Unveiling Carbon Ring Structure Formation Mechanisms in Polyacrylonitrile-Derived Carbon Fibers

Abstract

As the demand for electric vehicles (EVs) and autonomous vehicles (AVs) rapidly grows, lower-cost, lighter, and stronger carbon fibers (CFs) are urgently needed to respond to consumers’ call for greater EV traveling range and stronger safety structures for AVs. Converting polymeric precursors to CFs requires a complex set of thermochemical processes; a systematic understanding of each parameter in fiber conversion is still, to a large extent, lacking. Here, we demonstrate the effect of carbonization temperature on carbon ring structure formation by combining atomistic/microscale simulations and experimental validation. Experimental testing, as predicted by simulations, exhibited that the strength and ductility of PAN CFs decreased, whereas the Young’s modulus increased with increasing carbonization temperature. Our simulations unveiled that high carbonization temperature accelerated the kinetics of graphitic phase nucleation and growth, leading to the decrease in strength and ductility but increase in modulus. The methodology presented herein using combined atomistic/microscale simulations and experimental validation lays a firm foundation for further innovation in CF manufacturing and low-cost alternative precursor development.

A Molecular Dynamics Study of the Stability and Mechanical Properties of a Nano-Engineered Fuzzy Carbon Fiber Composite

“…The larger pores in experimental samples act as stress concentration sites and thus lead to brittle fracture and lower strength. Moreover, the published work of computational large-scale carbon fiber microstructure stress-strain curves by Zhu et al [25] for three different structures have resulted in a comparable range of strength values between 6.73-6.90 GPa and Young's modulus of 95.9-284.5 GPa. Last, the simulated CF models showed crystallite arrangement around the longitudinal axis with turbostratic stacks of graphite structure, as shown in Figures S6-S9.…”

“…Several atomistic approaches and computational tools were used to generate 2D and 3D microstructures of CF. The simulations range from surface studies with simplified graphene layers [20][21][22] and graphite blocks annealing [23] to complex precursor and reactive simulations [24,25] for the analysis of CF chemistry and mechanical properties. Therefore, an MD simulation (See Section 2.2.1) was used to model the range of CF microstructures with varied degrees of graphitic region.…”

Microstructure Evolution and Its Correlation with Performance in Nitrogen-Containing Porous Carbon Prepared by Polypyrrole Carbonization: Insights from Hybrid Calculations

“…The ReaxFF C-2019 potential [ 45 ] was applied to the simulation process. ReaxFF C-2019 was developed to characterize the dissociation and formation of chemical bonds; thus, it was believed to be a suitable forcefield for the previous study of polymer precursors [ 46 , 47 ] and the current investigation of PPy carbonization.…”

Computational study of the effect of core–skin structure on the mechanical properties of carbon nanofibers

“…The mechanical properties of CNFs with and without the graphitic skin layer are investigated in this study using large-scale molecular dynamics (MD) simulations. This computational technique has been successfully applied to analysis of chemical reactions leading to the formation of carbon fiber microstructure from molecular precursors [25][26][27][28][29][30][31][32], oxidation of carbon fibers [33], as well as the elementary processes involved in mechanical deformation of carbon fibers [27,28,[34][35][36][37]. The high computational cost of MD simulations, however, prevents application of this technique for direct evaluation of the mechanical properties of fibers with heterogeneous microstructure, such as the ones of core-skin carbon fibers.…”

“…The tensile testing simulations are performed with a more computationally expensive [43] ReaxFF interatomic potential [29,44,45], which provides a more realistic, as compared to the AIREBO-M potential, description of the bond rearrangement and scission during the irreversible (plastic) deformation and fracture (see Supplementary Information for additional discussion of problems preventing the use of AIREBO-M in the simulations of fracture of carbon nanofibers). The ReaxFF force field used in this paper is parameterized for C/H/O/N chemistry [29] and has been successfully applied to simulation of different steps in the carbon fiber formation [28][29][30][31].…”