Preparation, thermal degradation, and rheology studies for polylactic acid (PLA) and palm stearin (PS) blend: A review

Abstract

In various types of applications, poly(lactic acid) (PLA) might be considered one of the potential alternatives to petrochemical-derived polymers such as polypropylene. However, PLA's disadvantages, such as its brittleness, heat characteristics, and degrading stability, restrict its use. To improve the aforementioned PLA qualities, polymerization, plasticization, and PLA blends are all being investigated. This research examines the production of PLA using various bio-based plasticizers to enhance the qualities of PLA, such as satisfying industrial requirements and recognising the limitations of each modification. Due to favourable results from other palm oil-based plasticizers described in various polymer modification works, palm stearin is a new candidate considered to be a strong option as a plasticizer to overcome the limits of PLA. Palm stearin is a co-product of palm olein and, it is always traded at a discount to palm oil and palm olein. Considering PLA and palm stearin are potentially prepared by melt-blending, the thermal properties such as glass transition temperature (Tg), cold crystallization temperature (Tcc), and the melting temperature (Tm) are critical to be investigated further for this blend because of the partial crystallization properties of palm stearin, which are characterized by differential scanning calorimetry (DSC) under a nitrogen atmosphere. Characterizations such as torque, rheology, and Fourier Transform Infrared Spectroscopy (FTIR) were also reviewed on the plasticized PLA to study the compatibility and the biodegradable of this plasticized PLA. From this review, a suitable processing design for PLA and palm stearin blend was determined, and the thermal and rheology characteristics for PLA and the bio-plasticizer were successfully reviewed.