Sealants with low viscosity based on polysulfide rubber obtained through thiol-disulfide metathesis

Abstract

In this study, a mercaptan-disulfide exchange mechanism was used to modify liquid polysulfide rubber through the reaction between JLY155 and 1,6-hexanedithiol to reduce the viscosity of the liquid polysulfide. The results indicated a decrease in the viscosity and molecular weight of JLY155 and a notable improvement in the peeling strength of the prepared polysulfide sealant, demonstrating an approach to facilitating sealant preparation without sacrificing mechanical performance. Compared to JLY155, the modified liquid polysulfide rubber exhibited a reduction in viscosity, and the reduction extent could be modulated by adjusting the ratio of JLY155 and 1,6-hexanedithiol. The mechanical properties of the prepared polysulfide sealant demonstrated optimal results at a molar ratio of 4:1 between the reactants and Tris(dimethylaminomethyl)phenol (DMP30) catalyst at a loading of 0.05 wt%. The tensile strength of the prepared polysulfide sealant reached 2.38 MPa with an elongation at break of 119.68%, and the sealant exhibited excellent peel performance, undergoing substrate failure rather than adhesion failure. This was associated with a slightly lowered storage modulus (E’) in dynamic mechanical analysis. However, increasing the amount of DMP30 catalyst increased the efficiency of the thiol-disulfide bond exchange reaction and accelerated the sealant’s curing process in later stages, consequently reducing the elongation at break.