ENHANCEMENT OF WETTING AND MECHANICAL PROPERTIES OF UHMWPE BASED COMPOSITES THROUGH ALUMINA ATOMIC LAYER DEPOSITION

Ultrahigh molecular weight polyethylene (UHMWPE) fibers suffer from poor adhesion to polar matrices in composites due to their chemically inert surface. This drawback has limited the use of UHMWPE-based fabrics and composites. Atomic layer deposition (ALD) is a useful method of constructing a thin oxide layer with a variety of oxides available, enabling a non-destructive method for surface modification. In this work, UHMWPE fibers and fabrics were coated with alumina (Al₂O₃) layer, using two precursors, Trimethylaluminum (TMA) and water, to a final coating thickness of 30 nm. Laminates were prepared from the treated fabrics for mechanical properties evaluation. The wettability of the alumina-coated fibers was studied in situ with an environmental scanning electron microscope (ESEM). The contact angle was reduced by 44–49%, i.e. the wettability was increased. Flexural tests showed major improvements in the flexural modulus, flexural strength, interlaminar shear strength (ILSS), resilience, and toughness. Frequency dependence tests by dynamic mechanical analysis (DMA) showed an improvement in storage modulus at all tested frequencies, insinuating on higher impact toughness at both low and high strain rates. Failure analysis revealed a change in the failure mode, from adhesion failure and pinholes formation to cohesion failure and mixed failure modes. The use of alumina-coated UHMWPE in composites shows high technological potential and may open new markets and applications, where UHMWPE could not be considered before.