In this study, rice husk biochar/high-density polyethylene (HDPE) composites were prepared via melt mixing followed by extrusion. Effects of biochar content and testing temperature on the dynamic mechanical analysis (DMA) of the composites were studied. Morphological analysis of the rice husk biochar and composites were evaluated by scanning electron microscopy (SEM). The results showed that biochar had a positive effect on dynamic viscoelasticity, creep resistance and stress relaxation properties of the composites, but the creep resistance and stress relaxation of the composites decreased with the increase of temperature. SEM analysis showed that HDPE components were embedded in the holes of the rice husk biochar, and it is believed that strong interaction was achieved.

This study was first conducted to comprehensively investigate the potential of yak manure as a raw material to prepare fuel pellets. The effect of different parameters such as binder, pressure, and moisture content on pellet density and diametric compressing strength was investigated using a laboratory single pelleting press unit. Results showed that increasing the pressure can help to obtain high-quality fuel pellets. The pellet properties (density and diametric compressing strength) initially increased and then decreased with moisture content increase. By contrast, binder was not identified to promote density and diametric compressing strength. The parameters were optimized using the response surface method with central composite design to obtain high-quality pellets. In conclusion, the use of yak manure as a raw material to make fuels can be considered a sustainable approach and can effectively be used to fulfill the energy and heating requirements of rural areas.