Design and verification of evaluation method for storage stability of sealant

Abstract

ABSTRACT The components of the sealant are diverse and complex, and there are differences in the relative molecular weight and solubility parameters of each component, which is a thermo-dynamic unstable system. Under long-term static storage and service conditions, the joint sealant is prone to automatic condensation and segregation, which degrades its road performance. At present, little attention is paid to the storage stability of the joint sealants. The current specifications have no clear requirements for this performance, which limits the service life of the joint sealant to a certain extent. This paper investigates the influence of sealant segregation on its macroscopic properties, microstructure and components was investigated, and reveals the reasons for the segregation behavior of the sealant. At the same time, based on the shortcomings of the existing evaluation methods for storage stability and in combination with the segregation behavior of the sealant, the viscosity difference is proposed as a supplementary evaluation index for storage stability, the viscosity difference at 180 °C with a recommended threshold of 2 Pa·s, together with a softening point difference threshold of 5 °C. The segregation test conditions are optimized to a tube diameter of 50 mm, temperature of 185 °C, and duration of 8 h.