Year: 2022
Type: article
Abstract: Carbon nanotube (CNT)-reinforced composites are promising materials for high-performance, lightweight structures; however, homogeneous infiltration of CNTs by a matrix material is necessary to achieve desired mechanical properties. Critical to overcoming this challenge at scale is purification of CNT materials produced by floating-catalyst chemical vapor deposition. Here, we present a hydrothermal processing technique for purification of CNT yarns, wherein as-received material is exposed to superheated, subcritical water in a hydrothermal reactor. This process selectively removes amorphous carbon and acid impurities while preserving the yarn structure. We find this technique to be consistent and tunable, with processing time directly correlating to linear density reduction up to a saturation limit. Using commercially-available yarns, we find that after 4 hours of treatment at 200ºC, the weight loss of the yarn under inert atmosphere is reduced from 12% to 5%, the atomic percentage of oxygen at the surface by 42%, and the I D /I G by 30%. In addition, the yarn specific strength (1.3 N/tex) is preserved, while the specific Young’s modulus is significantly increased by 20% (79 to 95 N/tex). At longer treatment times, we obtain greater purity and higher specific Young’s modulus, but at a substantial reduction in tensile strength, which we hypothesize results from eliminating amorphous carbon toughening CNT bundles. The reported method could be scaled to continuous processing in tandem with post-purification treatments, and appears broadly applicable to different continuous CNT networks.
Source: Carbon Trends
Authors: Michael N. Durso, A. John Hart
Institution: Massachusetts Institute of Technology
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,500
Awards: G1335864876, THE INSTITUTE FOR ULTRA-STRONG COMPOSITES BY COMPUTATIONAL DESIGN (US-COMP) WILL BE FOCUSED ON THE MODELING-DRIVEN DESIGN OF A NEW CLASS OF ULTRA-HIGH-STRENGTH-LIGHTWEIGHT (UHSL) MATERIALS FOR FUTURE MANNED MARS MISSIONS. THESE MATERIALS WILL MEET THE REQUIRED MECHANICAL PERFORMANCE GOALS SET FORTH BY NASA AND EXCEED THOSE EXHIBITED BY CURRENT STATE-OF-THE-ART CARBON-FIBER COMPOSITES. US-COMP S VISION IS TO SERVE AS A FOCAL POINT FOR PARTNERSHIPS BETWEEN NASA OTHER AGENCIES INDUSTRY AND ACADEMIA TO: (1) ENABLE COMPUTATIONALLY-DRIVEN DEVELOPMENT OF CARBON NANOTUBE (CNT)-BASED UHSL STRUCTURAL MATERIALS AND (2) EXPAND THE RESOURCE OF HIGHLY SKILLED ENGINEERS SCIENTISTS AND TECHNOLOGISTS IN THIS EMERGING FIELD TO ENHANCE THE U.S. LEADERSHIP IN CRITICAL LIGHTWEIGHT STRUCTURAL MATERIALS. THIS VISION WILL BE ACHIEVED THROUGH THE FOUR PRINCIPLE OBJECTIVES: ESTABLISH A NEW COMPUTATIONALLY-DRIVEN MATERIAL DESIGN PARADIGM FOR RAPID MATERIAL DEVELOPMENT AND DEPLOYMENT DEVELOP A NOVEL UHSL STRUCTURAL MATERIAL FOR USE IN DEEP SPACE EXPLORATION. THE PANEL-LEVEL TESTS AND DEMONSTRATION OF THE NOVEL MATERIALS WILL BE CARRIED OUT TO MOVE THE DEVELOPED TECHNOLOGY TO A TECHNICAL READINESS LEVEL (TRL) OF 4. DEVELOP NOVEL MODELING PROCESSING AND TESTING TOOLS AND METHODS FOR CNT-BASED COMPOSITE MATERIALS ESTABLISH A POOL OF HIGHLY SKILLED ENGINEERS AND SCIENTISTS TO CONTRIBUTE TO THE MATERIALS DEVELOPMENT WORKFORCE. AN INTERDISCIPLINARY AND DIVERSE TEAM OF RESEARCHERS FROM ACADEMIA INDUSTRY AND NATIONAL LABS WILL PARTICIPATE IN THE PROJECT. THE COMPUTATIONAL DESIGN OF THE MATERIAL WILL BE DRIVEN BY A MODELING EFFORT TO INTEGRATE TOPOLOGICAL OPTIMIZATION ATOMISTIC MODELING MOLECULAR MODELING MESOSCALE MODELING AND CONTINUUM-BASED COMPUTATIONAL MECHANICS. INNOVATIONS IN MATERIALS SYNTHESIS AND MANUFACTURING TECHNIQUES WILL ENSURE THE PERFORMANCE AND SCALE-UP FABRICATION OF AEROSPACE-QUALITY TEST SAMPLES AND PANELS. MULTISCALE TESTING AND CHARACTERIZATION CAPABILITIES WILL BE ESTABLISHED AND INTEGRATED TO VALIDATE THE MODELING AND MANUFACTURING EFFORTS AND TO COMPLETE THE PROOF-OF-CONCEPT CYCLE. PARTICIPATION OF THE INDUSTRIAL PARTNERS WILL PROVIDE AND ENSURE THE SCALABILITY AND AEROSPACE-GRADE QUALITY OF THE DEVELOPED COMPOSITE MATERIAL. THE DEVELOPED MATERIALS AND MATERIALS DEVELOPMENT METHODS WILL HAVE A MAJOR IMPACT ON THE AEROSPACE COMMUNITY. FIRST UHSL MATERIALS WILL BE DEVELOPED WITH THE RIGOROUS STRENGTH MODULUS AND FRACTURE TOUGHNESS PROPERTIES NECESSARY FOR MANNED MARS MISSIONS. SECOND A NEW COMPUTATIONALLY-DRIVEN MATERIALS DESIGN PARADIGM WILL BE ESTABLISHED TO DEVELOP THE UHSL MATERIAL OF INTEREST AND FOR FUTURE RAPID MATERIALS DESIGN AND DEVELOPMENT EFFORTS. THIRD A FUNDAMENTAL UNDERSTANDING OF LOAD TRANSFER AND MULTISCALE FAILURE MECHANISMS OF CNT-BASED COMPOSITE MATERIALS WILL BE ESTABLISHED TO ACHIEVE THEIR THEORETICAL PERFORMANCE. FOURTH A REPRODUCIBLE ENGINEERING PERFORMANCE DATA FROM AEROSPACE-QUALITY AND SCALE-UP PANEL TEST RESULTS BUILDING UPON AEROSPACE-GRADE RESIN SYSTEMS AND HIGH-QUALITY COMMERCIALLY AVAILABLE CNT MATERIALS TO ENSURE SCALABILITY TO CONDUCT ASTM STANDARD TESTS. ANOTHER IMPORTANT EMPHASIS OF THE INSTITUTE WILL BE IN WORKFORCE DEVELOPMENT. STUDENTS WILL BE TRAINED FOR DEVELOPING AND UTILIZING ADVANCED COMPUTATIONAL AND EXPERIMENTAL APPROACHES FOR LIGHTWEIGHT MATERIALS. FUNDS WILL BE RESERVED FOR THE STUDENTS TO HAVE EXTENDED VISITS TO NASA FACILITIES DURING SUMMER MONTHS FOR DIRECT MENTORSHIP BY NASA RESEARCHERS. THESE ACTIVITIES WILL STRENGTHEN THE PARTNERSHIPS BETWEEN THE INSTITUTE MEMBERS AND NASA. WITH THE HELP OF THE HBCU PARTICIPANT (FLORIDA A&M UNIVERSITY) THE INSTITUTE WILL ESTABLISH A DIVERSE GROUP OF BOTH RESEARCHERS AND GRADUATE STUDENTS., G318041215, G3202401936, G391170236, MIT Materials Research Science and Engineering Center - Full Proposal
OpenAlex ID: W4293107959