Oligomalonate Plasticized Poly(Lactic Acid) Films: Crystallization, Thermal, and Mechanical Properties

The biodegradable aliphatic oligoester oligo(trimethylene malonate) (OTM) is synthesized by polycondensation and used to plasticize poly(lactic acid) (PLA). Casting films of PLA and PLA/OTM with concentrations of 1, 5,and 10 wt.% are prepared, and these films are characterized by thermal analyses, rheology, and mechanical tests. DSC revealed that the Tg of PLA films decreases with addition of the oligomer. A decrease of about 10 °C in the Tg is attained when 10 wt% of the oligomer is added to the polymer. Addition of OTM to PLA slightly decreases the thermal stability and does not change significantly the degree of crystallinity (Xc) of the films. Dynamic‐mechanical analyses of these casting films show that the PLA/OTM systems presented lower storage modulus than PLA and mechanical test shows an increased in the elongation at break for PLA films containing the oligoester up to 200%. The results make possible to conclude that the oligomer synthesized from bio‐based monomers acts as a plasticizer of PLA increasing the PLA flexibility.