Now You Know Determination of the Degree of Heat Setting
Tuesday 22 January 2019
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Determination of the Degree of Heat Setting
Rana Sohel
Executive Engineer
Sunman Textile Mills Ltd. Chittagong
Cell: +8801912-420118
Email: rsohel07tex@gmail.com
Executive Engineer
Sunman Textile Mills Ltd. Chittagong
Cell: +8801912-420118
Email: rsohel07tex@gmail.com
Heat setting:
Heat setting is a thermal process which is applied in textile industry. It is done for shape retention, crease resistance, resilience and elasticity are imparted to the fibres. The effect of the process gives fibers, yarns or fabric dimensional stability and, very often, other desirable attributes like higher volume, wrinkle resistance or temperature resistance. It also brings changes in strength, stretch ability, softness, dye ability and sometimes on the color of the material.
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| Heat setting of Lycra fabric by stenter |
1. Shrinkage test
Normally a square area is drawn on the heat-set material and measured. The marked cloth is boiled in soft water in the washing wheel for 30 min, centrifuged and air dried. The dimensions of the square are measured without ironing the dried fabric and the shrinkage is determined. A well set fabric should not show more than 1% residual shrinkage.
2. Crease-recovery angle
The determination of crease recovery angle before and after heat-setting of the fabric is done. The extent of crease-recovery of heat-set fabric before and after setting at and above 170-175 will give idea of the degree of heat-setting.
3. Assessment of handle
Assessment of handle before and after setting gives an idea of the degree of heat-setting. In general, fabric becomes stiff after heat-setting. Stiffness is measured by bending length and compared with that of the unset fabric. The narrower the difference of bending length between the set and unset fabrics, the better the setting.
4. Iodine absorption method
The degree of heat-setting of polyester fabrics can be correlated with their iodine absorption value. Heat-setting under industrial conditions in a taut form reduces the amorphous content of synthetic fibers. So, there will be a decrease in iodine sorption and increase in critical dissolution value.