Effect of Allyl Acrylate on the Thermal Stability of PAN Precursor for Carbon Fibers

The thermal management of polyacrylonitrile (PAN) precursors during thermo-oxidative stabilization (TOS) presents a significant challenge in carbon fiber (CF) manufacturing, primarily due to intense and localized exothermic reactions that can lead to structural defects. To mitigate this issue, the present work by proposing allyl acrylate (ALA) as ester-functional comonomer for precursor modification. A series of terpolymers poly (acrylonitrile-itaconic acid-allyl acrylate) [P(AN-IA-ALA)] with varied ALA content were synthesized through solution-based free radical polymerization. Comprehensive characterization were conducted to elucidate the role of ALA in precursor properties. XRD results demonstrate that ALA incorporation perturbs molecular chain ordering, resulting in reduced crystallinity. FT-IR spectroscopy further verifies that ALA markedly facilitates the TOS process, promoting the formation of cyclic ladder structures and enhancing the overall cyclization degree. According to the DSC and TGA reveal that, relative to the PAN homopolymer, the terpolymer undergoes cyclization at a lower initiate temperature, exhibits a broadened and attenuated exothermic profile, and presents a reduced activation energy for cyclization. Collectively, these enhancements translate into significantly improved stabilization characteristics, indicating that the P(AN-IA-ALA) is a potential candidate for use as a potential PAN-based precursor candidate. Graphical The thermal management of polyacrylonitrile (PAN) precursors during thermo-oxidative stabilization (TOS) presents a significant challenge in carbon fiber (CF) manufacturing, primarily due to intense and localized exothermic reactions that can lead to structural defects. To mitigate this issue, the present work by proposing allyl acrylate (ALA) as ester-functional comonomer for precursor modification. A series of terpolymers poly (acrylonitrile-itaconic acid-allyl acrylate) [P(AN-IA-ALA)] with varied ALA content were synthesized through solution-based free radical polymerization. Comprehensive characterization were conducted to elucidate the role of ALA in precursor properties. XRD results demonstrate that ALA incorporation perturbs molecular chain ordering, resulting in reduced crystallinity. FT-IR spectroscopy further verifies that ALA markedly facilitates the TOS process, promoting the formation of cyclic ladder structures and enhancing the overall cyclization degree. According to the DSC and TGA reveal that, relative to the PAN homopolymer, the terpolymer undergoes cyclization at a lower initiate temperature, exhibits a broadened and attenuated exothermic profile, and presents a reduced activation energy for cyclization. Collectively, these enhancements translate into significantly improved stabilization characteristics, indicating that the P(AN-IA-ALA) is a potential candidate for use as a potential PAN-based precursor candidate.