Fully Biobased Shape Memory Thermoplastic Vulcanizates from Poly(Lactic Acid) and Modified Natural Eucommia Ulmoides Gum with Co-Continuous Structure and Super Toughness

Abstract

Novel, fully biobased shape memory thermoplastic vulcanizates (TPVs) were prepared using two sustainable biopolymers, poly(lactic acid) (PLA), and modified natural Eucommia ulmoides gum (EUG-g-GMA), via a dynamic vulcanization technique. Simultaneously, in situ compatibilization was achieved in the TPVs to improve interfacial adhesion and the crosslinked modified Eucommia ulmoides gum (EUG) was in “netlike” continuous state in the PLA matrix to form “sea-sea” phase structure. The promoted interface and co-continuous structure played critical roles in enhancing shape memory capacity and toughness of the TPVs. The TPV with 40 wt % modified EUG displayed the highest toughness with an impact strength of 54.8 kJ/m2 and the most excellent shape memory performances with a shape fixity ratio (Rf) of 99.83% and a shape recovery ratio (Rr) of 93.74%. The prepared shape memory TPVs would open up great potential applications in biobased shape memory materials for smart medical devices.

Covalent crosslinks turn natural Eucommia ulmoides gum/polybutene‐1 composites into multiple shape memory materials

“…This increase can be ascribed to the increase in cross‐linking density, and the latter was further evidenced by swelling measurement results (Figure 2B). Based on the aforementioned results as well as our previous findings, [ 10,23,35 ] the formation of covalent cross‐linking networks in the EUG/PB‐1 composites are schematically shown in Figure 2C. As the initiating reaction, DCP was decomposed into free radicals, which attacked EUG and PB‐1 molecules at 170°C leading to the formation of macromolecular free radicals.…”

“…As can be seen from Table 4, covalent crosslinks lowered both deformation rate (4ε) and shape fixing ratio (R f ), whereas shape recovery ratio (R r ) was increased obviously with increasing DCP content. Such a phenomenon could be explained by one fact that storage moduli of the composites were increased with increasing DCP content leading to declined deformation capacity and increased shape recovery ability [10,16] and the other that more EUG and PB-1 crystals served as reversible domain were suffered in the composite crosslinked by more DCP resulting in decreased shape fixing capability. [37] Given that two well-separated crystalline and melting phase transitions were present in the crosslinked EUG/PB-1 composites, triple shape memory behavior was expected and analyzed in the present study.…”

“…[3,7,8] In general, the original shape of SMPs is manipulated during processing while temporary shapes are programmed under certain external conditions. [9,10] The heat-triggered SMPs (HSMPs) have been paid much attention in the past decades and experienced explosive advances recently, [2,[11][12][13] involving novel strategies to fabricate SMPs with multiple stimulus, degradable and biocompatible SMPs, and enhancement of SMPs, [14,15] and so forth. However, it is still quite challenging to prepare HSMPs with multiple shape memory effects (SME) realized through several phase transitions or broadened glass transition via chemical synthesis, which limits its further development.…”

Natural Polymer Eucommia Ulmoides Rubber: A Novel Material

“…167 Fully biobased shape memory thermoplastic vulcanizates (TPVs) were prepared by using poly(lactic acid) (PLA) and modified EUR (EUR-g-GMA) via a dynamic vulcanization technique. 143 The TPV with 40% modified EUR displayed the highest toughness with an impact strength of 54.8 kJ/m 2 and the most excellent shape memory performance with a shape fixity ratio (R f ) of 99.83% and a shape recovery ratio (R r ) of 93.74%. These prepared TPVs would open up great potential application in biobased shape memory materials for smart medical devices.…”

Research progress on toughening and modification of polylactic acid with environmentally friendly materials

“…Wang等 [29] 图 5 衣康酸甲酯(a)及其改性环氧化玉米油(b)的合成路线 图 [33] (网络版彩图) 图 6 CNCaq-rD和CNCaq-rD-PDLA两种增韧改性剂的合成 路线 [36] (网络版彩图) Figure 6 Synthetic routes of CNCaq-rD and CNCaq-rD-PDLA two toughening modifiers [36] [37] (网络版彩图) 图 8 酯化淀粉颗粒(a)和核壳结构淀粉纳米粒子(b)的制备示意图 [40] (网络版彩图)…”