Research On The High-Melt-Strength Polypropylene For Foaming Prepared By Reactive Extrusion

PP foam has become a new favor of the field of foaming in the 21st century owing to its wonderful mechanical property and heat resistance, its reclaimable and degradable properties, etc. The prospect of PP foam's application is very tempting. However, the traditional PP can not realize an effective foaming due to its poor melt-strength and strong crystalline performance. It is the most pivotal technology to research for a simple, low costing and effective method of preparing high-melt-strength PP (HMSPP). In this thesis, based on detailed experiment and study, a novel one-step silane cross-linking and grafting method, realized by modifying traditional PP using reactive extrusion, has been used to prepare HMSPP with partial cross-linking (the melt strength is four times of the pre-grafted). The research was funded by Qingdao Municipal Science and Technology Commission, and a correlative patent has been applied for. At the same time, the high-quality foam with fine, uniform cells and high close-cells degree has been fabricated successfully using HMSPP and a composite foaming system adding nanometer nuclear agents, which was made in our lab. This novel method opens a new approach for the preparation of PP foam, which has great prospect for application. This paper studies the influence of material prescription, art of preparation, etc. on the properties of partial cross-linked HMSPP in detail, and the reactive mechanism is also explored. 1. Research on "one-step" silane cross-linking and grafting PPFor the first time, using traditional isotactic PP, the peroxide as an initiator, unsaturated silane as a grafting monomer, multi-functional compound as a grafting coagent and a special catalyst, a partial crosslinked PP with high melt strength is prepared successfully by the reactive extrusion in twin-screw extruder. During the process, the grafting and partial cross-linking of PP occurred simultaneity (named "one-step"). Furthermore, the national patent has been applied. The influences of type...