Preparation,Structure And Properties Of Binary And Ternary Poly(Ethylene Adipate)/Graphene Oxide Nanocomposites

This work adopts two methods to synthesize PEA/GO binary composites and PLLA/PEA/GO ternary composites respectively after using modified Staudenmaier method to prepare graphene oxide (GO). Tensile test, SEM, TGA and a series of characterization methods were used to study the variation of crystallization behavior, mechanical performance and other properties of PEA binary and ternary nanocomposites.Firstly, A series of graphene oxide (GO) incorporated poly(ethylene adipate)(PEA) nanocomposites were prepared at low GO loadings using a solution and precipitation method, with GO content of0.1,0.5and1.0wt%, respectively. SEM observation showed a fine dispersion of GO with layered structure throughout the PEA matrix. Compare to neat PEA, GO greatly enhanced the nonisothermal crystallization behavior and isothermal melt crystallization kinetics due to the nucleation effect of GO. However, the crystal mechanism and structure remained unchanged. Researches on spherulites morphology further proved this kind of heterogeneous nucleation effect of GO. At the same time, neat PEA and its nanocomposites were both observed to have typical banded spherulites within the research temperature range. What’s more, the addition of GO was also found to widen the temperature range of banded spherulites formation. Through the measurement of spherulites growth rate, it was interesting to find that GO not only enhanced the nucleation density as a nucleating agent but also increased the spherulitic growth rate of PEA.Secondly, the binary and ternary blending materials or composites-PLLA/PEA, PLLA/GO, PLLA/PEA/GO as well as neat PLLA were successfully prepared through solution evaporation method. The PLLA to PEA ratio is85:15while the content of GO is0.5wt%. SEM characterization result reveals that PLLA and PEA are mutually miscible and the addition of PEA has PLLA presented a relatively rough appearance. In PLLA/PEA/GO ternary nanocomposite, a homogeneously distributed GO existing as exfoliated single layers in matrix was observed. Both GO and PEA facilitate isothermal and nonisothermal crystallization of PLLA in which the facilitation effect of GO is greater than that of PEA. However, the addition of both GO and PEA didn’t change the crystallization structure of PLLA. In further spherulites morphology study, PEA greatly enhanced the spherulites growth rate of blending materials and ternary composites as plasticizer, while GO functioned as nucleation agent and had no evident effect on spherulites growth rate. It is found in the measurement of thermal stability that GO and PEA had no apparent influence on DTG peak temperature of the material but changed the initial degradation temperature obviously. In mechanical performance test, PLLA/PEA/GO showed better performance than neat samples in tensile and dynamic mechanics tests, especially that the addition of PEA changed the fracture of PLLA from fragile to ductile while the presence of GO exempted the composites from the relatively large loss of stretching stress and Young’s modulus.