Thermal Properties of Poly(L- lactide)/Poly(ethylene glycol) Blends Based on Different Poly(ethylene glycol) Molecular Weights

摘要

Due to the feasibility of their tailor-made properties, polymer blends continue to attract much attention both academically and industrially. Hence, investigations on various polymer blends have been conducted.[1] As it is known, the properties of the final blend product indeed depend on the miscibility between components. For crystalline polymer blends, their crystallization kinetics plays a major role on the resultant properties as well. Of all the crystalline blend systems investigated, studying the miscibility and physical properties of poly(L-lactide) (PLLA)-based blends has been among the major concerns.[2-11] PLLA is a well-known biodegradable and biocompatible thermoplastic. From an ecological viewpoint, the versatility of PLLA has to be enhanced. Poly(ethylene glycol) (PEG) has served as a counterpart for modifying PLLA. Since both PLLA and PEG are able to crystallize, studies on the miscibility, crystallization kinetics, and phase morphology of PLLA/PEG blends are essential. Younes and Cohn[8] investigated the PLLA/PEG blends with various PEG molecular weights (MWs). Based on the melting temperature (Tm) depressions of both PLLA and PEG, they concluded that the blends indeed exhibit certain phase mixing features. The fact that the microphase separation occurred in the blends was generated by the crystallization(s) of the component(s). Nakafuku and his colleague[9,10] studied the crystallization, melting, and crystalline morphology of PLLA/PEG blends. Partial miscibility between PLLA and PEG molecules was