Preparation Of Polycarbonate Foams By Supercritical Carbon Dioxide And Study On Its Property

The material of microcellular foams has attracted widespread attention in recent years with the continuing desire for lightweight materials in the industry of automotive,railway and construction.Microcellular foam is a new material for realizing the density of polymer materials while retaining the necessary mechanical properties.Its performance depends on the property of the polymer and its own cell structure.Polycarbonate?PC?is one of polymer materials with excellent properties which has excellent thermal stability,dimensional stability and mechanical strength.It is widely used in light,automotive and glass industries.In this paper,supercritical carbon dioxide?scCO₂?was used as a foaming agent.And PC closed-cell foaming materials and open-cell foaming materials were successfully prepared by batch foaming method.And we study their foaming behaviors.The PC microcellular foams was prepared using a homemade molding machine.And we systematically investigate the effects of temperature,CO₂ pressure,foaming time and PC induced crystallization by CO₂ on foaming behavior.The results show that the temperature,CO₂ pressure and foaming time are all important factors which affect the morphology of the final cell.PC closing foams materials with uniform cells and appropriate pore diameter can be prepared when the three conditions reach a certain condition at the same time.In addition,we also found that CO₂ can induce PC crystallization under certain temperature and CO₂ pressure conditions.And the degree of crystallinity increases with the increasing the foaming time which greatly limits the growth of the cells.we explore a new foaming process route in order to improve the efficiency of PC foams prepared by the compression foaming method based on this experiment.A pre-saturation process is added to this route to reduce the time which the CO₂ is ultimately completely dissolved in the polymer.It has been found that this new foaming process can greatly improve microcellular foaming efficiency without substantially changing the final results of the cells and the expansion ratio.PC/POE opening foam with multi-through pore structure was successfully prepared using POE by rapid blend method.It was found that the POE was uniformly distributed in the PC matrix in the form of spherical particles by analyzing the morphology of the PC/POE blend.The morphology shows a typical"sea-island"structure.And the spherical particle size increases with the increasing of the POE content.Then the effects of POE content and parameter on the morphology of PC/POE foamed cells were studied.The results show that The open pore structure can be obtained when the condition of 20%POE content,15Mpa CO₂ pressure and the 150^oC temperature.Finally,the opening mechanism of PC/POE blend foaming was also explored.