bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preliminary study on preparation of unsaturated polyester resin/natural rubber latex blends in the presence of dispersion aids
Authors: Pachpinyo P. , Lertprasertpong P. , Chuayjuljit S. , Sirisook R. , Pimpan V. 
Published: June 2006

AbstractThe objective of this research was to study the possibility of blending unsaturated polyester resin (UPE resin) with 5, 10, and 15 parts per hundred resin (phr) natural rubber latex (NRL) in the presence of dispersion aids in order to improve the impact resistance of UPE resin. Three types of dispersion aids, sodium lauryl sulfate (SLS), toluene, and ammonia, were used in this study in amounts of 10, 15, 20 and 25 wt % of the NRL. These blended mixtures were cured at room temperature using methyl ethyl ketone peroxide (MEKPO) as an initiator and cobalt octoate as an accelerator. It was found that, regardless of the type of dispersion aid, the impact strength of blended UPE samples was higher than that of the pure UPE samples, and at 20 wt % toluene in 15‐phr NRL, the sample had the highest impact strength. However, because of low elastic modulus, characteristic of NRL, the tensile strength and flexural strength of the blended samples decreased as the NRL content of the blends increased. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 4238–4241, 2006
Diffusion coefficient of DMF in acrylic fiber formation
Authors: Hou Chen , Qu Rongjun , Wang Chunhua , Ying Liang 
Published: June 2006

AbstractA H2O/dimethyl formamide (DMF) mixture was used as the coagulation bath of wet‐spun process for acrylic fibers. Diffusion coefficient of DMF in the protofibers prepared by acrylonitrile/acrylamide copolymers was determined. It has been found that diffusion coefficient of DMF outflow of the protofibers prepared by acrylonitrile/acrylamide copolymers synthesized by solution polymerization is highest compared with those of acrylonitrile/acrylamide copolymers synthesized by H2O/DMF mixture suspension polymerization and aqueous suspension polymerization. With an increase of copolymer concentration in the dope, diffusion coefficient of DMF decreases continuously. Diffusion coefficient of DMF increases along with the bath temperature, but the changes in diffusion coefficient values are less prominent as temperature goes beyond 55°C. When DMF concentration in the coagulation bath was 50%, the value of the diffusion coefficient of DMF was minimal. Diffusion coefficient of DMF increases along with jet stretch minus ratio increase. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3616–3619, 2006
Reactive blending approach to modify spin‐coated epoxy film: Part II. Crosslinking kinetics
Authors: Turunen Markus P. K. , Laurila Tomi , Kivilahti Jorma K. 
Published: June 2006

AbstractKinetics of the reactive blending of epoxy with a four‐armed ϵ‐caprolactone‐based carboxylic acid end‐functionalized oligomer was analyzed with a model‐free approach. The employment of a dual catalyst system ensured high density of crosslinking in the blends and minimized phase separation even when comparatively high concentration of the oligomer was incorporated. The two reactions were examined separately before analysis of the dual‐catalyzed system. The apparent activation energy of the single‐catalyzed reactions could be seen to fall into three regimes. It is proposed that regime I is due to reaction control, the middle part (II) to mass transport, and the high conversion tail (III) to structural control. The results of a thermal analysis carried out on the crosslinked samples corresponded well with the findings of the kinetic analysis. The combined kinetic and thermal results can be used in optimization of the crosslinking process. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3689–3696, 2006
Reactive blending approach to modify spin‐coated epoxy film: Part I. Synthesis and characterization of star‐shaped poly(ϵ‐caprolactone)
Authors: Turunen Markus P. K. , Laurila Tomi , Kivilahti Jorma K. 
Published: June 2006

AbstractTo effectively modify the properties of an epoxy, branched oligomers were synthesized from ϵ‐caprolactone (CL) and end‐functionalized to realize network precursors that can be reactively blended with the epoxy. The ring‐opening polymerization (ROP) of the CL in the presence of polyglycerol (PGL) initiator (3.9 and 9.1 mol %) and Sn(II) 2‐ethylhexanoate catalyst yielded oligomers with hydroxyl end‐groups, which were converted to carboxylic acid functionality by reaction with succinic anhydride. The functionalized oligomers had a four‐armed structure and the molecular weight of the oligomers could be controlled by the ratio of CL to PGL in the feed. To achieve an adequately crosslinked network in the reactive blending, a dual‐catalyzed reaction scheme was employed. First the oligomer was incorporated into the epoxy matrix in an imidazole‐catalyzed reaction and then the crosslinking was completed with an acid‐catalyzed ROP of the residual epoxies. Investigations showed that toughened coatings could be prepared from the inherently brittle epoxy through proper choice of the blending ratio of oligomer to epoxy. The blending increased surface hydrophobicity at high concentrations of functionalized oligomer, but did not have an adverse effect on the inherently advantageous endothelial cell spreading. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3677–3688, 2006
Preparation of poly(methyl methacrylate)/titanium oxide composite particles via in‐situ emulsion polymerization
Authors: Yang Mingjiao , Dan Yi 
Published: June 2006

AbstractPoly(methyl methacrylate) (PMMA)/Titanium oxide (TiO2) composite particles were prepared via in‐situ emulsion polymerization of MMA in the presence of TiO2 particles. Before polymerization, the TiO2 particles was modified by the silane coupling agent, which is crucial to ensure that PMMA reacts with TiO2 via covalent bond bindings. The structure of the obtained PMMA/TiO2 composite particles was characterized using Fourier transform infrared spectra (FTIR) and thermogravimetric analysis (TGA). The results indicate that there are covalent bond bindings between PMMA macromolecules and TiO2 particles. Based on these facts, several factors affecting the resulting PMMA/TiO2 composite system, such as the type of coupling agents, the mass ratio of the MMA to the modified TiO2, the emulsifier concentration, and the initiator concentration, etc., were examined by the measurement of conversion of monomers, the gel content of polymers, the percentage of grafting, and the grafting efficiency, using gravity method or TGA method. As a result, the optimized recipe was achieved, and the percentage of grafting and the grafting efficiency could reach 216.86 and 96.64%, respectively. In addition, the obtained PMMA/TiO2 composite particles were found to a stable colloidal dispersion in good solvent for PMMA. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 4056–4063, 2006
Chitosaneous hydrogel beads for immobilizing neutral protease for application in the preparation of low molecular weight chitosan and chito‐oligomers
Authors: Li Jin , Du Yumin , Sun Liping , Liang Hongbo , Feng Tao , Wei Yuan'an , Yao Pinjia 
Published: June 2006

AbstractEnzyme hydrolysis with immobilized neutral protease was carried out to produce low molecular weight chitosan (LMWC) and chito‐oligomers. Neutral protease was immobilized on (CS), carboxymethyl chitosan (CMCS), and N‐succinyl chitosan (NSCS) hydrogel beads. The properties of free and immobilized neutral proteases on chitosaneous hydrogel beads were investigated and compared. Immobilization enhanced enzyme stability against changes in pH and temperature. When the three different enzyme supports were compared, the neutral protease immobilized on CS hydrogel beads had the highest thermal stability and storage stability, and the enzyme immobilized on NSCS hydrogel beads had the highest activity compared to those immobilized on the other supports, despite its lower protein loading. Immobilized neutral protease on all the three supports had a higher Km (Michaelis‐Menten constant) than free enzyme. The Vmax (maximum reaction velocity) value of neutral protease immobilized on CS hydrogel beads was lower than the free enzyme, whereas the Vmax values of enzyme immobilized on CMCS and NSCS hydrogel beads were higher than that of the free enzyme. Immobilized neutral protease on CS, CMCS, and NSCS hydrogel beads retained 70.4, 78.2, and 82.5% of its initial activity after 10 batch hydrolytic cycles. The activation energy decreased for the immobilization of neutral protease on chitosaneous hydrogel beads. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3743–3750, 2006
Effects of hydrophobic interaction on rheological behavior and microstructure of carboxylated core‐shell latex suspension
Authors: Nakamura Hiroshi , Tachi Kazuyuki 
Published: June 2006

AbstractWe have investigated the effects of hydrophobic interactions on the rheological behavior and microstructure of suspension of carboxylated core‐shell latex particles with changing hydrophobicity of shell polymer and suspending medium. The carboxylated core‐shell latex particles formed lattice‐like microstructures in aqueous suspension with dissociation of carboxyl groups. With increasing hydrophobicity of the shell polymer, the interparticle distance ξ in the microstructure decreased. However, ξ increased with increasing hydrophobicity of the suspending medium. The effect of hydrophobic interaction on ξ was explained by the steric stabilization theory for particles with grafted polymer on the surface. As the carboxylated core‐shell latex particles overlapped each other in the microstructure, an attractive force was generated between the particles in aqueous suspension. With increasing hydrophobicity of the shell, the attractive force increased, but with increasing hydrophobicity of the suspending medium, the attractive force decreased. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 4153–4158, 2006
Preparation, morphology, and properties of multilamellar barrier materials based on blends of high‐density polyethylene and copolyester
Authors: Cui Xiuguo , Wang Xiaodong 
Published: June 2006

AbstractThe multilamellar barrier materials based on the blends of high‐density polyethylene (HDPE) and copolyester (PETG) were prepared via melt extrusion, and poly(ethylene‐co‐acrylic acid) (EAA) as a compatibilizer was incorporated into the blends. A systematic investigation was carried out, with regard to morphology and properties. Scanning electron microscopy observation displayed the laminar morphology for the blends with the whole compositions, and the thinner laminas of the PETG phase formed in the HDPE matrix by incorporating EAA into the blends. In addition, the number and the size of the laminas of the dispersed phases were also dependant on the die temperature and screw speed, respectively. Evaluation of the mechanical properties demonstrated that incorporation of the EAA resulted in an improvement of the mechanical properties. These behaviors are attributed mainly to better adhesion and compatibility between HDPE and PETG, which has been confirmed by thermal analysis and the rheological properties. On the basis of these premises, it is reasonable to suggest that the improved barrier properties of the ternary blends with increasing concentration of the EAA be attributed to both the increase in the number of the laminas of the PETG and the decrease in their thickness, which prohibits the organic solvent molecules from entering into and permeating through the amorphous regions of the blends. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3791–3799, 2006
Polymerization of norbornene using bis(β‐ketoamino)nickel(II)/MAO catalytic systems
Authors: He Xiaohui , Wu Qing 
Published: June 2006

AbstractThe polymerizations of norbornene were investigated using a series of bis(β‐ketoamino)nickel(II) complexes(1–6) in combination with methylaluminoxane (MAO) in toluene solution. The effects of catalyst structure, Al/Ni molar ratio, reaction temperature, and reaction time on catalytic activity and molecular weight of the polynorbornene were examined in detail. The electronic effect of the substituent around the imino group in the ligand is stronger than the steric bulk one on the polymerization activities, and the activities are in the order of 1 > 2 > 4 > 5 > 6 > 3. The obtained polynorbornenes were characterized by means of 1H‐NMR, 13C‐NMR, FTIR, TG, and WAXD techniques. The analyses results of polymers' structures and properties indicate that the polymerization reaction of norbornene runs in vinyl‐addition polymerization mode. The obtained polynorbornene was confirmed to be vinyl‐type and atactic polymers and showed good thermostability (Tdec > 458°C) and were noncrystalline but had short‐range order. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 4172–4180, 2006
Preparation of polyacrylate‐clay nanocomposites by in‐situ polymerization and heterocoagulation
Authors: Xu Yijin , Brittain William J. 
Published: June 2006

AbstractPolyacrylate‐clay nanocomposites were prepared by an in situ polymerization method followed by heterocoagulation. In the heterocoagulation method, a cationic polyacrylate emulsion was prepared by emulsion polymerization using a cationic initiator in the presence/absence of free surfactant, cetyl trimethylammonium bromide (CTABr), followed by mixing with an aqueous clay slurry. WAXD results and TEM images suggest that morphologies of these nanocomposites depend on preparation method, mixing method, and the amount of free surfactant. TG‐DTG analyses demonstrate the improvement in thermal stability of these nanocomposites, while DSC results indicate no significant changes in glass transition temperature of these nanocomposites. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3850–3855, 2006
Control of biodegradability of poly(3‐hydroxybutyric acid) film with grafting acrylic acid and thermal remolding
Authors: Wada Yuki , Mitomo Hiroshi , Kasuya Ken‐Ichi , Nagasawa Naotsugu , Seko Noriaki , Katakai Akio , Tamada Masao 
Published: June 2006

AbstractRadiation‐induced graft polymerization of acrylic acid (AAc) on poly(3‐hydroxybutyric acid) (PHB) film was carried out and the resulting film was thermally‐remolded. The PHB films grafted with AAc (PHB‐g‐AAc) having a degree of grafting higher than 5% completely lost the enzymatic degradability. The enzymatic degradability of the grafted film was recovered by thermal remolding. The highest enzymatic degradation rate was observed at degree of grafting of 10% after thermal remolding. The PHB‐g‐AAc films and thermally‐remolded PHB‐g‐AAc films were characterized by contact angle and differential scanning calorimetry. The enzymatic degradability of PHB‐g‐AAc films was lost by the grafted AAc, which covered the surface of PHB film. The acceleration of enzymatic degradation in the remolded PHB‐g‐AAc films was mainly caused by decrease of crystallinity of PHB by dispread of grafted AAc during thermal remolding. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3856–3861, 2006
Regulation of JNK by MKK‐7 in fibroblast‐like synoviocytes
Authors: Inoue Tomoyuki , Hammaker Deepa , Boyle David L. , Firestein Gary S. 
Published: June 2006

AbstractObjectiveJNK regulates matrix metalloproteinase (MMP) gene expression and joint destruction in rheumatoid arthritis (RA). Previous studies demonstrated that the 2 upstream MAPK kinases (MKK‐4 and MKK‐7) are phosphorylated in RA synovium and form a complex with JNK in fibroblast‐like synoviocytes (FLS). However, the functional hierarchy of MKK‐4 and MKK‐7 in FLS has not been determined. We determined the relative contributions of these MKKs by evaluating the effect of MKK‐4 and MKK‐7 gene knockdown in cultured FLS.MethodsFLS were transfected with MKK‐4 and/or MKK‐7 small interfering RNA, and protein levels were determined by immunoblotting. After stimulation with interleukin‐1β (IL‐1β), tumor necrosis factor α (TNFα), or anisomycin, kinase function was determined by in vitro kinase assay. Activator protein 1 (AP‐1) binding and transcriptional activity were determined by electrophoretic mobility shift assay and AP‐1–luciferase promoter assay, respectively. MMP‐3 expression was determined by enzyme‐linked immunosorbent assay and quantitative polymerase chain reaction.ResultsIL‐1β–induced JNK phosphorylation was dependent on MKK‐7 but not on MKK‐4; however, anisomycin‐activated JNK required both kinases. In vitro kinase assay demonstrated that IL‐1β– or TNFα‐induced JNK activity was only MKK‐7 dependent, while anisomycin‐activated JNK was both MKK‐4 and MKK‐7 dependent. IL‐1β–induced AP‐1 binding activity and AP‐1–driven gene expression were strictly MKK‐7 dependent. Finally, MMP‐3 production only required MKK‐7, and there was no effect of MKK‐4 deficiency.ConclusionThese data indicate that only MKK‐7 is required for JNK activation in FLS after cytokine stimulation; however, other forms of cellular stress utilize MKK‐4. Thus, JNK function might be modulated by targeting MKK‐7 to suppress cytokine‐mediated FLS activation while leaving other stress responses intact.
Differential survival of leukocyte subsets mediated by synovial, bone marrow, and skin fibroblasts: Site‐specific versus activation‐dependent survival of T cells and neutrophils
Authors: Filer Andrew , Parsonage Greg , Smith Emily , Osborne Chloe , Thomas Andrew M. C. , Curnow S. John , Rainger G. Ed , Raza Karim , Nash Gerard B. , Lord Janet , Salmon Mike , Buckley Christopher D. 
Published: June 2006

AbstractObjectiveSynovial fibroblasts share a number of phenotype markers with fibroblasts derived from bone marrow. In this study we investigated the role of matched fibroblasts obtained from 3 different sources (bone marrow, synovium, and skin) to test the hypothesis that synovial fibroblasts share similarities with bone marrow–derived fibroblasts in terms of their ability to support survival of T cells and neutrophils.MethodsMatched synovial, bone marrow, and skin fibroblasts were established from 8 different patients with rheumatoid arthritis who were undergoing knee or hip surgery. Resting or activated fibroblasts were cocultured with either CD4 T cells or neutrophils, and the degree of leukocyte survival, apoptosis, and proliferation were measured.ResultsFibroblasts derived from all 3 sites supported increased survival of CD4 T cells, mediated principally by interferon‐β. However, synovial and bone marrow fibroblasts shared an enhanced site‐specific ability to maintain CD4 T cell survival in the absence of proliferation, an effect that was independent of fibroblast activation or proliferation but required direct T cell–fibroblast cell contact. In contrast, fibroblast‐mediated neutrophil survival was less efficient, being independent of the site of origin of the fibroblast but dependent on prior fibroblast activation, and mediated solely by soluble factors, principally granulocyte–macrophage colony‐stimulating factor.ConclusionThese results suggest an important functional role for fibroblasts in the differential accumulation of leukocyte subsets in a variety of tissue microenvironments. The findings also provide a potential explanation for site‐specific differences in the pattern of T cell and neutrophil accumulation observed in chronic inflammatory diseases.
Regulation of pre–B cell colony‐enhancing factor by STAT‐3–dependent interleukin‐6 trans‐signaling: Implications in the pathogenesis of rheumatoid arthritis
Authors: Nowell Mari A. , Richards Peter J. , Fielding Ceri A. , Ognjanovic Simona , Topley Nick , Williams Anwen S. , Bryant‐Greenwood Gillian , Jones Simon A. 
Published: June 2006

AbstractObjectiveTo determine whether interleukin‐6 (IL‐6) trans‐signaling directs the expression of pre–B cell colony‐enhancing factor (PBEF) in vitro and in vivo.MethodsComplementary DNA from rheumatoid arthritis (RA) synovial fibroblasts treated with IL‐6 and soluble IL‐6 receptor (sIL‐6R) was used to probe a cytokine microarray. PBEF regulation by the IL‐6–related cytokines, IL‐6, sIL‐6R, oncostatin M (OSM), IL‐11, and leukemia inhibitory factor (LIF) was determined by reverse transcription–polymerase chain reaction analysis. IL‐6–mediated STAT‐3 regulation of PBEF was determined using a cell‐permeable STAT‐3 inhibitor peptide. Antigen‐induced arthritis (AIA) was induced in wild‐type (IL‐6+/+) and IL‐6–deficient (IL‐6−/−) mice. PBEF and STAT were detected by immunohistochemistry, immunoblotting, and electrophoretic mobility shift assay. Synovial levels of PBEF were quantified by enzyme immunoassay.ResultsIL‐6 trans‐signaling regulated PBEF in a STAT‐3–dependent manner. In addition, PBEF was regulated by the IL‐6–related cytokine OSM, but not IL‐11 or LIF. Flow cytometric analysis of the IL‐6–related cognate receptors suggested that OSM regulates PBEF via its OSM receptor β and not its LIF receptor. The involvement of PBEF in arthritis progression was confirmed in vivo, where induction of AIA resulted in a 4‐fold increase in the synovial expression of PBEF. In contrast, little or no change was observed in IL‐6−/− mice, in which the inflammatory infiltrate was markedly reduced and synovial STAT‐1/3 activity was also impaired. Analysis of human RA synovial tissue confirmed that PBEF immunolocalized in apical synovial membrane cells, endothelial cells, adipocytes, and lymphoid aggregates. Synovial fluid levels of PBEF were significantly higher in RA patients than in osteoarthritis patients.ConclusionExperiments presented herein demonstrate that PBEF is regulated via IL‐6 trans‐signaling and the IL‐6–related cytokine OSM. PBEF is also actively expressed during arthritis. Although these data confirm an involvement of PBEF in disease progression, the consequence of its action remains to be determined.
The catabolic pathway mediated by Toll‐like receptors in human osteoarthritic chondrocytes
Authors: Kim Hyun Ah , Cho Mi‐La , Choi Hye Young , Yoon Chang Sik , Jhun Joo Yeon , Oh Hey Jwa , Kim Ho‐Youn 
Published: June 2006

AbstractObjectiveTo examine the catabolic pathways mediated by Toll‐like receptor (TLR) ligands in human osteoarthritic (OA) chondrocytes.MethodsThe presence of TLRs in OA and non‐OA articular cartilage was analyzed by immunohistochemistry. The regulation of TLR messenger RNA (mRNA) by interleukin‐1 (IL‐1) and tumor necrosis factor α (TNFα) was analyzed by reverse transcription–polymerase chain reaction. For stimulation of TLR‐2 and TLR‐4, chondrocytes were treated with Staphylococcus aureus peptidoglycan and lipopolysaccharides (LPS), respectively. Production of matrix metalloproteinases (MMPs) 1, 3, and 13 and prostaglandin E2 (PGE2) was evaluated by enzyme‐linked immunosorbent assay. Production of nitric oxide (NO) was analyzed by the Griess reaction. Regulation of cyclooxygenase 2 protein and phosphorylation of MAPKs (p38, ERK, and JNK) were evaluated by Western blotting or solid‐phase kinase assay. NF‐κB activation was evaluated by electrophoretic mobility shift assay.ResultsExpression of TLRs 2 and 4 was up‐regulated in lesional areas of OA cartilage. Treatment with IL‐1, TNFα, peptidoglycan, and LPS all significantly up‐regulated TLR‐2 mRNA expression in cultured chondrocytes. Production of MMPs 1, 3, and 13 and of NO and PGE2 was significantly increased after treating chondrocytes with either of the TLR ligands. Prolonged culture of cartilage explants with TLR ligands also led to a significant increase in the release of proteoglycan and type II collagen degradation product. Treatment with TLR ligands led to phosphorylation of all 3 MAPKs and activation of NF‐κB.ConclusionWe found that TLRs are increased in OA cartilage lesions. TLR‐2 and TLR‐4 ligands strongly induce catabolic responses in chondrocytes. Modulation of TLR‐mediated signaling as a therapeutic strategy would require detailed elucidation of the signaling pathways involved.