Rheological properties of PDMS filled with CaCo₃: The effect of filler particle size and concentration

Abstract

The effects of filler particle size and concentration on the rheological properties of hydroxyl terminated polydimethylsiloxane (HO-PDMS) filled with calcium carbonate (CaCO 3 ) were investigated by an advanced rheometric expansion system (ARES). The Casson model was used to describe the relationship between shear stress and shear rate for steady-state measurement. Micron-CaCO 3 could not afford the CaCO 3 /HO-PDMS suspensions obvious shear thinning behavior and a yield stress high enough, whereas nanoCaCO 3 could provide the suspensions with remarkable shear thinning behavior and high yield stress. Incorporation of nano-CaCO 3 into HO-PDMS resulted in the transformation of HO-PDMS from a mainly viscous material to a mainly elastic material. With increasing nano-CaCO 3 content, shear thinning behavior of nano-CaCO 3 /HO-PDMS suspensions became more obvious. Remarkable yield stress was observed in nano-CaCO 3 /HO-PDMS suspensions with high filler content, and increased with increasing nanoCaCO 3 content. The degree of thixotropy was quantitatively determined using a thixotropic loop method. It was found that nano-CaCO 3 favored more the buildup of filler network structure in the suspensions than micron-CaCO 3 at the same weight fraction. Furthermore, increasing nano-CaCO 3 content accelerated the establishment of filler network structure in the nano-CaCO 3 /HO-PDMS suspensions. An overshoot phenomenon was observed in the nano-CaCO 3 /HO-PDMS suspensions at high shear rates.

Atomic Force Microscopy, thermal, viscoelastic and mechanical properties of HDPE/CaCO3 nanocomposites

“…Furthermore, it can be seen in the figure that at all range of frequencies, the modulus increased proportionally to the loading of CaCO 3 nanofillers. Similar finding were also reported by other research studies [42][43][44]. In Fig.…”

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.…”

Evaluation of bisphenol E cyanate ester for the resin-injection repair of advanced composites

“…Fumed oxides, for example, have been used to impart shear thinning properties in suspensions [38,40,47,51,52]. Because nanoparticles have greater surface area and shorter interparticle distances, there are greater and stronger interactions between particles that make it easier to form agglomerations thus causing the increase in viscosity and resulting pseudoplastic behavior [37,41,52]. The shear thinning behavior occurs because as the shear rate is increased, the weak network of particles is broken to release "entrapped" fluid [51].…”

“…The shear thinning behavior occurs because as the shear rate is increased, the weak network of particles is broken to release "entrapped" fluid [51]. The extent of these effects is not only influenced by the size of the particles, but also by their amount, distribution, and shape [37,52].…”