J. Gacén

Viscoelastic Behaviour and Microstructural Modifications in Acrylic Fibres and Yams as a Function of Textile Manufacturing Processing Conditions

Tensile tests on acrylic yarns and fibres extracted from various steps of textile processing reveal mechanical and thermal modifications due to the manufacturing operations. To examine this, viscoelastic modelling based on mechanistic models for fitting experimental data of tensile tests were investigated. Crystalline/amorphous distribution was assessed by the differential solubility technique, and the models account for changes in property values due to microstructure modifications.

Physico-chemical Analytical Techniques for Evaluation of Polyester Heatsetting

A polyester fabric has been heatset in an industrial plant over a wide range of temperatures (160–220°C) to study the influence of this variable in the modification of the fine structure produced by this thermal treatment. For this purpose, the weft of the fabric has been characterised through physico-chemical tests such as critical dissolution time, differential solubility and iodine sorption. The heatsetting effective temperature has been determined by differential scanning calorimetry and the crystallinity calculated from density measurements in a density gradient column. Both parameters have been correlated. The fine structure parameters deduced from the above mentioned techniques have been correlated with the effective temperatures of heatsetting.

Differential solubility of cellulosic man-made fibres

The differential solubility of man-made cellulosic fibres in zinc chloride/formic acid dissolutions has been studied. This technique of characterisation of the fine structure has been applied to substrates of different families of cellulosic man-made fibres such as viscose (staple and filament), modal, polynosic and lyocell fibres. The developed technique has allowed the detection of the fine structure differences in substrates of different families of man-made cellulosic fibres, and even in substrates of the same family and/or form of presentation (staple fibre, filament yarn).

Differential Solubility of Acrylic Fibres as a Function of Stabilisation Process Variables

Acrylic tow, partially relaxed during the first stage of a conventional manufacturing process, was fully relaxed, or stabilised, in steaming equipment under different conditions of time and temperature based on a central rotatable design of experiments. The shrinkage of the samples thus obtained was measured and differential solubility curves in a mixture of dimethy/formamide and water were obtained. From these results simple functional relationships between shrinkage and solubility on the one hand, and the process variables, temperature and time, have been obtained. Response surfaces showing an excellent fit have also been obtained. A very good negative linear correlation between the logarithm of shrinkage undergone during steaming and the logarithm of differential solubility, and also between the logarithms of overall shrinkage and differential solubility have been found. The differential solubility test has a very high sensitivity to relaxation process variables and, as shown by the correlations obtained, it is highly recommendable as a relaxation control measure in production plant.

Micromorphology Differences between Relaxed and Retractile Acrylic Fibres Subjected to Different Bulking Treatments

Three commercial acrylic fibres from different manufacturers were employed in preparing 100% relaxed (N), 100% retractile (R), 45% N/55% R, and 55% N/45% R substrates. These were subjected to different bulking treatments (boiling water for periods of 15, 30, and 90 min and dry heat). The resulting substrates were tested for differential solubility in a blend of dimethylforamide/water to study their micromorphological evolution.