Fully Biobased Shape Memory Material Based on Novel Cocontinuous Structure in Poly(Lactic Acid)/Natural Rubber TPVs Fabricated via Peroxide-Induced Dynamic Vulcanization and in Situ Interfacial Compatibilization

Abstract

Shape memory polymers (SMPs) based on fully biobased poly(lactide) (PLA)/natural rubber (NR) thermoplastic vulcanizates (TPVs) were fabricated via peroxide-induced dynamic vulcanization. Simultaneously, in situ reactive compatibilization was achieved by PLA molecule grafting onto NR chains. Differing from the general concept of spherical rubber particles being formed after dynamic vulcanization, the cross-linked NR was found to be a "netlike" continuous phase in the PLA matrix. This novel structure explained the surprising shape memory property of PLA/NR TPVs well (shape fixities ∼ 100%, shape recoveries > 95%, and fast recovery speed < 15 s at the switching temperature, ∼60 °C): the cross-linked NR continuous phase offers strong resilience and the PLA phase serves as the heat-control switch. We envision that the "green" raw materials and excellent shape memory properties of the dynamically vulcanized PLA/NR SMPs will open up a wide range of potential applications in intelligent medical devices.

Bio‐based thermoplastic polyurethane and polyamide 11 bioalloys with excellent shape memory behavior

“…In case of PA‐20%, the TPU phase (matrix) has shown slight effect on shape fixity, it has shown an average shape fixity of 85%. This is due to the fact that, generally, in a traditional heat‐triggered shape memory polymers based on cross linked network, a certain fraction of the stretched chains or chain segments (usually the soft segment) still preserved mobility in the cooling stage, hence generating an instantaneous retract without the tensile loading and therefore decrease the shape fixity. But the sample showed recovery ratios over 90% during three thermo mechanical cycles.…”

Fully bio-based, highly toughened and heat-resistant poly(L-lactide) ternary blends via dynamic vulcanization with poly(D-lactide) and unsaturated bioelastomer

“…Therefore, specific compatibilization is required to fine-tune the morphology and enhance the interfacial adhesion between PLLA and the blending partners [17,18]. Dynamic vulcanization, involving selective crosslinking of rubber polymer during melt blending with a thermoplastic polymer, has been demonstrated to be a powerful technique to control the morphology, enhance interfacial adhesion, and improve the final properties of PLLA blends with elastic polymers [19][20][21][22][23]. Some supertough PLLA blends with impact strengths of more than 530 J m −1 (or 53 kJ m −2 ) have been achieved by dynamic vulcanization of PLLA with some elastic polymers [22,[24][25][26][27][28].…”

Improvements in mechanical strength and thermal stability of injection and compression molded components based on Poly Lactic Acids

“…[1] In this way, intervening on the structure and morphology of the resulting blends (formation of dispersed phases structures [2][3][4][5][6][7][8] or interconnected and co-continuous structures [9][10][11][12] ); it is possible to obtain materials boasting higher mechanical strength and ductility. On the other hand, PLA shows a molten phase that is not thermally resistant during conventional | 2159 AVERSA Et Al.…”