Development of Polylactic Acid-based Materials With Highly And Balanced Mechanical Performances Via Incorporating A Furan Ring-Containing Unsaturated Copolyester

Replacing petrochemical-based polymers with bio-based and biodegradable materials poses environmental, economic and safety challenges. Polylactic acid is considered to be one of the most promising alternatives due to its high mechanical strength and stiffness, biodegradability, biocompatibility and non-toxicity. However, its inherent brittleness and slow crystallization are the main drawbacks that severely limit the widespread commercialization and development. In the past few decades, extensive efforts have been made to strengthen PLA. In the current toughening strategy, physical blending with full / semi-bio-based flexible polymers or rubber has proven to be the most environmentally friendly, economical and effective solution.

In this paper, a novel bio-based unsaturated copolyester was synthesized by combining 1,5-pentanediol with flexible alkyl chain, dodecanoic acid with flexible alkyl chain, 2,5-furandicarboxylic acid with rigid ring structure and itaconic acid with carbon-carbon double bond. Through the simultaneous dynamic vulcanization and interfacial compatibilization of copolyester and polylactic acid induced by peroxide polyester, the obtained blends showed high and balanced mechanical properties, that is, the maximum elongation at break and notched impact strength were increased by 35 times ; the tensile strength is maintained at 57.4 MPa ( only decreased by 18 % ). It can be seen from the SEM images that the stretching of the copolyester domain induces the deformation of the contact PLA surface through strong interfacial bonds, which explains the toughening mechanism. This work provides a simple strategy for the manufacture of fully bio-based polymer materials with high comprehensive mechanical properties.