Synthesis And Study Of Hydrolysis Resitance Of Thermoplastic Polyurethane

Thermoplastic polyurethane material has excellent mechanical and physicochemical properties.And with the flexible changes of formulation,the performance of thermoplastic polyurethane can be adjusted in a wide range,and it can meet the practical application needs of all walks of life.However,in some industries,due to its weak performance such as resistance to hydrolysis,its application is limited and performs poor.In some industries,such as,medical and health care,wire and cable,etc.materials are required to be covered by water for a long time.Poor hydrolysis resistance of thermoplastic polyurethane materials leads to a severe performance degradation.Equipment needs be frequent replaced,causing serious waste.Based on liquefied 4,4'-diphenylmethane diisocyanate(L-MDI),polyether glycol(PTMG1000),1,4-butanediol(BDO)and difunctional castor oil as the main raw materials,a series of TPU materials were synthesized by prepolymer method,which meets actual requirement and has hydrolysis resistant,high strength,high elongation.The TPU materials were tested by the relevant test equipment and instruments.The effects of raw materials(polyols,chain extenders),synthesis parameters(R value,hard segment content)and modified additives(difunctional castor oil,barium sulfate)were studied.The following conclusions could be made:(1)Screened and determined the type of raw materials,dosage and the synthesis parameters,and synthesized a series of TPU resins.The results show that,when using raw materials of L-MDI,PTMG1000,BDO,with the content of NCO was 10%and the R value was 1,the hardness of TPU was 85 A,the tensile strength was 24.3MPa,the elongation at break was 445%,The water absorption was 2.27%,the contact angle was 94.2°,the initial thermal decomposition temperature was 253 ?,the retention of tensile strength after deionized water soaking for 7 days at 80? was 87.17%,comprehensive performance was best,the proportion can meet the requirement of high strength,high hydrophobicity,high hydrolysis resistance.(2)Use difunctional castor oil and barium sulfate to modify the TPU resin and synthesis a series of modified TPU materials.The difunctional castor oil material introduces a large amount of hydrophobic aliphatic chains while not forming a chemical crosslinking network affecting the processability of the material.The effect of barium sulfate modification is slightly worse than that of castor oil.When the difunctional castor oil added amount is 40%of the mass of the mixed polyol,the tensile strength of TPU was 16.6MPa,the elongation at break was 505%,The water absorption is 1.56%,the contact angle is 99.5°,the retention of tensile strength after deionized water soaked for 7 days at 80 ? is 94.18%,reduced water absorption by 31.23%,increased contact angle by 5.55%,and increased tensile strength retention by 8.04%.The purpose of improving the surface hydrophobicity and hydrolysis resistance of TPU materials is achieved.The effect of barium sulfate modification is slightly worse than that of castor oil.