Pi Pihui

Preparation and Characterization of Raspberry-like SiO2 Particles by the Sol-Gel Method

Raspberry-like SiO2 particles with a nano-micro-binary structure were prepared by a simple sol-gel method using tetraethoxysilane (TEOS) and methyltriethoxysilane (MTES) as precursors. The chemical components and morphology of the SiO2 particles were characterized by Fourier transform infrared spectroscopy (FT-IR) and a Transmission electron microscope (TEM). The surface topography and wetting behaviour of the raspberry-like SiO2 surface were observed with a Scanning electron microscope (SEM) and studied by the water/oil contact angle (CA), respectively. The thermal stability of the prepared SiO2 particles was characterized by TGA analysis. The results show that the highly dispersed SiO2 particles initially prepared by the sol-gel method turn into raspberry-like particles with during the aging process. The raspberry-like SiO2 particles show superhydrophobicity and superoleophilicity across a wide range of pH values. The SiO2 particles were thermally stable up to 475°C, while above this temperature the hyd...

Analysis of most probable mechanism functions and thermal degradation kinetics of n-phenylmaleimide-styrene-maleic copolymers

The thermal degradation kinetics of N-phenylmaleimide-styrene-maleic (NSMA) anhydride copolymers was analysed by a non-isothermal kinetic method. Kinetic parameters were obtained using integral and differential methods, and the most probable mechanism functions and kinetic compensation effects were discussed. The activation energy E for the thermal degradation of NSMA was 211.34kJ/mol according to the Flynn-Wall-Ozawa method and the thermal degradation was a first-order chemical reaction. A recommended rate expression for the thermal degradation reaction of NSMA was d α d t = A e − E R T ( 1 − α ) (where α is the conversion, t is time, R is the gas constant, T is the temperature and A is the pre-exponential factor), and the mathematical expressions of compensation effects for the integral and differential methods were lnA=-1.8037+0.1749E and lnA=-2.1974+0.1741E respectively.

Manufacturing and characteristics of copper clad laminates based on glass cloth and polytetrafluoroethylene

This study concerned the manufacture of copper clad laminates using glass cloth/pol ytetrafluoroethylene(PTFE), and the effects of silane treatment on the flexural strength and morphology of the resulting prepregs. About 40 wt% glass cloth in PTFE gave the highest flexural strength. The adhesion to copper was greatest when the glass cloth content was 20 wt% in the prepregs. Finally, the prediction of the dielectric properties was discussed.