Testing Standard
International analytical methods establish standardized chemical extraction protocols to evaluate the chemical purity of dissolving wood pulp before fiber extrusion. Compliance with iso 2116 defines the percentage of pulp soluble in sodium hydroxide solutions of specific concentrations at twenty degrees Celsius. High alkali solubility indicates elevated degradation of cellulose chains, which adversely affects yarn tenacity and viscose filament filtration.
Mill laboratories test incoming dissolving pulp bales against supplier specifications to ensure spin bath compatibility.
Dissolving Procedure
Chemical extraction measures low molecular weight hemicelluloses and degraded short chain cellulose fractions. Testing under iso 2116 exposes pulp specimens to eighteen percent and ten percent sodium hydroxide solutions for one hour under controlled temperature conditions. The insoluble residue is isolated by filtration on glass fiber filters, washed, dried, and weighed to calculate total dissolved mass fractions.
The remaining liquor is oxidized with potassium dichromate to quantify soluble organic material by titration.
Degradation Metric
Quantitative solubility ratios reveal the degree of polymer degradation suffered during wood pulping and bleaching. Under iso 2116 testing, S18 values quantify non-cellulosic hemicellulose content while S10 values capture both hemicellulose and short degraded cellulose chains. The numeric difference between S10 and S18 establishes the exact proportion of degraded short chain cellulose present in the pulp sample.
Application Boundary
Analytical extraction results apply strictly to raw cellulose pulp before chemical conversion into viscose staple or filament. Testing under iso 2116 cannot evaluate final yarn quality, crosslinking density, or fabric physical properties post-extrusion. Reagent concentration variations or temperature deviations outside the twenty degrees Celsius setpoint alter solubility rates and invalidate comparative batch analysis.
