Cellulose nanofibers (CNFs) have been widely studied for their reinforcing potential in high-performance composites. While there are numerous publications on CNF-reinforced composites in a variety of polymer matrices, few have considered the recyclability of such thermoplastic composites and whether the incorporation of CNFs deteriorates or improves their performance upon reprocessing. In this study, two thermoplastic resins, poly(lactic acid) (PLA), and glycol-modified polyethylene terephthalate (PETg), were prepared with CNF reinforcement and thermomechanically recycled to investigate the effect of CNF inclusion on the composite properties after reprocessing as well as their effect on the composites’ number of useful life cycles. Additionally, changes in mechanical, thermal, rheological, molecular, and microstructural properties of the composites and/or base resins were monitored as a function of cycle numbers. As is typical, the polymers’ molecular weight and mechanical performance deteriorated with continued processing. However, the addition of spray dried CNF was found to better maintain the mechanical performance of both polymers throughout multiple recycling steps as compared to neat samples. For example, the tensile strength of PETg with 20 wt% CNF after 6 processing cycles was found to exceed that of virgin neat PETg, and higher loadings of CNF were found to preserve a higher yield strength during multiple rounds of reprocessing compared to PETg composites with lower CNF loadings. Ultimately this study indicates that the addition of CNF to some thermoplastic materials can increase both their sustainability by offsetting the use of high-embodied energy resins and their circularity by enabling performance retention over more use cycles.
Copenhaver, Katie, et al. "Improving the Recyclability of Polymer Composites With Cellulose Nanofibrils." Journal of Polymers and the Environment, vol. 32, May. 2024. https://doi.org/10.1007/s10924-024-03257-x
Copenhaver, Katie, Bista, Bivek, Wang, Lu, Bhagia, Samarthya, Lamm, Meghan, Zhao, Xianhui, Tajvidi, Mehdi, Gramlich, William M., Hubbard, Amber M., Clarkson, Caitlyn, & Gardner, Douglas J. (2024). Improving the Recyclability of Polymer Composites With Cellulose Nanofibrils. Journal of Polymers and the Environment, 32. https://doi.org/10.1007/s10924-024-03257-x
Copenhaver, Katie, Bista, Bivek, Wang, Lu, et al., "Improving the Recyclability of Polymer Composites With Cellulose Nanofibrils," Journal of Polymers and the Environment 32 (2024), https://doi.org/10.1007/s10924-024-03257-x
@article{osti_2376392,
author = {Copenhaver, Katie and Bista, Bivek and Wang, Lu and Bhagia, Samarthya and Lamm, Meghan and Zhao, Xianhui and Tajvidi, Mehdi and Gramlich, William M. and Hubbard, Amber M. and Clarkson, Caitlyn and others},
title = {Improving the Recyclability of Polymer Composites With Cellulose Nanofibrils},
annote = {Cellulose nanofibers (CNFs) have been widely studied for their reinforcing potential in high-performance composites. While there are numerous publications on CNF-reinforced composites in a variety of polymer matrices, few have considered the recyclability of such thermoplastic composites and whether the incorporation of CNFs deteriorates or improves their performance upon reprocessing. In this study, two thermoplastic resins, poly(lactic acid) (PLA), and glycol-modified polyethylene terephthalate (PETg), were prepared with CNF reinforcement and thermomechanically recycled to investigate the effect of CNF inclusion on the composite properties after reprocessing as well as their effect on the composites’ number of useful life cycles. Additionally, changes in mechanical, thermal, rheological, molecular, and microstructural properties of the composites and/or base resins were monitored as a function of cycle numbers. As is typical, the polymers’ molecular weight and mechanical performance deteriorated with continued processing. However, the addition of spray dried CNF was found to better maintain the mechanical performance of both polymers throughout multiple recycling steps as compared to neat samples. For example, the tensile strength of PETg with 20 wt% CNF after 6 processing cycles was found to exceed that of virgin neat PETg, and higher loadings of CNF were found to preserve a higher yield strength during multiple rounds of reprocessing compared to PETg composites with lower CNF loadings. Ultimately this study indicates that the addition of CNF to some thermoplastic materials can increase both their sustainability by offsetting the use of high-embodied energy resins and their circularity by enabling performance retention over more use cycles.},
doi = {10.1007/s10924-024-03257-x},
url = {https://www.osti.gov/biblio/2376392},
journal = {Journal of Polymers and the Environment},
issn = {ISSN 1566-2543},
volume = {32},
place = {United States},
publisher = {Springer Nature},
year = {2024},
month = {05}}
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Manufacturing Demonstration Facility (MDF)
Sponsoring Organization:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Energy Efficiency Office. Advanced Materials & Manufacturing Technologies Office (AMMTO)
Grant/Contract Number:
AC05-00OR22725
OSTI ID:
2376392
Journal Information:
Journal of Polymers and the Environment, Journal Name: Journal of Polymers and the Environment Vol. 32; ISSN 1566-2543
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, Vol. 376, Issue 2112https://doi.org/10.1098/rsta.2017.0040