Cardanol derivatives as innovative bio-plasticizers for poly-(lactic acid)

Abstract

This work is aimed to study the suitability of a bio based compound, cardanol acetate (CA), as plasticizing agent of poly(lactic acid) (PLA). Compared to other natural derived plasticizers, cardanol acetate is not obtained from food crops but as a by product of cashew nut extraction. In addition, the cardanol derived plasticizers can be obtained by the use of non toxic and low environmental impact reagents. The plasticizing effectiveness of cardanol acetate was confirmed by the decrease of the glass transition temperature and flexural modulus, which were comparable to those obtained by the use of conventional oil based plasticizers, such as diethylhexyl phthalate (DEHP). In addition, calorimetric analysis revealed that the addition of the plasticizer, both cardanol derived and phthalate, involves a significant increase of the crystallization kinetics. An analysis of the flexural strength and deformation at break indicated that the increase of the crystallization kinetics has more dramatic effects compared to the decrease of the glass transition, particularly at low plasticizer content, finally leading to a decrease of the ductility. At higher plasticizer content, an increase of the ductility is observed, and PLA plasticized by 10% of CA showed a significant higher deformation at break than PLA plasticized by DEHP. In addition, plasticizer migration tests showed a lower weight loss of PLA plasticized by CA compared to DEHP plasticized PLA, which indicates the potential higher stability of properties of the cardanol derived plasticizer.