Preparation and characterisation of polylactic acid composites/nanocellulose extracted from Eucomis autumnalis for various applications

Abstract

Polymers produced in living cells have attracted exceptional attention due to their ecofriendliness and biodegradability. These polymers possess similar properties to conventional plastics, making them suitable potential plastic substitutes for sustainable development and conservation of finite oil resources. Polylactic acid (PLA) is comparable to commonly used plastics but is inferior due to poor impact resistance, hydrophobicity, a lack of reactive side chain groups, a slow degradation rate, and a relatively high cost. However, PLA can benefit from the incorporation of various polymer components with complementary properties to yield improved physical properties. Developing fully bio-based composites of PLA and cellulose is particularly interesting. They have mechanical and physiological properties that make them more suitable for a wider range of applications. Herbaceous plant cell walls comprise semicrystalline cellulose fibres embedded in a soft matrix. The crystalline part of the inherently stiff chains extracted from plants such as E. autumnalis is subject to research for potential roles as fillers. In this study, to fabricate a novel composite consisting of PLA/Cellulose (stem) (PLA/Cs), three characteristically different celluloses were extracted from various parts of E. autumnalis (bulbs, leaves, and stem). Based on a distinguished cellulose spectrum (showing all the relevant functional groups), increased crystallinity and thermal stability compared cellulose from the leaves, varying contents (99.5/0.5 and 97/3.0 PLA/Cs) of a mixture of fibre bundles and coarse aggregates of cellulose from the stems were incorporated in a PLA matrix. The surface morphology and structural properties of the novel composites were investigated using FTIR and SEM. In addition, the thermal and mechanical properties of the composites were investigated using standard techniques (i.e., TGA and Tensile). Generally, there was better distribution of Cs in PLA and improved interfacial adhesion at high filler content (97/3.0), resulting in a high Young's modulus. However, no significant improvement in thermal properties was observed.