Preparation and characterization of hydrophilic and water‐swellable elastomeric nanocomposites

Abstract

Highly polar and hydrophilic polymers; ethylene‐vinyl acetate (EVA), epichlorohydrin rubber (GECO), and polyethylene oxide (PEO) reinforced with fillers (carbon black (CB) and/or Silica) were used to prepare water‐swellable rubber nanocomposites. The study showed that although the high content of the GECO delayed vulcanization of the corresponding compounds, the sample filled with desired ratio of GECO/PEO/EVA or GPE, cross‐linked with peroxide exhibited the highest swelling performance of ⁓150%. The samples exhibited good re‐usability performance in the re‐swollen test, after drying. At prolonged water swelling, the tensile strength dropped drastically for compounds with high content of the GPE, due to weak filler‐matrix interactions. On the other hand, the incorporated GPE also increased the rebound resilience (%) property which is a key requirement in green tire fabrication. For example; peroxide cured sample coded SR3 (GPE‐15 phr CB) obtained ⁓30% resilience in non‐swollen state and ⁓53.5% after 1440 min of water‐swelling, which represents a dramatic development of over ⁓78% in rebound resilience. Thus, a proper balance between the GPE content, curing agent and the reinforcements may guarantee high water‐swelling performance and mechanical properties integrity for multifunctional applications such as wound healing, structural works, water collection from oil spillages, and for the development of water‐based sensors.

Investigating the Effect of Curing Activators on the Cure Kinetics of Acrylonitrile–Butadiene Rubber Filled with Graphene Oxide and Reduced Graphene Oxides Nanocomposites

“…The Young's modulus was then computed by using initial slope at lower strain (<5%). Later, using the classical Equation (9), the E was adopted to calculate the total network density (n t ).…”

“…The reinforcement strength can be seen in the high values of R f = E c /E m for the composites. The reinforcement mechanism responsible for this significant enhancement may be the effective distribution of reinforcements and the strong filler-rubber bonding in the various compositions [9,10,12,32] measured by the low equilibrium swelling degree (Q r ) and high network densities created (refer to Table 5), especially between the highly oxygenated graphene sheets (GO and rGO) with and the main matrix.…”

“…Experts in polymer nano-science and those skilled in the art of rubber processing technology are making determinations to tailor rubber matrices to acquire at least one of the exclusive multifunctional properties of the two-dimensional graphene/derivative graphene sheets (GDS), which include excellent thermal conductivity of ~5000 W/(m K), ultimate strength of ~130 GPa, and a very high electrical conductivity of ~6000 S/cm 12 . Another reason is that, only small amount ~0.05 parts per hundred of rubber (phr) of GDS is used to achieve the same reinforcement effect obtained by concentrations ≥~5 phr of carbon blacks (CB), nanoclays (NC), and silica [1][2][3][4][5][6][7][8][9][10]. The tailoring involves synergy formation between the matrix and GDS by using processing techniques like spraying/coting of polymers with GDS [11], melt processing, solvent intercalation [1,12], and in situ polymerization [1,13] for advanced applications [1,7,14].…”

“…The ZnO forms zinc stearate, which activates the action of the accelerator system to increase the efficiency of vulcanization [23][24][25][26]. In the end, infinite crosslinks/network structures are formed as a result of the reactions among the sulfurating species and with the saturated (-C=C-) sites of the rubber matrix [9,10,32].…”

“…Rubber-GDS composites vulcanization have generated an ongoing debate, as to whether GDS delays or shortens the time for vulcanizing a virgin rubber matrix. The delay is a measure of higher values recorded for the on-set of curing time (t s1 , t s2 , or t s5 ) and the optimum curing time (t 90 and t 95 ) [1,8,[32][33][34] deduced from rheo-curves [1,9,10,33,35,36]. The changes in curing times with respect to the torque can further be computed into activation energies (kJ/mol) by using popular kinetic models like that of Kissinger [37] and Ozawa [38].…”