Preparation Of Microcellular Foam PS/PP Reflective Plate Using Supercritical Carbon Dioxide

Microcell foamed polymer is a kind of porous material with the cell size of from0.1micron to tens microns. The industrial production of microcell foamed polymer has become a reality, due to the application of supercritical fluid technology on the porous foam material. Called as "novel materials for21Century", plastic foams have found a number of applications in the fields of energy absorption, thermal, and sound insulation.In this paper, through supercritical carbon dioxide foaming technique, using PS, PP, and their blends as the substrate, we successfully prepared a reflective plate material applicable to the LED lamps and advertising lamp box. The relationship between the process of supercritical carbon dioxide foaming and the cell structure, meanwhile, the relationships between the cell structure and the reflectance and the mechanical properties, were studied respectively.Firstly the microcell foamed reflective plate of PS was prepared. Then the performance of impact resistance, anti-bending, reflectivity, hiding rare and the bubble pore morphology of the microcell foamed PS were tested. It was found that the foamed PS had high reflectivity and hiding power, but poor impact resistance and bending property. Therefore, polypropylene, having a relatively tough mechanical property, was investigated by using the same way. The results showed that, compared to the microcell foamed PS, the microcell foamed PP had good impact resistance and flexural property, but its reflectivity and hiding rate were not enough. Furthermore, the blends with various PS/PP compositions were prepared, and the phase compatibility was improved by introducing the compatilizer. Then the foaming and the performance testing were carried out for the blends, too. It was found that the microcell foamed PS/PP blends combined excellent mechanical and optical properties of foamed PS and foamed PP. It was believed that its performance has basically met the requirement of LED reflector.The optimum technical parameters should be:1:3mixing ratio of PP and PS, applying of compatible agent, dwell time of16h, foaming temperature of60℃, foaming pressure of31MPa. The sample prepared under those conditions has been found possessed the properties of RB value of96.3%, RW value of96.5%, cover rate of99.79%.