Quantification of water in different states of interaction with wood pulp fibres

Experimental techniques for characterising water in wood covering the range from dry to fully water-saturated

“…This type of equipment measures the energy involved in changing the temperature of a small sample over a wide temperature range. The amount of sample depends on the geometry of the crucible of the specific DSC instrument, but typical sample masses and sizes are in the range 5-15 mg (Park et al 2006;Weise et al 1996) and 1-mm discs of 3-4 mm diameter (Simpson and Barton 1991;Zauer et al 2014), respectively. The technique is particularly useful for determining the energy involved in exothermic or endothermic reactions occurring during an experiment, for example phase transitions such as freezing or thawing of water.…”

“…This was first used by Magne et al (1947) to determine the amount of cell wall water in water-saturated textile fibres (cotton, rayon, nylon, glass fibres) by measuring the energy for freezing water at -4°C. Since then, DSC techniques have been used to determine cell wall water within, for example, pulp and paper fibres (Maloney 2000;Nelson 1977;Park et al 2006;Weise et al 1996), untreated wood (Simpson and Barton 1991;Zauer et al 2014;Zelinka et al 2012), and modified wood (Repellin and Guyonnet 2005;Zauer et al 2014). By cooling or quenching a wet sample to a given sub-zero temperature and ramping the temperature at constant rate to a specified temperature above the freezing point of water, the energy input (enthalpy) required to melt the ice formed can be measured.…”

“…By cooling or quenching a wet sample to a given sub-zero temperature and ramping the temperature at constant rate to a specified temperature above the freezing point of water, the energy input (enthalpy) required to melt the ice formed can be measured. Temperature ranges and ramping rates employed vary between studies, but are most often found within the -40 to 40°C range (Park et al 2006;Repellin and Guyonnet 2005;Simpson and Barton 1991;Weise et al 1996;Zauer et al 2014) and from 1 to 3°C/min (Park et al 2006;Repellin and Guyonnet 2005;Weise et al 1996;Zauer et al 2014) to 5°C/min (Zelinka et al 2012) or even 10°C/min (Nelson 1977;Simpson and Barton 1991) [-] corrects for mass gain due to modification if present. If the sample is fully water-saturated, MC cell-wall corresponds to FSP, and using such samples avoids problems of non-saturation of any parts of the wood volume examined.…”

Proposed Nano-Scale Coalescence of Cellulose in Chemical Pulp Fibers During Technical Treatments

“…However, the fiber saturation point (FSP) changes drastically at temperatures above 70 °C. This is probably due to the increased removal of water between the microfibrils or the increase in molecular rearrangements at temperatures above 70 °C (Weise et al 1996). The capillary pressure in a porous system is also said to be enhanced by increasing temperature (Hanspal and Das 2012).…”

Recycling Effects on the Properties of Pulp Fiber Sheets Produced from Oil Palm Empty Fruit Bunch

“…After three recycling treatments, however, the largest hornification value was associated with the EFB soda pulp and the second largest for the EFB kraft pulp. This may be explained by considering that, as delignification occurs during cooking of the wood fiber cell walls, areas where lignin and hemicellulose were present become voids, forming a lamellar structure [8]. During recycling, these lamellae attract one another due to dehydration and irreversible intrafiber hydrogen bonds are continuously formed between cellulose protofibrils.…”