Morphologies of transverse sections of the ternary composites including of PLA, ESO and cellulosic fillers are presented in Fig. 2. Many gaps and clear interfaces are observed between MCC and PLA in PLA/MCC/ESO composite (see Fig. 2(a)). It reflects the poor interfacial adhesion. After using MA modified MCC in ternary com- posites, the rupture interface gradually becomes obscure (see Fig. 2(b)–(d). This result exhibits that the interfacial adhesion can be improved by the surface modification of MCC.