Mechanical properties of silicone rubber under high loadings of alumina trihydrate filler

Abstract

It is known that Young’s modulus of elastomers increase strongly due to high filler loadings, which is critical for practical applications and processing. An experimental study was performed in order to investigate the mechanical properties of silicone rubber, which was highly filled with alumina trihydrate (ATH) under uniaxial tensile tests. Different sizes of ATH particles having different surface conditions were used. The composites were prepared in a Z-blade mixer, and the particles were partly in situ modified. In preliminary investigations, the correct amount of silane for the in situ modification was determined and the effect of the mixing time on the mechanical properties of the cured rubber was studied. Long mixing times show generally a decrease in the modulus. This is explained by the increasing formation of bound rubber. A substantial dependence of the particle size and particle surface modification on the Young’s modulus was found. This effect can be simulated using a model based on a stiff particle surrounded by a soft shell, which has a higher modulus than the polymer. Smaller particles show a stronger increase of the modulus than larger ones, which is due to (1) higher volume of interphase area and (2) shorter distance between the particles increasing the modulus of the interphase.

Comparison of four commonly used high temperature vulcanized silicone rubber formulas for outdoor insulator and their regional adaptability

“…The tear strength of two kinds of silica filled silicone rubber obtained from this paper is different from that of Zhang due to the different amount, specific area, and particle size of the PPT silica and fumed silica . Generally, the elongation‐at‐break decreases with the increases of adhesion between the filler and polymer . An increase in the amount of crossline points makes the siloxane molecules harder to slip.…”

“…Therefore, each sample tested by N 2 absorption or laser particle size analyzer may have a large difference in particle size. Second, according to the relationship between specific surface areas and particle size, the density of filler that is unknown can influence the result. In addition, when the ultrasonic vibration time is not enough during laser particle size analysis, the diameter of particle size can be larger due to the agglomeration of fillers .…”

“…In addition, when the ultrasonic vibration time is not enough during laser particle size analysis, the diameter of particle size can be larger due to the agglomeration of fillers . Moreover, the introduction of surface defects (crystal fractures and fissures) that resulted from production process can increase the specific surface areas and thus increase the moisture absorption substantially . There are two peaks for alumina and ATH in Figure due to the test temperature of 200°C.…”

“…With alumina in HTVSR, a heat transfer network is formed, which can enhance the thermal conductivity of silicone rubber and reduce its surface temperature . The thermal conductivity, heat stability, mechanical properties, dielectric properties, and moisture absorption of the silicone rubber filled with different alumina were investigated . Effect of different ATH on the electrical, mechanical, and aging properties of silicone rubber was studied .…”

Interphase‐layer effect on deformation of silicone rubber filled with nanosilica particles

“…The average thickness of the interphase layers has recently been evaluated using a mixture law of the linearly thermal expansion coefficient by González‐Benito et al . and Ansorge and Papailiou . However, these evaluated thicknesses were not verified from experimental results.…”