PLA properties can be altered or improved by use of additives and developing polymer blends. Some of the examples are:
Plasticization: Lactide monomer is an excellent plasticizer for PLA however it tends to migrate to the PLA surface. Other plasticizers such as Citrate esters & low-Mw PEG have shown only modest improvements in toughness, but this is accompanied by a dramatic loss in tensile stress at break and tensile modulus.
Mineral Fillers such as ppt CaCO3 at 30% loading provides substantial improvement in the impact toughness of PLA.
Impact modifiers are also found to increase PLA properties however adding them will compromised the compostability of the PLA.
Polymer Blending: PLA/PCL blends Polycaprolactone (PCL) is also a degradable polyester and due to its low Tg it exhibits rubbery characteristics with an elongation at break of approximately 600%, which makes it an ideal candidate for toughening polylactide.
PLA blends with PHA have shown significant improvement in impact toughness with a modest decrease in modulus and strength as well as without compromising bio-based content and compostability of PLA.
The development of PLA nanocomposites using nanoscale fillets represents a better alternative to traditional composites. Due to their high surface area, improved matrix adhesion and aspect ratio these nanofillers (colloidal silica, clay platelet...) offer enormous advantages over traditional macro- or micro-particles (e.g., talc, glass, and carbon fibers). For example, PLA-clay nanocomposites show improved mechanical, barrier optical, and thermal properties.
