Effect of Nano-Clay and Surfactant on the Biodegradation of Poly(Lactic Acid) Films

This study examined the effect of nanoclays and surfactant on the hydrolytic degradation and biodegradation of poly(lactic acid) (PLA) and PLA nanocomposites. Organomodified montmorillonite (OMMT), unmodified montmorillonite (MMT) and an organomodifier (surfactant) for MMT (QAC) were extruded with PLA to produce PLA nanocomposites. The films were produced with the same initial molecular weight, thickness and crystallinity since these properties have a significant effect on the biodegradation process. The biodegradation experiments were carried out in an in-house built direct measurement respirometric system and were evaluated in inoculated vermiculite and vermiculite media for extended periods of time. Hydrolysis experiments were also conducted separately to decouple the abiotic/hydrolysis phase. The results showed no significant variation in the mineralization of PLA nanocomposites as compared to pristine PLA. The addition of nanoclays did not enhance the biodegradability of PLA when the initial parameters were strictly controlled. The hydrolysis test indicated that the nanoclays and surfactant did not aid in the degradation of PLA.

Poly(lactic acid)-Mass production, processing, industrial applications, and end of life

Global awareness of material sustainability has increased the demand for bio-based polymers like poly(lactic acid) (PLA), which are seen as a desirable alternative to fossil-based polymers because they have less environmental impact. PLA is an aliphatic polyester, primarily produced by industrial polycondensation of lactic acid and/or ring-opening polymerization of lactide. Melt processing is the main technique used for mass production of PLA products for the medical, textile, plasticulture, and packaging industries. To fulfill additional desirable product properties and extend product use, PLA has been blended with other resins or compounded with different fillers such as fibers, and micro- and nanoparticles. This paper presents a review of the current status of PLA mass production, processing techniques and current applications, and also covers the methods to tailor PLA properties, the main PLA degradation reactions, PLA products' end-of-life scenarios and the environmental footprint of this unique polymer.

Effects of Montmorillonite Content and Maleic Anhydride Compatibilization on the Mechanical Behavior of Polylactide Nanocomposites

The aim of this study was to investigate the effects of montmorillonite (MMT) type nanoclay content and maleic anhydride (MA) grafted polylactide (PLA) copolymer compatibilization on the mechanical properties of PLA nanocomposites; compounded by twin-screw extrusion melt-mixing followed with injection molding for shaping of bulk specimens. Successively intercalated and exfoliated structures of the nanocomposites were observed by XRD and TEM analysis, including the chemical interactions by FTIR. Mechanical tests indicated that use of only 1 wt% MMT resulted in significant improvements in many mechanical properties of PLA. Increases were only 14 % in flexural modulus and 7 % in flexural strength, but more than 6 times in ductility and as much as 85 % in fracture toughness values. After MA compatibilization these improvements were much enormous, being more than 22 times in ductility and 119 % in fracture toughness.