Acetylation of plant fibres

Disgrifiad o Effaith

The impact of our work has been to show that non-toxic wood preservation systems can be highly effective in preventing decay, dimensional instability and breakdown due to surface weathering of modified wood. This has led many other research groups to enter the field and to commercialisation of this (e.g. Accoya) and a variety of other modification processes for wood and for plant based fibres. The impact of this is important because plant-based materials of this type have a much lower environmental impact than other structural materials.

The impact of our work has been to show that non-toxic wood preservation systems can be highly effective in preventing decay, dimensional instability and breakdown due to surface weathering of modified wood. This has led many other research groups to enter the field and to commercialisation of this (e.g. Accoya) and a variety of other modification processes for wood and for plant based fibres. The impact of this is important because plant-based materials of this type have a much lower environmental impact than other structural materials.

Disgrifiad o'r ymchwil sylfaenol

In a pioneering study, Hill found that cell wall micro-compressive defects in plant fibres greatly reduce the toughness of composites leading to premature failure. Hill and Hale demonstrated the potential of chemical modification of a range of plant fibre types to improve their decay resistance for use in composites.
Hill led the network Chemical Modification and Metal Carboxylates in the COST E2 action on Wood Durability.

•In 1993 wood was being preserved for high performance using chromated-copper-arsenate (CCA) preservatives and creosote and few treatments which were compatible with plant fibre bonding were available. Although effective these treatments had little impact on dimensional stability and left toxic residues in the wood, an end-of-life cycle issue. Although a sustainable material wood was losing market acceptability due to decay and was being replaced by less sustainable materials, including plastics, cement and metals. By 2003 CCA and creosote use was severely restricted in developed countries and substitute preservatives of unproven long term efficacy were introduced, based on copper and co-biocides. In practice these have not proved as robust as CCA when applied industrially. Since then a number of highly effective chemical modification treatments have been successfully commercialised. Research by the Bangor team was significant in the introduction of these alternative treatments.
In lab tests under a variety of severe exposure systems which were later corroborated by long term field trials it was shown that acetylated plantation grown softwoods and hardwoods can be substantially protected against moisture sorption/desorption instability and fungal decay. The underlying mechanisms for this protection were evaluated with a variety of cell wall modifiying systems and linked with the effects on the cell wall porosity (solute exclusion, nitrogen sorption) and behaviour (sorption/ desorption, shrinkage/swelling). This relates to the accessibility of wood cell walls to low molecular weight degradative agents. This work has been subsequently broadened to apply acetylation and other forms of modification, either chemical or thermal, to wood or other plant fibre sources, where novel, renewable products, may be fabricated.
An outline of what the underpinning research produced by the submitted unit was (this may relate to one or more research outputs, projects or programmes).
The group showed that acetylated wood was resistant to decay under extreme conditions of exposure, showed that this was due to reactions occurring deep within the wood cell wall and provided evidence that this was as a result of blocking of the key degradative agents produced by decay organisms.
•Dates of when it was carried out.
Work on chemical modification by this group has been on-going in 1993-2007
•Names of the key researchers and what positions they held at the institution at the time of the research (where researchers joined or left the HEI during this time, these dates must also be stated).
•Professor W.B. Banks 1993-1997
•Professor C.A.S. Hill 1994-2007
•Dr. M.D. Hale 1993 to date
•Dr. G. Ormondroyd PhD student and then subsequently BC staff member.
•[Perhaps Dr. Morwenna. J. Spear, Mastery Fahani, Antonios Papadopolous, Dennis Jones, Simon Forster]
•Any relevant key contextual information about this area of research. In 1993 wood was being preserved for high performance using chromated-copper-arsenate (CCA) preservatives and creosote and few treatments which were compatible with plant fibre bonding were available. Although effective these treatments had little impact on dimensional stability and left toxic residues in the wood, an end-of-life cycle issue. Although a sustainable material wood was losing market acceptability due to decay and was being replaced by less sustainable materials, including plastics, cement and metals. By 2003 CCA and creosote use was severely restricted in developed countries and substitute preservatives of unproven long term efficacy were introduced, based on copper and co-biocides. In practice these have not proved as robust as CCA when applied industrially. Since then a number of highly effective chemical modification treatments have been successfully commercialised. Research by the Bangor team was significant in the introduction of these alternative treatments.

Statws effaith	Potensial