bluuebunny/crossref_metadata_2025 huggingface dataset:
Natural zeolite polypropylene composite film preparation and characterization
Authors: Özmihçi F. , Balköse D. , Ülkü S.
Published: October 2004

In this research, the preparation and characterization of polypropylene (PP) and natural zeolite composites were studied. Natural zeolite mined in Gördes, Turkey was used as an alternative filler to CaCO3. Films were prepared by the extrusion of PP, and surface‐modified zeolite was made by polyethylene glycol 4000 with 2–4% zeolite. Zeolite‐filled composites had densities between 0.73 and 0.83 g/cm3 and had void fractions of 0.07–0.20. Although the permeability of water vapor through 2% zeolite‐filled composites was very small, 4% zeolite‐filled films had very high permeabilities. The yield stresses of 2–4% zeolite‐containing films were around 26–27 N/mm2 and were lower than that of PP, which indicated no adhesion between PP and zeolite. The effect of zeolite on the thermal degradation behavior in air and in a N2 atmosphere was also studied. In air, zeolites did not cause the oxidation of PP. In a N2 atmosphere, although the start of the thermal degradation of PP was retarded by zeolite, composites degraded at a faster rate than PP once the degradation started. At a processing temperature of 200°C, zeolites had no effect on the degradation of PP. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2913–2921, 2001
Blends of polypropylene with poly(vinyl butyral)
Authors: Cascone E. , David D. J. , Di Lorenzo M. L. , Karasz F. E. , Macknight W. J. , Martuscelli E. , Raimo M.
Published: October 2004

The thermal stability, crystallization behavior, and morphology of poly(vinyl butyral) (PVB) with differing compositions of vinyl alcohol and butyral units were investigated. It was found that the glass‐transition temperature of PVB decreases with increasing concentration of butyral units, mainly because of the reduced number of hydrogen bonds between hydroxyl groups of the chains. PVB samples with high vinyl alcohol content (≥63.3% by weight) are crystallizable and present an endothermic melting peak in the range 170–220°C. The thermal stability of PVB is also influenced by composition and increases with the number of butyral units. The thermal and crystallization characteristics of PVB were compared with those of neat polyvinyl alcohol (PVA), and the differences explained in terms of molecular structure. Two amorphous PVB samples, containing 31 and 14 wt % of vinyl alcohol units, respectively, were blended with isotactic polypropylene grafted with maleic anhydride (PP–MA), the latter of which was present to favor compatibilization of the components through chemical reaction or dipolar interactions involving the anhydride groups of the PP–MA and the hydroxyl groups of PVB. Properties of PP–MA/PVB 90/10 blends, prepared by melt extrusion, were compared to those of neat PP–MA. Both the PVBs used were immiscible with PP–MA, as indicated by the invariance of glass‐transition temperatures with the composition of the blends. However, a high level of compatibility between the components was achieved because the blends showed good mechanical properties that were comparable to, or even superior to, those of neat PP–MA. The analysis of the crystallization kinetics, performed both in isothermal and nonisothermal modes, showed that crystallization of polypropylene is only slightly influenced by the presence of the PVB phase. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2934–2946, 2001
Off‐line monitoring of butyl acrylate and vinyl acetate homopolymerization and copolymerization in toluene
Authors: Jovanović Renata , Dubé Marc A.
Published: October 2004

A study of butyl acrylate (BA) and vinyl acetate (VAc) solution homopolymerization and copolymerization in toluene was carried out. The conversion and copolymer composition were monitored using traditional techniques (gravimetry and 1H‐NMR spectroscopy) and attenuated total reflectance‐Fourier transform IR (ATR‐FTIR) spectroscopy with a diamond‐composite probe and light conduit technology. The peak height of the characteristic absorbances of the monomer(s) during the course of the reaction was used to calculate the conversion and copolymer composition for the ATR‐FTIR monitoring. The data obtained using a ReactIR™ 1000 reaction analysis system in the off‐line mode showed very good agreement with data obtained using traditional techniques. The solvent effects on BA and VAc solution homopolymerizations and copolymerizations in toluene were also investigated. Improvement to model predictions was obtained by allowing the lumped constant (kp/k) to vary with the solvent concentration. Experimental data and model predictions of the number‐ and weight‐average molecular weights for the investigated systems are also presented. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2958–2977, 2001
Suspension characteristics of borate‐crosslinked gels: Rheology and atomic force microscopy measurements
Authors: Goel Naval , Shah Subhash N. , Yuan Wei‐Li , O'Rear Edgar A.
Published: October 2004

Borate‐crosslinked guar gels were prepared and characterized to understand their capability to suspend and transport sand particles through a fracture created in a petroleum reservoir. In this study the crosslinked gels were formulated by varying the borate crosslinker concentrations that were selected such that the gels satisfied the minimum viscosity criteria (100 cP at 100/s) used to evaluate crosslinked gels for their suspension capabilities. However, some of these gels did not exhibit satisfactory particles transport through a slot that models a parallel fracture. These gels were then characterized using oscillatory measurements and atomic force microscopy (AFM) to understand the influence of the microscopic behavior of the crosslinked gels on their macroscopic performance in the slot. The results showed that the suspension transport characteristics of these gels could be described through crosslinked networks formed across the guar polymer. The AFM images and rheological measurements of these gels suggest that the elastic modulus provides more useful information than the viscosity about the crosslinked gel structure and their capability to suspend sand particles. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2978–2990, 2001
Modification of three‐component bismaleimide resin by poly(phthaloyl diphenyl ether) and related copolymers
Authors: Iijima Takao , Yuasa Noriyuki , Tomoi Masao
Published: October 2004

A three‐component bismaleimide resin, composed of 4,4′‐bismaleimidodiphenyl methane (BDM), o,o′‐diallyl bisphenol A (DBA), and o,o′‐dimethallyl bisphenol A (1.0/0.3/0.7 eq ratio) was used as a parent bismaleimide resin. Modification of the three‐component bismaleimide resin was examined by blending it with poly(ether ketone ketone)s. Poly(ether ketone ketone)s include poly(phthaloyl diphenyl ether) (PPDE), poly(phthaloyl diphenyl ether‐co‐isophthaloyl diphenyl ether) (PPIDE), and poly(phthaloyl diphenyl ether‐co‐terephthaloyl diphenyl ether) (PPTDE). The PPIDE (51 mol % isophthaloyl) and PPTDE (44 mol % terephthaloyl) were more effective as modifiers for the bismaleimide resin than was PPDE. For example, the fracture toughness (KIC) for the modified resin increased 30% with no deterioration in the flexural strength and modulus with a 15 wt % inclusion of PPTDE (MW 23,400) compared to the parent three‐component bismaleimide resin: the KIC increased 95% compared to the value for the Matrimid 5292 resin composed of BDM and DBA. The morphologies of the modified resins changed from particulate to cocontinuous phase structures, depending on the modifier structure and concentration. Toughening of the cured bismaleimide resin could be achieved because of the cocontinuous phase structure. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2991–3000, 2001
Experimental estimation of gas‐transport properties of linear low‐density polyethylene membranes by an integral permeation method
Authors: Villaluenga J. P. G. , Seoane B.
Published: October 2004

In recent years, we have investigated gas‐transport phenomena in coextruded linear low‐density polyethylene (LLDPE) membranes. For the most part, coextruded LLDPE membranes were investigated because of their excellent mechanical properties, which explain their extensive use in the packaging industry. Because of the small thickness of coextruded LLDPE membranes, significant errors can be involved in the determination of the diffusion coefficient of gases in the membranes by the time‐lag method. To obtain more precise transport parameters for LLDPE membranes, we determined the permeability and diffusion coefficients for O2, CO2, He, and N2 from 298 to 348 K by employing an alternative method recently developed. The results indicate that the procedure used in this study for determining the diffusivity of gases in membranes was precise and more efficient than a method based on the evaluation of the time‐lag parameter. With respect to permeability, the coefficients obtained in this work agree satisfactorily with those obtained by the time‐lag method. In general, the permeability and diffusivity results are in satisfactory agreement with the literature values reported for semicrystalline polyethylene membranes. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3013–3021, 2001
Interfacial and mechanical properties of γ‐Fe2O3/segmented polyurethane/poly(vinyl chloride) composites
Authors: Sudaryanto  , Nishino Takashi , Ueno Masaki , Asaoka Seiji , Nakamae Katsuhiko
Published: October 2004

Segmented polyurethane (SPU)/poly(vinyl chloride) (PVC) blends were particulated with γ‐Fe2O3. Interfacial properties of the composite were studied through the adsorption behaviors of SPU and PVC and their blends on γ‐Fe2O3 particles surface. Mechanical properties of the composite were measured with dynamic mechanical analysis and tensile test measurements. PVC with functional groups (FPVC), because of strong interactions, showed preferential adsorption on γ‐Fe2O3 compared with SPU and PVC. Moreover, the γ‐Fe2O3 particles were covered by FPVC in the γ‐Fe2O3/SPU/FPVC composite. The adsorption layer of FPVC protected SPU from catalytic degradation by γ‐Fe2O3, resulting in increasing hydrolytic stability for SPU. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3030–3035, 2001
Characterization of the vibrational damping loss factor and viscoelastic properties of ethylene–propylene rubbers reinforced with micro‐scale fillers
Authors: Kwak G. H. , Inoue K. , Tominaga Y. , Asai S. , Sumita M.
Published: October 2004

The influence of microscale fillers on ethylene–propylene rubbers (EPR) was examined with respect to their vibrational damping capacity and viscoelastic properties. The vibrational damping and dynamic mechanical properties of reinforced EPR were studied in systematic and comparative ways that reinforced the evidence of a direct relation between the vibrational damping loss factor and its mechanical damping loss factor. In this study, the sensitivity of the vibrational damping loss factor of reinforced EPR was quantified with respect to the variation in thickness, filler type, and filler content. Dynamic mechanical relaxation behaviors were also analyzed. The viscoelastic properties in terms of the storage modulus, loss modulus, mechanical damping loss factor, and frequency dependence of molecular relaxation showed interesting results with the filler types and compositions that had good correspondence with the vibrational damping behaviors. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3058–3066, 2001
Dimethylammonium dimethyldithiocarbamate‐accelerated sulfur vulcanization. I. Thermal stability and reactions with curatives
Authors: Shumane M. , Gradwell M. H. S. , Mcgill W. J.
Published: October 2004

To investigate its thermal stability and reactivity towards other accelerators dimethylammonium dimethyldithiocarbamate ((dma)dmtc) was heated at programmed heating rates in sealed and open pans in a differential scanning calorimeter and on a thermobalance. (Dma)dmtc was heated on its own, in rubber compounds and in mixes with tetramethylthiuram disulfide, zinc dimethyldithiocarbamate, and ZnO. In open systems (dma)dmtc readily sublimes at temperatures well below its melting point, and it is almost as rapidly lost when compounded on its own with rubber. No decomposition is observed at vulcanization temperatures and (dma)dmtc is unreactive towards tetramethylthiuram disulfide and zinc dimethyldithiocarbamate. Moisture does not promote its decomposition. Reaction with ZnO to give zinc dimethyldithiocarbamate is restricted to the surface of ZnO particles. (Dma)dmtc is soluble in water in which it dissociates. It must be concluded that when its is included in formulations, (dma)dmtc, per se, would act as a vulcanization accelerator; it does not decompose to dimethyldithiocarbamic acid and dimethylamine, both of which are known accelerators. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3067–3073, 2001
Barium chloride crosslinked carboxymethyl guar gum beads for gastrointestinal drug delivery
Authors: Thimma Reddy T. , Tammishetti Shekharam
Published: October 2004

A mild method for microencapsulation of sensitive drugs, such as proteins, employing a suitably derivatized carboxymethyl guar gum (CMGG) and multivalent metal ions like Ca++ and Ba++ is reported. Initially, guar gum is derivatized with carboxymethyl groups so that it forms durable, self‐standing microbeads when its solution is dropped into CaCl2 or BaCl2 solutions. The swelling data of Ca++ and Ba++ crosslinked beads suggest that Ba++ crosslinks CMGG much more efficiently than Ca++. The drug loading efficiency of these Ba++/CMGG beads, as a function of concentration of both metal ion as well as drug, was then determined using Bovine Serum Albumin as a model drug. The ability of these beads to protect the drug from the acidic environment of the stomach was investigated. It was found that a very little amount of the drug is released from the beads when they are suspended in NaCl–HCl buffer of pH 1.2 for 6 h. The beads were also shown to release almost the entire encapsulated drug when exposed to TRIS–HCl buffer of pH 7.4. Thus, the results indicate that Ba++ crosslinked carboxymethyl guar gum beads can be used for gastrointestinal drug delivery. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3084–3090, 2001
Low‐energy electron beam‐induced cationic polymerization with onium salts
Authors: Boey F. Y. C. , Chia N. K. , Rath S. K. , Abadie M. J. M.
Published: October 2004

Demand for higher polymer performance with very short cure times has resulted in the development of low energy electron beam processes. This article presents the results of such a process for curing two epoxy systems, namely 3,4‐epoxycyclohexylmethyl‐3′,4′‐epoxycyclohexane carboxylate and di‐glycidyl ether of bisphenol A (DGEBA), using the cationic photoinitiator salts, triarylsulfonium hexafluoroantimonate, and diaryliodonium hexafluoroantimonate, respectively. Glass transition temperature measurements were done using a modulated DSC method while the degree of conversion was measured using FTIR spectroscopy. Results indicate that for both epoxy systems a relatively low dosage of not more than 5 Mrad was sufficient to achieve up to 60% conversion, with up to 80% conversion achievable using 30 Mrad. The diaryliodonium salt appeared to be more effective than the sulphonium salt in the above study. The effect of varying photoinitiator concentration and the resulting glass transition temperature has been studied. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3099–3108, 2001
Structure and properties of semiinterpenetrating polymer networks based on polyurethane and nitrochitosan
Authors: Liu Haiqing , Zhang Lina
Published: October 2004

Two semiinterpenetrating polymer networks (semi‐IPNs) based on trihydroxyl methylpropane–polyurethane (T‐PU) or castor oil–polyurethane (C‐PU) were prepared by curing the mixed solution of the polyurethane prepolymer and nitrochitosan (NCH). During the curing process, crosslinking and grafting reaction between the molecules of the PU prepolymer and NCH occurred, because of the high reactivity of remaining hydroxyl groups in the NCH with NCO groups of PU. The structure of the original semi‐IPN sheets and the sheets treated with acetone were studied by infrared, 13C‐NMR, scanning electron microscopy, and dynamic mechanical analysis, showing interpenetration of NCH molecules into the PU networks. When nitrochitosan content (CNCH) was lower than 10 wt %, the semi‐IPN sheets T‐PU and C‐PU had higher density and tensile strength (σb) than the systems with CNCH more than 20%. The trihydroxymethyl propane‐based PU reacted more readily with nitrochitosan to form the semi‐IPNs than castor oil‐based PU. The semi‐IPN coatings T‐PU and C‐PU were used to coat cellophane, resulting in intimate interfacial bonding. The mechanical strength and water resistivity of the cellophane coated with T‐PU coating were improved remarkably. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3109–3117, 2001
Synthesis and characterization of ion‐conducting polymer systems based on EPDM blends
Authors: Bashir H. , Linares A. , Acosta J. L.
Published: October 2004

We report on the preparation and characterization of new polymeric ionomers based on EPDM with a high norbornene content. The sulfonation level is determined by means of X‐ray photoelectron spectroscopy and the microstructural characterization is obtained both through differential scanning calorimetry and dynamo‐mechanic analysis. In addition, the effects of certain plasticizers and polymers on the microstructure of these materials were studied, as well as their conducting properties, with special attention to this latter type of behavior, in view of the interest aroused by these materials as membranes in polymer fuel cells. From the obtained results, some of the synthesized membranes can be used for fuel cells because their high conductivity (≥10‐2 S/cm) and their good dimensional stability (any shrinkage observed). © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3133–3141, 2001
Arylenecyclosiloxane–dimethylsiloxane copolymers
Authors: Mukbaniani O. , Koiava N. , Karchkhadze M. , Tkeshelashvili R. , Shengelia M. , Khananashvili L.
Published: October 2004

The heterofunctional condensation reaction of 1,4‐bis(phenyldichlorosilyl)benzene with dihydroxydiphenylsilane at a 1:4 ratio of initial compounds in the presence of pyridine was investigated and tetrakis(hydroxydiphenylsiloxy)‐1,4‐bis(phenylsilyl)benzene was obtained. The heterofunctional condensation of the tetrakis(hydroxydiphenylsiloxy)‐1,4‐bis(phenylsilyl)benzene with organotrichlorosilanes at a 1:2 ratio of initial compounds in the presence of pyridine produced dichloro‐containing arylenecyclosiloxanes. The dichloro‐containing arylenecyclosiloxanes were obtained in one stage by successive heterofunctional condensation of 1,4‐bis(dichlorophenylsilyl)benzene with dihydroxydiphenylsilane and organotrichlorosilanes in a 1:4:2 ratio in the presence of pyridine. It was established that the yields of dichloro‐containing products were lower. Hydrolysis of dichloroarylenecyclosiloxanes in a neutral condition produced corresponding dihydroxy compounds. Heterofunctional polycondensation of dicloro(dihydroxy)arylenecyclosiloxanes with α,ω‐dihydroxy(bisdimethylamino)dimethylsiloxanes was used to obtain arylenecyclosiloxane‐dimethylsiloxane copolymers. Thermogravimetric, thermomechanical, and roentgenographic investigations of the synthesized copolymers were carried out. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3142–3148, 2001
Studies on the kinetics of orientation and crystallization of nylon‐66 during high‐speed melt spinning
Authors: Wang Huaping , Wang Biao , Hu Xuechao
Published: October 2004

A new way of applying on‐line experimental data and basic theory to study the mechanism of orientation of a high‐speed melt spinning process is described. The relationship of birefringence and stress for Nylon‐66 was developed to understand the phenomena in the spinning line. The value of birefringence along the spinning line was calculated by various models to predict the orientation change. By comparison of the model prediction and on‐line experimental birefringence, a suitable mechanical model to simulate the change of the profiles along the spinning line was chosen, and the structural development mechanism is discussed. The results show that the orientation mechanism of high‐speed melt spinning of Nylon‐66 is determined by deformation and deformation rate along the spinning line. For Nylon‐66, molecular and crystal orientations develop independently and are controlled by the rotation of crystals and chain segments in the deformation field. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3157–3163, 2001
Preparation and characterization of polyamide‐6 with three‐branched chains
Authors: Dai Lixing , Huang Nanxun , Tang Zhilian , Hungenberg Klaus‐Dieter
Published: October 2004

With trimesinic acid as a molecular weight regulator, the hydrolytic polymerization of ϵ‐caprolactam was carried out, and nylon‐6 or polyamide‐6 with three‐branched chains was obtained. Through a systematic study of the effects of conditions such as the reaction time and concentration of trimesinic acid on the polymerization, we found that the conversion of caprolactam was almost insensitive to the initial concentrations of the regulators, but the relative viscosity of the polymer decreased with increasing trimesinic acid. Characterization investigations showed that differential scanning calorimetry curves changed from a single peak for normal nylon‐6 to one main peak and one shoulder or one small peak for the branched polymer; the melting point of the star‐shaped nylon‐6 decreased with an increasing amount of trimesinic acid, whereas its crystallization temperature was higher than that of linear‐chain nylon‐6. A wide‐angle X‐ray diffraction study indicated that the crystal structure of the star‐shaped nylon‐6 still belonged to the α form, and the crystallizability of the branched polymer with an elevated amount of trimesinic acid during polymerization did not seem to be weakened; the characteristic absorption of infrared spectra provided indirect evidence for the existence of branched chains in the polymer. Moreover, the mechanical properties of star‐shaped nylon‐6 and linear‐chain nylon‐6 were compared. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3184–3193, 2001
Study on the preparation and properties of styrene–butyl acrylate–silicone copolymer latices
Authors: Kan Cheng You , Liu De Shan , Kong Xiang Zheng , Zhu Xiao Li
Published: October 2004

Copolymer latices of styrene–butyl acrylate–silicone were prepared using a semicontinuous addition process and batch and monomer emulsion addition processes. The results showed that a stable latex with narrow particle size dispersion and a high monomer conversion can be obtained only by the semicontinuous addition process. The simultaneous free‐radical and ionic copolymerization mechanisms were discussed. 3‐Methacryloyloxypropyl trimethoxysilane in this work was used as a coupling agent to form a chemical bond between vinyl polymer and polysiloxane. It was found that the copolymerization reaction and the properties of latex and latex film were obviously influenced by silicone content. When the silicone content was less than 25 wt %, copolymerization proceeded readily and a stable latex could be prepared. With increasing silicone content, monomer conversion, latex stability, film hardness, and tensile strength decreased, whereas the water resistance and impact strength increased. Results of Soxhlet extraction, silicon analysis, and dynamic mechanical properties of latex polymer confirmed the occurrence of copolymerization. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3194–3200, 2001
Melt spinning of metallocene catalyzed polypropylenes. II. As‐spun filament structure and properties
Authors: Bond Eric Bryan , Spruiell Joseph E.
Published: October 2004

The melt spinning of metallocene catalyzed isotactic polypropylene (miPP) resins was investigated. The as‐spun filament properties from six miPP resins were studied with melt flow rates (MFR) between 10 and 100, and a Ziegler–Natta catalyzed isotactic polypropylene (zniPP) resin with a MFR of 35 was studied for a comparison. Generally, as the molecular weight increased the filament density increased, the birefringence decreased, the tensile strength decreased, and the elongation to break increased. As the spinning speed increased, the density, birefringence, tensile strength, and crystalline and noncrystalline orientation functions generally increased. However, the low MFR miPP and the zniPP resin had decreases in the birefringence and tensile strength with an increase of the spinning speed. The miPP resins were found to have breaking tensile strengths up to 50% higher than the zniPP resin at similar spinning speeds. The observed fiber properties were explained based on the nature and orientation of noncrystalline portions of the fibers. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3237–3247, 2001
Synthesis of polyferrocenyldimethylsilane through ring‐open polymerization and its electrochemical properties in different mediums
Authors: Wang L. , Ye C. Y. , Zhang P. Y. , Pan J. , Feng Linxian , Wang S. F. , Peng T. Z.
Published: October 2004

Polyferrocenyldimethylsilanes with different molecular weights were prepared via thermal ring‐opening polymerization of the corresponding strained, silicon‐bridged ferrocenophanes. The electrochemical behavior of the resultant polymers in different media were investigated by cyclic voltammetry. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3258–3261, 2001
Mechanism of fire retardancy of polyurethanes using ammonium polyphosphate
Authors: Duquesne Sophie , Le Bras Michel , Bourbigot Serge , Delobel René , Camino Giovanni , Eling Berend , Lindsay Chris , Roels Toon , Vezin Hervé
Published: October 2004

In this work, we studied the mechanism of the fire retardancy of ammonium polyphosphate (APP) in polyurethane (PU). Indeed, according to the limiting oxygen index test, the efficiency of APP in PU coating was proven. On the one hand, thermogravimetric analyses showed that the addition of APP to PU accelerates the decomposition of the matrix but leads to an increase in the amount of high‐temperature residue, under an oxidative or inert atmosphere. This stabilized residue acts as a protective thermal barrier during the intumescence–fire retardancy process. On the other hand, spectroscopic analysis of the charring materials using infrared spectroscopy, MAS NMR of the solid state, and ESR enables better understanding of the carbonization process and, consequently, of the intumescence phenomenon. It has been shown that the char resulting from PU consists of an aromatic carbonaceous structure which condenses and oxidizes at high temperature. In the presence of APP, a reaction between the additive and the polymer occurs, which leads to the formation of a phosphocarbonaceous polyaromatic structure. Moreover, this char is strongly paramagnetic. The presence of large radical species, such as a polyaromatic macromolecule trapping free radicals, was demonstrated. Both of these characteristics help to explain the fire‐retardant performance of PU/APP. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3262–3274, 2001
Temperature and crystallinity profiles generated in a polycaprolactone/starch blend under different cooling conditions
Authors: Ruseckaite R. A. , Stefani P. M. , Cyras V. P. , Kenny J. M. , Vázquez A.
Published: October 2004

This work concerns the numerical simulation of the temperature profiles and the degree of crystallinity through the thickness of a part made from a commercial biodegradable material based on caprolactone and starch (Mater‐Bi Z), as a function of the cooling conditions from the melt. The crystallization kinetics during cooling conditions was evaluated experimentally by calorimetry and the Kamal–Chu equation was used to describe the degree of crystallinity developed during constant cooling rate experiments. This equation coupled with the thermal energy equation, through a heat source term, described the heat generated during crystallization of the polymer. The numerical solution of the system of differential equations was obtained using an implicit finite‐difference method. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3275–3283, 2001
Modeling of degradation of unstabilized and HALS‐stabilized LDPE films under thermo‐oxidation and natural weathering conditions
Authors: Kaci M. , Sadoun T. , Moussaceb K. , Akroune N.
Published: October 2004

Mathematical models are proposed to predict degradation of unstabilized low density polyethylene (LDPE) films and those stabilized with hindered amine light stabilizers (HALS) under both thermo‐oxidation at 90°C and natural weathering conditions. The degradation was measured by change in percent elongation at break (ϵr) with time. The mathematical approach developed was multiple linear regression analysis (MLRA). The reliability of the selected models was analysed using four statistical criteria, residual variance, coefficient of determination (r2), Student test and Fisher‐Snedecor test. The linear systems that resulted from the MLRA were resolved by the Cholesky method. The results obtained indicated that the polynomial models developed to predict elongation at break were reliable for both unstabilized and HALS‐stabilized samples under thermo‐oxidation at 90°C and natural weathering conditions. This was also confirmed by the comparison of the half‐life time (HLT) values predicted from the models with those observed experimentally. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3284–3292, 2001
In situ compatibilized SAN/LCP blends through reactive copolymers
Authors: Huang Jieh‐Ming , You Min‐Feng , Chang Feng‐Chih
Published: October 2004

Styrene–acrylonitrile–glycidyl methacrylate (SAG) copolymers with various contents of glycidyl methacrylate (GMA) were used to compatibilize the incompatible blends of styrene–acrylonitrile (SAN) and a liquid crystalline polymer (LCP). These SAG copolymers contain reactive glycidyl groups that are able to react with the carboxylic acid and/or hydroxyl end groups of the LCP to form the SAG‐g‐LCP copolymers during melt processing. The in situ–formed graft copolymers tend to reside along the interface to reduce the interfacial tension and to increase the interface adhesion. The morphologies of the SAN/LCP blends were examined by using scanning electron microscopy (SEM), where the compatibilized SAN/LCP blends were observed with greater numbers and finer fibrils than those of the corresponding uncompatibilized blends. The mechanical properties of the blends increased after compatibilization. The presence of a small amount (200 ppm) of ethyl triphenylphosphonium bromide (ETPB) catalyst further promotes the graft reaction and improves the compatibilization. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3321–3332, 2001
Curing kinetic of the epoxy system badge n = 0/1,2 DCH by fourier transform infrared spectroscopy (FTIR)
Authors: Fraga F. , Burgo S. , Núñez E. Rodríguez
Published: October 2004

The curing reaction of an epoxy system consisting of a diglycidyl ether of bisphenol A (BADGE n = 0) and 1,2‐diaminocyclohexane (DCH) was studied by Fourier Trasform Infrared Spectroscopy (FTIR). From the infrared spectra using a peak‐height method, that was based on the ratio of the height of the characteristic to reference absorbance peak, degree of conversion at different isothermal temperatures were calculated. From a kinetic study, the Horie et al. model was used; parameters such as rate constants and activation energies were determined. The results were compared to those obtained for same epoxy systems using scanning differential calorimetry (DSC). © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3366–3372, 2001
Synthesis, structure, and characterization of polymeric stationary phase derived from (R,R)‐tartramide and bisphenol‐S
Authors: Jabłońska‐Pikus T. , Charmas W. , Podkościelna B. , Gawdzik B.
Published: October 2004

The preparation of a new chiral polymeric stationary phase for chromatography is presented. A porous copolymer of mono‐ and dimethacrylate derivatives of bisphenol‐S and divinylbenzene containing hydroxyl functional groups was used as a matrix. (3‐Aminopropyl)triethoxysilane was used as a coupling agent and was bonded to these groups. The obtained compound was transferred into a final product during a three‐step synthesis. The properties of the obtained polymeric phase with the chiral moiety were studied. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3409–3417, 2001
Thermal oxidation kinetics for a poly(bismaleimide)
Authors: Colin X. , Marais C. , Verdu J.
Published: October 2004

The thermal oxidation of poly(bismaleimide) of the F655‐2 type, supplied by Hexcel‐Genin, was studied by isothermal gravimetry at 180, 210, and 240°C and various oxygen pressures ranging from 0 to 1.2 bar. Comparison of various sample thicknesses and visible microscopy observations on bulk aged samples shows that the whole oxidized layer has a depth of about 75 μm at 240°C, 138 μm at 210°C, and 229 μm at 180°C. An attempt was made to build a kinetic model to predict this depth. It is based on a differential equation in which O2 diffusion and its consumption rate, r(C), are coupled, C being the O2 concentration. Its resolution needs two sets of experiments: the first one to determine the O2 diffusivity and solubility in the polymer, and the second one to determine r(C). The mathematical form of r(C) is derived from a mechanistic scheme of radical chain oxidation in which initiation is mainly due to POOH decomposition. This expression contains two kinetic parameters, α and β, the values of which are determined from the experimental curves of mass loss rate against O2 pressure (in the stationary state). The theoretical predictions, at each temperature under consideration, are in excellent agreement with experimental results. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3418–3430, 2001
Isothermal and nonisothermal crystallization of poly(aryl ether ketone ketone) with all‐para phenylene linkage
Authors: Wang Jiku , Yang Xiaoniu , Li Gao , Zhou Enle
Published: October 2004

Isothermal and nonisothermal crystallization behavior for PEKK(T) was studied using differential scanning calorimetry (DSC), transmission electron microscopy (TEM), and electron diffraction (ED). In the isothermal crystallization process, the Avrami parameters obtained were n = 2.33–2.69, which shows crystal growth of two‐dimensional extensions consistent with our observations by TEM. The lamellar thickness increases with the crystallization temperature of PEKK(T) crystallized isothermally from the melt. However, for the nonisothermal crystallization of PEKK(T), the results from the modified Avrami analysis show two different crystallization processes. Avrami exponents n1 = 3.61–5.30, obtained from the primary crystallization process, are much bigger than are the secondary n2 = 2.26–3.04 and confirmed by the observation of the spherulite morphology. PEKK(T) crystallized isothermally from the melt possesses the same crystal structure (Form I) as that from nonisothermal melt crystallization. The results from TEM observation show that the spherulite radius decreases with an increasing cooling rate. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3431–3438, 2001
Synthesis and characterization of poly{hexakis[(methyl)(4‐hydroxyphenoxy)]cyclotriphosphazene}
Authors: Luther Thomas A. , Stewart Frederick F. , Lash Robert P. , Wey John E. , Harrup Mason K.
Published: October 2004

The reaction of methylhydroquinone with hexachlorocyclotriphosphazene in the presence of a base, 4‐picoline, in cyclohexane was investigated. Nuclear magnetic resonance spectroscopy, multiangle laser light scattering, and elemental analyses were performed on the product and two other related phosphazene materials produced by analogous synthetic routes: poly[hexakis(4‐hydroxyphenoxy)cyclotriphosphazene] (1) and hexakis[(3‐tert‐butyl)(4‐hydroxyphenoxy)]cyclotriphosphazene (2). Unlike the data for 2 where the tert‐butyl moiety enforced regiospecific nucleophilic addition, the data for the methylhydroquinone‐substituted cyclotriphosphazene product indicate that the less sterically bulky methyl group provides only limited protection for the adjacent hydroxyl group. The result is the formation of a low molecular weight oligomer, poly{hexakis[(methyl)(4‐hydroxyphenoxy)]cyclotriphosphazene} (3), instead of a discrete cyclic trimer species. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3439–3446, 2001
High‐density polyethylene modified by polydimethylsiloxane
Authors: Muñoz P. MA. Patricia , Vargas Márcio D. , Werlang Moisés M. , Yoshida I. Valéria P. , Mauler Raquel S.
Published: October 2004

High‐density polyethylene (HDPE) was modified by the grafting of polydimethylsiloxane (PDMS) through a free‐radical process, in a melt‐mixer chamber, using dicumyl peroxide (DCP) as an initiator. The influence of PDMS (0.2–0.8 mol %) and peroxide (0.03–0.08 mol %) concentrations on the grafting, final torque, and melt flow rate (MFR) of copolymers were investigated using factorial planning. Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), gel permeation chromatography (GPC), MFR, and rheometry were used to characterize the copolymers obtained. Surface plots showed that higher degrees of grafted PDMS and higher final torques were obtained with increase in the PDMS amount at low DCP levels and with increase in the DCP amount at low PDMS levels. The peaks of fusion and crystallization of the copolymers showed no significant changes with respect to HDPE. Data of MFR and GPC suggested that crosslinking reactions and/or chain extension occurred concomitant with the grafting reactions. Copolymers with high grafting degrees showed high MFR and low dynamic shear viscosities in comparison with low grafting degree copolymers, which is probably due to the migration of the PDMS‐containing copolymers on the surface. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3460–3467, 2001
Hygrothermal aging of rubber modified and mineral filled dicyandiamide cured digylcidyl ether of bisphenol A epoxy resin. I. Diffusion behavior
Authors: Ivanova Katya I. , Pethrick Richard A. , Affrossman Stanley
Published: October 2004

The effect of hydration–dehydration cycling on the properties of a rubber modified, mineral filled epoxy resin is reported. This resin was based on diglycidyl ether of bisphenol A and cured with dicyandiamide. The material was aged in deionized water and a 5% (w/w) NaCl solution at 65°C. Gravimetric measurements, transmission electron microscopy, and diffusive reflectance IR Fourier transform spectroscopy were used to monitor the water sorption and physical and chemical changes occurring in the material. Two‐stage absorption was observed with deionized water, and the quasiequilibrium‐state water content was independent of the hygrothermal history. The equilibrium weight after dehydration depended on the hygrothermal history due to the presence of irreversibly absorbed water and leaching of material. The first stage of the absorption was found to be Fickian and was interpreted as being related to the process of saturation of the epoxy matrix. The driving force for the second stage was the osmotic pressure, and it was not observed when the material was aged in NaCl solution. The water caused irreversible damage to the resin through microcavity formation, and part of the water was molecularly dispersed in the epoxy matrix and part resided in microcavities. Absorption–desorption cycling resulted in an increased rate of absorption during subsequent rehydration. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3468–3476, 2001
Immobilization of cholesterol oxidase and potassium ferricyanide on dodecylbenzene sulfonate ion‐doped polypyrrole film
Authors: Kumar Arun , Rajesh  , Chaubey Asha , Grover S. K. , Malhotra B. D.
Published: October 2004

Dodecylbenzene sulfonate (DBS)‐doped polypyrrole (PPY) conducting polymer films were electrochemically deposited onto the indium‐tin‐oxide (ITO)‐coated glass plates in aqueous medium. The enzyme cholesterol oxidase (ChOx) was immobilized on these DBS–PPY films by a physical adsorption technique. These ChOx‐immobilized DBS–PPY films were characterized by ultraviolet–visible and Fourier transform infrared spectroscopy. The enzyme activity studies indicate that ∼40% of ChOx leaches out from the ChOx/DBS–PPY film. The ChOx activity in the ChOx/DBS–PPY film was assayed as a function of cholesterol concentration. The results of amperometric measurements conducted on ChOx/DBS–PPY/ITO film show linearity over the range 2–8 mM of cholesterol solution. The ChOx/DBS–PPY/ITO electrodes exhibit a response time of 30 s and are stable for ∼3 months at 4 °C. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3486–3491, 2001
Miscibility of polystyrene‐based ionomers with poly(2,6‐dibromo‐1,4‐phenylene oxide)
Authors: Alkan Cemil , Aras Leyla
Published: October 2004

Blends of poly(2,6‐dibromo‐1,4‐phenylene oxide) (PDBrPO) with 4.8 mol % sulfonated polystyrene (4.8SPS), Na‐neutralized 1.7 mol % sulfonated polystyrene (Na1.7SPS), Mn‐neutralized 3.8 mol % sulfonated polystyrene (Mn3.8SPS), and Zn‐neutralized 3.8 mol % sulfonated polystyrene (Zn3.8SPS) ionomers were investigated for their miscibilities with varying compositions by dilute solution viscometry (DSV), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC). Δb, μ, and α parameters by W. R. Krigbaum and F. J. Wall (J Polym Sci 1950, 5, 505), K. K. Chee (Eur Polym J 1990, 4, 423), and Z. Sun et al. (Eur Polym J 1992, 28, 1259), respectively, were calculated from DSV data to determine miscibility. Na1.7SPS is immiscible with PDBrPO in no relation to the blend compositions. On the other hand, the increasing extent of miscibility of the blends reflected by the data is as follows: 4.8SPS < Mn3.8SPS < Zn3.8SPS. DSC and SEM results are also in agreement with the DSV data except for the α parameter, which showed some disagreements with Δb and μ parameters in a few blends. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3558–3567, 2001
Physicochemical characterization of hydrogels based on polyvinyl alcohol–vinyl acetate blends
Authors: Cauich–Rodríguez J. V. , Deb S. , Smith R.
Published: October 2004

Hydrogels made of polyvinyl alcohol–vinyl acetate and its blends with water soluble polymer were studied in terms of swelling behavior, microstructure, and dynamic mechanical properties. Hydrogels prepared by blending polyvinyl alcohol–vinyl acetate with either polyacrylic acid or poly(4‐vinyl pyridine) exhibited a strong pH dependency. When poly(vinyl pyrrolidone) was used for blending, an unusual pH dependency was observed. An increase in the equilibrium water content in all systems resulted in an increase in the freezable water as determined by DSC. Critical point drying led to a striated surface on polyacrylic acid–polyvinyl alcohol–vinyl acetate hydrogels, whereas a porous structure was observed on the freeze‐dried poly(vinyl pyrrolidone)–polyvinyl alcohol–vinyl acetate gels. Hydrogels with elevated storage modulus were obtained when either polyvinyl alcohol–vinyl acetate alone or polyacrylic acid–polyvinyl alcohol–vinyl acetate blends were thermally treated at high temperatures (i.e., 150°C). Low storage modulus was observed for both poly(vinyl pyrrolidone) and poly(4‐vinyl pyridine)‐containing hydrogels. Temperature dependency of storage modulus from 20 to 60°C was observed only for poly(4‐vinyl pyridine)–polyvinyl alcohol–vinyl acetate hydrogels. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3578–3590, 2001
Phase segregation behavior in PE/DOP blends and glass‐transition temperatures of polyethylene
Authors: Shieh Yeong‐Tarng , Liu Chih‐Ming
Published: October 2004

Phase segregation behavior in PEs/DOP blends, interactions between PEs and DOP, and glass‐relaxation transitions of PEs were investigated. FTIR, DSC, and TGA data demonstrated that molecular interactions were present between PEs and DOP. DMA data demonstrated that pure PEs each (except HDPE) exhibited two loss maxima at about −20 and −120°C but the PEs/DOP blends (including the HDPE/DOP blend) yielded one new loss maximum at about −60°C. The glass‐relaxation transitions corresponding to the three loss maxima on the DMA curves were designated α (−20°C), β (−60°C), and γ (−120°C) transitions and were attributed to the relaxation of the amorphous phases in the interlamellar, interfibrillar, and interspherulitic regions, respectively, based on DMA, WAXD, SAXS, and POM measurements. The controversial Tg values of PEs and their origin were thus clarified in this study. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3591–3601, 2001
Growth and development of Encarsia formosa (Hymenoptera: Aphelinidae) in the greenhouse whitefly, Trialeurodes vaporariorum (Homoptera: Aleyrodidae): Effect of host age
Authors: Hu Jing S. , Gelman Dale B. , Blackburn Michael B.
Published: October 2004

The tiny parasitoid wasp, Encarsia formosa, has been used successfully to control greenhouse whiteflies (GHWFs) in greenhouses in many countries throughout the world. Therefore, there has been considerable interest in developing methods for artificially rearing this wasp. However, little information is available concerning the regulation of its development including the host‐parasitoid interactions that are required for the parasitoid to complete its life cycle. Here we confirm that parasitoid developmental rates differ significantly based upon the host instar parasitized. Development was faster when 3rd and 4th instar GHWFs were offered for parasitization than when 1st or 2nd instars were used. Our results show that it is primarily the embryo and the first two parasitoid instars that exhibit prolonged developmental times when 1st and 2nd instar whiteflies are parasitized. Although percent emergence was not affected by host age at the time of parasitization, adult longevity as well as adult emergence pattern varied greatly depending upon the instar parasitized. When 3rd and 4th instar GHWFs were selected for oviposition, adult wasps lived significantly longer than when 1st or 2nd instars were used; also, there was a sharp emergence peak on the 2nd day after emergence was first observed (reduced or absent when 1st or 2nd instar GHWFs were parasitized) and the emergence period was reduced from between 8 and 11 days to 5 days. In general, the younger the host instar parasitized, the less synchronous was parasitoid development. Previous reports that E. formosa will not molt to the 2nd instar until the host has reached its 4th instar were not confirmed. When 1st instar host nymphs were parasitized, 2nd instar parasitoids were detected in 3rd instar hosts. Importantly, however, no matter which instar was parasitized, the parasitoid never molted to its last instar until the host had reached Stage 5 of its last instar, a stage in which host pharate adult formation has been initiated. It appears, then, that a condition(s) associated with host pharate adult formation is required for the parasitoid’s final larval molt. Results reported here should facilitate the development of in vitro rearing systems for E. formosa.Arch. Insect Biochem. Physiol. 49:125–136, 2002. Published 2002 Wiley‐Liss, Inc.