Gas/Supercritical Fluid Injected Micro-/Nano-Layer Coextrusion Foam Processes

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Most new advanced polymeric products in the automotive, aerospace, biomedical, and food and electronics packaging industries contain two or more polymers and functional additives resulting in desired properties contributed from each component. The coextrusion process extrudes multiple materials simultaneously in a one-step process to form a multilayer structure for unique applications. Foams can be prepared from any plastic by introducing a gas or supercritical fluid (SCF) within the plastic during processing. Current foam processes are unable to produce high-performance foams with ultra low-density, uniform nano-sized cells and/or gradient cell size distributions. We propose a new micro-/nano-layer (MNL) coextrusion foam process technology to create the synergistic effects between two processes (i.e., MNL coextrusion and foaming). With in-depth understanding of gas/SCF concentration-dependent microstructure and cell structure evolutions, this technology will enable manufacturing of high-performance composite foams with tailored properties. This Discovery program focuses on developing and applying the MNL coextrusion foam platform, the first for Canada, to provide fundamental understanding of the manufacture of multiphase nano-structured composite foam materials with tailored properties. Aim 1 will provide the first data set quantifying crystal nucleation, growth, and lamellae orientation under a high-pressure gas/SCF in nano-layered structures, where such data are simply not available. Aim 2 will employ the MNL coextrusion foam platform with a direct gas/SCF injection capability to produce well-controlled low-density, nano-cellular composite foams, which is not currently available. Aim 3 will address gas/SCF sorption and desorption behaviours under both static and dynamic conditions. The dynamic data (i.e., under shear and extensional stresses) are more relevant to real foam processes and are lacking, thus showing a critical need to measure these properties accurately under more process-relevant conditions to understand microstructure and cell morphology evolutions with respect to gas concentration. Collectively, these three aims will enable manufacturing of well-engineered high-performance composite foam materials. The technological impact of this proposed program on the existing state of knowledge within the polymer and composites engineering and processing community is expected to be significant. In particular, the results will benefit Canadian companies manufacturing value-added plastic materials. Moreover, this interdisciplinary program, which encompasses manufacturing, polymer chemistry, polymer physics and materials science, will provide participating highly qualified personnel (HQP) with unparalleled training experience, helping them to acquire scientific knowledge, practical experience and soft skills, and to establish a professional network that will advance their careers in many disciplines.