Visualization Observation Of Polymer Foaming Process

Polymer microcellular foamed materials are widely used in various fields of our lives because of their advantages such as low mass and light weight.It is well-known that the mechanical properties of polymer microcellular foams are important factors for their application in a wider range of fields,and the mechanical properties mainly depend on the cell structure(cell size,cell density,etc.).The formation of cell structures depends on the foaming process.Therefore,the research on the foaming process of polymer foams has received extensive attention.However,most of the current researches on the foaming process are based on the research of the foaming final state.The simulation of the foaming process through a certain theory can not determine the authenticity of the simulated foaming process and there are certain limitations.Therefore,this article based on chemical foaming,using a visualization system to study the foaming process of polypropylene composite.The study includes the stress of the foam during the foaming process,the migration orientation of the resin,and the relationship between cells and fibers.The aim of this paper is to provide a theoretical basis and guidance for the preparation of high-quality foamed polymer composites.The results show that:(1)The visualization system used in this paper is an effective means to study the foaming process of polymers.(2)This study establishes a correct migration model of the resin around the cell during the foaming process of polypropylene,and provides a new method—carbon fiber tracer,which validates the force of the cells and the migration orientation of the resin in the foaming process of polypropylene.(3)In the foaming process of PP/CF composites,in the less-foaming stage,the fibers with different content of different surface characteristics show the same regular characteristics;in the balance foaming stage,the addition amount of different fibers shows obviously different rules,and surface modification effectively inhibited the migration of the cells along the surface of the fiber,the number of fibers entering the cells was significantly less,but the cell deformation rate was higher than that of PP/unmodified CF composites;in the over-foaming stage,the cell deterioration was more and more serious.(4)In the foaming process of PP/AF composites,the fibers with different content of different surface characteristics in the nucleation stage show the same regular characteristics;during the middle period of foaming,the cells grow along the direction of fibers.The surface-modified AF effectively inhibits the migration of the cells along the surface of the fiber.During the process of the fiber entering the cell in the late stage of foaming,the cells show a regular pattern of recovery after deformation,which significantly reduces the irregularity of the cells.(5)Comparative study of the foaming process of PP/CF composites and PP/AF composites with different content and different surface characteristics shows that the effects of rigid addition phase and toughness addition phase on the foam process have differences and similarities.And for the micro-foamed polypropylene/fiber composite materials,it is particularly important to control the foaming endpoint in the balance foaming stage in actual production.