Test And Evaluation Methods For The Bending Deformation Recovery Properties Of Thermotropic Shape Memory Polymer Fabrics

With the development of technologies in the textile filed,textiles are becoming multifunctional and intellectualized.As the representative of intelligent textiles,thermotropic shape memory polymer fabrics are attracting the attention of researchers,and the relevant research has been a focus in this field.At present,the detection and evaluation methods for the bending deformation recovery properties of thermotropic shape memory polymer fabrics are still at an immature stage,and the relative test methods are unitary and used in quasi-static conditions,which can not achieve the detection and evaluation comprehensively and dynamically.Based on the domestic and foreign research status,an objective test method,a theoretical prediction model and evaluation indices were proposed in this thesis.The objective test method can simulate the dynamic recovery process of the bending deformation of thermotropic shape memory polymer fabrics using multi-sensory test system.The prediction model was built to predict the bending deformation recovery properties of thermotropic shape memory polymer fabrics by analyzing the principles of shape memory.Three stages,including the initial state(glassy state),the rapidly changing state(rubbery state)and the static state(viscous flow state),were characterized in the modeling using the bending restoring force and the recovery rate of the bending deformation.Based on the analysis of the typical output curve of the theoretical prediction model,this thesis defined six evaluation indices for the bending deformation recovery properties of the three stages,including the average change rate of the bending restoring force and the average change rate of the bending recovery displacement in the glassy state,the average change rate of the bending restoring force and the average change rate of the displacement in the rubbery state,the bending restoring force and the bending recovery displacement in the viscous flow state.An objective measuring system was developed to test the bending deformation recovery properties of thermotropic shape memory polymer fabrics based on the proposed test methods,including the mechanical devices design,the hardware construction and the software design.The verification experiment was performed to evaluate the effectiveness of the objective test system and the prediction model.By comparing the predictive values with the test results of the objective test system,the theoretical prediction model was optimized,and the optimized model can effectively predict the bending deformation recovery properties of different thermotropic shape memory polymer fabrics.In order to analyze the significance of the objective evaluation indices,an experiment based on small samples was implemented in the objective test system.Ten typical samples were tested,and the results of six indices were analyzed.The objective test results indicated that the defined evaluation indices were significant for the bending deformation recovery properties of the thermotropic shape memory polymer fabrics.In order to further verify the significance of the evaluation indices,this thesis analyzed the correlations between the objective evaluation indices(maximum bending restoring force,maximum bending displacement)and an index(bending rigidity)of KES system,and the results indicated that there was correlation between them.This thesis proposed a comprehensive evaluation and dynamic test method for the bending deformation recovery properties of thermotropic shape memory polymer fabrics,which provides a new detection and evaluation method for the development of related products.