Engineered polylactide (PLA)–polyamide (PA) blends for durable applications: 1. PLA with high crystallization ability to tune up the properties of PLA/PA12 blends

Abstract

Polylactide (PLA), a biodegradable polyester produced from renewable resources, has a key position in the very promising market for bioplastics. Unfortunately, for utilization in durable/engineering applications, PLA suffers from some shortcomings such as low rate of crystallization, brittleness, and small ductility. The study proposes the use of PLA having high crystallization ability to tune up the properties of partly bio-based PLA/polyamide 12 (PA12) blends in presence of key additives. First, phenylphosphonic acid zinc salt (PPA-Zn) was selected as one of the most adapted nucleating agents (NAs) for PLA, whereas larger quantities of PLA(NA) have been produced for blending with PA12. The characterizations of PLA(NA) confirm dramatic improvements of PLA crystallization kinetics and an impressive degree of crystallinity (>40%). Blends having different PLA(NA)/PA12 ratios were prepared by melt-mixing with a laboratory micro-­compounder and characterized in terms of morphology, thermal stability, and with focus on the evidence of advanced crystallization properties. All differential scanning calorimetry measurements of PLA(NA)/PA12 blends suggest powerful nucleation and crystallization ability. Furthermore, addition of epoxy-functional styrene-acrylic compatibilizers into selected compositions by reactive extrusion (REX) was found to significantly change their morphology, preserving the properties of crystallization of PLA, with enhancements of mechanical properties (strength, ductility, impact resistance) confirmed by current prospects.