Effects of temperature, strain rate, and cyclic loading on mechanical behavior of silane‐modified polyurethane sealant

Abstract

To evaluate the mechanical properties of modified polyurethane sealants in engineering applications, the influences of temperature, strain rate, and cyclic loading on the mechanical properties of silane‐modified polyurethane sealant were experimentally investigated. The monotonic tensile experiments with various strain rates and temperatures were conducted, and strain rate and temperature dependent nonlinear stress–strain curves were obtained. The results showed that the silane‐modified polyurethane sealant exhibited temperature dependence at constant strain rate and rate dependence at room temperature. However, it is shown no obvious rate dependence at temperature of 150°C. In addition, the multi‐step cyclic loading experiments with mean strain decrease and increase at each step were carried out to analyze the influence of cyclic loading and cyclic loading history at different temperatures. The results demonstrated that the viscous behavior of the materials was evidently observed in the first step and disappeared in other steps for the four‐step cyclic loading with mean strain decrease case. Moreover, the cyclic stress relaxation of the materials was not obvious due to the prior cyclic loading with higher mean strain history, while the cyclic stress relaxation of the material continued to occur for the prior cyclic loading with lower mean strain history, and the cyclic strength of the materials decreased with the increase of temperature.

Experimental investigation on mechanical behavior of silane‐modified polyurethane sealant under biaxial cyclic loading

“…The physical properties of HP-172B after curing are presented in Table 1. 4 In the cruciform specimen design, it is considered that the stress concentration location of the specimen under biaxial loading condition should be in the center of the cruciform specimen. The four tensile arms of the specimen are designed to be circular arcs to reduce the stress concentration here.…”

“…The results revealed that the changes in ratcheting strain and ratcheting strain rate are proportional to the stress amplitude and the mean stress, and the loading history has a significant influence on the ratcheting strain. Zhang et al 3,4 performed experimental investigations on silane-modified polyurethane sealant and TB991 weld sealant under uniaxial cyclic loading, analyzing the effects of strain amplitude, mean strain, temperature, loading rate, and loading history on fatigue performance by investigating cyclic stress relaxation, slope variable, and dissipated energy. Tao et al [5][6][7] studied the influence of mean stress and shear stress amplitude on the fatigue life of epoxy resin through uniaxial tensile and torsional fatigue tests.…”

Synthesis of hydroxyl silane coupling agent and its application in preparation of silane‐modified polyurethane

“…The modified PU does not release CO 2 gas when it cures with moisture from the air, overcoming the inherent deficiencies of PU such as inadequate weathering performance, resulting in an outstanding performance similar to that of silicone. [9][10][11][12][13][14] Polyurethane is characterized by exceptional strength, toughness, and elasticity over a broad range of hardness, which can be achieved by varying the ratio of hard and soft segments. The NCO:OH ratio can be adjusted to alter this ratio, resulting in changes in molecular weight, glass transition temperature, thermal stability, hardness, and tensile strength among other properties.…”

“…The modified PU does not release CO 2 gas when it cures with moisture from the air, overcoming the inherent deficiencies of PU such as inadequate weathering performance, resulting in an outstanding performance similar to that of silicone. [ 9–14 ]…”

Study on characterization methods of the deformation properties of soft material polydimethylsiloxane using the indentation test

“…Mechanical property is one of the integral indicators for soft materials' application. Characteristic parameters such as Young's modulus, tensile strength and breaking elongation can be used to characterize the mechanical properties of soft materials [16][17][18][19]. Compared with metal materials and other polymer materials, large deformation under small load is a typical characteristic of soft materials.…”