The Adhesion of Plasma Nanocoatings Controls the Shear Properties of GF/Polyester Composite.

Tomas Plichta,Milan Zvonek,Veronika Sirjovova,Gerhard Kalinka,Vladimir Cech

doi:10.3390/polym13040593

Abstract

High-performance fibre-reinforced polymer composites are important construction materials based not only on the specific properties of the reinforcing fibres and the flexible polymer matrix but also on the compatible properties of the composite interphase. First, oxygen-free (a-CSi:H) and oxygen-binding (a-CSiO:H) plasma nanocoatings of different mechanical and tribological properties were deposited on planar silicon dioxide substrates that closely mimic E-glass. The nanoscratch test was used to characterize the nanocoating adhesion expressed in terms of critical normal load and work of adhesion. Next, the same nanocoatings were deposited on E-glass fibres, which were used as reinforcements in the polyester composite to affect its interphase properties. The shear properties of the polymer composite were characterized by macro- and micromechanical tests, namely a short beam shear test to determine the short-beam strength and a single fibre push-out test to determine the interfacial shear strength. The results of the polymer composites showed a strong correlation between the short-beam strength and the interfacial shear strength, proving that both tests are sensitive to changes in fibre-matrix adhesion due to different surface modifications of glass fibres (GF). Finally, a strong correlation between the shear properties of the GF/polyester composite and the adhesion of the plasma nanocoating expressed through the work of adhesion was demonstrated. Thus, increasing the work of adhesion of plasma nanocoatings from 0.8 to 1.5 mJ·m−2 increased the short-beam strength from 23.1 to 45.2 MPa. The results confirmed that the work of adhesion is a more suitable parameter in characterising the level of nanocoating adhesion in comparison with the critical normal load.

Highlights

Controlled synthesis of functional coatings used for surface modified materials is a fundamental step in a wide range of applications
We focused on the development of plasma nanocoatings with different adhesions to planar glass, measured by a nanoscratch test, to demonstrate its effect on fibre–matrix adhesion in a glass fibre-reinforced polyester (GF/polyester) composite using a short beam shear test [27,28]
71% O2 in TVS/O2 mixture) because it has previously been shown that the nanocoatings prepared from TVS/O2 mixture improved the shear properties of a polymer composite in contrast to plasma nanocoatings prepared from pure TVS [41]

Summary

Introduction

Controlled synthesis of functional coatings used for surface modified materials is a fundamental step in a wide range of applications. Polymer composites are high-performance materials that combine a flexible polymer matrix with reinforcing components (particles or fibres) with higher strength, elastic modulus and stiffness [4]; their outstanding properties are based on the synergism of both kinds of components. These components are mostly incompatible because their chemical and mechanical properties are quite different [5,6].

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Conclusion