School of Engineering and Materials Science Research
All-cellulose composites by selective fibre surface dissolution process; Processing schematic (top) and pictures of all-cellulose composites based on cellulose paper (bottom). Increasing dissolution time leads to high-strength transparent films (photo courtesy: Prof. T Nishino, Kobe Univ., Japan)
Binder-free fully biobased all-cellulose composites based on nano-sized cellulose fibres through increased intra-fibre H-bonding
In recent years, a significant amount of research has been devoted to the use of ligno-cellulose fibres such as flax, hemp, ramie or sisal fibres as replacement for glass fibres in polymer composites. Alternative routes to environmentally friendly polymer composites have focussed on so-called single polymer composites or self-reinforced polymer composites, which follow mono-material based eco-design concepts. A combination of trends towards natural fibre reinforcement and single polymer composites has recently led to some initial works on the development of all-cellulose composites. Various studies have reported the manufacture of all-cellulose composites using partial dissolution of cellulose fibres. During composite preparation, rather than selectively melting fibre surfaces as in the case of thermoplastic sr-PP composites, here the surface layer of cellulose fibres is partially dissolved to form the matrix phase of the all-cellulose composites. Meanwhile, the remaining cellulose fibre cores maintain their original molecular orientation, providing strength and stiffness to the composite.
More recently the group has also been exploring the use of H-bonded cellulose nanofibre networks as a method to make fully biobased all-cellulose composites. In order to obtain fully recyclable and biodegradable materials, all-cellulose fibrous sheets and panels based on nano-sized bacterial cellulose or plant or wood fibres have been developed without the additional use of bonding agents or resins as in the case of e.g. phenolic resin based MDF or natural fibre reinforced plastics. The group has been involved in a recent collaborative R&D programme with the objective of producing a sustainable, recyclable hard flooring system from cellulose-based Zelfo®. Research and development work has been carried out in the UK with Technology Strategy Board funding, under the Design & Manufacture of Sustainable Products Call. In addition to Omodo GmbH, the original Zelfo® patent holders, other partners included InterfaceFLOR; Brunel Univerity; BioRegional Development Group; Heineken UK; Hemp Technology, and the UK’s National Non-Food Crop Centre (NNFCC).