Polymer Submicron Fibre/Nanocellulose Hybrids and Composites

Abstract

Composite materials consist of at least two different materials, which when combined have engineering performance exceeding that of each individual component. Structurally, composites consist of a reinforcement embedded in a surrounding matrix. With increasing environmental awareness, the use of sustainable materials has gained significant importance. Nanofibrillated cellulose (NFC) can be obtained by mechanical disintegration of cellulose fibres (including pulp) and is a sustainable alternative reinforcing agent due to its excellent mechanical and barrier properties in film/paper form.

Electrospun poly(vinyl alcohol) (PVA) and solution blow spun poly (L-lactic acid) (PLLA) fibres with diameters in the sub-micrometre range were combined with NFC to obtain polymer fibre/NFC hybrid films. Polymer fibre/NFC hybrid films over the full composition range from 0 – 100 % NFC were produced. The tensile properties of the hybrid films increased with increasing NFC content, even under wet conditions. The combination of poly(vinyl alcohol) and nanocellulose resulted in hybrid films with a low oxygen transmission rate of 1.00 ± 0.37 cm³/(m² 24h 0.1 MPa) and lower water vapour transmission rates as compared to NFC films.

PVA/NFC and PLLA/NFC preforms were consolidated into NFC reinforced PVA and PLLA composites with a reinforcement content ranging from 0% to 100% whose tensile properties increased under dry and wet conditions with increasing NFC loading. Low oxygen transmission rates of around 1 cm³/(m² 24h 0.1 MPa) were determined for PVA/NFC composites. The polymer matrices reduced the water ab/sorption and water vapour permeability.

Date of Award	26 Sept 2023
Original language	English
Awarding Institution	City University of Hong Kong
Supervisor	Kwok Yiu Robert LI (Supervisor) & Bismarck ALEXANDER (External Co-Supervisor)