Study On Synthesis Of Polyurethane Elastomer And Media Resistance

Polyurethane elastomers are widely used in industrial production and daily life due to their excellent properties.Compared with plastics and rubber materials,polyurethane elastomers have a wide range of adjustable properties,excellent damping performance,high strength,wear resistance.However,in certain chemical media,polyurethane elastomers will degrade,resulting in decreased performance and service life.Seriously cause environmental pollution and economic loss.Understanding the factors affecting the dielectric properties of polyurethane elastomers is of great significance for subsequent production and application.This article focuses on the synthesis of cast polyurethane elastomers,on this basis,through the selection of different variables for research.The main research directions are:selection of different synthesis processes and post-mature time;selection of different polyols as soft segments,adjustment of the molecular weight of the polyol,and combination of different polyols in different proportions;the combination ratio between different chain extenders,change the free isocyanate content,change the chain extension coefficient;and explore the factors that affect the grease resistance of polyurethane elastomers,the results are as follows:1.In terms of synthesis process:the low temperature performance of the prepolymer method is better than the polyurethane elastomer prepared by the semi-prepolymer method,but the mechanical strength is poor.In terms of water resistance,as the temperature of the water bath increases,the hydrolysis resistance of the polyurethane elastomer decreases,and the resistance of polyurethane elastomers to acidic solutions is lower than that of alkaline solutions.In brine at room temperature,it can maintain high mechanical properties for a certain period of time.Overall,the synthesis method has little effect on the dielectric properties of polyurethane elastomers.With the increase of curing time,the physical and mechanical properties of polyurethane elastomer and the resistance to media have been improved.2.In terms of soft segment:the mechanical strength of polyester polyurethane elastomer is generally higher than that of polyether polyurethane elastomer,but the low temperature performance is poor.As temperature increases,water resistance decreases,and the order of hydrolysis resistance is:PTMG2000>PCDL2000>PCL2000>218>XCP2000D,the order of medium resistance is 30g/L NaCl>10%H₂SO₄>10%Na OH>10%HCl.As the molecular weight of the polyol increases,the glass transition temperature of the polyurethane elastomer decreases,and the low temperature performance is improved.The water resistance performance is not obvious in60?water bath.In the 90°C water bath,increasing the molecular weight of the polycaprolactone polyurethane elastomer decreases the hydrolysis resistance,and the molecular weight does not significantly affect the water resistance of the PTMG system.When XCP2000D and PCL2000 are used together,as the content of PCL2000 increases,the mechanical strength,the low temperature performance and media resistance increase.The order of resistance to chemical media is:30g/L NaCl>10%H₂SO₄>10%NaOH>10%HCl.3.In the hard segment:when TMP and BDO are used together,the addition of TMP content increases the polyurethane elastomers'resistance to media but the mechanical strength decreases.Improving the temperature will increase the degree of hydrolysis.When NCO%are increased,the mechanical properties of the elastomer will be increased and the temperature properties will be decreased.The hydrolysis resistance,acid resistance and alkali resistance of polyurethane elastomer will be decreased with the reduce of NCO%.When NCO%=9%,polyurethane elastomer has the best mechanical strength and medium resistance.Increasing the chain extension coefficient can improve the physical and mechanical properties and medium resistance of polyurethane elastomers,but when f=1,the physical and mechanical properties and medium resistance are the worst.4.In terms of grease resistance:from the point of view of the strength retention rate before and after immersion,the high-temperature resistant grease performance capabilities of the three selected soft segments are:PTMG1000/330N>PTMG1000/330N>PCDL1000.PCDL1000 has the highest initial and oil-resistant mechanical strength and can be used for a long time.The thermal stability of the polyurethane elastomer when used in combination with PTMG1000 and PTMG2000 is better than that when used with 330N.When HQEE and TMP are used together,their oil resistance decreases as the TMP content increases.When the TMP content increases to a certain extent,the oil resistance improves but it is not as good as the oil resistance when HQEE is used alone.