Natural rubber-clay nanocomposites: Mechanical and structural properties

Abstract

The mechanical properties of non-vulcanized natural rubber and dialyzed natural rubber-clay nanocomposites have been studied by uniaxial deformations to evaluate the reinforcement efficiency of the clay. We show that while non-rubber molecules contribute to auto-reinforcement, removal of these molecules improves significantly the performance of clay as reinforcement agent. These mechanical properties are discussed in relation to morphological aspects of the clay characterized by TEM and SANS. The nanocomposites prepared by "latex-mixing" with aqueous dispersions of clay are found to contain completely exfoliated clay lamellae in coexistence with tactoids. Improved mechanical properties of the nanocomposites can be modeled by the high aspect ratio of exfoliated clay platelets coupled with immobilized rubber matrix. Interestingly, presence of tactoids does not appear to compromise the excellent reinforcement properties of the exfoliated platelets. At high deformations, strain-induced alignment of the clay exhibits anisotropic scattering, with anisotropy increasing with clay concentration and stretching.

Natural rubber/graphene oxide composites: Effect of sheet size on mechanical properties and strain-induced crystallization behavior

“…This is well consistent with other studies concerning filler filled NR composites [11,47]. For two-dimensional nanofillers, for example, nanoclay or graphene, they tend to orient and align parallel to the stretching direction at a very low strain ratio [9,10,47,64]. During stretching, the NR chains in the glassy rubber will slip along the GO sheets and form stretching and parallel-arraying straight chain [46].…”

“…The excellent mechanical properties of the natural rubber would be attributed to strain-induced crystallization (SIC) [4][5][6]. The reinforcement effect of filler on NR is variously attributed to 'strain amplification' and 'stress transfer' through the filler network [7][8][9]. Nanofillers are of remarkable influence on the strain-induced crystallization of NR because of their strong interfacial interaction with polymer matrix [10].…”

Review on development of natural rubber/nanoclay nanocomposites

“…In a separate study [45], it was explained that a flocculent coagulated both rubber and silicate simultaneous without intercalating into galleries of clay. Further, excellent degree of exfoliation of clay was obtained through dialyzed aqueous rubber in which excess ionic species and other small non-rubber molecules were eliminated [46]. The eliminating process of ions in the aqueous rubber promotes modulus of the resultant product.…”

Effect of Coupling Agent, Methylene Diisocyanate, in the Blending of Poly(methyl methacrylate)-Modified Starch and Styrene-Butadiene Rubber

“…They found that when the shape factor of CNT was applied as approximate 22, the theoretically predicted values were closed to the experimentally measured values. Renzende et al 36 also used the Modified Guth-Gold model to predict the modulus of clay/NR nanocomposites. They found that when the f was equal to 48, the predicted results were well fitted with the experimental results.…”