Morphology, Crystallization Behavior, and Dynamic Mechanical Properties of Biodegradable Poly(ε-caprolactone)/Thermally Reduced Graphene Nanocomposites

Biodegradable poly(epsilon-caprolactone) (PCL)/thermally reduced graphene (TRG) nanocomposites were prepared via a solution mixing method at low TRG loadings in this work. Transmission electron microscopy and high resolution transmission electron microscopy observations reveal that a fine dispersion of TRG has been achieved throughout the PCL matrix. Scanning electron microscopy observation shows not only a nice dispersion of TRG but also a strong interfacial adhesion between TRG and the matrix, as evidenced by the presence of some TRG nanosheets embedded in the matrix. Nonisothermal melt crystallization behavior, isothermal melt crystallization kinetics, spherulitic morphology, and crystal structure of neat PCL and the PCL/TRG nanocomposites were studied in detail with various techniques. The experimental results indicate that both nonisothermal and isothermal melt crystallization of PCL have been enhanced significantly by the presence of TRG in the nanocomposites due to the heterogeneous nucleation effect; however, the crystallization mechanism and crystal structure of PCL do not change. Dynamic mechanical analysis study shows that the storage modulus of the nanocomposites has been greatly improved by about 203% and 292%, respectively, with incorporating only 0.5 and 2.0 wt % TRG at -80 degrees C as compared with neat PCL.