Study on polyethylene-based carbon fibers obtained by sulfonation under hydrostatic pressure

Abstract

Polyethylene based carbon fibers were studied using high density polyethylene(HDPE) fibers and linear low density polyethylene(LLDPE) fibers with various melt flow index. The draw ratio of the polyethylene fibers and the sulfonation mechanism were investigated under hydrostatic pressures of 1 and 5 bar in the first time. The influence of the melt flow index of polyethylene and types of polyethylene fibers on the sulfonation reaction was studied. Carbon fibers were prepared through the sulfonation of LLDPE fibers possessing side chains with a high melt flow index. The polyethylene fibers, which exhibited thermoplastic properties and plastic behavior, were cross-linked through the sulfonation process. Their thermal properties and mechanical properties changed to thermoset properties and elastic behavior. Although sulfonation was performed under a hydrostatic pressure of 5 bar, it was difficult to convert the highly oriented polyethylene fibers because of their high crystallinity, but partially oriented polyethylene fibers could be converted to carbon fibers. Therefore, the effect of fiber orientation on fiber crosslinking, which has not been reported in previous literature, has been studied in detail, and a new method of hydrostatic pressure sulfonation has been successful in thermally stabilizing polyethylene fiber. Hydrostatic sulfonation was performed using partially oriented LLDPE fibers with a melt flow index of 20 at 130 °C for 2.5 h under a hydrostatic pressure of 5 bar. The resulting fibers were carbonized under the following conditions: 1000 °C, 5 °C/min, and five minutes. Carbon fibers with a tensile strength of 2.03 GPa, a tensile modulus of 143.63 GPa, and an elongation at break of 1.42% were prepared.

Multifunctional Carbon Fibers from Chemical Upcycling of Mask Waste

“…After the reaction for 2 h, the fiber diameter slightly changes to 21.6 μm and remains relatively constant after 12 h of sulfonation. Interestingly, our result varies from a recent work studying a variety of PE-based fibers under similar chemical treatments, which observed that all low-density PE fibers exhibited increases in the fiber diameter at increased reaction times up to 25% of the original diameter . Other works also demonstrate a similar phenomenon in PE fibers under proper reaction conditions. , We attributed this difference to the use of sulfuric acids with different concentrations, where the diluted ones are known to be significantly more reactive than their concentrated counterparts.…”

Upcycling Mask Waste to Carbon Capture Sorbents: A Combined Experimental and Computational Study

“…For all carbonized samples, the averaged fiber diameter is ∼12 μm (Figure (G–J), indicating an ∼25% shrinkage from their original state. The reduced fiber diameter upon carbonization was slightly larger than those from multiple reports that used a similar process to produce carbon fibers from linear low-density PE …”

“…The reduced fiber diameter upon carbonization was slightly larger than those from multiple reports that used a similar process to produce carbon fibers from linear low-density PE. 60 While fibril structures are maintained after cross-linking and carbonization steps, microporosity can be developed within PP-derived carbon. For example, several previous studies found that insufficient cross-linking from a short reaction time can result in hollow carbon fibers.…”

Direct synthesis of ordered mesoporous materials from thermoplastic elastomers

“…PAN-based BCP can result in nitrogen-doped mesoporous carbon with nitrogen content up to 13 at% 22 , enabling their exceptional performance for many applications, such as fast-charging batteries 59 , supercapacitors 60 , and water desalination 61 . Sulfonation-enabled crosslinking of PE and PP can result in high sulfur contents, approaching 3 at% as determined through X-ray photoelectron spectroscopy (XPS) in previous reports 62 . For our system, XPS results (Fig.…”