Project Description Wood fibres as prepared in defibrators commonly used for the manufacture of medium density fibreboard (MDF) have dimensions of around 30-100 micrometres diameter by 1-4 mm length. In addition to this, they are usually hollow tubes with the walls being of 2-20 micrometres thick. The walls are multi-layer composites of well-ordered but variously packed, so-called microfibrils in each layer1,2. Microfibrils are themselves composite structures of a central column of highly crystalline cellulose, embedded in a matrix of semi-crystalline hemicellulose and sheathed by a layer of amorphous lignin13. The fibres are held together by lignin4 and it is this lignin layer which is required to fail in the defibrillation step to yield the individual fibres. The defibrillation process however, does not generate uniform fibre quality and some fibres can break, some fibres may not fully separate and dust can also be generated. Furthermore the fibres are not usually linear shapes and can be twisted, bent or buckled. For completeness, it is also worth mentioning that there are usually 3 principle types of fibres (depending on the nature of the wood cell from which they are derived – the different cells have different lengths, wall thicknesses and lumen dimensions1. Additionally there are a number of other concerns which need to be considered in any examination of wood fibres such as (pit types, abundance and distribution, ray vs longitudinal fibres, radial vs tangential faces of the fibres, cross sectional shapes of the fibre, heartwood vs sapwood fibres, whether reaction wood is included in the mix or not and so on). The quality of the fibre, the resin and wax distribution over the fibre, the moisture and thermal history, the extent of compression of the fibres etc will all have a significant impact of the mechanical property set of the fibres which in turn (in combination with the adhesion process) will impact the performance set of the derived panel. Testing of final panel physical properties is relatively straight forward5,6,7,8,9: Multiple samples are easily cut from panels which can be tested using conventional tensile testing apparatus and so assessments of the bending strength, the shear and splitting strengths and moduli in different modes are measureable. However, such tests are, due to the nature of the wood, highly variable and so statistical assessment methods are utilized to give meaning to the results. Assessments of single fibres on the other hand are difficult. Manipulation of fibres of the aforementioned dimensions is very difficult and usually requires some modification to allow testing to happen. For example several research teams apply droplets of resin to the ends of the fibres which can then be used to affix clamps which in turn can then be pulled or bent to assess the performance of the fibres10. What this approach fails to acknowledge is that the ‘clamping’ resin may have a significant influence on the result. And since the fibres are so small in dimensions, the impact of the clamping resin could be quite significant. It is therefore desireable to develop a test method which can measure the mechanical performance of wood fibres (with/without resin), without the sample preparation method influencing the outcome. Dr. D. Jesson has demonstrated his idea of using modified atomic force microscopy to assess three point bending and thus to derive moduli and eventually bending strengths of single wood fibres (with and without resin)11. The initial screening study revealed comparatively large differences in behaviour between the fully resinated and non-resinated fibres which reassuringly demonstrates high sensitivity of the technique. Thus it can be anticipated that small, yet significant, changes to the quality of the fibre or the resin quality/distribution will be observable with the technique. The screening did also emphasise issues which would need to be resolved, which include but are not limited to the difficulties in handling the fibres, including aspects related to bent and twisted fibres, and the limited control of preparing controlled resin loadings and distributions on the fibres. Funding Notes Funded by EPSRC with eligibility criteria - see here View Website References Taken up at interview stage