Characterization and thermal stability of cellulose‐graft‐polyacryloniytrile prepared by using KMnO₄/citric acid redox system

Abstract

An effective condition of graft polymerization of acrylonitrile onto cellulose fiber in large volume of KMnO 4 /citric acid aqueous solution was examined and the produced grafted copolymers were characterized by using SEM, NMR, FTIR, XRD, TGA, and DSC in comparison with component homopolymers. Graft yield, GY, obtained by simple weighting method was close to the value obtained by NMR analysis. Significant change of chemical structure in cellulose fiber, other than graft reaction, was not detected by NMR and FTIR measurements, whereas a decrease in the degree of crystallinity by the reaction was detected by XRD measurement. It was pointed out that thermograms for grafted samples resembles with that of cellulose at T < 370 C and become similar with that for polyacrylonitrile at T > 370 C and the mass of residue at 550 C is proportional to the content of polyacrylonitrile (GY) only. It is concluded that thermal decomposition of both polymers occurs almost independently in grafted polymers and thermal stability of cellulose fiber is not improved.

Characterization and Mechanical Properties of Cellulose-graft-Polyacrylonitrile Prepared by Using KMnO4/different Acids as Redox System

“…Figure 4 shows the 13 C CP-MAS spectra of Un-C and C-g-PAN samples prepared by using different acids in the graft copolymerization. As reported in the previous study 29) , the resonances belonging to the cellulose (60-110 ppm) are well observed in the all spectra. Also the resonance peaks related to the grafted chain (40 ppm) are observed in the all spectra of C-g-PAN samples.…”

“…As reported previously 29) , the grafted-PAN only partially covered the cellulose surface so that the morphological characteristics of cellulose microfibrils are still visible in the grafted samples.…”

“…In the previous study 29) , we prepared cellulose-graftpolyacrylonitrile (C-g-PAN) using KMnO 4 /citric acid redox system and characterized the obtained samples by SEM, FT-IR, 13 C-NMR, XRD, TGA, and DSC. We reported that graft yield percentage is controllable but since cellulose fiber surface is only partially covered by PAN so that thermal stability of cellulose is not improved by grafting PAN.…”

“…By fixing the amount of materials, cellulose : liquid (M : L (by wt : vol)) = 1 : 100 as same in the previous study 29) , graft copolymerization of pre-treated cotton cellulose was carried out in a reaction flask kept in a thermostatic water bath by using the most efficient condition as following values (e. g. C-g-PAN48 for sample with GY = 48 %).…”

“…[8][9][10][11][12][13][14] Acrylonitrile (AN) is the most frequently tested monomer due to its highest efficiency 15,16) and possibility for further modification such as alkaline hydrolysis. 15,17) For example, the acrylonitrile grafted sample can be amidoximated to use in the metal ion adsorption [18][19][20][21] and expected to be used as antimicrobial materials. 22) Graft copolymerization reactions onto cotton cellulose with acrylonitrile have been studied using different initiation techniques, viz., manganese, sulphate initiation 23) , ozonization 24) , plasma radiation 25) , Co-60-γ-ray radiation 26) , and so on.…”