Influence of Reaction-Induced Microphase-Separation Structure on Mechanical Properties, Shape Memory, and Recyclable Performance of EVA–Polyurea Nanocomposite

The interfacial interaction and microstructure of polymer nanocomposites strongly affect their performance. Here, the unique interfacial interaction and microphase separation structure were formed during the process of preparing ethylene-vinyl acetate copolymer/polyurea (EVA–PUA) nanocomposites by a reaction-induced microphase-separation structure. FTIR, DMA, and AFM measurements were used to study the interfacial interaction between EVA and PUA and the morphology of EVA–PUA nanocomposites, respectively. Compared with the EVA/PUA blend prepared by melt mixing, this method endows the materials with excellent properties, including enhanced strength and recyclable performance. Compared to pure EVA, the stiffness and toughness of the EVA–PUA nanocomposite were dramatically improved simultaneously. The tensile strength increased by 47%, and the toughness improved by 36.3%. Such effects are difficult to realize in EVA samples with dynamic cross-linking bonding. The reason that the reaction-induced microphase separation can dramatically promote the performance of EVA–PUA nanocomposites was found. The above results demonstrate a general strategy for fabricating elastomer nanocomposites that overcome the traditional trade-offs between stiffness and toughness. More interestingly, this nanocomposite presented good shape- memory performance. EVA–PUA nanocomposites presented excellent recyclable performance, and the recycled EVA–PUA nanocomposites maintained their mechanical properties well.