Materials Science and Engineering Technology

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Authors: Shi Hui Chen, Jun Gang Gao, Hong Zhe Han, Chao Wang
Abstract: In order to modify the properties of the epoxy composites, an alkali catalyzed biphenyldiol formaldehyde resin (BPFR) was synthesized and used to cure epoxy resin (ER). γ-Glycidoxypropyl trimethoxysilane (KH-560) was used as a reinforcer of the composites. Laminates of the BPFR/ER fiberglass reinforced composites with different (KH-560) contents were prepared. The influence of the KH-560 content on the glass transition temperature (Tg) and thermal degradation properties of the composites was researched by dynamic mechanical analyzer (DMA) and thermogravimetric analysis (TG). The mechanical, electrical properties of the composites were determined. The results showed that the interfacial bonding strength between resin matrix and fiberglass can be efficiently improved with the presence of KH-560. When the ratio of BPFR and ER is 3 : 7, the content of KH-560 is 5 ~7 wt%, the impact resistance of the fiberglass reinforced composites is 61.35~78.59 kJ/m2, the tensile resistance is 150.37~162.54 MPa, which are all 30 % higher than that of no added; The dielectric constant ε and dielectric loss tanδ of the composites is between 0.50~0.68 and between 0.008~0.01, respectively.
Authors: Chun Yuan Liu, Wei In Lin, Jenshi B. Wang
Abstract: A new method is proposed to improve blend compatability through inclusion complexation. The host polymer and the guest polymer are synthesized respectively and blended to form a film. The transparency of blend film increases and, at some composition, a third Tg is obsereved, indicating the inclusion complex between these two polymers
Authors: Run Miao Yang, Yu Hai Liu, Guan Xiu Dong, De Jian Zhao
Abstract: Polyacrylamide (PAM) was chemically anchored to the surface of multi-walled carbon nanotubes (MWCNTs) by atom transfer radical polymerization (ATRP) of acrylamide (AM). It started from the functional groups such as –COOH on the sidewall of MWCNTs, which derived from the oxidation of carbon nanotubes. FT-IR and 1H NMR results shown that the multi-walled carbon nanotubes grafted PAM (MWCNT-g-PAM) have been successfully carried out. The MWCNT-g-PAM showed different relative weight loss kinetics with PAM determined by thermal gravimetric analysis (TGA). The transmission electron microscopy (TEM) shown that the PAM grafted polymer was wrapped on the surface of carbon nanotubes.
Authors: Xin Li, Yu Xiang Ou
Abstract: Polypropylene (PP) and ethylene vinyl acetate copolymer (EVA) were treated with intumescent flame retardants containing caged bicyclic phosphates. The behavior of thermal degradation of the flame-retarded PP and EVA were studied by TG, DSC, and the FTIR spectra of PP’s residues at different temperature were recorded. In addition, the possible thermal degradation and char formation mechanisms were analyzed and discussed.
Authors: Yi Si
Abstract: The effect of different concentrations of Pr on the microstructure and tensile properties of cast Al-18 wt.%Mg2Si in situ metal matrix composite was investigated. The results show that the addition of proper amount of Pr has significant modification effect on primary Mg2Si in the Al-18 wt.% Mg2Si composite. With the increase of Pr content from 0.1 to 0.7%, the morphology of primary Mg2Si is changed from irregular or dendritic to polyhedral shape, and its average particle size is significantly decreased from 65 to 17 μm. When the Pr content exceeds 1.0%, the primary Mg2Si become coarse again. Tensile tests reveal that the Pr addition improves the tensile strength and ductility of the material. Comparing with those of unmodified composite, the ultimate tensile strength and percentage elongation with 0.7% Pr are increased by 36.5% and 161.6%, respectively.
Authors: Wei Xing Deng, Yuan Wei Zhong, Jie Qin, Xue Bing Huang, Jin Wen Peng
Abstract: A new epoxy resin based on dichlorosilane and 9,9-bis (4-hydroxyphenyl) fluorene was synthesized to produce a highly heat-resistant network. The chemical structure was characterized with FTIR spectroscopy and 1H-NMR. 4-4′-Diaminodiphenylsulfone (DDS) was used as the curing agent. The curing kinetics of different epoxy/DDS systems were investigated using non-isothermal differential scanning calorimetry (DSC). The results showed that the values of activation energy (E) were affected by the chemical structure of epoxy resin, and BPEBF exhibited lower curing reactivity towards DDS compared to E-51.
Authors: Long Hui Zheng, Bao Ling Chen, Hai Bin Huang, Qin Hui Chen, Jin Huo Lin
Abstract: The core @ shell composite particles of polystyrene @ urushiol-titanium chelate polymer (PS @ UTi) was prepared through in-situ reaction between sulfonated polystyrene microspheres coated tetrabutyl titanate and urushiol. The resultant PS @ UTi was characterized by scanning electron microscope and transmission electron microscope. Results indicated that the PS @ UTi with the excellent properties of raw lacquer was synthesized. The shell thickness of UTi coated on PS was tunable by changing the sulfonation time.
Authors: Qin Hui Chen, Jin Huo Lin
Abstract: The polypropylene-graft-cardanol (CAPP) was prepared by reactive extrusion with polypropylene (PP) and natural renewable cardanol which could improve the inherent defects of PP such as chemical inertness and hydrophobicity. Moreover, the cardanol grafted onto PP could resolve the degradation of PP during the process of reactive extrusion. In this paper, CAPP was prepared in the presence of three different kinds initiator. The compatibilization and the anti-aging performance of cardanol grafted onto PP were studied. Results showed that the initiator dicumyl peroxide (DCP) exhibited the optimum initiated efficiency. Cardanol grafted onto PP was benificial for the composite of bamboo powder and PP.The initiator of DCP caused the degradation of PP chains during the aging processing. After aged for 24 h, the yield strength decreased from 28 MPa to 15 MPa and the elongation at break reduced by 795 %. The CAPP possessed outstanding anti-aging performance owing to the cross-linking and entanglement of the side chains of cardanol grafted onto PP. The yield strength, tensile strength and the elongation at break of CAPP-DCP changed lightly even when it was in long-term irradiation for 480 h.
Authors: Xiang Hong Kong, Zhi Jin Wang
Abstract: Experiment and Finite element analysis were used to study the strengths of composite laminates with and without holes. Finite element progressive damage analysis with Tsai-Wu criteria was applied to calculate the compressive residual strength of composite laminate. Abaqus and its user subroutine USDFLD were used for the finite element analysis. Tsai-Wu criteria as the failure criteria was realized in USDFLD as a Fortran program segment, and the stiffness degradation for the damaged elements was also realized by USDFLD. Analytic results gotten by progressive damage method were very close to the experimental results.

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