Effects of divinylbenzene-maleic anhydride copolymer hollow microspheres on crystallization behaviors, mechanical properties and heat resistance of poly(l-lactide acid)

Divinylbenzene-maleic anhydride copolymer hollow microspheres (DMs) were used as novel organic nucleating agents to promote crystallization of poly(l-lactide acid) (PLLA). The effects of these DMs on crystal behaviors of the PLLA were investigated by differential scanning calorimeter (DSC), polarizing optical microscopy (POM), and wide angle X-ray diffraction (WAXD). Both isothermal and non-isothermal processes in DSC demonstrated that the DMs significantly altered the crystal behaviors of PLLA as both crystallization velocity and degree of crystallinity increased with increasing DM loadings from 0 to 3%. Our POM results also indicated that as nucleating agents, the DMs promoted nucleating densities and decreased spherulitic sizes. In addition, WAXD suggeted that the addition of DMs did not induce new types of crystals. Finally, our results showed that the ductility of the PLLA was enhanced by a small amount of DMs during the PLLA crystallization process since 0.5% DMs added to the PLLA resulted in 1.4-fold increase in the elongation at break in comparision with the neat PLLA.