Abstract
The thermal stress on a hydrophilic filament consists of the thermal stress caused by the partial decrease of frozen strain and the contractive stress due to the loss of moisture within a filament during heating.
We investigated the variation of the thermal stress on 6-nylon filament, as an example of hydrophilic fiber, due to the relative humidity in the closed vessel covering apparatus.
The results obtained are as follows;
1) Decreasing the initial relative humidity of closed vessel, the thermal stress curve on 6-nylon (hydrophilic) filament approaches to that on P. P. (hydrophobic) mono-filament.
2) Though the thermal stress on 6-nylon mono-filament is superposed by drying stress, there is a linear relation between the maximum stress (Fmax) in high temperature region and its temperature (Tmax) in each relative humidity.
Therefore, it may be considered that the setting conditions on sample are not influenced by the amount of moisture within the sample.
3) Increasing the elongated percentage of samples, the peak (or shoulder) in low temperature region on the thermal stress curve of 6-nylon momofilament which is related to moisture content shiftes to the higher temperature.
4) The secondary yield point on the stress strain curve of 6-nylon mono-filament corresponds to the peak in high temperature on the thermal stress curve, and these points are independent of the moisture content within the sample.
While, the first yield point on stress-strain curve of the sample corresponds to the peak (or shoulder) in low temperature region on the thermal stress curve, and increasing the relative humidity, the peak (or shoulder) in low temperature region increases its height and conversely first yield point decreases.
