Effect of simulated mechanical recycling processes on the structure and properties of poly(lactic acid)

Abstract

The aim of this work is to study the effects of different simulated mechanical recycling processes on the structure and properties of PLA. A commercial grade of PLA was melt compounded and compression molded, then subjected to two different recycling processes. The first recycling process consisted of an accelerated ageing and a second melt processing step, while the other recycling process included an accelerated ageing, a demanding washing process and a second melt processing step. The intrinsic viscosity measurements indicate that both recycling processes produce a degradation in PLA, which is more pronounced in the sample subjected to the washing process. DSC results suggest an increase in the mobility of the polymer chains in the recycled materials; however the degree of crystallinity of PLA seems unchanged. The optical, mechanical and gas barrier properties of PLA do not seem to be largely affected by the degradation suffered during the different recycling processes. These results suggest that, despite the degradation of PLA, the impact of the different simulated mechanical recycling processes on the final properties is limited. Thus, the potential use of recycled PLA in packaging applications is not jeopardized.

3D printing filament as a second life of waste plastics—a review

“…In opposite, significant decrease in the viscosity observed in the case of washed PLA wastes, results from influence of high temperature and shear stress during the polymer reprocessing. The degradation during the accelerated ageing can also contribute to this process (Beltrán et al 2018) An addition of oxidative stabilizers (quinone) and residual catalyst stabilizers (tropolone) to a neat polymer significantly limits the rheological degradation. The data obtained clearly identified that recycling reduces the mechanical strength of PLA.…”

“…Determining the impact of recycling on the properties of polymers used for 3D printing is an important issue. It turns out that recycling with a washing stage results in a 20% decrease in PLA molecular weight (Beltrán et al 2018).…”

Multiscale analysis on multiextruded poly(lactic acid)/organoclay nanocomposites: Insights into the underlying mechanisms of thermomechanical degradation

“…The reduction in molecular mass and introduction of new groups during degradation could further change the crystalline structure and might give rise to deteriorated mechanical properties of PLA. However, discrepant results have been reported 10‐12 . For instance, Pillin et al 12 reported that PLA displays declined fracture strength and strain‐at‐break after seven injection molding cycles.…”

Studies on Blending Properties of Poly Lactic Acid and Starch with Methylene Diphenyl Diisocyanate

“…However, PCL and EVOH are fossil fuel-derived plastics that increase carbon dioxide in the environment and stimulate the greenhouse effect. A thermo plastic polymer from a renewable source would be better for the development of a biodegradable plastic [5][6][7][8]. Poly Lactic Acid (PLA) is polyester made from L-or D -lactic acid.…”