Accelerated Aging Behavior And Service Life Prediction Of PTMG Polyurethane Fibers

Polyurethane fibers have good dimensional stability and can be used as an adaptive material in Z-pinch accelerator loads in addition to the common textile industry.In the application process of these fields,the fiber is affected by different environmental conditions such as light,heat,oxygen,and water,the microstructure changes,the performance of each fiber gradually declines,and the failure of the material leads to potential safety hazards during its use.Therefore,it is important to develop fiber aging behavior and service life prediction studies under different environmental conditions for the preparation of fibers with strong environmental adaptability.The thesis takes PTMG polyurethane fiber as the research object,and carries out ultraviolet accelerated aging test.It is characterized by SEM,FTIR,SAXS,DMA,TGA and tensile property test,etc.,and it relates to the prediction of fiber aging behavior and service life under different environmental factors.the study.The main work of the thesis and the research results obtained are as follows:(1)The effects of aging time on fiber surface morphology,chemical structure,ordered microdomain structure and mechanical properties were systematically analyzed.The results showed that with the increase of aging time,the fiber surface morphology gradually deteriorated,the relative molecular weight gradually decreased,-CN-and-CO-were broken,and the carbonyl hydrogen bonding degree first increased and then decreased,and the fiber ordered micro area The structure size increases first and then decreases.The Tg of the fiber increases first and then decreases,and the breaking strength and elongation at break gradually decrease.(2)Analyze the environmental factors that affect the chemical structure of the fiber,ordered microdomain structure,thermal stability and 300% elastic recovery rate,including UV intensity,temperature,and humidity.(3)The effects of different aging time,UV intensity,aging temperature and aging humidity on the creep resistance of the fiber were analyzed.The fitting results of different mechanical models show that the eight-element model can well fit the creep characteristics ofthe fiber.The eight-element model analyzes the response laws of instantaneous elastic strain,viscoelastic strain,and viscous strain,and discusses the equivalent applicability of time-aging time,time-UV intensity equivalent,time-temperature equivalent,and time-aged humidity equivalent.(4)Based on the UV accelerated aging experimental data,the Arrhenius equation extrapolation method,time-temperature equivalence principle,and binary statistical analysis method were used to predict the service life of the fiber.From the safety point of view,the most unfavorable principle was adopted to determine the fiber safety.Service life.Polyurethane fibers are relatively sensitive to humidity.During actual use,it should be ensured that the fibers are used at lower humidity,and the failure caused by aging effects and even safety accidents can be reduced.