PDF Publication Title:
Text from PDF Page: 005
Polymers 2021, 13, 4197 5 of 13 Polymers 2021, 13, x FOR PEER REVIEW Both results were attributed to nitrogen and hydrogen loss during the high temperature treatment. The SEM image of the cross section of the carbonized mat is shown in Figure 2iv. TfihbeeCrNsFasrmeartawnadsochmarlayctoeriizendtbeydm.uCltaipvlietsietasckdinugeotfodilffaecrekntosfhceeotnsitnawcthaicmhtohnegfibtehrsefiber are randomly oriented. Cavities due to lack of contact among the fiber sheets gave rise to rise to interconnected pores in the micron range distributed along the section. interconnected pores in the micron range distributed along the section. The proposed complex mechanism of stabilization and carbonization of The proposed complex mechanism of stabilization and carbonization of PAN fibers is is briefly represented in Figure 3. briefly represented in Figure 3. Figure 3. Proposed mechanism for (i) N6, (ii) N5, (iii) NQ and (iv) aromatic rings formation occurring Figure 3. Proposed mechanism for (i) N6, (ii) N5, (iii) NQ and (iv) aromatic rings for during stabilization and carbonization of PAN fibers. ring during stabilization and carbonization of PAN fibers. The thermo oxidative stabilization step in air is usually carried out below 300 ◦C as the Tfihrset stheperwmhiochoexniadbaletsivtheesftoarbmialtiizoantioof na lsatdedperisntrauicrtuirse uthsaut adloleys cnaotrrcioelldaposeut belo during the subsequent thermal treatments. Therefore, this stage controls and drives the the first step which enables the formation of a ladder structure that does not c final mechanical properties of the CNFs, and chemical properties, such as the elemental ing the subsequent thermal treatments. Therefore, this stage controls and dri content of the carbon fibers, might also be influenced by this thermal treatment. After mechanical properties of the CNFs, and chemical properties, such as the eleme stabilization in air, the PAN structure could undergo several modifications due to the oxfidthateiocnaarnbdorneafrirbaenrgse,mmenitgohftnaitlrsiloe gbreouinpsflwuiethntcheedpbroyduthctisonthofecromndaelntsredantmitroegnetn.-After s doped rings (Figure 3i) that could further evolve to N6 moieties [32,35]. Furthermore, in air, the PAN structure could undergo several modifications due to the ox homolytic cleavage of nitrile groups could also lead to the formation of N5 (Figure 3ii) and rearrangement of nitrile groups with the production of condensed nitrogen- NQ (Figure 3iii) structures after dehydrogenation reactions. Interestingly, Grassie et al. [34] (Figure 3i) that could further evolve to N6 moieties [32,35]. Furthermore, hom reported the formation mechanism of carbon rings through the coupling of homolytic nitrile cleavage and heterolytic hydrogen cleavage (Figure 3iv). The occurrence of these age of nitrile groups could also lead to the formation of N5 (Figure 3ii) and mechanisms was supported by the FT-IR spectra, which are shown in Figure 4. 3iii) structures after dehydrogenation reactions. Interestingly, Grassie et al. [ CNFs stabilized at 230 ◦C display a reduction of peak of νCN centred at around the form−1 ation mechanism of carbon rings through the cou−p1 ling of homolytic 2240 cm and a drastic lowering of νC=O peaked at around 1740 cm that was likely daugetoanthdephrestenrcoelyofticcarhboyxdyrliocgadednitcivlesa[v3a9]gient(hFeigcoumrmee3ricvia)l.PTAhNe.Tohcecνurrensicgenaolfatthese CH2 1452 cm−1 is not significantly decreased after 1 h (sample CNF_230) and 2 h of treatment at was supported by the FT-IR spectra, which are shown in Figure 4. 230 ◦C indicating that dehydrogenation was barely initiated. At 260 ◦C, νCN peak intensity is further reduced, suggesting an advanced nitrile groups rearrangement [39] with rising of νC=C and νC=N. Stabilization time seemed to poorly affect PAN when a temperature of up to 230 ◦C is used during the stabilization process, while it became more relevant at 260 ◦C. After 2 h at 260 ◦C, νCN and νCH2 peaks completely disappeared and the neat and nitrogen containing aromatic moieties are massively detected. After the stabilization, the pyrolytic treatment induced the conversion of PAN fibers to CNFs with the disappearing s m w o v n i d o N 3 n mPDF Image | Effect of Thermal Stabilization on PAN-Derived Electrospun Carbon Nanofibers
PDF Search Title:
Effect of Thermal Stabilization on PAN-Derived Electrospun Carbon NanofibersOriginal File Name Searched:
polymers-13-04197-v2.pdfDIY PDF Search: Google It | Yahoo | Bing
Sulfur Deposition on Carbon Nanofibers using Supercritical CO2 Sulfur Deposition on Carbon Nanofibers using Supercritical CO2. Gamma sulfur also known as mother of pearl sulfur and nacreous sulfur... More Info
CO2 Organic Rankine Cycle Experimenter Platform The supercritical CO2 phase change system is both a heat pump and organic rankine cycle which can be used for those purposes and as a supercritical extractor for advanced subcritical and supercritical extraction technology. Uses include producing nanoparticles, precious metal CO2 extraction, lithium battery recycling, and other applications... More Info
CONTACT TEL: 608-238-6001 Email: greg@infinityturbine.com (Standard Web Page)