bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polyacrylamide–clay nanocomposite materials prepared by photopolymerization with acrylamide as an intercalating agent
Authors: Yeh Jui‐Ming , Liou Shir‐Joe , Chang Ya‐Wen 
Published: January 2004

AbstractA series of nanocomposite materials consisting of water‐soluble polyacrylamide (PAA) and layered montmorillonite (MMT) clay platelets were prepared by the effective dispersion of the inorganic nanolayers of the MMT clay in the organic PAA matrix via in situ ultraviolet‐radiation polymerization. The acrylamide monomers functioned as both the intercalating agent and the reacting monomers. As a representative procedure for the preparation of the nanocomposites, organic acrylamide monomers were first intercalated into the interlayer regions of acrylamide‐treated organophilic clay hosts, and this was followed by one‐step ultraviolet‐radiation free‐radical polymerization with benzil as a photoinitiator. The as‐prepared polyacrylamide–clay nanocomposite (PCN) materials were subsequently characterized by Fourier transform infrared spectroscopy, wide‐angle powder X‐ray diffraction, and transmission electron microscopy. The effects of the material composition on the thermal stability, optical clarity, and gas‐barrier properties of pristine PAA and PCN materials, in the forms of fine powders and membranes, were also studied by differential scanning calorimetry, thermogravimetric analysis, ultraviolet–visible transmission spectroscopy, and gas permeability analysis. The molecular weights of PAA extracted from PCN materials and pristine PAA were determined by gel permeation chromatography with tetrahydrofuran as an eluant. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3489–3496, 2004
Synthesis, characterization, and thermal properties of poly(methylvinylsilylene‐co‐styrene)
Authors: Ambadas G. , Packirisamy S. , Radhakrishnan T. S. , Ninan K. N. 
Published: January 2004

AbstractThe copolymerization of methylvinyldichlorosilane (MVDCS) and styrene was carried out with various monomer feed ratios under dechlorination conditions with sodium in toluene at 110°C. The copolymers were obtained in 84–95% yields. The copolymerization of MVDCS and styrene with monomer feed ratios of 1 : 0.25 and 1 : 0.5 mainly gave insoluble polymers. The copolymers synthesized with monomer feed ratios of 1 : 1, 1 : 3, and 1 : 7 contained soluble fractions of 3, 26, and 47%, respectively. The copolymers were characterized with infrared, 1H‐NMR, gel permeation chromatography, thermogravimetric analysis, pyrolysis/gas chromatography (PGC), X‐ray diffraction, and elemental analysis (silicon content). 1H‐NMR and PGC studies suggested that the soluble fractions were mainly polystyrene. PGC studies indicated that the copolymers obtained with monomer feed ratios of 1 : 0.25 and 1 : 0.5 did not have any significant amount of polystyryl blocks, whereas the copolymers obtained with higher styrene feed ratios contained appreciable amounts of polystyryl blocks. The composition of the insoluble fractions of the copolymers was obtained from PGC data and was in good agreement with the composition calculated from the silicon content of the copolymers.© 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91:3774–3784, 2004
Crosslinking structures of gelatin hydrogels crosslinked with genipin or a water‐soluble carbodiimide
Authors: Liang Huang‐Chien , Chang Wen‐Hisung , Liang Hsiang‐Fa , Lee Meng‐Horng , Sung Hsing‐Wen 
Published: January 2004

AbstractIt was suggested in our previous studies that carbodiimide‐ and genipin‐crosslinked gelatin hydrogels could be used as bioadhesives to overcome the cytotoxicity problem associated with formaldehyde‐crosslinked gelatin hydrogels. In this study, we investigated the crosslinking structures of carbodiimide‐ and genipin‐crosslinked gelatin hydrogels. We found that crosslinking gelatin hydrogels with carbodiimide or genipin could produce distinct crosslinking structures because of the differences in their crosslinking types. Carbodiimide could form intramolecular crosslinks within a gelatin molecule or short‐range intermolecular crosslinks between two adjacent gelatin molecules. On the basis of gel permeation chromatography, we found that the polymerization of genipin molecules could occur under the conditions used in crosslinking gelatin hydrogels via a possible aldol condensation. Therefore, besides intramolecular and short‐range intermolecular crosslinks, additional long‐range intermolecular crosslinks could be introduced into genipin‐crosslinked gelatin hydrogels. Crosslinking a gelatin hydrogel with carbodiimide was more rapid than crosslinking with genipin. Therefore, the gelation time for the carbodiimide‐crosslinked gelatin hydrogels was significantly shorter than that of the genipin‐crosslinked gelatin hydrogels. However, the cohesive (interconnected) structure of the carbodiimide‐crosslinked gelatin hydrogels was readily broken because, unlike the genipin‐crosslinked gelatin hydrogels, there were simply intramolecular and short‐range intermolecular crosslinks present in the carbodiimide‐crosslinked hydrogel. In the cytotoxicity study, the carbodiimide‐crosslinked gelatin hydrogels were dissolved into small fragments in the cultural medium within 10 min. In contrast, the genipin‐crosslinked gelatin hydrogels remained intact in the medium throughout the entire course of the study. Again, this may be attributed to the differences in their crosslinking structures. The genipin‐crosslinked gelatin hydrogels were less cytotoxic than the carbodiimide‐crosslinked gelatin hydrogels. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 4017–4026, 2004
Effects of the viscosity ratio on polyolefin ternary blends
Authors: Ha M. H. , Kim B. K. 
Published: January 2004

AbstractPolyolefin binary and ternary blends were prepared from polypropylene (PP), an ethylene–α‐olefin copolymer (mPE), and high‐density polyethylene (HDPE) on the basis of the viscosity ratio of the dispersed phase to the continuous phase. In PP/mPE/HDPE blends, fibrils were observed when the dispersed‐phase (mPE/HDPE) viscosity was less than that of PP, or when the viscosity of mPE was less than that of PP, although the viscosity of mPE/HDPE was greater than that of PP. The notched impact strength and mechanical properties such as the yield strength, flexural modulus, and hardness of PP/mPE binary blends further increased with the addition of HDPE according to the type of HDPE. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 4027–4036, 2004
Gelatin microspheres crosslinked with γ‐ray: Preparation, sorption of proteins, and biodegradability
Authors: Terao Ken , Karino Tomotake , Nagasawa Naotsugu , Yoshii Fumio , Kubo Miyoko , Dobashi Toshiaki 
Published: January 2004

AbstractA new type of gelatin microspheres was manufactured with the crosslinking method by using γ‐ray irradiation. Microspheres thus obtained were characterized by microscopic observation and enzymatic degradability. The mean diameter of the microspheres was in the range from 2.4 to 3.6 μm and the size distribution was quite small. The size decreased with increasing the shear rate of the emulsifier used in the preparation and was not affected by the radiation dose. The enzymatic degradability decreased with increasing the radiation dose and decreasing the gelatin concentration of the microsphere. In other words, the rate of the enzymatic decomposition of microspheres can be controlled by these two parameters. These trends were consistent with our previous results for the gel sheet made of gelatin. Their sorption of proteins was also investigated with the use of three types of proteins labeled by fluorescent pigment. From the fluorescence micrographs, it was observed that the gelatin microspheres adsorbed only proteins having the opposite charge. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3083–3087, 2004
PE/PE‐g‐MAH/Org‐MMT nanocomposites. II. Nonisothermal crystallization kinetics
Authors: Liang Guodong , Xu Junting , Xu Weibing 
Published: January 2004

AbstractThe nonisothermal crystallization kinetics of high‐density polyethylene (HDPE) and polyethylene (PE)/PE‐grafted maleic anhydride (PE‐g‐MAH)/organic‐montmorillonite (Org‐MMT) nanocomposite were investigated by differential scanning calorimetry (DSC) at various cooling rates. Avrami analysis modified by Jeziorny, Ozawa analysis, and a method developed by Liu well described the nonisothermal crystallization process of these samples. The difference in the exponent n, m, and a between HDPE and the nanocomposite indicated that nucleation mechanism and dimension of spherulite growth of the nanocomposite were different from that of HDPE to some extent. The values of half‐time (t1/2), K(T), and F(T) showed that the crystallization rate increased with the increase of cooling rates for HDPE and composite, but the crystallization rate of composite was faster than that of HDPE at a given cooling rate. Moreover, the method proposed by Kissinger was used to evaluate the activation energy of the mentioned samples. It was 223.7 kJ/mol for composite, which was much smaller than that for HDPE (304.6 kJ/mol). Overall, the results indicated that the addition of Org‐MMT and PE‐g‐MAH could accelerate the overall nonisothermal crystallization process of PE. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3054–3059, 2004
Preparation of polysulfone‐coated chitosan beads by emulsion phase‐inversion method
Authors: Chen F. , Luo G. S. , Wang Y. J. 
Published: January 2004

AbstractA new coating method of emulsion phase‐inversion method was suggested, and crosslinked chitosan beads coated with a thin polysulfone (PSF) layer were prepared with the new coating method. The emulsion was composed of PSF, dimethylformamide (DMF), paraffin, and Span 80 as the emulsifier. The effects of the swelling ratio (water content), PSF concentration, phase ratio between PSF in DMF solution and the paraffin phase, as well as coating time on the microstructures and thickness of the coating layer were investigated. The microstructures of the coating layer were determined by SEM microphotographs. Experimental results show that the thickness and the microstructures of the coating layer can be easily controlled with the new coating method. By changing the swelling ratio, PSF concentration, phase ratio in the emulsion, and the coating time, the desired coating layer can be achieved. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3542–3548, 2004
Effect of steric hindrance on hydrogen‐bonding interaction between polyesters and natural polyphenol catechin
Authors: Zhu Bo , Li Jianchun , He Yong , Yamane Hideki , Kimura Yoshiharu , Nishida Haruo , Inoue Yoshio 
Published: January 2004

AbstractThe phase behaviors for the blends of poly(3‐hydroxypropionate) (PHP), poly(L‐lactide) (PLLA), poly(D‐lactide) (PDLA), and poly(D,L‐lactide) (PDLLA) with catechin were investigated by differential scanning calorimetry. In PLLA/catechin, PDLA/catechin, and PDLLA/catechin blends, two glass transitions were detected when the catechin content was ≥40 wt %, whereas in PHP/catechin blends only one glass transition was observed over the whole range of blend compositions. The former and the latter results should reflect the inhomogeneous and the homogeneous nature of the blends, respectively, in the amorphous phase. These different phase behaviors should arise from the differences in the chemical structures between PHP and PLLA/PDLA/PDLLA, which dominates the strength and the number of intermolecular hydrogen‐bonding interactions between the ester carbonyl groups of polyesters and the phenol groups of catechin. As detected by FTIR spectroscopy, in comparison with PHP, the steric hindrance of side‐chain methyl groups of PLLA, PDLA, and PDLLA might restrain the formation of hydrogen bonds between their ester carbonyl groups and the phenol hydroxyl groups of catechin, even weakening the strength of such hydrogen bonds. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3565–3573, 2004
Vernonia oil–based acrylate and methacrylate polymers and interpenetrating polymer networks with epoxy resins
Authors: Kolot Victoria , Grinberg Sarina 
Published: January 2004

AbstractAcrylate and methacrylate monomers were obtained by reacting vernonia oil, a naturally epoxidized oil, with acrylic or methacrylic acid. The highest conversion (85–98%) of epoxy groups was obtained when the reaction was performed with an excess of the carboxylic acid at 100–120°C. The acrylate and methacrylate monomers of vernonia oil were characterized by IR and NMR spectroscopy. These monomers were then cured by sunlight in the presence of benzophenone to produce transparent films. In addition, interpenetrating polymer neworks (IPNs) were prepared in a two‐step technique from the sunlight‐cured methacrylate of vernonia oil, as the elastomeric component, in combination with a cured epoxy resin (a bisphenol A–type resin). Dynamic mechanical analysis showed good compatibility between the networks of the two cured polymers. An IPN with a 1 : 1 composition of the two polymer components exhibited the properties of a reinforced elastomer. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3835–3843, 2004
Study of the thermoformability of ethylene‐vinyl alcohol copolymer based barrier blends of interest in food packaging applications
Authors: Giménez E. , Lagarón J. M. , Cabedo L. , Gavara R. , Saura J. J. 
Published: January 2004

AbstractThe thermoforming capacity of a number of blends of an ethylene‐vinyl alcohol copolymer (EVOH‐32, with 32 mol % ethylene) with amorphous polyamide (aPA) and/or Nylon‐containing ionomer with interest in multilayer food packaging structures have been studied. These blends were vacuum‐thermoformed between 100 and 150°C onto male molds of different shapes and areal draw ratios. It was found that EVOH/aPA extruded blends did not improve the inherently poor formability of EVOH alone. In contrast, significant improvements in thermoformability were achieved by blending EVOH with a compatibilized‐ionomer. Optimum forming capacity was achieved in a ternary blend by addition of a compatibilized‐ionomer to EVOH/aPA blends in the range of 140–150°C. Analysis of wall thickness data obtained in the thermoformed parts showed that wall thickness was significantly affected by the ionomer and amorphous polyamide content in the blend. The ternary blend showed a lower thickness reduction in the critical areas, as well as a higher uniformity in the part. A finite element analysis was used to evaluate the wall thickness distribution and the modeling results were compared with the thermoforming experiments. The simulations were performed for the vacuum‐forming process employing a nonlinear elastic material model. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 96: 3851–3855, 2004
Effect of swelling on the cholesteric structure of ethyl‐cyanoethyl cellulose/crosslinked poly(acrylic acid) composite films
Authors: Wang Xiaohua , Wang Linge , Huang Yong 
Published: January 2004

AbstractThe swelling behavior of ethyl‐cyanoethyl cellulose [(E‐CE)C]/crosslinked poly(acrylic acid) [PAA] cholesteric liquid crystalline composite films and the structural variation of the cholesteric phase during the swelling and the drying process were studied. It was found that the wavelength of the selective reflection of the composite films was shifted to the long wavelength direction during swelling. Both the pitch of the cholesteric phase and the distance between neighboring molecular layers were increased, and the helix axis was inclined after swelling. Moreover, the swelling behavior of the composite films in water was reversible, which means that the optical properties and structural characters of the films could be changed back to their original states after the films were dried from the equilibrium swelling state. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3574–3578, 2004
Effect of hybridization and chemical modification on the water‐absorption behavior of banana fiber–reinforced polyester composites
Authors: Pothan Laly A. , Thomas Sabu 
Published: January 2004

AbstractThe water sorption characteristics of banana fiber–reinforced polyester composites were studied by immersion in distilled water at 28, 50, 70, and 90°C. The effect of hybridization with glass fiber and the chemical modification of the fiber on the water absorption properties of the prepared composites were also evaluated. In the case of hybrid composites, water uptake decreased with increase of glass fiber content. In the case of chemically modified fiber composites, water uptake was found to be dependent on the chemical treatment done on the fiber surface. Weight change profiles of the composites at higher temperature indicated that the diffusion is close to Fickian. The water absorption showed a multistage mechanism in all cases at lower temperatures. Chemical modification was found to affect the water uptake of the composite. Among the treated composites the lowest water uptake was observed for composites treated with silane A1100. Finally, parameters like diffusion, sorption, and permeability coefficients were determined. It was observed that equilibrium water uptake is dependent on the nature of the composite and temperature. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3856–3865, 2004
Evaluation of the thermal and mechanical properties of poly(ε‐caprolactone), low‐density polyethylene, and their blends
Authors: Rosa D. S. , Neto I. Chiovatto , Calil M. R. , Pedroso A. G. , Fonseca C. P. , Neves S. 
Published: January 2004

AbstractThe thermal and mechanical properties of low‐density polyethylene (LDPE), poly(ε‐caprolactone) (PCL), and their blends were evaluated. Differential scanning calorimetry showed that increasing the PCL content of the blend did not change the LDPE melting temperature, but reduced the crystallinity by up to 16.8%. This behavior was related to interactions between the PCL chains and the crystalline phase of LDPE. Tensile strength and elongation at break values for the blends were lower than those for the pure polymers, which suggested an incompatibility between the polymers. The values for Young's modulus under tensile increased when PCL was added to LDPE. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91:3909–3914, 2004
Preferential mineralization of CaCO3 layers on polymer surfaces from CaCl2 and water‐soluble carbonate salt solutions supersaturated by poly(acrylic acid)
Authors: Iwatsubo Takashi , Sumaru Kimio , Kanamori Toshiyuki , Yamaguchi Tomohiko , Sinbo Toshio 
Published: January 2004

AbstractCaCO3 was mineralized from solutions supersaturated only by poly(acrylic acid) (PAA), without bubbling any CO2 gas in the solution. For example, a layer of CaCO3 was built up on the surface of a chitosan membrane from a supersaturated aqueous solution containing CaCl2, Na2CO3, and PAA. In this newly developed method, the PAA alone suppresses the precipitation of CaCO3 from the bulk solution, and therefore, increases the supersaturated concentration. This concentration is estimated to be the same order as that attained in the method in which both CO2 gas and PAA were used. At the same time, PAA supplies nucleation fields by forming a polymer complex with chitosan. The crystal system obtained was different from those obtained when using CO2 gas. Self‐organization of aragonite crystallites led to the formation of uniform, concentric, or branching patterns in the surface‐domain structure. These patterns had morphologies similar to those discovered by other researchers, typically in the crystallization of ascorbic acid. Thicker layers of CaCO3 could be formed on chitosan membranes, the surfaces of which had been converted to a polyelectrolyte complex (PEC) by exposure to PAA solution before the onset of mineralization. Under certain conditions, the CaCO3 layer had a small spherical curvature, similar to a half‐lens, and generated Newton's ring pattern from the interference fringes of visible light. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91:3627–3634, 2004
Effect of crosslinking concentration on the micelle formation inside the polymer gel network and mechanical properties of sensitive hydrogel polymer in contact with surfactant solutions
Authors: Mounir A. , Darwish N. , Shehata A. 
Published: January 2004

AbstractThe variation of the swelling and mechanical properties of crosslinked nonionic poly (N‐isopropylacrylamide) (NIPA) polymer gel immersed in tetradecyl dimethylaminoxide (C14DMAO) surfactant solutions at 0.1M NaCl, synthesized at different crosslinker concentrations was investigated. Also the aggregation behavior of C14DMAO surfactants inside and outside the polymer hydrogels has been studied through solubilization of Sudan III dye. The solubilization experiments indicated that, at the degree of ionization α = 0.5 and 1, the surfactant concentration inside the gel is lower than that outside the gel at low crosslinker concentration. In the case of the nonionic C14DMAO at α = 0, on the other hand, the surfactant concentration inside the gel and outside the gel was almost identical, irrespective of the crosslinker concentration. The elastic modulus, G, of the network polymer gel in contact with the C14DMAO solutions of 5 and 10 mM concentration was larger than that of the water solution irrespective of the degree of ionization (α = 0 and 0.5). This difference in the elastic modulus, G, of network polymer gel may be attributed to the change of the rigidity of the polymer network. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3921–3926, 2004
Hydroxymethylation and polymerization of plant oil triglycerides
Authors: Eren Tarik , Küsefoğlu Selim H. 
Published: January 2004

AbstractThe ene reaction between plant oil triglycerides (such as soybean and sunflower oils) and paraformaldehyde was used to introduce a homoallylic hydroxyl functionality on the triglyceride. Paraformaldehyde and triglyceride were reacted in the presence of a Lewis acid catalyst, ethylaluminum dichloride, and hydroxymethyl derivatives were obtained at yields of 42 and 55% for sunflower oil and soybean oil, respectively. In the next step, hydroxymethyl products were reacted with maleic anhydride at 100°C to produce the maleate half esters. The average number of maleate groups per triglycerides was found to be 1.7 for soybean oil and 1.3 for sunflower oil. In the final step, the free‐radical–initiated copolymerization of the maleinized triglycerides with styrene produced rigid polymers. Characterization of new monomers and polymers was done by 1H‐NMR, 13C‐NMR, and infrared and mass spectrometries. The swelling behavior of the crosslinked network polymers was determined in different solvents. The glass‐transition temperature of the cured resin was also determined by differential scanning calorimetry to be 40°C for soybean‐based polymer and 30°C for sunflower‐based polymer. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 4037–4046, 2004