Abstract
We investigated the shape-recovery characteristics of thermoplastic polyurethane (TPU) with a microcellular foaming process (MCP). Additionally, we investigated the correlation between changes in the microstructure and the shape-recovery characteristics of the polymers. TPU was selected as the base material, and the shape-recovery characteristics were confirmed using a universal testing machine, by manufacturing dog-bone-type injection-molded specimens. TPUs are reticular polymers with both soft and hard segments. In this study, we investigated the shape-memory mechanism of foamed polymers by maximizing the shape-memory properties of these polymers through a physical foaming process. Toward this end, TPU specimens were prepared by varying the gas pressure, foaming temperature, and type of foaming gas in the batch MCP. The effects of internal structural changes were investigated. These experimental variables affected the microstructure and shape-recovery characteristics of the foamed polymer. The generated cell density changed, which affected the shape-recovery characteristics. In general, a higher cell density corresponded to a higher shape-recovery ratio.
Highlights
The objective of this study was to investigate the changes in the shape-memory-recovery characteristics of thermoplastic polyurethane (TPU), with changes in the microstructure by employing a microcellular foaming process (MCP), which is a physical foaming process [1–4]
The MCP, which is applied to TPU as a matrix, is a method for producing microsized cells having a density of
In a pressure vessel at a high temperature and high pressure, the outside of the polymer plastic was under a relatively high pressure compared with the inside
Summary
The objective of this study was to investigate the changes in the shape-memory-recovery characteristics of thermoplastic polyurethane (TPU), with changes in the microstructure by employing a microcellular foaming process (MCP), which is a physical foaming process [1–4]. The MCP, which is applied to TPU as a matrix, is a method for producing microsized cells having a density of. >109 cells/cm within 10 μm inside polymer plastics. This method was recently applied to the production of advanced electronic products [5]. The plastic-manufacturing method with fine cells has several advantages, such as reduced production time, reduced product weight, reduced material cost, minimized post-transformation, insulation, and soundproofing. In a pressure vessel at a high temperature and high pressure, the outside of the polymer plastic was under a relatively high pressure compared with the inside
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