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. 2018 Oct 18;23(10):2682.
doi: 10.3390/molecules23102682.

Melt Viscoelastic Assessment of Poly(Lactic Acid) Composting: Influence of UV Ageing

Vincent Verney  1 , Audrey Ramoné  2 , Florence Delor-Jestin  3 , Sophie Commereuc  4 , Marek Koutny  5 , Geoffrey Perchet  6 , Julien Troquet  7
Affiliations

Melt Viscoelastic Assessment of Poly(Lactic Acid) Composting: Influence of UV Ageing

Vincent Verney et al. Molecules. .

Abstract

This study is devoted to the degradation pathway (bio, photo degradation and photo/bio) of Poly(Lactic acid) PLA polymers by means of melt viscoelasticity. A comparison was made between three PLA polymers with different microstructures (L, D stereoisomers). Biodegradability was determined during composting by burying the polymer films in compost at 58 °C. Melt viscoelasticity was used to assess the molecular evolution of the materials during the composting process. Viscoelastic data were plotted in the complex plane. We used this methodology to check the kinetics of the molecular weight decrease during the initial stages of the degradation, through the evolution of Newtonian viscosity. After a few days in compost, the Newtonian viscosity decreased sharply, meaning that macromolecular chain scissions began at the beginning of the experiments. However, a double molar mass distribution was also observed on Cole⁻Cole plots, indicating that there is also a chain recombination mechanism competing with the chain scission mechanism. PLA hydrolysis was observed by infra-red spectroscopy, where acid characteristic peaks appeared and became more intense during experiments, confirming hydrolytic activity during the first step of biodegradation. During UV ageing, polymer materials undergo a deep molecular evolution. After photo-degradation, lower viscosities were measured during biodegradation, but no significant differences in composting were found.

Keywords: PLA; biodegradation; photo-degradation; rheology.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Scheme 1
Scheme 1
Complex plane representation: Cole–Cole plots.
Figure 1
Figure 1
Cole–Cole plot of aged and non-aged PLA4042D.
Figure 2
Figure 2
Cole–Cole plots of PLLA, PDLA and PLA4042D during composting (0 to 46 days). Viscoelastic experiments were performed at T = 180 °C.
Figure 3
Figure 3
Zero shear viscosity evolution during composting of PLLA, PDLA and PLA4042D.
Figure 3
Figure 3
Zero shear viscosity evolution during composting of PLLA, PDLA and PLA4042D.
Figure 4
Figure 4
Cole–Cole plots of PLLA, PDLA and PLA4042D non-aged and photo-aged during composting (0 until to 7 days). Unfilled symbols: after 100 h of photo-ageing; filled symbols non-aged. Viscoelastic experiments have been performed at T = 180 °C.
Figure 4
Figure 4
Cole–Cole plots of PLLA, PDLA and PLA4042D non-aged and photo-aged during composting (0 until to 7 days). Unfilled symbols: after 100 h of photo-ageing; filled symbols non-aged. Viscoelastic experiments have been performed at T = 180 °C.
Figure 5
Figure 5
Variation of the Newtonian viscosity versus time of composting for PLA 4042D, 100 h UV aged and non-aged.
Scheme 2
Scheme 2
Mechanism of PLA hydrolysis.
Figure 6
Figure 6
FTIR spectra of PLLA films during composting (0 until to 28 days) in the region of 4000−400 cm−1.
Figure 7
Figure 7
FTIR spectra of PLA films before and after 25 days of biodegradation in the region of 1000−600 cm−1.
Figure 8
Figure 8
A921/A956 evolution during composting (0 until to 45 days).
See this image and copyright information in PMC

References

    1. Mooney B.P. The second green revolution? Production of plant-based biodegradable plastics. Biochem. J. 2009;418:219–232. doi: 10.1042/BJ20081769. - DOI - PubMed
    1. Huang J.-C., Shetty A.S., Wang M.-S. Biodegradable plastics: A review. Adv. Polym. Technol. 1990;10:23–30. doi: 10.1002/adv.1990.060100103. - DOI
    1. Song J.H., Murphy R.J., Narayan R., Davies G.B.H. Biodegradable and compostable alternatives to conventional plastics. Philos. Trans. R. Soc. B Biol. Sci. 2009;364:2127–2139. doi: 10.1098/rstb.2008.0289. - DOI - PMC - PubMed
    1. Hakkarainen M. Degradable Aliphatic Polyesters. Springer; Berlin/Heidelberg, Germany: 2002. Aliphatic polyesters: Abiotic and biotic degradation and degradation products; pp. 113–138.
    1. Quynh T.M., Mitomo H., Nagasawa N., Wada Y., Yoshii F., Tamada M. Properties of crosslinked polylactides (plla & pdla) by radiation and its biodegradability. Eur. Polym. J. 2007;43:1779–1785.

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