# Thermal and Mechanical Properties of Silica-Reinforced SBR/NR/NBR Rubber Composites for Boot Tread Production

## TL;DR

This paper studies how adding NBR to SBR/NR rubber blends affects their thermal and mechanical properties for making durable boot treads.

## Contribution

The study introduces a new rubber composite formulation with improved filler dispersion and mechanical performance for footwear applications.

## Key findings

- Incorporating NBR improves filler dispersion and cross-link density in the rubber composites.
- The composites show enhanced mechanical properties like hardness and tensile strength.
- Thermal stability and curing behavior are positively influenced by NBR addition.

## Abstract

This study investigated the influence of acrylonitrile-butadiene rubber (NBR) at 5 and 15 phr on the properties of silica-filled styrene-butadiene /polyisoprene (SBR/NR) rubber blends intended for boot tread production. Fourier Transform Infrared Spectroscopy evaluated the performance of the resulting SBR/NR/NBR composites with Attenuated Total Reflectance (FTIR-ATR), which confirmed interactions between the rubber matrix and the silica filler. In addition, changes in thermal and mechanical properties, as well as cross-linking parameters, were systematically examined. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) are used to provide a comprehensive understanding of the structural, thermal, and mechanical behavior of silica-reinforced SBR/NR/NBR composites. The rheological characteristics of the tested composites were examined as a function of the mixture ratio. Atomic force microscopy (AFM) revealed variations in the sample’s surface roughness and morphology with varying rubber blend ratios. The findings confirmed that incorporating NBR improves filler dispersion, increases cross-link density, and enhances mechanical properties, including hardness and tensile strength, while also influencing thermal stability and curing behavior. The results suggest the potential of these composites for reliable, efficient sole manufacturing in the footwear industry, where durability, strength, and processability are critical requirements.