bluuebunny/crossref_metadata_2025_split huggingface dataset:
Palladium‐catalyzed selective alkoxycarbonylation of N‐vinylphthalimide
Authors: Zhu Bing Chun , Jiang Xuan Zhen 
Published: February 2006

AbstractThe palladium‐catalyzed selective alkoxycarbonylation of enamide was studied using N‐vinylphthalimide as the model substrate. Both palladium (0) and palladium (II) compounds can be used as the catalyst precursors. It was found that the efficiency and the regioselectivity of the reaction depended remarkably on phosphine ligands and other reaction parameters such as solvent, substrate concentration, temperature and promoters. Good yields and high regioselectivities of either the branched or linear products were obtained under optimum reaction conditions. The primary optical yield (12.3%) of N‐Phthaloyl‐L‐alanine methyl ester (2) was obtained using (S)‐(+)‐BNPPA as the chiral ligand. A possible reaction mechanism for the alkoxycarbonylation of N‐vinylphthalimide was also proposed. Copyright © 2006 John Wiley & Sons, Ltd.
Identification of nucleation loci in emulsion polymerization processes. I. New information from spectroscopy studies
Authors: Shastry Vineet , Garcia‐Rubio L. H. 
Published: February 2006

AbstractParticle nucleation is the forcing function in emulsion polymerization reactions and as such it plays a significant role in the development of most of the properties of the final latex. The locus of nucleation in emulsion polymerization remains a contentious issue. Recent developments in the spectroscopy of emulsions strongly suggest that the locus of particle nucleation is a population of small nano‐droplets of size range between 30–100 nanometers in diameter. These nano‐droplets are generated independently of the rate of initiator decomposition and appear to be functions only of the emulsification conditions. In this paper the simulation studies leading to the identification of the nano‐droplet population are described. The theoretical evidence suggesting that the nano‐droplets are the main loci of particle nucleation is presented and along with the recommendations for the experimental work. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2847–2857, 2006
Effect of structural relaxation at physiological temperature on the mechanical property of poly(L‐lactic acid) studied by microhardness measurements
Authors: Wang Yaming , Mano João F. 
Published: February 2006

AbstractBesides hydrolysis, the physical properties of poly(L‐lactic acid), PLLA, may change, at a shorter time‐scale, at physiological temperature, because of structural relaxation. This process may be relevant as it may contribute for the time‐dependent modifications of the mechanical performance of PLLA‐based implants, or in other properties such as specific volume or permeability. In this work, microhardness was measured at room temperature after ageing poly(L‐lactic acid) samples at 37°C during different periods, ranging from 15 min to 15 days. For the PLLA analyzed, the initial Vickers microhardness was around 140 MPa and an increase higher than 55% was observed in a time span of 15 days. The relaxation of enthalpy at 37°C was also monitored by differential scanning calorimetry, and both results were successfully described by a simple model that considers a nonexponential evolution of the quantities sensitive to physical ageing. The time‐scales of the structural relaxation probed by microhardness or by enthalpy were different, and the results suggested that the evolution of the mechanical property was slower than the later. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2628–2633, 2006
Role of mixing parameters in the preparation of poly(ethylene vinyl acetate) nanocomposites by melt blending
Authors: Tillekeratne Mangala , Jollands Margaret , Cser Ferenc , Bhattacharya Sati N. 
Published: February 2006

AbstractPolymer/layered‐silicate nanocomposites have gathered momentum as cost‐effective and versatile materials since the middle of the 20th century. Many publications discuss the chemistry of organomodification and properties of nanocomposites, but relatively few deal with the significance of processing conditions. This article takes into account three mixing parameters and discusses the contribution of each toward nanocomposite formation. Organomodified natural sodium‐type bentonite clay was used in this study. The nanocomposites formed were characterized by X‐ray diffraction and mechanical property tests. Response surface regression was used to optimize the tensile modulus. The analysis shows that nanocomposite formation is promoted by a diffusion mechanism and that the interactions of parameters are as important as individual parameters. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2652–2658, 2006
Evaluation of fiber wettability based on an immerging force measurement
Authors: Xiao Hong , Yu Weidong , Shi Meiwu 
Published: February 2006

AbstractThis article provides a new approach to estimate the wettability of fibers based on the force analysis in immerging procedure. A fiber in horizontal is forced into and withdrawn from the liquid at a certain speed, and the force changes are detected simultaneously. The experimental results show that the force impulse can be found at fiber contacting with liquid and immersed into liquid, and its value depends on the wettability of the fiber. According to the force impulses of different fibers, the immerging behavior of the fibers can be obtained and categorized into four characteristics. Meanwhile, the wettability of the fibers can be evaluated with the wettability factor, w, derived from the fiber immerging curve, where w is the ratio of the force increment on fiber initially contacting with the liquid to the force increment on liquid surface closing with fiber immerging into the liquid, and with the contact angle, θ, calculated from the wettability factor (θ = π/(w+1)) supposed that the fiber is a circular cross section. The pulling‐out test for a fiber has also been conducted and the results are discussed briefly in this article. The force measurement indicates that the method can be used for various fibers with short length, or lower density than that of the liquid, or poor wettability. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2659–2666, 2006
Preparation by melt mixing and characterization of isotactic polypropylene/SiO2 nanocomposites containing untreated and surface‐treated nanoparticles
Authors: Bikiaris Dimitris N. , Papageorgiou George Z. , Pavlidou Eleni , Vouroutzis Nikolaos , Palatzoglou Paraskevas , Karayannidis George P. 
Published: February 2006

AbstractIn the present study two series of isotactic polypropylene (iPP)/SiO2 nanocomposites containing 1, 2.5, 5, 7.5, and 10 wt % SiO2 nanoparticles were prepared by melt‐mixing on a twin‐screw corotating extruder. In the first series untreated fumed silica nanoparticles were used, whereas in the second nanoparticles were surface‐treated with dimethyldichlorosilane. In both cases, the average size of the primary nanoparticles was 12 nm. Tensile and impact strength were found to increase and to be affected mainly by the type and content of silica nanoparticles. A maximum was observed, corresponding to samples containing 2.5 wt % SiO2. These findings are discussed in light of the SEM and TEM observations. By increasing the amount of nanoparticles, large aggregates of fumed silica could be formed, which may explain the reduction of mechanical properties with higher concentrations of SiO2. However, it was found that surface‐treated nanoparticles produced larger aggregates than did those derived from untreated nanoparticles, despite the increased adhesion of the iPP matrix, as was postulated from yield strength. This behavior negatively affected mechanical properties. In addition, an effort was made to determine if toughening theories, mainly the critical interparticle distance for rubber toughening or composites, also might be applicable in nanocomposites. From DSC measurements it was demonstrated that silica nanoparticles acted as effective nucleating agents, increasing the crystallization rate and the degree of crystallinity of iPP. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2684–2696, 2006
Improving easy care nonformaldehyde finishing performance using polycarboxylic acids via precationization of cotton fabric
Authors: Hebeish A. , Hashem M. , Abdel‐Rahman A. , El‐Hilw Z. H. 
Published: February 2006

AbstractCotton fabric were first subjected to quaternization (cationization) reaction using 3‐chloro‐2‐hydroxypropyl trimethyl ammonium chloride commercially known as Quat®‐188. Cationization was carried out under different conditions for optimization of the preparation of cationized cotton with different degrees of cationization, using the pad‐batch method. Also, established was the optimal condition for cationization that involves Quat‐188/NaOH molar ratio 1/2 at 70°C for 4 h. Besides, a thorough investigation of factors affecting reaction of these cationized cotton with citric acid (CA) or 1,2,3,4‐butanetetracarboxylic acid (BTCA) was carried out with a view of improving the ease of care characteristics of nonformaldehyde finishing. The dependence of fabric performance as measured by strength properties, dry wrinkle recovery angles, whiteness index, and dyeability with reactive dyes was also evaluated. It was postulated that reaction of cationized cotton with either CA or BTCA involves estercrosslinking as well as ionic crosslinking. This, indeed, was largely positively reflected on the fabric performance especially when the properties of both uncationized cotton were compared with those of the cationized cotton. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2697–2704, 2006
Synthesis and adsorption properties of metal ions of novel azacrown ether crosslinked chitosan
Authors: Zhang Xueyong , Ding Shimin , Wang Yuting , Feng Xianghua , Peng Qi , Ma Shulan 
Published: February 2006

AbstractAzacrown ether chitosan (CTSC) was synthesized by the reaction of chitosan with N‐allyl benzo 15‐crown‐5 crown ether. Azacrown ether crosslinked chitosan (CCTSC) was prepared by the crosslinked reaction of CTSC and epichlorodydrin. Their structures were confirmed by infrared spectral analysis and X‐ray diffraction analysis. The adsorption properties of CTSC and CCTSC for metal ions were also investigated. The experimental results showed that the two chitosan derivatives not only had a good capacity to adsorb Pd2+ and Ag+ but also was highly selective for Pd2+ and Ag+ in the coexistence system containing other metal ions. At 20°C ± 1°C and pH = 4, the adsorption capacity of CTSC and CCTSC for Pd2+ was 186.1 and 173.1 mg/g, respectively; and for Ag+ was 90.2 and 56.5 mg/g, respectively. The selectivity coefficients were K = 6.99, K = ∞, K = 35.38, K = ∞ for CTSC and K = 10.66, K = ∞, K = 85.45, K = ∞ for CCTSC. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2705–2709, 2006
Fabrication of arrays of silver nanoparticle aggregates by microcontact printing and block copolymer nanoreactors
Authors: Cong Yang , Fu Jun , Zhang Zexin , Cheng Ziyong , Xing Rubo , Li Jian , Han Yanchun 
Published: February 2006

AbstractA combination of microcontact printing and block copolymer nanoreactors succeeded in fabricating arrays of silver nanoparticle aggregates. A complex solution of polystyrene‐block‐poly(4‐vinylpyridine) micelles and silver salt was used as an ink to form thin films or droplets on polydimethylsiloxane stamp protrusions. After these complex aggregates were printed onto silicon substrates under controlled conditions, highly ordered arrays of disklike, dishlike, and dotlike complex aggregates were obtained. A subsequent oxygen reactive ion etching treatment yielded arrays of silver nanoparticle aggregates. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2737–2743, 2006
Factorial experimental design for graft copolymerization of styrene and methyl methacrylate onto styrene–butadiene rubber
Authors: Arayapranee W. , Prasassarakich P. , Rempel G. L. 
Published: February 2006

AbstractThe graft copolymerization of styrene (ST) and methyl methacrylate (MMA) onto styrene–butadiene rubber (SBR) latex prepared by seeded emulsion polymerization has been studied under various reaction conditions using cumene hydroperoxide redox initiator. The mechanism of graft copolymerization has been investigated. The synthesized graft copolymers were purified and then characterized by proton nuclear magnetic resonance (1H NMR) analysis. A 2 2 fractional factorial experimental design was applied to study the effects of the process variables such as the amount of initiator and emulsifier, the presence or absence of chain‐transfer agent, ST to MMA ratio, monomer to rubber ratio, and reaction temperature on the grafting efficiency. The analysis of the results from the design showed the sequence of the main effect on the observed response of the grafting of ST and MMA onto SBR and that the amount of chain‐transfer agent had a significant effect. Transmission electron microscopy was used to study the morphology of the graft copolymers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2867–2874, 2006
Poly(acrylamide‐co‐maleic acid) hydrogels for removal of Cr(VI) from aqueous solutions, Part 1: Synthesis and swelling characterization
Authors: Bajpai S. K. , Johnson Susamma 
Published: February 2006

AbstractThe swelling behavior of poly (acrylamide‐co‐maleic acid) hydrogels has been investigated in distilled water at 30°C. The gels were characterized with respect to structural parameters, Fourier transform infrared, and thermogravimetric analysis. The gels showed fair pH‐dependent swelling and exhibited double “s”‐shaped curve between equilibrium water uptake and pH of the swelling media. The two pKa values, as determined from the curve, were found to be 2.46 and 6.58. The activation energy of the water uptake process for plain and acid containing gels was found to be 7.93 and 3.26 kJ mol−1 respectively. Similarly, the enthalpy of mixing between dry polymer and solvent showed positive values, thus indicting endothermic nature of the process, and the values increased from 10.06 to 16.29 kJ mol−1 with increase in acid content from 2.1 × 10−1 to 4.7 × 10−1 mM respectively. There was an optimum initiator concentration 24.0 × 10−2 mM and reaction temperature 60°C at which gels synthesized showed maximum absorbency. The dilution of the reaction mixture resulted in the formation of hydrogels with enhanced absorbency. Finally, the gels with varying content of monomer acid in the feed mixture showed different swelling behavior when studied in the medium of pH 1.0 and 7.0. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2759–2769, 2006
Physicomechanical, optical, barrier, and wide angle X‐ray scattering studies of filled low density polyethylene films
Authors: Siddaramaiah  , Guruprasad K. H. , Nagaralli R. T. , Somashekarappa H. , Guru Row T. N. , Somashekar R. 
Published: February 2006

AbstractSeries of low density polyethylene (LDPE) films filled with different fillers such as silica, mica, soya protein isolate, potassium permanganate, and alumina were processed using a single screw extruder. The filled LDPE films were characterized for physicomechanical properties like tensile strength, percentage elongation at break, and tear strength, optical properties like percent transmission and haze. The barrier properties such as water vapor transmission rate and oxygen transmission rate of the filled LDPE films have also been reported. Microcrystalline parameters such as crystal size (〈N〉) and lattice distortion (g) of the filled LDPE films obtained using wide angle X‐Ray scattering method have been reported. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2781–2789, 2006
Synthesis and elastomer behavior of a novel polymer electrolyte of acrylic ester–salt copolymer
Authors: Tang Jianguo , Wang Dongqing , Wang Yao , Liu Haiyan , Wang Xiaomei 
Published: February 2006

AbstractThis paper studied the synthesis of a novel elastomeric copolymer electrolyte in an aqueous phase. The monomer, sodium allyl sulfonate (SAS), was dissolved in continuous aqueous phase and the second monomer, methyl acrylate (MA), was supplied from MA micelles as dispersed phase. The copolymerization of the two monomers took place in continuous aqueous phase. Confirmed by FTIR and 1H‐NMR, a binary copolymer electrolyte of MA and SAS, poly(MA‐co‐SAS), was obtained. The glass transition temperature of the copolymer was indicated as 20.4°C by DSC thermogram, thus, it behaves an elastomer in normal ambient temperature. The mechanical properties of the composite films consisting of both poly(MA‐co‐SAS) and Cu2+ ions or reduced copper were affected by the content of ions and reduced copper. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2796–2802, 2006
The effect of the architecture and concentration of styrene–butadiene compatibilizers on the morphology of polystyrene/low‐density polyethylene blends
Authors: Fortelný Ivan , Šlouf Miroslav , Sikora Antonín , Hlavatá Drahomíra , Hašová Věra , Mikešová Jana , Jacob Ceni 
Published: February 2006

AbstractThe effect of styrene–butadiene block copolymers (SB) with varying number of blocks and length of styrene blocks on the morphology, rheology, and impact strength of 4/1 polystyrene/low‐density polyethylene (PS/LDPE) blends was studied. The scanning and transmission electron microscopy and X‐ray scattering were used for determination of the size of LDPE particles and the localization and structure of SB copolymers in blends. It is shown that the dependence of the LDPE particle size on the amount of added SB and localization of SB copolymers in blends is predominantly controlled by the length of their styrene blocks. It follows from thermodynamic considerations that the reason is the difference in composition asymmetry between SB with short and long styrene blocks. Coalescence of particles of SB having short styrene blocks at the surface of LDPE droplets and movement of SB with long styrene blocks to the PS–LDPE interface were observed during annealing of PS/LDPE/SB blends. Pronounced migration of SB copolymer during annealing shows that their localizations in blends in steady state on long steady mixing and at thermodynamic equilibrium are different. The values of tensile impact strength of PS/LDPE/SB blends correlate well with the size of LDPE particles and the amount of SB at the interface. Viscosity of PS/LDPE/SB depends on molecular structure of SB copolymers by a manner different from that of tensile impact strength. The results of this study and literature data lead to the conclusion that the compatibilization efficiency of SB copolymers for a certain polystyrene‐polyolefin pair is a function of not only molecular parameters of SB but also of the polystyrene/polyolefin ratio, the amount of SB in a blend, and mixing and processing conditions. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2803–2816, 2006
Influence of feedback in the structure of carbon plastics on their properties
Authors: Kozlov G. V. , Burya A. I. , Zaikov G. E. 
Published: February 2006

AbstractThe results in the present article allow to find a structural sense of feedback effect in carbon plastics based on phenylone and demonstrated its influence on the strength of these materials. The decrease of feedback parameter can be a result of a substantial increase of carbon plastics macroscopic strength. The control of the value of this parameter is possible by the change of fibers orientation factor, which is the controlling parameter for interfacial regions. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2817–2820, 2006
Anisotropy of a fiber structure and the frictional wear of composites on the basis of polyarylate
Authors: Kozlov G. V. , Burya A. I. , Zaikov G. E. 
Published: February 2006

AbstractAn influence of the anisotropy of surface structure of short fibers on an interfacial layer structure in polymer composites is studied. In its turn, mentioned changes of structure cause an essential variation of frictional wear for these materials. In this aspect, the existence of a hydrogen bonds polymer‐filler plays an important role. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2821–2823, 2006
Kinetic and molecular weight control for methyl methacrylate semi‐batch polymerization. I. Modelling
Authors: Wu Jian‐Yi , Shan Guo‐Rong 
Published: February 2006

AbstractThere are gel, glass, and cage effects in the methyl methacrylate (MMA) bulk polymerization. These effects will cause the propagation and termination rate constants and initiator efficiency change during the polymerization process, and make the kinetics and molecular weight more complex. A violent increase of conversion will bring a large amount of reaction heat evolved in a short time, and will promote temperature increase if the heat cannot be removed in time. Molecular weight of polymer will raise ten times at the same time. So, the temperature of polymerization system, kinetics of polymerization, and molecular weight and its distribution of polymer cannot be controlled. To control and unify them, the semibatch polymerization method is preferably selected. Furthermore, the kinetic and molecular weight models for MMA semibatch polymerization with the participation of chain transfer agent and new materials addition flow rate are presented. Using the presented models, the effects of temperature, initiator concentration and type, monomer or solvent concentration, and chain transfer agent concentration and type on the kinetics, and molecular weight and its distribution are simulated in this article. Experimental data of kinetics and molecular weight obtained from the published literature are compared with the simulation results to examine the presented models. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2838–2846, 2006
Fine structural dependence of ultraviolet reflections in the King Penguin beak horn
Authors: Dresp Birgitta , Langley Keith 
Published: February 2006

AbstractThe visual perception of many birds extends into the near‐ultraviolet (UV) spectrum and ultraviolet is used by some to communicate. The beak horn of the King Penguin (Aptenodytes patagonicus) intensely reflects in the ultraviolet and this appears to be implicated in partner choice. In a preliminary study, we recently demonstrated that this ultraviolet reflectance has a structural basis, resulting from crystal‐like photonic structures, capable of reflecting in the near‐UV. The present study attempted to define the origin of the photonic elements that produce the UV reflectance and to better understand how the UV signal is optimized by their fine structure. Using light and electron microscopic analysis combined with new spectrophotometric data, we describe here in detail the fine structure of the entire King Penguin beak horn in addition to that of its photonic crystals. The data obtained reveal a one‐dimensional structural periodicity within this tissue and demonstrate a direct relationship between its fine structure and its function. In addition, they suggest how the photonic structures are produced and how they are stabilized. The measured lattice dimensions of the photonic crystals, together with morphological data on its composition, permit predictions of the wavelength of reflected light. These correlate well with experimentally observed values. The way the UV signal is optimized by the fine structure of the beak tissue is discussed with regard to its putative biological role. © 2006 Wiley‐Liss, Inc.