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 T g of PLA films decreases with addition of the oligomer. A decrease of about 10 °C in the T g 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 ( X c ) 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.