Study On Synthesis,Processing And Properties Of Mpur Based On PCL

Millable polyurethane（MPUR）is a kind of polyurethane elastomer that can be processed by traditional rubber equipment.It has excellent mechanical properties,oil resistance,damping performance and wear resistance,and is often used in mining machinery,military industry and automobile industry.In recent years,due to the single type of raw materials,the development of millable polyurethane shows some signs of slowing down.Polycaprolactone is a new type of diol developed in modern times.Polyurethane synthesized from polycaprolactone has the characteristics of high mechanical strength and good hydrolysis resistance,and has been widely used in other kinds of polyurethane elastomers.The research on the synthesis of millable polyurethane with polycaprolactone has not been reported,so this paper has important practical and scientific significance.In this paper,polycaprolactone was used to synthesize millable polyurethane.Firstly,the effects of isocyanate type,hard segment content and molecular weight of polycaprolactone on millable polyurethane were discussed.In view of the crystallization phenomenon of raw rubber in polycaprolactone 2000 system,the crystallization phenomenon in raw rubber was reduced by using a small amount of diol in the stage of copolymerization synthesis of raw rubber,and the influence of diol on millable polyurethane was discussed.Finally,the self-synthesized millable polyurethane raw rubber was processed and discussed from four aspects:vulcanization system,reinforcement system,plasticization system and anti-aging system.Research found:（1）It is found that PPDI and TDI-80 need more chain extenders in the synthesis of MPUR with the same hard segment content,and the chain extenders contain unsaturated double bonds,which will lead to more chemical crosslinking during vulcanization.The MPUR synthesized by PPDI and TDI-80 has the advantages of high strength and good low-temperature performance of raw rubber,but its resilience and thermal-oxidative aging resistance are poor,among which the loss tangent of MPUR synthesized by TDI-80 is the largest and that of PPDI is the smallest.The MPUR synthesized by MDI and modified MDI has similar performance characteristics,and the comprehensive performance of MPUR is excellent.（2）MPUR with different hard segment content was synthesized in PCL1000/modified MDI system and PCL2000/modified MDI system.It was found that with the hard segment content increasing from 25%to 35%,the mechanical strength,hardness,heat and oxygen aging resistance and wear resistance of MPUR increased,while the resilience,elongation at break and Tg of raw rubber decreased.Under the same hard segment content,MPUR synthesized by PCL2000 has better mechanical strength and resilience,and the loss tangent tanδand Tg of raw rubber are low,but obvious crystallization phenomenon appears in raw rubber,which affects the processing of MPUR.（3）Using different kinds of diols to copolymerize with PCL2000,it was found that when 30 phr of XCP2000 and PCL1000 were added,the crystals in raw rubber disappeared.When the number of PCDL2000 is less than 15,the mechanical strength of MPUR will be improved,and the addition of PCDL2000 will not affect the thermal and oxidative aging resistance of MPUR.The addition of PTMG1000 can significantly reduce the Tg of raw rubber,and has obvious influence on the mechanical properties and thermal oxidative aging resistance of MPUR.The addition of four kinds of diols reduces the loss tangent tanδof MPUR.（4）In the vulcanization system,1.5 phr of sulfur can satisfy the crosslinking use of MPUR;if the content of DCP exceeds 3 phr,the mechanical properties of MPUR will be reduced.The reinforcing effect of N330 carbon black is good.With the increase of carbon black content,the mechanical strength of MPUR increases,and the amount of carbon black should not exceed 35 parts.The reinforcing effect of silica is not as good as that of carbon black,but MPUR reinforced with silica has better wear resistance.When 20 phr Ca CO₃is used to fill MPUR,it will not change the mechanical properties of MPUR,but it will decrease if more than 20 phr Ca CO₃is used.In the plasticizing system,the cold resistance of MPUR is better when TP95 is added,and DOP has the least influence on the mechanical properties of MPUR at the same amount.Antioxidants 4010NA and 4020have a good protective effect on thermal oxidative aging of MPUR,while AW and RD have a weak protective effect on thermal oxidative aging of MPUR.