Enhancement of the cure behavior and mechanical properties of nanoclay reinforced NR/SBR vulcanizates based on waste tire rubber

Abstract

The most important goal of this work was to investigate the different physical and mechanical properties of the nanoclay (montmorillonite, MMT)-filled 50/50 wt.% of natural rubber/styrene butadiene rubber (NR/SBR) blend containing 40 phr of waste tire rubber (WTR) in the presence of bio-resin. The MMT was added into the NR/SBR/WTR blends and processed via a two-roll mill to prepare blends at 0, 5, 10, 15, and 20 phr of nanoclay filler and a constant concentration of 10 phr of bio-resin. The morphology, rheological, percent of swelling weight, and mechanical properties of the MMT-reinforced NR/SBR/WTR blends were examined. The cure characteristics of the blends showed that MMT significantly affected the scorch and vulcanization times, torques, and curing rate of NR/SBR/WTR blends at all filler contents. Also, the findings revealed that the MMT was an efficient reinforcing material for the NR/SBR/WTR blend, improving crosslink density, tensile and tear strengths, hardness, compression set, and abrasion resistance. The tensile strength of filled NR/SBR/WTR blends achieved its maximum value (11.2 MPa) when the MMT content was 15 phr. While the elongation percent of the filled blends decreased for all MMT concentrations compared with the pristine blend. The elastic modulus and tear strength of the blends improved as the MMT loading increased. The hardness (Shore A) continued to increase with increasing MMT loading. On the contrary, the rebound resilience gradually decreased leading to improved interaction between the matrix and filler.