Papers by Author: Si Kai Zhou

Abstract: The influence of carbon doping on tribological properties of CrCN Coating was studied through preparation of coatings deposited on single crystal silicon and M2 high speed steel(HSS) substrate using closed-field unbalanced magnetron sputtering ion plating technique. The friction coefficients were measured by pin-on-disc set-up. The microstructure and bond states of the coatings were characterized by X-ray diffraxtion(XRD), transmission electron microscopy(TEM) and X-ray photoelectron spectroscopy(XPS). The results show that the friction coefficient of coating decreases from 0.75 to 0.38, the microhardness increases from 1930HV to 2302HV, and the specific wear ratio of the coatings decreases from 8.35110-5m3/Nm to 3.85910-5m3/Nm with the increasing of carbon target current(IC) from 0A to 1.5A. The analysis of microstructure shows that the coatings transform from crystalline state to amorphous state and the grain size of the coatings decreases with the increasing of carbon target current.

Abstract: In this paper, a system polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) were synthesized by nitroxide-medium controllable free radical polymerization. PS-b-P4VP were characterized by 1H-nuclear magnetic resonance (1H-NMR), infrared spectrum (FTIR) and gel permeation chromatography (GPC). The results have indicated that diblock copolymers can be prepared and with molecular polydispersities in the range of 1.08 to 1.31. The structure of diblock was showed by 1H-nuclear magnetic resonance.

Abstract: a system of polystyrene and polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) were synthesized by using living free radical in the presence of 4-hydroxyl-2, 2, 6, 6-tetramethylpiperridine-oxyl-1(HTEMPO•) and (BPO). The polystyrene and diblock copolymers were characterized by gel permeation chromatography (GPC) and atomic force microscope (AFM). The results suggested that the polymerization of styrene in the presence of 4-hydroxyl-2, 2, 6, 6-tetramethylpiperridine-oxyl-1(HTEMPO•) and benzoyl peroxide (BPO) can be prepared with molecular weight distribution in the range of 1.15 to 1.25. The polystyrene with living groups can continuously initiate the living free radical polymerization of 4-Vinylpyridine to form the polystyrene-block-poly (4-vinylpyridine) with molecular weight distribution in the range of 1.08 to 1.35. The AFM of diblock indicated the diblock copolymer（PS-b-P4VP） is a good compatibilizer for PS and P4VP.

Abstract: A series of blends have been prepared by adding a novel thermoplastic Poly (aryl ether) s containing phthalazinone moiety (PPAEs) in varying proportions to diglycidyl ether of bisphenol A epoxy resin (DGEBA) cured with p-diaminodiphenylsulfone (DDS). The glass transition temperature (Tg) of DGEBA /PPAEs blends were performed using differential scanning calorimetry (DSC) technique. It is proved that the addition of PPAEs resulted in enhancement of thermal properties of the blends, especially PPENK. There was moderate increase in the fracture toughness as estimated by notched impact strength. Compared to that of unmodified epoxy, the maximum toughness of the modified blends had increased 44% by addition of 15 phr PPENK. Fracture mechanisms such as plastic deformation and the ductile nature of the crack of the matrix were responsible for the increase in the fracture toughness of the blends.