Modification of the Properties of Polylactide/ Polycaprolactone Blends by Incorporation of Blocked Polyisocyanate

Abstract

This work investigates and discusses the thermal, mechanical, thermo-mechanical properties and the morphology of solvent cast products from polylactide (PLA) and polycaprolactone (PCL), as well as their blends containing ethyl cellosolve blocked polyisocyanate (EC-bp), which was introduced as a crosslinker. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) are used to analyze the effects of the addition of EC-bp and PCL on the thermal and crystallization behaviors. The results show that the glass transition temperature (T_g) and crystallization rate is increased and decreased by the addition of EC-bp, respectively, whereas the opposite tendency is observed in the presence of PCL. Tensile testing shows much better tensile properties of the EC-bp modified blends in comparison with unmodified ones. Dynamic mechanical analysis (DMA) reveals that the storage modulus and thermal stability of the PLA/PCL blends with EC-bp are enhanced with respect to the ones without. Environmental scanning electron microscopy (ESEM) is used to characterize the morphology and evaluate the interfacial adhesion. The result demonstrates that much better dispersion (PCL domains) and homogeneity morphology is achieved for EC-bp modified blends, which indicates that the addition of EC-bp can improve the interfacial adhesion.

Keywords:

• Biomaterials
• blends
• mechanical properties
• thermal behaviors
• morphology

Acknowledgment

This work was supported by the National High Technology Research and Development Program of China (863 plan) (Grant No. 2007AA100704).