If you’re familiar at all with Kapton, you may know it as its tape form. Kapton Tape is used commonly in electrical applications and is known for being able to hold up in extremely high or low temperatures – from about -450º to 500ºF. The material itself, a foil-like polyimide, possesses excellent thermal and chemical stability and so is often used as external insulation that wraps spacecraft, satellites, and planetary rovers. It’s also used to make insulating blankets.
Kapton’s molecular structure is made up of carbons and hydrogens inside benzene rings, giving it its strong thermal and chemical properties but also making it difficult to produce except for in very thin sheets. That’s changing now, though, because a group of researchers at Virginia Tech have figured out how to 3D print Kapton.
Over the course of a year, researchers from the school’s College of Engineering and College of Science managed to synthesize the macromolecules, letting them remain stable and retain their thermal properties while being 3D printed. Chemistry Professor Timothy Long, director of the Macromolecules Innovation Institute (MII), and Maruti Hegde, then a postdoctoral researcher (now a research assistant at the University of North Carolina at Chapel Hill), were looking into the idea of 3D printing aromatic polymers like Kapton. Assisted by a graduate student team, the researchers were able to derive the novel polymer synthesis design and allow the polyimide to be 3D printed.
Associate Mechanical Engineering Professor Christopher Williams, who is also Associate Director of MII and leader of the Design, Research and Education for Additive Manufacturing Systems (DREAMS) Laboratory, worked with his lab, led by graduate students Viswanath Meenakshisundaram and Nicholas Chartrain, to exact the process for 3D printing.
“A rewarding part of this research has been working with the terrific students that helped enable this discovery. It has been fun to watch the Chemists (Maruti Hegde) learn the vocabulary of the additive manufacturing students (Nick Chartrain and Viswanath Meenakshisundaram), and vice versa. I think these types of students are the future of additive manufacturing,” Williams told 3DPrint.com.
“They have developed a skillset in both materials science / chemistry and manufacturing, which I believe represents the future of the additive manufacturing workforce; you need both skillsets to address the critical gaps present in the field today.”
Most 3D printable polymers tend to lose their mechanical strength at around 300°F, but the 3D printed Kapton can maintain its properties above 680ºF – and its heat-resistant ceiling before degradation is 1020ºF. Addtionally, the 3D printed Kapton is just as strong as its thin film counterpart, and can potentially be 3D printed into any shape or size.
“We can imagine this being used for printing a satellite structure, serving as a high-temp filter or a high-temp flow nozzle,” said Williams. “We can imagine using the wide geometric and microscale possibilities offered by 3-D printing to further improve existing designs – say, a more lightweight satellite, a filter that provides optimum/efficient flow, a nozzle with a designed flow path that allows greater exit velocity and efficiency.”
Williams and Long have worked together on several projects involving 3D printing, and have made several advances including:
- An ionically conductive SLA material
- A water-soluble low temperature extrusion material
- A biodegradable SLA polymer for tissue scaffolds
Their work with 3D printable Kapton was recently published in a paper entitled “3D Printing All-Aromatic Polyimides using Mask-Projection Stereolithography: Processing the Nonprocessable,” which you can access here.
“Fundamentally we want to answer the research question, ‘what makes a material printable?’; along the way, we want to continue to add to the materials portfolio of the technologies,” Williams told us.
“Our approach is very integrated and concurrent; it’s not just ‘passing material from lab to the next.’ Tim’s lab and my lab are in constant communication throughout the discovery process; we are going back and forth with our understanding of how the material should be tuned for the process, and how the process should be tuned for the material. They are extremely coupled; they cannot be separated. We have coined this concurrent design of materials and printing processes, ‘Molecules to Manufacturing.'”
The applications of 3D printed Kapton go beyond outer space and could potentially include printed electronics and other applications that require extreme temperature-resistant materials. The researchers have filed a US patent for the 3D printable Kapton and have already been receiving interest from several companies. Discuss in the Virginia Tech forum at 3DPB.com.