Electrical and Mechanical Properties of Fractal Graphene-Based Highly Filled Vinyl Ester Composites
Abstract
The increasing global concerns over climate change and environmental degradation have intensified the search for sustainable and efficient energy solutions. Among various alternatives to traditional fossil fuel-based power systems, proton exchange membrane fuel cells (PEMFCs) have gained significant attention due to their high efficiency, low emissions, and ability to generate clean energy. However, one of the critical challenges in fuel cell technology is the development of cost-effective, durable, and highly conductive bipolar plates (BPs), which play a vital role in the overall performance and longevity of PEMFCs.
This research aims at developing highly filled fractal graphene-based vinyl ester polymer composites suitable for applications such as bipolar plates in proton exchange membrane fuel cells. There is a growing interest in finding an alternative to the internal combustion engine because of the rising impacts of Green House Gases on climate change. Fuel cells are a clean, safe, and efficient power source that transforms chemical energy stored in hydrogen and oxygen directly into electrical energy.
The novel material investigated in this work is fractal graphene, an ultra-high purity turbostratic form of graphene. The graphene used in this work is produced in a novel, one-step, highly efficient, gas-phase and environmentally friendly process, which yields pristine graphene nanosheets. The study reviewed various methods to formulate different kinds of thermoset resin/filler systems. These approaches were further investigated at high carbon filler concentration to develop polymer composites suitable for BPs. The polymer composites were developed by compression molding of vinyl ester as a binder and conductive fillers natural graphite, synthetic graphite, carbon black, and fractal graphene. The study investigates the effects of various formulations of these carbon fillers on the electrical and mechanical properties of vinyl ester polymer composites.
The addition of fractal graphene from 0 wt.%, to 0.09 wt.% while maintaining 50 wt.% total carbon, predominantly natural graphite, significantly enhances both through-plane and in-plane conductivity compared to other formulations of the named carbon fillers. A highly filled system containing 70 wt.% carbon fillers was also investigated. The addition of 0.6 wt.% fractal graphene alone led to an 82% increase in in-plane electrical conductivity and a 133% improvement in through-plane electrical conductivity, compared to the formulation without graphene. In addition to exhibiting excellent electrical properties, these highly filled composites possessed impressive flexural modulus, strength, and tensile strength.