Virgin Hardwood Pulp Sizing Chemistry and Fibre Hydrogen Bonding Properties
Virgin hardwood sizing requires balancing high surface hydroxyl density against AKD and ASA steric interference to maintain internal bond and Cobb holdout.
Xylan Content
Hemicellulose Fraction
Chemical composition analyses quantify the pentosan hemicellulose percentage present within wood pulp fibers used for papermaking. Xylan content measures the concentration of xylose-based polymers remaining in kraft or mechanical pulps after chemical digestion. Retention of this carbohydrate polymer influences fiber swelling, beatability, and mechanical sheet strength during paperboard manufacturing.
Alkali Extraction
Hardwood species contain higher levels of xylan than softwood species, making xylan concentration a primary marker for wood species identification in pulps. Xylan content directly affects fiber flexibility and interfiber bonding capability during web consolidation on the paper machine. Hydrophilic xylan molecules absorb water during refining, causing fibers to swell and develop higher specific surface area for hydrogen bonding.
Higher xylan retention improves tensile strength and burst strength while reducing mechanical refining energy consumption. Chemical pulp mills control cooking liquor alkalinity and washing stages to preserve xylan structures during kraft pulping. Laboratory analysis quantifies xylan using high-performance liquid chromatography or acid hydrolysis followed by gas chromatography.
Yield Threshold
Chemical carbohydrate profiling evaluates hemicellulose retention in chemical and mechanical pulps. Xylan content measurement does not apply to non-cellulosic synthetic fibers or fully regenerated cellulose films. Chemical tracking stops once pulp undergoes complete nitration or acetylating reactions.
Analytical accuracy decreases when sample degradation occurs during acid hydrolysis.