Effect of the blooming of chemical curatives on the cyclic fatigue life of natural rubber filled with a silanized silica nanofiller

Abstract

When partly soluble chemical curatives are mixed with raw rubber, they migrate to the rubber surface, which can be detrimental to the rubber properties. Two rubber compounds with different amounts of curatives were prepared by mixing natural rubber with a high loading of precipitated amorphous white silica nanofiller. The silica surfaces were pretreated with bis(3-triethoxysilylpropyl)-tetrasulfide coupling agent to chemically adhere silica to the rubber. The chemical bonding between the filler and rubber was optimized via the tetrasulfane groups of bis(3-triethoxysilylpropyl)-tetrasulfide by adding accelerator and activator. The rubber compounds were cured and stored at ambient temperature for up to 65 days. One compound showed extensive blooming as a function of storage time. The cyclic fatigue life of the rubber vulcanizates was subsequently measured at a constant strain amplitude and test frequency at ambient temperature. The blooming of the chemical curatives reduced the cyclic fatigue life of the rubber vulcanizate by more than 100%. The migrated chemical curatives produced a thin layer approximately 15 lm in size beneath the rubber surface. When the rubber was stressed repeatedly in the fatigue test, cracks initiated in this layer and subsequently grew, causing the fatigue life of the vulcanizate to decrease.

Measuring effect of the blooming of chemical curatives on the rate of cyclic fatigue crack growth in natural rubber filled with a silanized silica nanofiller

“…In total, two rubber compounds were made (Table I). The procedures for measuring the right amounts of TBBS and ZnO for curing the rubber compounds were described previously 8…”

“…The procedures for measuring the right amounts of TBBS and ZnO for curing the rubber compounds were described previously. 8 Finally, when mixing ended, the rubber was recovered from the mixer and milled to a thickness of about 6 mm for further work. The compounds were kept at ambient temperature (21 6 2 C) for at least 24 h before their viscosity and cure properties were measured.…”

Effect of organoclay and silver‐substituted zeolite on the mechanical and antibacterial properties of a silicone rubber filled with 2‐hydroxypropyl‐3‐piperazinyl‐quinoline carboxylic acid methacrylate

“…The tear energy was found to decrease almost 84% when the full OC loading was incorporated in the rubber. Note that cracks grow through relatively weak aggregated regions in rubber [28].…”

“…Recall that aggregation can occur when the loading of OC in the rubber is too high [15]. Aggregates adversely affect the cyclic fatigue life of rubber vulcanizates [28] and under repeated stressing, cracks grow through the relatively weak aggregated areas in the rubber and this causes the cyclic fatigue life to deteriorate [29]. The aggregated areas and voids to initiate the crack growth have already shown morphologically in Fig.…”

An excellent ozone-resistant polymethylvinylsiloxane coating on natural rubber by thiol-ene click chemistry

“…However, the ozone resistance of NR is not good because of its unsaturated chain structure [1]. Numerous works have been conducted to improve the ozone resistance of NR by adding paraffin or antioxidant in NR matrix or by blending NR with other rubbers with good ozone-resistance [2][3][4]. The disadvantages of these methods are the deterioration of processability and mechanical properties of NR.…”