Mechanical and thermal properties of poly(lactic acid) plasticized with dibutyl maleate and fumarate isomers: Promising alternatives as biodegradable plasticizers

•Dibutyl maleate and fumarate induces the plasticization of poly(lactic acid)•Plasticizers cis–trans isomerism affects thermal and mechanical properties.•Dibutyl fumarate (trans) more efficiently plasticizes PLA than dibutyl maleate (cis)•To observe the plasticizing effect, a content threshold must be reached.