bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermal stability and ablation properties study of aluminum silicate ceramic fiber and acicular wollastonite filled silicone rubber composite
Authors: Yu Lin , Zhou Shengtai , Zou Huawei , Liang Mei 
Published: August 2013

ABSTRACTThe thermal stability and ablation properties of silicone rubber filled with silica (SiO2), aluminum silicate ceramic fiber (ASF), and acicular wollastonite (AW) were studied in this article. The morphology, composition, and ablation properties of the composite were analyzed after oxyacetylene torch tests. There were three different ceramic layers found in the ablated composite. In the porous ceramic layer, the rubber was decomposed, producing trimers, tetramers, and SiO2. ASF and part of AW still remained and formed a dense layer. The SiO2/SiC filaments in the ceramic layer reduced the permeability of oxygen, improving the ablation properties of the composites. The resultant ceramic layer was the densest, which acted as effective oxygen and heat barriers, and the achieved line ablation rate of the silicone composite were optimum at the proportion of 20 phr/40 phr (ASF/AW). Thermogravimetric analysis (TGA) confirmed that thermal stability of the composites was enhanced by the incorporation of ASF and AW. The formation of the ceramic layer was considered to be responsible for the enhancement of thermal stability and ablation properties. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39700.
Pulverized polyurethane foam particles reinforced rigid polyurethane foam and phenolic foam
Authors: Yang Chao , Zhuang Zhe‐Hui , Yang Zhen‐Guo 
Published: August 2013

ABSTRACTPolyurethane consumption has been increasing in recent years, raising concerns about how to deal with the polymer waste. Post‐consumer rigid polyurethane foams or polyurethane foam scraps (PPU) ground into particles were utilized to strengthen mechanical properties of rigid polyurethane foam (PUF) and phenolic foam (PF). Viscosity of prepolymer with PUF was measured and PPU was well dispersed in prepolymer, as observed by optical microscope. Microstructures and morphologies of the reinforced foam were examined with scanning electron microscope (SEM) while cell diameter and density were measured by Scion Image software. Universal testing machine was employed to optimize compressive properties at various weight ratios of PPU. Both PUF and PF with 5 wt % PPU, respectively, exhibited considerable improvement in mechanical properties especially compressive property. The compressive modulus of PUF with 5 wt % PPU was 12.07 MPa, almost 20% higher than pure PUF while compressive strength of PF with 5 wt % PPU reached 0.48 MPa. The thermal stability of the reinforced foam was tested by thermal gravity analysis (TGA) and the result shows no obvious impact with PPU. The decomposition temperatures of PUF with PPU and PF with PPU were 280°C, because PPU has relatively weak thermal stability. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39734.
Electrosynthesis and characterization of an electrochromic material from poly(1,6‐bis(2‐thienyl)pyrene) and its application in electrochromic device
Authors: Cheng Xinfeng , Fu Yunzhi , Zhao Jinsheng , Zhang Yucang 
Published: August 2013

ABSTRACTElectrochemical polymerization of 1,6‐bis(2‐thienyl)pyrene (BTP) could be achieved in acetonitrile/dichloromethane (ACN/DCM) (1:1, by volume) solution containing sodium perchlorate (NaClO4) as a supporting electrolyte. The resulting polymer poly(1,6‐bis(2‐thienyl)pyrene) (PBTP) were characterized by cyclic voltammetry, UV–vis spectroscopy, and scanning electron microscopy. The resulting polymeric film has distinct electrochromic properties and exhibits three different colors under various potentials. Moreover, the PBTP film showed reasonable optical contrast (DT %) at 700 nm is found to be 29% and satisfactory response time is measured as 1.3 s. An electrochromic device (ECD) based on PBTP and poly(3,4‐ethylenedioxythiophene) was also constructed and characterized. This ECD has these qualities: quick switching time, reasonable contrast, and good optical memories and redox stability. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39770.
Mechanical and damping properties of epoxy/liquid rubber intercalating organic montmorillonite integration nanocomposites
Authors: Mao Duming , Zou Huawei , Liang Mei , Zhou Shengtai , Chen Yang 
Published: August 2013

ABSTRACTTwo different kinds of micro‐nanoconstrained damping structure units (M‐NCDSUs) were prepared by carboxyl‐terminated butadiene acrylonitrile copolymer and epoxy‐terminated butadiene acrylonitrile copolymer liquid rubbers intercalating organic montmorillonite, respectively. The prepared M‐NCDSUs were then blended with epoxy resin to obtain damping structure integration nanocomposites. The X‐ray diffraction and transmission electron microscope measurements applied for the obtained samples confirmed the good formation of M‐NCDSUs in the epoxy network. The tensile strength decreased slightly with the addition of M‐NCDSUs, whereas the damping properties measured by dynamic mechanical analysis showed a remarkable increase. Besides, the cured epoxy resin exhibited a two‐phase morphology where the spherical rubber phase dispersed uniformly in the epoxy matrix. The nanocomposites containing M‐NCDSUs showed superior comprehensive properties compared with that without the functional units. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39797.
Acetophenone‐assisted main‐chain photocrosslinking of poly(ethylene terephthalate)
Authors: Yun Deuk‐Won , Jang Jinho 
Published: August 2013

ABSTRACTMaximum gel fraction of 99.1% was obtained under continuous UV irradiation of a UV energy of 200 J cm−2 on poly(ethylene terephthalate) (PET) containing only in presence of 2.9%(w/w) acetophenone (AP). The fragmented AP radicals abstract the hydrogen atoms of methylene units in PET, producing secondary methine radicals which couples to main‐chain crosslinks. The crystal structure of the crosslinked PET became disordered remarkably. The glass transition temperature disappeared and the peak thermal decomposition temperature was significantly retarded as much as 85°C. The crosslinking density and molecular weight between crosslinks reaches up to 0.129 mol g−1 and 7.7 g mol−1, respectively. Also tensile modulus and strength increased by 200 and 72% compared with those of the pristine PET respectively, resulting in more toughened PET. The solid‐state photocrosslinking may extend high‐temperature applications of PET with enhanced thermal and mechanical properties. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39802.
Influence of the coupling agent on the mechanical properties of SiCf/poly(phenylene benzobisoxazole) composites
Authors: Wang Li , Luo Fa , Zhou Wancheng , Zhu Dongmei 
Published: August 2013

ABSTRACTPoly(phenylene benzobisoxazole) (PBO) was first used as matrix to fabricate the two‐dimensional SiCf/PBO composites by a lamination method. Different amounts of coupling agent were introduced to improve the bonding between silicon carbide (SiC) fibers and the PBO matrix during the fabrication of the SiCf/PBO composites. The surface structure and composition of the as‐received PBO and PBO treated with the coupling agent were analyzed, and the morphology and flexural strength of the composites were characterized. The Fourier transform infrared analysis indicated that the hydroxyl groups from the coupling agent were successfully introduced to PBO. The flexural strength of the composites increased at first with increasing content of the coupling agent but decreased with excessive addition of the coupling agent. The flexural strength of the composites was improved from 15 to 89 MPa. The test results suggested that the interaction between the SiC fiber and the treated PBO with the coupling agent was intensified. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39805.
Cyclic and monotonic testing of free and constrained recovery properties of a chemically crosslinked acrylate
Authors: Arrieta J. Sebastian , Diani Julie , Gilormini Pierre 
Published: August 2013

ABSTRACTA chemically crosslinked acrylate network was submitted to various thermomechanical strain and stress recoveries whilechanging the experimental parameters in order to better define the benefits and the limits of using chemically crosslinked polymers for multicycle applications or applications under external constraints. The results showed that the free recoveries and the constrained recoveries remained the same at the first cycle and during the next ones. It was also shown that the low stress usually generated by a crosslinked network when submitted to a constrained recovery can be significantly increased by choosing suitable experimental conditions. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39813.
Flame retardancy and thermal properties of carboxyl‐containing polysiloxane derivatives in polycarbonate
Authors: Song Rongjun , Chang Liyan , Li Bin 
Published: August 2013

ABSTRACTCarboxyl‐containing polysiloxane (LCCP) has been successfully applied in the flame retardancy of polycarbonate (PC). The LCCP was synthesized by hydrosilylation and condensation reaction. The presence of carboxyl groups has been demonstrated to be crucial to provide high flame retardant effectiveness. The flame retardancy of LCCP–PC composites is investigated by limiting oxygen index (LOI), vertical burning tests (UL‐94). At the mole ratio of diethoxymethyl (1‐propionyloxy) silane/diethoxydimethylsilane = 8/100 in LCCP(3), the best flame retardant performance of LCCP‐PC composites was obtained. The LOI value of the composites is 38.5 and the UL‐94 rating reaches V‐0 when the content of LCCP(3) is as low as 0.5 wt %. Evolution of the thermal behaviors of the composites tested by thermogravimetric analysis shows that addition of LCCP(3) in PC can reduce the degradation speed of PC and induce a reduction of the initiated decomposition temperature of PC. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014, 131, 39814.
Thermoplastic elastomers derived from bio‐based monomers
Authors: Ghassemi Hossein , Schiraldi David A. 
Published: August 2013

ABSTRACTSeries of copolyesters based on poly(propylene succinate) (PPS) and poly(butylene succinate) (PBS), which can be produced from biological feedstock, and postconsumer poly(ethylene terephthalate) (PET) were synthesized with the aim of developing sustainable materials, which combine the mechanical properties of high performance elastomers with those of flexible plastics. The aliphatic polyesters were synthesized by the catalyzed two‐step transesterification reaction of dimethyl succinate, 1,3‐propanediol, and 1,4‐butanediol followed by melt reaction with PET in bulk. The content of PET segments in the polymer chains was varied from about 10 to 100 wt % per 100 wt % PPS or PBS. The effect of the introduction of the PET segments on the structure, thermal, physical, and mechanical properties was investigated. The composition and structure of these aliphatic/aromatic copolyesters were determined by NMR spectroscopy. The thermal properties were investigated using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The level of crystallinity was studied by means of DSC and wide‐angle X‐ray scattering. A depression of melting temperature and a reduction of crystallinity of copolyesters with increasing content of PET segments were observed. Consequently, the tensile modulus and strength of copolyesters decreased, and the elongation at break increased with PET content in the range of 10−50 wt %. Thus, depending on PET content, the properties of copolyesters can be tuned ranging from semicrystalline polymers possessing good tensile modulus (380 MPa) and strength (24 MPa) to nearly amorphous polymer of high elongation (∼800%), and therefore they may find applications in thermoplastics as well as elastomers or impact modifiers. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39815.
Chemical modification of bisphenol a polycarbonate by reactive blending with ethylene carbonate
Authors: Colonna Martino , Berti Corrado , Fiorini Maurizio 
Published: August 2013

ABSTRACTA new method for the insertion of aliphatic moieties into bisphenol A (BPA) polycarbonate (PC) by reactive blending with ethylene carbonate (ETC) has been developed. By this route, new polymeric materials with modified thermal and rheological properties have been synthesized; the structure of the poly(ether‐co‐carbonate)s prepared can be controlled using different ETC/PC molar ratios. Using model compounds and selective degradation reactions, the different chemical structures of the aliphatic units inserted into PC backbone were identified. ETC/PC molar ratios below 1 afforded both aliphatic–aromatic carbonate and ether groups, while higher ETC/PC molar ratios afforded aliphatic–aromatic ether and aliphatic–aliphatic carbonate groups. The co‐polymers prepared by the new process were clear without discoloration or opacity. The thermal analyses of the co‐polymers showed that, by the insertion of aliphatic moieties, it is possible to modulate the glass transition temperature (Tg) in a 30°C range. A decreased melt viscosity of the co‐polymers was also observed and therefore an improved processability should be expected with respect to standard PC. The reaction with aliphatic carbonates can be also considered as a promising chemical recycling process for PC scraps, through the synthesis of monomers such as bis(hydroxyethyl)ether of BPA. This monomer has already been used for the preparation of co‐polyesters of terephthalic acid with high Tg and thermal stability. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014, 131, 39820.
Viscoelastic properties and structure of poly(acrylonitrile‐co‐methacrylic acid) polymer solutions for gel spinning at long aging times
Authors: Brown Tracy R. , Choudhury Rudra P. , Meree Caitlin E. , Beckham Haskell W. , Kumar Satish , Shofner Meisha L. 
Published: August 2013

ABSTRACTThe objective of the research is to obtain a more complete understanding of how aging affects the viscoelastic properties of polymer solutions to be used as starting materials for gel spinning of polymer fibers. Specifically, poly(acrylonitrile‐co‐methacrylic acid) solutions were prepared and characterized using rheological measurements and nuclear magnetic resonance spectroscopy. The results indicate that elastic character increased with increasing polymer concentration and that gelation of these solutions continued up to aging times of several weeks. Additionally, comparing the results from the two characterization methods show that while gelation continues to occur, the viscoelastic properties decrease after a critical time point suggesting that a chemical change occurs in the solutions at long times. However, these changes impact the solution dynamics minimally as the effective network properties were similar at the aging times studied here, but considerations for long‐term storage of polymer solutions for gel spinning are warranted. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39821.
Frontal polymerization of superabsorbent nanocomposites based on montmorillonite and polyacrylic acid with enhanced soil properties
Authors: Zhang Ruobing , Qiu Zhaoxia , Qiu Haixia , Zhang Xionghui 
Published: August 2013

ABSTRACTPolyacrylic acid/montmorillonite(MMT)/carboxymethylcellulose (CMC) superabsorbent nanocomposites were prepared by frontal polymerization (FP), an economic method characterized by low‐energy consumption and short‐reaction time. They were characterized by Fourier transform infrared spectroscopy, X‐ray diffraction, transmission electron microscopy, and scanning electron microscopy. The effects of reaction parameters on the front propagation and the water absorbency of the nanocomposites were investigated. Furthermore, the effects of the obtained products on soil water holding capacity and soil water stable macro‐aggregates were studied. Compared with the control soil, soil mixed with the nanocomposites showed a significant increase (by 52.4%) in field water holding capacity. The incorporation small amounts of MMT effectively promoted the formation of soil water stable macro‐aggregates, which increased by 76% as the addition of the MMT increased to 4 wt %. The samples obtained by FP showed much better performance in the formation of soil water stable macro‐aggregates, salt resistance, and thermal stability than those obtained by conventional batch polymerization. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39825.
Effect of K0.5Na0.5NbO3 filling particles on the charge carrier trap distribution of polyimide films
Authors: Lin Jiaqi , Xie Zhibin , Yang Wenlong , Zhang Panpan , Liu Ying , Lin Hui , Li Xiaokang 
Published: August 2013

ABSTRACTPolyimide (PI) films filled with K0.5Na0.5NbO3 (KNN50) particles at different weight 0, 5, 10, and 15 wt % had been prepared by in‐situ dispersion polymerization process. The thermally stimulated current (TSDC) method was used to investigate the charge carrier trap levels and their distribution of the composite films. The TSDC spectra show that pure film has
‐peaks and
‐peak, but the composite films only have
‐peaks and an extraordinary peak at high temperature region. The trap parameters were calculated by an approximate model, and the results indicate that charge released of the shallow traps show a nonlinear behavior. The trap energies decrease from 0.879–0.968 eV to 0.549–0.839 eV with the increase of the KNN50 content. The surface and interface between KNN50 and PI matrix was considered to the variation of the trap levels. The extraordinary peak of the composite films was correlated with the phase transition of the KNN50 particles. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39828.
Improvement in impact strength of modified cardanol‐bonded cellulose thermoplastic resin by using olefin resins
Authors: Kiuchi Yukihiro , Soyama Makoto , Iji Masatoshi , Tanaka Shukichi , Toyama Kiyohiko 
Published: August 2013

ABSTRACTImpact strength of a modified cardanol‐bonded cellulose thermoplastic resin was greatly improved by using a small amount of olefin resins. As we showed, this thermoplastic resin (3‐pentadecylphenoxy acetic acid (PAA)‐bonded cellulose diacetate (CDA): PAA‐bonded CDA) exhibited high practical properties such as bending strength, heat resistance, and water resistance. However, its impact strength was insufficient for use in durable products. We improved the impact strength of PAA‐bonded CDA by adding hydrophobic olefin resins, such as polyethylene or polypropylene, while maintaining good bending strength and breaking strain. Furthermore, the application of olefin resins also increased water resistance and fluidity. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39829.
Cure monitoring of epoxy films by heatable in situ FTIR analysis: correlation to composite parts
Authors: Braun Ulrike , Brademann‐Jock Kerstin , Stark Wolfgang 
Published: August 2013

ABSTRACTThe curing mechanism of an epoxy film containing dicyandiamide (DICY) and an epoxy formulation based on diglycidyl ether of Bisphenol A (DGEBA) polymer was studied as a function of various temperature programs. The investigation was performed in situ, using a thin film of the epoxy mixture on a silicon wafer substrate in a heatable transmission tool of a FTIR spectrometer. Based on these model‐curing experiments, a major curing mechanism was proposed, taking into account the appearance, the decrease, and the development of characteristic bands at various temperatures. The conclusions of the model curing were correlated to FTIR measurements on a real, 50‐mm‐thick glass fiber reinforced component composite part from a technical process. It could be shown that characteristic bands that develop at curing temperatures above 150°C appear especially in the center of the thick sample. From the chemical or molecular point of view, this demonstrates the established technician's understanding that temperature control inside a large‐scale fiber composite of, for example, aircraft, wind‐turbine, automotive applications component is of major importance. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39832.
Effects of magnetic nanoparticle‐incorporated human bone marrow–derived mesenchymal stem cells exposed to pulsed electromagnetic fields on injured rat spinal cord
Authors: Cho Hyunjin , Choi Yun‐Kyong , Lee Dong Heon , Park Hee Jung , Seo Young‐Kwon , Jung Hyun , Kim Soo‐Chan , Kim Sung‐Min , Park Jung‐Keug 
Published: August 2013

AbstractTransplanting mesenchymal stem cells into injured lesions is currently under study as a therapeutic approach for spinal cord injury. In this study, the effects of a pulsed electromagnetic field (PEMF) on injured rat spinal cord were investigated in magnetic nanoparticle (MNP)‐incorporated human bone marrow–derived mesenchymal stem cells (hBM‐MSCs). A histological analysis revealed significant differences in MNP‐incorporated cell distribution near the injured site under the PEMF in comparison with that in the control group. We confirmed that MNP‐incorporated cells were widely distributed in the lesions under PEMF. The results suggest that MNP‐incorporated hBM‐MSCs were guided by the PEMF near the injured site, and that PEMF exposure for 8 H per day over 4 weeks promoted behavioral recovery in spinal cord injured rats. The results show that rats with MNP‐incorporated hBM‐MSCs under a PEMF were more effective on the Basso, Beattie, and Bresnahan behavioral test and suggest that the PEMF enhanced the action of transplanted cells for recovery of the injured lesion.
Changes in clearance, volume and bioavailability of immunosuppressants when given with HAART in HIV‐1 infected liver and kidney transplant recipients
Authors: Frassetto Lynda , Floren Leslie , Barin Burc , Browne Matthew , Wolfe Alan , Roland Michelle , Stock Peter , Carlson Laurie , Christians Uwe , Benet Leslie 
Published: August 2013

ABSTRACTSolid organ transplantation in human immunodeficiency virus 1 (HIV)‐infected individuals requiring the concomitant use of immunosuppressants (IS) [e.g. cyclosporine (CsA) or tacrolimus (TAC)] and antiretrovirals (ARVs) [e.g. protease inhibitors (PIs) and/or non‐nucleoside reverse transcriptase inhibitors (NNRTIs)] is complicated by significant drug interactions. This paper describes the pharmacokinetics of CsA and TAC in 52 patients on both IS and NNRTIs, PIs or combined NNRTIs + PIs, in studies conducted at 2 weeks, 3, 6, 12 and 24 months after transplantation. Cyclosporine and TAC blood concentrations were measured by LC/MS/MS. This multisubject, varied ARV–IS drug combination, longitudinal observational patient study provided a unique opportunity to examine the effect of different ARV drugs on IS pharmacokinetics (PK) by comparing the ratios of parameters over time and between PK parameters. Subjects taking concomitant PIs exhibited increases in CsA and TAC exposure (AUC/dose) due to the increased apparent oral bioavailability and decreased apparent oral clearance. Those subjects taking CsA and concomitant efavirenz (EFV) showed time dependent increases in exposure due to ~30% increases in the apparent oral bioavailability over time as well as a decreased apparent oral clearance, while subjects on TAC and EFV showed time‐dependent changes in all PK parameters. The increased bioavailability was not observed in patients on CsA and nevirapine (NVP). These differences between IS drugs and the changes in PK parameters are not easily predicted, illustrating the importance of continued therapeutic drug monitoring in patients on these complex medication regimens. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.