Influence of incorporation of starch nanoparticles in PBAT/TPS composite films

Films of PBAT/TPS (poly(butylene adipate-co-terephthalate)/thermoplastic starch) (starch plasticized with glycerol containing citric and stearic acids) without and with 0.6 wt% starch nanoparticles were produced by extrusion. The presence of nanoparticles during the extrusion process led to a higher degree of starch gelatinization improving starch compatibility with PBAT. Nanoparticles modified the interaction between the different components of the PBAT/TPS composite. The hydroxyl groups of the starch nanoparticles interacted with starch amylose by means of hydrogen bonds. In addition, nanoparticles modified the structure of the PBAT rigid segment (BT): a shift of T-m of BT toward lower temperatures and a slight shift of the relaxation of the BT segment to higher temperatures were observed. The incorporation of nanoparticles also had a reinforcing effect on the PBAT/TPS matrix. The composite presented slight increases of Young's modulus (E) and stress at break (sigma(b)) without affecting the strain at break (E-b). The rate of biodegradability was improved with the use of starch nanoparticles. The composite showed faster deterioration than the matrix, showing the first changes in its tonality and breakdowns at only 6 days of burial in compost. (c) 2016 Society of Chemical Industry