| Polyvinyl chloride(PVC) is one of the five kinds of common thermoplastic around the world. Due to its unique property, it has been widely applied in various fields, and becomes one of the key developments of new materials in our country. However, on account of the certain defects in structure, certain amounts of thermal stabilizer were added into PVC during the actual machining process, in order to improve the heat stability of PVC products and inhibit the thermal degradation. At present, most of thermal stabilizers in the market exist some drawbacks, such as expensive, toxic, poor performance. The European Union has issued relevant laws and regulations that the heat stabilizer include lead would be totally banned using in PVC. Meanwhile relevant laws and regulations had also been put on the agenda in our country, which made it imminent in the research and development of avirulent and environmentally friendly thermal stabilizer. In nature, vegetable oil and bio-based materials are readily available, renewable, and green, which are unmatched by fossil raw materials.Therefore, the research based on the bio-based materials modified PVC heat stabilizer and compound application technology were investigated in this dissertation.Firstly, using erucic acid as raw materials, 30% hydrogen peroxide solution as oxygen source, formic acid and concentrated sulfuric acid as catalyst, epoxy erucic acid was prepared through the liquid epoxidation reaction. On this basis, calcium epoxy erucic acid and zinc epoxy erucic acid were prepared by double decomposition reaction. The epoxy groups with oxygen lone pair electrons were introduced to the molecular structure of products, which could produced a synergistic stable effect. Compared with traditional calcium stearate and zinc stearate, they had better long-term thermal stability. On this basis,1,3-dimethyl-6-semicarbazide pyrimidine(DMAU) and pentaerythritol(PER) and β-diketone were added to PVC as auxiliary heat stabilizer. As a result initial-term whiteness had been highly improved and "burn" zinc was depressed. What’s more, DMAU showed the most significant effect of thermal stability, the thermal stability mechanism was investigated between DMAU and calcium/zinc epoxy erucic acid system.Secondly, using a kind of lewis acid, anhydrous aluminum chloride as catalyst, bio-based zinc glycerol monostearate(ZnGlyA) was prepared with glycerol monostearate and zinc oxide,its structure was characterized by FT-IR, XRD, element analysis, TG and atomic absorption.The dosages of CaSt2 and ZnGlyA were 2.25 phr and 0.75 phr, respectively, which performanced the better thermal stability properties. Compared with the same amount traditional CaSt2/ZnSt2, thermal stability effect had been greatly improved. In order to further improve the performance of PVC material. On this basis, the system with semicarbazide pyrimidine(GNMD), calcium acetylacetonate(CaI), sodium perchlorate(NaClO4) as auxiliary stabilizer, the thermal stability was investigated with a variety of testing methods,the thermal stability performance of PVC was significantly improved.Finally, graphene has unique structure and good electrical conductivity, which was applied to CaSt2/ZnGlyA system. PVC/GR composites was prepared with mixed solution method, the results showed that adding 0.2 phr of grapheme, the tensile strength and hardnessof PVC samples increased by 8.38% and 20.63%, respectively. Static thermal stability time(TS) and thermal stability time(T2) with GR/GNMD of 2%(mass ratio of 0.2/1.8) reached at102.5 min and 124.5 min, which increased by 67 min and 49.5 min compared with CaSt2/ZnGlyA system, respectively. The results of thermogravimetry showed that the temperature(Tp) of maximum weight loss rate was 317.66 oC, which indicated the excellent synergistic effect between GR/GNMD and CaSt2/ZnGlyA system. SEM showed that GR dispersed in PVC specimens evenly, which played a role in the interaction between molecular chain. Graphene can significantly improve the conductivity of PVC products, which is expected to be applied to the conductive PVC plastic. |
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