Tang Zhihong

Thermal Properties of Poly(vinyl chloride-co-vinyl acetate-co-2-hydroxypropyl acrylate) (PVVH) Polymer and Its Application in ZnO Based Nanogenerators

A novel piezoelectricity based nano energy conversion device using vertically aligned ZnO nanowires/PVVH matrix as the working unit is proposed. Thermal energy is converted to electricity via the interaction of the PVVH polymer and ZnO nanowires. The thermal properties of PVVH are studied using Raman spectroscopy under different temperatures. The results show that the structure of PVVH is sensitive to fluctuations of the environmental temperatures. With the increasing temperature, PVVH tends to be crystallized and stress can be developed inside the polymer. The stress is responsible for the deformation and voltage generation of the ZnO nanowires.

Preparation and dispersity of carbon nanospheres by carbonizing polyacrylonitrile microspheres

Polyacrylonitrile microspheres of about 240 nm were synthesized and used as a precursor for preparing carbon nanospheres (CNs) by oxidation and sequential carbonization. The relationship between preparation conditions and sphere properties (dispersity and yield) were investigated. For oxidation, a slow heating rate resulted in good dispersity and high final temperature led to high yield of carbon. For carbonization, a slow heating rate and a fast flow rate of protection gas were good for the high dispersity of CNs. Under optimized conditions of 0.1 °C min−1 to 300 °C for oxidation and 3 °C min−1 to 1000 °C for carbonization under N2 protection of 1.8 L min−1, CNs with 180 nm diameter, 4.51% nitrogen content, high purity, and good dispersity were fabricated. Moreover, after being further treated at 2800 °C, graphitized CNs with high crystal structures were obtained.