Abstract
Poly(l-lactic acid) (PLA)/epoxy vinyl polyhedral oligomeric silsesquioxane (EP-POSS) nanocomposites were prepared via melt blending. The isothermal cold crystallization and melting behavors of pure PLA and its nanocomposites were investigated using differential scanning calorimetry (DSC). The crystal growth model of PLA was a mixture of two-dimensional discotic growth and three-dimensional spherulite growth, as evidenced by the values of the Avrami exponent ranging from 2.15 to 2.66. The crystallization rate displayed a great dependence on the EP-POSS loading level and crystallization temperature, and a transition from regime II to regime III was observed around 115°C. The values of fold surface free energy were calculated from the nucleation parameter which was determined by the Hoffman-Lauritzen equation. Polarizing microscope images (POM) indicated that EP-POSS promoted the nucleation of PLA.
Notes
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