Session: 16-01-01: Government Agency Student Poster Competition

Paper Number: 150814

150814 - Improving Interfacial Bonding of 3d Printed Composite Parts Using Integrated Thermoplastic Particles 

Additive manufacturing has recently reshaped the approach to creation of high- fidelity products and rapid prototyping within academia and industry sectors. One of the most exciting burgeoning fields within the vast world of additive manufacturing is direct ink writing of thermoset polymer inks. Thermoset polymer resin systems have been printed on their own with tunable properties and various applications, but these inks are now also being used as a matrix material for fiber- reinforced polymer composites that can be manufactured into high- fidelity parts in less time and with more structural complexity than the traditional composite manufacturing methods. One of the challenges in additive manufacturing of polymers and fiber-reinforced polymer composites is the relatively weak interfacial bonding between printed layers. In traditional bulk manufacturing of polymers and composites, self-remending and self-healing concepts have been used to improve the fracture behavior and longevity of materials. The goal of this project is to adopt and integrate the concept of self-remending in the additive manufacturing of fiber-reinforced thermoset polymer composites. Fine thermoplastic particles are mixed with a high-temperature-cure thermoset composite ink, which can bond to the previously printed layer at the high print temperature due to the softening or melting of the thermoplastic material. This novel approach is expected to not only improve the interlayer bonding but also impart self-healing functionality to the printed composite material. The self-remending element chosen for this study is poly(ethylene-co-methacrylic acid) (EMAA), which is a commonly used copolymer that exhibits the desired remending properties in neat films. The thermoset composite ink cures rapidly via local thermal processing during the additive manufacturing process using a local laser source, enabling high-fidelity manufacturing of parts without the need for bulk curing, which is used in other common methods (e.g., VAT polymerization, UV-curing printing of composites). In this study, fine thermoplastic particles are prepared and mixed with the composite ink at various concentrations. Tensile testing is used to measure the interlayer bond strength in printed composites and to understand the effect of various processing parameters, including print temperature, extrusion rate, and method of introducing heat to the EMAA particles, and their effect on the performance of printed composite parts. One of the key research questions that this study aims to address is the relationship between the size and concentration of particles and the mechanical properties of composites. In particular, the study seeks to determine the optimal particle content and size that will improve the interlayer bonding strength without significant reduction in the overall mechanical properties of the printed composites. 

 

Presenting Author: Erik Christoffersen Colorado State University

Presenting Author Biography: My name is Erik Christoffersen, and I am an undergraduate researcher at Colorado State University who has had the absolute pleasure of working in Dr. Mostafa Yourdkhani's Multifunctional Polymers and Composites Laboratory. In May of 2025, I will be graduating with a bachelor's degree in biomedical engineering and an additional bachelor's degree in mechanical engineering, after which I plan to pursue a Master's of Science in Bioengineering at CSU. Through my journey through engineering and academic research, I have worked in several labs involved in the burgeoning field of biomaterials and tissue engineering. Currently, I am focused on the application and use of tunable thermoset polymers in conjunction with frontal polymerization and direct ink writing to create new methods of manufacturing high fidelity parts with a wide range of applications inside and outside of the biomedical field.

Authors:

Erik Christoffersen Colorado State University
Mostafa Yourdkhani Colorado State University