Influence of the content of corn thermoplastic starches (TPS) prepared with different plasticizers on the rheological and mechanical properties of PCL/TPS blends

• Published in: Polymer bulletin (Berlin, Germany) Vol. 80; no. 7; pp. 7627 - 7640
• Main Authors: Marinho, Vithória A. D., Sousa, Fernanda M., Vinhas, Glória M., Almeida, Yeda Medeiros B., Carvalho, Laura H.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.07.2023; Springer Nature B.V
• Subjects: Babassu oil; Biodegradable materials; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Complex Fluids and Microfluidics; Elongation; Fatty acids; Mechanical properties; Organic Chemistry; Original Paper; Physical Chemistry; Polycaprolactone; Polymer blends; Polymer Sciences; Rheological properties; Rheology; Soft and Granular Matter; Starches; Thermal degradation; Vegetable oils; Viscosity; Thermoplastic starch (TPS); Mechanical properties; Plasticizer; Polycaprolactone (PCL); Rheological properties
• ISSN: 0170-0839; 1436-2449
• DOI: 10.1007/s00289-022-04416-7

Preparing blends from fully biodegradable resources is an important alternative in the production of materials less harmful to the environment. Among these materials, thermoplastic cornstarch (TPS) and polycaprolactone (PCL) are an interesting possibility for replacing conventional synthetic materials, and it is desirable that they present relative stability under conditions of processing and use. In the present work, PCL/TPS blends with up to 30% TPS, obtained from cornstarch plasticized with water and glycerin, coconut or babassu oil, were processed in an internal laboratory mixer. Adjusted torque variation rate during the last processing stage is a very sensitive indicator of molar mass alterations with processing time. Rheometry data indicate that TPS obtained with babassu and coconut vegetable oils have a higher molar mass compared to that obtained with glycerin. In addition, the incorporation of TPS promotes thermal degradation in PCL/TPS mixtures, which is more pronounced the higher the TPS content and with TPS-glycerin, except for the PCL/20%TPS blends obtained with glycerin and babassu oil. The mechanical properties of the extruded films decreased with the addition of TPS, this reduction being more evident with the increase in the TPS content and in systems with TPS obtained with babassu oil. In contrast, only in blends containing 10 and 20% TPS of glycerin, there was an increase in elongation at break, being a good feature for flexible films, this property is desirable in certain applications.