Preparation And Propertites Of Mpue Based On NDI

Polyurethane foam(PUF)is a new type of polymer synthetic material.Compared with other foam materials,PUF has many advantages in performance.In addition to relatively small density,it also has odorless gas permeability,high temperature resistance,organic solvent resistance and cell structure.The traditional pure MDI system microcellular polyurethane elastomer(MPUE)has poor mechanical properties and dynamic properties compared with the NDI system,but the cost of the NDI raw material is too high.Therefore,it is studied that the microporous polyurethane elastomer with excellent preparation performance and low cost is very practical and promising.This topic combines MDI and NDI.Firstly,MPUE is prepared by prepolymer method.The influence of the structure of soft segment on MPUE performance is studied.The MPUE was synthesized by semi-prepolymer method.The effects of the type and ratio of chain extender on the properties of the material were studied.The effects of chain extension coefficient and hard segment content on the properties of the material were studied.The material synthesized in this paper is microporous structure.Therefore,the effects of blowing agents,foam stabilizers,fillers and catalysts on the performance of MPUE were investigated.Finally,the effects of synthetic process and MDI ratio on the properties of microcellular polyurethane elastomers were investigated.The study found:(1)Compared with polyether polyol,microporous polyurethane elastomer synthesized by polyester polyol has better physical and mechanical properties,better heat-resistant air aging performance,poor elasticity,high internal friction and tensile permanent deformation.The aging resistance of hot water is relatively poor.The polyether microporous polyurethane has low body consumption,low glass transitiontemperature,wide temperature range corresponding to the loss factor peak,and the low temperature performance of the microporous polyurethane of the soft section PPG220 is excellent,and is basically unchanged at-40?.The polyester polyol is used in combination,when PEA20/PEA10=80/20,the obtained microcellular polyurethane elastomer has the best physical and mechanical properties,and the loss peak shifts toward the high temperature direction as the ratio of the PEA10 is increased.The polyether polyol is used in combination,when PPG220/PPG210=90/10,the mechanical strength of the material is high.As the PPG ratio is increased,the peak loss of the material increases,and the loss peak shifts toward the high temperature.Polyester polyol and polyether polyol are used together,when PEA20 and PPG220 are used together,the mechanical strength of the material is high,and as the ratio of PPG220 is increased,the damping factor of the material decreases,and the loss peak shifts toward the low temperature.PEA20 is used in combination with different polyester polyols,when 2304 is uesd,the strength of the material is the highest and the internal consumption is low,and when the alcohol is used,the compression set of the material is the lowest.(2)Changing the type of chain extenders.The results showed that the microporous polyurethane elastomer obtained by KE chain extender had the best mechanical properties and low temperature performance,and the internal friction was low,followed by KB.The strength of the microporous polyurethane material obtained by TMP chain extender is extremely low.When the glycol chain extender is used together with TMP,the degree of cross-linking of the system is increased,the compression set is reduced,and the glass transition temperature is increased,and the internal friction is increased.The microporous polyurethane material was synthesized from the same kind of raw materials.As the hard segment content of the system increased,the hardness and static stiffness of the material increased significantly,the internal friction decreased,the compression set was reduced,and the elasticity did not change significantly.When the amount of chain extender was changed,the hardness,strength and impact rebound of the obtained microcellular polyurethane elastomer decreased with the increase of the amount of chain extender,and the elongation at break increased,the internal friction is reduced and the compression set is lowered.(3)Changing the amount of foaming agent,the results show that with the increase of the amount of foaming agent,the strength and hardness of the obtained microporous polyurethane material decrease,the elasticity of the material increases,the storagemodulus of low temperature decreases,and the internal friction increases.The cell size becomes larger and the cell is densely packed.The catalyst system used for the reaction was adjusted,and the catalyst cat-1 was used in combination with the catalyst cat-2.As the amount of cat-2 increased,the foaming reaction rate increased,the number of cells increased,and the cell uniformity deteriorated,and the strength of the material,The hardness decreases,the elasticity rises,and the low temperature storage modulus decreases.By changing the amount of foam stabilizer,the strength of the prepared microporous polyurethane material first increased and then decreased with the increase of the amount of foam stabilizer,the internal friction increased slightly,the pore diameter of the matrix became smaller,and the foam bulk density increased.When the ultraviolet absorber 5566 is added,the strength of the material is lowered,the yellowing resistance is improved,the cell size in the matrix is reduced,and the cell pore size distribution is uneven.(4)The microporous polyurethane elastomer is synthesized by different methods.Compared with the semi-prepolymer method,the material synthesized by the prepolymer method has good elasticity,the heat resistance of the material is good,and the internal consumption is low.The material obtained by the monomer mixing method has better heat resistance than the prepolymer mixing method,high strength,good elasticity,low internal consumption,and small cell pore diameter.The combination of MDI and NDI is used to change the ratio of the two isocyanates in the material.The results show that with the increase of the ratio of MDI,the strength and modulus of the material decrease,and the heat resistance also decreases.Under the action of external dynamic frequency,The internal friction of the material increases and the cell size in the matrix increases.