| 2010th Bachelor |
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Title: Study on Thermal Properties of Nylon 6 Composites Filled Multi-walled Carbon Nanotubes with Organic Montmorillonite Writer: Yinglong Deng Supervisor: Wei Wu, Lixing Luan Abstract:Polyamide6 (PA6), PA6/MWNTs and PA6/oMMT nanocomposites were prepared by melting blending. Thermal Gravimetric Analysis (TGA) was applied to record the thermal degradation behaviour under nitrogen (N2) atmosphere with different heating rate. Both Kissinger Method and Ozawa Method were adopted in evaluating the activation energy (Ea) of PA6 nanocomposites. The enhanced heat resistance of PA6 matrix by nano particles were well observed. Differential Scanning Calorimetry(DSC) was applied to record the isothermal and nonisothermal crystallization behaviour. Avrami method was used to calculate the isothermal crystallization behaviour and Ozawa method was used to calculate the nonisothermal crystallization. The result suggested the effect of the loading of nanoparticles.
Title: Glycidyl Methacrylate Grafted SEBS Modified Nylon 6 / Montmorillonite Nano Composite Materials Research Writer: Wei Fan Supervisor: Wei Wu, Sanxiong He Abstract:SEBS-g-GMA toughened PA6/OMMT nanocomposites were prepared by melt compounding using co-rotating twin-screw extruder followed by injection molding. X-ray diffraction (XRD) and scanning electron microscope (SEM) were used to characterize the structure and morphology of the nanocomposites. The mechanical properties of the nanocomposites were determined by tensile, flexural, and notched Izod impact tests. Thermal properties were studied by using thermogravimetric analysis (TGA) and differential scanning calorimetry(DSC). Results showed that the presence of SEBS-g-GMA would improve the impact strength of the nanocomposites, while OMMT could improve strength and stiffness. XRD and DSC results revealed that the presence of SEBS-g-GMA and OMMT was favorable for the formation of the less stable γ-form crystals of PA6. The incorporation of SEBS-g-MA also favors the intercalation of macromolecular chain of PA6 into the interlayer spacing of clay. As for the rheology study, the viscosity decreased with the increasing amout of SEBS-g-GMA, but increased with the incorporation of OMMT. However, overweight of OMMT would decrease the viscosity caused by orientation and slippage of silicate layers in the PA6 matrix. When comparing the effect of SEBS-g-GMA with SEBS-g-MAH in toughening PA6/OMMT nanocomposites, it turned out that SEBS-g-MAH was a better toughener, with smaller particle size and better droplets dispersion as displayed in the SEM photos. Moreover, the incorporation of GMA which is propitious to enhance the interaction between PA6 and SEBS-g-MAH into the PA6/SEBS-g-MAH/OMMT nanocomposites slightly reduced the strength but obviously improved the toughness of the material, proved to be an ideal tougening system because of the synergistic effect.
Title: Preparation, Structure and Properties of PA6/SEBS-g-MAH/OMMT Three Nano Composite Material Writer: Zhufeng Fu Supervisor: Wei Wu, Sanxiong He Abstract:In this paper, SEBS-g-MAH is mixed with Nylon6 and OMMT to prepare the Ternary Nanocomposites--PA6/SEBS-g-MAH/OMMT via twin-screw extruder. The mechanical properties, thermal properties and rheological properties were studied by changing the components, grafting ratio and blending sequence. The results showed that when the OMMT was added, the flexile strength was increased by 42.8% and the tensile strength was increased by 26.5% than the pure nylon 6, respectively. SEBS grafted with maleic anhydride was more effective than pure SEBS in toughening Nylon 6 and the grafting rate of 1.2% was the best. By adding OMMT, the performance of the material was improved significantly. At the same time, when the proportion of PA6/SEBS-g-MAH/OMMT was 80/20/4, the properties proved to be the best and the viscosity was better than others. It was found that there were some differences when the blending sequence was changed. The product prepared by mixing the PA6 and OMMT first, then adding the SEBS-g-MAH resulted to be the best, whose impact strength was 98.4% higher than the product which prepared by mixing SEBS-g-MAH and OMMT first, then adding PA6.
Title: Cyclodextrin Precision Synthesis and Characterization of Graft Polyrotaxane Dime Fatty Acid Based Polyester Material Writer: Qizhen Lu Supervisor: Wei Wu, Yujie Chen Abstract:This subject adopts DFA(dimer fatty acid) EG(ethylene glycol) MAH(maleic anhydride),after condensation reaction to prepare the unsaturated polyester—the main chain,then curing by PS to get the granulometric resin.The preparation of DFA-EG-MAH-PS-GMA-β-CD based the resin grafted with GMA and β-CD(β-cyclodextrins). Pseudorotaxane was prepared by inclusion complexes of benzoic acid with β-CD.The characterization of unsaturated polyester, DFA-EG-MAH-PS-GMA, DFA-EG-MAH-PS-GMA-β-CD can be identified by FTIR.By uv-vis spectrophotometry can identify whether the inclusion complexes is generated,and according to the result of uv-vis spectrophotometry can determine the best ratio of nGMA:nPS cause the best yield of inclusion complexes and the highest reaction ratio. pseudorotaxane with supramolecular structures can be assembled based on non-covalent interactions.Among them,the assembly of cyclodextrins and macromolecules becomes the focus recently due to their advantages of selectivity,regulating capability,biocompatibility and other interesting properties.
Title: Synthesis and Characterization of Thermoreversible Crosslinking Supramolecular Polymer Containing Weak Multiple-hydrogen Bonds Writer: Jiawei Wang Supervisor: Wei Wu, Yujie Chen Abstract:Supramolecular polymer which is defined as monomer units is assembled by reversible and orientation non covalent bond interaction (subprime interaction) in block and solution and perform the properties for polymer. Self-assembly of rubber flexible system aggregated by small molecular obey the concept of supramolecular polymer. Dimeric substance assemble the long chain molecules by directional connection with polymer-like properties in block or solution. By mixing dimeric substance and other oligomers together, a network by physical associations will be constructed. In this strategy amide oligomer is obtained by polycondensation with dimer acid mixture and excess ethylenediamine with nitrogen atmosphere, after the amide oligomer have further reaction with phenyl sulfonylurea acylated isocyanate then we get the final products. In the product the functional groups of carbonyl and sulphone will form an association with amino group which is able to form self-complementary multiple hydrogen-bonds that lead to the formation of supramolecular networks and the thermoreversible properties. Using of analysis and test methods such as Fourier infrared spectroscopy (FTIR) analysis, the dynamic mechanical analysis (DMA), gel chromatography analysis, X-ray diffraction analysis and nuclear magnetic resonance analysis were very effectively to research the main component, system of mechanical properties and molecular weight distribution of sample.
Title: Preparation and Research of Polypropylene/Wood Fiber Composite Materials Writer: Jin Wang Supervisor: Wei Wu, Ru Wang Abstract:Wood Plastic Composites(WPC) is a kind of modified thermoplastic materials filled with wood fiber or vegetable fiber, which could be extruded or suppressed as profile, plates or something else to replace both the wood and plastic. In this paper, polypropylene (PP) /Wood fiber composites were produced by twin-screw extruder granulation. In order to modify the compatibility of the wood fiber and PP, three compatibilizers (PP-g-MAH,SEBS-g-MAH,EPDM-g-MAH)were used . The influences of compatibility on the properties of the wood/plastics composites were studied. We purpose a further attempt reinforcing PP/Wood fiber composites, and mechanical properties, moisture resistance, thermal stability and crystallinity, ect, were systematically studied. The results indicated that the water absorption and flexural modulus were raised, but most mechanical properties, crystallinity, rheological behavior, thermal stability drop with the increase of more wood fibers. Among the three compatibilizers(PP-g-MAH, SEBS-g-MAH, EPDM-g-MAH), comparing with the mechanical properties, PP-g-MAH has the best enhancing effect., and when the ratio of PP-g-MAH was 10%, PP/wood fiber composites has the best integrated performance. The MAH group on the PP-g-MAH can react with hydroxy group on the surface of wood fiber and reduces the content of the hydroxy group. So, the water absorption of PP/wood fiber composites is decreased. The results of infrared spectrum indicated that there was a absorption peak at near 1714cm-1, which was the characteristic absorption peak of ester bond, vertifying that anhydride functional group of PP-g-MAH can take place esterification reaction with hydroxy group on the surface of wood fibers. Based on the analyzing the SEM photos, we found that the phase between wood fibers and PP was clear without any compatibilizer, which showed that the interfacial bonding of PP and wood fibers was poor. When PP-g-MAH was joined in, the interface was invisible, indicating that PP-g-MAH can enhance the dispersibility of wood fiber in the basis of PP, and improve the compability of PP and wood fiber, and eventually enhance the workability and physical mechanical capability of compities.
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