Application Of Microwave Heating In Rotational Molding

Rotational Molding, also known as rotomolding, mostly used as processing of hollow plastic products. The development of Rotational Moulding grew faster than other plastic processing as injection molding or extrusion for its lower cost and fine products, which given extensive attention by the plastic industry. The industry of rotational molding in China presently enjoy a period of rapidly increase.Similar with other plastic processing methods, the rotational molding also has some disadvantages, just like long processing cycle, high energy consumption and limitation of plastic materials for use. So the main purpose of this paper is to discussing the heat property of polyolefin plastic under the microwave radiation and investigating the feasibility of the use of microwave heating in rotational molding. The microwave processing has been used in the experiment, also some additives which could absorb microwave were used compounding with plastic. Selected Carbon black, NdFeB and Al₂O₃, mixing with HDPE, LLDPE powder respectively, took the test for their microwave heating property under microwave radiation. Results showed that, the microwave heating property of carbon black was the best of three additives, and NdFeB and Al₂O₃ only could achieve the purpose in much higher content of those. Also some other methods as HDPE granules, compounded additive and in-continuous processing have been introduced into the experiment to improve the microwave heating effect of the blends.Finally, a special design of visible rotational molding equipment using microwave heating has been done for laboratory use. Then rotational foaming molding of LLDPE has been done. Results showed a nice surface of the products, which could confirm the next step of the research on foam mechanism.