Biodegradation of poly(lactic acid)/regenerated cellulose nanocomposites prepared by the Pickering emulsion approach
2022
Cui, Lu | Yi, Lan | Hegyesi, Nóra | Wang, Yating | Sui, Xiaofeng | Pukánszky, Béla
Poly(lactic acid)/regenerated cellulose nanocomposites have been prepared by the Pickering emulsion approach. The composites contained 0, 0.5, 1.0, 1.5, 2.0 and 3.0 wt% nanocellulose. Plates compression molded from the composites were degraded enzymatically by Proteinase K with the daily change of the degradation medium. The results confirmed the excellent catalyzing effect of Proteinase K. The enzymatic degradation catalyzed by Proteinase K is very fast, considerable amount of lactic acid forms even in one day. The daily change of the medium allows the complete degradation of composite samples within one week. Degradation rate determined in this way is an average value; the rates are different each day. The effect of nanocellulose on the rate of degradation is quite complex. Overall degradation rate first increases from around 0.5%/h for the neat PLA to a maximum value of 0.8%/h at 0.5 wt% RC content and then decreases with increasing cellulose content back to around 0.5%/h as the amount of RC increases from 0.5 to 3 wt%, because of increased crystallinity and the formation of a network from the cellulose particles, which hinder the penetration of enzyme molecules into areas of the specimen degraded already. Composite structure changes considerably with increasing regenerated cellulose content, larger aggregates form leading to accelerated degradation.
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