The Dimensional Stabilisation of Corsican Pine Sapwood by Reaction with Carboxylic Acid Anhydrides. The Effect of Chain Length

Abstract

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. It 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.