Tailored Interfaces in Fiber-Reinforced Elastomers: A Surface Treatment Study on Optimized Load Coupling via the Modified Fiber Bundle Debond Technique

Julia Beter,Boris Maroh,Inge Mühlbacher,Gerald Pinter,Sandra Schlögl,Thomas Griesser,Peter Filipp Fuchs,Bernd Schrittesser

doi:10.3390/polym13010036

Abstract

The interface between the reinforcement and surrounding matrix in a fibrous composite is decisive and critical for maintaining component performance, durability, and mechanical structure properties for load coupling assessment, especially for highly flexible composite materials. The clear trend towards tailored solutions reveals that an in-depth knowledge on surface treating methods to enhance the fiber–matrix interfacial interaction and adhesion properties for an optimized load transfer needs to be ensured. This research aims to quantify the effect of several surface treatments for glass fibers applied in endless fiber-reinforced elastomers with pronounced high deformations. Due to this, the glass fiber surface is directly modified with selected sizings, using a wet chemical treatment, and characterized according to chemical and mechanical aspects. For this purpose, the interfacial adhesion performance between fibers and the surrounding matrix material is investigated by a modified fiber pull-out device. The results clearly show that an optimized surface treatment improves the interface strength and chemical bonding significantly. The fiber pull-out test confirms that an optimized fiber–matrix interface can be enhanced up to 85% compared to standard surface modifications, which distinctly provides the basis of enhanced performances on the component level. These findings were validated by chemical analysis methods and corresponding optical damage analysis.

Highlights

Flexible composites combine reinforcing fibers with elastomeric matrix resulting in good mechanical properties and stability but still maintain a flexible structure
The fiber pull-out test confirms that an optimized fiber–matrix interface can be enhanced up to 85% compared to standard surface modifications, which distinctly provides the basis of enhanced performances on the component level
Modified glass fibers (GF) were obtained with varying surface polarity and chemical functionality, which are expected to distinctively affect the bond strength at the fiber–matrix interface

Summary

Introduction

Flexible composites combine reinforcing fibers with elastomeric matrix resulting in good mechanical properties and stability but still maintain a flexible structure. Test methods to study the fiber–matrix interface have been designed for the single fiber (micro scale), fiber bundle (meso scale) and laminate level (macro scale). To ensure sufficient performance at component level, which is known to consist of a large number of threads and includes numerous boundary conditions [19], it is important to investigate the material behavior at bundle level as a representative volume unit and to define the global structural behavior [20,21]. The essential material data obtained from these tests need to be validated [10,14]

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Conclusion