Laboratory-Scale Composting Test Methods to Determine Polymer Biodegradability: Model Studies on Cellulose Acetate

Richard A. Gross, Ji-dong Gu, David Eberiel, Stephen P. McCarthy

Research output: Contribution to journalArticlepeer-review

Abstract

Studies have been conducted to determine the time dependence of film normalized weight loss using in-laboratory simulations of a compost environment. The composting bioreactors contained a fresh synthetic waste mixture formulation which was maintained at 53°C and 60% moisture. An important result from these studies is that cellulose acetate (CA) films (approximate film thickness of between 0.025 and 0.051 mm) with degrees of substitution (DS) of 1.7 and 2.5 appeared completely disintegrated after 7 and 18 day exposure periods, respectively. Little weight loss of these films was noted under similar temperature and moisture conditions using abiotic controls. The testing protocol which was developed provided repeatable results on normalized film weight loss measurements. The dependence of the synthetic waste formulation used on polymer film weight loss was investigated using, primarily, CA DS-1.7 as a substrate. It was found that the time dependence of CA DS-1.7 film weight loss was virtually unchanged for five of the seven formulations investigated. However, two formulations studied resulted in relatively slower CA DS-1.7 film weight loss. Decreasing moisture contents of the compost from 60 to 50 and 40% resulted in dramatic changes in polymer degradation such that CA DS-1.7 polymer films showed an increase of the time period for a complete disappearance from 6 to 16 and 30 days, respectively. Also, a respirometric test method is described which utilizes predigested compost as a matrix material to support biological activity. Using this method, conversions to greater than 70% of the theoretical recovered CO2 for CA (1.7 and 2.5 DS) substrates were measured. Therefore, these results indicate high degrees of mineralization for CA with DS ≤ 2.5 under the appropriate disposal conditions.
Original languageEnglish
JournalJournal of Macromolecular Science, Part A
DOIs
StatePublished - 1 Apr 1995
Externally publishedYes

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