ABSTRACT KEARNS, ALEXA JO. Cotton Cellulose Fibers for 3D Print Material. (Under the direction of Dr. Jesse S. Jur and Dr. Richard Venditti). Consumers often desire clean, energy efficient and sustainable solutions to many societal obstacles, including the production of consumer good from the manufacturing sector. New products advocating environmental consciousness and supporting modern consumerism must maintain consistent mechanical and optical properties aligned with those found in petroleum- based materials while lowering energy consumption and retaining biodegradable properties. Manufacturing typically uses subtractive techniques where raw material is milled into the desired product shapes. However, the additive manufacturing sector has garnered attention for its ability to generate products with a range of materials and surface finishes while minimizing use of raw materials. The structures developed with additive manufacturing allow for customization and localized printing, along with reducing costs and transportation energy. This research focuses on fused deposition modeling (FDM), where products develop by layering molten filament upon previously laid and cooled material. Neat polymers, such as poly(lactic) acid (PLA), are frequently used as filament and have virtuous mechanical properties, such as tensile and compressive strength, that allow for substitution with petroleum based products. Adding reinforcing fibers to bridgeable polymer filaments has the potential to increase mechanical properties and expand the prospective applications of additive manufacturing. Initial research considered filaments with plant-based fiber reinforcement as benchmark materials to compare against neat PLA polymer filament and prints. Filament is the material used for FDM printing and can be found a wide variety of materials. Through compression and tensile testing with cross sectional x shapes, filament segments, and dog-bone prints, each filament varied in strength and showed a difference in mechanical properties with the same fiber reinforcement but different manufacturers. Predictably, neat PLA proved to have the strongest mechanical properties, further confirmation with SEM images show more uniformed cross sections as compared to the plant-based filaments. This research focused on the utilization of recycled cotton t-shirts as fiber reinforcing elements for polymer filaments. The first experiment compounded pulverized cotton cellulose fibers (pCot) with low density polyethylene (LDPE). Extrusion at 185 ℃ into filament form left a brittle and rough material with low mechanical properties that easily broke when used with a Lulzbot TAZ 5 3D printer. At 210 ℃ the filament could extrude through the 3D printer, but was not able to adequately bond with the print bed or subsequent layers of material. Research continued with poly(lactic) acid (PLA) pellets, after LDPE/ pCot composite filament was deemed an inadequate 3D print material. Compounding of PLA and pCot occurred in a twin screw extruder, and then developed into filament with a Noztek pro HT extruder. A maximum loading of 31 weight percent (wt%) cotton extruded, but was judged too brittle for 3D printing. c2renew developed a cotton loaded filament with of 10 wt%, 15 wt%, and 20 wt% and 1% lubrication. These filaments could consistently extrude through the 3D printer and bond on the print bed and subsequently extruded material. Mechanical analysis showed the PLA/ pCot being substantially weaker than benchmarked materials, but stronger than the LPDE/ pCot filament. Filaments for fused deposition modeling can be constructed using biodegradable polymers and plant-based fibers with the intention of replacing petroleum based manufacturing materials and practices. Cotton fibers from pulverized waste cotton t-shirts can be compounded with PLA as a reinforcing agent. This research explored compounding with PLA and LDPE to create a professional grade filament. The loading content and the ability to dissolve polymer for recycling were also investigated. © Copyright 2017 Alexa Jo Kearns All Rights Reserved Cotton Cellulose Fibers in 3D Print Material by Alexa Jo Kearns A thesis submitted to the Graduate Faculty of North Carolina State University in partial fulfillment of the requirements for the degree of Master of Science Textile Engineering Raleigh, North Carolina 2017 APPROVED BY: _______________________________ _______________________________ Dr. Jesse S. Jur Dr. Richard Venditti Committee Co-Chair Committee Co-Chair _______________________________ Dr. Russell E. Gorga BIOGRAPHY Alexa Kearns was born and raised in Portland, Oregon. She was involved in cross country, swimming, and track, eventually earning a scholarship to Northern Arizona University in Flagstaff, Az. After a year, Kearns switched focus from athletics to her engineering degree. In 2014, she graduated with her Bachelor of Science degree in mechanical engineering from Northern Arizona University. In August of 2015, Kearns entered the NC State University College of Textiles under the direction of Dr. Jesse Jur and Dr. Richard Venditti. She studied the 3D printing capabilities, parameters, and sustainability of cotton and graduated in May 2017 with her MS in textile engineering. In her spare time, Kearns enjoys participating in the NC State club triathlon team and exploring North Carolina. ii ACKNOWLEDGMENTS I would like to sincerely thank Dr. Jesse S. Jur from NC State’s College of Textiles for his advisement and financial support. His guidance and encouragement were paramount in accomplishing my research. Additionally, I would like to acknowledge my appreciation for Dr. Richard Venditti from NC State’s College of Natural Resources. His encouragement and belief in my research helped overcome many obstacles and challenges. I also am grateful for Dr. Russell Gorga for his continual support and opening his lab for testing. This project would not be possible without the financial support and guidance of Janet O'Regan of Cotton Incorporated. I would like to express my gratitude to the Cotton Incorporated team working with NC State on this project. Finally, I would like to thank and acknowledge my research group, Amanda Myers, Wade Ingram, Raj Bhakta, Hasan Shahariar, Nate Weiner, Cemile, Aksu, Lanjun Yin, Allison Bowles, and Jack Twiddy. I will forever cherish their unwavering support and friendship. iii TABLE OF CONTENTS LIST OF TABLES ................................................................................................................. vi LIST OF FIGURES ............................................................................................................. viii 1.0 INTRODUCTION........................................................................................................ 1 2.0 LITERATURE REVIEW ................................................................................................ 4 2.1 3D PRINT OVERVIEW ................................................................................................. 4 2.1.1 ADDITIVE MANUFACTURING TECHNOLOGY .............................................. 5 2.1.2 SUSTAINABILITY ............................................................................................... 15 2.1.3 THE SOCIETAL IMPACT OF ADDITIVE MANUFACTURING ..................... 19 2.2 COTTON ...................................................................................................................... 20 2.2.1 COTTON MOTIVATION ......................................................................................... 20 2.2.1 INTRODUCTION TO CELLULOSE ................................................................... 24 2.2.2 COTTON CELLULOSE ....................................................................................... 25 2.2.3 COTTON MORPHOLOGY .................................................................................. 28 2.2.4 COMPOUNDING WITH COTTON ..................................................................... 30 2.3 3D PRINT POLYMERS ............................................................................................... 31 2.3.1 PRINTING WITH POLYMERS ........................................................................... 31 2.3.2 GREEN POLYMERS ............................................................................................ 32 2.3.3 PLA ........................................................................................................................ 33 3.0 PREVIOUS EFFORTS IN THE FIELD....................................................................... 38 4.0 3D PRINTING OF PLANT-BASED COMPOSITE FILAMENTS .......................... 40 4.1 SUMMARY .................................................................................................................. 40 4.2 INTRODUCTION ........................................................................................................ 40 4.3 EXPERIMENTAL DESIGN ........................................................................................ 43 4.4 RESULTS AND DISCUSSION ................................................................................... 45 4.5 CONCLUSION ............................................................................................................. 52 5.0 PCOT FIBERS IN 3D PRINTING ................................................................................ 54 5.1 SUMMARY .................................................................................................................. 54 5.2 INTRODUCTION .......................................................................................................