Enhanced nonisothermal and isothermal cold crystallization kinetics of biodegradable poly(L-lactide) by trisilanolisobutyl-polyhedral oligomeric silsesquioxanes in their nanocomposites

In this work, the nonisothermal and isothermal cold crystallization behaviors of poly(L-lactide) (PLLA)/trisilanolisobutylpolyhedral oligomeric silsesquioxanes (tsib-POSS) nanocomposites with low tsib-POSS contents were fully investigated. For all the samples, the variations of heating rate and the tsib-POSS loading may influence the nonisothermal cold crystallization of PLLA. During the nonisothermal crystallization kinetics study, the Ozawa equation failed to fit the nonisothermal crystallization process of PLLA, while the Tobin equation could fit it well. For the isothermal crystallization kinetics study, the crystallization rates of all the samples increased with increasing crystallization temperature. The cold crystallization activation energy of PLLA was increased with 1 wt % tsib-POSS. Moreover, the addition of tsib-POSS and the increment of tsib-POSS loading could increase the crystallization rate of PLLA, indicating the nucleating agent effect of tsib-POSS. However, the crystallization mechanism and crystal structure of PLLA remained unchanged in the nanocomposites. (C) 2016 Wiley Periodicals, Inc.