Preparation And Properties Of Polysiloxane-Polyurethane Elastomers

As a promising polymeric material,polysiloxane-polyurethane copolymers have attracted much attention due to their estimated properties based on siloxane and urethane units.However,the reported polysiloxane-modified polyurethane materials synthesized through the condensation of silanol group or alkyl alcohol group with isocyanate group exhibited unsatisfied weathering resistance and underdeveloped mechanical properties,due to the chemical instability of Si-O-C bond and the loss of hard segments,which have,limited their industrial transition.To overcome these drawbacks,herein,the PDMS-PU elastomer gum was synthesized using the α,ω-hydroxypropylpolysiloxane(PDMS)and diphenylmethane diisocyanate(MDI).As substrate rubber,the PDMS-PU elastomer was mixed with filler and cross-linking agent to obtain enhanced mechanical properties..The effects of fillers,cross-linking agents,gum and other factors to elastomers were investigated.A maximum tensile strength of 8.76 MPa and a elongation at break of 342%demonstrated the millable PDMS-PU might be suitable to productive magnification.In addition,the heat resistance of PDMS-PU elastomer prepared byα,ω-hydroxypropylpolysiloxane as polyol is excellent,but its mechanical properties need to be improvedIn order to improve the mechanical properties,a polyether segment(PTMG)was introduced into the PDMS-PU frameworks,and the terminal hydroxyl group millable PDMS-PTMG-PU elastomer gum was synthesized in two steps.The influence of experimental factors such as filler,cross-linking agent and raw rubber on the mechanical properties were studied.The prepared millable elastomer has a maximum tensile strength of 16.31 MPa and a elongation at break of 394%.Finally,to further testify the potential industrial transition of polyether-reinforced PDMS-PU,the thermoplastic PDMS-PTMG-PU polymer was prepared by changing the reaction conditions,such as the f PDMS/PTMG soft segment content,PU hard segment content,chain extender type and other factors and the conditions of post-vulcanization treatment.The thermoplastic elastomer showed a maximum tensile strength of 38.23 MPa and a elongation at break of 694%.In summary,the polyether-reinforced strategy endows the silicone modified polyurethane excellent thermodynamic performance,which lays a solid foundation for the industrial transition of polysiloxane-polyurethane materials.