Tailoring and Long-Term Preservation of the Properties of PLA Composites with "Green" Plasticizers

• Published in: Polymers Vol. 14; no. 22; p. 4836
• Main Authors: Murariu, Marius, Paint, Yoann, Murariu, Oltea, Laoutid, Fouad, Dubois, Philippe
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 10.11.2022; MDPI
• Subjects: Aging; anhydrite II (AII); Biodegradation; calcium sulfate; Composite materials; composites; Crystallization; Ductility; Ductility tests; Epoxy resins; Extrusion; Flexibility; Glass transition temperature; Impact resistance; Mechanical properties; Molecular weight; Oligomers; Phthalates; plasticizer; Plasticizers; poly(lactic acid) PLA; Polylactic acid; Polymers; Rheological properties; Rheology; Stiffness; Textile fibers; Thermodynamic properties; Thermoforming; tributyl citrate (TBC); Tubes; Viscosity; United Kingdom; composites; melt rheology; tributyl citrate (TBC); anhydrite II (AII); thermal and mechanical properties; chain extender (CE); poly(lactic acid) PLA; reactive extrusion (REX); calcium sulfate; toughness; film aging; plasticizer
• ISSN: 2073-4360; 2073-4360
• DOI: 10.3390/polym14224836

Concerning new polylactide (PLA) applications, the study investigates the toughening of PLA-CaSO β-anhydrite II (AII) composites with bio-sourced tributyl citrate (TBC). The effects of 5-20 wt.% TBC were evaluated in terms of morphology, mechanical and thermal properties, focusing on the enhancement of PLA crystallization and modification of glass transition temperature (T ). Due to the strong plasticizing effects of TBC (even at 10%), the plasticized composites are characterized by significant decrease of T and rigidity, increase of ductility and impact resistance. Correlated with the amounts of plasticizer, a dramatic drop in melt viscosity is also revealed. Therefore, for applications requiring increased viscosity and enhanced melt strength (extrusion, thermoforming), the reactive modification, with up to 1% epoxy functional styrene-acrylic oligomers, was explored to enhance their rheology. Moreover, larger quantities of products were obtained by reactive extrusion (REX) and characterized to evidence their lower stiffness, enhanced ductility, and toughness. In current prospects, selected samples were tested for the extrusion of tubes (straws) and films. The migration of plasticizer was not noted (at 10% TBC), whereas the mechanical and thermal characterizations of films after two years of aging evidenced a surprising preservation of properties.