Preparation And Properties Of Novel Degradable Plastic Films

In this thesis, the essential situation and research progress of degradable plastic are summarized. Several novel degradable polyethylene plastic films with a low cost and a superior performance are designed and prepared. This paper focuses on investigating the degradation performances of the films and the action mechanism under the synergistic action of light, heat and microorganisms. The main contents are as follows:TiO2-Kaolin-PE (TKPE) film was synthesized using nano TiO2as photo-catalyst and kaolin as biodegradable promoter, and the photo-degradation and biodegradation of the film were also investigated. The results showed that the weight loss rate for the film reached26.8%under UV light irradiation for240hours. The biodegradation rate of the photodegradable residues of TKPE film reached6.0%after60days of incubation in aqueous medium. The mechanical properties of the composite films were improved at the same time due to the lubricating effect of kaolin, which was helpful for the practical application of the film.A thermo-and biodegradable polyethylene film (MnSt2-Kaolin-PE (MKPE)) was prepared using manganese stearate as thermo-degradable additive and kaolin as biodegradable promoter. The thermo-degradation and biodegradation of the film were investigated. The experimental results showed the composite film could be effectively degradable after thermal treatment and the subsequent biological incubation. The mechanical properties of MKPE films reduced quickly after thermal treatment for8days at70℃. A mount of oxygen groups were introduced into the polymer chains and the carbonyl index achieved120%after30days of thermal treatment. The biodegradation rate of the residue after thermal treatment for the film reached24.26%after60days of incubation in aqueous medium.A photo-and thermo-double degradable polyethylene film (TiO2-FeSt3-PE (TFPE)) was prepared using nano TiO2as photo-catalyst and ferric stearate as thermo-degradable additive. The double degradable film solved the problem that a simple photo-degradable film could not continue to degrade when lost light irradiation. Results showed that the weight loss rate of the TFPE film under UV light irradiation for240h could reach10.60%. Its mechanical properties were almost entirely lost after15days of thermal treatment and the carbonyl index achieved79.20%after30days of thermal treatment. The biodegradation rate of the residue after thermo-degradation for the film could reach8.75%after60days of incubation in aqueous medium. To further improve the biodegradation rate of the TFPE film, TiO2-FeSt3-kaolin-PE was prepared by adding kaolin, which was used as bioactive agents, and the biodegradation rate of the residue was improved to14%.In addition, this paper had a simple discussion on the mechanism of photo-degradation, thermo-degradation and biodegradation of the films, which could provide a theoretical basis for the preparation of completely biodegradable polyolefin plastic films.