bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermal analysis of curing process of epoxy prepreg
Authors: Sun Liangfeng , Pang Su‐Seng , Sterling Arthur M. , Negulescu Ioan I. , Stubblefield Michael A.
Published: August 2002

The curing process of epoxy prepreg was studied by means of differential scanning calorimetry analysis. The dynamic, isothermal, and combinations of dynamic and isothermal measurements were done over selected temperature ranges and isothermal cure temperatures. The heats of reaction for dynamic and isothermal cure were determined. The results show that the heat of the isothermal‐cure reaction increased with the increment of temperature. The degree of cure was calculated from the heat of the isothermal‐cure reaction. The complete cure reaction could be achieved at 220°C within a very short cure time. The changes of cure rate with time were given for the studied isothermal cure temperatures. To simulate the relationship between the cure rate and degree of cure, the autocatalytic model was used and the four parameters were calculated. Except in the late stage of the cure reaction, the model agrees well with the experimental data, especially at high temperatures. To account for the effect of diffusion on the cure rate, a diffusion factor was introduced into the model. The modified model greatly improved the predicted data at the late stage of cure reaction. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1074–1083, 2002
Compatibility studies on polystyrene and poly‐n‐butyl methacrylate
Authors: Somanathan N. , Sanjay A. , Arumugam V.
Published: August 2002

Polystyrene (PS) was a solution blended with poly‐n‐butyl methacrylate (PnBMA) at different compositions and the interactions between the two polymers were studied by using viscometry, ultrasound studies, and mechanical properties. All the properties show a characteristic variation in three stages. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2322–2330, 2002
Preparation of hyperbranched polymers by atom transfer radical polymerization
Authors: Bibiao Jiang , Yang Yang , Jian Deng , Shiyang Fu , Rongqi Zhu , Jianjun Hao , Wenyun Wang
Published: August 2002

A cheap acrylic AB* monomer, 2‐(2‐chloroacetyloxy)‐isopropyl acrylate (CAIPA), was prepared from 2‐hydroxyisopropyl acrylate with chloroacetyl chloride in the presence of triethylamine. The self‐condensing vinyl polymerization by atom transfer radical polymerization (ATRP), a “living”/controlled radical polymerization, has yielded hyperbranched polymers. All the polymerization products were characterized by proton nuclear magnetic resonance spectroscopy (1H NMR). CAIPA exhibited distinctive polymerization behavior that is similar to a classical step‐growth polymerization in the relationship of molecular weight to polymerization time, especially during the initial stage of the polymerization. However, a significant amount of monomer remained present throughout the polymerization, which is consistent with typical chain polymerization. Also, if a much longer polymerization time was used, the polymer became gel. As a result of the unequal reactivity of group A* and B*, the polymerization is different from an ideal self‐condensing vinyl polymerization: the branch structures of polymers prepared depend dramatically on the ratio of 2,2'‐bipyridyl to CAIPA. Hyperbranched polymers exhibit improved solubility in organic solvent, however, they have lower thermal stability than their linear analogs. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2114–2123, 2002
Mechanical properties of wood flake–polyethylene composites. II. Interface modification
Authors: Balasuriya P. W. , Ye L. , Mai Y.‐W. , Wu J.
Published: August 2002

This article discusses the methods of interface modification of composites based on raw wood flakes and high‐density polyethylene (HDPE) and the effects of these modifications on composite properties. An HDPE matrix was modified by a reaction with maleic anhydride (MA) in a twin‐screw extruder and then compounded with wood flakes to produce wood–polyethylene composites. Wood flakes were modified by a reaction with a silane coupling agent in an aqueous medium before being compounded with HDPE to produce silane‐modified WPCs. Differential scanning calorimetry and Fourier transform infrared spectroscopy data provide evidence for the existence of a polyethylene (PE)–silane‐grafted wood structure, which acts as a compatibilizer for wood flakes and PE. The results of MA‐modified composites indicate that some maleated HDPE is reacting with wood through esterification to form a compatibilizer for wood flakes and HDPE. Significant improvements in tensile strength, ductility, and Izod impact strength were obtained. Scanning electron micrographs provide evidence for strong interactions between the wood flakes and the matrix agent. The results indicate that 1–2 wt % MA modification on HDPE and 1–3 wt % silane treatment on wood flakes provide WPCs with the optimum properties. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2505–2521, 2002
DSC study on simultaneous interpenetrating polymer network formation of epoxy resin and unsaturated polyester
Authors: Ivanković M. , Džodan N. , Brnardić I. , Mencer H. J.
Published: August 2002

A kinetic study on simultaneous interpenetrating polymer network formation of epoxy resin based on diglycidyl ether of Bisphenol A (DGEBA) and unsaturated polyester (UP) was performed by means of differential scanning calorimetry (DSC). Isothermal DSC characterizations of neat resins and their mixture (in a weight ratio of 50/50) were performed at different temperatures. Dynamic DSC characterization of the systems were performed at three different heating rates. A lower total heat of reaction developed during simultaneous polymerization in dynamic DSC tests was found, compared to the total heats developed during pure resins network formation. This phenomenon can be interpreted as an effect of network interlock that could not be compensated for completely by an increase in curing temperature. The kinetics of the reactions was described by empirical models. The DGEBA, in a 50/50 UP/DGEBA blend, indicated a higher rate constant than the pure DGEBA. The obtained results suggests that the hydroxyl end group of UP in the blend provided a favorably catalytic environment for the DGEBA cure. The results are in good agreement with the literature data. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2689–2698, 2002
Microporous membranes of isotactic poly(4‐methyl‐1‐pentene) from a melt‐extrusion process. II. Effects of thermal annealing and stretching on porosity
Authors: Johnson Matthew B. , Wilkes Garth L.
Published: August 2002

A two‐part study utilizing isotactic poly(4‐methyl‐1‐pentene) (PMP) was undertaken to investigate a three‐stage process (melt‐extrusion/annealing/uniaxial stretching) (MEAUS) utilized to produce microporous films. In this report, the thermal‐annealing (second stage) and subsequent uniaxial‐stretching (third stage) results of selected PMP films from three resins, labeled A, B, and C, are discussed. From sequential analysis of the effect each stage had on the resulting microporosity, it was discovered that the melt‐extruded precursor morphology and orientation, as a consequence of the first‐stage extrusion parameters and resin characteristics, were crucial to controlling the membrane permeability. The annealing parameters were also critical, where a temperature of 205°C applied for 20 min under no tension was the optimum annealing condition for producing highly microporous PMP films upon stretching. For the conditions studied, the stretching parameters that were found to be the optimum for producing the desired characteristics in the final film were cold‐ and hot‐stretch temperatures of 70 and 180°C, respectively. The cold‐ and hot‐stretch extension levels concluded to be the best were a cold‐stretch extension of 80%, followed by hot stretching to 90%, and, thus, a total overall extension level of 170% for the processing window studied. However, these results were only with respect to resin A films, while resin B and C samples could not be produced into microporous films via the MEAUS process. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1076–1100, 2002; DOI 10.1002/app.10395
Crosslink reaction of natural rubber with thiuram sulphur donors in the presence of a thiuram monosulfide
Authors: González L. , Rodríguez A. , Del Campo A. , Marcos‐Fernández A.
Published: August 2002

The vulcanization of natural rubber was studied with the sulfurating agents dipentamethylene thiuram tetrasulfide (DPTT) and tetramethylene thiuram disulfide (TMTD) in the presence of tetramethyl thiuram monosulfide (TMTM). This last accelerant affects the rate and efficiency of the vulcanization as well as the structures of crosslinks formed by the two sulphur donors. It may give rise to a polymerization between adjacent double bonds and generate a inhomogeneous crosslink distribution with an adverse effect on physical properties. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 491–499, 2002
Fracture behavior of rubber‐modified injection molded poly(butylene terephthalate) with and without short glass fiber reinforcement
Authors: Yow B. N. , Ishiaku U. S. , Ishak Z. A. Mohd , Karger‐Kocsis J.
Published: August 2002

Fracture behavior of poly(butylene terephthalate) (PBT) and its rubber‐toughened (RT) 10 wt %) grades; ethylene‐co‐glycidyl methacrylate‐co‐methacrylate terpolymer‐toughened poly(butylene terephthalate) PBT/AX8900 (90/10), and Paraloid acrylic‐based rubber‐toughened poly(butylene terephthalate) PBT/EX2314 (90/10) was investigated using the fracture mechanics approach. The effects of controlling parameters such as type of impact modifier and deformation rate on fracture behavior of PBT and RT‐PBT were investigated. Fracture tests were carried out on notched compact tension (CT) specimens. Fracture toughness, Kc, and fracture energy, Gc, of PBT decreased as the test speed increased from 1 to 500 mm/min. An opposite trend was observed in PBT/AX8900 and PBT/EXL2314. The fracture properties of 30 wt % short glass fiber‐reinforced PBT (SGF‐PBT) and 10 wt % impact‐modified PBT composite (SGF‐RT‐PBT) were also studied. Incorporation of SGF into PBT has profoundly increased the fracture properties both at high and low speed. However, inclusion of 10 wt % of AX8900 into the reinforced PBT (PBT/AX8900/SGF) (60/10/30) adversely affected the fracture properties. EXL2314, on the other hand, showed a different effect, especially at high testing speed. Both types of impact modifiers were able to retain the flexural strength and flexural modulus of PBT. However, PBT/EXL2314 showed a better retention of flexural properties than PBT/AX8900. Incorporation of SGF in the EXL2314‐toughened PBT, i.e., PBT/EXL2314/SGF (60/10/30) also gave a better balance of flexural properties compared to PBT/AX8900/SGF (60/10/30). Both PBT/AX8900 and PBT/EXL2314 showed enhancement of impact strength on the unnotched specimens. The failure modes of CT and impact specimens of PBT, RT‐PBTs, and SGF‐RT‐PBTs were assessed using a scanning electron microscope (SEM). Brittle failure was observed for CT specimens of PBT at high testing speed, while incorporation of the impact modifier AX8900 and EXL2314 resulted in a shift of failure mode from brittle to ductile. SEM micrographs also revealed extensive fiber pull out in SGF‐PBT and SGF‐RT‐PBT. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1233–1244, 2002; DOI 10.1002/app.10446
Blends containing amphiphilic polymers IV. Poly(N‐1‐alkyl itaconamic acids) with poly(2‐vinylpyridine) and poly(4‐vinylphenol)
Authors: Urzua Marcela , Gargallo Ligia , Radić Deodato
Published: August 2002

The phase behavior of blends containing Poly(N‐1‐alkyl itaconamic acids) (PNAIA) with Poly(2‐vinylpyrindine) (P2VPy) and Poly(4‐vinylphenol) (P4VPh) were analyzed by Diferential Scanning Calorimetry (DSC) and Fourier Transform Infrared Spectroscopy (FTIR). Miscibility over the whole range of compositions is observed in both systems. All the blends show thermograms exhibiting distinct single glass transition temperatures (Tg), which are intermediate to those of the pure components. The Calorimetric Analysis using Gordon Taylor, Couchman, and Kwei treatments allows conclusion that interactions between the components is favorable to the miscibility. FTIR analysis of the blends suggests that the driving force for miscibility is hydrogen bonding formation. The variation of the absorptions of the carbonyl groups of PNAIA and the hydroxyl groups of P4VPh allows one to attribute the miscibility to weak acid base like interactions. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1245–1250, 2002; DOI 10.1002/app.10453
In vitro degradation of poly(L‐ lactic acid) fibers in phosphate buffered saline
Authors: Yuan Xiaoyan , Mak Arthur F. T. , Yao Kangde
Published: August 2002

In vitro degradation of poly(L‐lactic acid) (PLLA) fibers was studied by incubating the fibers in phosphate buffered saline (pH 7.4) at 37°C for 35–45 weeks. Three kinds of PLLA fibers with different diameters and different initial viscosity‐average molecular weights were tested. The viscosity‐average molecular weight, crystallinity, morphology, and tensile properties of the PLLA fibers were monitored along the degradation period. The results showed that the viscosity‐average molecular weight of the PLLA fibers dropped gradually during the in vitro degradation period, and it decreased by 40–60% at the end of the experimental period. The crystallinity of the PLLA fibers measured by differential scanning calorimetry was noted to increase slightly. The tensile moduli, ultimate strengths, and elongations of the fibers did not exhibit significant changes in 35 weeks of degradation but PLLA fibers with a smaller diameter of 113 μm showed significant decreases in their ultimate strengths with respect to the initial value after 35–45 weeks of degradation. Microcracks appeared on part of the fiber surfaces, which might ultimately lead to the decrease of the mechanical strength of the PLLA fibers. The spotty defects reported in this study apparently did not affect the mechanical properties of the fibers. The results suggested that the tensile properties of the PLLA fibers were mechanically stable in 35 weeks of in vitro degradation, although their molecular weights decreased remarkably and obvious spotty defects appeared on their surfaces. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 936–943, 2002
Molecular design of damping rubber based on polyacrylate‐containing silicone
Authors: Huang Guang‐Su , Jiang Lu‐Xia , Li Qiang
Published: August 2002

A series of damping rubbers based on poly(meth)acrylate and poly(meth)acrylate‐containing silicone rubbers has been prepared. The dynamical mechanical properties were evaluated by using a dynamic mechanical viscoelastometer (DMA). A detailed investigation is reported on the relationship of the damping capability of the poly(meth)acrylate rubbers with their composition and macromolecular architecture. Also discussed is the effect of two kinds of silicone elastomers on the damping performance of the polyacrylate‐containing silicone rubber. The results indicate that, in vulcanized rubber systems, both statistical copolymerization for multiple monomers and blending between immiscible polymers with close Tgs facilitate broadening the glass transition peaks. Furthermore, the molecular design is quite an effective approach in which the multiple monomers whose polymers have a ladder‐changing Tg are used to synthesize the damping rubber with the broad effective functional area. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 746–751, 2002
Preparation of polymer/inorganic nanoparticles composites through ultrasonic irradiation
Authors: Wang Qi , Xia Hesheng , Zhang Chuhong
Published: August 2002

In this paper, ultrasonic induced encapsulating emulsion polymerization was first used to prepare the novel polymer/inorganic nanoparticles composites. The behaviors of several inorganic nanoparticles (SiO2, Al2O3, TiO2) under ultrasonic irradiation, such as dispersion, crushing, and activation, were studied. The dispersion stability, morphology, and structure of the ultrasonic irradiated nanoparticles were characterized by means of transmission electron microscopy (TEM), Fourier transform infrared (FTIR), and spectrophotometry, respectively. The results show that the inorganic nanoparticles in the aqueous solution can redisperse more effectively by ultrasonic irradiation than by conventional stirring. This is the basis for preparation of polymer/inorganic nanoparticles composites. By this technique, the long‐term stable latex, which mainly consists of polymer/inorganic nanoparticles composite latex particles, were successfully prepared. TEM, FTIR, thermogravimetric analysis, X‐ray photoelectron spectroscopy, spectrophotometry, and element analysis confirmed that well‐dispersed nanoparticles were encapsulated by the formed polymer, and the thickness of encapsulating polymer layer was in the range of 5–65 nm. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1478–1488, 2001
Rigid, thermosetting liquid molding resins from renewable resources. I. Synthesis and polymerization of soy oil monoglyceride maleates
Authors: Can E. , Küsefoğlu S. , Wool R. P.
Published: August 2002

In this study, rigid thermoset polymers were prepared from radical copolymerization of the soybean oil monoglyceride maleates with styrene. In the first part of the study, soybean oil monoglycerides (SOMGs) were obtained from the reaction of soybean oil with glycerol at 220–240°C with an optimization of the reaction to maximize the monoglyceride yield. In the following step, SOMG were reacted with maleic anhydride at temperatures around 100°C to produce the SOMG maleate half esters. Different catalysts and different reaction conditions were examined to increase the maleate half esters' yields. The reactions were followed by IR and 1H NMR, and the products were characterized by mass spectrometry. In the final step, the radical initiated copolymerization of the SOMG maleates with styrene produced rigid, thermoset polymers. The emulsion copolymerization of the SOMG maleates with styrene was also carried out successfully without the addition of an emulsifier. The obtained polymers were characterized by IR and the crosslinked network structure of the copolymers was examined with the swelling behavior in different solvents. Mechanical properties of the cured resin such as Tg, dynamic flexural modulus, and surface hardness were also determined. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 69–77, 2001
Hygrothermal aging and tensile behavior of injection‐molded rice husk‐filled polypropylene composites
Authors: Ishak Z. A. Mohd. , Yow B. N. , Ng B. L. , Khalil H. P. S. A. , Rozman H. D.
Published: August 2002

The effect of the filler volume fraction on the tensile behavior of injection‐molded rice husk‐filled polypropylene (RH–PP) composites was studied. Hygrothermal aging behavior was also investigated by immersing the specimens in distilled water at 30 and 90°C. The kinetics of moisture absorption was studied from the amount of water uptake by specimens at regular interval times. It was found that the diffusion coefficient and the maximum moisture content are dependent on the filler volume fraction and the immersion temperatures. Incorporation of RH into the PP matrix has led to a significant improvement in the tensile modulus and a moderate improvement in the tensile strength. Elongation at break and energy at break, on the other hand, decreased drastically with the incorporation of the RH filler. The extent of deterioration incurred by hygrothermal aging was dependent on the immersion temperature. Both the tensile strength and tensile modulus deteriorated as a result of the combined effect of thermal aging and moisture attack. Furthermore, the tensile properties were not recovered upon redrying of the specimens. Scanning electron microscopy was used to investigate the mode of failure of the RH–PP composites. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 742–753, 2001
Thermooxidative decomposition and its kinetics on chlorinated natural rubber from latex
Authors: Zhong Jie‐Ping , Li Si‐Dong , Yu He‐Ping , Wei Yong‐Cai , Peng Zheng , Qu Ju‐Lan , Guo Chen‐Kun
Published: August 2002

Thermooxidative decomposition and its kinetics on chlorinated natural rubber (CNR) from latex are studied by thermal gravimetry (TG) analysis and TG coupled with FTIR spectroscopy. The thermooxidative decomposition of CNR is a two‐step reaction. The first step is the reaction of dehydrochlorination of which the reaction order (n) is 1.1; the reaction activation energy (E) increases linearly with the increment of the heating rate (B), and the apparent activation energy (E0) is 101.7 kJ/mol. The initial temperature of weight loss (T0) is 1.29B + 248.7, the final temperature of weight loss (Tf) is 0.86B + 312.4, and the temperature at the maximum weight loss ratio (Tp) is 1.05B + 286.2. The decomposition ratio at Tp (Cp) is not affected by B, and its average value is 38%. The decomposition ratio at Tf (Cf) is also not affected by B, and its average value is 60%. The second step is an oxidative decomposition reaction of the molecular main chain. The value of n is 1.1, E increases linearly with the increment of B, E0 is 125.0 kJ/mol, the relation between B and T is similar to that of the first step, and Cf approaches 100%. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1305–1309, 2001
Rheological and curing behavior of reactive blending. I. Maleated natural rubber–cassava starch
Authors: Nakason C. , Kaesman A. , Homsin S. , Kiatkamjornwong S.
Published: August 2002

Maleated natural rubber (MNR) was prepared and used as a blending composition and a compatibilizer for blending of natural rubber (STR 5L) and cassava starch. The melt rheological behavior in terms of Mooney viscosity, apparent shear stress, and shear viscosity at 100°C were quantified. We found that the pure MNR gave the lower apparent shear stress, shear viscosity than did those of the blends with cassava starch. The rheological data of the MNR blends increased with increasing quantity of cassava starch. The highest value was observed for the blend of MNR. The rheological value was as follows: MNR > STR 5L with MNR (as the compatibilizer) > STR 5L compounds. Furthermore, rheological properties increased with increasing the levels of compatibilizer (MNR). The rheological results were described in terms of intermolecular interaction between the polar groups in the natural rubber and cassava starch molecules. Each rubber blend was compounded, and their curing characteristics were studied. The pure MNR compounds exhibited a long delayed onset of vulcanization for approximately 10 min. The retardation was found, because the accelerator (MBT) reacted with the anhydrides in the compound instead of acting as an accelerator. The retardation was not observed for the compound with the cassava starch. The curing curves for all MNRs were not in equilibrium at a maximum torque, while the pure STR 5L compound gave a curing curve with a maximum torque and a slight reversion. The curing curve for the compound with MNR as the compatibilizer was a combination of the curing curves of MNR and STR 5L. That is, the curve was in equilibrium at the maximum torque and the short delayed action. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2803–2813, 2001
Effects of moisture content and heat treatment on the physical properties of starch and poly(lactic acid) blends
Authors: Ke Tianyi , Sun Xiuzhi
Published: August 2002

Starch, a hydrophilic renewable polymer, has been used as a filler for environmentally friendly plastics for about 2 decades. Starch granules become swollen and gelatinized when water is added or when they are heated, and water is often used as a plasticizer to obtain desirable product properties. The objective of this research was to characterize blends from starch and poly(lactic acid) (PLA) in the presence of various water contents. The effects of processing procedures on the properties of the blends were also studied. Blends were prepared with a lab‐scale twin‐screw extruder, and tensile bars for mechanical testing were prepared with both compression and injection molding. Thermal and mechanical properties of the blends were analyzed, and the morphology and water absorption of the blends were evaluated. The initial moisture content (MC) of the starch had no significant effects on its mechanical properties but had a significant effect on the water absorption of the blends. The thermal and crystallization properties of PLA in the blend were not affected by MC. The blends prepared by compression molding had higher crystallinities than those prepared by injection molding. However, the blends prepared by injection molding had higher tensile strengths and elongations and lower water absorption values than those made by compression molding. The crystallinities of the blends increased greatly with annealing treatment at the PLA second crystallization temperature (155°C). The decomposition of PLA indicated that PLA was slightly degraded in the presence of water under the processing temperatures used. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3069–3082, 2001
Condensation–addition‐type resole resins with phenyl ethynyl functions: Synthesis, characterization, and thermal properties
Authors: Reghunadhan Nair C. P. , Bindu R. L. , Ninan K. N.
Published: August 2002

Novel phenolic resins bearing methylol and phenyl ethynyl functions and curing by both condensation and addition mechanisms were synthesized by the reaction of 3‐(phenyl ethynyl) phenol (PEP) with formaldehyde under alkaline conditions. Resins with varying relative concentration of the two functional groups were synthesized and characterized. The resins underwent a two‐stage cure, confirmed by both DSC and DMA analyses. The low‐temperature cure due to methylol condensation led to early gelation of the system. The ultimate curing through addition reaction of phenylethynyl group required heating at 275°C. The cured resins exhibited better thermal stability and anaerobic char yield in comparison to a conventional resole. The thermal stability and char‐yielding property showed a diminishing trend with enhanced methylol substitution. Resin with F/P ratio less than unity offered excellent thermal stability and anaerobic char yield. The thermal degradation of the cured resins occurred in two kinetic steps. Methylene groups favored the initial degradation, whereas the higher temperature carbonization process was independent of the network structure. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3371–3377, 2001
Effect of alkalinity on the structure of phenol–formaldehyde resol resins
Authors: Luukko Petra , Alvila Leila , Holopainen Timo , Rainio Jouni , Pakkanen Tuula T.
Published: August 2002

Two phenol–formaldehyde resol resin series with different methylation‐ and condensation‐stage alkalinities were studied. The first series was impregnation resins having a methylation alkalinity between 0.5 and 1.5 wt % and a condensation alkalinity of 1.5 wt %. The second series was adhesive resins with a methylation alkalinity between 0.5 and 3.5 wt % and a condensation alkalinity of 6.0 wt %. The chemical structure was analyzed by 13C‐NMR spectroscopy, and reactivity, by differential scanning calorimetry (DSC). The methylation alkalinity was found to affect the distribution of the structural groups of both phenol–formaldehyde impregnation and adhesive resins, but not to the same extent as did the total condensation alkalinity. Also, the results of the DSC analysis illustrate best the reactivity differences due to the condensation alkalinity. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 258–262, 2001
Effect of atmosphere on the thermal decomposition of chlorinated natural rubber from latex
Authors: Li Si‐Dong , Cheung Man Ken , Zhong Jie‐Ping , Yu He‐Ping
Published: August 2002

The kinetics of the thermal decompositions of chlorinated natural rubber (CNR) from latex under both air and nitrogen atmospheres were studied with thermogravimetric analysis (TGA). The thermooxidative decomposition of CNR had two weight‐loss step changes in the TGA curves, which occurred at the two distinct temperature ranges of about 160–390 and 390–850°C, respectively. The gaseous products of the first step change were mainly HCl with a little CO2, and the apparent reaction order (n) was 1.1. The reaction activation energy (E) increased linearly with the increment of heating rate (B), and the apparent activation energy (E0), calculated by extrapolation back to zero B, was 101.7 kJ/mol. Bs ranging from 5 to 30°C/min were used. The initial temperature of weight loss (T0) was 1.31B + 252°C, where B is in degrees Celsius per minute. The final temperature of weight loss (Tf) was 0.93B + 310°C, and the temperature of maximum weight‐loss rate (Tp) was 1.03B + 287°C. The decomposition weight‐loss percentage at Tp (Cp) and that at Tf (Cf) were not affected by B, and the average values were 38 and 60%, respectively. The second weight‐loss step change was an oxidative decomposition of the molecular main chain. The value of n was 1.1. E increased linearly with the increment of B, and E0 was 125.0 kJ/mol. Cf after the second step approached 100%, which indicated complete decomposition. The thermal decomposition of CNR in a N2 atmosphere had only one weight‐loss step change with an n of 1.1. E increased linearly with the increment of B, and E0 was 98.6 kJ/mol. T0 was 1.25B + 251°C, Tf was 0.91B + 315°C, and Tp was 1.09B + 286°C. Cp and Cf were not affected by B, and the average values were 37 and 68%, respectively. The weight percentage of more stable, nonthermal decomposed residue was about 30%. The thermal decompositions of CNR in both atmospheres were similar, mainly by dehydrochlorination, at the low temperature range (160–390°C) but were different at the high temperature range (390–850°C). © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2590–2598, 2001
Electrical and mechanical properties of some polymeric composites
Authors: Mansour S. H. , Abd‐El‐Messieh S. L.
Published: August 2002

Two unsaturated polyester resins based on poly[propylene‐phthalate‐hexane‐maleate] (PE1) and poly[oxydiethylene‐phthalate‐hexane‐maleate] (PE2) were prepared and crosslinked with styrene monomer. The structure of the prepared polyesters was detected using IR and NMR. The thermal behavior of the styrenated polyesters was determined using differential scanning calorimetry. The dielectric properties for the PE1 and PE2 styrenated polyesters and their mixtures with different ratios were also studied with a frequency range of 100 Hz to 100 kHz at room temperature (≈25°C). The mixture containing a 50/50 ratio of PE1/PE2 possessed the most promising dielectric properties. Thus, this sample was chosen along with the two separate styrenated polyesters to be loaded with three different types of fillers: calcium carbonate, clay, and quartz. This investigation led to the conclusion that the sample containing 50/50 PE1/PE2 loaded with 60–70% clay possessed the most promising dielectric properties. The compressive and tensile strength values were also studied for PE1, PE2, and their 50/50 mixture filled with the three types of fillers with the recommended concentrations (60 and 70%). The results indicated that the quartz composite (60%) had the best mechanical properties with respect to the clay and calcium carbonate. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1167–1180, 2002
Preparation of biodegradable polyesters/high‐amylose‐starch composites by reactive blending and their characterization
Authors: Avella Maurizio , Errico Maria Emanuela , Rimedio Raffaello , Sadocco Patrizia
Published: August 2002

Two different biodegradable polyesters [polycaprolactone (PCL) and poly(3‐hydroxybutyrate‐co‐valerate) (PHBV)] were blended with a maize starch that had high amylose content through the use different reactive approaches. The compatibilization of both systems was obtained. PCL/starch composites were obtained by the addition of a third reactive component that was able to act as a coupling agent, and the reactive interface of PHBV/starch composites was improved during blending with an organic peroxide. Thermal, morphological, and mechanical characterization showed that the compatibilized composite materials had better final proprieties than neat materials or composites prepared without compatibilization. Finally, the degradation of all prepared materials by a compost simulation test was investigated. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1432–1442, 2002
Chitosan modified by poly(ethylene oxide): Film and mixture properties
Authors: Budtova Tatiana , Belnikevich Nina , Kalyuzhnaya Ljudmila , Alexeev Vladimir , Bronnikov Sergei , Vesnebolotskaya Svetlana , Zoolshoev Zoolsho
Published: August 2002

Chitosan + poly(ethylene oxide) mixtures and films prepared from these mixtures were studied by rheological, absorption of solvent vapors, SANS, and mechanical testing methods. At a stoichiometric chitosan:poly(ethylene oxide) monomer:monomer composition, the mechanical properties of chitosan + poly(ethylene oxide) film are the best as compared with those of the initial components or of other compositions. This film composition is shown to be less heterogeneous. Chitosan and poly(ethylene oxide) are proved to be slightly incompatible polymers. This is supposed to induce the two components to align and to order at their stoichiometric composition, leading to the improvement in the mechanical properties. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1114–1122, 2002; DOI 10.1002/app.10319
Environmental impact of antifouling technologies: state of the art and perspectives
Authors: Terlizzi A. , Fraschetti S. , Gianguzza P. , Faimali M. , Boero F.
Published: August 2002

1. Marine fouling affects most man‐made surfaces temporarily or permanently immersed in the sea, resulting in significant (or substantial) economic costs. Intense research is aimed at preventing or reducing fouling.

2. The most widespread solution to avoid fouling formation is to make surfaces unsuitable for settlers, coating them with antifouling (AF) paints containing toxic compounds. Most AF agents (e.g. tributyltin, (TBT)) have undesirable effects on non‐target species, including commercially important organisms.

3. To date, the use of TBT in AF paints has been restricted (but not prohibited) in a number of countries and new biocides are in use.

4. The environmental problems posed to marine systems by AF technologies are here briefly reviewed.

5. New approaches focusing on alternatives to the use of biocidal AF paints are also considered and discussed. Copyright © 2001 John Wiley & Sons, Ltd.
Qualitative modelling for the development of a sustainable management strategy for the Peruvian scallop Argopecten purpuratus (Lamarck 1819)
Authors: Ortiz Marco , Wolff Matthias , Mendo Jaime
Published: August 2002

This study is the first attempt using Levins's Theory (loop analysis) in order to develop a sustainable management for the scallop, Argopecten purpuratus, fishery in Peru during El Niño‐Southern Oscillation events (ENSO) and upwelling conditions. Based on this theoretical framework, it was possible to estimate the local stability for each of these model systems and to follow the qualitative changes of the variables in response to external factors.

Based on our results, we suggest the following management policies to be implemented: (1) during ENSO events the size at the first capture of the scallops should be >70 mm and (2) the increase in the number of fishermen during ENSO events must be prevented. Both measures increase the sustainability of fishery under ENSO and upwelling conditions. The ecological models predict that during ENSO and upwelling events, any management strategy to increase the recruitment of the scallop would not have a positive impact on the adult stock.

Finally, we suggest that more efforts must be focused on the development of extended eco‐social models, which incorporate further social and economic variables, increasing realism of the abstractions for this fishery activity.

Copyright © 2002 John Wiley & Sons, Ltd.
Evidence that dopamine‐beta‐hydroxylase immunoreactive neurons in the lateral reticular nucleus project to the spinal cord in the rat
Authors: Lee Hyun S. , Waterhouse Barry D. , Mihailoff Greg A.
Published: August 2002

The existence of noradrenergic projections from the lateral reticular nucleus (LRt) to the dorsal quadrant of cervical, thoracic, or lumbar spinal cord was investigated using a combined method of WGA‐apo‐HRP‐gold retrograde tracing and dopamine‐beta‐hydroxylase (DBH) immunocytochemistry. Preliminary retrograde tracing studies indicated that LRt neurons projecting to cervical, thoracic, or lumbar spinal cord were characteristically located near the perimeter of the LRt. Double‐labeling experiments demonstrated that a portion of these peripherally‐located, spinal‐projecting neurons were DBH‐immunoreactive. Double‐labeled neurons were also located at the parvocellular division of the contralateral LRt in the thoracic injection cases. Double‐labeled neurons were not observed at the subtrigeminal division in cervical, thoracic, or lumbar injection case. The results suggest the possibility that the noradrenergic LRt‐spinal pathway might be involved in a variety of pain processing and cardiovascular regulatory functions in the rat. Anat Rec 263:269–279, 2001. © 2001 Wiley‐Liss, Inc.
Sound‐generating and ‐detecting motor system in catfish: Design of swimbladder muscles in doradids and pimelodids
Authors: Ladich Friedrich
Published: August 2002

Catfishes have evolved a diversity of swimbladder muscles serving in the generation of different sounds and probably other acoustic functions. In order to find out if anatomical and acoustical differences are parallelled by fine structural differences, I examined the sonic muscles of the doradid Platydoras and the pimelodid Pimelodus by gross dissections and ultrastructural methods. In Platydoras, the sound‐generating (drumming) muscle (DM) inserts on a dorsal bony plate that vibrates the swimbladder. In pimelodids, the large DM attaches directly on the ventral surface of the swimbladder, whereas the small tensor tripodis muscle (TT) inserts on the rostral surface near the tripus, the most caudal Weberian ossicle. Fibers of all three muscles possess an extensive development of sarcoplasmatic reticulum (SR) in association with very thin myofibrils (MF) but differed widely in their arrangement. In Platydoras, ribbons of MFs are arranged radially around a central core. Mitochondria were found within the core and the peripheral sarcoplasm. Pimelodus does not have a differentiated core and the cross‐sectional area of DM‐MFs is about 15% larger as determined by stereological measurements. The TT possesses shorter sarcomeres and more mitochondria than DMs, which were primarily found between MFs. This suggests faster contraction properties and greater resistence to fatigue compared with sonic muscles. Data indicate that the higher amount of DM‐myofibrils in pimelodids might result in stronger muscle contractions and, presumably, in higher sound intensities. The fine structure of the TT reveals that contractions most likely prevent transmission of swimbladder vibrations to the inner ear via the Weberian ossicles during vocalization. Anat Rec 263:297–306, 2001. © 2001 Wiley‐Liss, Inc.
Roles of peritrophic membranes in protecting herbivorous insects from ingested plant allelochemicals
Authors: Barbehenn Raymond V.
Published: August 2002

Four mechanisms by which peritrophic membranes (PMs) potentially protect herbivorous insects from ingested allelochemicals are reviewed: adsorption, ultrafiltration, polyanion exclusion, and the capacity of PMs to act as antioxidants. Most of the research on the protective roles of PMs against ingested allelochemicals has focused on their impermeability to tannins. Adsorption of tannins by the PMs in grasshoppers may limit their permeability, but ultrafiltration of tannin complexes in the caeca is an alternative explanation. Polyanion exclusion does not explain the impermeability of caterpillar PMs to tannins (polyphenolate anions). Ultrafiltration remains the most likely mechanism by which tannins, and other tested allelochemicals, are retained in the endoperitrophic space. Although the pores in PMs are too large to impede the passage of most free allelochemicals, large allelochemical complexes are retained. Such complexes form in the gut fluid of caterpillars between tannic acid, proteins, lipids, and polyvalent metal cations, and also in the gut fluid of grasshoppers (Melanoplus sanguinipes) between some amphiphilic allelochemicals (digitoxin) and surfactant micelles. Further work is needed to examine the role of PMs as antioxidants in vivo, such as their potential to bind catalytically‐active metal ions. Arch. Insect Biochem. Physiol. 46:86–99, 2001. © 2001 Wiley‐Liss, Inc.
Molecular evidence for two vitellogenin genes and processing of vitellogenins in the American cockroach, Periplaneta americana
Authors: Tufail M. , Hatakeyama M. , Takeda M.
Published: August 2002

The American cockroach, Periplaneta americana has two vitellins (Vn1 and Vn2) and corresponding vitellogenins (Vg1 and Vg2). Vns/Vgs were separated on the SDS‐PAGE as three major polypeptide bands [170, 100 (multisubunits), and 50 kD] and a minor polypeptide band (150 kD) both in the egg (mature terminal oocyte) extract and in the female hemolymph. We previously cloned one Vg (Vg1) cDNA and showed that the 170‐kD polypeptide originated from the C‐terminus of the Vg1. In the present study, we cloned the other Vg (Vg2) cDNA. It is 5,826 bp long encoding 1,876 amino acid residues (including 16 residues for putative signal peptide) in a single ORF. The deduced amino acid sequences of both Vgs (Vg1 and Vg2) of P. americana showed 30% identity. The GL/ICG motif is followed by eight cysteine residues at conserved locations near the C‐terminal and the DGXR motif starts 18 residues upstream of the GL/ICG motif. The chemically determined N‐terminal amino acid sequences of the 150‐kD and of the 50‐kD polypeptides matched exactly with each other and with the deduced N‐terminal amino acid sequence of the Vg2 cDNA. The pattern of processing in P. americana Vns/Vgs is discussed. Arch. Insect Biochem. Physiol. 48:72–80, 2001. © 2001 Wiley‐Liss, Inc.
Effects of calcium channel antagonists on the corpora allata of adult male loreyi leafworm Mythimna loreyi: Juvenile hormone acids release and intracellular calcium level
Authors: Hsieh Yi‐Chun , Hsu Err‐Lieh , Chow Ying‐Shing , Kou Rong
Published: August 2002

The effects of voltage‐dependent calcium channel (VDCC) antagonists and the non‐specific calcium channel antagonists on both juvenile hormone acids (JHA) release and cytosolic free calcium concentration ([Ca2+]i) are investigated in the corpora allata (CA) of the adult males loreyi leafworm Mythimna loreyi. The VDCC antagonists used in this study are: the L‐type antagonists diltiazem, nifedipine, and verapamil, the N‐type antagonist ω‐Conotoxin (CgTx) GVIA, the N‐ and P/Q‐type antagonist ω‐CgTx MVIIC, and the T‐type antagonist amiloride. The non‐specific calcium channel antagonists used in this study were cadmium (Cd2+), cobalt (Co2+), nickle (Ni2+), and lanthanum (La3+). The results show that both the DHPs‐sensitive L‐type antagonist nifedipine and the N‐type antagonist ω‐CgTx GVIA were able to inhibit JHA release, but only ω‐CgTx GVIA was able to reduce the [Ca2+]i. Among the non‐specific calcium channel antagonists, Cd2+ is the most potent in reducing JHA release but without obvious effect on the [Ca2+]i, La3+ significantly increases the [Ca2+]i but without effect on JHA release. Arch. Insect Biochem. Physiol. 48:89–99, 2001. © 2001 Wiley‐Liss, Inc.
Prompt magnetic investigations of archaeological remains in areas of infrastructure development: Israeli experience
Authors: Eppelbaum Lev V. , Khesin Boris E. , Itkis Sonya E.
Published: August 2002

Magnetic prospecting is the most widely used method for the investigation of archaeological remains in the world. This method is often applied before and during various engineering exploration (e.g. road construction, preparing areas for various types of building) and areas of agricultural utilization. Taking into account an extremely high concentration of archaeological sites of different age at Israeli territory, prompt geophysical–archaeological assessment of areas allocated for engineering and agricultural utilization, is a necessary preliminary component of the design process. However, noise both of natural and artificial origin strongly complicates interpretation of observed magnetic anomalies. The most significant disturbing factors are oblique magnetization (magnetization vector in the Israeli territory is inclined about 45°), complex geological structure (presence of a variety of disturbing bodies) of investigated site, influence of rugged topography, as well as influence of modern iron‐containing objects. The non‐conventional procedures developed by the authors are intended for application in such complicated environments and include elimination of noise from various sources, selection of ‘useful’ anomalies against the noise background, qualitative and quantitative interpretation of anomalies and three‐dimensional physical–geological modelling. Effective integration of these procedures with other interpretation methods allowed rapid localization of tens of archaeological remains and their protection from unpremeditated destruction. Copyright © 2001 John Wiley & Sons, Ltd.
Suppression of autoimmune arthritis in interleukin‐1‐deficient mice in which T cell activation is impaired due to low levels of CD40 ligand and OX40 expression on T cells
Authors: Saijo Shinobu , Asano Masahide , Horai Reiko , Yamamoto Hiroaki , Iwakura Yoichiro
Published: August 2002

Objective

To elucidate the roles of interleukin‐1 (IL‐1) in the development of 2 etiologically different rheumatoid arthritis (RA) models: the type II collagen (CII)–induced arthritis (CIA) model and the human T cell leukemia virus type I transgenic (HTLV‐I Tg) mouse model.

Methods

For the CIA model, DBA/1J‐background IL‐1α−/−, IL‐1β−/−, IL‐1α/β−/−, and wild‐type littermate mice were immunized with CII. For the HTLV‐I Tg model, BALB/c IL‐1β−/− or IL‐1α/β−/− mice were crossed with HTLV‐I Tg mice. The effects of IL‐1 deficiency were assessed as follows: Development of arthritis was assessed both macroscopically and microscopically. Serum antibody titer was measured by enzyme‐linked immunosorbent assay. Proliferative response of lymph node cells was assayed by measurement of 3H‐thymidine incorporation. Expression of T cell surface molecule CD40 ligand (CD40L) and OX40 was determined by multicolor flow cytometric analysis.

Results

The development of arthritis was markedly suppressed in IL‐1α/β−/− mice in both models, although the effect was less prominent in HTLV‐I Tg mice. Deficiency of only IL‐1α or only IL‐1β was also associated with disease suppression. Antibody production after immunization with CII was normal in IL‐1α/β−/− mice, while autoantibody production was suppressed in IL‐1α/β−/− HTLV‐I Tg mice. In IL‐1α/β−/− mice, the T cell proliferative response against CII was greatly reduced in both the CIA and the HTLV‐I Tg models, suggesting inefficiency of T cell activation. Furthermore, expression of CD40L and OX40 on T cells was greatly reduced in IL‐1α/β−/− mice.

Conclusion

These observations suggest that T cell activation by IL‐1 is important for the development of autoimmunity and arthritis in these mice.