Durable Press Finishing Of Cotton Fabrics With Polycarboxylic Acids

In this paper a detailed investigation was carried out to elucidate the effects of a non-formaldehyde polymerization-crosslinking treatment on the performance properties of 100% cotton fabrics. The fabric samples were treated with unsaturated dicarboxylic acid(s) (maleic acid (MA) and/or itaconic acid (IA)) in the presence of polymerization initiator and esterification catalyst. It is believed that long chain polycarboxylic acids can be produced by addition polymerization of monomer(s). Subsequently these newly formed polymers react with cotton cellulose at elevated temperature to form ester-type crosslinks with cellulose molecules to obtain the finishing effects.The effects of parameters such as monomer and initiator concentration, temperature and duration of drying and curing, and catalyst concentration were explored in this study. The treated fabric samples were evaluated in terms of retention of mechanical properties and improvement of wrinkle recovery angle to determine a suitable finishing process. Performances of cotton fabrics treated with MA/IA or MA polymerization-crosslinking method were compared to those treated with citric acid (CA). The results demonstrate that the system of a 1:1 molar ratio of MA and IA substantially increases wrinkle resistance while maintaining much improved strength retention of the treated fabric. The finishing effects of steam process were compared with the conventional process, and it appears that steam drying or curing does not contribute to the improvement of the fabric strength retention.The strength retention of the treated fabric can be further improved when moderate amount of reducing agent is added in the finishing bath to form an oxidizing-reducing system with the initiator. This is probably due to the factor that reaction rate can be improved by the oxidizing-reducing system.The study has also examined the effect of using various potential additives. The performance of treated fabrics can be further increased by adding moderate amount of triethanolamine (TEA) or polyols. Take TEA as an example, strength retention, durability on washing and whiteness of the treated fabric can all be improved. To investigate the probable cause of such improvement, cotton fabrics were treated with two finishing baths containing TEA or NaOH, respectively. The introduction of NaOH in the treatment bath was to adjust the pH value to the same as the bathcontaining TEA. The amount of ester-linkages formed on treated fabrics, the wrinkle recovery angle and tensile strength retention of treated fabrics were determined and compared. For the TEA-treated samples, the ester-linkage content was greatly improved, while the wrinkle recovery angle only slightly increased. Thus, it seems that hydroxyl groups of TEA react with carboxyl groups to form ester-linkages and even flexible network structure, which leading to the improvement of the strength retention and washing durability of treated fabrics.The home laundering tests show that for the MA/IA-treated fabrics, the amount of free carboxyl groups decreases more greatly than the ester-linkages. Therefore, it can be concluded that ester-attachments were more ready to hydrolysis than ester-crosslinkings, and that MA/IA-treated fabrics exhibit good washing durability. The results are similar to the case of BTCA in literature.The reaction kinetics and activation parameters of MA/IA or MA in-situ polymerization-crosslinking treatment have been determined by measuring the unreacted portion, respectively. Values for Arrhenius energy (Ea) and rate constant (k) can be used to explain the performances of fabrics treated with different finishing baths. For both polymerization and esterification, the activation energy for MA treatment is higher than that for MA/IA. Enthalpies, entropies, and Gibbs free energies of activation of the systems were also calculated. In addition, infrared spectrum analysis was utilized to extrapolate during which stage the reaction occurs according to the changes in the functional groups in cellulose.To further elu...