Study On The Preparation And Sensing Properties Of TPU Based Electrospun Fibers

Research on the external field stress response behavior of flexible conductive polymer composites has been a research hotspot in recent years.In this paper,thermoplastic polyurethane(TPU)is used as the polymer matrix and conductive graphite as the conductive filler.The flexible conductive composite fiber with adjustable diameter is prepared by the solvent flocculation-melt electrospinning method.The effect of the spinning process parameters on the fiber diameter is studied.Meanwhile,researching affect the stress response ability,electrical resistivity,elongation at break and hydrophobic properties of conductive graphite/TPU composite fibers under different loadings is necessary.The research results of spinning process parameters on fiber diameter show that spinning voltage is the dominant factor of fiber diameter,and the diameter will decrease monotonously with the increase of voltage.The elongation at break of the fiber is significantly affected by the diameter and the filling amount.The elongation at break first increases and then decreases with the increase of the diameter.When the diameter is 0.7mm,the maximum elongation at break can reach 435%.Hydrophobic characteristics and line resistivity are mainly affected by the amount of filling.The contact angle increases with the increase of the filling amount,which can be increased from 77.23° to 102.4°.The line resistivity can be as low as 3%graphite filling amount 1.412×1012Ω·cm.The results of stress response test show that the maximum linear correlation and sensitivity coefficient of fiber resistance are 99.48%and 6.36,respectively,in the range of 0-140%tensile deformation test.At 30-80℃,the fiber’s temperature-sensitive response is linear in stages.The maximum value of the sensitivity coefficient is 3.3%and 0.81%in two linear ranges,and the response time is 13s and 12s,respectively.In addition,with the increase of test cycles,the hysteresis coefficients of tensile and temperature-sensitive responses decreased by 83.5%and 90.6%,respectively.This study shows that graphite/TPU composite fibers have higher sensitivity and faster response time to linear tension and temperature disturbance,and the sensing characteristics are significantly affected by spinning voltage,filling ratio and filling graphite size.The linear response of the fiber conforms to the theory of conductive network,while the nonlinear response curve conforms to the model of tunneling effect,which has a good application prospect.