|Carvalho-Piler, Carlos - EMBRAPA-AGRO-RIO-BRAZIL|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: May 4, 2007
Publication Date: May 30, 2007
Citation: Carvalho-Piler, C.W., Onwulata, C.I., Tomasula, P.M. 2007. Thermomechanical properties of compression molded starch and protein blends. (Abstract). 6th International Symposium on Biopolymers & Composites. p. 1-4. Technical Abstract: One result of the rising costs of petroleum-derived plastic resins is increasing demand for biodegradable products. The main problem with using agriculture-derived biodegradable materials, based on blends of protein and starch, is their limited physical properties; such as, poor stress resistance, insufficient plasticity, and ease of fracture when used in fabricated structures. In this study, we investigated the thermal mechanical effects of compression molding on a binary system of whey protein isolate and corn starch, combined in a torque rheometer. Two thermal transitions were observed by Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analyzer (DMA) for pure starch with onset temperatures at 49 and 75°C; no transitions were observed for protein only indicating that protein was completely denatured. For protein and starch blends, the enthalpies of both transitions increased consistently with starch content, indicating retrogradation of converted starch molecules as well as the presence of granular starch remnants. DMA showed that starch decreased storage modulus, resulting in reduced toughness of the compression molded samples. A binary system of starch and protein has competing mechanisms of retrogradation and denaturation which acts to reduce mechanical properties.