Toward Environment-Friendly Composites of Poly( e-caprolactone) Reinforced with Stereocomplex-Type Poly( L-lactide)/Poly( D-lactide)

In this work, stereocomplex-poly(l- and d-lactide) (sc-PLA) was incorporated into poly(epsilon-caprolactone) (PCL) to fabricate a novel biodegradable polymer composite. PCL/sc-PLA composites were prepared by solution casting at sc-PLA loadings of 5-30 wt %. Differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD) demonstrated the formation of the stereocomplex in the blends. DSC and WAXD curves also indicated that the addition of sc-PLA did not alter the crystal structure of PCL. Rheology and mechanical properties of neat PCL and the PCL/sc-PLA composites were investigated in detail. Rheological measurements indicated that the composites exhibited evident solid-like response in the low frequency region as the sc-PLA loadings reached up to 20 wt %. Moreover, the long-range motion of PCL chains was highly restrained. Dynamic mechanical analysis showed that the storage modulus (E) of PCL in the composites was improved and the glass transition temperature values were hardly changed after the addition of sc-PLA. Tensile tests showed that the Young's modulus, and yield strength of the composites were enhanced by the addition of sc-PLA while the tensile strength and elongation at break were reduced. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40208.