The Influence of Polymer Blending on Poly(E-Caprolactone) Degradation

This study was designed to enhance the degradation rate of poly(e- caprolactone) (PCL) via blending with less crystalline low molecular weight PCLs (MW 300, 530 and 900) or hydrophilic polyethylene glycols (MW 600 and MW 3,350). The thermal properties and crystallinities of blends were measured by differential scanning calorimetry. The acid- catalyzed hydrolysis of the blends was conducted in aqueous p-toluenesulfonic acid by measuring weight loss. Incorporation of PCLL into PCL reduced the crystallinity of the polymers to 45-58%, which depended on the weight ratio of PCLL in blends. All blends showed two degradation phases, a rapid initial weight loss during the first 5 days indicating the loss of PCLL followed by a slow decline in weight corresponding to the loss of PCL. The slope of the second phase was approximately the same as that observed for pure PCL. These results indicated that PCL and PCLL degraded separately in the blends. The incorporation of PEG 600 into PCL only slightly reduced polymer crystallinity. However, PCL and PEG 3,350 were separately crystallized in the blends. The biphasic weight loss behavior was also present in PCL-PEG blends, where the PEG domain in blends leached out rapidly during the first few days resulting in micropores in the matrix