The Role of CNTs in Promoting Hybrid Filler Networking and Synergism with Carbon Black in the Mechanical Behavior of Filled Polyisoprene

Abstract

The filler networking process promoted by multiwalled CNTs is studied in neat and CB-filled poly(1,4-cis-isoprene) matrices. TEM analysis, tensile, dynamic-mechanical, and electrical measurements reveal that the CNTs form a filler network at low concentration in neat PI and a continuous hybrid filler network at a lower CNT concentration in the presence of CB, with a remarkable increase of the nonlinear dynamicmechanical behavior of the nanocomposites at low deformation. A synergistic effect between CB and CNTs is demonstrated. The addition of CNTs to the CB-filled PI matrix leads to initial modulus values much larger than those calculated by simple addition of the two initial moduli of the composites containing only CB and only CNTs, respectively

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

“…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.…”

“…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.…”

“…Carbon black and carbon nanofillers have been separately investigated for quite a long time. 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].…”

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

“…In natural rubber as the polymer matrix (with epoxidized natural rubber as the compatibilizer), improvements of mechanical, thermal and dynamic-mechanical properties were observed [18] when the nanographite was added to CB (N234). Previous research of the authors on PNC with hybrid carbon fillers in a poly(1,4-cis-isoprene) (PI) matrix revealed a dramatic enhancement of the material initial modulus, when a small content of nanofiller was added to a composite containing a prevailing amount of CB (N326, 60 php) [19,20], and also a remarkable reduction of the modulus with the increase of the strain amplitude. In the case of CNT as the nanofiller [19], transmission electron microscopy (TEM) analysis documented the formation of hybrid CNT-CB networks at very low CNT content (about 2 php).…”

“…Previous research of the authors on PNC with hybrid carbon fillers in a poly(1,4-cis-isoprene) (PI) matrix revealed a dramatic enhancement of the material initial modulus, when a small content of nanofiller was added to a composite containing a prevailing amount of CB (N326, 60 php) [19,20], and also a remarkable reduction of the modulus with the increase of the strain amplitude. In the case of CNT as the nanofiller [19], transmission electron microscopy (TEM) analysis documented the formation of hybrid CNT-CB networks at very low CNT content (about 2 php). The initial modulus values of the nanocomposites containing the hybrid CNT-CB filler network were found to be much higher than those calculated through the simple addition of the initial moduli of the composites containing only CB and only CNTs, and synergism between the two fillers was thus commented [19].…”