Synthesis and Use of Hydroxyl Telechelic Polybutadienes Grafted by 2-Mercaptoethanol for Polyurethane Resins

摘要

The grafting of hydroxy telechelic polybutadienes (HTPBD)by 2-mercaptoethanol to saturate 1,2-double bonds which enabled an increase of the -OH functionality of HTPBD is presented.The functionalities of the virgin and grafted HTPBD were characterized both by ~1H-NMR after silylation of the hydroxy end grougps and the consumption of the mercatan was determined by iodine titration.The radical addition of 2-mercaptoethanol to HTPBD was nto complete, which is not acceptable for an industrial application.Hence, the excess of mercaptan was reacted to allyl alcolhol,leading to a new short telechelic diol able to be incorprated by addition of hexamethylene diisocyanate to both these diols.The thermal (glass transition, T_g,and decompositon temperatures),physical (gel time and viscosity),and mechanical (Shore hardness)properties were assessed.It was noted that the higher the hydroxyl functionality.the greater the Shore hardness, the viscosity,and the modulus but the lower the gel time observed with the use of grafted HTPBD in PU resins.Their T_g's were boservced to undergo a slight increase (of 4deg C)in the case of PU prepared fro Poly BD R45 HT in contrast to that noted from Poly BD 20 LM(20deg C),showing a lower phase segregation in that latter case.