A lot of food packaging is made from fossil-fuel based polymers. Bio-based polymers such as poly(lactic acid) (PLA) could be a more sustainable alternative to these materials. However, PLA is too brittle to be used for the fabrication of flexible food packaging films. Vegetable oils as biobased plasticizers could solve this problem.

Vimal Katiyar, Indian Institute of Technology Guwahati, India, and colleagues have investigated the use of coconut oil as a plasticizer for PLA. The team prepared blends of PLA with 1, 2, 5, and 7 wt% of coconut oil, respectively. The mixtures were dissolved in chloroform, poured into petri dishes, and dried to create polymer films.

The mechanical properties of the blends are improved compared with pure PLA. The tensile strength decreases at higher coconut oil contents and the material becomes more stretchable. The water vapor permeability of PLA is roughly halved after adding 7 wt% of coconut oil. The plasticized films were also more transparent than pure PLA. According to the researchers, coconut oil as nontoxic plasticizer could improve the flexibility of PLA films and give them suitable properties for food packaging applications.

• Plasticizing effect of coconut oil on morphological, mechanical, thermal, rheological, barrier, and optical properties of poly(lactic acid): A promising candidate for food packaging,
  Siddharth Mohan Bhasney, Rahul Patwa, Amit Kumar, Vimal Katiyar,
  J. Appl. Polym. Sci. 2017.
  DOI: 10.1002/app.45390