| Rapid heat cycle molding(RHCM) is a new injection molding process based on rapid heating and cooling technologies. The most notable feature of RHCM is that plastic product can be got with high quality of surface at same production efficiency compared to conventional injection molding(CIM). However, the property of product is depended on its inner microstructure, so the relationship between microstructure and property should be researched to improve the quality of plastic and guide the industry production. In this paper, the relationship between microhardness and microstructure in RHCM has been investigated based on a series of experiments. The main works are as follows:1. Samples of RHCM were prepared for experiments which include measureing microhardness and observing microstructures. Isotactic polypropylene was selected as raw material,, plastic products were got by dynamic mold temperature control. A variety of instruments were used to test sample’s microhardness and microstructures. The parameters of multilayer structure, sphaerocrystal size, crystal nucleus and crystalline lamellar were acquired by SEM, POM and WAXD. The microhardness of different position was measured by Vickers.2. Research the relationships between sphaerocrystal size, crystal nucleus and microhardness. Exploring the process which how the molding temperature impact sphaerocrystal, multilayer mircohardness was tested at different position. The relationship between sphaerocrystal and microhardness was deeply probed..3. Investigate the relationships between crystalline lamellar and microhardness. The samples were taken from multilayer and the orientation of streaming at different molding temperature, and then analyse how the thickness of lamellar crystal impact the microhardness.The study try to establish the relationship between microhardness and microstrucutre, and provide a theoretical support for microhardnesss imporvemnt. |
PDF Full Text Request