Design and Preparation offilms from Birchwood Xylan

Sammanfattning: Using and finding applications from biomass is and will continue to be an important subject forresearch, and biomass from trees, has shown several outstanding aspects other than just for the pulpand paper applications. It is now, more than ever, time to find efficient uses for all the woodcomponents, in particular, the hemicelluloses. The hemicelluloses account for approximately onethirdof a dry composition of lignocellulosic wood biomasses. Of these hemicelluloses, xylan is themost abundant in many plants, particularly in hardwood. As for the Swedish forestry, xylan frombirch is considered as one of the most promising resources for the future.This thesis investigates the impact of acetylation of xylan on some properties such as solubility,thermal stability and film formation. Films were prepared using the non- and acetylated xylan withaddition of different plasticizers (glycerol, sorbitol and xylitol).Alkali-soluble birch xylan (ASX), obtained by ethanol/toluene extraction and sodium chloritedelignification of the wood sawdust followed by potassium hydroxide extraction of the obtainedholocellulose, and commercial xylan (CX) were acetylated to different degree of substitution withacetyl groups (DSAc), using acetic anhydride in dimethyl sulfoxide (DMSO) and 1-methylimidazole(NMI). Films were prepared by suspending non-acetylated xylan in water (H2O) and adding differentpercentages of plasticizers (20 and 40%) or by suspending acetylated xylan in chloroform (CHCl3).Characterizations of the non- and acetylated polymer (AcASX and AcCX) and films were conducted inorder to determine thermal and mechanical properties.CX and ASX presented different reactivity leading to different behaviour during acetylation and sodifferent DSAc. The thermal stability has been improved for both ASX and CX following the increase ofthe DSAc. Concerning film formation, ASX showed a great ability to form films through casting with orwithout plasticizers while it was impossible to obtain any films using only CX. For AcASX and AcCX thefilm formation using chloroform was depending on the DSAc and the dispersability in the solvent. Allthe films obtained have been mechanically and thermally tested. Best results for the mechanicaltests were obtained with 40% plasticizers with creation of a plastic behaviour and improvement ofthe flexibility. Thermally speaking, the thermal stability gained through acetylation of the samples islost by film casting, and use of plasticizers reduced the thermal stability as a new component wasadded to the composition.