Characterization of the Viscoelastic and Vulcanization Behavior of Natural Rubber Nanocomposites Having Different Levels of Nano Silicate/Black

Abstract

The effects of various loadings of nano layered silicate (NS) and black (BK) were investigated on the cure and stress relaxation behavior of natural rubber (NR), for both uncured and cured states. The changes in elastic (S′) and viscous (S″) vulcanization torques were meaningfully different. The drop in S″max (DS″) was larger for NS than BK; and lowered when the amounts of reinforcements increased. As the nano particles concentration increased, peak of S″ happened in shorter time and higher conversion of cure. Relaxation curves were divided into two viscous and elastic regions at short and long times. With increasing nano filler content, elastic (Ae) and viscous (Av) slopes of relaxation increased. Av was bigger than Ae for uncured compounds while after cure the reverse trend was observed. Vulcanized samples had higher Ae, which clearly confirmed different viscoelastic behavior caused by curing. Comparing with BK, NS had more significant effect on the rate of falling of the relaxation modulus, especially after curing. The ratio of drop in relaxation modulus in the viscous zone to the elastic zone (ΔGv/ΔGe) decreased as a function of NS/BK content for uncured samples; and increased with NS and BK level after cure. In both cured and uncured samples, NS was more effective on ΔGv/ΔGe than BK. An interesting correlation was found between viscoelastic parameters obtained from cure and stress relaxation studies.

Effects of two types of nanoparticles on the cure, rheological, and mechanical properties of rubber nanocomposites based on the NBR/PVC blends

“…Meanwhile, the viscous nature is related to the modulus variations over long‐term, indicating the time‐dependent strain. Various responses and interactions are fully described in the more recent works . In our work, elastic responses involve the reorientation of the polymer chains, rearrangement of entanglements, adhesion between matrix phases, and filler–matrix interactions.…”

“…Various responses and interactions are fully described in the more recent works. 30,39 In our work, elastic responses involve the reorientation of the polymer chains, rearrangement of entanglements, adhesion between matrix phases, and filler-matrix interactions. The last mentioned elastic response is accrued in the nanocomposites.…”

“…Mohammadian‐Gezaz and Karrabi reported that in natural rubber (NR) compounds filled with organoclay (OC), with raising nanoparticle content, led to a higher initial relaxation modulus. In another study, they concluded that the enhancing of OC to the NR compounds increased both the elastic and viscous slopes in the relaxation curve, which is the cured samples had a higher elastic slope and a lower viscous slope than uncured ones …”

“…In another study, they concluded that the enhancing of OC to the NR compounds increased both the elastic and viscous slopes in the relaxation curve, which is the cured samples had a higher elastic slope and a lower viscous slope than uncured ones. 30 Although some studies have been done on the curing, rheological, and mechanical properties of NBR/PVC blend, 1,17,21,31 any article has not been published on the role of nanoparticles with platelet morphology and very high surface area on the curing, rheological, and mechanical properties simultaneously so far. Due to the major application of these nanocomposites in the automotive industry, it is important to study various properties of these nanocomposites.…”

"Curing Characterization of EPDM Rubber Compounds using RPA: Effects of Cure Conditionsc"

“…It can be operated in rotation dynamic and relaxation modes. Rheological characterizations of gum and rubber compounds [8][9][10] and the cure behavior of compounds [11][12][13] can be investigated using RPA. The reciprocal cone geometry of RPA can be seen in Figure 1 schematically.…”