No abstract

In this work, a simple and novel method was applied to prepare polymer composites by taking the advantage of melt flow shear force driving orientation of the fillers. By using this method, hexagonal boron nitride/polyethylene (hBN/PE) and hexagonal boron nitride/carbon fibers/polyethylene (hBN/CF/PE) composites were fabricated to be possessed of high thermal conductivity and mechanical properties. A high thermal conductivity of 3.11 W/mK was realized in the composite containing 35 wt% hBN and 5 wt% CF, which was over 1,200% higher than that of unfilled PE matrix. Under this component, the compressive strength and modulus of hBN/CF/PE composite were determined to be 30.1 and 870.9 MPa, respectively, which were far higher than that of unfilled PE accordingly. The bending performance was also somewhat enhanced. Meanwhile, the bulk resistivity of the composite material reached 2.55 × 1011 Ω·cm, which was basically the same as that of pure PE. The novel composites with high thermal conductivity, excellent mechanical properties, and controllable electrical insulation could be a potential thermal management material for electrical and electronics industries.

Polyetheretherketone (PEEK) composites reinforced by short carbon fibers (SCF) and potassium titanate whiskers (PTW) were prepared using twin-screw extrusion compounding and injection molding. The tribological properties of hybrid composites were investigated in dry sliding condition against steel. The effects of filler contents on the wear behavior were studied. It was found that the hybrid composite showed an excellent tribological property in dry sliding condition. Applied load had great effect on the tribological behavior of the composites. In most cases, the friction coefficient of the composite decreased with the load rising. The composites with higher CF contents showed outstanding tribological performances at low load but could worsen the wear behavior at high load. Because of the positive effect of PTW, high PTW loading composites presented low wear rate at low load. At high loads, the composites with lower PTW contents had better wear resistance. The scanning electron microscopy (SEM) observation revealed that abrasion wear was attributed to the lower wear resistance of the high PTW content composite at high load. V C 2011 Wiley Periodicals, Inc. J Appl Polym Sci 123: [740][741][742][743][744][745][746][747][748] 2012

Novel polymer blends of polyamide and linear low-density polyethylene with maleated polyethylene as compatibilizers were prepared in a modular intermeshing corotating twin-screw extruder. Polymer blends with different contents of polyamide in polyethylene matrix were obtained. The mechanical properties were studied in terms of the tensile strength and elongation-tobreak. The shape-memory properties of the blended materials were characterized using three-point bending test in a temperature-controlled chamber. The results show that the incorporation of maleated polyethylene has a strong effect on the tensile properties and the morphology of the blends. The shape-memory effect of blended materials is affected by polyamide weight fraction, and 60 wt % polyethylene, 20 wt % polyamide, and 20% maleated polyethylene have an acceptable performance.