Analysis on mechanical properties and fracture morphology of Xinjiang long-staple cotton fiber
Objective The paper aims to reduce the mechanical damage of long staple cotton caused by during mechanical processing.Exploring the changes of physical properties and morphological transition under different mechanical process parameters.Method The tensile test of long-staple cotton fiber was conducted on tensile tester,and the mechanical properties and morphological changes of fiber samples during the tensile process were analyzed.The test temperature was(21±2)℃and the relative humidity was(65±5)%.The influence of fiber diameter,specimen length and tensile speed on the mechanical properties and morphological changes was investigated using a single factor method.The response surface regression model of the interaction of three factors was analyzed and established by the response surface method.The morphology of cotton fiber fractures with different fracture methods was analyzed by scanning electron microscopy.Results The breaking strength decreased gradually with increasing diameter when the length and tensile speed of cotton fibers remain unchanged.It was found that the diameter and surface morphology are related to the maturity of the fibers,the breaking strength increased with the increasing tensile speed for the same diameter,and minor defects appeared along the tensile direction.As the load further increases,the cracks gradually growth due to a large number of defects accumulated and leading to fiber breakage.The tensile speed and length of fiber have a great influence on the fracture strength,the breaking strength of fiber increases with the increase of tensile speed while decreases with the increase of length.The breaking strength is 38.48 mN for the length of 1 mm and tensile speed of 2 μm/s,and 52.63 mN for the speed of 6 μm/s.The mechanical properties of fibers affected by the three factors mentioned above,and the interaction of them in the order of fiber diameter＞tensile speed＞sample length.When the load is small during the stretching process,the break elongation and tensile speed of fibers did not have much effect,but both of them increased as the sample length increasing.Furthermore,the two forms of breakage of cotton fibers during stretching often occur.One is that the fiber tension increases with stretching and suddenly breaks when it reaches the maximum bearing tension of cotton fiber.The second is that the tensile force increases firstly to the peak value,then suddenly drop to a certain tensile force and continue for a period of time and then drop to zero.The load-tension curves of fibers showed direct and gradual fracture during stretching,which was related to the initial morphology and the degree of defects of the cotton fibers.Conclusion The experimental results indicate that the tensile morphology changes of long-staple cotton fiber mainly presented as longitudinal microfibril splitting and propagation in the fiber,and the fracture mode included direct fracture,axial tear,torsional fracture and interfilament slip.The research results will helpful for reducing fiber damage during mechanical processing.
single long-staple cotton fibermechanical propertyfracture mechanismfracture morphologyXinjiang cotton
万方数据
维普
