Preparation Of Pre-foamed Particles Of Polypropylene Resin By ～(60)Co-γ Irradiation

Due to its highly availability, light weight, easiness to recycle, and excellent performance, Polypropylene(PP) is one of the world's most popular resin. PP foamed material has become the hot spot in the plastic industry because of its heat-resistance, insulation and obstructive ability.The product of PP foam include low foamed sheet, high foamed sheet and foam particle. Because of its uniform dimension and stable foam multiple, PP foam particle is used widely and suitable for molding. Research of PP foam particle in china was far behind; most of the pre-foamed particle applied in auto industry and packing industry was imported. Due to the crystallization of PP, melt strength dropped quickly above melting point, that make foam molding became difficult. In order to be able to produced good foaming properties of polypropylene Pre-foamed particles. In this study, we focus on the contents as followed:1.High melt strength polypropylene was prepared by the initiation of ⁶⁰Co-γ, radiation in nitrogen environment, polyfunctional acrylate monomers used as the radiation sensitizes. Influences of the functionalities, the amount of the radiation sensitizes and dose of radiation on the gel content and melt strength were investigated.2. Use the melt strength polypropylene as raw material, pre-foamed polypropylene particles be prepared. Compared it's foam density and the cell morphology with the ordinary polypropylene particles.3. Pre-foamed particles of polypropylene was made from HMSPP. The effects of vesicant, nucleating agent, gel content of HMSPP and process on particle foam density were studied. The results showed that foaming performance was good when the pre-foamed particles with the content of high melt strength polypropylene was 100 parts, the content of AC was 6 parts and the content of Sio₂ was 2 parts.4. The tensile strength, impact strength, bending strength, Shore hardness, Dimensional Stability, Superabsorbent, and Thermal Conductivity of PP were characterized after foamed by particle。These properties were compared with other foams.In this study, High melt strength polypropylene was prepared by ⁶⁰Co-γradiation。PP foam particle was prepared by HMSPP. The technics and process of PP foam particle were studied。This research broke a path to expand applied fields of Polypropylene and to prepare high melt strength polypropylene at home.