bluuebunny/crossref_metadata_2025_split huggingface dataset:
Miscibility, crystallization behavior and specific intermolecular interactions in thermosetting polymer blends of novolac epoxy resin and polyethylene glycol
Authors: Qin Chen , Shen Jianfeng , Hu Yizhe , Huang Weishi , Ye Mingxin 
Published: January 2008

AbstractThermosetting polymer blends of novolac epoxy resin (EPN) and polyethylene glycol (PEG) were studied. The miscibility and crystallization behavior of the blends before curing reaction were investigated by polarized optical microscopy and differential scanning calorimetry (DSC). Overall uncured blend compositions were homogeneous in amorphous state. Single composition‐dependent glass‐transition temperature (Tg) for each blend could be observed, and the experimental Tg's of blends with EPN content ≥40 wt% could be explained well by the Gordon–Taylor equation. Thermal properties of blends cured with 4,4′‐diaminodiphenylmethane were also determined by DSC. The capability of PEG to crystallize in cured blends was different from that in uncured ones because of the topological effect of highly crosslinking structure. On the basis of Fourier transform infrared spectroscopy results, it was judged that there were intermolecular hydrogen‐bonding interactions between EPN and PEG in both cured and uncured blends. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
Polylactide‐pine wood flour composites
Authors: Pilla Srikanth , Gong Shaoqin , O'Neill Eric , Rowell Roger M. , Krzysik Andrzej M. 
Published: January 2008

AbstractBiobased and biodegradable polylactide (PLA)‐pine wood flour (PWF) composites were investigated as a means to reduce the overall material cost and tailor the material properties. The composites were prepared using a kinetic‐mixer and an injection molding machine. The tensile modulus of the PLA‐PWF composites increased with the PWF content whereas the toughness and strain‐at‐break decreased. The tensile strength remained the same irrespective of the PWF content (up to 40%). The storage modulus also increased with the PWF content. Additionally, composites containing PWF treated with silane showed higher storage modulus than those without the silane treatment. The area integration underneath the tan δ peaks decreased with increasing PWF, indicating that the PLA‐PWF composites exhibited more elastic behavior with increasing PWF. The degree of crystallinity of the PLA‐PWF composites increased significantly with the PWF content. Furthermore, the treatment of PWF with silane had a positive effect on its nucleating ability, as treated PLA‐PWF composites showed higher crystallinity compared with their untreated counterparts. The morphology of the fracture surfaces were studied using a scanning electron microscope. Finally, a Halpin‐Tsai analytical model to predict Young's modulus of PLA‐PWF composites was presented to compare the theoretical results with that of experimental results. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
Properties of recycled material containing poly(vinyl chloride), polypropylene, and calcium carbonate nanofiller
Authors: Andričić Branka , Kovačić Tonka , Klarić Ivka 
Published: January 2008

AbstractEven at low content, polypropylene significantly worsens mechanical properties of the recycled PVC composite, i.e. tensile strength at break and elongation at break. But, if small quantities of surface modified nanofiller calcium carbonate is added, an applicable composite that contains 10–30% of waste material can be made. It was determined that nanosized calcium carbonate lowers melting point of polypropylene, perhaps by changing its crystalline form and has no influence on thermooxidative degradation of poly(vinyl chloride). Addition of nanofiller slightly lowers the surface free energy of the composites what is more prone when the low content of polypropylene is present. The recovery of tensile strength and elongation at break occurs and those properties reach the highest value at about 6% of CaCO3. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
Thermomechanical behavior of epoxy resins modified with epoxidized vegetable oils
Authors: Jin Fan‐Long , Park Soo‐Jin 
Published: January 2008

AbstractBiobased epoxy materials were prepared from diglycidyl ether of bisphenol A (DGEBA) and epoxidized vegetable oils (EVOs) (epoxidized soybean oil and epoxidized castor oil) with a thermally latent initiator. The effects of EVO content on the thermomechanical properties of the EVO‐modified DGEBA epoxy resins were investigated using several techniques. Differential scanning calorimetry indicated that the cure reaction of the DGEBA/EVO systems proceeded via two different reaction mechanisms. Single and composition‐dependent glass transition temperature (Tg) mechanisms were observed for the systems after curing. The experimental values of Tg could be explained by the Gordon–Taylor equation [Gordon M and Taylor JS, J Appl Chem 2:493 (1952)]. The thermal stability of the systems decreased as the EVO content increased, due to the lower crosslinking density of the DGEBA/EVO systems. The coefficient of thermal expansion of the systems was found to increase linearly with increasing EVO content. This could be attributed to the fact that the degrees of freedom available for motions of the segments of the macromolecules in the network structure were enhanced by the addition of EVO. Copyright © 2008 Society of Chemical Industry
Two novel oligomers based on fluorene and pyridine: Correlation between the structures and optoelectronic properties
Authors: Jiang Hong‐Ji , Wang Hong‐Yu , Zhu Rui , Wan Jun‐Hua , Liu Feng , Feng Jia‐Chun , Wei Wei , Huang Wei 
Published: January 2008

AbstractTo investigate the fine optoelectronic difference of the target oligomers with or without peripheral fluorene moieties, two dumbbell‐shaped oligomers (F0 and F1) were designed and convergently prepared via Suzuki coupling reaction. The molecular structures of the oligomers were fully characterized by 1H NMR, 13C NMR, and MALDI‐TOF mass spectra, respectively. The absorption, photoluminescent behavior, and energy band gaps of the oligomers were examined through UV–vis, photoluminescent spectra and cyclic voltammetry. The experimental results demonstrate that the absorption and photoluminescent properties are little affected by molecular architecture, while the absolute photoluminescence quantum efficiency of films and energy band gaps derived from cyclic voltammetry in solution are strongly correlated with the molecular frameworks. The observed energy band gaps of oligomers are further validated by the different molecular orbital contours of the HOMO energy levels from theoretical calculations. Preliminary electroluminescent investigations for F1 have also been conducted and discussed. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1548–1558, 2008
Penultimate effect in radical copolymerization of 2‐trifluoromethylacrylates
Authors: Ito Hiroshi , Trinque Brian C. , Kasai Paul , Willson C. Grant 
Published: January 2008

AbstractElectron‐deficient 2‐trifluoromethylacrylates (TFMA) undergo radical copolymerization with electron‐rich norbornene derivatives, vinyl ethers, and styrene derivatives, which can be described by the penultimate model much better than by the commonly employed terminal model. In an attempt to directly observe the effect of the CF3 group in the penultimate unit on the radical reactivity, we employed the Giese's mercury method. 4,4,4‐Trifluorobutyl and n‐butyl radicals produced from respective alkylmercuric chlorides were competitively reacted with t‐butyl 2‐trifluoromethylacrylate (TBTFMA) and t‐butyl methacrylate (TBMA) and the products analyzed with gas chromatography. While TBTFMA has been found to be about 24times more reactive than TBMA toward the n‐butyl radical, the former is about 12 times more reactive than the latter toward the 4,4,4‐trifluorobutyl radical. Thus, the reactivity of the propagating radical toward TBTFMA in comparison with TBMA is suppressed by a factor of two when the penultimate unit has the CF3 group. We observed a sextet electron spin resonance of the TFMA propagating radical with a coupling constant of ca. 25 gauss between the β‐proton and β‐fluorine. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1559–1565, 2008
Synthesis, characterization, and electroluminescence of PPV copolymers containing electron and hole‐transporting units
Authors: Xun Shidi , Zhou Quanguo , Li Hongchao , Ma Dongge , Wang Lixiang , Jing Xiabin , Wang Fosong 
Published: January 2008

AbstractThree series of poly(phenylene vinylene) (PPV) derivatives containing hole‐transporting triphenylamine derivatives [N‐(4‐octoxylphenyl)diphenylamine, N,N′‐di(4‐octyloxylphenyl)‐N,N′‐diphenyl‐1,4‐phenylenediamine, and N,N′‐di(4‐octoxylphenyl)‐N,N′‐diphenylbenzidine] (donor) and electron‐transporting oxadiazole unit (2,5‐diphenyl‐1,3,4‐oxadiazole) (acceptor) in the main chain were synthesized by improved Wittig copolymerization. The resulting donor–acceptor (D‐A) polymers are readily soluble in common organic solvents, such as chloroform, dichloroethane, THF, and toluene. The polymers containing oxadiazole group exhibit good thermal stability with 5% weight loss above 400 °C. The intramolecular charge‐transfer was observed in these D‐A polymers. In comparison with corresponding polymers without oxadiazole unit, the single‐layer devices based on the D‐A polymers showed much improved electroluminescent properties, because of the balanced charge injection and transport. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1566–1576, 2008
Dimer effect on fractional polycondensation of poly(p‐oxybenzoyl)
Authors: Kimura Kunio , Shimizu Yasuo , Ichimori Toshimitsu , Kohama Shin‐ichiro , Yamazaki Shinichi , Yamashita Yuhiko 
Published: January 2008

AbstractSelective preparation of poly(p‐oxybenzoyl) (POB) crystals was examined from the viewpoint of a dimer effect on fractional polycondensation. Four different copolymerization systems were chosen as the combinations ofp‐acetoxybenzoic acid (p‐ABA),m‐acetoxybenzoic acid (m‐ABA), and their dimers. The crystals obtained from the copolymerization of the dimer ofp‐ABA (p‐ABAD) andm‐ABA contained only 3.1 mol % ofm‐oxybenzoyl moiety even at high content ofm‐oxybenzoyl moiety in feed (χf) of 40 mol %.p‐Oxybenzoyl homo‐oligomers were more rapidly formed fromp‐ABAD in the solution than fromp‐ABA, and they were crystallized to form the crystals with segregating co‐oligomers. While co‐oligomers containing morem‐oxybenzoyl moiety were formed in the solution, afterward they were unable to be phase‐separated because of higher miscibility. The further polycondensation proceeded in the precipitated crystal, and finally the POB crystal was selectively formed. Lower polymerization temperature and concentration enhanced the fractionability, and the POB crystals containing less than 1 mol %m‐oxybenzoyl moiety were prepared at χfof 30 mol %, 270 °C, and a concentration of 0.5%. The dimer effect on the fractional polycondensation was clearly observed. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1598–1606, 2008
Synthesis and characterization of a series of 2‐aminopyridine nickel(II) complexes and their catalytic properties toward ethylene polymerization
Authors: Huang Zengfang , Song Keming , Liu Fengshou , Long Jieming , Hu Hao , Gao Haiyang , Wu Qing 
Published: January 2008

AbstractA series of 2‐aminopyridine Ni(II) complexes bearing different substituent groups {(2‐PyCH2NAr)NiBr, Ar = 2,4,6‐trimethylphenyl (3a), 2,6‐dichlorophenyl (3b), 2,6‐dimethylphenyl (3c), 2,6‐diisopropylphenyl (3d), 2,6‐difluorophenyl (3e); (2‐PyCH2NHAr)2NiBr2, Ar = 2,6‐diisopropylphenyl (4a)} have been synthesized and investigated as precatalysts for ethylene polymerization in the presence of methylaluminoxane (MAO). High molecular weight branched polymers as well as short‐chain oligomers were simultaneously produced with these complexes. Enhancing the steric bulk of the ortho‐aryl‐substituents of the catalyst resulted in higher ratio of solid polymer to oligomer and higher molecular weight of the polymer. With ortho‐haloid‐substitution, the catalysts afforded a product with low polymer/oligomer ratio (3b) and even only oligomers (3e) in which C14H28 had the maximum content. Compared with complex 3d containing ionic ligand, complex 4a containing neutral ligand exhibited obviously low catalytic activity for ethylene polymerization. The molecular weight, molecular weight distribution, and microstructure of the resulted polymer were characterized by gel permeation chromatography and 13C NMR spectrogram. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1618–1628, 2008
Living cationic polymerization of 2‐adamantyl vinyl ether
Authors: Hashimoto Tamotsu , Makino Yusuke , Urushisaki Michio , Sakaguchi Toshikazu 
Published: January 2008

AbstractLiving cationic polymerization of 2‐adamantyl vinyl ether (2‐vinyloxytricyclo[3.3.1.1]3,7decane; 2‐AdVE) was achieved with the CH3CH(OiBu)OCOCH3/ethylaluminum sesquichloride/ethyl acetate [CH3CH(OiBu)OCOCH3/Et1.5AlCl1.5/CH3COOEt] initiating system in toluene at 0 °C. The number‐average molecular weights (Mn's) of the obtained poly(2‐AdVE)s increased in direct proportion to monomer conversion and produced the polymers with narrow molecular weight distributions (MWDs) (Mw/Mn = ∼1.1). When a second monomer feed was added to the almost polymerized reaction mixture, the added monomer was completely consumed and the Mn's of the polymers showed a direct increase against conversion of the added monomer. Block and statistical copolymerization of 2‐AdVE with n‐butyl vinyl ether (CH2CHOCH2 CH2CH2CH3; NBVE) were possible via living process based on the same initiating system to give the corresponding copolymers with narrow MWDs. Grass transition temperature (Tg) and thermal decomposition temperature (Td) of the poly(2‐AdVE) (e.g., Mn = 22,000, Mw/Mn = 1.17) were 178 and 323 °C, respectively. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1629–1637, 2008
Synthesis of highly conductive EDOT copolymer films via oxidative chemical in situ polymerization
Authors: Chen Jui Hung , Dai Chi‐An , Chiu Wen‐Yen 
Published: January 2008

AbstractPoly(3,4‐ethylenedioxythiophene)s (PEDOT) represent a class of conjugated polymers that can be potentially used as an electrode material for flexible organic electronics due to their superior conductivity and transparency. In this study, we demonstrate that the conductivity of a PEDOT containing copolymer film can be further enhanced by the oxidative chemical in situ copolymerization of a liquid film spun coated from monomer mixture (3,4‐ethylenedioxythiophene (EDOT) and 3‐thienyl ethoxybutanesulfonate (TEBS)), oxidant (iron(III) p‐toluenesulfonate (Fe(OTs)3)), weak base (imidazole), and solvent (methanol). We investigated that the effect of the processing parameters such as the molar ratios TEBS/EDOT, IM/EDOT, and Fe(OTs)3/EDOT on the surface morphology, optical property, and the conductivity of the resulting copolymer films. These parameters have been optimized to achieve conductivities for the copolymer films as high as 170 S/cm compared with a conductivity of 30 S/cm for the pure PEDOT film synthesized using the same fabrication method. This conductivity enhancement for the copolymer films was found to be resulted from the fact that the addition of TEBS monomer reduces the copolymerization rate, leading to the formation of much more uniform film surface without defects and copolymers of higher molecular weight which increase the conductivity of the resulting copolymer film. The composition of two monomers in the copolymer film is not related to the variation of conductivity. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1662–1673, 2008
Sonochemical immobilization of silver nanoparticles on porous polypropylene
Authors: Perkas Nina , Shuster Michael , Amirian Galina , Koltypin Yuri , Gedanken Aharon 
Published: January 2008

AbstractSilver nanoparticles were immobilized on the surface of polypropylene (PP) porous beads by an ultrasound‐assisted reduction method. The structure and properties of the silver–PP composite were characterized with XRD, TEM, HRSEM, EDX, XPS, and Raman spectroscopy. Water‐soluble polymers such as PEG, PVA, and PVP were used as stabilizing agents for preventing the agglomeration of the silver nanoparticles. With PVP, a homogeneous distribution of silver nanocrystals, 50 nm in size, on the PP surface was achieved. The mechanism proposed for the silver anchoring to the inert polymer accounts for a localized melting of the PP. The beads of the silver PP composite demonstrated good stability and high antibacterial activity. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1719–1729, 2008
The proliferative effect of estradiol on human prostate stromal cells is mediated through activation of ERK
Authors: Zhang Zhisong , Duan Lei , Du Xiaoling , Ma Hongshun , Park Irwin , Lee Chung , Zhang Ju , Shi Jiandang 
Published: January 2008

AbstractBackgroundEstrogen is involved in the development and progression of benign prostatic hyperplasia (BPH). It can stimulate proliferation of prostate stromal cells (PrSCs). However, the exact mechanism remains unclear.MethodsWe used the primary cultured human PrSCs and a prostate stromal cell line, WPMY‐1, to examine the signaling pathways involved in estrogen‐mediated proliferation of PrSCs. Cells were treated with 17β‐estradiol (E2) or BSA‐E2. Cell proliferation was assessed by the MTT assay and by cell counting. Western blot analysis was used to determine the status of activation of ERK1/2.ResultsResults indicated that both E2 and BSA‐E2 stimulated proliferation of primary PrSCs and WPMY‐1 cells. ERK was rapidly activated by E2 and BSA‐E2. PD98059, which is a selective ERK inhibitor, significantly inhibited estrogen‐induced cell proliferation. PrSCs expressed estrogen receptor α (ERα) and GPR30 but not ERβ. Small hairpin RNA (shRNA) to ERα, but not to GPR30, blocked estrogen‐mediated ERK activation and cell proliferation.ConclusionsThe results indicated that estrogen could activate ERK pathway through the non‐genomic ERα pathway, leading to proliferation of PrSCs. Prostate 68: 508–516, 2008. © 2008 Wiley‐Liss, Inc.
The metabolites citrate, myo‐inositol, and spermine are potential age‐independent markers of prostate cancer in human expressed prostatic secretions
Authors: Serkova Natalie J. , Gamito Eduard J. , Jones Richard H. , O'Donnell Colin , Brown Jaimi L. , Green Spencer , Sullivan Holly , Hedlund Tammy , Crawford E. David 
Published: January 2008

AbstractObjectivesDue to specific physiological functions, prostatic tissues and fluids have unique metabolic profiles. In this study, proton nuclear magnetic resonance spectroscopy (1H‐NMRS) is used to assess potential metabolic markers of prostate cancer (PCa) in human expressed prostatic secretions (EPS).MethodsMetabolic profiles of EPS from 52 men with PCa and from 26 healthy controls were analyzed using quantitative 1H‐NMRS. The metabolites quantified included citrate, spermine, myo‐inositol, lactate, alanine, phosphocholine, glutamine, acetate, and hydroxybutyrate. Logistic regression (LR) was used to model the risk of PCa based on metabolite concentrations while adjusting for age.ResultsThe average age of the EPS donors with PCa was 58.0 ± 7.0 years and 52.2 ± 12.1 for the healthy donors. The median Gleason score for the men with PCa was 7 (range 5–9). The LR models indicated that the absolute concentrations of citrate, myo‐inositol, and spermine were highly predictive of PCa and inversely related to the risk of PCa. The areas under the receiver operating characteristic curves (AUROC) for citrate, myo‐inositol and spermine were 0.89, 0.87, and 0.79, respectively. At 90% sensitivity, these metabolites had specificities of 74%, 51%, and 34%, respectively. The LR analysis indicated that absolute levels of these three metabolites were independent of age.ConclusionsThe results indicate that citrate, myo‐inositol and spermine are potentially important markers of PCa in human EPS. Further, the absolute concentrations of these metabolites in EPS appear to be independent of age, increasing the potential utility of these markers due to elimination of age as a confounding variable. Prostate 68: 620–628, 2008. © 2008 Wiley‐Liss, Inc.
Influence of isomorphous substitution on NO and N2O thermochemistry on Au/ZSM‐5 catalyst
Authors: Sierraalta Anibal , Alejos Paola , Ehrmann Elena 
Published: January 2008

AbstractDensity functional calculations have been carried out to investigate the effects of the Al isomorphic substitution by B and Ga on the geometries, adsorption energies and vibrational frequencies of NO and N2O on a model for Au(I) ion‐exchanged ZSM‐5 catalysts. It is shown for first time, that the adsorption of NO, two NO, and N2O are thermodynamically more favored on Au/[B]ZSM‐5 than on Au/[Al]ZSM‐5 or Au/[Ga]ZSM‐5. The isomorphous substitution in ZSM‐5 affects the electronic properties of Au(I), reducing the band gap HOMO‐LUMO, favoring the NO adsorption. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
Comparison of two test methods for evaluation of forming tool materials
Authors: Hanson Magnus , Gåård Anders , Krakhmalev Pavel , Hogmark Sture , Bergström Jens 
Published: January 2008

AbstractTwo test methods often used to simulate the tribological performance of forming tool materials are compared in this investigation through an evaluation of the friction and wear properties of four tool steels in dry sliding. One test (slider‐on‐flat‐surface (SOFS)) utilises a vertical disc sliding on a horizontal flat test surface, and the other (load scanner (LS) tests) utilises two crossed cylindrical rods. The test conditions were selected as equal as possible for the two tests, and the following conclusions are made.Somewhat unexpectedly, the friction and wear results differed substantially between the two tests. The SOFS test showed a better potential to evaluate wear resistance since one test sample is in continuous contact with the other. The LS test can generate higher contact pressures since the two rods contact each other in an unworn condition throughout the whole test stroke.LS indicate that two hard and smooth tool steels tested against each other generally give low friction and good galling resistance. The two hard couples tested sustained the highest loads without any detectable surface damage. For the same combinations of hard steels, SOFS gave a higher friction due to the wear of the disc. The carbides in the disc material resist wear better than the matrix and will consequently wear the disc by abrasion, which adds to the friction.The above conclusions are drawn from a rather limited examination using only one set of test parameters. In fact, the two tests are both very flexible as to the way they can be used, and they both have advantages and limitations in tribological studies. They should rather be considered complementary than competitive. Copyright © 2008 John Wiley & Sons, Ltd.