bluuebunny/crossref_metadata_2025_split huggingface dataset:
Positive temperature coefficient and time‐dependent resistivity of carbon nanotubes (CNTs)/ultrahigh molecular weight polyethylene (UHMWPE) composite
Authors: Gao Jie‐Feng , Yan Ding‐Xiang , Huang Hua‐Dong , Dai Kun , Li Zhong‐Ming 
Published: June 2009

AbstractThe carbon nanotubes/ultrahigh molecular weight polyethlene (CNTs/UHMWPE) conductive composite with a low percolation threshold had been successfully fabricated, and CNTs were only dispersed in the interface of matrix particles. Some factors, including CNTs concentration, processing temperature, and the time of isothermal treatment, which could exert influence on the positive temperature coefficient effect of the composite, were investigated. Similar with negative temperature coefficient effect, the resistivity decreased during isothermal treatment above the melting point of UHMWPE, which could be thought to be a relaxation process originated from movement of molecular chains. This relaxation, also a process of CNTs aggregating to reorganize the conductive network, was testified as a function of time, temperature, filler concentration, and heating rate. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Structural and mechanical behavior of layered zirconium phosphonate as a distributed phase in polycaprolactone
Authors: Furman Benjamin R. , Wellinghoff Stephen T. , Laine Richard M. , Chan Kwai S. , Nicolella Daniel P. , Rawls H. Ralph 
Published: June 2009

AbstractMixed‐surface octyl/methoxyundecyl α‐zirconium phosphonates (ZrPs) were investigated as distributed nanoscale fillers, in concentrations up to 50% w/w, for the purpose of increasing the elastic modulus and yield strength of polycaprolactone (PCL) without a meaningful reduction of its ductility. The volumetric nanoparticle loadings were estimated to be over 70% higher than those in nanocomposites with comparable weight fractions of nanoclay. The mechanical properties of the ZrP/PCL nanocomposite were evaluated with tensile, flexural, and dynamic mechanical testing methods. Nanocomposites containing 5% w/w ZrP showed significant increases in both the tensile yield stress and elastic modulus without any loss of ductility versus the unfilled polymer. Layer delamination from the ZrP tactoids was minimal. Kinetic barriers and the strong interlayer attraction between the ZrP surfaces limited intercalative penetration of the ZrP tactoids. ZrP loadings of 20% w/w or more resulted in the agglomeration of tactoids, leading to defect structures with a loss of strength and, at the highest loading, ductility. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
The effects of soft‐segment molecular weight and organic modifier on properties of organic‐modified MMT‐PU nanocomposites
Authors: Wang Chia‐Hao , Shieh Yeong‐Tarng , Nutt Steven 
Published: June 2009

AbstractThe effects of soft‐segment molecular weight and organic modification of montmorillonite (MMT) on thermal and mechanical properties of segmented polyurethane (PU) elastomers were investigated. The PU/MMT nanocomposites were prepared by in situ polymerization, and the compositions included soft segments with number average molecular weights of 1000, 2000, and 2900, and organic‐modified MMT (including MMT‐30B and MMT‐I30E). The nanocomposites produced were characterized using wide‐angle X‐ray diffraction (WAXD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and mechanical testing. The TEM and XRD results revealed that both MMT‐30B and MMT‐I30E were intercalated, and partially exfoliated by the PU. Mechanical tests showed that the PU1000 series in soft‐segment molecular weight yielded superior tensile properties compared with the PU2000 and PU2900 series. Also, for a given molecular weight of soft segment in PU, the MMT‐30B nanocomposites exhibited greater increases in Young's modulus, tensile strength, and elongation at break than the MMT‐I30E counterpart, and the crystallinity of PU was enhanced by the clays. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
A new method to determine monomer concentration in the polymer particles of emulsion polymerization systems by dynamic light scattering
Authors: Abdollahi Mahdi , Hemmati Mahmoud 
Published: June 2009

AbstractEmulsifier‐free emulsion polymerization of styrene was performed in the presence of small amount of methacrylic and itaconic acids as carboxylic acid monomers and potassium persulfate as an initiator at 70°C to prepare monodisperse polymer particles. Diameter of monomer swollen polymer particles (dpswol) was measured by dynamic light scattering for samples taken from the reaction mixture during the Intervals II and III of the emulsion polymerization. Graphically treatment of dpswol versus conversion data allowed us for the first time to directly determine the critical monomer conversion (xc), from which constant monomer concentration in the polymer particles (CMP) during the Interval II was then calculated. xc and CMP were obtained to be 0.379 and 5.68, respectively. CMP value is in good agreement with that obtained by centrifugation method and those reported in the literature for the similar system. Attempts were also made to evaluate the average number of growing chain per particle (
$\overline n$) during the Interval II of emulsion polymerization of styrene. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Study on macromolecular lanthanide complexes (V): Synthesis, characterization, and fluorescence properties of lanthanide complexes with the copolymers of styrene and acrylic acid
Authors: Liang Xing , Yang Ying , Jia Xue‐Qing , Niu Li‐e , Qi Xin‐Hua 
Published: June 2009

AbstractIn this study, the luminescent macromolecular lanthanide complexes Ln‐PSt/AA (Ln = Eu and Tb; St = styrene; AA = acrylic acid) have been synthesized, and an extensive characterization has been carried out by means of elemental analysis, FTIR, thermal analysis, and fluorescence determination. The results showed that the carboxylic groups on the chain of the polymers acted as bidentate ligands coordinated to lanthanide ions; and the coordination degree of COO−/Ln3+ in the macromolecular complexes was closely dependent on both the pH value of the solution and the molar ratio of St to AA in the polymeric ligands. Thermal analysis manifested that these Ln‐PSt/AA (Ln = Eu and Tb) complexes had high thermal stability and solvent resistance, and these macromolecular complexes were highly crosslinked. The fluorescence determination indicated that Ln‐PSt/AA complexes could emit characteristic fluorescence with comparatively high brightness and good monochromaticity, and the fluorescence intensity changed with increasing lanthanide ions content. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Preparation and properties of waterborne interpenetrating polymer networks composed of polyurethaneurea and graft vinyl ester resin
Authors: Su Teng , Hu Chun Pu 
Published: June 2009

AbstractVarious waterborne interpenetrating polymer networks (IPNs) composed of polyurethaneurea (PUU) and graft vinyl ester resin were prepared from polyester polyol, dimethylolpropionic acid, isophorone diisocyanate, ethylenediamine and a well‐defined graft vinyl ester resin containing butanol side chains (BO‐g‐VER). These anionic IPN aqueous dispersions were stable at the ambient temperature for >1 yr, and also had the excellent stability at low and high temperatures. The experimental results showed that the introduction of BO‐g‐VER network has not only greatly affected the particle morphology, stability and rheological behavior of these aqueous dispersions, but also rendered the films with the augmented surface hydrophobicity as well as the excellent water‐resistance performance and mechanical properties. A synergistic effect was observed at a certain BO‐g‐VER composition (20 wt %) to give significant reinforcement to the PUU, resulting from the compatibility and/or the interpenetration between the PUU network and the BO‐g‐VER network. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
A series of 0‐3 composites of lead zirconate titanate and ferroelectric nylon77: Preparation and electrical properties
Authors: Petchsuk A. , Supmak W. , Thanaboonsombut A. 
Published: June 2009

AbstractA series of 0‐3 composites of lead zirconate titanate (PZT) and nylon77 was prepared with PZT volume fractions between 0.1 and 0.6 using the combined method of solvent casting and hot pressing. Depending upon the volume fraction of PZT, the relative permittivities of the composites were found to be in the range of 200–2000 when measured at the highest practically possible temperature of 200°C. As PZT volume fraction increases, both the relative permittivity and the piezoelectric constant d33 increase. The best combination of electrical properties and flexibility was obtained in 0.5 PZT volume fraction composites. At this composition, the remanent polarization Pr of composites was up to 1000 mC/m2 at the applied electric field of 40 MV/m and it increased with an increase in temperature. The highest piezoelectric strain coefficient d33 was obtained at 17 pC/N in 0.6 PZT volume fraction composites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Synthesis and characteristics of a silicon‐containing polymer, manufacture of an electrolyte membrane from the polymer and poly(vinylidene fluoride‐co‐hexafluoropropene), and property testing of the membrane
Authors: Ye Lin , Ju Ling , Wu Chuan , Feng Ting , Mo Wei , Wu Feng , Bai Ying , Feng Zeng‐guo 
Published: June 2009

AbstractA silicone‐containing polymer was synthesized by addition polymerization between 1,12‐bis(3‐methyl‐3‐oxetanyl)‐2,5,8,11‐tetraoxadodecane and dichloride dimethylsilane catalyzed by tetrabutylammonium bromide and was characterized by Fourier transform infrared spectroscopy, 1H‐NMR, gel permeation chromatography, and differential scanning calorimetry analyses. To manufacture a tough solid electrolyte membrane, various amounts of a poly(vinylidene fluoride‐co‐hexafluoropropene) copolymer was used to reinforce this silicone‐containing polymer. The mechanical properties and compatibility of the resulting membranes were assessed by mechanical testing and scanning electron microscopy observation. The ionic conductivity was assayed from an alternating‐current impedance spectrum. The results reveal that the maximum ionic conductivity reached 7.4 × 10−5 S/cm at 30°C and 2.6 × 10−4 S/cm at 80°C, respectively. Additionally, the linear sweep voltammetry tests showed that this kind of the blended polymer electrolyte was electrochemical stable until 4.3 V. The thermogravimetric analysis measurements also implied its good thermal stability. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Homopolymerization effects in polymer layered silicate nanocomposites based upon epoxy resin: Implications for exfoliation
Authors: Pustkova Pavla , Hutchinson John M. , Román Frida , Montserrat Salvador 
Published: June 2009

AbstractExfoliation of polymer layered silicate nanocomposites based upon epoxy resin has previously been reported to be enhanced by allowing some homopolymerization of the resin to occur, catalyzed by the onium ion of the organically modified clay, before the addition of the cross‐linking agent and the curing of the nanocomposite. In this work we examine the effects of homopolymerization induced by pre‐conditioning the resin/clay mixtures by storing them at various temperatures, from room temperature to 100°C, prior to curing. It is found that pre‐conditioning results in similar increases in both the epoxy equivalent (EE) and the glass transition temperature (Tg) of the resin as a consequence of homopolymerization, with a linear relationship between EE and Tg that depends on the pre‐conditioning temperature. This is attributed to two different homopolymerization reaction mechanisms, activated monomer (AM) and activated chain end (ACE), the former dominating at high temperature and the latter at low temperature. The effects of these homopolymerization reactions on the network and nanostructure of the nanocomposite are discussed, the important aspect emerging being that the ACE mechanism is the one that most significantly enhances the exfoliation process. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Wood‐thermoplastic composites from wood flour and high‐density polyethylene
Authors: Xiong Cheng , Qi Rongrong , Wang Yanling 
Published: June 2009

AbstractHigh‐density polyethylene/wood flour (HDPE/WF) composites were prepared by a twin‐screw extruder. The effects of WF, silane coupling agents, polymer compatibilizers, and their content on the comprehensive properties of the WF/HDPE composites have been studied in detail, including the mechanical, thermal, and rheological properties and microstructure. The results showed that both silane coupling agents and polymer compatibilizers could improve the interfacial adhesion between WF and HDPE, and further improve the properties of WF/HDPE composites, especially with AX8900 as a compatibilizer giving higher impact strength, and with HDPE‐g‐MAH as a compatibilizer giving the best tensile and flexural properties. The resultant composite has higher strength (tensile strength = 51.03 MPa) and better heat deflection temperature (63.1°C). © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Copolymerization of α‐cyanovinyl acetate with acrylonitrile and methacrylonitrile: Synthesis, characterization, and study of their dielectric behavior
Authors: Arous Mourad , Kallel Ali , Kaddami Hamid , Lahcini Mohamed , Belfkira Ahmed , Raihane Mustapha 
Published: June 2009

AbstractIn the frame of a research aiming at developing new dielectric polymers containing CCN substituent with strong dipole moment, the radical copolymerization of cyano (nitrile) monomers and an α‐cyanovinyl acetate (CVA) as the comonomer, initiated by AIBN is described. Methacrylonitrile (MAN) and acrylonitrile (AN) were chosen as the cyano monomers. The homopolymer of CVA was also prepared and the corresponding yield was close to 60%. All these polymers were characterized by 13C NMR, IR, DSC, and TGA. The percentages of incorporation of AN and MAN in the copolymers were 36 and 56%, respectively. These products showed high glass transition temperatures, Tg, ranging between 124 and 142°C. The thermogravimetry analyses showed that these copolymers are stable up to 200°C. Dielectric spectroscopy analysis revealed a weak relaxation β process below Tg. The α relaxation phenomena have also been characterized around the Tg and associated to the cooperative movements of the polar groups (CN). The values of dielectric relaxation increment were calculated at 150°C using the Havriliak–Negami equation and indicated that these polymers exhibit interesting dielectric properties comparatively to similar cyano materials. The α‐activation energies were also calculated. New statistic copolymers based on CVA were characterized. The values of the intensity of α relaxation show the potential application of such materials in the domain of electronics. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Expression of Hepatocyte Growth Factor and Basic Fibroblast Growth Factor as Prognostic Indicators in Gastric Cancer
Authors: Zhang Wei , Chu Yong‐Quan , Ye Zai‐Yuan , Zhao Zhong‐Sheng , Tao Hou‐Quan 
Published: June 2009

AbstractWe have investigated the correlations among hepatocyte growth factor (HGF) mRNA expression, basic fibroblast growth factor (bFGF) mRNA expression, tumor microvessel density (MVD), and clinical pathological features of gastric cancer in Chinese patients. In situ hybridization was used to detect the expression of HGF and bFGF mRNAs, and immunohistochemistry was used to detect CD34 in 105 gastric cancer tissues and in 20 normal control tissues. The rate of HGF mRNA expression in normal gastric tissues (25%) was significantly lower than that (57.1%) in tumor tissues (P < 0.01). The rates of HGF mRNA and bFGF mRNA expression and MVD in T3–T4 stage tissues were higher than those in T1–T2 stage tissues (P < 0.01); the HGF mRNA expression rate was directly correlated with the bFGF mRNA expression rate (P < 0.05), and they were also directly correlated with MVD (P < 0.01). The mean survival time and the 5‐year survival rate of patients who were positive for expression of HGF mRNA and bFGF mRNA and who had a MVD ≥ 39.5/0.72 mm2 were significantly shorter than those who did not express HGF mRNA and bFGF mRNA and who had a MVD <39.5/0.72 mm2. Both HGF and bFGF may participate in angiogenesis in gastric cancer and may be involved in tumor invasion and metastasis. HGF and bFGF mRNA expression can be used as useful parameters to evaluate the prognosis of gastric cancer. Anat Rec, 2009. © 2009 Wiley‐Liss, Inc.
Role of allatostatin‐like factors from the brain of Tenebrio molitor females
Authors: Wasielewski O. , Skonieczna M. , Kodrík D. 
Published: June 2009

AbstractThe effect of brain extract from females of freshly emerged Tenebrio molitor on ovary, oocyte development, total protein content of hemolymph, and ovary was studied in 4‐day‐old adult mealworm females. Injections of extracts of 2‐brain equivalents into intact (unligatured) Tenebrio females did not affect ovarian and oocyte development. Injections of ligated females, however, with 2‐brain equivalents on day 1 and 2 after adult emergence strongly inhibited ovarian growth and oocyte development. At day 4, ligated and injected females did not develop their ovaries and pre‐vitellogenic oocytes were not found. The changes in ovarian development correlated with an increase in the concentration of soluble proteins in the hemolymph as compared with the saline‐injected controls. Additionally, a strong reduction of total protein content in ovarian tissue was observed. Reverse phase HPLC separation of a methanolic brain extract of T. molitor females showed that fraction 5 has a similar retention time to synthetic cockroach allatostatin. Fraction 5 was eluted at 12.88 min, which was closest to the internal standard Dippu‐AST I, which eluted at 12.77 min. An ELISA of fraction 5 from the methanolic brain extract using antibodies against allatostatins Grybi‐AST A1 and Grybi‐AST B1 from cricket Gryllus bimaculatus showed that fraction 5 cross‐reacted with Grybi‐AST A1 antibodies. The cross‐reactivity was similar to the synthetic allatostatin from D. punctata, which was used as a positive control. These observations demonstrate a possible role for allatostatin‐like brain factor(s) in regulating the reproductive cycle of Tenebrio molitor. © 2009 Wiley Periodicals, Inc.
An integrated inventory model with controllable lead time and distribution‐free demand
Authors: Hsu Shu‐Lu , Huang Yar‐Fen 
Published: June 2009

AbstractThe impact of lead time reduction on an integrated periodic review inventory system comprising a single vendor and multiple buyers with a step crashing cost function and service‐level constraints is studied. The probability distribution of demand during the protection period for each buyer is unknown, but the mean and the variance are given. Each production lot of the vendor can be delivered in a number of shipments to all buyers. A minimax distribution‐free procedure with Lagrange multipliers is applied to determining the lead time, the common shipment cycle time, the target levels of replenishments and the number of shipments per production cycle so that the expected total system cost is minimized. Numerical experiments along with sensitivity analysis were performed to illustrate the effects of parameters on the decision and the total system cost. Copyright © 2009 John Wiley & Sons, Ltd.
Green supply chains and the missing link between environmental information and practice
Authors: Solér Cecilia , Bergström Kerstin , Shanahan Helena 
Published: June 2009

AbstractWithin the field of green supply chain management (GSCM), an interest in supply chain cooperation to create sustainable competitive advantage, i.e. the collaborative paradigm, has made researchers turn their attention to information related aspects of the supply chain. This study contributes to an understanding of a suboptimal use of environmental information, which is critical for all collaborative efforts aiming at sustainable competitive advantage. The aim of this article is to describe the use of environmental information at different stages of the Swedish food supply chain. The results from this case study of the Swedish food supply chain indicate that environmental information is perceived and used differently by purchasers in the supply chain depending on where (in the supply chain) they are situated in relation to other chain actors. The main contribution of this study is the suggestion of a stage‐dependent connection between perceived environmental cost and perceived environmentally informed consumer demand, which are barriers to GSCM practice discussed in recent GSCM literature. The missing link between information sharing and (environmental) performance of supply chains is explained as distance to end‐consumer in terms of supply chain stages. Implications for GSCM practice and theory are discussed. Copyright © 2009 John Wiley & Sons, Ltd and ERP Environment.
Impulse‐based rigid body interaction in SPH
Authors: Oh Seungtaik , Kim Younghee , Roh Byung‐Seok 
Published: June 2009

AbstractA new boundary force is proposed to solve rigid body interaction in SPH (Smoothed Particle Hydrodynamics). The new boundary force is impulse‐based rather than potential‐based. The impulse is converted to a boundary force with a fundamental observation that the impulse is a momentum change which is a result of a force acting on an object during a time interval. Our new impulse‐based boundary force gives more stable and accurate results in all kinds of rigid body interactions, especially in rigid—rigid interaction since our boundary force faithfully reflects the dynamic features of rigid body. With our impulse‐based boundary force, SPH fluid solver is capable of full two way interaction of fluid and rigid body and it turns to be a particle‐based rigid body solver if only rigid bodies are simulated without fluid. Copyright © 2009 John Wiley & Sons, Ltd.
Photochemical Regulation of Restriction Endonuclease Activity
Authors: Young Douglas D. , Govan Jeane M. , Lively Mark O. , Deiters Alexander 
Published: June 2009

AbstractRemoval by the light: The photochemical regulation of restriction endonucleases, which are important enzymes in molecular biology, has been investigated. Photolabile protecting groups have been installed on DNA substrates and have been demonstrated to inhibit restriction endonuclease activity until removed by UV light irradiation. Interestingly, these groups do not appear to dramatically affect initial binding of the enzyme to the DNA substrate, but rather prevent recognition of the specific cleavage site.magnified image