Fang Pengfei

Microstructure and surface state of plasma-treated high-density polyethylene elucidated by energy-tunable positron annihilation and water contact angle measurements

High-density Polyethylene Elucidated by Energy-tunable Positron Annihilation and Water Contact Angle Measurements Zhe Chen1,2,∗, Zhi Wang1,2, Qiuming Fu1,2, Zhibin Ma1,2, Pengfei Fang3, and Chunqing He3 1Hubei Key Laboratory of Plasma Chemistry and New Materials, Wuhan Institute of Technology, Wuhan, 430073, China 2School of Material Science and Engineering, Wuhan Institute of Technology, Wuhan, 430073, China 3School of Physics and Technology, Wuhan University, Wuhan, 430072, China

Preparation and structural characterization of polystyrene-rectorite nanocomposites

The polystyrene/rectorite nanocomposites were prepared by free radical polymerization of styrene containing dispersed organophilic rectorite. The structures and thermal properties of these hybrids have been investigated by X-ray diffraction (XRD), fourier transform infrared (FT-IR), positron annihilation spectroscopy (PAS) and thermal gravimetric analysis (TGA) techniques. It was found that exfoliation of rectorite in polystyrene (PS) matrix was achieved. The average free-volume radius in the PS/clay nanocomposites is generally same as that in PS. Along with increment of rectorite contents, the interface between rectorite and polystyrene matrix increases, and the free-volume concentration decreases obviously. And the polystyrene nanocomposites have higher thermal decomposition temperature than pure PS.

Positron Annihilation Mechanism Correlated with Microstructure of C60-Contained Chitosan

Positron annihilation lifetime spectra measurements were performed on C60-containing chitosan as a function of temperature ranging from 290 to 380 K. Both the ortho-positronium annihilation lifetime τ3 and its intensity I3 increase with increasing temperature, however, the values of I3 in C60-containing chitosan are smaller than that in pure chitosan, and the slope of τ3 with temperature is also suppressed after C60 linked. The existing three models for positron annihilation in polymer have been compared to analyze the experiment result. It is realized that only the spur reaction model, combined with the free volume model, can explain it satisfactorily. The ortho-positronium lifetime and intensity were affected by the local physicochemical environment of material, i.e., free-volume structure, electron scavenging and trapping sites, etc. The linked C60 that play a significant chemical inhibition and quenching role on positronium formation and annihilation is first observed. The microstructure change brought by C60 group has also been discussed.

The Effect of Curing Agent Content on Photodegradation of Epoxy Coating Studied by Positron Annihilation

The photodegradation progress of epoxy cured with polyamide and the effect of the curing agent content under UV-A irradiation have been investigated using positron annihilation spectroscopy with an energy tunable positron beam. After 88 h of irradiation, a post-cure process and the generation of carbonyl groups reduce the value of the S parameter, compared with the virgin samples. As the irradiation time increases from 208 h to 399 h, the S parameter decreases, which may be due to the growth of carbonylgroups and the generation of free radicals. After 543 h of irradiation, a dead layer with very low S value appears near the sample surface probably induced by a dramatic decrease in the Ps formation probability. The positron results also reveal that epoxy cured with an appropriate amount of polyamide has a smaller dead layer suggesting that the amount of curing agent is a key factor affecting the photodegradationof epoxy resin.

The surface structure and hydrophobic recovery of poly-dimethylsioxane insulator after ar plasma treatment

Feng Zheng1, Chunqing He1, Pengfei Fang1,∗, Zhe Chen2, Shaojie Wang1,∗, Jianguo Wang3, Xiangyang Peng4, and Zhihai Xu4 1Department of Physics and Hubei Nuclear-Solid Physics Key Laboratory, Wuhan University, Wuhan 430072, China 2Department of Material Science and Engineering, Wuhan Institute of Technology, Wuhan 430073, China 3School of Electrical Engineering, Wuhan University, Wuhan 430072, China 4Guangdong Electric Power Research Institute, Guangzhou 510080, China

Synthesis, Characterization and Catalytic Hydrosilylation Activity of (60) Fullerene n-Propylamine Platinum, Rhodium Complex

Fullerenen-propylamine platinum, rhodium complex have been prepared from C60 via amination withn-propylamine, then reacting respectively with potassium chloroplatinite or rhodium chloride. The two noble metal complexes can effectively catalyze hydrosiiylation of olefins with triethoxysilane. The Pt complex exhibits high regioselectivty for styrene, nearly 100% branched product is obtained.

Supramolecular Chemistry Functionalization of [60]Fullerene with Vaporous Reagents via Its Calix[8]arene Complex

Abstract A new approach to functionalization of fullerene is developed: treating [60] fullerene p-tert-butyl calix[8]arene complex with vaporous reagents, such as chlorine, vaporous bromine or vaporous amines. A dramatic reaction acceleration was observed and derivatives with smaller substitution degree were obtained in the reaction in comparison with the reaction of [60]fullerene itself The influences of temperature and gas flow rate were investigated.