Photodegradation Investigation Points to Aloe Vera as a Photoprotector for Poly(Lactic Acid)

Renewable resources-based polymers have been the focus of materials science researchers since their use contributes to reducing carbon consumption and the environmental impacts in addition to decreasing the consumption of petroleum derivatives. Among renewable polymers, poly (lactic acid) (PLA) has emerged due to its biodegradable character and proper performance similar to the engineering resins. In this work, we investigated the effect of Aloe Vera (AV) as a photoprotective agent for PLA, since AV has polysaccharides and anthraquinones, such as acemannan and aloin, respectively, able to absorb and dissipate the innocuous energy generated by UV radiation. PLA/AV biocomposites were photodegraded in an aging chamber for 7, 14, 28, 56, and 112 days. Biocomposites with 10% AV displayed higher stability to photodegradation and a 96% reduction in the content of photodegraded material as evidenced by FTIR measurements, even in lower contents i.e., 1% AV decreased 50% of PLA photodegradation. It is suggested that hydrogen bonds between PLA ester group carbonyls and AV compounds’ hydroxyls contribute to the protective effect of AV. Photodegraded PLA/AV presented reasonable thermal stability, which is supposed to be influenced by PLA crosslinking. Acquired results point to AV as a proper candidate as a photoprotective agent for PLA, being environmentally friendly, as they are products from a renewable sources.