Alkaline Hydrolysis Kinetics and Carbohydrate Retention in Continuous Digesters
Controlling effective alkali profiles and temperature in continuous digesters maximizes xylan retention, stabilizing pulp yield and securing compliance files.
Intrinsic Viscosity
Polymer Measurement
Limiting viscosity number measurements of dissolved pulp in a specific solvent provide an estimation of the average chain length of cellulose molecules. Evaluating the intrinsic viscosity of the cellulose helps pulp manufacturers determine the degree of polymer degradation during bleaching and cooking. Severe chemical treatment cleaves the cellulose chains, which decreases their molecular weight and reduces the strength of the resulting paper fibres.
This measurement provides a quality control metric for specialty dissolving pulps and papermaking grades.
Laboratory Standard
Measurement protocols involve dissolving the pulp sample in a dilute solution of cupriethylenediamine hydroxide at twenty-five degrees Celsius. The efflux time of the solution through a calibrated capillary viscometer is measured and compared to the flow time of the pure solvent. Calculations using the flow ratio yield the specific viscosity, which is then extrapolated to zero concentration to obtain the final value.
This test requires precise temperature control and the exclusion of oxygen to prevent autoxidation of the dissolved cellulose.
Pulp Evaluation
High viscosity values correlate with superior tearing resistance and tensile strength in the finished sheet. When intrinsic viscosity drops too low, the paper becomes brittle and fails during high speed converting or printing runs. Papermakers use these measurements to optimize their bleaching sequences.