Resolving Non Target Solvent Attack Dynamics in High Temperature Cellulosic Separations
Maintaining solvent moisture at 13.0 percent and temperatures below 108°C prevents non-target synthetic polymer breakdown during cellulosic extraction.
Polyester Hydrolysis
Degradative Hydrolysis
Chemical reactions with water cause the breakdown of the ester linkages in synthetic polymer chains. Polyester hydrolysis occurs most frequently in hot and humid environments, leading to a loss of tensile strength and increased brittleness. This process is accelerated by the presence of acids or alkalis that act as catalysts during the reaction.
Moisture Absorption
Synthetic fibres generally resist water, but the small amount that penetrates the polymer matrix can cause internal damage. Under high pressure and temperature, such as in a pressure dyeing machine, polyester hydrolysis proceeds rapidly if the pH is not strictly controlled. The water molecules insert themselves into the ester bonds, splitting the chain into an acid and an alcohol.
This reaction creates new acidic end groups that further catalyze the process, leading to a rapid decline in the molecular weight of the polymer.
Quality Inspection
Laboratories assess the damage by measuring the increase in carboxyl end groups in the polymer. As polyester hydrolysis advances, the viscosity of the dissolved polymer drops, indicating a decrease in molecular weight.
Prevention Strategy
Additives known as hydrolysis stabilizers are incorporated into the polymer melt to extend the life of the material. These chemicals react with the acidic byproducts of the reaction to prevent further autocatalytic breakdown. Ensuring that the fabric is completely dry before high temperature processing also minimizes the risk of hydrolysis.