Session: 03-05-03: Design, Material Processing, and Applications of Metal and Ceramic Composites

Paper Number: 95772

95772 - Cellulose Nanofibers (CNF)/Carbon Fiber Composites With Enhanced Flexural Strength for Structural Applications 

Cellulose Nanofibers (CNF) are produced from plant cellulose microfibers through a facile synthesis process. These fibers are discontinuous, highly graphitic, highly compatible with most polymer processing techniques, and they can be dispersed in an isotropic or anisotropic mode. Since they are available in a free-flowing powder form, the dry carbon fiber can be physically modified with the addition of CNF. The effect of the CNF compositions, their morphology on carbon fiber, and subsequent mechanical properties are explored in this paper. The CNF composite nanofiber networks are introduced as interleave layers to improve the interlaminar shear strength (ILSS) of an epoxy/carbon fiber laminate composite. A solvent exchange process is utilized to disperse CNF in an adequate solvent for the ease of coating the surface of the carbon fiber followed by probe sonication. Square-sized dry carbon fiber is cut with precise dimensions of 8 inches by 8 inches. Dry carbon fiber is coated by different volume fractions of CNF (0.6 wt.%, 0.8 wt.%, 1 wt.%) through the strong bath sonication process. Then the CNFs volume fraction and fracture properties of enhanced carbon fiber reinforced polymer (CFRP) laminates are studied extensively. After the annealing process, 8 layers of CNF coated carbon fibers are stacked and infused with epoxy resin through the vacuum assisted resin transfer molding (VARTM) method under high pressure followed by a curing process in an oven. It is shown that when the dry carbon fiber is treated with CNF, the laminate shows greater mechanical strength in certain cases. Laminates are fabricated by modifying dry carbon fiber surface with CNF results in a considerable improvement in the mechanical characteristics of the random composite nanofiber networks as compared to a neat sample. The application of CNF composite nanofiber networks as an interleaved layer in an epoxy/carbon laminate increases the delamination resistance of the ILSS in both 0.8wt% and 1 wt.% CNF by 36% and 25% respectively, but no significant difference is found for ILSS in 0.6 wt.% CNF. It is found that the addition of 0.8 wt.% and 1 wt.% CNF to the dry carbon fiber results in 27.2%, 12.4% increment respectively, in short beam shear (SBS) strength while comparing to the neat control sample. It is observed by testing for the mechanical strength of these laminates, the neat sample reached a maximum load of 978N and then plummets. The addition of 0.8 wt.% CNF to the carbon fiber adds to the maximum load-bearing capacity of the laminate up to 1338N. Moreover, a significant improvement is observed in flexural modulus for 0.8 wt.% CNF coated carbon fiber laminate. This result suggests that CNF can enhance the delamination resistance of an epoxy/carbon laminate undergoing ILSS and deformation. This result is attributed to crack path modification, and load energy absorption by higher modulus CNFs reinforced nanofibers interleave in the laminate resulting in a higher shear modulus to the networks.

Presenting Author: Siddharth Bhaganagar Indiana University Purdue University-Indianapolis

Presenting Author Biography: Siddharth Bhaganagar is doing MS in Motorsports Engineering at Indiana University Purdue University-Indianapolis. He has been working on carbon cellulose nanocrystals and cellulose nanofiber based epoxy composites since Fall 2021.

Authors:

Siddharth Bhaganagar Indiana University Purdue University-Indianapolis
Pias Kumar Biswas Indiana University − Purdue University Indianapolis
Mangilal Agarwal Indiana University Purdue University-Indianapolis
Hamid Dalir Indiana University Purdue University-Indianapolis