Enhancing the Electrical Conductivity and Strength of PET by Single-Wall Carbon Nanotube Film Coating.

Single-wall carbon nanotubes (SWCNTs) with excellent physicochemical properties are considered a promising candidate for the electrical and mechanical reinforcements of polymers. However, the poor dispersion of SWCNTs in plastics seriously limits their application and their achieved performance enhancement. Here, we coat a freestanding, highly conductive SWCNT film onto the surface of a polyethylene terephthalate (PET) film by a hot-pressing method. Due to the uniform SWCNT network structure and strong interfacial interaction, the SWCNT/PET hybrid film showed notably enhanced electrical and mechanical properties even though with a very low SWCNT weight fraction of 0.066%. The surface square resistance of the SWCNT/PET film decreased to 120-140 Ω/□ from 1016 Ω. In addition, Young's modulus and tensile strength of the SWCNT/PET film reached 4.6 GPa and 148 MPa, which are 31.3 and 24.4%, respectively, higher than the pure PET film. The SWCNT/PET film shows excellent mechanical durability and thermal stability, demonstrating its potential use as an antistatic material.

[Spectroscopic characterization and properties of Mg2B2O5w/AZ91D magnesium composites].

Magnesium borate whisker (Mg2B2O5 w) reinforced Mg matrix composite was fabricated by vacuum-gas pressure infiltration process. The Mg2B2O5 w preforms forming process was determined. The Mg2B2O5 whiskers were fabricated into a preform by wet forming method without any binder. The Vacuum-Gas Pressure Infiltration process and parameters are also developed. The micrographs revealed reasonably uniform distribution and random orientation of the whiskers in the as-cast Mg2B2O5 w/AZ91D composite and the composites were without pores defect. The phases were analyzed by XRD patterns for the as-received whiskers, the whiskers sintered at 1 000 degrees C for 3 h and the as-cast composite, respectively. Then, the microstructure evolution of the composite was investigated when the composite was heat-treated. Meanwhile, the relationships between microstructure and micro-hardness of the alloy heat-treated were also studied. The heat-treatment condition were solution at 415 degrees C for 8 and 24 h, respectively, aging treatment at 200 degrees C for 8, 12, 16, 20 and 24 h, respectively and solution at 415 degrees C for 8 or 24 h and subsequent aging treated for 8, 12, 16, 20, 24 h, respectively. The phases were analyzed by XRD patterns for the composites after different heat treated process. The results of XRD patterns were shown to be in good agreement with the microstructures evolution of the composites. The results showed that the micro-hardness of the solution treated composites is decreased due to resolution of eutectic phase, whereas the micro-hardness of the aged composites was increased gradually and the peak hardness is reached to 201 HV in the composite aged for 16 hours. Solution treatment at 415 degrees C for 24 h, the beta-Mg17, Al12 phase is dissolved in the alpha-Mg phase to form oversaturated solid-solution in the composite and then the diffusive beta phase precipitates after subsequent aging treatment at 200 degrees C for 8 h; hence the micro-hardness of the composite was increased 30%. However, as the aging time increased to 24 h, the hardness of the composite was reduced to 183 HV because the beta-Mg17 Al12 phase precipitate changed from continuous fine platelets to discontinuous coarse platelets. It was concluded that the process of solution at 415 degrees C for 24 h and subsequent aging treatment at 200 degrees C for 8 h was the best process for the composite.