We report here effects of conductance and mass changes onto a graft copolymer 4 after exposure to hydrogen halides, hydrogen cyanide, 1‐3‐5 trichloromethyl benzene (TCMB), methylbenzyl bromide (MBB), bromobenzyl cyanide (BBC), cyanogen chloride (CC), and cyanogen bromide (CB), using two techniques: a four‐point probe method and a X‐ray fluorescence (XRF) device, respectively. Increasing of ratio polypyrrole (PPy) in the graft copolymer 4 increase the sensing properties of this copolymer and decrease the solubility of it. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 40–48, 2003
Conducting polymer blends of polypyrrole with polyvinyl acetate, polystyrene, and polyvinyl chloride based toxic gas sensors
Authors: Hosseini S. Hossein , Entezami Ali A.
Published: July 2003

Blends of the conducting polymer, polypyrrole (PPy), and in the insulating host polymers, polyvinyl acetate (PVAc), polystyrene (PS), and polyvinyl chloride (PVC) resin, have been prepared chemically. Threshold conductivities occur at about 5% for PPy in blends with host polymers. The characterizations of these blends were done by FTIR, UV‐visible, differential scanning calorimetric (DSC), scanning electron microscopy (SEM), and thermal gravimetric analysis (TGA). The products of the blends have electrical conductivity comparable to PPy and mechanical properties similar to hosting polymers. The response mechanism of the conducting blends to a selection of gases and vapors was investigated using two techniques, measurement of conductance and mass changes using a four‐point probe method, and a X‐ray fluorescence (XRF) device, respectively. These responses of blends to toxic gases and vapors are more well explained. Prepared films were exposed to hydrogen halides (HCl, HBr, and HI), hydrogen cyanide, halogens (Cl2, Br2, and I2), monochloroacetic acid (MCAA), 1‐3‐5 trichloromethyl benzene (TCMB), methylbenzyl bromide (MBB), bromoacetone (BA), and cyanogen bromide (CB). The changes of conductivity of polymers frequently observed are partly due to one stage in the two‐stage sorption, perhaps involving the swelling of the polymer, then diffusion gases into polymer chains. The swelling of polymers is a slow process, therefore, preswelled polymer films tend to decrease the response times of blends with respect to gases. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 49–62, 2003
Adsorption of copper on specifically modified polyamide sorbent
Authors: Godjevargova T. , Mihova S.
Published: July 2003

A novel, specific sorbent based on polyamide covalently immobilized with dead yeast cells by glutaraldehyde was prepared and characterized. This sorbent exhibits a high capacity for metal complexation based on multifunctional groups of dead cells, as well as a good stability for reuse based on the crosslinking agent, glutaraldehyde. The Cu2+ sorption characteristics of the polyamide modified with immobilized dead cells were studied and compared to those of the polyamide chemically modified without cells. The adsorption capacity of specifically modified polyamide was about 19‐fold higher than the chemically modified polymer. The adsorption isotherms of Langmuir and Freundlich for the new specific sorbent were determined. The effect of pH, temperature and co‐ions (Zn2+, Pb2+, Co2+, Ca2+ and Mg2+) on the Cu2+ sorption capacity were studied. The effectiveness of heavy metal desorption and the coefficient of recovery of sorption ability were determined. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 80–85, 2003
Sorption characterization of poly(vinyl alcohol)/chitosan interpenetrating polymer network hydrogels
Authors: Kim Seon Jeong , Lee Ki Jung , Kim Sun I. , Lee Kyu Back , Park Yong Doo
Published: July 2003

Poly(vinyl alcohol) (PVA)/chitosan interpenetrating polymer networks (IPN) were prepared by UV irradiation. The water sorption behavior of the IPNs was measured at various temperatures and humidity levels. The water uptake of IPN13 is greater than that of other IPNs. Vapor sorption behavior is more affected by the density of water vapor than by hydrophilic properties with increasing temperature. Equilibrium water uptake increases as humidity increases, and the increase is more noticeable at high humidity. The sorption system of all IPNs is a relaxation‐controlled mechanism at a relative humidity (RH) of 90%, but it is a Fickian diffusion‐controlled mechanism when the RH is below 50%. With an increase in humidity, the diffusion coefficients were found to increase due to greater penetration of water into the IPNs. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 86–90, 2003
Electrical response characterization of chitosan/polyacrylonitrile hydrogel in NaCl solutions
Authors: Kim Seon Jeong , Shin Su Ryon , Lee Jang Han , Lee Sang Hoon , Kim Sun I.
Published: July 2003

A semi‐interpenetrating polymer network (semi‐IPN) hydrogel composed of chitosan and polyacrylonitrile (PAN) exhibited electrical‐sensitive behavior. The swelling behavior of the semi‐IPN was studied by immersion of the gels in aqueous NaCl solutions at various concentrations. The swelling ratio decreased with an increase in the concentration of the electrolyte solution. The stimulus response of the semi‐IPN hydrogel in electric fields was also investigated. When swollen, the semi‐IPN was placed between a pair of electrodes, and it exhibited bending behavior upon application of an electric field. The electro responsive behavior of the semi‐IPN was also affected by the electrolyte concentration of the external solution. The semi‐IPN also showed various degrees of increase in bending behavior depending on the electrical stimulus. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 91–96, 2003
Interrelation between dyeing and thermal properties of PET fibers
Authors: De Clerck K. , Rahier H. , Van Mele B. , Kiekens P.
Published: July 2003

The interrelation between dyeing and the thermal properties of micro and conventional poly(ethylene terephthalate) fibers is studied with conventional and modulated differential scanning calorimetry. X‐ray diffraction, density, and birefringence studies are used to confirm the obtained results. It is shown that three studied anthraquinone dyes, in contrast to three studied benzodifuranone dyes, act as plasticizers for the fibers. A comparison between fibers and partially crystallized bulk samples is made. The specific fiber morphology makes the fibers more susceptible to plasticization than are bulk samples. This ability of a dye to lower the glass transition of the fibers will influence the dye diffusion and this information is needed to optimize the dyeing process for a specific dye–fiber combination. Further, the presence of an anthraquinone dye in the fiber alters the melting endotherm by changing the stability of the original crystals. The onset of the melting and recrystallization process is lowered. Although still well above the dyeing temperature, this lowering may be critical for the dimensional stability of the fabrics during any subsequent high‐temperature process. A first investigation of the effect of variations in the thermal properties on the obtained color strength after dyeing is reported. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 105–114, 2003
Effects of vacuum ultraviolet on the structure and optical properties of poly(tetrafluoroethylene) films
Authors: Peng Guirong , Yang Dezhuang , Liu Jincheng , He Shiyu
Published: July 2003

The effects of vacuum ultraviolet (VUV) at wavelengths of 5–200 nm on the microscopic structure and optical properties of poly(tetrafluoroethylene) (PTFE) films were investigated. X‐ray photoelectron spectroscopy analysis showed that the C1s spectra changed from a single peak at 292.8 eV to multiplex peaks with binding energies of 284.6, 286.6, 288.6, 290.5, and 293.0 eV after VUV irradiation at 680 esh. With an increasing irradiation dose, the C1s peaks at 290.5 and 293.0 eV disappeared. After the PTFE film specimens irradiated at 1600 esh were sputtered with argon ions for 3 min, the C1s peaks at 290.5 and 293.0 eV appeared again, and the height of the peaks at 286.6 and 288.6 eV increased. The content of fluorine decreased after VUV irradiation. The content of fluorine in the film surface layer decreased significantly with the increase in the VUV intensity, but it did not change with the irradiation dose. Fourier transform infrared (FTIR) analysis results indicated that some conjugated bonds, such as FCCF, were formed during VUV irradiation, but no CH absorption bands were observed in the FTIR spectra; this indicated that the increase in the height of the C1s peak at 284.6 eV arose mainly from the carbon–carbon bonds, that is, from carbonification. The spectral transmittance of the PTFE film decreased gradually with an increasing VUV irradiation dose, and at a given dose, the lower the intensity was of the VUV irradiation, the greater the change was in the spectral transmittance. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 115–121, 2003
Graft copolymerization of acrylonitrile onto Cassia tora gum with ceric ammonium nitrate–nitric acid as a redox initiator
Authors: Sharma Brij Raj , Kumar Vineet , Soni P. L.
Published: July 2003

The graft copolymerization of acrylonitrile (AN) onto Cassia tora gum (CTG) was carried out in an aqueous medium with a ceric ammonium nitrate (CAN)–nitric acid initiation system. The percentage grafting and percentage grafting efficiency were determined as functions of the concentrations of CAN, nitric acid, AN, and CTG and the polymerization temperature and time. The results are discussed, and a reaction mechanism is proposed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 129–136, 2003
Computer simulation method for calculating concentration profiles in polyurethane/polystyrene interpenetrating polymer network membranes
Authors: Siddaramaiah  , Kumar H. , Roopa S. , Kendagannaswamy B. K. , Aminabhavi T. M.
Published: July 2003

Interpenetrating polymer networks (IPNs) of polyurethane (PU) and polystyrene (PS; 90/10 and 75/25) were synthesized by the condensation reaction of castor oil with methylene diisocyanate and styrene, with benzoyl peroxide as an initiator. The IPN membranes were characterized for physicomechanical, optical, and X‐ray diffraction properties. Computer‐simulated concentration profiles of aqueous salt solutions through PU/PS IPN membranes were generated with Fick's second‐order differential equation, and the results were examined in terms of diffusion anomalies. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 122–128, 2003
Soluble and crosslinked hydrophilic films based on compositions of poly(acrylic acid) and poly(2‐hydroxyethyl vinyl ether) for controlled drug release
Authors: Nurkeeva Z. S. , Mun G. A. , Khutoryanskiy V. V. , Bitekenova A. B. , Dzhusupbekova A. B. , Park K.
Published: July 2003

Soluble and crosslinked films based on compositions of poly(acrylic acid) and poly(2‐hydroxyethyl vinyl ether) were prepared. Solubility, morphology, mechanical characteristics, and swelling properties of the films were investigated. Potential applications of the polymer complex films in controlled drug delivery were also examined. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 137–142, 2003
Characterization and application of polypropylene films modified with stimuli‐sensitive copolymers with an Ar‐plasma postpolymerization technique
Authors: Sugiyama Kazuo , Shiraishi Kohei , Sono Kazuro
Published: July 2003

Surface‐modified polypropylene (PP) films with thermally and photochemically sensitive copolymers consisting of N‐(2‐hydroxypropyl)methacrylamide (HPMA) and 4‐(4‐methoxyphenylazo)phenyl methacrylate (MPAP), poly(HPMA‐co‐MPAP)‐g‐PP (abbreviated g‐PP) film, were prepared by graft copolymerization with an Ar‐plasma postpolymerization technique. The surfaces of the g‐PP films were characterized by means of X‐ray photoelectron spectroscopy; the percentage grafting of poly(HPMA‐co‐MPAP) with a number‐average molecular weight of 3.28 × 104 was 7.12%, and the molar ratio of HPMA–MPAH in the copolymer was 0.75:0.25. The stimuli‐sensitive adsorption of albumin and polystyrene microspheres on the g‐PP film was also measured. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 143–148, 2003
Preparation of ion‐exchange membranes by hydrolysis of radiation‐grafted polyethylene‐g‐polyacrylamide membranes
Authors: Gupta Bhuvanesh , Anjum Nishat
Published: July 2003

Polyethylene‐g‐polyacrylamide membranes were prepared by graft polymerization of acrylamide onto polyethylene films using a preirradiation method. The ion‐exchange membranes were obtained by the hydrolysis of grafted films so as to transform amide groups into carboxyl groups. The fraction of amide groups transformed into carboxyl groups was limited to ∼0.5. The characterization and thermal behavior of membranes with different degrees of grafting were evaluated by FTIR, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) measurements. The heat of fusion and the crystallinity of polyethylene decreased considerably in the hydrolyzed membranes depending on the degree of grafting. It was found that the grafting of acrylamide led to the reduction in crystallinity due to disruption of the crystallites (crystal defects) and dilution of the inherent crystallinity (dilution effect). The contribution of the hydrolysis step to the crystallinity decrease was negligible. The thermal stability of the membranes as obtained from TGA showed considerable enhancement after hydrolysis. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 149–154, 2003
Introduction of molecular spacers between the crosslinks of a cellulose‐based superabsorbent hydrogel: Effects on the equilibrium sorption properties
Authors: Sannino A. , Maffezzoli A. , Nicolais L.
Published: July 2003

The possibility to modulate cellulose‐based hydrogel sorption properties through the insertion of molecular spacers between the crosslinks was investigated. Starting polymers were the sodium salt of carboxymethyl cellulose, a polyelectrolyte cellulose derivative, and hydroxyethyl cellulose, a nonpolyelectrolyte derivative. Poly(ethylene glycol) with various molecular weights was linked by its free ends at two divinyl sulfone (DVS) crosslinker molecules, to increase the average distance between two crosslinking sites and thus to act as a spacer. Both the effect of the concentration and the molecular weight of the spacer on the hydrogel final sorption properties in water and water solutions were investigated. The presence of the spacer allowed us also to perform hydrogel synthesis with higher concentrations of cellulose in the reactive mixture, and the effect of the polymer concentration in the batch was analyzed. Hydrogels obtained in the presence of spacers displayed significantly higher equilibrium sorption properties than those of the ones obtained without spacers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 168–174, 2003
Morphology and mechanical properties of polypropylene and poly(ethylene‐co‐methyl acrylate) blends
Authors: Genovese A. , Shanks R. A.
Published: July 2003

The morphology and mechanical properties of isotactic polypropylene (iPP) and poly(ethylene‐co‐methyl acrylate) (EMA) blends were investigated. Various EMA copolymers with different methyl acrylate (MA) comonomer content were used. iPP and EMA formed immiscible blends over the composition range studied. The crystallization and melting reflected that of the individual components and the crystallinity was not greatly affected. The size of the iPP crystals was larger in the blends than those of pure iPP, indicating that EMA may have reduced the nucleation density of the iPP; however, the growth rate of the iPP crystals was found to remain constant. The tensile elongation at break was greatly increased by the presence of EMA, although the modulus remained approximately constant until the EMA composition was greater than 20%. EMA with a 9.0% MA content provided the optimum effect on the mechanical properties of the blends. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 175–185, 2003
Effect of high‐temperature annealing on the elastoplastic response of isotactic polypropylene in loading–unloading tests
Authors: Drozdov A. D. , de C. Christiansen J.
Published: July 2003

A series of uniaxial tensile loading–unloading tests is performed on isotactic polypropylene at room temperature. Prior to mechanical testing, injection‐molded specimens are annealed for 24 h at temperatures T = 145, 150, 155, 158, 160, 163, and 165°C, which cover the entire region of high‐temperature annealing temperatures. A constitutive model is developed for the elastoplastic behavior of a semicrystalline polymer at small strains. The stress–strain relations are determined by six adjustable parameters that are found by matching observations in cyclic tests. Fair agreement is demonstrated between the experimental data and the results of numerical simulation. It is shown that all material constants are affected by the annealing temperature, which is explained by changes in the crystalline morphology driven by thermal treatment. Some of the adjustable parameters experience finite jumps in the vicinity of the critical temperature Tc = 159°C. These jumps are attributed to the α2 → α2′ phase transformation. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 186–196, 2003
Polymerization of maleic anhydride–modified plant oils with polyols
Authors: Eren Tarik , Küsefoğlu Selim H. , Wool Richard
Published: July 2003

In this study soybean oil triglycerides were reacted with maleic anhydride in an ene reaction to introduce more than two maleate residues per triglycerides. The maleinized soybean oil (SOMA) was then polymerized with diols to the half‐ester stage only. Two different types of alcohols was used in this work: (1) short‐chain polyhydroxy linear or cyclic alcohols having 2, 3, 4, or 6 hydroxyl groups; and (2) long‐chain dihydroxy alcohols. The aim was to determine the effect of functionality and chain length by choosing alcohols with increasing number of hydroxyl groups and different chain lengths. The reaction of alcohols with anhydride functionalized soybean oil to give a polymeric half‐ester is a reaction that proceeds without the formation of byproducts and is different from complete polyesterification of maleinized oils, which are well known. To improve the reaction yields, different catalysts and different reaction conditions were examined. The structural analysis of the products was done with 1H‐NMR and IR spectroscopy. All of the new polymers obtained were resilient and soft rubbers at room temperature. Castor oil polymer mixed with 60% CaCO3 and 12% cork powder gave a resilient and nontacky linoleum composition. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 197–202, 2003
Upgrading melamine–urea–formaldehyde polycondensation resins with buffering additives. I. The effect of hexamine sulfate and its limits
Authors: Kamoun C. , Pizzi A. , Zanetti M.
Published: July 2003

Iminoamino methylene base intermediates obtained by the decomposition of hexamethylenetetramine (hexamine) stabilized by the presence of strong anions such as SO and HSO, or hexamine sulfate, were shown to markedly improve the water and weather resistance of hardened melamine–urea–formaldehyde (MUF) resins used as wood adhesives and of the wet internal bond strength performance of wood boards bonded with them. The effect was shown to be induced by very small amounts, between 1 and 5 wt % of this material on resin solid content. This strong effect allowed the use of MUF resins of much lower melamine content and also provided good performance of the bonded joints. Because the main effect was also present at the smaller proportion of hexamine as hexamine sulfate, it was not due at all to any increase in the molar ratio of the resin as a consequence of hexamine sulfate addition. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 203–214, 2003
Upgrading of MUF polycondensation resins by buffering additives. II. Hexamine sulfate mechanisms and alternate buffers
Authors: Zanetti M. , Pizzi A.
Published: July 2003

Iminoamino methylene bases intermediates are obtained by the decomposition of hexamethylenetetramine (hexamine). These are stabilized by the presence of strong anions such as SO and HSO, that is, “hexamine sulfate.” The effect of hexamine sulfate was closely linked to the strong buffering action it has on MUF resins. Its role is mainly to induce regularity of the reaction and the stability of conditions during resin networking, due to the buffer. Shifting of the polycondensation ⇌ degradation equilibrium to the left appeared to be the determinant factor. This was a consequence of maintaining a higher, constant pH during curing, due to the buffer action. The modulus of elasticity (MOE) increases the curves of hexamine sulfate‐catalyzed MUF resins, confirming this trend. The resins are faster curing than when catalyzed by ammonium sulfate. The effect is valid within the narrow buffering range of pH's used for resin hardening. Polycondensation is far too slow to occur at a much higher pH, and degradation is, instead, more predominant at much lower pH's. The network formed is then more crosslinked and less tainted by degradation when curing occurs within the correct pH range. The result is a much better performance of the wood board after water attack. The effects induced by hexamine sulfate effects are of longer duration than those of other potential buffers. This is due to the hexamine sulfate heat stability under standard hot curing conditions of the resin. Alternate systems were found and shown to have a comparable effect. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 215–226, 2003
Synthesis of water‐soluble syndiotacticity‐rich low molecular weight poly(vinyl alcohol) by solution copolymerization of vinyl pivalate/vinyl acetate in tetrahydrofuran and saponification
Authors: Lyoo Won Seok , Yeum Jeong Hyun , Ghim Han Do , Lee Joon‐Seok , Ji Byung Chul , Yoon Nam Sik , Ha Jae Boo , Lee Jinwon
Published: July 2003

Syndiotacticity‐rich low molecular weight poly(vinyl alcohol) (PVA) was synthesized by solution copolymerization of vinyl pivalate (VPi) and vinyl acetate (VAc) in tetrahydrofuran (THF) at low temperature using 2,2′‐azobis(2,4‐dimethylvaleronitrile) (ADMVN) as an initiator and successive saponification of copoly(VPi/VAc). Effects of initiator and monomer concentrations and polymerization temperature on the polymerization behavior and molecular structure of PVA prepared were investigated. The polymerization rate of VPi and VAc in THF was proportional to the 0.96 power of ADMVN concentration, indicating the heterogeneous nature of THF polymerization. Low‐temperature solution copolymerization of VPi and VAc in THF by adopting ADMVN proved to be successful in obtaining water‐soluble PVA with number‐average degree of polymerization of 180–360, syndiotactic diad content of 56–58%, and ultimate conversion of VPi and VAc into copoly(VPi/VAc) of over 80%, respectively. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 227–232, 2003
Thermal and mechanical properties of microwave‐ and heat‐cured poly(methyl methacrylate) used as dental base material
Authors: Usanmaz Ali , Ateş Julide , Doğan Arife
Published: July 2003

The thermal and mechanical properties of dental base materials cured by microwave and conventional heat methods were studied. The commercial dental base poly(methyl metacrylate) (PMMA) powder and liquid were mixed in a 3/1 ratio. They were polymerized by a peroxy catalyst at 65°C, then cured with a boiling water temperature and microwave radiation for periods of 5, 10, 15, 20, 25, 30, and 35 min for heat curing and 1, 2, 3, 5, and 7 min for microwave radiation. The microwave radiation outputs used were 500 and 700 W. The products of 5‐min heat curing and 1‐, 2‐, and 7‐min microwave curing were soluble in chloroform. All the others were partially soluble. The viscosity‐average molecular weights of the soluble samples were about 1 × 106. The thermal properties of the polymer samples were studied by differential scanning calorimetry (DSC). For the samples that were not cured completely, broad exothermic peaks at around 125°C were obtained in the DSC thermograms. The glass‐transition temperatures for completely cured samples were 110–120°C. The mechanical properties of the samples were determined from tensile and three‐point bending tests. The elastic modulus was highest for samples obtained by the conventional method with a 30‐min curing period. However, the bending modulus was highest for 7‐min cured samples in a 700‐W microwave. The mechanical strengths of the 700‐W output were higher than those at 500 W. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 251–256, 2003
In situ epoxidized natural rubber: Improved oil resistance of natural rubber
Authors: Tanrattanakul Varaporn , Wattanathai Boonsit , Tiangjunya Adul , Muhamud Putsadee
Published: July 2003

This study sought to synthesize an in situ epoxidized natural rubber (NR) from 20% dry rubber content latex stabilized by nonionic surfactant, 5 phr of Terric 16A16, in the presence of hydrogen peroxide and formic acid at the temperature of 50°C. The molar ratios of H2O2 and HCOOH to isoprene unit were equal, 0.75 : 0.75. Reaction was carried out for 3 to 8 h. This reaction yielded products of various epoxide contents depending on reaction time. Based on DSC characterization, epoxide contents of the in situ epoxidized natural rubbers (ENRs) were about 22–39 mol %. Tensile properties and tear resistance of the in situ ENRs were equal to, or better than, those of NR and commercial ENRs. The in situ epoxidation improved resistance to petroleum ether, but not to toluene. Changes in volume and weight of specimens immersed in ASTM no. 3 oil and automobile oils (various trade names: Shell engine oil, Shell gear oil, and Toyota motor oil) exhibited significant decrease after epoxidation, except in Shell brake fluid. Similar results were obtained from tensile testing of the oil‐immersed specimens. Tensile strength and elongation at break of the in situ ENRs were much higher than those of NR after immersion in those oils at room temperature for 7 days, except the immersion in brake fluid. Improved oil resistance of the in situ ENRs under severe condition was obtained in gear oil. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 261–269, 2003
UV‐curable powder coatings based on dendritic poly(ether‐amide)
Authors: Wei Huanyu , Liang Hongbo , Zou Jianhua , Shi Wenfang
Published: July 2003

Semi‐crystalline dendritic poly(ether‐amide)s were synthesized by modifying hydroxyl end‐groups of dendritic poly(ether‐amide) with aromatic urethane acrylate and octadetyl isocyanate. The ratio of these modifiers can adjust the final properties of products to fulfill the requirements of UV‐curable powder coatings. These UV‐curable semi‐crystalline dendritic poly(ether‐amide)s have a Tg in the range of 41–45°C and a Tm of around 120°C. Their thermal behavior and semi‐crystalline properties were studied by DSC and XRD. The photopolymerization kinetics was investigated by Photo‐DSC. The residual unsaturation, thermal stability, and hardness of the UV‐cured films were also studied. The obtained results show that these semi‐crystalline dentritic poly(ether‐amide)s may be used as prepolymers in UV‐curable powder coating systems. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 287–291, 2003
Studies on phase separation rate in porous polyimide membrane formation by immersion precipitation
Authors: Matsuyama Hideto , Nakagawa Keizo , Maki Taisuke , Teramoto Masaaki
Published: July 2003

Phase separation rate during porous membrane formation by immersion precipitation was investigated by light scattering in a polyimide/N‐Methylpyrrolidone (NMP)/water system. In the light scattering measurement, plots of scattered intensity against scattered angle showed maxima in all cases, which indicated that phase separation occurred by a spinodal decomposition (SD). Characteristic properties of the early stage of SD, such as an apparent diffusion coefficient Dapp and an interphase periodic distance Λ, were obtained. The growth process of Λ was also followed by light scattering. The growth rate had the same tendency as Dapp when water content in the nonsolvent bath and the polymer concentration in the cast solution were changed. The pore size of the final membrane increased with decreasing water content, which was opposite to the tendency of Λ growth rate. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 292–296, 2003
Controlled degradation of cured natural rubber by encapsulated benzophenone as a photosensitizer
Authors: Riyajan Sa‐Ad , Sakdapipanich Jitladda Tangpakdee , Tanaka Yasuyuki
Published: July 2003

The photodegradation of raw natural rubber and natural rubber compound film were studied using an artificial solar energy simulator. The properties of degraded rubber sheets containing benzophenone (BP) were determined by solution viscosity, 1H‐NMR, and FTIR analyses. In the case of rubber compounds containing BP, the changes of tensile strength and crosslinking density were determined. It was found that BP could amply accelerate the photodegradation of rubber. To control the release rate of BP, it was necessary to encapsulate BP with urea–formaldehyde as a matrix. The encapsulated BP or capsule was formed by an interfacial polycondensation reaction between formaldehyde and urea. The kinetic of release rate of BP from urea–formaldehyde capsule was markedly observed within 15 days of release time; after that the rate of BP released from urea–formaldehyde microcapsule was very slow. At the same concentration of BP, the degradation rate of rubber compound by adding BP directly was faster than that of the rubber containing encapsulated BP. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 297–305, 2003
A pheromonotropic peptide of Helicoverpa zea, with melanizing activity, interaction with PBAN, and distribution of immunoreactivity
Authors: Raina Ashok K. , Kingan Timothy G. , Kochansky Jan P.
Published: July 2003

The sequence of an 18–amino acid residue peptide was deduced from the gene encoding PBAN and other peptides with common C‐termini in Helicoverpa zea. The peptide caused melanization in larvae and pheromone production in females of H. zea, and was designated pheromonotropic melanizing peptide (Hez‐PMP). The peptide has a 83% sequence homology with a pheromonotropic peptide isolated from Pseudaletia separata. PMP caused melanization and mortality when injected into larvae just before molting. Whereas intense melanization was caused with a dose of 1,000 pmol, peak mortality occurred at 100 pmol, with 50% of larvae dying within 48 h after injection. Pheromonotropic activity of PMP was dose dependent. Co‐injection of Hez‐PMP and Hez‐PBAN into a female resulted in suppression of the pheromonotropic effect of PBAN. Whole‐mount immunocytochemical studies revealed PMP‐like immunoreactivity in frontal ganglion, subesophageal, thoracic, and abdominal ganglia as well as the esophageal nerve. Arch. Insect Biochem. Physiol. 53:147–157, 2003. Published 2003 Wiley‐Liss, Inc.
Kinases, intracellular calcium, and apolipophorin‐III influence the adhesion of larval hemocytes of the lepidopterous insect, Galleria mellonella
Authors: Zakarian Robert J. , Dunphy Gary B. , Rau Manfred E. , Albert Paul J.
Published: July 2003

Based on the results from the use of selective inhibitors and activators, active protein kinase A, protein tyrosine kinase, and protein kinase C (PKC) isoforms decreased the adhesion of larval Galleria mellonella hemocytes to glass slides. The protein kinase A inhibitor at all concentrations increased granular cell adhesion only whereas protein tyrosine kinase elevated both granular and plasmatocyte attachment at the lowest concentration. Active, Ca2+‐ and lipid‐dependent PKC isoforms limited plasmatocyte and granular cell adhesion whereas PKC that was inhibited by selected compounds (with differed modes of PKC inhibition) enhanced hemocyte attachment. The granular cells were more sensitive to the PKC inhibitors than were plasmatocytes. Phospholipase C and its diacylglyceride product were necessary to reduce hemocyte adhesion and maintain PKC activity. Extracellular Ca2+, possibly transported through L‐channels, was required for plasmatocyte attachment. In contrast, lowering the levels of cytosolic Ca2+ was associated with decreased PKC activity and was required for hemocyte adhesion. Arch. Insect Biochem. Physiol. 53:158–171, 2003. © 2003 Wiley‐Liss, Inc.
Antisense inhibition of neuronal nicotinic receptors in the tobacco‐feeding insect, Manduca sexta
Authors: Fickbohm David , Trimmer Barry Andrew
Published: July 2003

Acetylcholine is the predominant excitatory transmitter in the insect central nervous system with many of its effects mediated by nicotinic acetylcholine receptors. These receptors are present at very high density and are structurally heterogeneous, although little is known about functional distinctions between them. An interesting system for examining these receptors is the larval stage of Manduca sexta, a nicotine‐resistant tobacco‐feeding insect. The nicotinic responses of cultured neurons were found to be blocked by mecamylamine and curare but highly resistant to α‐bungarotoxin. The responses were also unaffected by the reducing agent dithiothreitol and the alkylating agent bromoacetylcholine suggesting that the α‐subunit dicysteine agonist binding site is protected. To begin determining the functional roles of different subunits in these receptors, cultured neurons were treated with oligonucleotides based on the gene sequence of the alpha subunit, MARA1. Antisense DNA caused a significant downward shift in the amplitude distribution of nicotinic responses compared to sense or reverse antisense treatments. These treatments did not affect currents mediated by the application of GABA. The reduction in the nicotinic depolarization and inward currents did not affect the rate of current onset or recovery, suggesting that antisense MARA1 causes a partial block of all nicotinic responses in these neurons. These results demonstrate that receptor gene expression in insect neurons can be manipulated in a sequence‐specific manner by antisense treatment and they provide evidence that MARA1 is important for normal nicotinic responses in Manduca. Arch. Insect Biochem. Physiol. 53:172–185, 2003. © 2003 Wiley‐Liss, Inc.
Effect of silkworm hemolymph on N‐linked glycosylation in two Trichoplusia ni insect cell lines
Authors: Joosten Christoph E. , Park Tai Hyun , Shuler Michael L.
Published: July 2003

A recombinant N‐linked glycoprotein, secreted human placental alkaline phosphatase (SEAP), was produced in two Trichoplusia ni insect cell lines using the baculovirus expression vector. Silkworm hemolymph (SH) was added to TNMFH + 10% fetal bovine serum (FBS) medium to a concentration of 2.5% or 5%, and SEAP production and glycosylation in the presence of SH were compared with controls devoid of hemolymph. Growing Tn‐4s cells in 5% SH‐supplemented medium required progressive adaptation of the cells to SH, and adapted cells had a SEAP specific yield decreased by 2.5‐fold compared with control cells not exposed to SH. Although SEAP produced in the control possessed little complex glycosylation (<1%), SEAP produced by SH‐adapted cells in the presence of 5% SH possessed 8.7% sialylated structures, as well as unusual, asialylated, agalactosylated structures with a high degree of polymerization (DP). On the basis of enzymatic and mass‐spectrometric analyses, we propose that these structures are glucosylated, high‐mannose oligosaccharides. SEAP was also produced by Tn‐4s cells without adaptation to SH when SH was added just prior to baculovirus infection, but SEAP specific yield was adversely affected (approximately fourfold reduction compared with control devoid of hemolymph), and glycosylation of SEAP produced under these conditions was characterized by large amounts of high‐mannose and high‐DP structures and an absence of complex structures. Similarly, Tn5B1‐4 cells that were not adapted to SH had a SEAP specific yield reduced by approximately fivefold in SH‐containing medium; however, these cells were able to produce 13.5% sialylated SEAP in the presence of 2.5% SH, whereas complex structures were not produced in the absence of SH. We propose that SH improves glycosylation either directly or indirectly by decreasing SEAP specific yield. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 83: 695–705, 2003.
On‐line monitoring of Phaffia rhodozyma fed‐batch process with in situ dispersive raman spectroscopy
Authors: Cannizzaro Christopher , Rhiel Martin , Marison Ian , von Stockar Urs
Published: July 2003

Since the yeast Phaffia rhodozyma was first described some 35 years ago, there has been significant interest in the development of commercial processes to exploit its ability to produce carotenoids (∼80% astaxanthin). However, the optimal conditions for carotenoid production are not well understood. A key limitation has been the lack of an appropriate sensor for on‐line carotenoid quantification. In this study, an in situ Raman spectroscopy probe was used to monitor intracellular carotenoid production for three consecutive P. rhodozyma fed‐batch experiments. Raman spectroscopy is particularly well suited to the study of carotenoids due to a resonance effect, which greatly enhances the intensity of the three fundamental carotenoid bands, ν1 (1513 cm−1, CC stretch), ν2 (1154 cm−1, C—C stretch), and ν3 (1003 cm−1, CH3 rock). For all three cultures, the peak height of these bands was linearly correlated with intracellular carotenoid content (1 to 45 mg/L) to a precision of better than 5%, and the correlation from one experiment was directly applicable to others. ©2003 Wiley Periodicals, Inc. Biotechnol Bioeng 83: 668–680, 2003.
Scalable inoculation strategies for microcarrier‐based animal cell bioprocesses
Authors: Dürrschmid M. , Landauer K. , Simic G. , Blüml G. , Doblhoff‐Dier O.
Published: July 2003

Scalability is a major demand for high‐yield, stable bioprocess systems in animal cell culture–based biopharmaceutical production. Increased yields can be achieved through high‐density cell culture, such as in the combination of microcarrier and fluidized bed bioreactor technology. To minimize inocula volume in industrial applications of fluidized bed fermentation systems, it is crucial to increase the bed volume in the reactor during the fermentation process. We tested scale‐up strategy for the production of recombinant human arylsulfatase B (ASB) enzyme used in enzyme replacement therapy in patients afflicted with mucopolysaccharidosis type VI (MPS VI). This enzyme was derived from Chinese hamster ovary (CHO) cells cultivated as adherent cell culture on Cytoline macroporous microcarriers (Amersham Biosciences, Uppsala, Sweden) using a Cytopilot Mini fluidized bed bioreactor (FBR; Amersham Biosciences, Vogelbusch, Austria). Both 1:2 expansion (herein referred to as the addition of fresh, not‐yet‐colonized microcarriers) and 1:6 expansion of the carrier bed were performed successfully; the cells restarted to proliferate for colonizing these newly added carriers; and the stability of the culture was not negatively affected. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 83: 681–686, 2003.
Expression of galP and glk in a Escherichia coli PTS mutant restores glucose transport and increases glycolytic flux to fermentation products
Authors: Hernández‐Montalvo Verónica , Martínez Alfredo , Hernández‐Chavez Georgina , Bolivar Francisco , Valle Fernando , Gosset Guillermo
Published: July 2003

In Escherichia coli, the uptake and phosphorylation of glucose is carried out mainly by the phosphotransferase system (PTS). Despite the efficiency of glucose transport by PTS, the required consumption of 1 mol of phosphoenolpyruvate (PEP) for each mol of internalized glucose represents a drawback for some biotechnological applications where PEP is a precursor of the desired product. For this reason, there is considerable interest in the generation of strains that can transport glucose efficiently by a non‐PTS mechanism. The purpose of this work was to study the effect of different gene expression levels, of galactose permease (GalP) and glucokinase (Glk), on glucose internalization and phosphorylation in a E. coli PTS− strain. The W3110 PTS−, designated VH32, showed limited growth on glucose with a specific growth rate (μ) of 0.03 h−1. A low copy plasmid family was constructed containing E. coli galP and glk genes, individually or combined, under the control of a trc‐derived promoter set. This plasmid family was used to transform the VH32 strain, each plasmid having different levels of expression of galP and glk. Experiments in minimal medium with glucose showed that expression of only galP under the control of a wild‐type trc promoter resulted in a μ of 0.55 h−1, corresponding to 89% of the μ measured for W3110 (0.62 h−1). In contrast, no increase in specific growth rate (μ) was observed in VH32 with a plasmid expressing only glk from the same promoter. Strains transformed with part of the plasmid family, containing both galP and glk genes, showed a μ value similar to that of W3110. Fermentor experiments with the VH32 strain harboring plasmids pv1Glk1GalP, pv4Glk5GalP, and pv5Glk5GalP showed that specific acetate productivity was twofold higher than in W3110. Introduction of plasmid pLOI1594, coding for pyruvate decarboxylase and alcohol dehydrogenase from Zymomonas mobilis, to strain VH32 carrying one of the plasmids with galP and glk caused a twofold increase in ethanol productivity over strain W3110, also containing pLOI1594. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 83: 687–694, 2003.
Effects of β‐cyclodextrin–dextran polymer on stability properties of trypsin
Authors: Fernández Michael , Villalonga Maria L. , Caballero Julio , Fragoso Alex , Cao Roberto , Villalonga Reynaldo
Published: July 2003

Dextran modified with the mono‐6‐pentylene‐diamino‐6‐deoxy‐β‐cyclodextrin derivative was evaluated as a thermoprotectant additive for trypsin. The optimum temperature for trypsin activity was increased by 7°C in the presence of this polymer. The enzyme thermostability was increased from 48.5 to 64°C over 10 min of incubation, and the activation free energy of thermoinactivation at 50°C was increased by 4.1 kJ/mol in the presence of the additive. Trypsin was 6‐fold more resistant to autolytic inactivation at alkaline pH in the presence of the polymer. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 83: 743–747, 2003.
Simultaneous nitrification and denitrification using stored substrate (phb) as the electron donor in an SBR
Authors: Third Katie A. , Burnett Natalie , Cord‐Ruwisch Ralf
Published: July 2003

The potential for PHB (poly‐β‐hydroxybutyrate) to serve as the electron donor for effective simultaneous nitrification and denitrification (SND) was investigated in a 2‐L sequencing batch reactor (SBR) using a mixed culture and acetate as the organic substrate. During the feast period (i.e., acetate present), heterotrophic respiration activity was high and nitrification was prevented due to the inability of nitrifying bacteria to compete with heterotrophs for oxygen. Once acetate was depleted the oxidation rate of PHB was up to 6 times slower than that of soluble acetate and nitrification could proceed due to the decreased competition for oxygen. The slow nature of PHB degradation meant that it was an effective substrate for SND, as it was oxidised at a similar rate to ammonium and was therefore available for SND throughout the entire aerobic period. The percentage of nitrogen removed via SND increased at lower DO concentrations during the famine period, with up to 78% SND achieved at a DO concentration of 0.5 mg L−1. However, the increased percentage of SND at a low DO concentration was compromised by a 2‐times slower rate of nitrogen removal. A moderate DO concentration of 1 mg L−1 was optimal for both SND efficiency (61%) and rate (4.4 mmol N. Cmol X−1 · h−1). Electron flux analysis showed that the period of highest SND activity occurred during the first hour of the aerobic famine period, when the specific oxygen uptake rate (SOUR) was highest. It is postulated that a high SOUR due to NH and PHB oxidation decreases oxygen penetration into the floc, creating larger zones for anoxic denitrification. The accumulation of nitrate towards the end of the SND period showed that SND was finally limited by the rate of denitrification. As PHB degradation was found to follow first‐order kinetics (dfPHB/dt = −0.19 · fPHB), higher PHB concentrations would be expected to drive SND faster by increasing the availability rate of reducing power and reducing penetration of oxygen into the floc, due to the corresponding increased SOUR. Process control techniques to accumulate higher internal PHB concentrations to improve PHB‐driven SND are discussed. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 83: 706–720, 2003.