Use of eggshell powder as a potential hydrolytic retardant for citric acid-filled thermoplastic starch

In this study, the effects of eggshell powder and citric acid on the properties of thermoplastic starch (TPS) were investigated. All components were melt-blended using an internal mixer. Citric acid led to the formation of crosslinking structures (as shown in the FTIR spectra at 1730 cm(-1)) and caused rapid sample biodegradation with accelerated hydrolysis. Conversely, addition of eggshell powder retarded the biodegradation. After storing the samples for 30 days, CaTPS (Cassava root TPS) without eggshell powder showed erosion over almost the entire surface, while the surface of CaTPS containing 20 phr of eggshell powder (CaTPSES20) remained unchanged. The residual TGA weight at 400 degrees C and the change in carbonate FTIR intensity peak of CaTPSES20 after the storage period provided both quantitative and qualitative evidence that eggshell powder can be considered a potential hydrolytic retardant for citric-acid-filled TPS. (C) 2020 Elsevier B.V. All rights reserved.