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Studies of reaction mechanisms during stabilization of electrospun polyacrylonitrile carbon nanofibers
Author(s) -
Barua Bipul,
Saha Mrinal C.
Publication year - 2018
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.24708
Subject(s) - polyacrylonitrile , dehydrogenation , differential scanning calorimetry , materials science , activation energy , shrinkage , polymer chemistry , isothermal process , electrospinning , reaction mechanism , chemical engineering , composite material , chemistry , organic chemistry , polymer , catalysis , thermodynamics , engineering , physics
Various reaction mechanisms such as cyclization, oxidation, dehydrogenation, and crosslinking are studied during stabilization of electrospun polyacrylonitrile nanofibers using different in situ techniques such as differential scanning calorimetry (DSC), shrinkage measurement, and dynamic mechanical analysis (DMA). DSC results show that oxidation preferentially occurs in cyclized structure. It is also found that the cyclization reaction has the highest activation energy followed by oxidation/dehydrogenation and crosslinking reactions. In situ shrinkage measurement and DMA data are used to study the extent of cyclization and cross‐linking reactions, respectively, in air. Comparing the in situ shrinkage measurement with DSC data, it is found that cyclization reaction in air progresses in two different mechanisms such as radical cyclization, which depends only on the temperature and ionic cyclization, which is limited by the rate of oxygen diffusion. It is found that complete cyclization time occurs at about 189 min for isothermal heat treatment at 260°C with 5°C/min ramp, while cross‐linking reaction becomes dominant at 132 min. POLYM. ENG. SCI., 58:1315–1321, 2018. © 2017 Society of Plastics Engineers