bluuebunny/crossref_metadata_2025_split huggingface dataset:
Acute stroke therapy with tissue plasminogen activator (tPA) since it was approved by the U.S. Food and Drug Administration (FDA)
Authors: Zivin Justin A. 
Published: August 2009

AbstractTissue plasminogen activator (tPA) for acute ischemic stroke was approved by the U.S. Food and Drug Administration (FDA) in 1996. Since then it has been severely underutilized. At the time when most practitioners were first being exposed to the literature concerning tPA, there were many concerns about safety and the restrictions on use were quite onerous. Since then a good deal of further work has been done to loosen the restrictions and allay concerns about the risks. The true risk to benefit ratio is far better than is generally realized. Now it is mostly economic problems related to the costs of constantly supplying emergency care that is limiting access. Furthermore, in the current litigious environment, failure to treat is likely to be a more hazardous course of action than legal exposure due to poor outcomes. It must be emphasized that the drug is quite safe and highly effective, and current utilization rates are unacceptably low. Ann Neurol 2009;66:6–10
Quick assessment of the thermal decomposition behavior of lignocellulosic biomass by near infrared spectroscopy and its statistical analysis
Authors: Lee Seung‐Hwan , Cho Hyun‐Woo , Labbé Nicole , Jeong Myong K. 
Published: August 2009

AbstractThe application of near infrared (NIR) spectroscopy for the prediction of the thermal decomposition behavior of lignocellulosic biomass (three types of woody biomass and three types of herbaceous biomass) was successfully performed along with statistical analysis. The thermal degradation behaviors of the woody and herbaceous biomass were different because of their different chemical compositions. Herbaceous biomass was degraded at lower temperature than woody biomass. The weight‐loss profiles as a function of temperature were obtained by thermogravimetric analysis (TGA) at a heating rate of 25°C/min under nitrogen gas. The weight‐loss percentage at 10 temperatures in the range 150–600°C was predicted by a wavelet partial least squares (PLS) model, which showed significantly better predictive performance than the ordinary PLS model. The results show that the data predicted by the wavelet PLS model was well fitted to the original data by TGA, in which the root‐mean‐square error in prediction values less than 5.5 suggested that NIR spectroscopy was applicable for rapid analysis to characterize the thermal decomposition behavior of lignocellulosic biomass for energy production. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Experimental characterization and modeling stiffness of polymer/clay nanocomposites within a hierarchical multiscale framework
Authors: Mesbah A. , Zaïri F. , Boutaleb S. , Gloaguen J. M. , Naït‐Abdelaziz M. , Xie S. , Boukharouba T. , Lefebvre J. M. 
Published: August 2009

AbstractTo provide a better understanding of the relationship between nanostructure and overall material stiffness in the case of polymer/clay nanocomposites, both analytical and finite element modeling were considered. A micromechanical analytical approach based on a multiscale framework is presented in which special attention is devoted to the constrained region around reinforcements. The thickness of the constrained region is seen as a characteristic length scale and the effect of particle size is explicitly introduced in the model. Moreover, the constrained region presents graded properties. The hierarchical morphology of intercalated silicate stacks is also explicitly introduced in the micromechanical model from an equivalent stiffness method in which the silicate stacks are replaced by homogeneous particles with constructed equivalent anisotropic stiffness. The orientational averaging process is used to derive the overall stiffness tensor of nanocomposite materials containing randomly oriented reinforcements. The respective influence of volume fraction, aspect ratio, size and orientation of the reinforcements, matrix properties, number of silicate layers per stack, and interlayer spacing on the overall nanocomposite stiffness is analyzed. The overall stiffness of polymer/clay nanocomposite systems is also evaluated by means of finite element simulations and the results compare favorably with model predictions. From an experimental point of view, relevant morphological and mechanical data were obtained on polyamide‐6 nanocomposites prepared using a modified montmorillonite Cloisite 30B and an unmodified sodium montmorillonite Cloisite Na+. The amount of constrained region around reinforcements was estimated using results issued from dynamic mechanical analyses and differential scanning calorimetry. Comparison to the model clearly underlines the contribution of the constrained region to the stiffness improvement. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Characterization of enzyme‐deproteinized skim rubber
Authors: George K. Mariamma , Alex Rosamma , Joseph Susamma , Thomas K. T. 
Published: August 2009

AbstractSkim natural rubber latex is a protein‐rich byproduct obtained during the centrifugal concentration of natural rubber latex. Skim latex has a very low dry rubber content (4–8%), and the rubber particles are smaller in size. It has a higher proportion of nonrubber solids, which are mostly proteinaceous in nature. It is difficult to coagulate, and it takes more processing time. The proteins in skim latex can be decomposed by proteolytic enzymes. This article discusses the use of stabilized liquid papain from the papaya plant (Carica papaya) for deproteinization followed by creaming for quick and easy coagulation of skim latex. The technological properties and aging characteristics of the deproteinized skim rubber are compared with those of conventionally prepared skim rubber and block rubber. The deproteinized skim rubber showed enhanced quality parameters. Particle size analysis revealed that deproteinization and creaming of the skim latex did not markedly change the particle size. Gel permeation chromatography showed a reduction in the quantity of fatty acids after deproteinization and creaming, which was reflected in the improvement of the aging characteristics in comparison with the control sample. Vulcanizates prepared with the deproteinized skim rubber had higher resilience, lower heat buildup, lower compression set, and good tensile strength and elongation at break in comparison with conventionally prepared skim rubber, and the properties were almost comparable to those of block rubber. The improvement in the mechanical properties and aging characteristics could be attributed to the reduction of the protein content, the partial removal of unsaturated fatty acids, and the removal of metal ions that were pro‐oxidants during the deproteinization and creaming process. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Dielectric properties and solubility of multilayer hyperbranched polyimide/polyhedral oligomeric silsesquioxane nanocomposites
Authors: Somboonsub Bongkoch , Thongyai Supakanok , Praserthdam Piyasan 
Published: August 2009

AbstractMultilayer hyperbranched polyimide/polyhedral oligomeric silsesquioxane (POSS) nanocomposites were synthesized by the reaction of a bromide‐hyperbranched polyether/POSS and a main‐chain polyimide containing hydroxyl‐functional groups. The first layer was formed through the direct reactions of the main‐chain hydroxyl groups with monochloroisobutyl polyhedral oligomeric silsesquioxane (POSS–Cl). The second and third layers were prepared by the repeated reactions of bromine ether branches that incorporated POSS–Cl with 3,5‐dihydroxybenzyl alcohol. Regardless of the fixed amount of POSS, the higher layers yielded lower dielectric constants. Even when the amount of the POSS loading was reduced 4‐fold, the third layer still had the lowest dielectric constants. The lowest dielectric constant of 2.54 was found in the third layer of the hyperbranched polyimide/POSS nanocomposite because of the large free volume and loose polyimide structures. The densities of the hyperbranched polyimide/POSS nanocomposite corresponded to the dielectric constants. The lower the density was, the higher the free volume was and the lower the dielectric constant was. The experimental results indicated that the hyperbranched polyimide/POSS nanocomposite exhibited increased solubility in comparison with pure polyimide. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Preparation of a crosslinked polyelectrolyte membrane for fuel cells with an allyl methacrylate based two‐step reaction
Authors: Kishi Akira , Umeda Minoru 
Published: August 2009

AbstractIn this study, a proton‐exchange membrane for fuel cells was prepared via a two‐step reaction with an allyl methacrylate (AMA) as an asymmetric crosslinking agent. First, a linear‐chain polymer was synthesized, consisting of hydrophilic 2‐acrylamido‐2‐methylpropanesulfonic acid (AMPS), hydrophobic 2,2,2‐trifluoroethyl methacrylate (TFEMA), and AMA. Subsequently, we crosslinked the linear‐chain polymer by reacting the remaining allyl group during dry heating. The proton conductivity of the prepared membrane was 7 × 10−2 S/cm at room temperature. The membrane was characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, and atomic force microscopy. The polymer electrolyte membrane fuel cell (PEMFC) performance was evaluated for a membrane electrode assembly composed of the crosslinked AMPS–TFEMA–AMA/ fluoroalkyl graft polymer (FGP) membrane. As a result of a power‐generation test, a maximum power density of 174 mW/cm2 at a current density of 400 mA/cm2 was observed for a PEMFC single cell. Consequently, it was confirmed that the AMPS–TFEMA–AMA/FGP membrane for PEMFC could easily be prepared via a two‐step reaction at a low cost and that PEMFC exhibited a cell performance and that of cells with the Nafion membrane. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
A relatively simple method for calculating Mark‐Houwink parameters using basic definitions
Authors: Braun Jennifer L. , Kadla John F. 
Published: August 2009

AbstractA method for calculating Mark‐Houwink parameters from intrinsic viscosity, size exclusion, and number‐ or weight‐average molecular weight data using basic definitions was presented. Polydispersity is not an issue and no calibration curve is required as long as all of the aforementioned data are available. Results for polystyrene, cellulose acetate, and polymethylhydrosiloxane are discussed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Synthesis and characterization of novel fluorine‐containing methacrylate copolymers: Reactivity ratios, thermal properties, and antimicrobial activity
Authors: Erol Ibrahim , Sen Ozkan , Dedelioglu Ayse , Cifci Cemal 
Published: August 2009

AbstractThe free‐radical‐initiated copolymerization of 2‐(4‐acetylphenoxy)‐2‐oxoethyl‐2‐methylacrylate (AOEMA) and 2‐(4‐benzoylphenoxy)‐2‐oxoethyl‐2‐methylacrylate (BOEMA) with 2‐[(4‐fluorophenyoxy]‐2‐oxoethyl‐2‐methylacrylate (FPEMA) were carried out in 1,4‐dioxane solution at 65°C using 2,2′‐azobisisobutyronitrile as an initiator with different monomer‐to‐monomer ratios in the feed. The monomers and copolymers were characterized by FTIR and 1H‐ and 13C‐NMR spectral studies. 1H‐NMR analysis was used to determine the molar fractions of AOEMA, BOEMA, and FPEMA in the copolymers. The reactivity ratios of the monomers were determined by the application of Fineman‐Ross and Kelen‐Tudos methods. The analysis of reactivity ratios revealed that BOEMA and AOEMA are less reactive than FPEMA, and copolymers formed are statistically in nature. The molecular weights (Mw and Mn) and polydispersity index of the polymers were determined using gel permeation chromatography. Thermogravimetric analysis of the polymers reveals that the thermal stability of the copolymers increases with an increase in the mole fraction of FPEMA in the copolymers. Glass transition temperatures of the copolymers were found to decrease with an increase in the mole fraction of FPEMA in the copolymers. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Studies on structure property correlation of cross‐linked glycidyl azide polymer
Authors: Manu S. K. , Varghese T. L. , Mathew S. , Ninan K. N. 
Published: August 2009

AbstractGlycidyl azide polymer (GAP) has been evaluated for use as binder for solid propellants. The effects of various parameters like cross‐linking conditions, concentration of crosslinker, and the ratio of isocyanate to hydroxyl functional groups (NCO/OH ratio) on the mechanical properties were studied in detail. It was observed that the type of curing agent and the NCO/OH ratio have a strong influence on the gum‐stock properties. Similar impact was seen for cross‐linker concentration also. The swelling characteristics of the cross‐linked binder prepared with different NCO/OH ratios were evaluated with toluene and tetrahydrofuran (THF). The polarity and the solubility parameter of the solvents were found to influence the swelling of GAP. The NCO/OH ratio and cross‐linker concentration of the polymer were also found to affect the swelling characteristics. The sol fraction determined for the polymer was found to follow a similar pattern. The cross‐link density and average molecular weight between crosslinks (Mc) were determined from the swelling studies and also from the stress–strain relationship. The Mc values were found to be influenced by the NCO/OH ratio. Finally, the Mc values determined from the swelling data were correlated to the gum‐stock properties, and the model parameters were estimated. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Effect of crystallinity on surface morphology and light transmittance of poly(vinylidene fluoride‐co‐hexafluoropropylene) thin film
Authors: Lee Sang Goo , Lee Jong Sung , Ha Jong‐Wook , Park In Jun , Lee Soo‐Bok , Lee Jong Dae 
Published: August 2009

AbstractHomopolymer of vinylidene fluoride and its copolymers containing hexafluoropropylene (HFP) were prepared from free radical solution polymerizations and spin‐coated on the glass slides to fabricate thin film with a thickness of ∼ 1 μm. It was found that the surface morphology of fluorinated thin films was strongly dependent on the crystallinity of polymers. In addition, the surface morphology was the most important factor to determine the optical transmittance of glass coated with the fluoropolymer thin film. As decreasing the crystallinity of the polymer by introducing HFP with a bulky CF3 moiety, the surface of thin film became flattened and the transmittance of visible light was increased by reducing scattering. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
The conduction characteristics of electrical trees in XLPE cable insulation
Authors: Xie Ansheng , Zheng Xiaoquan , Li Shengtao , Chen George 
Published: August 2009

AbstractDepending on the morphology of the material and applied voltage frequency, three kinds of electrical trees can exist in cross‐linked polyethylene (XLPE) cable insulation, which are conducting, non‐conducting, and mixed trees with different growth mechanisms. It is suggested that when the needle is inserted into large spherulites, conducting trees will form in those spherulites; when it is inserted among spherulites, non‐conducting trees will appear along the boundaries of spherulites. Frequency will accelerate the growth of non‐conducting trees but have little influence on the initiation and growth processes of conducting trees. If the initiation process of non‐conducting trees is too difficult, they will grow into mixed trees. Finally, it is concluded that the space charge limited tiny breakdown around the tips of electrical trees is responsible for the propagation process of conducting trees; on the other hand, fast expansion occurs due to local high temperature and pressure along the boundaries, partial discharge in electrical tree paths and charge recombination, etc., which are the main reason for the growth of non‐conducting trees. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Thermomechanical and optical properties of biodegradable poly(L‐lactide)/silica nanocomposites by melt compounding
Authors: Wen Xin , Lin Ying , Han Changyu , Zhang Kunyu , Ran Xianghai , Li Yuesheng , Dong Lisong 
Published: August 2009

AbstractPoly(L‐lactide) (PLA)/silica (SiO2) nanocomposites containing 1, 3, 5, 7, and 10 wt % SiO2 nanoparticles were prepared by melt compounding in a Haake mixer. The phase morphology, thermomechanical properties, and optical transparency were investigated and compared to those of neat PLA. Scanning electron microscopy results show that the SiO2 nanoparticles were uniformly distributed in the PLA matrix for filler contents below 5 wt %, whereas some aggregates were detected with further increasing filler concentration. Differential scanning calorimetry analysis revealed that the addition of SiO2 nanoparticles not only remarkably accelerated the crystallization speed but also largely improved the crystallinity of PLA. An initial increase followed by a decrease with higher filler loadings for the storage modulus and glass‐transition temperature were observed according to dynamic mechanical analysis results. Hydrogen bonding interaction involving CO of PLA with SiOH of SiO2 was evidenced by Fourier transform infrared analysis for the first time. From the mechanical tests, we found that the tensile strength and modulus values of the nanocomposites were greatly enhanced by the incorporation of inorganic SiO2 nanoparticles, and the elongation at break and impact strength were slightly improved. The optical transparency of the nanocomposites was excellent, and it seemed independent of the SiO2 concentration; this was mainly attributed to the closed refractive indices between the PLA matrix and nanofillers. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Preparation and characterization of CMCS/PVA blend membranes and its sorption and pervaporation performance (I)
Authors: Shen Jiang‐Nan , Ruan Hui‐Min , Gao Cong‐Jie 
Published: August 2009

AbstractNovel pervaporation (PV) membranes for ethanol dehydration were prepared by blend poly(vinyl alcohol) (PVA) and carboxymethyl chitosan (CMCS), followed by the crosslinking reaction with glutaraldehyde; the structure and miscibility of the blend membranes were characterized by Fourier transform infrared, X‐ray diffraction, and differential scanning calorimetry; the results indicated that the blends were miscible. The effect of feed concentration, operation temperature, crosslinking agent content, etc. on sorption performance and PV performance of the blend membrane is investigated. The membrane of CMCS/PVA blend ratio of 8 : 2 exhibited a high separation factor of 2959 with a reasonably high water flux value of 0.14 kg m−2h−1 at the azeotropic feed composition (95 wt % of ethanol) at a temperature of 45°C. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Effects of prior aging at 288°C in argon environment on time‐dependent deformation behavior of a thermoset polymer at elevated temperature, Part 2: Modeling with viscoplasticity theory based on overstress
Authors: McClung Amber J. W. , Ruggles‐Wrenn Marina B. 
Published: August 2009

AbstractThe viscoplasticity based on overstress (VBO) is augmented to model the effects of prior isothermal aging in an argon environment on the inelastic deformation behavior of PMR‐15 neat resin, a high‐temperature thermoset polymer. VBO is a unified state variable theory with growth laws for three state variables: the equilibrium stress, the kinematic stress and the isotropic stress. A systematic model characterization procedure based on a limited number of well defined experiments is employed to determine the VBO parameters. Experimental findings presented in Part I reveal the equilibrium stress and the kinematic stress to be affected by prior aging. Based on the experimental results, the isotropic stress is developed as a function of prior aging time. In addition, several VBO model parameters are made dependent on prior aging time. Comparison with experimental data demonstrates that the modified VBO successfully predicts the inelastic deformation behavior of the PMR‐15 polymer subjected to prior isothermal aging for up to 2000 h. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Synthesis and characterization of poly(esteramide‐urethane) from linseed oil as anticorrosive coatings
Authors: Alam Manawwer , Ray Alok R. , Ahmad Sharif 
Published: August 2009

AbstractEthylene diamine polyesteramide (Ed‐PEA) was synthesized from N, N‐bis (2‐hydroxy ethyl) linseed oil fattyamide and ethylene diamine tetra acetic acid through condensation polymerization. It was further treated with toluylene 2,4‐diisocyanate (TDI) in different weight percentage to obtain urethane‐modified polyesteramide (Ed‐UPEA). The structural elucidation of Ed‐PEA and Ed‐UPEA were carried out by FTIR, 1H‐NMR, and 13C‐NMR spectroscopic techniques. Thermal studies of these resins were carried by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The coatings of urethane‐modified polyesteramide were prepared on mild steel strips and their anticorrosive behavior of in acid, alkali, water, and xylene were investigated. Thermal stability performance suggests that the system could be safely used upto 200°C. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Silicone‐based cholesteric liquid crystalline polymers: Effect of crosslinking agent on phase transition behavior
Authors: Jana Rabindranath N. , Cho Jae Whan 
Published: August 2009

AbstractSilicone‐based cholesteric liquid crystalline polymers (ChLCP) were fabricated with variable clearing temperatures as controlled by their chemical compositions. The chemical structures of the mesogenic monomers and ChLCP were confirmed by FTIR and 1H‐NMR spectroscopy. The mesogenic properties and phase behavior were investigated by differential scanning calorimetry, polarizing optical microscopy, and X‐ray diffraction measurements. The experimental results demonstrated that the glass transition temperatures and the clearing points of the liquid crystalline polymers decreased with increasing proportion of mesogenic crosslinking agent up to 12.50 mol % (LCP‐3), and at higher proportion of crosslinking agent, the clearing points disappeared, indicating that the network chains have less chance to orient themselves. Thermogravimetric analysis showed that the LCP‐3 was the most stable up to 230°C. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
A novel intumescent flame‐retardant system for flame‐retarded LLDPE/EVA composites
Authors: Li Bin , Jia He , Guan Limin , Bing Baichun , Dai Jinfeng 
Published: August 2009

AbstractA new intumescent flame retardant (IFR) system consisting of ammonium polyphosphate (APP) and charing‐foaming agent (CFA) and a little organic montmorillonite (OMMT) was used in low‐density polyethylene (LLDPE)/ethylene‐vinyl acetate (EVA) composite. According to limiting oxygen index (LOI) value and UL‐94 rating obtained from this work, the reasonable mass ratio of APP to CFA was 3 : 1, and OMMT could obviously enhance the flame retardancy of the composites. Cone calorimeter (CONE) and thermogravimetric analysis (TGA) were applied to evaluate the burning behavior and thermal stability of IFR‐LLDPE/EVA (LLDPE/EVA) composites. The results of cone calorimeter showed that heat release rate peak (HRR‐peak) and smoke production rate peak (SPR‐peak) and time to ignition (TTI) of IFR‐LLDPE/EVA composites decreased clearly compared with the pure blend. TGA data showed that IFR could enhance the thermal stability of the composites at high temperature and effectively increase the char residue. The morphological structures of the composites observed by scanning electron microscopy (SEM) and X‐ray diffraction (XRD) demonstrated that OMMT could well disperse in the composites without exfoliation, and obviously improve the compatibility of components of IFR in LLDPE/EVA blend. The morphological structures of char layer obtained from Cone indicated that OMMT make the char layer structure be more homogenous and more stable. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009