Biodegradation and the dynamic mechanical properties of starch gelatinization in poly(ε-caprolactone)/corn starch blends

Biodegradable polymers have attracted considerable attention because of their use as substitutes for nonbiodegradable polymers in disposable commodity applications. Poly(epsilon-caprolactone) (PCL) was blended with thermoplastic starch prepared from regular corn starch in PCL/starch ratios of 75/25, 50/50, and 25/75 wt %. The effect of corn starch gelatinization on the properties of these blends was assessed by dynamic mechanical thermal analysis, enzymatic degradation, and biodegradation in simulated soil. Increasing the starch content in the blends, storage modulus (E") increased and enhanced the rigidity of the blends compared to pure PCL. The presence of starch decreased the polymer chain mobility and the intensity of the tan 5 peak. These results probably indicate that PCL/starch blends were thermodynamically immiscible. PCL showed no significant reduction in mass after incubation with a-amylase, whereas blends containing corn starch were more susceptible to this enzyme. The biodegradation seen in simulated soil agreed with the findings for degradation by a-amylase and indicated that the latter was a sensitive method for assessing the degradation of PCL/starch blends and the effect of starch gelatinization over a short period of time. (c) 2006 Wiley Periodicals, Inc.