Reinforcement Mechanism of Carbon Black-Filled Rubber Nanocomposite as Revealed by Atomic Force Microscopy Nanomechanics.

Xiaobin Liang,Makiko Ito,Ken Nakajima

doi:10.3390/polym13223922

Abstract

In this study, atomic force microscopy (AFM) nanomechanics were used to visualize the nanoscale stress distribution in carbon black (CB)-reinforced isoprene rubber (IR) vulcanizates at different elongations and quantitatively evaluate their volume fractions for the first time. The stress concentrations in the protofibrous structure (stress chains) that formed around the CB filler in CB-reinforced IR vulcanizates were directly observed at the nanoscale. The relationship between the local nanoscale stress distribution and macroscopic tensile properties was revealed based on the microscopic stress distribution and microscopic spatial structure. This study can help us gain insight into the microscopic reinforcement mechanism of carbon black-containing rubber composites.

Highlights

Mixing nanoscale fillers with a polymer matrix to produce polymer nanocomposites (PNCs) is of substantial and growing importance
Nishi [14] observed that the molecular motion in the layer between carbon black (CB) and rubber was unaffected by the solvent by measuring the spin–spin relaxation T2 time using pulsed nuclear magnetic resonance (NMR), which indicates strong restriction of the molecular motion of rubber on the CB surface
We used atomic force microscopy (AFM) nanomechanics to measure the nanoscale mechanical property distribution of CB/isoprene rubber (IR) vulcanizate under uniaxial tension for the first time

Summary

Introduction

Mixing nanoscale fillers with a polymer matrix to produce polymer nanocomposites (PNCs) is of substantial and growing importance. Using low-field proton nuclear magnetic resonance (NMR), Litvinov et al [15] observed significantly different ethylene propylene diene monomer (EPDM) rubber chain mobilities in CB-filled EPDM and strong immobilization of EPDM chain fragments on the surface of CB. Valentin et al [16] studied polymer-filler interfaces by combining swelling experiments with low-field NMR They found that the interactions established between the polymer chains and the filler restrict the swelling process in the elastic chains near the filler surface and hinder the swelling process in the interface. Guth, and Vilgis et al [17,18] presented a theoretical model of hydrodynamic reinforcement based on the Einstein-Smallwood formula [19] to describe the relationship between elastic modulus and volume fraction of the filler. Based on the aforementioned descriptions, we found that the reinforcement mechanism of PNCs was complex due to the diversity of fillers and their spatial arrangement, and the microscopic reinforcing mechanism and mechanical behavior of this action remain unresolved

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Conclusion