Mechanical properties of long carbon chain polyamide 1012 fiber at different temperature fields
Objective Preliminary industrial spinning trial suggested that long carbon chain polyamide 1012(PA1012)has good spinning performance.In order to further explore the application possibility of PA1012 fiber in the environment of extremely low and high temperatures,tensile mechanical property evolution of PA1012 fully-drawn yarn(FDY)and drawn and textured yarn(DTY)with different drawing ratios at different temperature fields were investigated.Method PA1012 resin chips were used as raw materials to prepare PA1012 FDY and DTY samples using a melting spinning machine.Differential scanning calorimetry(DSC)was adopted to test the basic thermal properties,and the dynamic thermomechanical properties of PA1012 fiber were analyzed by dynamic mechanical analysis(DMA).The tensile mechanical property evolution of PA1012 FDY and DTY with different drawing ratios of 1.3-2.7 at different temperature fields were investigated by universal testing machine and X-ray diffraction instrument.Results The glass transition temperature and melting temperature of PA1012 fiber were 65.6 and 188℃,respectively.The DMA test results revealed three loss peaks with different intensities appearing at 70.9,-3.6 and-56.0℃,corresponding to the α,β and γ relaxation of the PA1012 fiber(Fig.2).At room temperature,the tensile mechanical properties of PA1012 FDY with different drawing ratios were found similar.With the increase of tensile elongation,the tensile strength of PA1012 FDY showed a linear increase.When drawing to the yield point,a tensile platform area appeared,and showed that the higher the drawing ratio the shorter the platform area.As the tensile elongation increasing,the tensile strength continued to increase until fracture appeared(Fig.3).Furthermore,the initial modulus,yield strength,yielding elongation and breaking strength of PA1012 FDY demonstrated a positive linear correlation with the drawing ratio,and the breaking elongation correlated with the drawing ratio in a negative exponential relationship(Fig.4).By contrast,the initial modulus of DTY1.3(the drawing ratio of 1.3)at room temperature decreased by 57.47%,and the average breaking strength decreased by 2.24%,but the breaking elongation increased by 1.40%(Fig.5).These were resulted from the texturing action decreased the crystallinity and axis orientation index of PA1012 fiber(Fig.6 and Tab.3).With the increase of the extreme ambient temperature,the initial modulus,yield strength,and breaking strength PA1012 FDY with different drawing ratios gradually decreased,and the yielding elongation was substantially unchanged.However,the breaking elongation increased significantly(Fig.7).Furthermore,the experiments found that the breaking strength of PA1012 FDY2.7(the drawing ratio of 2.7)at-70℃was high and reached 6.04 cN/dtex,with the breaking elongation of 9.13%.PA1012 FDY with different drawing ratios became brittle at-70℃,with no yield when stretched.When increasing the extreme temperature,the initial modulus and the breaking strength of PA1012 DTY1.3 demonstrated gradually decreases,but the breaking elongation appeared to increase significantly.Conclusion PA1012 FDY has potential application prospects in polar cold regions as-70℃.PA1012 FDY with different drawing ratios are suitable for different high-temperature limits.PA1012 FDY1.3 and PA1012 FDY1.7(the drawing ratio of 1.7)can be used in the extreme environment temperature range from-70℃to 120℃.However,with the further increase of the drawing ratio,the limit high temperature suitable for using PA1012 FDY shows a downward trend,and the environment temperature for using PA1012 FDY2.1(the drawing ratio of 2.1)and PA1012 FDY2.7 should not exceed 60℃.PA1012 DTY1.3 can be used normally in the environment temperature range from 0℃to 120℃,but it is not suitable for using in a low temperature environment below 0℃.It can be seen that by adjusting the drawing ratio of PA1012 FDY,the prepared PA1012 fibers can obtain good mechanical properties in different environments of extreme high and low temperature,and adapt to the actual applications in polar cold regions and high hot environments.
long carbon chain polyamide 1012 fiberfully-drawn yarndraw and textured yarndrawing ratiotensile mechanical propertyextreme environment
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