Rubber ink formulations with high solid content for direct-ink write process

Abstract

Additive manufacturing (AM) is a potential technology for future applications such as smart devices and airless tires. Natural rubber, which is used with restricted processing methods in the tire industry, has drawbacks for use in AM technology because of the high pressure and temperatures required to process it. The motivation of this study is to determine if natural rubber can be used as a 3D printable material. To this end, natural rubber latex (NL) was used as the basis for a printable ink. Liquid rubber was introduced to the NL in various amounts to increase the amount of solid in the ink so as to improve its 3D printability and prevent shrinkage, and sulfur and other additives were incorporated into the mixture to facilitate vulcanization. The rheological properties of inks were investigated for consistent extrusion as well as for shape retention in the printed parts. Dimensional accuracy, printability, and mechanical properties of 3D printed specimens have been investigated. Using a direct-print AM system and the developed rubber ink, various 3D structures were fabricated to demonstrate that the developed ink could be a candidate for future rubber applications.