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Preparation and properties of biodegradable poly(butylene succinate)/starch blends



The vital differences between the use of untreated starch and gelatinized starch in blends with poly(butylene succinate) (Bionolle) were thoroughly examined in this study. The melting temperature decreased slightly with increasing dosages of untreated and gelatinized starch. The added starch perhaps tended to disrupt the intermolecular hydrogen bonding within the Bionolle matrix. On the other hand, a large increase in the crystallinity was seen with the addition of starch. Starch appeared to play a nucleating role in the blends. The trend of the glass-transition temperature decreasing with the starch level was similar to the trend of the melting temperature. For the same starch content, the glass-transition temperature showed some variations. For blends containing a certain amount of gelatinized starch, the thermal stability remained to a certain degree but continued to decrease. This was ascribed to the relatively low heat stability of starch. As for the mechanical properties, a significant increase in the tensile strength (up to 2 times) was observed when untreated starch was replaced with gelatinized starch in the blends. Similarly, the tear strength increased up to 1.5 times if gelatinized starch was employed. Apparently, the gelatinization of starch was efficiently achieved for promoting its compatibility with Bionolle. In all cases, the mechanical properties of Bionolle blended with gelatinized starch were better than those of Bionolle blended with untreated starch. A morphological investigation provided evidence in support of these findings. This relatively low-cost gelatinization approach provides an alternative to a high-cost compatibilizer approach for improving the performance of biodegradable blends. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 257–264, 2005