Cyclization kinetics of gel‐spun polyacrylonitrile/aldaric‐acid sugars using the isoconversional approach. Issue 11 (23rd October 2021)

• Record Type: Journal Article
• Authors: Banerjee, Debjyoti; Dedmon, Hannah; Rahmani, Farzin; Pasquinelli, Melissa; Ford, Ericka
• Is Part Of: Journal of applied polymer science. Volume 139:Issue 11(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-10-23
• Subjects: differential scanning calorimetry -- extrusion -- fibers -- kinetics -- thermal properties; Polymers -- Periodicals; Polymerization -- Periodicals; 668.9
• DOI: 10.1002/app.51781
• Languages: English
• ISSNs: 0021-8995

Abstract

Abstract: Comonomers, such as methacrylic acid, itaconic acid, and acrylic acid, can minimize the activation energy of polyacrylonitrile (PAN) cyclization through their nucleophilic reaction with pendant nitrile groups. An understanding of how these comonomers affect the kinetics of PAN cyclization inspired this study on how the isomeric sugars (glucaric acid( cis ) and mucic acid( trans )) would influence PAN cyclization. Until now, researchers have characterized the cyclization of PAN by single activation energy; however, this approach using differential scanning calorimetry does not represent the conversion dependent kinetics of cyclization. The isoconversional method was used to evaluate exotherms for cyclization at three different heating rates while allowing the calculation of activation energy at incremental increases in conversion ( α ). The aldaric acid sugars reduced the activation energy of initiation by ~five times in comparison to values observed for neat PAN fiber and the ratio of ( k 1 / k 2 ) (where k 1 is the rate constant for initiation and k 2 is the rate constant for propagation) improved by ~2 orders of magnitude. Based on molecular dynamic simulations, hydrogen bonding between the aldaric acids sugars and PAN lowered the activation energy at the onset of cyclization. Abstract :