Papers by Author: Si Qun Wang

Abstract: In this study, rice straw (Oryza sativa L.) fibril and fibril aggregates (RSFs) material isolated by high intensity ultrasonication (HIUS) was used as reinforcement in an RSFs/Polypropylene (PP) nanocomposites. The morphology of RSFs was investigated by scanning electron microscopy (SEM). The mechanical properties were evaluated by tensile test. The fourier transform infrared spectroscopy (FTIR) test was also performed to investigate the interface compatibility between RSFs and PP matrix. Results indicated that the tensile strength of RSFs/PP nanocomposites increased with increasing cycle time of extruder from 10 min to 30 min at 180°C. The maximum value of tensile strength was 31.2 MPa appeared at the conditions of 190°C and cycle 20 min. The elastic modulus increased by adding 5 wt% RSFs into the PP/MAPP matrix. However, there was no distinct difference of elongation in RSFs/PP nanocomposites at different extruder conditions. The RSFs embedded into the PP/MAPP matrix and exhibited better interaction by FTIR test.

Abstract: Castor is one kind of excellent woody materials and can be used to make wood based panel instead of the wood materials. To use the castor stalk better, it studies the chemical composition including cellulose, hemicellulose and lignin by high performance liquid chromatograph (HPLC) and the standard of PRC respectively, the pyrogenation-characters by thermo gravimetric analyzer (TGA) and the relationship between chemical composition and the pyrogenation-characters by SAS. The results showed that the chemical composition and pyrogenation-characters are different in different layers of the castor stalk, besides the castor stalk is mainly pyrolysis in second stage (between 170-330°C).

Abstract: Castor- stalk is one kind of excellent wood materials can be used to make the wood based panel and substitute for the wood resource, reducing the pollution caused by castor stalk-burnt. The properties of the castor stalk based fiber panel are better than the properties of the castor stalk based particle panel made under the same techniques. It studied the infiltrating-characters, the radicals-concentration and the micro-structure of the castor stalk based panel with highly effective surface tension and angle of contact instrument, Electron spin resonating spectrum instrument (ESR) and Scanning electronic microscope (SEM). The results show that the wetting-soakage and the radicals-concentration of the castor fiber are worse than those of the castor particle. The micro-structure of the castor fiber is complete and smooth without crevasse in the castor stalk based fiber panel. But the micro-structure of the castor fiber is not complete and is bruised in the castor stalk based particle panel. So it show that the properties of the castor stalk based particle board are worse than those of the castor stalk based fiber board caused by the micro-structure changed maybe.

Abstract: Castor stalk is one of excellent woody materials.which is the byproduct of the castor oil plant. Itwas usually burnt without use at all when the castor seed were harvest. To use this resource, we studied the castor stalk based panel made with different resin including UF, PF and MDI resin. The results show that the properties of castor stalk based particle panel made with UF and MDI resin by certain techniques can reach the requirement of the standard of China expect the castor stalk based particle board with PF resin which will be studied further more.

Abstract: Castor-oil stalk is one kind of excellent woody materials, and the thickness swelling ( TS ) of the castor-oil stalk based panel with Urea- formaldehyde resin ( UF ) cannot meet the requirement of the Standard of People’s Republic of China. the TS of the panel was improved with wax emulsion.Results showed that the mechanical properties and the TS of the particle panels were improved as the wax emulsion loading increased. The TS of castor stalk based particle boards and fiber boards can meet the requirement of standard of PRC when 1.44 and 1.2 wt% wax emulsion, respectively, was added.

Abstract: Rice straw (Oryza sativa L.) pulp was treated by high intensity homogenizer to make fibril and fibril aggregates. The rice straw fibril and fibril aggregates (RSFs) material was used as reinforcement in a RSFs/ Poly (vinyl alcohol) (PVA) nanocomposite that prepared by film casting. The diameter distribution of RSFs was investigated by laser diameter instrument (LDI) and its crystallinity was evaluated by wide angle X-ray diffraction (WAXD). The morphological of RSFs was investigated by scanning electron microscopy (SEM). The mechanical properties were measured by tensile test and the dynamic mechanics analysis (DMA), thermal stability tests, i.e., differential scanning calorimetry (DSC) and thermogravimetric analysis (TG) and the Fourier transform infrared spectroscopy (FTIR) test were also performed, respectively.

Abstract: Advanced atomic force microscopy techniques such as contact resonance force microscopy, noncontact mode phase imaging, and scanning thermal microscopy techniques have been used to characterize material properties in the interphase of fiber reinforced polymer composites. With contact resonance force microscopy, the average interphase thickness was found to be (49 ± 5) nm, (64 ± 12) nm, and (139 ± 21) nm for samples containing lyocell fibers in matrix materials consisting of 100 % polypropylene (PP)/0 % maleated polypropylene (MAPP), 95 % PP/5 % MAPP, and 90 % PP/10 % MAPP, respectively. Clear distinctions in modulus values between the fiber, interphase zone, and matrix are clearly visible in modulus images. A gradient of modulus was observed across the interphase region that ranged between the modulus values of fiber and the polymer matrix. Noncontact mode images showed a clear phase difference between the fiber, interphase, and matrix owing to the difference in material properties between the components. Interphase regions were observed to possess higher thermal conductivity than the matrix polymer due to cross-linking within the interphase.