Papers by Author: Yu Sun

Abstract: Abstract: An epoxy based nano-SiO₂/TiO₂/polyimide hybrid enhanced sizing for carbon fiber was prepared by modified SiO₂/TiO₂ precursor in PAA collosol with silane couple agent(WD-50) and eligibility surfactant via sol-gel reaction, and both ultrasonic cavitation and multi-complex technology were used during the process. The properties of PAA-SiO₂-TiO₂ hybrid sizing and micro-morphology of carbon fiber surface were analyzed by FTIR, DSC, Particle Size Analyzer and STM. The results indicated that nanoscale SiO₂•TiO₂ particles dispersed in the hybrid sizing film homogeneously, and a layer with nano particles was formed on carbon fiber surface after treated by the hybrid enhanceing sizing. The roughness was increased and interface properties of carbon fiber would be improved. At the same time both tensile strength and the interlaminar shear strength were increased obviously.

Abstract: Amino silicone (PDMS) with lower viscosity were synthesized at a certain temperature by ring opening copolymerization of octamethylcyclotetrasiloxane (D4), N-β-aminoethyl-γ- aminopropyl methyl dimethoxysiloxane (YDH-602), hexamethyldisiloxane (MM) with KOH as catalyst and DMSO as accelerating agent. The chemical structure was characterized via IR and 1HNMR. And the important factors were investigated carefully and the best technology of synthesis was obtained: reaction temperature 100-110°C, time 3h, KOH 0.05%, DMSO 0.5% and MM 5-7%, distilling at 110°C/0.095Mpa for 40 min.

Abstract: Nowadays, the stability of the mixed solution usually is improved by adding appropriate amount of emulsifier needed in many oil products, in order to reach the better effect of solution mulsification. In this paper, using silica gel column seperation to isolate pure ingredient of the emulsifier component, and all molecular structures prepared on silica gel were characterized by Fourier transform infrared (FTIR) spectum and silid-state 1H NMR experimental observations.

Abstract: Two kind of polyimide/silica nanocomposites which were recorded poly(amic acid)/ silica(PAA/SiO₂) and SiO₂ in poly(amic acid) ammonium salt(PAS/SiO₂) respectively, have been prepared for different methods. The size of SiO₂ in PAA/SiO₂ and PAS/SiO₂ are measured by Particle size analysis and the average particle size are 377nm and 53.7nm. Transmission electron microscopy(TEM) images of PAS/ SiO₂ confirm that the size of particles are ranged from 40 to 80nm. The stuctures of samples have been characterized by FT-IR spectra. The thermal stability of PAA/SiO₂ and PAS/SiO₂ are studied by thermogravimetric analysis (TGA) and the thermal behaviors were investigated by differential scanning calorimetry (DSC) in this paper. It is shown that PAA/SiO₂ have slightly better thermal properties than that of PAS/SiO₂. The results obtained from Instron universal strength tester present the water-solube PAS/SiO₂ own the excellent mechanical prperties as same as PAA/SiO₂.

Abstract: This first part of this paper will introduce the mechanical-dynamical properties of polysiloxane defoamer thoroughly. Defoamers or foam breakers are added to eliminate the existing foam and usually act on the outer surface of the foam because a bubble is a closed system and the defoamer can only reach the outer surfaces. Then, some of synthesis methods and compounds under real application conditions are given, such as synthesis of methyl hydrogen silicone oil, synthesis methods of polyether and compounds of polyether modified polysiloxane defoamer.

Abstract: Polyamic acids (PAA) were synthesized by solution polycondensation of aromatic diamine with dianhydride and PAA were readily soluble in polar organic solvents (N-methylpyrrolidinone, N, N-dimethylacetamide and DMF). It was found that the most appropriated reaction conditions of synthesis of PAA solution were the ratio of dianhydride with diamine being 1.02:1and 3h reaction time at ambient temperature in both N-methylpyrrolidinone and N, N-dimethylacetamide polar organic solvents. PAA thin films were prepared by PAA solution spread on the glass plate and PI thin films were obtained by the casted thin films which underwent a special high-temperature (300°C, 2h) heat curing. The structures of PAA and PI films were characterized by FT-IR spectra and degree of imidization of PAA solution was indicated from IR spectra. The thermal stability was studied by thermogravimetric analysis (TGA) and the thermal behaviors were investigated by differential scanning calorimetry (DSC) in this paper. It was shown that PAA solution were imidization at 200°C mostly and PI had higher thermal stability.

Abstract: A novel PEG200 lauric acid diester was synthesized high yield by direct esterification using polyethylene glycol and lauric acid respectively was presented in this work. The product of PEG200 lauric acid diester was characterized by a fourier transform infrared spectrometer(FTIR). The effects of catalyst, reaction time, reaction temperature and molar ratio on the reaction were discussed. The optimum synthetic condition of PEG200 lauric acid diester: esynthesis is based on protection of N₂ and the ressure is 0.08Mpa. Using mass fraction 0.45% in p-toluene sulphonic acid as catalyst, molar ratio of polyethylene glycol and oleic acid 1:1.95, reaction temperature about 130-140°C, and reaction time 9-10h. The results of testing of diester products showed that the yield of PEG200 lauric acid diester is 98.2%.And this article reviewed the effect of concentration on viscosity. The characteristic curve of Viscosity-Concentration showed the viscosity increased with increase of the concentration which brought about the increase of particle size. Especially focusing on the maximum viscosity appeard on 80% because of the phenomenon of reverse micelles. Then the viscosity decreased with increase of the concentration.

Abstract: In this paper, with fatty alcohol polyoxyethylene (AEO9), succinic anhydride (SA) and sodium hydroxide as raw materials, a new type of fatty alcohol polyoxyethylene carboxylate surfactants (SAE9C-Na) was obtained by esterification and neutralizing effect. The influencing factors were researched and its surface properties were studied. The optimum condition of synthesis was determined: molar ratio of alcohol to acid was 1:1.1, reaction temperature was 85°C, reaction time was 60 min, under this condition, the yield could reach up to 95.8%. The results received from this experiment showed that SAE9C-Na had excellent surface activity and foaming and foam stability, whose emulsification and solubility enhancement were improved greatly.