# Ink-Based Additive Manufacturing of a Polymer/Coal Composite: A Non-Traditional Reinforcement

## TL;DR

This study explores using coal as a reinforcement in 3D printing to improve material properties and promote sustainable coal use.

## Contribution

The novel use of coal as a reinforcement in direct ink writing 3D printing is introduced, enhancing mechanical properties.

## Key findings

- A 2 wt% coal concentration improves tensile and flexural properties by 35% and 12.5%, respectively.
- Coal can be used to 3D print various geometries, suggesting new sustainable applications for coal.

## Abstract

Coal, a crucial natural resource traditionally employed
for generating
carbon-rich materials and powering global industries, has faced escalating
scrutiny due to its adverse environmental impacts outweighing its
utility in the contemporary world. In response to the worldwide shift
toward sustainability, the United States alone has witnessed an approximate
50% reduction in coal consumption. Nevertheless, the ample availability
of coal has spurred interest in identifying alternative sustainable
applications. This research delves into the feasibility of utilizing
coal as a nonconventional carbon-rich reinforcement in direct ink
writing (DIW)-based 3D printing techniques. Our investigation here
involves a thermosetting resin serving as a matrix, incorporating
pulverized coal (250 μm in size) and carbon black as the reinforcement
and a viscosity modifier, respectively. The ink formulation is meticulously
designed to exhibit shear-thinning behavior essential for DIW 3D printing,
ensuring uniform and continuous printing. Mechanical properties are
assessed through the 3D printing of ASTM standard specimens to validate
the reinforcing impact. Remarkably, the study reveals that a 2 wt
% coal concentration in the ink leads to a substantial improvement
in both tensile and flexural properties, resulting in enhancements
of 35 and 12.5%, respectively. Additionally, the research demonstrates
the printability of various geometries with coal as reinforcement,
opening up new possibilities for coal utilization while pursuing more
sustainable manufacturing and applications.