Modification of poly(lactic acid) using itaconic anhydride by reactive extrusion

• Itaconic anhydride was grafted onto PLA using reactive extrusion.
• The highest degree of grafting was 0.75% at 1 wt.% DCP and 6% IA.
• Using a high DCP concentration decreased the material’s melting temperature.
• Grafted PLA had a higher thermal stability due to increase crystallinity.
• Tensile strength and elongation at break increased after grafting.

Itaconic anhydride (IA) was grafted onto poly(lactic acid) (PLA) using dicumyl peroxide (DCP) as radical initiator using free-radical grafting. Different concentrations of monomer (2–6 wt.%) and initiator (0.5–0.75 wt.%) at 180 and 200 °C were used for chemical modification. Grafting was confirmed using titration and the highest degree of grafting was 0.75%. The degree of grafting increased gradually with increasing IA and DCP concentration, with minimal chain scission. Reaction kinetics showed that the initial rate of reaction was between 0.024 and 0.03 (l/mol s)1/2, depending on temperature. Grafted PLA showed a significant change in enthalpy of crystallization, enthalpy of fusion as well as increased tensile strength and elongation at break accompanied by a reduction in stiffness.

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