DOI: 10.1002/app.54501 ISSN: 0021-8995

Improvement of melt viscosity and compatibility of polyglycolic acid (PGA)/polylactic acid (PLA) blend via reactive blending with bifunctional and multifunctional hybrid chain extender

Deguo Liu, Qimeng Xie, Ziwei Liu, Ju Chen, Xiaoxuan Zou, Bo Jing
  • Materials Chemistry
  • Polymers and Plastics
  • Surfaces, Coatings and Films
  • General Chemistry


The low melt viscosity and melt strength of polyglycolic acid (PGA) severely limit its application. In this work, high melt viscosity PGA/PLA blends are prepared by reactive extrusion of bifunctional isocyanate (HDI) and multifunctional epoxy oligomer (ADR) as chain extenders. The use of hybrid chain extender (hCE) containing 2 wt% HDI and 1 wt% ADR results in a long chain branched/cross‐linked structure, thus increasing melt viscosity more effectively than HDI or ADR alone. The complex viscosity, storage modulus and loss modulus of the PGA/PLA/hCE blends are significantly higher than those of the PGA/hCE. The 60PGA/40PLA/hCE has the highest complex viscosity of 72,115 Pa s, which is 69 times of that of PGA/hCE. The modification of hCE significantly improved the mechanical performance of PGA/PLA blend, with the 60PGA/40PLA/hCE having the highest tensile strength and flexural strength. The crystallization temperature and crystallinity of the PGA component in the PGA/PLA/hCE blend are significantly reduced in comparison to that of the PGA/hCE. The PGA/PLA/hCE has the best thermal stability, with the T−5% of 355.3°C, almost 45°C higher than pure PGA. The SEM results show that the adding of hCE decreased the domain size of the PLA dispersed phase in PGA/PLA blend, due to the in situ compatibilization.

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