Papers by Author: Jian Hui Qiu

Abstract: Functionalized magnetic silica nanospheres were prepared by hydrolyzation of tetraethyl orthosilicate (TEOS) on Fe₃O₄ and modification of Fe₃O₄/SiO_x. Structure of functionalized magnetic silica nanospheres were characterized by transform infrared spectroscopy (FTIR) and differential thermal analysis (DTA). Cellulase was immobilized on functionalized magnetic silica nanospheres through cross-linking method. Saccharification rate of the immobilized cellulase is 70 % of that of free cellulase. The saccharification of the immobilized enzymes after 8 continuous uses still have 10 % of the initial saccharification rate, which demonstrate the potential of this immobilized cellulase for biofuel production.

Abstract: Functional floating bead (F-FB), prepared by anchoring the organic sulfonic acid on the surface of the blackberry-like structural FB, was used as both the inorganic substrate and the in situ dopant for the in situ chemical oxidative polymerization of pyrrole to obtain the polypyrrole/functional floating bead (PPy/F-FB) composites. The encapsulating morphologies were revealed with the scanning electron microscopy technique. The PPy/F-FB composites were characterized with Fourier transform infrared spectroscopy and thermogravimetric analysis. Based on the cyclic voltammetry of the composites, it was found that the composites performed typical electrochemical supercapacitor behavior.

Abstract: Lipase Novozym 435 was used as catalyst to degrade P(BS-co-DGS), which was a kind of PBS-based copolyester modified with diethylene glycol (DEG), in a THF/toluene mixed solvent system. P(BS-co-DGS) copolyesters were synthesized by copolymerization and characterized by ¹H NMR. GPC and TGA were used to investigate average molecular weight and thermal property before and after degradation, respectively. After degraded by N435 for 30 h, the M_n of P(BS-co-DGS)10 (DEG content 10%) decreased from 8.33×10⁴ to 3.52×10⁴ g·mol^-1 with some yellow oil droplets of oligomers appearing. And the initial decomposition temperature (the temperature at 5% mass loss) of P(BS-co-DGS)10 changed from 300.6 to 178.9. MALDI-TOF-MS results showed that none of DEG oligomers appeared in P(BS-co-DGS)10 degradation products. However, when the DEG content increased to 20%, there were the DEG circle oligomers as well as linear oligomers in the degradation products.

Abstract: In this work, the spring back, dimensional change, internal structure and morphology of extruded polypropylene were investigated in order to consider the rolling characteristic. It was found that the internal structure, molecular orientation and crystallinity were changed a little by high spring back under low reduction in thickness. Crystal structure was extended along the rolling direction with high reduction in thickness due to the increase of plastic deformation. As a result, molecular orientation increased and crystallinity decreased at over 30% of reduction in thickness. Crystalline structure of surface was similar to the center part in cross-section at 70% reduction in thickness, and molecular orientation was constant.

Abstract: The biodegradable composites were prepared with the oyster shell particles (OSP) and poly(lactic acid)(PLA) by injection molding. The mechanical and thermal properties were investigated. The degradation temperature of the composites decreased by increasing the content of OSP compared with PLA. From the results of tensile test, the tensile strength and the fracture strain of the composites decreased because of exist of OSP. However, the Young’s moduli of the composites increased compared with PLA. The SEM observation of morphology confirmed that the interface between PLA and OSP had poor adhesion.

Abstract: The present work investigated the variation of internal structure, molecular orientation, crystallinity and mechanical characteristics of polypropylene(PP) after rolling process. The materials plate became narrow when rolled from entrance to exit, and the internal crystalline gradually deformed and at last destroyed. Plastic deformation was discovered along the rolling direction. In this direction, the crystallinity and vickers hardness were decreased, and molecular orientation was increased. Moreover, molecular orientation had a sharp increase at the second half part of rolling sample. The tensile stress of rolled samples increased by 80% parallel to rolling direction and decreased by 22% perpendicular to rolling direction.

Abstract: To consider the effective utilization of agricultural wastes, rice straw/Poly (lactic acid) (PLA) composites were prepared by the mechanically compounding and injection molding. The water contents were increased with increasing the rice straw content. After natural weathering or burial in soil, more microcracks were observed on the surface of the PLA composites rather than the pure PLA. Moreover the tensile strength and the fracture strain of PLA composites were obviously decreased with increasing the weathering and burial testing term.

Abstract: To consider the effective utilization of plastics and agricultural wastes, rice straw fibre was extracted from agricultural wastes, and then composited with polylactic acid(PLA). The thermal stability of straw/poly(lactic acid)(straw/PLA) composites decreased (Thermogravimetric Analysis, TGA). Tensile strength, fracture strain and sharply impact strength of straw/PLA were decreased with the increase of filler content and grain size of straw. Yong’s modulus were increased as the increasing of straw content.

Abstract: Based on the novel USW method, the welds of Polylactide (PLA) - Polyformaldehyde (POM) and PLA - polymethyl methacrylate (PMMA) have been carried out. The interdiffusion processes of polymer chains have also been investigated according to the reptation theory and the hauling theory. The welding strengths are carried out by the universal tester and the rupture interfaces are observed using the scanning electron microscope. The best welding strength is 52MPa (90% compared with PLA of the PLA-POM system), which can reach the tensile strength of IPS. The molecules of POM are much easier to inter-diffuse than those of PLA and PMMA.

Abstract: Activated montmorillonite(MMT) was modified by toluene diisocyanate(TDI) and TDI-montmorillonite(TDI-MMT) was prepared. The characterization of TDI-MMT was carried out by X-ray diffraction(XRD) and fourier transform infrared spectrometry (FT-IR). The results showed that TDI had been inserted to the interlayer of MMT and the interlayer spacing of MMT increased by 0.26nm. With stannous chloride as catalyst, the biodegradable polylactide acid/TDI-montmorillonite(PLA/TDI-MMT) nanocomposites were synthesized through ring-opening polymerization of lactide in the layer of TDI-MMT by in-situ polymerization. The structure and thermal stability of nanocomposites were investigated by XRD, FT-IR and thermogravimetry (TG). Exfoliated nanocomposites were obtained as shown by XRD results. FT-IR spectra confirmed that TDI-MMT participated in the ring-opening polymerization of lactide. TG analysis indicated the decomposition temperature of nanocomposites rose and the thermal stability was improved contrast to the neat PLA. The effect of the content of TDI-MMT on the molecular weight and thermal stability of nanocomposites was studied. With the increase of the proportion of TDI-MMT, the molecular weight of resultant nanocomposites decreased and the decomposition temperature rose at the range of experiment research.