Influence of incorporating CaCO₃ into room temperature vulcanized silicone sealant on its mechanical and dynamic rheological properties

Abstract

Silicone sealants with low modulus and high elongation were prepared by using ketoxime silane as chain extender agent, and a novel silane coupling agent acting as adhesion promoting agent was synthesized. Mechanical properties of vulcanized polydimethylsiloxane (PDMS) filled with large amounts of carbonate calcium (CaCO 3 ) and dynamic viscoelastic properties of unvulcanized samples were investigated through electronic multifunctional tensile tests, dynamic mechanical analyzers, and dynamic rheological measurements. The results of mechanical tests indicate that diminishing the particle diameter size, narrowing the particle diameter distribution, and increasing the filler amount lead to a relative high tensile strength and modulus at 100% elongation, but a relative low elongation at break. The reasons for these are believed to be the evolution of molecular interactions and the formation of additional physical crosslinking induced by the filler network. Compared to virgin PDMS, there is a significant elevation of glass transition temperature with filler addition. On the other hand, the results of dynamic rheological measurements reveal that as filler amount increases, the span of the linear viscoelastic region in which dynamic storage modulus (G 0 ) is constant in low strain amplitude narrows. However, a characteristic plateau phenomenon appears in low frequency regions together with increasing the width and height of the modulus plateau. This phenomenon is also ascribed to the formation of a filler network due to filler-polymer and filler-filler interaction.

Structure‐rheology responses of polylactide/calcium carbonate composites

“…In the filler structure models, it has been widely accepted that when the particle loading is above percolation threshold, a secondary network structure will form. [22][23][24][25][26][27][28] Because of the interactions between the particles as well as particles and polymer matrix, there is either a particle-particle or particle-matrix ''network'' formation. Therefore, the filled polymers exhibited some particular rheological properties due to the different structures.…”

A comparative study on curing characteristics and thermomechanical properties of elastomeric nanocomposites: The effects of eggshell and calcium carbonate nanofillers

“…Several researchers have already prepared polymer nanocomposites using the micron-sized and nanosized CA inorganic filler. [2][3][4][5][6][7][8][9][10][11][12] To avoid agglomeration, especially when CA nanofiller is used, the surface energy resulting from filler-filler interactions needs to be lowered via coating the filler surface with carboxylic monomers like stearic acid. 2,3,6,10 The nanosized CA has occasionally been used to prepare elastomeric nanocomposites with satisfactory thermal and mechanical properties.…”

Linear/Nonlinear Rheological Properties and Percolation Threshold of Polydimethylsiloxane Filled with Calcium Carbonate

“…In particular, the incorporation of fillers into rubbers results in remarkable changes in the viscoelastic behavior of these materials. [2][3][4] Recently, calcium carbonate (CaCO 3 ) plays an increasingly important role and has been extensively applied in rubbers, plastics, sealants and pigments industry due to its remarkable benefits such as abundant raw material resource, low price, stable properties and simple processing procedure. [5][6] It can not only reduce the manufacturing cost but also impart enhanced performances such as tensile strength, modulus, elongation at break, thixotropy and storage stability to the elastomeric materials.…”

“…10) Depending on whether inter-particle attractions or interactions between particles and polymer chains are stronger or not, there is either a particle-particle or particlematrix network formation. 3) In addition, some studies concerning the mechanism of reinforcement by filler particles have been reported recently. [11][12][13][14] As 3)…”