Thiophosphate esters of cashew nutshell liquid derivatives as new antioxidants for poly(methyl methacrylate)

In this work, poly(methyl methacrylate) films 1% additivated with new thiophosphate esters antioxidants derived from technical Cashew Nutshell Liquid (CNSL), a byproduct of the cashew nut (Anacardium occidentale L.) industry, were investigated by thermogravimetry (TG/DTG) and differential scanning calorimetry (DSC) measurements under inert (N₂) and oxidative (synthetic air) atmospheres. Three new products were synthesized and characterized by GC/MS, ¹H and ³¹P NMR. The analyses were focused on the onset (T _e) and offset temperature (T _o) of degradation of the films, and on the maximum degradation temperature (T _MAX). It was observed that the thermal stability of the films increased with the addition of the thiophosphate ester antioxidants, which indicates that CNSL could be used as a natural source of phenolic material for the synthesis of antioxidants.