Evaluation of Polyvinyl Alcohol Size Pick up on Flax Fibers
Optimal PVA size pick-up on flax warps ranges from 8.0 to 9.0 percent dry weight, balancing yarn friction resistance with hot-water desizing washability.
Hydrolysis Level
Extraction Metric
Chemical extraction monitoring in yarn preparation employs a numerical value to represent the proportion of non-cellulosic compounds removed during treatment. In linen bleaching and refining, hydrolysis level defines the extent of polymer breakdown in the pectin-rich middle lamella. This value is calculated by analyzing the weight loss of a sample or by measuring the concentrations of dissolved sugars in the waste bath.
Mill technicians rely on this measurement to ensure the consistency of successive batches.
Process Impact
Inadequate processing leaves the material coarse and unspinnable. When the hydrolysis level is too low, the thick bundles cannot be drafted into fine yarns. The resulting thread exhibits high irregularity and frequent slubs.
Such yarn is unsuitable for high-quality weaving and must be downgraded to coarser utility fabrics.
Quality Threshold
Over-processing poses a severe threat to the physical integrity of the cellulose chain. A high hydrolysis level weakens the individual filaments by degrading the crystalline areas of the fibre. This damage shows up during wet spinning as a sudden increase in breakages and high waste generation.
The spinning shop logs the value for every treated roving lot to confirm that the material meets the buyer’s yarn strength specification before commencing large-scale production. If the value exceeds the limit, the lot is redirected to coarser counts where tensile strength is less critical.