Effects of in‐situ functionalization of carbon nanotubes with bis(triethoxysilylpropyl) tetrasulfide (TESPT) and 3‐aminopropyltriethoxysilane (APTES) on properties of epoxidized natural rubber–carbon nanotube composites

Abstract

Composites of carbon nanotubes (CNT) and epoxidized natural rubber (ENR) were prepared by in‐situ functionalization of CNT with two alternative silane coupling agents: bis(triethoxysilylpropyl) tetrasulfide (TESPT) and 3‐aminopropyltriethoxysilane (APTES). The reactions of ENR molecules with the functional groups on CNT surfaces and with the silane molecules were characterized by Fourier transform infrared. Furthermore, cross‐link density, relaxation behaviors, curing, mechanical, electrical, and morphological properties of pristine ENR and the ENR composites were investigated. Very low percolation thresholds, at CNT concentrations as low as 1 phr, were observed in the ENR–CNT and the ENR–CNT–TESPT composites. This might be attributed to improvements in the chemical linkages between ENR molecules and functional groups on CNT surfaces that led to a homogenous dispersion of CNTs in the ENR matrix, with loose CNT agglomerates. POLYM. ENG. SCI., 55:2500–2510, 2015. © 2015 Society of Plastics Engineers

Effect of bis(triethoxysilylpropyl) tetrasulfide (TESPT) on properties of carbon nanotubes and conductive carbon black hybrid filler filled natural rubber nanocomposites

“…On the other hand, the ϴ max and φ c of the composites were significantly improved, reaching 10 μS/cm and 1 phr of CNT, when epoxidized natural rubber (ENR) was CNT filled instead of using unmodified NR. This is due to the polarity of oxirane rings in the ENR [2]. Both physical and chemical interactions occur between ENR and CNT surfaces.…”

“…In particular the absorption peak at 1126 cm -1 reveals interaction to form Si-O in the CNT/CCB-grafted TESPT and the C-C in the NR [16], with proposed reaction mechanisms shown in Figure 2. According to the polar functional groups on the CNT (~2-5% of hydroxyl and carboxylic groups [2,15,17]) and CCB surfaces [18], the condensation reactions between TESPT and CCB together with CNT surfaces possibly propagated when [16][17][18]. In addition, during curing the active sulfur atoms on CNT/CCB-grafted TESPT are capable of bonding to NR molecules through C=C bonds and with CH 2 in the allylic position (Reaction (B)) [15,16].…”

“…In Figure 1b, it is clearly seen that the ω pir at the wavenumber of 870 cm -1 of pure ENR and ENR vulcanizates significantly decreased with addition of CCB, CNT, CNT/CCB, or in particular the addition of CNT/CCB with TESPT silane coupling agent. This might be attributed to the oxirane rings in ENR that are easily broken to form diol groups during mixing at high temperature and shear [2,15]. These diol groups are capable of reacting with the polar functional groups on CCB and CNT surfaces ((Reaction (C) in Figure 2).…”

Effect of carbon nanotubes decorated with silver nanoparticles as hybrid filler on properties of natural rubber nanocomposites

“…It is noted that the aggregates of secondary fillers could connect to the CNT encapsulates and form CNT‐secondary filler‐CNT pathways in the NR composites to carry the electric current in an electric field. Also, on increasing filler volume fraction in the system, the insulating NR absorbed on the filler surfaces becomes thinner, which significantly improves conductivity . However, the optimal conductivity of a composite can also be improved by a highly conductive secondary filler, particularly by metal particles.…”

Effects of hybrid filler networks of carbon nanotubes and carbon black on fracture resistance of styrene‐butadiene rubber composites

“…Recently, because of their exceptional electrical conductivity, thermal conductivity, and reinforcing efficiency, one‐dimensional carbon nanotubes (CNTs) have been regarded as promising nanofillers in rubber industry . However, the highly entangled agglomeration of CNTs in rubber composites is still discouraging .…”