A novel carrier dyeing strategy to improve the strength and comfort performance of the polyimide fabrics

The loss of strength and poor handle are two prominent problems that impede the practical application of dyed polyimide fabrics in protective clothing. To address this issue, an environmentally friendly glycerol–water solvent system was employed to replace the pure water solution in conventional carrier dyeing, taking advantage of the specific viscous and solubility properties of glycerol. Through various characterisations, it was demonstrated that the addition of glycerol leads to two effects: decreased diffusion of the dyeing solution and a higher dye concentration to size ratio in the water and phenoxyethanol phases. Resulting from the combination of these effects, the K/S in the glycerol–water mixture is initially enhanced compared with that for the conventionally dyed sample, followed by a decrease as the amount of glycerol is increased. When the volume ratio of glycerol to water is 4:2, the K/S remains the same as that calculated for the conventionally dyed sample. By contrast, a surprising improvement was observed in tensile strength, as well as the breathability and softness of the dyed fabrics in the glycerol–water system. Specifically, in comparison with the conventionally dyed sample, there was an increase of 31.4% in tensile strength, 63.6% in breathability and 125% in softness under the volume ratio of 4:2, which can mainly be ascribed to the decreased penetration of carrier and water, leading to less swelling and hydrolysis.