Low temperature graphitization of interphase polyacrylonitrile (PAN)

Abstract

A B S T R A C TOrdered polyacrylonitrile (PAN) interphase structures were formed in solution-cast PAN/carbon nanotube (CNT) composite films by enhancing polymer crystallization conditions and processing parameters for five types of CNTs. All film samples were heat-treated using similar stabilization and carbonization (up to 1100°C) processes. Both the precursor and carbonized materials were characterized by electron microscopy and X-ray spectroscopy. Highly ordered graphitic structure was formed predominantly in the carbonized materials at 1100°C (i.e., 1500°C lower than the temperature used in a commercial graphitization process). The ordering of the graphite structure formed at 1100°C was further improved by heat treatment up to 2100°C. Multiple characterization results indicate that the early onset of PAN conversion to graphite is directly related to the polymer interphase formation as well as the CNT type. Based on the stabilization and carbonization parameters used in this study, PAN/single-wall carbon nanotube (SWNT) samples showed more prevalent graphite formation at 1100°C. This work demonstrates the influence of CNT type regarding interfacial confinement toward this low-temperature polymer-to-graphite conversion process.

Electrospun 3D Structured Carbon Current Collector for Li/S Batteries

“…With the increase of heating temperature, the intensity and sharpness of this peak gradually raised, suggesting the aromatic layers growth and an increased ordering between the graphitic layers [45]. It is known that the degree of graphitization rises with temperature [46,47], which is also confirmed by the sharp peak appeared at~26.8 • attributed to the (002) reflection of hexagonal graphite at carbonization temperature 800 • C. This can also be observed from the results of Raman spectroscopy, which is another effective tool for micro structural analysis of carbon based materials [48]. The Raman spectra of cPAN CNFs with the final carbonization temperatures of 600, 700 and 800 • C are presented in Figure 3b-d. For carbonized NFs it consists of three dominant peaks assigned to D, D' and G bands, as shown in curve-fitting of the peaks of Raman spectra.…”

Effect of interfacial chemistry on crystallization of polypropylene/multiwall carbon nanotube nanocomposites

“…Among these fillers, carbon nanotubes (CNTs) have captured a great amount of attention due to their outstanding tensile modulus (270-950 GPa) [1], tensile strength [1], thermal (200-3,000 W/m/K at 300 K) [2][3][4] and electrical conductivity (10 2 -10 7 S/m at 300 K) [5], high aspect ratio [6], and role as viscosity modifier [7]. CNTs also act as nucleating agent for polymer crystallization [8][9][10][11][12][13][14] and have the potential for templating polymer interphase including ordered graphitic structure [15][16][17], as well as nanohybrid shish kebab [18,19] and transcrystalline structures [20][21][22].…”

Effect of Pyrolysis Temperature on the Electrical Property and Photosensitivity of a PAN-PMMA Derived Carbon Fiber

“…The studies of heat treatment on PAN focus on two major categories, i.e., low temperature thermal oxidative stabilization [26][27][28][29][30] and high temperature carbonization [31][32][33][34]. Low temperature treatment of PAN refers to the temperature range from room temperature up to 300 • C [26,27].…”

“…The temperature range for the pre-carbonization of PAN-based carbon fiber is from 350 • C to 600 • C [28]. High temperature carbonization typically refers to the treatment in the temperature range from 800 • C to 1300 • C and graphitization of the fiber is in the temperature range from 1300 • C up to 2100 • C [29]. The change in structure of the polymer is significantly affected by various factors in this temperature range.…”