Development and Characterisation of Poly(butylene adipate-co-terephthalate)- Silane Modified Cellulose Nanocrystals Composite Materials and Films

In the pursuit of a sustainable and pollution free environment, the need for bioplastic alternatives that satisfy many of the performance demands of persistent petroleum-derived plastics is paramount. Biopolymer films reinforced with nanostructures have become an interesting area of research. Poly(butylene adipate-co-terephthalate) (PBAT) is a synthetic polymer capable of biodegrading at ambient temperature. The polar nature of cellulose nanocrystals (CNCs) used as additive in PBAT matrix makes its dispersion challenging. In this work silylation was achieved by partial substitution of surface hydroxyl groups of nanocellulose with hydrophobic silicone moieties. The surface of nanocellulose was initially modified by 5 wt.% of triethoxyvinylsilane (TEVS) or trimethoxyphenylsilane (TMPS) and melt blended into the PBAT matrix. Phenyl modified nanocellulose used as additive in PBAT matrix achieved uniform dispersion. The phenyl silane modified CNCs based composite film had 12% higher tensile strength and -58% higher modulus of elasticity than pristine PBAT films. The phenyl silane modified CNCs substantially reduced the permeability of the composite films against both water vapour and oxygen. Food packaging applications may benefit from this material as it could meet many of the performance requirements in terms of morphological, mechanical, thermal and barrier properties.