The role of foaming process on shape memory behavior of polylactic acid-thermoplastic polyurethane-nano cellulose bio-nanocomposites.

In this study the effects of foaming process on the shape memory properties of Polylactic acid/thermoplastic polyurethane/cellulous-nanofiber bio-nanocomposites were investigated. The samples of cylindrical shapes as well as sheets were manufactured and foamed. The results indicated that while the foaming process presented a microcellular structure, it can cause a tangible increase (up to 40%) in force recovery ratio and an intense reduction (up to 10 times) in actuation force. It is statistically shown that the existence of cellulose nano-fibers within the foamed matrix causes a significant increase in actuation force and reduction in the force recovery ratio. Analytical evaluation on the sheet form samples, in the foamed state using rheological model, was carried out that indicated satisfying description of their shape memory behaviors. It was also demonstrated that there exists significant deviation between the shape memory properties extracted from experimental and analytical assessments.