Thermal and mechanical properties of biodegradable nanocomposites prepared by poly(lactic acid)/acetyl tributyl citrate reinforced with attapulgite

Attapulgite (ATT) is a multi-purpose nanomaterial, which can be used as a reinforcing filler for polylactic acid (PLA) and improve its barrier performance. However, due to the high content of ATT, it is easy to cause agglomeration. In this study, acetyl tributyl citrate (ATBC) was used to improve the toughness of PLA, and the plasticizer could reduce the polymer viscosity and improve the processability, which may contribute to the dispersion of ATT in PLA. The results show that a small amount of ATBC can improve the fracture elongation, crystallinity, water absorption, hydrolysis, and biodegradability of PLA. On the other hand, when ATT is added to PLA/ATBC sample by 10%, the tensile strength, and thermal degradation temperature can be greatly improved and reach the maximum value. Compared with pure PLA, the tensile strength is significantly increased by 33.4% (60.3 MPa), the elongation at break increased by 177.56%, and the thermal degradation temperature increased significantly by about 20.1 ℃. According to the scanning electron microscope and energy dispersive spectrometer, when ATT ≤ 10%, the nanofiller has excellent dispersion in the matrix, but when ATT > 10%, the nanofiller appears serious agglomeration and interfacial phase separation, which is caused by the incompatibility between PLA and ATT, so the performance of the nano composite is greatly reduced. From the results of soil burial and hydrolysis tests, the weight loss rate of PLA/ATBC samples increased with the increase of ATT nanofiller content. The influence of the internal and external tightness of the sample structure on the biodegradability was explained from the analysis results of water absorption and contact angle. The synergy of ATT and ATBC improves the comprehensive performance of PLA and increases its feasibility as a packaging material.