Study Of Foaming Process Of Chemical Crosslinking Foamed Polyethylene And Cell Regulation

Chemical crosslinking foamed polyethylene (XPE) is a kind of environmental polymer product which is non-toxic, odorless and has good impact resistance, thermal insulation, electrical insulation and anti-corrosion ability. It also has the characteristic of heat preservation and good second processing. As a result, the application of XPE is rather widespread in many domains, such as car industry, packing, sports equipment, construction and so on.Predecessors had studyed a lot about extrusion foaming and so on of XPE, but it’s free foaming process had been studyed scarely. In view of this, we studyed the free foaming process of XPE systematacially. The properties of XPE have a lot to do with its bubble structure, which is closely related to technological condition and engineering factors during its process. To control the bubble size, this paper firstly studied the decomposition kinetics of pure foaming agent azodicarbonamide and which with activator ZnO in a single tube which simulate the foaming furnace. The decomposition kinetics of AC in polythene fusion was also studied. The results indicate that ZnO can reduce AC’s decomposition temperature and increase its decomposition volume. Secondly, cell nucleation and bubble expansion in polythene fusion were studied through both theory and experiment. The results indicate that there exists starting nucleation temperature210℃and best nucleation temperature230℃and increasing temperature is good for bubble expansion. Thirdly, the effect of engineering factors such as crosslinking temperature, foaming temperature, time ratio and gas velocity and aids such as ZnO and TAIC on bubble structure was studied. At last, research results in the tube furnace was tested and verified in a foaming furnace of pilot scale. The results indicate that increasing crosslinking temperature and time ratio of crosslinking and foaming are good for bubble of big size, increasing foaming temperature is good for bubble of good uniformity. When the mass ratio of AC and ZnO is25:1and TAIC mass percent is3%, the foaming result is good, which is good for bubble of good uniformity and improving productivity.