Study On The Effect Of Chlorine Degradation On Properties Of Polyether Polyurethane Fibers

This study takes polyether polyurethane fiber as the research object,conducts chlorine degradation experiments under different environmental conditions,and then conducts structure and properties tests to comprehensively explore the chlorine degradation behavior of polyurethane fibers,so as to provide theoretical basis for the preparation of chlorine-resistant polyurethane fibers.The main research contents are as follows:(1)Systematic analyze the influence of environmental factors on the tensile properties,thermal properties and structure of polyurethane fibers during the chlorine degradation.The results show that:with the increase of degradation temperature and the concentration of available chlorine and the decrease of the pH value of chlorine water,hydrogen bonding in the hard segment becomes worse,the crystallinity of the hard segment decreases,and the microphase mixing increases,the glass transition temperature,peak crystalline melting temperature and crystalline enthalpy of melting of the soft segment become larger,the activation energy of the fiber decreases,and the thermal stability get worse.The breaking strength,elongation at break,300%elastic recovery rate and internal friction value of the fiber reduced,and the stress softening effect increased.(2)The effect of chlorine degradation on the dynamic viscoelasticity and creep properties of polyurethane fibers is analyzed.The results show that:as the aging time of chlorine water,effective chlorine concentration,aging temperature increases,and the pH value of chlorine water decreases,the creep strain and the residual unrecovered strain are greater,the creep recovery rate and the creep resistance are worse,the loss modulus and storage modulus of the polyurethane fiber are lower,and the peak temperature of the loss modulus moves to the high temperature direction.Chlorine degradation will reduce the elasticity and viscosity of the polyurethane fiber.At the same time,as the aging becomes more serious,the role of the elastic part of the polyurethane fiber is smaller,and the role of the viscous part is greater.(3)The effect of chlorine degradation on the dynamic viscoelasticity of polyurethane fibers in a wide frequency range is studied.The main curves of storage modulus E' and loss modulus E" of polyurethane fibers are superimposed by using the principle of time-temperature equivalence.According to the main curve,the dynamic viscoelasticity of the polyurethane fiber at different frequencies is predicted.The results show that with the increase of the test frequency,the storage modulus of the fiber after aging treatment with chlorine water at different times is larger,the loss modulus is smaller,and the temperature spectrum has the trend to the right.With the increase of the aging time of chlorine water,the magnitude of the frequency spanned by the polyurethane fiber main curve gradually increases,and at the same frequency,the storage modulus and loss modulus decrease with the increase of the aging time.The molecular weight distribution broadens with increasing aging time.With the increase of the aging time,the number of segment movement units with the same relaxation time is smaller,which makes the long-term chlorine water aging polyurethane fiber less sensitive to frequency.(4)The study found that the pH value of the three environmental factors during chlorine aging has the greatest impact on the structure and performance of polyurethane fibers.When polyurethane fibers are exposed to chlorine water,they should avoid being in a low pH environment to reduce the aging effect of polyurethane fibers to avoid failures and safety accidents.