A new core-back foam injection molding method with chemical blowing agents

This paper presented a new core-back chemical foam injection molding (CFIM) method. Different from the conventional method, the new method has a unique secondary filling stage right after core-back operation. By combining core-back and secondary filling, a closed shell composed of dense polymer skins can be created right before melt filling. This closed shell can prevent the gas loss from the melt flow front, and act as the gas counter pressure to reduce cell coalescence and collapse, thus leading to significant improvement of cell structure. The mechanical testing results show that the new technology can produce plastic foam with simultaneously enhanced tensile strength, elastic modulus, and notch impact strength. Moreover, this technology can also improve the surface appearance of the foamed sample. Thus, it shows a promising future in offering lightweight structural components with improved mechanical strength and enhanced surface appearance. (C) 2018 Elsevier Ltd. All rights reserved.