No abstract

No abstract

No abstract

Polypropylene (PP) nanocomposites reinforced with different types of graphene nanoplatelets (GNPs) and their hybrid systems are prepared via melt extrusion. On the basis of experimental analysis and simulation, the factors of thermal property of the PP/GNPs nanocomposites, including GNPs size, weight filling ratio and proportion of various sizes, are systematically investigated. At high GNPs content (9,12 wt %), GNPs are widely distributed in PP matrix and the thermal paths are basically formed. The thermal conductivity of composites is determined by the size and thermal properties of GNPs. At low GNPs content (6 wt %), for single system, the larger diameter with moderate distribution would be more conducive to achieve the higher thermal conductivity, indicating the formation of thermal paths dramatically affects the thermal conductivity. For hybrid system, the PP filled with medium and small diameter GNPs obtains the highest thermal conductivity at the ratio of medium diameter GNPs to small diameter GNPs is 8:2, and is 23.8% higher than the single system of PP filled with small diameter GNPs. More precisely, the small diameter GNPs plays a role in connecting the scattered medium diameter GNPs, as mass thermal paths are formed. This shows that the distribution state by combining the synergistic effect of various GNPs significantly affects the thermal conductivity of PP/GNPs nanocomposites. Moreover, a numerical simulation dealing with the synergistic effect of different GNPs, is developed on the thermal conductivity of GNPs-reinforced PP matrix. The heat flux images demonstrate the existence of synergistic effect between different type of GNPs.

The homogeneous deformation of Zr-based bulk metallic glass composites is studied near the glass transition temperature, at various levels of reinforcement volume fraction. Through examination of the constitutive response, it is seen that the presence of in situ reinforcements increases the flow resistance of the glass dramatically. This strengthening effect is shown to arise from two separate contributions: load transfer from the amorphous matrix to the reinforcements, and changes to the glass composition and structure upon in situ precipitation of reinforcements.