# Improving Adhesion of UHMWPE with Epoxy Matrix by Reactive Ion Etching of UHMWPE Using Ar–O2 Plasma and the Effects of Plasma on Adhesion at the Micro- and Macroscale

## TL;DR

This paper shows how plasma treatment improves the bonding of UHMWPE fibers with epoxy composites, enhancing their structural performance.

## Contribution

A novel method using Ar–O2 plasma reactive ion etching is introduced to significantly enhance UHMWPE-epoxy adhesion.

## Key findings

- Plasma treatment increases interfacial shear strength by up to 181% compared to untreated fibers.
- Failure mode shifts from interfacial failure to defibrillation after plasma treatment.
- Oxygen-bearing functionalities on the fiber surface improve bonding with epoxy resin.

## Abstract

Ultrahigh molecular weight polyethylene (UHMWPE) fibers
offer an
excellent range of mechanical properties, but their applications in
composites are limited due to their inert surface, which limits matrix
wetting. This study employs reactive ion etching (RIE), using Ar–O2 gases to significantly improve the adhesion of UHMWPE fibers
(with no surface finish) and tapes with epoxy at the micro- and macrolevels.
Various oxygen-bearing functionalities are observed on the surface
of the fiber after plasma treatment, confirmed by FTIR. These functional
groups improve links between the unsized fiber and Prime20 LV epoxy
resin. Consequently, the apparent interfacial shear strength (τIFSS), measured by microbond testing, increases by 143%, 171%,
and 181% as a result of plasma exposure for 10, 60, and 300 s, respectively,
compared to untreated fibers. However, the frictional stress (τf) in the postdebonded region of the microbond curve remains
constant and independent of plasma exposure. Short-beam shear testing
of interleaved composite laminates shows a 63% increase in the ILSS,
along with a change of failure mode from interfacial failure to defibrillation
of the tape itself after plasma treatment, mitigating a key limitation
of using this material in structural applications.