Characterisation of solution cast cellulose nanofibre – reinforced poly(lactic acid)

Abstract

Cellulose nanofibres, 20 nm in diameter and 300 nm long, were prepared by acid hydrolysis of flax yarns. Com- posite films containing 2.5 and 5.0 wt% flax cellulose (FC) fibres were prepared by solution casting of mixtures of poly(lactic acid) (PLA) solution and cellulose nanofibre suspension in chloroform. The resulting composite films and solu- tion cast pure PLA film, with thickness of around 160 μm, showed good transparency. For composites with 2.5 and 5.0 wt% FC, the tensile strength increased by 25 and 59% and tensile modulus by 42 and 47%, respectively, compared to pure PLA film. The composite film with 2.5 wt% FC combined high strength and ductility with tensile strength of 24.3 MPa and 70% elongation at break. Flax cellulose appeared to facilitate nucleation and subsequent crystallisation of PLA more effectively in the amorphous composites than in the crystalline composites.