Interactive effects between carbon allotrope fillers on the mechanical reinforcement of polyisoprene based nanocomposites

Abstract

Abstract. Interactive effects of carbon allotropes on the mechanical reinforcement of polymer nanocomposites were investigated. Carbon nanotubes (CNT) and nano-graphite with high shape anisotropy (nanoG) were melt blended with poly(1,4-cis-isoprene), as the only fillers or in combination with carbon black (CB), measuring the shear modulus at low strain amplitudes for peroxide crosslinked composites. The nanofiller was found to increase the low amplitude storage modulus of the matrix, with or without CB, by a factor depending on nanofiller type and content. This factor, fingerprint of the nanofiller, was higher for CNT than for nanoG. The filler-polymer interfacial area was able to correlate modulus data of composites with CNT, CB and with the hybrid filler system, leading to the construction of a common master curve.

Master curves for the sulphur assisted crosslinking reaction of natural rubber in the presence of nano- and nano-structured sp2 carbon allotropes

“…The number of stacked layers appears to increase also for CNT, from the pristine allotrope to the crosslinked composite. As already commented in previous publications [25,26], a remarkable pressure is applied on the rubber sheet, during the crosslinking step. As a consequence, the rubber composite moves towards a minimum of energy and the graphitic aggregates achieve a higher degree of order.…”

“…Musto, V. Barbera, V. Cipolletti, A. Citterio, M. Galimberti reinforcement of nanosized carbon allotropes and CB has been clearly shown [25,26] and correlation has been established between the filler-polymer interfacial area and the initial modulus of composites with CNT, CB and with the hybrid filler system: a master curve was obtained, able to fit all the experimental points [25,26]. It is well known that elastomeric composites, in order to find large scale application, have to be not only reinforced but also crosslinked.…”

“…All the composites were finally homogeneized by passing them 5 times on a two roll mill operating at room temperature. Such mixing procedure has been already adopted in previous works [24][25][26] and allowed to obtain even distribution and dispersion of the carbon fillers, both nano-and nano-structured, as revealed by transmission electron microscopy. In particular, composites based on synthetic poly(isoprene) were prepared with amount 30 phr of the same CB and CNT used in the present work and with 33.3 phr of HSAG.…”

“…Two series of composites were prepared, with two contents of carbon allotropes, 4 and 35 parts per hundred rubber [phr], as the objective was to study the effect of carbon allotropes in the absence and in the presence of continuous filler network. In fact, in previous studies, it was found that the percolation threshold in poly(1,4-cis-isoprene) matrix occurred at about 7, 21 and 30 phr for CNT [24], HSAG [25,26] and CBN326 [25] respectively. Sulphur-based crosslinking reactions of all of the composites were studied through rheometric analysis.…”

“…Recently, features such as crystallinity, shape anisotropy, density, surface area and oil absorption of CNT, a nanosized graphite and CB have been comparatively investigated [23,24]. Moreover, studies on synergistic effects have been performed, both in thermoplastic [15] and elastomeric matrices [24][25][26][27]. In particular, in poly(1,4-cis-isoprene) as the polymer matrix, the synergistic effect on the mechanical…”