Poly(lactic acid)/polyoxymethylene blends: Morphology, crystallization, rheology, and thermal mechanical properties

• PLA/POM blends were prepared through melt compounding.
• The HDT of the blend with 50% POM (133 °C) was about twice that of the neat PLA (65 °C).
• The tensile modulus exhibited a synergistic effect, as the blend had a greater modulus than neat PLA or POM.
• The stacked phase structure of the blends resulted in enhanced HDT and superior mechanical performance.

Poly(lactic acid)/polyoxymethylene (PLA/POM) blends were prepared through melt compounding in an attempt to improve the heat resistance of PLA. The effects of POM on the immiscibility, dynamic and quasi-static mechanical properties, rheological properties, and heat resistance were examined in detail with various techniques. PLA was found to be immiscible with POM, evidenced by both phase-separated morphology and two glass transition temperatures of the blends. The heat deflection temperature of PLA was nearly doubled, increasing from 65 to 133 °C, when the POM content approaches 50%. The tensile modulus exhibited a synergistic effect, as the blend has a greater modulus than neat PLA or POM. Because the PLA in the injection molded test samples was totally amorphous as revealed by the WXRD result, the enhanced HDT and superior mechanical properties were mainly attributed to the unique stacked layer structure of the blends.

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