Effect of low octavinyl-polyhedral oligomeric silsesquioxanes loadings on the melt crystallization and morphology of biodegradable poly(l-lactide)

Biodegradable poly(l-lactide) (PLLA)/octavinyl-polyhedral oligomeric silsesquioxanes (ovi-POSS) nanocomposites were prepared via solution and casting method at low loadings of ovi-POSS in this work. Effect of ovi-POSS on the crystallization behavior, spherulitic morphology, crystal structure, and thermal stability of PLLA in the nanocomposites was investigated in detail. It is found that both nonisothermal melt and cold crystallization of PLLA in the nanocomposites are enhanced by the presence of ovi-POSS. In addition, the enhancement becomes more significant with the increase of POSS content to 1 wt%. For isothermal melt crystallization, the overall crystallization rates are faster in the PLLA/ovi-POSS nanocomposites than those in neat PLLA and improved with increasing the ovi-POSS loading; however, the crystallization mechanism and crystal structure of PLLA remain unchanged despite the presence of ovi-POSS. The thermal stability of PLLA in the PLLA/ovi-POSS nanocomposites is reduced slightly relative to neat PLLA.