PHBHHx/PDLLA 摻合電紡膜之鑑定與降解行為

Abstract

Blends of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) and poly(D, L-lactic acid) (PDLLA) in different ratios were fabricated into fibrous membranes by electrospinning processes. PHBHHx and PDLLA kept individual glass transition temperatures in the blend system and the melting point of PHBHHx didn’t shift with the added PDLLA indicated that the blend system was immiscible. The crystal size measured by WAXD and the long period estimated by SAXS were kept the same in the blends. The enthalpy of fusion and the PHBHHx content of the blends were linearly correlated. Therefore, it can be concluded that PDLLA in the blend system didn’t affect the growth of PHBHHx crystalline phase and PDLLA was excluded from PHBHHx lamella stack. The electrospun fibrous membranes of the blends only had two diffraction peaks due to the oriented chain packing in the crystalline phase in the fibers, and the intensity of those two peaks decreased as the amorphous PDLLA increased. The mechanical properties of the electrospun fibrous membranes depended on the orientation of fibers and the porosity in the membranes. The electrospun membranes had higher elongation, and the individual electrospun fibers were stronger and stiffer than the corresponding cast membranes. As the content of PDLLA increased, the electrospun fibrous membranes of the blends showed higher elongation and lower elastic modulus. The hydrolytic degradation of the electrospun fibrous blends observed by SEM indicated that the PHBHHx portion proceeded surface erosion and the PDLLA portion was characterized by bulk erosion. After 24-week degradation, the mass loss of the fibrous blends was less than 3 %. The molecular weight lowered and the PDI was raised with degradation time.