The dimensional stabilisation imparted to Corsican pine sapwood by chemical modification with carboxylic acid anhydrides of varying chain length was investigated. Dimensional stabilisation was determined by the water soak/oven dry method through a total of ten cycles in order to determine the stability of the ester bond to hydrolysis at neutral pH. These tests indicated that the dimensional stabilisation was attributable solely to a bulking effect. The loss of material due to hydrolysis was minimal, with modified wood blocks exhibiting lower weight loss following water soaking than unmodified blocks. Considerable variation in dimensional stabilisation (as determined by volumetric swelling coefficient and anti-shrink efficiency) was found throughout the water soak tests. A contribution to this variability was found to be due to changes in the water saturated volume caused by variations in the ambient air temperature, h was found that weight percent gain provided an excellent measure of dimensional stabilisation irrespective of the chain length of the anhydride involved. Increases in volume due to modification were found to be larger than theoretically expected. IntroductionVarious chemical modifications have been investigated for improving the dimensional stability, and decay resistance of wood (Rowell 1983;Kumar 1994). Of all the methods investigated, modification using acetic anhydride has received by far the most attention, and will in all likelihood form the basis for a commercial process in the near future (Sheen 1992). However, in spite of intensive investigations into acetylation, there is little evidence in the literature of the effect of higher homologues upon the dimensional stabilisation of wood. Despite an exhaustive search of the literature, we are aware of only two publications dealing with higher homologues (Rugevista and Embreksha 1988;Goldstein et al. 1961). There has been no comprehensive study of the effect of chain length of a single modifying agent upon the dimensional stabilisation of wood although Goldstein et al. did study the effect of chain length upon reaction rate. The effect of carbon chain length of a series of linear chain anhydrides upon dimensional stabilisation of wood samples has been investigated and the results are presented in this paper. Since variation in chain length would affect hydrophobicity of the substrate, it is possible to determine whether dimensional stabilisation arises purely from a bulking effect or is in part due to denial of access

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Scots pine sapwood reinforced with Na2SiO3 and nano-TiO2 shows a potential for the exploration of a broader range of wood hardness and flame-retardancy properties in a concept of sustainable material management.

In recent years, there has been a growing interest in many parts of the world for more effective biomass utilization due to legislative and public interest in sustainable development. Whilst much of the effort has been on energy generation from biomass, there is considerable interest on biomass availability and utilization for other end uses. With about 1% of the world's commercial forest areas, Sweden provides about 10% of the sawnwood, and pulp and paper that is traded on the global market. The Swedish agricultural sector also contributes to biomass availability, not only by production of sustainable food crops, but also by utilizing side streams and underutilized land for biomaterial purposes. To meet the challenges that climate change presents, there has to be a shift to sustainable biomass production and increased interest in promoting a circular bioeconomy.Waste and Biomass Valorization 1 3 utilization by the Swedish forest products industries, including biorefineries within the Swedish context.

IntroductionIt is well established that chemical modification of wood using anhydride reagents results in volume increases of the substrate, and imparts dimensional stabilisation (e. g. Stamm and Tarkow 1947;. Various studies of the relationship between the swelling of the material due to modification have been published. For example in studies of the acetylation of spruce, maple and balsa, it has been found that the degree of swelling of the substrate exhibits a proportional relationship with the degree of substitution, up to an acetyl content of 16-18 % (Stamm and Tarkow 1947). Furthermore, the volume increase due to modification has been found to be equal to the volume of the acetyl groups in the wood (Stamm and Tarkow 1947;Rowell and Ellis 1978).Recently, the observation that degree of swelling due to modification is equal to volume of adduct has been challenged (Hill and Jones 1996 a), where it has been found that for Corsican pine modified with linear chain anhydrides a volume increase larger than theoretically predicted is obtained. This deviation is particularly pronounced at lower weight percent gains (wpg's). The volumetric swelling of wood due to esterification has been studied, and the effect of such modification upon the dynamic mechanical properties of wood determined (Nakano 1988;Nakano 1994). In this work, it was considered that volume increase of the wood (V) was the sum of volume occupied by reagent (V i ), plus a void volume (V f ) created in the cell wall polymeric network. With this particular system, a linear relationship was found between V i and V f which correlated with the chain length of adduct.In order to further the understanding of the nature and source of volumetric changes occurring in wood due to anhydride modification, a study has been performed to determine the effect of chemical modification with an homologous series of linear chain anhydrides ( Fig. 1: acetic (R = CH 3 ), propionic (R = C 2 H 5 ), butyric (R = C 3 H 7 ), valeric (R = C 4 H 9 ), hexanoic (R = C 5 H 11 ), or heptanoic (R = C 6 H 13 ) anhydride) upon Corsican pine (Pinus nigra) sapwood. The results of this study are reported herein. Materials and MethodsSawn blocks of Corsican pine sapwood (20 mm x 20 mm x 5 mm: radial x tangential x longitudinal) were subjected to Soxhlet extraction for 8 hours using a solvent system composed of toluene: methanol: acetone (4 : 1 : 1, by volume), then oven dried at 105°C for 12 hours. Samples were pre-selected such that growth rings were parallel to the tangential face. Prior to modification, samples were transferred to a vacuum dessicator, allowed to cool to room temperature, weight determined on a four figure balance, and dimensions measured using a micrometer (accurate to +/-0.01 mm). Wood samples were modified using an identical procedure for each anhydride, to a variety of wpg's ranging from 0.5 % to 35 %, the only exception being acetic anhydride where wpg's above 25 % were not obtained. At least 20 different wpg's were obtained for each anhydride. For modification, sample...

To be useful for policy and decision making, indicators should be developed around sound conceptual frameworks and should encompass multiple aspects of institutional or system performance.