Pectin Thermal Degradation Kinetics during Bast Fibre Moisture Conditioning
Thermal pectin depolymerization degrades flax middle lamellae above 70°C, lowering bundle tenacity and forcing coarse count downgrades.
Bast Fibre Hydrolysis
Reaction Mechanism
Chemical treatment of plant material involves the breakdown of non-cellulosic polymers in water at elevated temperatures. In the preparation of linen yarns, bast fibre hydrolysis represents the controlled cleaving of pectin and hemicellulose that bind individual fibres together. The reaction is driven by acidic or enzymatic agents in a liquid bath.
Degradation Risk
Thermal and chemical parameters in the scouring stage determine the yield of the spinnable material. Excessive bast fibre hydrolysis reduces the structural integrity of the cell walls, resulting in weakened fibres that break during subsequent carding and drafting. The degradation can be monitored by measuring the weight loss of the treated charge.
Mill laboratories establish strict limits for treatment times to prevent cellulose damage.
Processing Limit
Acceptance criteria for the treated roving demand a specific compromise between fiber fineness and tensile strength. When bast fibre hydrolysis is halted too early, the remaining gum makes the material too stiff for wet spinning, which causes uneven yarn thickness. Conversely, over-processing yields an overly soft roving that lacks the cohesion needed to withstand the tension of the spinning frame.
Chinese mills typically test the residual pectin content to verify that the extraction has reached the optimum threshold. This quality gate is documented in the batch processing card before the wet-spinning room accepts the lot.