Carbon nanofiber (CNF) has long held interest as a potential reinforcement addition for polymer matrices. CNF is ~2000 times smaller than the more commonly known carbon fiber, and benefits from nanoscale effects due to its size. This gives CNF some superior properties such as enhanced stiffness and strength. The CNF structure consists of aromatic carbons in a cone-like shape stacked on top of each other with Van der Waals interactions and π-π interactions maintain the structure. The lack of physical bonds to maintain the fiber structure contributes to the relative physical instability of the CNF, making it expensive to fabricate experimentally. Further, CNF can have many different shapes based on the apex angle of the cone, and perform differently based on the CNF aspect ratio (height:width of the CNF). Molecular Dynamics (MD) provides a pathway to study CNF effects on polymer matrices to elucidate information about interactions between CNF and polymer matrices. Further, similar to other carbon nanostructures, CNF tends to aggregate within polymer matrices limiting the potential of the CNF as a polymer reinforcement. CNF alignment also contributes to the reinforcement potential of the polymer matrix as the CNF mechanical response is dependent on the direction of the force in respect to the orientation of the fiber. Uniform dispersion and orientation are difficult to study experimentally, but are more easily examined via MD. We studied the potential of CNF as a polymer reinforcement for nylon 6 with agglomeration and orientation effects eliminated by studying the effects of increasing CNF concentration on the mechanical properties of a common polymer, nylon 6. A CNF with an apex angle of 112&lt;span style="font-size:10.8333px"&gt; degrees&lt;/span&gt; and an aspect ratio of 5 is used. Interaction studies have shown that CNF significantly prefers to interact with itself more than nylon 6, contributing to the agglomeration difficulties observed experimentally. The Young’s modulus of the nanocomposite increases in agreement with mathematical models, indicating the importance of obtaining uniform dispersion and alignment for CNF polymer reinforcement.

Molecular dynamics study of uniformly dispersed, aligned carbon nanofibers on the material properties of nylon 6

ACS Fall 2021

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