Preparation and properties of silane modified polyurethane resin
A series of silane modified polyurethane(SPU)resins were prepared by using polytetramethylene glycol(PTMEG-1000),diphenylmethane diisocyanate(MDI-50),bis(3-trimethoxysilylpropyl)amine(TMSPMA,brand GX-1170),and N-phenyl-3-aminopropyltrimethoxysilane(brand Y-9669)as raw materials,and dibutyltin dilaurate(DBTDL)as a catalyst for the end-capping treatment of polyurethane(PU)prepolymers.It was cured by moisture at room temperature,and the structure and properties of the cured elastomer were characterized.The research results showed that,(1)The structural characterization indicated that aminosilane was grafted onto the PU system,confirming the successful synthesis of SPU resin.(2)Through mechanical testing of the cured elastomer,it was found that SPU-40 had the highest mechanical strength.Thermogravimetric analysis of the cured SPU-40 and PU elastomers showed that the 50%weight loss temperature of SPU-40 was about 32.6℃higher than that of PU,indicating that the introduction of silane improved the thermal stability of PU.(3)As the content of Y-9669 increased,the regularity of polymer molecules gradually decreased,intermolecular entanglement intensified,and the glass transition temperature(Tg)gradually increased.(4)As the proportion of Y-9669 increased,the viscosity of SPU resin gradually increased and the Shore A hardness gradually decreased.(5)During the crosslinking and curing process of siloxane,there was still a portion of Si—OH exposed on the surface of the polymer,and complete crosslinking has not been achieved.(6)As the proportion of GX-1170 silane decreased,the water contact angle on the surface of SPU elastomer gradually decreased,gradually changing from hydrophobic to hydrophilic.(7)The amount of silane added had an impact on the water absorption rate of the final SPU elastomer,further affecting its surface drying time and curing time.(8)Due to the regularity of the amino silane in GX-1170,while the amino silane in Y-9669 did not have regularity,as the amino silane in Y-9669 increased,the irregularity further increased and the diffraction peak gradually widened.Therefore,the soft and hard segments of the SPU film had poor regularity and were difficult to crystallize.(9)As the proportion of GX-1170 silane decreased,the tensile strength of SPU elastomer showed a trend of first increasing and then decreasing,while the elongation at break gradually increased.Under optimal conditions,the mechanical strength of SPU-40 elastomer was as high as 8.67 MPa,and the elongation at break was 75.1%.(10)Under hydrothermal aging conditions,there was no significant decrease in transmittance,but its mechanical strength gradually decreased.Polyurethane modified with silane retained its excellent acid and alkali resistance,while SPU elastomer had good acid and alkali resistance.
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