Changes of physical properties of PLA-based blends during early stage of biodegradation in compost
Language English Country Netherlands Media print-electronic
Document type Journal Article
PubMed
29454946
DOI
10.1016/j.ijbiomac.2018.02.078
PII: S0141-8130(17)33356-1
Knihovny.cz E-resources
- Keywords
- Biodegradation, Chemical changes, Composting, Crystallinity, Molecular weight,
- MeSH
- Time Factors MeSH
- Physical Phenomena MeSH
- Hydroxybutyrates chemistry MeSH
- Composting * MeSH
- Molecular Weight MeSH
- Plastics chemistry MeSH
- Polyesters chemistry metabolism MeSH
- Publication type
- Journal Article MeSH
- Names of Substances
- Hydroxybutyrates MeSH
- Plastics MeSH
- poly(lactide) MeSH Browser
- Polyesters MeSH
Three biodegradable plastics materials, namely pure poly(l-lactide) (PLA), PLA with plasticizer triacetine (TAC) and the mixture PLA/polyhydroxybutyrate (PHB) and TAC were investigated concerning changes of physical properties due to biodegradation in compost at 58°C up to 16days. With rising time of degradation in compost, both number and weight molecular masses were decreasing progressively, but only marginal change of the polydispersity index was observed which indicates that biodegradation is not random process. FTIR spectroscopy revealed that in spite of the extensive decrease of molecular weight, no substantial change in chemical composition was found. The most significant modification of the spectra consisted in an appearing of the broad band in region 3100-3300cm-1, which was assigned to a formation of biofilm on the sample surfaces. This effect appeared for all three materials, however, it was much more pronounced for samples containing also triacetine. Measurement of changes in crystalline portion confirmed that amorphous phase degrades substantially faster compared to crystalline part. The plasticizer triacetine is disappearing also rather fast from the sample resulting besides other effect also in a temporary increase of Tg, which at the beginning grows almost to the value typical for PLA without plasticizer but later the Tg is decreasing due to substantial changes in molecular weight. Generally during composting, the samples keep shape for up to 8days, after that time the material disintegrates to rough powder.
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