Thermal properties and non-isothermal crystallization kinetics of biocomposites based on poly(lactic acid), rice husks a

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Thermal properties and non‑isothermal crystallization kinetics of biocomposites based on poly(lactic acid), rice husks and cellulose fibres Luboš Běhálek1   · Martin Borůvka1 · Pavel Brdlík1 · Jiří Habr1 · Petr Lenfeld1 · Dora Kroisová2 · Filip Veselka1 · Jan Novák1 Received: 2 August 2019 / Accepted: 1 June 2020 © Akadémiai Kiadó, Budapest, Hungary 2020

Abstract Bioplastics reinforced by agricultural waste fibres show promise to provide degradation back into the environment when they are no longer needed. These biocomposites have the potential to replace synthetic polymers from non-renewable resources in some applications and may turn out to be one of the material revolutions of this century. Unlike synthetic composites, biocomposites are renewable, carbon neutral, biodegradable and non-petroleum based and have low environmental, human health and safety risks. In this paper, poly(lactic acid) (PLA)-based biocomposites filled with technical cellulose fibres (CeF) and rice husks (RHs) at 10–30 mass% loading were prepared by twin-screw extrusion and injection moulding to enhance stiffness of resulting biocomposites. Particular attention was given to the enhancement of adhesion between the polymer matrix and natural filler through the physical modification by ozone ­(O3) and dielectric barrier discharge (DBD) plasma (p) surface treatments. Further than, compatibilizing agent based on PLA-g-MAH was produced and introduced into the PLA systems. The non-isothermal crystallization behaviour and thermal properties were investigated through differential scanning calorimetry (DSC) under various cooling rates (5, 10, 20 and 40 °C m ­ in−1). The addition of both fillers increased overall crystallization kinetics of resulted biocomposites, especially at high cooling rates. An increase in crystallinity degree from 2.4 (neat PLA) up to 51% has been observed for PLA/30CeFO3 samples at 40 °C ­min−1 cooling rate. An increase in crystallinity degree based on mass percentage of filler was noticed especially for PLA/RH. Mass percentage increase in CeF did not notice significant increase in PLA crystallinity. The influence of RH and CeF on transformation behaviours of PLA αʹ-/αpolymorphs was observed. The elimination of imperfect αʹ-crystals was observed with increasing amount of RH and CeF. Keywords  Biocomposites · Poly(lactic acid) · Cellulose · Rice husks · Surface treatment

Introduction Plastics are petroleum-based products that became a requisite part of our daily life in the last century. Consequently, questions about petroleum sources capacity and environmental pollution are nowadays more and more important. Therefore, many researchers and companies are focused on developed * Luboš Běhálek [email protected] 1



Department of Engineering Technology, Faculty of Mechanical Engineering, Technical University of Liberec, Liberec, Czech Republic



Department of Material Science, Faculty of Mechanical Engineering, Technical University of Liberec, Liberec, Czech Republic

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biodegradable materials made from renewable sources [1