bluuebunny/crossref_metadata_2025 huggingface dataset:
Processing thermal stability and degradation kinetics of poly(vinyl chloride)/montmorillonite composites
Authors: Wan Chaoying , Tian Guohua , Cui Ning , Zhang Yinxi , Zhang Yong
Published: March 2004

Thermal stability of polyvinyl chloride (PVC) based montmorillonite composites with either sodium montmorillonite (MMT) or alkyl ammonium ion modified montmorillonite (OMMT) were investigated by thermogravimetric analysis. The apparent activation energies associated with the first thermal degradation stage were calculated by the methods of Flynn–Wall–Ozawa and Kissinger in nitrogen atmosphere at several different heating rates. The processing thermal stability of PVC and PVC/MMT(OMMT) composites was also discussed. Increase of mixing torque did not result in a larger intercalation extent of PVC on MMT; instead, it unexpectedly induced discoloration of PVC and then deteriorated the processing stability, especially in the presence of OMMT. The apparent activation energies in the first thermal degradation stage exhibited little difference among PVC, PVC/MMT, and PVC/OMMT composites, and the kinetic compensation effect of Sp* kept a constant value, indicating that the thermal stability and thermal degradation mechanism of PVC were not affected by the presence of either MMT or OMMT, although the processing discoloration of PVC is observed for PVC/OMMT composite. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1521–1526, 2004
Studies on γ‐Fe2O3–high‐density polyethylene composites and their additives
Authors: Govindaraj B. , Sastry N. V. , Venkataraman A.
Published: March 2004

γ‐Fe2O3–high‐density polyethylene (HDPE) composite films are prepared by a gel‐casting technique. To understand the effect of additives, rice husk ash and thiourea are made to disperse in the HDPE matrix to obtain the composite films with additives. The as‐prepared γ‐Fe2O3–HDPE composite films with their additives are subjected to characterization and study through X‐ray diffraction, thermal, scanning electron microscopy, and dielectric measurements. The results are qualitatively treated. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1527–1533, 2004
Isotactic polypropylene microfiber prepared by carbon dioxide laser‐heating
Authors: Suzuki Akihiro , Narusue Shinichi
Published: March 2004

An isotactic polypropylene (i‐PP) microfiber was obtained by irradiating a carbon dioxide laser to previously drawn fibers. To prepare the thinner i‐PP microfiber, it is necessary to previously draw original i‐PP fibers under an applied tension of 7.8 MPa at a drawing temperature of 140°C. The drawn fiber was heated under an applied tension of 0.3 MPa using the laser operated at a power density of 39.6 W cm−2. The thinnest i‐PP microfiber obtained under optimum conditions had a diameter of 1.8 μm and a birefringence of 30 × 10−3. Its draw ratio estimated from the diameter reached 51,630. It is so far impossible to achieve such a high draw ratio by any drawing. The wide‐angle X‐ray diffraction photograph of the microfiber shows the existence of the oriented crystallites. Laser‐heating allows easier fabrication of microfibers compared with the conventional technology such as the conjugate spinning. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1534–1539, 2004
Synthesis and characterization of spinning poly(acrylonitrile‐co‐silk fibroin peptide)s
Authors: Chen Zhongmin , Suzuki Masahiro , Kimura Mutsumi , Kondo Yoshiyuki , Hanabusa Kenji , Shirai Hirofusa
Published: March 2004

A novel spinning acrylic polymer containing silk protein was synthesized by copolymerization of acrylonitrile (AN) and silk fibroin peptide (SFP) modified by acryloyl chloride (AC) with vinyl groups. From results of the examination to the chemical compositions, we established that the modified SFP is more reactive than AN in the copolymerization. The intrinsic viscosity values of these copolymers showed that the copolymers have good spinnability, which were synthesized under the condition of adding a trace of metal ions into the synthesizing solvent. These copolymers exhibited good thermal property. The fiber based on the poly(acrylonitrile‐co‐silk fibroin peptide) was prepared and characterized by SEM, FTIR measurement of its shell and core flakes, and moisture absorption. The fiber exhibited a smooth surface and could be assumed to have excellent adhesive property between SFP and PAN. Furthermore, these fibers showed a core–shell structure and excellent moisture absorption. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1540–1547, 2004
Rod‐climbing characteristics of α‐Fe2O3 suspended polyisobutylene/polybutene solution
Authors: Lim Sung T. , Choi Hyoung J. , Jhon Myung S.
Published: March 2004

From rod‐climbing rheometer measurements, we systematically investigated the normal stress values of suspended particles in polymeric liquids at low shear rates using the second‐order fluid constitutional relationship. The climbing constants β of the suspended α‐Fe2O3 particles in polyisobutylene/polybutene solutions, which exhibit Boger fluid characteristics (highly elastic, but no shear‐thinning), were estimated from the rod‐climbing experiment, showing that β increased with polymer concentration and polymer molecular weight. The first normal stress difference coefficient of the suspended α‐Fe2O3 in polymeric liquids obtained from the rod‐climbing rheometer was well correlated with the rheological properties measured by rotational rheometers. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1548–1552, 2004
Novel model for uniaxial strain‐rate–dependent stress–strain behavior of ethylene–propylene–diene monomer rubber in compression or tension
Authors: Song Bo , Chen Weinong , Cheng Ming
Published: March 2004

Based on quasi‐static and dynamic experimental results, a novel strain‐rate–dependent model for ethylene–propylene–diene monomer (EPDM) rubber was developed. This model, composed of a base model and rate‐sensitivity terms, has a relatively simple form to be embedded in computer codes for numerical simulations. The base model combines a Maxwell model and a Mooney function. The Maxwell model is necessary to describe small‐strain behavior, whereas the Mooney function dominates the large‐strain behavior. Each of these two components is then multiplied by a rate‐sensitive term to describe the material's strain‐rate sensitivities at both small and large strains. This model gives a good description of EPDM response in both compression and tension over a wide range of strain rates with a minimum number of material constants. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1553–1558, 2004
Partially miscible blends based on a polyarylate and poly(trimethylene terephthalate)
Authors: Guerrica‐Echevarria G. , Eguiazábal J. I. , Nazábal J.
Published: March 2004

The miscibility of blends of a polyarylate (PAr) with poly(trimethylene terephthalate) (PTT) was investigated in the whole composition range by DSC measurements. With the exception of the 90/10 composition, which was fully miscible, the blends showed partial miscibility, and contained a nearly pure PTT phase and a PAr‐rich phase with 18% PTT. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1559–1561, 2004
Study of the miscibility and crystallization behavior of poly(ethylene oxide)/poly(vinyl alcohol) blends
Authors: Lai Wei‐Chi , Liau Wen‐Bin
Published: March 2004

The miscibility and crystallization behavior of poly(ethylene oxide)/poly(vinyl alcohol) (PEO/PVA) blends were investigated by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and polarizing optical microscopy. Because the glass‐transition temperature of PVA was near the melting point of PEO crystalline, an uncommon DSC procedure was used to determine the glass‐transition temperature of the PVA‐rich phase. From the DSC and DMA results, two glass‐transition temperatures, which corresponded to the PEO‐rich phase and the PVA‐rich phase, were observed. It was an important criterion to indicate that a blend was immiscible. It was also found that the preparation method of samples influenced the morphology and crystallization behaviors of PEO/PVA blends. The domain size of the disperse phase (PVA‐rich) for the solution‐cast blends was much larger than that for the coprecipitated blends. The crystallinity, spherulitic morphology, and isothermal crystallization behavior of PEO in the solution‐cast blends were similar to those of the neat PEO. On the contrary, these properties in the coprecipitated blends were different from those of the neat PEO. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1562–1568, 2004
Grafting of polyacrylonitrile onto guar gum under microwave irradiation
Authors: Singh Vandana , Tiwari Ashutosh , Tripathi Devendra Narayan , Sanghi Rashmi
Published: March 2004

Using microwave (MW) irradiation grafting of polyacrylonitrile (PAN) onto guar gum in water was done without using any radical initiator or catalyst within a very short reaction time. The extent of grafting could be adjusted by controlling the reaction conditions and maximum percentage grafting (%G) of about 188% was obtained under optimum conditions in 1.66 min. The average molecular weight of the grafted PAN chains and water‐retention power of the alkali hydrolyzed MW‐grafted gums were also determined and compared with those of the conventionally synthesized (cs) graft copolymer. A representative MW‐grafted copolymer, guar‐g‐polyacrylonitrile was characterized by IR, NMR, XRD, TGA, and elemental analysis. A plausible mechanism for the grafting under MW was proposed. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1569–1575, 2004
Selection of a precursor of a monofunctional polyhedral oligomeric silsesquioxane reacted with aromatic diamines
Authors: Ramírez C. , Vilariño J. M. L. , Abad M. J. , Barral L. , Bouza R. , Cano J. , Díez F. J. , García‐Garabal S. , López J.
Published: March 2004

With the aim of selecting a precursor of a polyhedral oligomeric silsesquioxane (POSS) reacted with aromatic diamines for its incorporation into an epoxy network, to generate an organic–inorganic hybrid material containing POSS, a polyhedral oligomeric silsesquioxane (glycidylisobutyl–POSS) was reacted with the diamines 4,4′‐methylenebis(2,6‐diethylaniline) (MDEA), 4,4′‐diaminediphenylmethane (DDM), and 4,4′‐(1,3‐phenylenediisopropylidene)bisaniline (BSA), at 160°C and different times, in a proportion rich in amines. The distribution of species in the reaction was followed by gel permeation chromatography (GPC). From the experimental data obtained the selected precursor was POSS/BSA reacted at 160°C for 20 or 30 min, to ensure that all the POSS was reacted, that there was a maximum of the monosubstituted amines, and that there was no degradation. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1576–1583, 2004
Studies of adsorption properties of crosslinked chitosan for vanadium(V), tungsten(VI)
Authors: Qian Shahua , Wang Haoyun , Huang Ganquan , Mo Shaobo , Wei Wu
Published: March 2004

In this article, the adsorption properties of crosslinked chitosan (CCTS) for V(V) and W(VI) were studied. Experimental results showed the adsorption rates of CCTS for V(V) and W(VI) were closely related to the acidity of solution. The adsorption rates were 97% for V(V) at pH 4.0 and 96% for W(VI) at pH 4.5. The adsorption balance times, adsorption capacities, and adsorption mechanism were explored. This research is of significance for removal of V(V) and W(VI) in industrial wastewater and their preconcentration in trace analysis. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1584–1588, 2004
Surface grafting of polyacrylamide from polyethylene‐based copolymer film
Authors: Luo Ning , Husson Scott M. , Hirt Douglas E. , Schwark Dwight W.
Published: March 2004

Atom transfer radical polymerization (ATRP) was used to grow polyacrylamide from the surface of ethylene–acrylic acid copolymer (EAA) film. The surface functionalization constituted initiator immobilization and surface graft polymerization. All reaction steps were conducted at 24 ± 3°C; polymerization was done in aqueous solution. For initiator immobilization, the carboxylic acid groups on EAA film were converted to acid chloride groups; further reaction with ethanolamines gave hydroxyl groups onto which 2‐bromoisobutyryl bromide initiator was attached. ATR‐FTIR data indicated that 1.64 ± 0.09 times higher initiator density was achieved by using diethanolamine, relative to ethanolamine. Acrylamide monomer was polymerized from the initiator by ATRP to yield nondistorted, transparent films with polymerization times of up to 1 h. For films prepared using diethanolamine, 1 h polymerization time reduced the static water contact angle by more than 50°, significantly increasing the hydrophilicity of the film surface. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1589–1595, 2004
Studies on poly(acrylic acid)/attapulgite superabsorbent composite. I. Synthesis and characterization
Authors: Li An , Wang Aiqin , Chen Jianmin
Published: March 2004

A novel poly(acrylic acid)/attapulgite superabsorbent composite was synthesized by graft copolymerization reaction of acrylic acid (AA) on attapulgite micropowder using N,N′‐methylenebisacrylamide (MBA) as a crosslinker and ammonium persulfate (APS) as an initiator in aqueous solution. The effects on water absorbency of such factors as reaction temperature, initial monomer concentration, degree of neutralization of AA, amount of crosslinker, initiator, and attapulgite were investigated. These crosslinked superabsorbent composites were characterized by thermogravimetetric analysis and scanning electron microscopy. The graft copolymerization reaction of AA on attapulgite micropowder was characterized by FTIR. The water absorbencies for these superabsorbent composites in water and saline solutions were investigated and water‐retention tests were carried out. Results obtained from this study show that the water absorbency of the superabsorbent composite synthesized under optimal synthesis conditions with an attapulgite content of 10% exhibited an absorption of 1017 g H2O/g sample and 77 g H2O/g sample in distilled water and in 0.9 wt % NaCl solution, respectively. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1596–1603, 2004
Processing and chemorheology of epoxy resins and their blends with dendritic hyperbranched polymers
Authors: Ratna D. , Varley R. , Simon G. P.
Published: March 2004

Toughened epoxy systems have found increasing applications in automotive, aerospace, and electronic packaging industries. The present article reported work done for elucidation of gelation and vitrification for various epoxy systems and their blends with dendritic hyperbranched polymers (HBPs) having epoxy and hydroxyl functionality. Gel time was found to increase with increasing functionality from diglycidyl ether of bisphenol A (DGEBA) to tetraglycidyl diaminodiphenyl methane (TGDDM). The vitrification point was clearly identified from rheological experiments for triglycidyl p‐amino phenol (TGAP) and TGDDM. In the case of DGEBA a clear display of vitrification was not observed. TGDDM underwent vitrification sooner than did TGAP. Hydroxyl‐functionalized HBP reduced the gel time of the blends because of the accelerating effect of –OH groups to the epoxy curing reaction. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1604–1610, 2004
Preparation of positive‐temperature coefficient heaters using platinum‐catalyzed silicone rubber
Authors: Park Eun‐Soo , Yun Sung‐Jin , Kim Gwang‐Tae , Park Ill‐Joon , Choi Won‐Hyuck , Jeong Ji‐Woong , Hong Sung‐Young , Park Hyun‐Woo , Jang Lee Wook , Yoon Jin‐San
Published: March 2004

Various output heaters were extruded with acetylene black–filled platinum‐catalyzed silicone rubber. The resistivity–temperature behavior of extruded heaters exhibited a positive‐temperature coefficient (PTC) effect without any negative‐temperature coefficient (NTC) effect. Resistivity and thermal reproducibility of the extruded heaters were investigated during heating and cooling cycles at an applied voltage of 220 V. These heaters initially showed poor reproducibility of resistivity during the repeated cycles and this effect increased significantly as the acetylene black content decreased. PTC effect and electrical reproducibility were improved significantly during the thermal ageing process. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1611–1617, 2004
Synthesis of superabsorbent resin by ultraviolet photopolymerization
Authors: Ruan Weiqing , Qiao Jinliang , Huang Yuli , Niu Aijie
Published: March 2004

Synthesis of superabsorbent resin (SAR) was achieved by a new method, that of direct UV photopolymerization, and in particular the synthesis of a SAR of acrylic acid–potassium acrylate copolymer by UV photopolymerization was investigated. Influences of ratio (mol) of acrylate monomer to acrylic acid monomer, photoinitiators, crosslinking agents, and exposure time of UV light on the water‐absorbent properties were investigated. The results showed that the water absorbency (Q) of SAR based on Irgacure 1700 or Irgacure 1800 was 545–530 mL/g, but under the same conditions Q was 450 mL/g for the SAR based on Irgacure 651. N,N′‐Methylene bisacrylamide, hydroethyl acrylate, and glycerol were used as crosslinking agents, of which N,N′‐methylene bisacrylamide was the most effective. It crosslinked the molecular chains through attending the copolymerization with acrylic acid (AA) and potassium acrylate. When the exposure time was 5 min, the value of Q was 1368 mL/g (the content of N,N′‐methylene bisacrylamide was 100 ppm). © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1618–1624, 2004
Syntheses and adsorption properties for Hg2+ of chelating resin of crosslinked polystyrene‐supported 2,5‐dimercapto‐1,3,4‐thiodiazole
Authors: Qu Rongjun , Wang Chunhua , Sun Changmei , Ji Chunnuan , Cheng Guoxiang , Wang Xiaoqin , Xu Gang
Published: March 2004

A novel chelating resin with functional group containing S and N atoms was prepared using chloromethylated polystyrene and 2,5‐dimercapto‐1,3,4‐thiodiazole (also called bismuththiol I, BMT) as materials. Its structure was characterized by infrared spectra and elementary analysis. The results showed that the content of the functional group was 2.07 mmol BMT g−1 resin, 47% of which were in the form of monosubstitution (PS‐BMT‐1) and 53% in the form of double substitution (PS‐BMT‐2). The adsorption for mercury ion was investigated. The adsorption dynamics showed that the adsorption was controlled by liquid film diffusion. Increasing the temperature was beneficial to adsorption. The Langmuir model was much better than the Freundlich model to describe the isothermal process. The adsorption activation energy (Ea), ΔG, ΔH, and ΔS values calculated were 18.56 kJ·mol−1, ‐5.99 kJ·mol−1, 16.38 kJ·mol−1, and 37.36, J·mol−1·K−1, respectively. The chelating resin could be easily regenerated by 2% thiourea in 0.1 mol·L−1 HCl with higher effectiveness. Five adsorption–desorption cycles demonstrated that this resin was suitable for repeated use without considerable change in adsorption capacity. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1646–1652, 2004
Thermal mechanical and dynamic mechanical property of biphenyl polyimide fibers
Authors: Zhang Qing‐Hua , Luo Wei‐Qiang , Gao Lian‐Xun , Chen Da‐Jun , Ding Meng‐Xian
Published: March 2004

High‐performance polyimide fibers possess many excellent properties, e.g., outstanding thermal stability and mechanical properties and excellent radiation resistant and electrical properties. However, the preparation of fibers with good mechanical properties is very difficult. In this report, a biphenyl polyimide from 3,3′,4,4′‐biphenyltetracarboxylic dianhydride and 4,4′‐oxydianiline is synthesized in p‐chlorophenol by one‐step polymerization. The solution is spun into a coagulation bath of water and alcohol via dry‐jet wet‐spinning technology. Then, the fibers are drawn in two heating tubes. Thermal gravimetric analysis, thermal mechanical analysis, and dynamic mechanical analysis (DMA) are performed to study the properties of the fibers. The results show that the fibers have a good thermal stability at a temperature of more than 400°C. The linear coefficient of thermal expansion is negative in the solid state and the glass transition temperature is about 265°C. DMA spectra indicate that the tanδ of the fibers has three transition peaks, namely, α, β, and γ transition. The α and γ transition temperature, corresponding to the end‐group motion and glass transition, respectively, extensively depends on the applied frequency, while the β transition does not. The activation energy of α and γ transition is calculated using the Arrhenius equation and is 38.7 and 853 kJ/mol, respectively. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1653–1657, 2004
Use of pyrolysed oil shale as filler in poly(ethylene‐co‐vinyl alcohol)
Authors: Vasconcelos Barbosa Ronilson , Baumhardt‐Neto Ricardo , Santos Mauler Raquel , José Carlos , Gorga Perez , Gazzana Schneider Cláudia
Published: March 2004

The pyrolysed oil shale (POS) obtained from the pyrolysis of bituminous rock was used as filler in poly(ethylene‐co‐vinyl alcohol) (EVAL). The effects of vinyl alcohol content in the EVAL and the particle size of pyrolysed oil shale in the mechanical properties were investigated. The EVAL was prepared by hydrolysis of poly(ethylene‐co‐vinyl acetate) (EVA) with 8 and 18 wt % of vinyl alcohol content. The composites were prepared in a rotor mixer at 180°C with concentration of pyrolysed oil shale up to 5 wt %. Stress–strain plots of compression‐molded composites showed a synergic behavior in the mechanical properties for low concentrations (1–5 wt %) of POS in all particle sizes and EVAL used. Such behavior indicates a close packing and strong interactions between the inorganic filler and the polymer. Increasing of the vinyl alcohol content of EVAL improved the compatibility between the polymer and filler, but decreasing the POS particle size had no effect on the properties. The modulus and the ultimate tensile strength also increased in all concentrations of POS for both EVAL. Mechanical properties and dynamic mechanical analysis also demonstrated the compatibility between EVAL and POS. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1658–1665, 2004
Preparation and properties of unsaturated polyester–montmorillonite intercalated hybrid
Authors: Zhang Yonghua , Cai Qingyi , Jiang Zhijie , Gong Kecheng
Published: March 2004

An unsaturated polyester–organophilic montmorillonite hybrid was prepared by dispersing polymerizable quaternary ammonium‐modified montmorillonite in an unsaturated polyester resin, followed by cross‐linking reaction. The purpose of this investigation was to discover the role of the polymerizable group of quaternary ammonium in improving interfacial interaction between the silicate layers and polymer chains and the mechanical properties of unsaturated polyester–montmorillonite hybrids. It is found that when the content of organophilic montmorillonite is between 2 and 5%, the tensile strength, impact strength, heat resistance, and swelling resistance of the hybrid are obviously enhanced and are better than that of the composites prepared with pristine or nonpolymerizable quaternary ammonium‐modified montmorillonite. Results of X‐ray diffraction and transmission electron microscopy show that unsaturated polyester and styrene in the resin can be intercalated into the interlayer space of organophilic montmorillonites. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2038–2044, 2004
Modification of polystyrene by reactive extrusion with peroxide and trimethylolpropane triacrylate
Authors: Kyu Kim Byung , Ho Shon Kyung , Mo Jeong Han
Published: March 2004

Polystyrene (PS) was modified by reactive extrusion with trimethylolpropane triacrylate (TMPTA) and dicumyl peroxide (DCP). The coupling reaction caused by TMPTA increased the molecular weight of PS, and this coupling reaction was enhanced in the presence of DCP at high TMPTA/DCP ratio. The rheological properties of the extrudate were examined. The impact strength of PS improved as the molecular weight increased by the coupling reaction. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1672–1679, 2004
Crystallization and melting behavior of 1,2‐syndiotactic polybutadiene
Authors: Bertini Fabio , Canetti Maurizio , Ricci Giovanni
Published: March 2004

1,2‐Syndiotactic polybutadiene was synthesized at −30°C using the catalyst system CrCl2(dmpe)2‐MAO. The syndiotactic index of the butadiene sequences, expressed as a percentage of syndiotactic pentads [rrrr], was evaluated by 13C‐NMR measurements. WAXD and SAXS techniques were employed to characterize the crystalline structure of the polymer. The thermal behavior of the polybutadiene was investigated by differential scanning calorimetry. The isothermal crystallization kinetics were described by means of the Avrami equation, which suggested a three‐dimensional growth of crystalline units, developed by heterogeneous nucleation, followed by a secondary crystallization stage. Polybutadiene isothermally crystallizes from the melt according to regime II of crystallization described by Lauritzen–Hoffman secondary nucleation theory. Nonisothermal crystallization kinetics were elaborated using the Ziabicki and Avrami methods modified by Jeziorny. The equilibrium melting temperature was calculated. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1680–1687, 2004
Surface modification of ethylene‐co‐acrylic acid copolymer films: Addition of amide groups by covalently bonded amino acid intermediates
Authors: Luo Ning , Stewart Michael J. , Hirt Douglas E. , Husson Scott M. , Schwark Dwight W.
Published: March 2004

Amide groups were anchored covalently on the surface of ethylene‐co‐acrylic acid (EAA) copolymer film by surface grafting of amino acid intermediates. The process consisted of four steps: conversion of carboxylic acid groups on the EAA surface to acid chloride groups, amino acid attachment, conversion of amino acid carboxyl groups to acid chloride groups, and amidation. All steps were carried out at room temperature. ATR‐FTIR spectroscopy was used to characterize the film after each step and to measure the kinetics of amino acid attachment. Three amino acids were studied: 12‐aminododecanoic acid (12‐ADDA), 5‐aminophthalic acid (5‐APA), and L‐aspartic acid (AA). The longer‐chain 12‐ADDA compound was selected for its chemical similarity to migratory fatty amides that are commonly used to alter the frictional behavior of polyolefin films. The 5‐APA and AA compounds were selected because each has two carboxylic acid groups that can be converted to amide groups. After amidation, the modified EAA films were characterized by static water contact angle measurements and scanning probe microscopy. Results showed that the 12‐ADDA reacted to the surface much faster than the 5‐APA or AA. Several steps of aggressive rinsing confirmed that the 12‐aminododecanamide was chemically anchored onto the EAA surface. As a result, both hydrophilicity and surface roughness were increased. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1688–1694, 2004
Preparation of silane‐terminated polystyrene and polymethylmethacrylate self‐assembled films on silicon wafer
Authors: Zhou Feng , Liu Weimin , Xu Tao , Liu Shujuan , Chen Miao , Liu Jianxi
Published: March 2004

End silane functionalized polystyrene and polymethylmethacrylate were prepared through radical chain‐transfer reaction and characterized with gel‐permeation chromatography. The chain‐transfer constants of mercaptopropyltrimethoxysilane for the polymerization of styrene and methylmethacrylate were determined to be 8.48 and 0.67, respectively, from the slopes of 1/DPn versus [S]/[M] lines. The ultrathin films of the end silane–terminated polymers were prepared by self‐assembly onto hydroxylated silicon wafers. The water contact angle on the resulting ultrathin films and the film thickness were measured. The morphology and chemical features of the films were observed and investigated by means of atomic force microscopy and X‐ray photoelectron spectroscopy. Results indicated that the chain‐transfer agent played a key role in making it possible for the silane‐terminated polystyrene and polymethylmethacrylate to be self‐assembled on Si(111), whereas the thickness and surface quality of the ultrathin films were dependent on the molecular weights of the polymers. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1695–1701, 2004
Structure and properties of polyamide 6 blends with low‐density polyethylene grafted by itaconic acid and with neutralized carboxyl groups
Authors: Pesetskii S. S. , Krivoguz Y. M. , Jurkowski B.
Published: March 2004

A comparative study of the structure and properties of two‐phase blends of polyamide 6 (PA6) and low‐density polyethylene (LDPE) modified in the course of reactive extrusion, by grafting of itaconic acid (IA) without neutralization of carboxyl groups (LDPE‐g‐IA) and with neutralized carboxyl groups (LDPE‐g‐IA−M+) was carried out. It was shown that 30 wt % of LDPE‐g‐IA−M+ introduced to PA6 resulted in blends of higher Charpy impact strength compared with that of PA6/LDPE‐g‐IA blends. The maximum increase was achieved when Mg(OH)2 was used as a neutralizing agent. The blend morphology has a two‐phase structure with blurred interphases because of increased adhesion between the phases. The neutralization of carboxyl groups in grafted IA did not lead to two‐phase morphology of blends, which had a negative influence on the mechanical properties. It is believed that the differences in the impact strength were caused by the influence of the added neutralizing agents on the structure of interphases, which depends on both the interfaces adhesion and structural effects resulting from the nucleating behavior of the neutralizing agent. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1702–1708, 2004
Preparation and characterization of sulfonated polyetherimide/polyetherimide blend membranes
Authors: Shen Li‐Qiang , Xu Zhi‐Kang , Yang Qian , Sun Hang‐Lin , Wang Shu‐Yuan , Xu You‐Yi
Published: March 2004

Polyetherimide (PEI) was sulfonated by chlorosulfonic acid (CSA) in 1,2‐dichloroethane for the first time. With the increase of the CSA/PEI repeat unit ratio and/or reaction time, the ion‐exchange capacity (IEC) of the sulfonated polyetherimide (SPEI) increased accordingly. Water‐uptake testing and contact‐angle measurement showed that the hydrophilicity of the SPEI increases with the increase of the IEC. Membranes were fabricated from SPEI/PEI blends with different ratios. The morphologies of the blend membranes were examined by scanning electron microscopy, which showed that the membrane pore size is larger when SPEI with higher IEC was used. With the increase of SPEI ratio in the blend membranes, the membrane pore size also increased. The contact‐angle data of the membranes showed that the hydrophilicity of the blend membrane was elevated because of the sulfonate group on the SPEI molecular backbone. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1709–1715, 2004
Preparation and characterization of starch/polycaprolactone blend
Authors: Kweon Dong‐Keon , Kawasaki Norioki , Nakayama Atsuyoshi , Aiba Seiichi
Published: March 2004

To make starch/polycaprolactone (PCL) blend with high miscibility, starch was chlorinated (starch‐Cl) by using methanesulfonylchloride (CH3SO2Cl) in dimethylformamide (DMF) prior to blending. Starch‐Cl/PCL blends were prepared by the mixing between starch‐Cl and PCL solutions under various conditions. To study the change of structure, thermal and physical characteristics of starch‐Cl/PCL blend, FTIR, DSC, SEM, and solvent resistance were measured. By blending starch‐Cl and PCL, a chemical reaction occurred partially in blend (FTIR result); thereby, the miscibility (DSC and SEM results) and solvent resistance were increased. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1716–1723, 2004
Surface hydrolysis of filaments based on poly(trimethylene terephthalate) spun at high spinning speeds
Authors: Kotek Richard , Jung Dong‐Wook , Kim Joon Ho , Smith Brent , Guzman Patricia , Schmidt Benjamin
Published: March 2004

The surface alkaline hydrolysis of fibers made from poly(trimethylene terephthalate) (PTT) was studied after extruding the polymer at high spinning speeds from 2000 to 6000 m/min and heat setting in the range of temperatures from 100 to 180°C. Fiber weight loss increased with an increasing heat‐setting temperature but it was also dependent on the spinning speed. Some of the partially hydrolyzed fibers had a well‐developed, hydrophilic surface, and pore size in the range of 0.69 to 1.20 μm. The optimum reaction and morphological conditions for increasing porosity in PTT fibers depends on spinning speed and heat‐setting temperature. A temperature of 180°C is the upper limit for heat‐setting PTT filaments but seems to be the most effective for making porous fibers. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1724–1730, 2004
Electrical/pH responsive properties of poly(2‐acrylamido‐2‐methylpropane sulfonic acid)/hyaluronic acid hydrogels
Authors: Kim Seon Jeong , Lee Chang Kee , Kim Sun I.
Published: March 2004

Poly(2‐acrylamido‐2‐methylpropane sulfonic acid) (PAMPS)/hyaluronic acid (HA) interpenetrating polymer network (IPN) hydrogels have been prepared by using the sequential‐IPN method. The IPN hydrogels exhibited swelling behavior in solutions at various pHs, in NaCl solutions, and under electrical DC stimulation. The IPN hydrogels were highly swollen in water, but lost much of their water capacity when transferred to solutions having a high ionic strength. The IPN hydrogels showed a significant responsive deswelling in an applied electric field. This behavior indicates the potential application of IPN hydrogels as biomaterials. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1731–1736, 2004
Thermal and thermooxidative degradation of engineering thermoplastics and life estimation
Authors: Gupta Y. N. , Chakraborty Amitabh , Pandey G. D. , Setua D. K.
Published: March 2004

This investigation deals with the thermal or thermooxidative degradation behavior of three engineering polymers [e.g., poly(ethylene terephthalate) (PET), poly(ether sulfone) (PES), and poly(ether ether ketone) (PEEK)] by using thermogravimetry‐coupled mass spectrometry (TG‐MS) analysis. The experiments were conducted both in argon and in air separately to study the changes in the degradation pattern of the polymers under varied sample environments. The samples were subjected to a programmed heating rate of 10°C/min and a temperature range from ambient to 800°C. For all these polymers, the decomposition rate, percentage weight loss, and the nature of the evolved gases were found to vary while changing the environment from argon to air. Methods of nonisothermal kinetic analysis, proposed by Flynn and Wall, and the shelf life estimation, proposed by Toop, have been described. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1737–1748, 2004
In situ polymerization of titanium isopropoxide in polycaprolactone: Properties and characterization of the hybrid nanocomposites
Authors: Wu Chin‐San
Published: March 2004

In this study, tetra isopropyl ortho titanate (TTIP) and polycaprolactone (PCL) were chosen as the ceramic precursor and the continuous phase, respectively, for the preparation of novel nanocomposites by using an in situ sol‐gel process. In addition, acrylic acid grafted polycaprolactone (PCL‐g‐AA) was investigated as an alternative to PCL. The hybrids (PCL/TiO2 and PCL‐g‐AA/TiO2) were characterized via Fourier transform infrared (FTIR) spectroscopy, dynamic mechanical thermal analysis (DMA), X‐ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetry analysis (TGA), and Instron mechanical testing. It was found that the carboxylic acid groups of acrylic acid acted as coordination sites for the titania phase to form chemical bonds, thus improving the properties of the acrylic acid grafted composite compared with its acrylic‐acid‐free counterpart. The TiO2 content also determined the strength of interfacial bonding between the polymer chains and the ceramic phase, as shown by changes in glass transition temperature (Tg) with TiO2 content. The maximum values of tensile strength and Tg were obtained with the PCL‐g‐AA/TiO2 composite at 10 wt % TiO2. At TiO2 contents above this, excess particles led to segregation between the organic and inorganic phases. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1749–1757, 2004
A governing equation for physical aging of thick and thin fluoropolyimide films
Authors: Zhou Chun , Chung Tai‐Shung , Wang Rong , Hong Goh Suat
Published: March 2004

An equation based on the segmental/chain mobility in free volume theory was derived to correlate the gas permeation coefficient and the aging time. An accelerated physical aging of a fluoropolyimide was observed and employed to validate this equation. A strong thickness‐dependent aging process was found by employing pure O2 and N2 tests to monitor the change of gas permeation properties as a function of aging time. Experimental results also suggest that chain rigidity and configuration play important roles in physical aging. As a result, the thin 2,2′‐bis(3,4′‐dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) based polyimide films studied here have different permeability versus time relationship from conventional polyarylate in the early stage of aging, and the experimental data seem to fit the proposed equation well. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1758–1764, 2004
Study on the macrokinetics of poly(trimethylene terephthalate) polycondensation reaction
Authors: Chen Kequan , Tang Xiaozhen , Chen Shangwei , Fu Gang
Published: March 2004

The macrokinetics of poly(trimethylene terephthalate) (PTT) polycondensation reaction during the high‐vacuum process was studied. The results showed that PTT polycondensation reaction may be considered as a second‐order reaction and thermal degradation is negligible in mathematical handling. The intrinsic viscosity versus time undergoes two different processes according to temperature. The apparent reaction rate constants and apparent activation energy of PTT polycondensation reaction are smaller than those of PET. Under efficient stirring, PTT polycondensation reaction is still reaction‐controlled and the role of devolatilization could be neglected even during the high‐vacuum process. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1765–1770, 2004
Interfacial effects in polypropylene–silica nanocomposites
Authors: Rong Min Zhi , Zhang Ming Qiu , Pan Shun Long , Friedrich Klaus
Published: March 2004

Grafted inorganic nanoparticles can greatly improve the mechanical performance of polymers. To examine the effects of the interfacial characteristics generated by the grafting polymer bonded to nanoparticle surfaces, we chemically grafted nano‐silica with different polymers and then melt‐mixed it with polypropylene (PP). We extracted the homopolymers produced during the graft polymerization from the grafted products before the composites were manufactured to get rid of the side effects of the nongrafting polymers. We tailored the interfacial interaction between the grafted nano‐SiO2and PP matrix by changing the amount of the grafting polymers on the nanoparticles, that is, the grafting percentage. Mechanical tests indicated that all the composites incorporated with grafted nano‐SiO2particles possessed much higher impact strength than untreated SiO2/PP composites and neat PP. The greatest contribution of the particles was made at a low grafting percentage. Tensile measurements showed that the treated nanoparticles could provide PP with stiffening, strengthening, and toughening effects at a rather low filler content (typically 0.8 vol %) because of the enhanced interfacial adhesion resulting from molecular entanglement and interdiffusion between the grating polymers on the nanoparticles and matrix macromolecules. The presence of grafting polymers on the nanoparticles provided the composites with a tailorable interphase. The tensile performance of the composites was sensitive to the nature of the grafting polymers. Basically, a hard interface was beneficial to stress transfer, whereas a soft one hindered the development of cavities in the matrix. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1771–1781, 2004
Morphological study of poly(vinylidene fluoride) asymmetric membranes: Effects of the solvent, additive, and dope temperature
Authors: Yeow M. L. , Liu Y. T. , Li K.
Published: March 2004

Asymmetric poly(vinylidene fluoride) (PVDF) membranes were cast with commercial‐grade Kynar K760 polymer pellets and four different solvent systems: N,N‐dimethylacetamide (DMAc), N,N‐dimethylformamide, 1‐methyl‐2‐pyrrolidone, and triethyl phosphate. With a focus on the PVDF/DMAc system, the effects of various additives (i.e., ethanol, glycerol, lithium chloride, lithium perchlorate, and water) on the resulting membrane morphology were investigated. The membrane morphology was examined with scanning electron microscopy. The effect of the dope solution temperature on the membrane morphology was also studied for the various additives used. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1782–1789, 2004
Effect of water on the oxygen barrier properties of poly(ethylene terephthalate) and polylactide films
Authors: Auras Rafael , Harte Bruce , Selke Susan
Published: March 2004

The aim of this work was to study the variations in the oxygen diffusion, solubility, and permeability coefficients of polylactide (PLA) films at different temperatures (5, 23, and 40°C) and water activities (0–0.9). The results were compared with the oxygen diffusion, solubility, and permeability coefficients obtained for poly(ethylene terephthalate) (PET) films under the same experimental conditions. The water sorption isotherm for PLA films was also determined. Diffusion coefficients were determined with the half‐sorption time method. Also, a consistency test for continuous‐flow permeability experimental data was run to obtain the diffusion coefficient with the lowest experimental error and to confirm that oxygen underwent Fickian diffusion in the PLA films. The permeability coefficients were obtained from steady‐state permeability experiments. The results indicated that the PLA films absorbed very low amounts of water, and no significant variation of the absorbed water with the temperature was found. The oxygen permeability coefficients obtained for PLA films (2–12 × 10−18 kg m/m2 s Pa) were higher than those obtained for PET films (1–6 × 10−19 kg m/m2 s Pa) at different temperatures and water activities. Moreover, the permeability coefficients for PLA and PET films did not change significantly with changes in the water activity at temperatures lower than 23°C. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1790–1803, 2004
Water‐swelling elastomer prepared by in situ formed lithium acrylate in chlorinated polyethylene
Authors: Ren Wentan , Peng Zonglin , Zhang Yong , Zhang Yinxi
Published: March 2004

Lithium acrylate (LiAA) was in situ prepared in a chlorinated polyethylene (CPE) matrix through the neutralization of lithium hydroxide (LiOH) and acrylic acid (AA) during mixing. The obtained compounds were vulcanized with dicumyl peroxide (DCP). The in situ preparation and polymerization of LiAA were characterized with Fourier transform infrared spectrometry. The crosslink density analysis results indicated that the CPE/LiAA vulcanizates contained both covalent bonds and ionic bonds. The effects of the DCP and LiAA contents on the mechanical properties and water‐swelling properties of the CPE/LiAA vulcanizates were studied. The relationship between the LiOH/AA molar ratio and the properties of the CPE/LiAA vulcanizates was investigated. The results showed that LiAA could improve the mechanical and water‐swelling properties of CPE/LiAA vulcanizates, providing a new approach to the preparation of water‐swelling elastomers. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1804–1812, 2004
Effect of surfactant systems on the water sensitivity of latex films
Authors: Butler Lauren N. , Fellows Christopher M. , Gilbert Robert G.
Published: March 2004

The effects of three different types of surfactant systems (ionic, polymeric, and electrosteric stabilizers) on the water sensitivity of poly(butyl acrylate‐co‐methyl methacrylate) latex films was examined. The water sensitivity was found to be strongly dependent on the surfactant system used in their preparation. A number of factors, such as the surfactant mobility and crystallinity and surfactant/polymer polarity appeared to affect the water uptake of the films. Highly mobile and crystallizable surfactants yielded high water sensitivity for films containing ionic surfactants, whereas the surfactant polarity had a greater effect on latices stabilized by polymeric surfactants, with the more hydrophilic systems providing greater water uptake. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1813–1823, 2004
Homopolymerization and copolymerization of tert‐butyl methacrylate and norbornene with nickel‐based methylaluminoxane catalysts
Authors: Huang Chih‐Feng , Wang Shih‐Kai , Kuo Shiao‐Wei , Huang Wu‐Jang , Chang Feng‐Chih
Published: March 2004

The homopolymerization and copolymerization of tert‐butyl methacrylate (tBMA) and norbornene (NB) with nickel(II) acetylacetonate in combination with methylaluminoxane were systematically investigated. This catalytic system showed high activity toward the homopolymerization of both NB and tBMA. For these copolymerizations, activity was gradually lost with an addition of tBMA to NB or of NB to tBMA. This result was qualitatively explained with the trigger coordination mechanism. Furthermore, the determination of the reactivity ratios indicated a significantly higher reactivity for NB than for tBMA (rNB = 4.14 and rtBMA = 0.097), and this was interpreted by the coordination mechanism. The synthesized acrylate/NB copolymers exhibited glass‐transition temperatures of 100–250°C. The absence of crystallinity and the homogeneous repartition of the monomer units along the main chain yielded products with high transparency and high stability © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1824–1833, 2004
Supercritical CO2 assisted processing of polystyrene/nylon 1212 blends and CO2‐induced epitaxy on nylon 1212
Authors: Chang Yuning , Xu Qun , Han Buxing , Wang Yudong , Liu Minying , Zhao Qingxiang
Published: March 2004

Polystyrene/nylon 1212 blends were prepared with supercritical CO2 as the substrate swelling agent and monomer/initiator carrier. Original nylon 1212 and blends were characterized with differential scanning calorimetry (DSC), polarizing microscopy, wide‐angle X‐ray diffraction, and scanning electron microscopy (SEM). A novel phenomenon, CO2‐induced epitaxy, was discovered, and its mechanism was deduced. Thermal analysis performed with DSC indicated that the polystyrene/nylon 1212 blends had thermal stability superior to that of virgin nylon 1212. The DSC and SEM measurements indicated that incorporated polystyrene could notably improve the mechanical performance of nylon 1212. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2023–2029, 2004