Morphology, mechanical, bound rubber, swelling, and dynamic mechanical studies of chlorobutyl elastomer nanocomposites: effect of multiwalled carbon nanotube and solvent

Abstract

Multiwalled carbon nanotube (MWCNT) reinforced chlorobutyl elastomer nanocomposites were prepared. The morphology of nanocomposite samples has been studied from scanning electron microscopy (SEM). The effect of MWCNT loadings on mechanical properties shows increase in tensile strength, hardness, and modulus and decrease in elongation at break with MWCNT loadings, which can be attributed toward better chlorobutyl-MWCNT interaction. At higher filler loading, the rate of increase slowly decreases. The above explanation was also verified from bound rubber (BdR) measurements, showing increase in BdR contents with MWCNT loading. Swelling of the nanocomposites in chloroform, benzene, and trichloroethylene was measured and found to be dependent on both MWCNT concentration and the type of solvent used. The degree of swelling, diffusion coefficient, and penetration rate was calculated. The effect of solvent on swelling properties at different periods of time shows that the degree of swelling increases with time and decreases with concentration of MWCNT loading. Dynamic mechanical properties of nanocomposites have been studied as a function of temperature (from -100°C to 100°C) at a constant frequency of 1 Hz and 1% strain. The effect of MWCNT loading on storage modulus, loss modulus, and loss tangent has been studied. The nonlinearity in tan δ and storage modulus and loss modulus was explained on the basis of MWCNT-elastomer interaction. The smooth Cole-Cole plots explain the nonlinearity in the nanocomposites as well as good distribution of MWCNT in the elastomer matrix.

Effects of graphene oxide concentration and frequency on morphology, mechanical and rheological studies of fluoroelastomer nanocomposites

“…With increasing the concentration of nanofiller, more crosslinks and reinforcement formed during vulcanization, thus tricking the free ends of polymer chains occur; hence elongation at break decreases. 28 As the crosslinking of fluoroelastomer/GO nanocomposite increases, the hardness gradually raises may be due to increase in crosslinking density…”

“…The said observation is marked up-to 4 wt% concentration and above which loss tangent value increases, this may be due to nanofiller-nanofiller interactions which cause lossier. 28,29 Figure 4 shows that the loss factor value of FKM/GO nanocomposite increases with temperature but decreases with frequency in rubbery region, indicating that elastic responses are more enhanced than their viscous counterparts. And the magnitude of peak shift is very marginal can be attributed to the sluggish nature of the fluoroelastomer relaxation dynamics.

Figure 3.Loss factor spectra of fluoroelastomer nanocomposites as a function of temperature with different GO concentration.

Figure 4.Loss factor spectra of fluoroelastomer nanocomposites as a function of temperature at different frequency for 4 wt% GO concentration.

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“…For reinforcing nature of nanofiller, several new factors are responsible and the most important being the adhesion of the matrix to the nanofiller surface, which plays a crucial role. 28,29 At low temperature the elastomer is in glassy state with high storage modulus, with increasing temperature the elastic modulus abruptly decreases down by several orders of magnitude corresponding to the glass-rubber transition. The relaxation process is of course related to an energy dissipation associated with the glass transition phenomenon of the rubber phase.

Figure 5.Storage modulus plots of fluoroelastomer nanocomposites as a function of temperature with different GO concentration.

Figure 6.Storage modulus plots of fluoroelastomer nanocomposites as a function of temperature at different frequency for 4 wt% GO concentration.

…”

“…The said observation is marked up-to 4 wt% concentration and above which loss tangent value increases, this may be due to nanofiller-nanofiller interactions which cause lossier. 28,29 Figure 4 shows that the loss factor value of FKM/GO nanocomposite increases with temperature but decreases with frequency in rubbery region, indicating that elastic responses are more enhanced than their viscous counterparts. And the magnitude of peak shift is very marginal can be attributed to the sluggish nature of the fluoroelastomer relaxation dynamics.…”

“…For reinforcing nature of nanofiller, several new factors are responsible and the most important being the adhesion of the matrix to the nanofiller surface, which plays a crucial role. 28,29 At low temperature the elastomer is in glassy state with high storage modulus, with increasing temperature the elastic modulus abruptly decreases down by several orders of magnitude corresponding to the glass-rubber transition. The relaxation process is of course related to an energy dissipation associated with the glass transition phenomenon of the rubber phase.…”