ABSTRACT:The structural and thermal behaviors of polyester yarns treated with trichloroacetic acid-chloroform (TCAC) mixture were investigated by differential scanning calorimetric analysis (DSC), wide-angle X-ray scattering (WAXS), infrared spectroscopy (IR), and scanning electron microscopy (SEM). The effects of TCAC treatment on original fine filament (FFP) and microdenier (MDP) polyester yarns and on heat-set polyester yarns were studied. It was found that the glass transition temperature of TCAC-treated polyester yarns decreases with an increase in treatment concentration due to the plasticization effect, which is remarkable even at lower treatment concentration. The TCAC treatment on polyester yarns resulted in the formation of new crystallites in the extended noncrystalline domains of PET as well as growth and perfection of these new crystallites and the preexisting crystals. Further, the DSC thermograms revealed that TCAC treatment with 3% concentration could be able to overcome the structural changes in PET produced by heat setting at 180°C. The substantial changes in noncrystalline and crystalline domains observed were related to the mechanical properties of yarns. From the WAXS studies, an increase in crystal size and lateral order of TCAC-treated polyester yarns was noted. The most distinct changes brought about by TCAC treatment include overall orientation determined by the trans-gauche ratio from IR measurements. The removal of oligomers and smoothening out of the fiber surface by TCAC treatment were observed from SEM studies.

ABSTRACT:The mechanical properties of polyester (PET) yarns, fine filament, and microdenier (original and heat-set), treated with a trichloroacetic acid-chloroform (TCAC) mixture were investigated. The treatments were carried out in an unstrained state with various concentrations of the TCAC reagent at room temperature. The TCAC treatment on PET yarns resulted in notable changes in the tensile behavior. The TCAC-treated yarns exhibited higher extensibility and work of rupture without much loss in strength. The improvement in elongation was less in the case of heat-set polyester yarns due to solvent treatment. The depression of the glass transition temperature (T g ) of TCAC-treated PET yarns, even at the minimum concentration, showed its effectiveness to plasticize the fibers and the closeness of the solubility parameter of TCAC and PET. The T g depression favors molecular relaxation, which has resulted in a higher shrinkage percentage of TCAC-treated PET yarns and the effective shrinkage was reached more easily for the original fine-filament polyester (FFP) and microdenier polyester (MDP) yarns at the lowest concentration. The effects of the concentration of TCAC on the strength, elongation, yield behavior, and work of rupture on PET were also investigated. A significant plastic flow was observed in the TCACtreated yarns.

A single stage, low temperature scouring/bleaching process has been investigated, based on an emulsified solvent scouring agent and a triethanolamine hydrochloride activated sodium chlorite bleaching agent. The optimization uses response surface methodology. It is possible to scour and bleach cotton fabric at 60°C with sodium chlorite.

Optimisation of a low‐temperature combined scouring and bleaching process for polyester/cotton fabric using triethanolamine hydrochloride‐activated sodium chlorite as bleaching agent and a self‐emulsifiable solvent composition as scouring agent has been carried out. The effect of various parameters, namely bleaching agent concentration, time and temperature of treatment, has been investigated by a factorial design methodology.

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