Effect of different mechanical recycling processes on the hydrolytic degradation of poly(l-lactic acid)
| Autor: | M.U. de la Orden, Vicente Lorenzo, Freddys R. Beltrán, Joaquín Martínez-Urreaga |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
chemistry.chemical_classification
Materials science Absorption of water Polymers and Plastics Compression molding 02 engineering and technology Polymer 010402 general chemistry 021001 nanoscience & nanotechnology Condensed Matter Physics 01 natural sciences Accelerated aging 0104 chemical sciences law.invention Hydrolysis chemistry Mechanics of Materials law Materials Chemistry Degradation (geology) Gravimetric analysis Composite material Crystallization 0210 nano-technology |
| Zdroj: | Polymer Degradation and Stability. 133:339-348 |
| ISSN: | 0141-3910 |
| DOI: | 10.1016/j.polymdegradstab.2016.09.018 |
| Popis: | The growing production of poly(lactic acid) (PLA) has increased the interest for the mechanical recycling of this polymer. The main objective of this work is to study the effect of different mechanical recycling processes on the hydrolytic degradation of PLA. A commercial grade of PLA was subjected to two different recycling processes, one of them comprising an accelerated thermal and photochemical aging and a second melt compounding and compression molding step, and other including a demanding washing step after the accelerated aging process. The accelerated aging and, especially, the washing step had a significant effect on degradation during recycling. Samples of virgin and recycled plastic immersed in a phosphate buffered solution at 37 or 58 °C were removed at selected times and then characterized by gravimetric analysis, IR and UV spectroscopy, thermal analysis, x-ray diffraction and microhardness and viscosity measurements. The water absorption process, at both temperatures, can be modeled using a Fickian model only when the immersion times were short. The different recycling processes caused an increase of the diffusion coefficient of PLA at 37 °C, while at 58 °C the differences were smaller. DSC results pointed out that mechanical recycling promotes a slight crystallization of PLA at 37 °C that explains the increasing of the hardness during the hydrolysis. |
| Databáze: | OpenAIRE |
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