Efficacy of Novel Nanoclay in Autohesive Tack of Brominated Isobutylene-co-p-Methylstyrene (BIMS) Rubber

Abstract

Autohesive tack is the ability of two unvulcanized rubber surfaces to resist separation after they are brought into contact for a short period under light pressure. In this work, the effect of unmodified montmorillonite (MMT) nanoclay on autohesive tack of brominated isobutylene-co-p-methylstyrene (BIMS) rubber was investigated by a 180 • peel test. The nanocomposites were characterized using X-ray diffraction (XRD) and atomic force microscopy (AFM). The autohesive tack strength dramatically increased with nanoclay concentration up to 8 phr, beyond which it reached apparently a plateau at 16 phr of nanoclay concentration. The tack strength of 16 phr of nanoclay loaded sample was nearly 158% higher than the tack strength of neat BIMS rubber. Various tack governing factors such as green strength, creep compliance, entanglement molecular weight, relaxation time, self-diffusion coefficient, and monomer friction coefficient were analyzed. The addition of nanoclay reduced the extent of molecular diffusion at the tack junction by reducing the chain mobility; however, the diffusion was still sufficient to achieve bond formation. Furthermore, the less diffused chains of the nanocomposite samples showed greater bond breaking resistance due to an increase in cohesive strength, onset of transition zone relaxation time, and monomer friction coefficient value of the BIMS matrix owing to the nanoclay reinforcement. On the other hand, the more diffused chains of the unfilled sample exhibited facile chain separation due to the poor cohesive strength of the BIMS matrix.

Synthesis and Characterization of Phenol Furfural Resin from Moringa Oleifera Gum and Biophenol and Its Application in Styrene Butadiene Rubber

“…Increase in glass transition temperature can be the reason for higher viscosity and storage modulus of the synthesized resin–rubber mixture. T g of the commercially available PF tackifier resin is also around 35 °C, comparable to the T g of the synthesized resin and the result also shows the same trend. With the increase of frequency, the loss factor decreased because of the hardening of the material at a high frequency.…”

“…Kumar et al also reported the glass transition temperature of octylphenol–formaldehyde thermoplastic phenolic resin tackifier grade: SP1068 (supplied by Schenectady International Inc, NY, USA) as 35 °C ( M w = 2100 g/mol). Hence, the glass transition temperature of the synthesized uncured resin is comparable with the reported commercial tackifying resin …”

“…As reduction of tensile modulus is the evidence of better flow, the results point out that the synthesized resin–rubber mixtures have better flowability compared to the control sample, ensuring better contact between the bonding surfaces as well as enhanced molecular diffusion. However, it should also be noted that very high segmental movement can also result in bond separation . The tensile modulus of the synthesized resin–rubber mixtures are neither too low as in the case of the commercial PF resin nor too high as in the case of modified PF resins available commercially, showing an optimum combination of strength and tackiness in them.…”

“…Application of the resin depends on its glass transition temperature, which is a function of the amorphous content of the material. Lower T g resins provide better tackifying properties compared to higher T g material and hence the present gum is expected to act as an excellent tackifier.…”

“…Hence, the glass transition temperature of the synthesized uncured resin is comparable with the reported commercial tackifying resin. 51 3.11. Effect of Synthesized and Commercial Resins on Tack Strength of the SBR−Resin Mixture.…”