STABILIZATION OF POLY (ACRYLONITRILE-CO-ITACONIC ACID) UNDER AIR CONDITION AS STUDIED BY SOLID-STATE NMR

Bibliographic Details
Main Author:	Tang, Yijing
Language:	English
Published:	University of Akron / OhioLINK 2020
Subjects:	Polymers
Online Access:	http://rave.ohiolink.edu/etdc/view?acc_num=akron1589558728161244

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spelling	ndltd-OhioLink-oai-etd.ohiolink.edu-akron15895587281612442021-08-03T07:15:01Z STABILIZATION OF POLY (ACRYLONITRILE-CO-ITACONIC ACID) UNDER AIR CONDITION AS STUDIED BY SOLID-STATE NMR Tang, Yijing Polymers Stabilization process of Poly(acrylonitrile) (PAN) is one of important steps to make industrially important carbon-fiber materials. In DSC measurement, PAN shows one broad exothermic peak at around 310 C while poly (acrylonitrile-co-itaconic acid) (PAI) gives doublet peaks at 250C and 320C. Understanding lower exothermic peak at the molecular scale is one of the important subjects in industrially important polymer. However, characterization of complex chemical reactions in the early stage is still challenging in all kind of characterization techniques. In this thesis, advanced solid-state nuclear magnetic resonance (ss-NMR) spectroscopy combined with 13C selective isotope labeling method is employed for the quantitative tracking of the structural evolution of PAI with 3% itaconic acid (IA) during the thermal oxidative stabilization (TOS). 13C selective isotope labeling technique significantly enhances NMR sensitivity and allows us to quantitatively analyze chemical structures of PAN and PAI stabilized under air even in the early stage. Two-dimensional (2D) refocused 13C-13C INADEQUATE combined with 30 % 13C three-sites (C3) labeled PAI which can provide the 13C-13C chemical bond correlations, is used to enhance spectral resolutions of the NMR signals and successfully separated chemical reactions of cyclization, aromatization, oxidization, and dehydrogenation at different spectral positions. Consequently, it is found that cyclization and aromatization initially occur and is followed by oxidization, and dehydrogenation in PAI while all reactions simultaneously occur in PAN. Moreover, single-site 13C CN (C-1) and CH2 (C-3) carbon labeled PAI and PAN could allow us to separately observe temperature effects on cyclization process and stabilization process, respectively. It was demonstrated PAI sample gives significant increasing in cyclization (CI) and stabilization indexes (SI) at the low temperatures compared to those in PAN. Quantitively data analysis of CI and SI indicates that the PAI chemical reactions have spatially heterogeneous two step reactions: IA initially induces cyclization of PAN which is followed by aromatization and oxidization (PAI block) and the remaining part is initiated by both cyclization and dehydrogenation which is followed by aromatization and oxidization (PAN block). Such blocky structures explain the observed doublet DSC exothermic peaks in PAI. 2020-07-15 English text University of Akron / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=akron1589558728161244 http://rave.ohiolink.edu/etdc/view?acc_num=akron1589558728161244 unrestricted This thesis or dissertation is protected by copyright: some rights reserved. It is licensed for use under a Creative Commons license. Specific terms and permissions are available from this document's record in the OhioLINK ETD Center.
collection	NDLTD
language	English
sources	NDLTD
topic	Polymers
spellingShingle	Polymers Tang, Yijing STABILIZATION OF POLY (ACRYLONITRILE-CO-ITACONIC ACID) UNDER AIR CONDITION AS STUDIED BY SOLID-STATE NMR
author	Tang, Yijing
author_facet	Tang, Yijing
author_sort	Tang, Yijing
title	STABILIZATION OF POLY (ACRYLONITRILE-CO-ITACONIC ACID) UNDER AIR CONDITION AS STUDIED BY SOLID-STATE NMR
title_short	STABILIZATION OF POLY (ACRYLONITRILE-CO-ITACONIC ACID) UNDER AIR CONDITION AS STUDIED BY SOLID-STATE NMR
title_full	STABILIZATION OF POLY (ACRYLONITRILE-CO-ITACONIC ACID) UNDER AIR CONDITION AS STUDIED BY SOLID-STATE NMR
title_fullStr	STABILIZATION OF POLY (ACRYLONITRILE-CO-ITACONIC ACID) UNDER AIR CONDITION AS STUDIED BY SOLID-STATE NMR
title_full_unstemmed	STABILIZATION OF POLY (ACRYLONITRILE-CO-ITACONIC ACID) UNDER AIR CONDITION AS STUDIED BY SOLID-STATE NMR
title_sort	stabilization of poly (acrylonitrile-co-itaconic acid) under air condition as studied by solid-state nmr
publisher	University of Akron / OhioLINK
publishDate	2020
url	http://rave.ohiolink.edu/etdc/view?acc_num=akron1589558728161244
work_keys_str_mv	AT tangyijing stabilizationofpolyacrylonitrilecoitaconicacidunderairconditionasstudiedbysolidstatenmr
_version_	1719457309174792192

STABILIZATION OF POLY (ACRYLONITRILE-CO-ITACONIC ACID) UNDER AIR CONDITION AS STUDIED BY SOLID-STATE NMR

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