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Tang L.-C.,Hangzhou Normal University | Wang X.,Hangzhou Normal University | Gong L.-X.,Hangzhou Normal University | Peng K.,Chongqing Polycomp International Corporation | And 5 more authors.
Composites Science and Technology | Year: 2014

In this work, we investigate the creep and recovery behaviours of polystyrene (PS) composites filled with two-dimensional chemically reduced graphene oxide (CRGO) sheets. Incorporation of CRGO into PS polymer is found to significantly improve the creep resistance and recovery properties. The results are compared with the creep and recovery of the corresponding composites with carbon black (CB) and carbon nanotube (CNT) nano-additives, and it is observed that both the CB/PS and CNT/PS systems present worse efficiencies in reducing the creep and unrecovered response. The CRGO sheets with corrugated structures possess higher specific surface area and display better dispersion in the PS matrix compared to the CB or CNT nano-additives, which should produce strong sheet/matrix interfacial interaction to restrict the mobility of polymer chains. The formation mechanisms are further interpreted based on the analysis from the dynamic mechanical properties and thermo-gravimetric results. © 2013 Elsevier Ltd. Source


Tang L.-C.,Hangzhou Normal University | Wan Y.-J.,Hangzhou Normal University | Peng K.,Chongqing Polycomp International Corporation | Pei Y.-B.,Hangzhou Normal University | And 5 more authors.
Composites Part A: Applied Science and Manufacturing | Year: 2012

The attainment of both high toughness and superior electrical conductivity of epoxy composites is a crucial requirement in some engineering applications. Herein, we developed a strategy to improve these performances of epoxy by combining the multi-wall carbon nanotubes (MWCNTs) and spherical particles. Two different types of spherical particles i.e. soft submicron-rubber and rigid nano-silica particles were chosen to modify the epoxy/MWCNT composites. Compared with the binary composites with single-phase particles, the ternary composites with MWCNTs and spherical particles offer a good balance in glass transition temperature, electrical conductivity, stiffness and strength, as well as fracture toughness, exhibiting capacities in tailoring the electrical and mechanical properties of epoxy composites. Based on the fracture surface analysis, the complicated interactions between multiscale particles and the relative toughening mechanisms were evaluated to explain the enhancement in fracture toughness of the ternary composites. © 2012 Elsevier Ltd. Source


Wang X.,Hangzhou Normal University | Gong L.-X.,Hangzhou Normal University | Tang L.-C.,Hangzhou Normal University | Peng K.,Chongqing Polycomp International Corporation | And 4 more authors.
Composites Part A: Applied Science and Manufacturing | Year: 2014

Resistance to time-dependent plastic deformation of polymer composite materials is a crucial requirement in their application for long-term durability and reliability. Herein, creep and recovery behaviors of polystyrene (PS) composites filled with various loadings of chemically reduced graphene oxide (CRGO) were investigated at different environment temperatures. As expected, incorporation of CRGO into PS polymer increases the thermal stability, glass transition temperature and elastic modulus, although the tensile strength of the composite has a slight decrease. It was found that the creep deformation and strain rate of PS polymer reduce with decreasing temperature and with increasing loading of CRGO. A significant improvement in the recovered strain of PS was also obtained after the presence of CRGO. Based on the analytical modelings (Burger's model and Weibull distribution function) and experimental results, the role of CRGO on improving the creep and recovery performance of thermoplastics was proposed and discussed. © 2014 Elsevier Ltd. All rights reserved. Source


Deng H.-L.,Northwestern Polytechnical University | Deng H.-L.,Xian Aerospace Composites Research Institute | Li K.-Z.,Northwestern Polytechnical University | Li H.-J.,Northwestern Polytechnical University | And 3 more authors.
Xinxing Tan Cailiao/New Carbon Materials | Year: 2013

Two-dimensional needle-punched carbon fiber felts were densified using film boiling chemical vapor infiltration with heaters above and below the felt and using xylene pyrolysis at 900-1200°C. The pyrocarbon deposition rate was calculated from the mass gain of the composites. The density of the composites and the thickness of the pyrocarbon were measured by the Archimedes method and polarized light microscopy, respectively. The effects of deposition temperature and heater configuration on the densification behavior of the composites were investigated. Results showed that C/C composites with a density of 1.70-1.73 g/cm3 were produced after 30-35 h densification. The deposition front thickness and initial deposition rate of the pyrocarbon increased with deposition temperature from 900-1000°C to 1100-1200°C. However, the difficulty of precursor transfer increased at higher deposition temperatures due to a more rapid densification at the preform edge, leading to a density decrease of the composites from 1.72-1.73 g/cm3 at 900-1000°C and 1000-1100°C to 1.70 g/cm3 at 1100-1200°C if upper heater was not used. Moreover, the densification uniformity of the composites decreased, and their density gradients along both the axial and radial directions were larger than 0.04 g/cm3. When the upper heater with many holes along its axial direction was used, the thickness of the deposition front decreased whereas the mass transfer efficiency of precursor into the preform increased, which had the advantage of improving the density and uniformity of the composites for the higher deposition temperature of 1100-1200°C. Source


Patent
Chongqing Polycomp International Corporation | Date: 2015-05-28

A low dielectric constant glass fiber, in mass percentage, includes 50%60% of SiO

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