Studies on the effect of storage time and plasticizers on the structural variations in thermoplastic starch

• Published in: Carbohydrate polymers Vol. 115; pp. 364 - 372
• Main Authors: Schmitt, H., Guidez, A., Prashantha, K., Soulestin, J., Lacrampe, M.F., Krawczak, P.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 22.01.2015; Elsevier
• Subjects: Ageing; Chemical Sciences; Ethanolamine - chemistry; Glycerol - chemistry; Kinetics; Mechanical Phenomena; Mechanical properties; Plasticized starch; Plasticizers - chemistry; Plastics - chemistry; Polymers; Retrogradation; Sorbitol - chemistry; Starch - chemistry; Structure; Time Factors; Urea - chemistry; Mechanical properties; Plasticized starch; Structure; Ageing; Retrogradation
• ISSN: 0144-8617; 1879-1344
• DOI: 10.1016/j.carbpol.2014.09.004

•We examine the effect of storage time and plasticizers on the structural stability of melt processed thermoplastic starch.•Crystalline type and degree of crystallinity on the plasticizer composition and storage time.•Tensile properties also highly dependent on the plasticizer composition and storage time.•Through different plasticizers and structure- properties can be tuned to meet the requirements of a wide range of applications. Starch was combined with plasticizers such as glycerol, sorbitol, glycerol/sorbitol and urea/ethanolamine blends by means of high shear extrusion process to prepare thermoplastic starch (TPS). Effect of storage time and plasticizers on the structural stability of melt processed TPS was investigated. Morphological observation, X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy reveal that melt extrusion process is efficient in transforming granular starch into a plasticized starch for all plasticizer compositions. XRD analysis highlights major changes in the microstructure of plasticized starch, and dependence of crystalline type and degree of crystallinity mainly on the plasticizer composition and storage time. Dynamical mechanical analysis (DMA) yields a decrease of the peak intensity of loss factor with aging time. The effect of ageing on tensile strength also appears to be highly dependent on the plasticizer composition. Thus, through different plasticizer combinations and ageing, starch-based materials with significant differences in tensile properties can be obtained, which may be tuned to meet the requirements of a wide range of applications.