Ultraviolet‐radiation‐induced graft copolymerization of styrene and acrylonitrile onto cotton cellulose

Abstract

SYNOPSISPhotoinitiated graft copolymerization of the vinyl monomers, styrene and acrylonitrile, onto cotton cellulose was studied using uranyl nitrate and ceric ammonium nitrate as photoinitiators. Uranyl nitrate photoinitiation showed a higher level of grafting for styrene, whereas in the case of acrylonitrile ceric ammonium nitrate was found to be the better photoinitiator. Optimized conditions of grafting, when employed to cotton swollen with sodium hydroxide and zinc chloride, enhanced the graft levels for both monomers. Grafted samples were subjected to thermal analysis, as well as estimation of moisture regain and tenacity. Thermal stability increased, whereas, the moisture regain and tenacity decreased, with the increase in graft add-on in the case of both monomers. Acrylonitrile-grafted cotton showed dyeability with cationic dye that improved with the level of graft add-on. Possible explanations have been given. I NTRO DU CTlO NChemical modification of cotton by grafting reactions with various vinyl monomers provides the potential for significantly altering its physical and mechanical properties. Grafting synthetic polymers onto the cellulosic backbone reduces some of its inherent drawbacks and, in addition, the grafted fiber offers more advantages over those obtained by the physical blending of synthetic fibers with cotton fibers. The low-energy UV radiation process possesses certain advantages like less degradation of the backbone polymer and control over the grafting reaction.Garnett et al.' studied the effect of radiation grafting of styrene onto cellulose in presence of methanol and also in the absence of alcoholic solvents using uranyl nitrate initiator.2 Huang and Chandramouli3 examined structure and properties of cellulose-styrene graft copolymer using ceric ion redox initiation. Similarly, use of inorganic salts has been found to enhance radiation grafting.4 Davis et

Photo‐induced graft copolymerization of acrylonitrile onto sodium salt of partially carboxymethylated guar gum

“…Besides, the observed leveling off of the values of % G beyond 6h could be attributed to a decrease in concentration for both photo‐initiator and monomer, thereby causing a reduction in the number of sites on the backbone available for photo‐grafting as the reaction proceeded. Similar time dependency of grafting yields was reported by other workers …”

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

“…In these studies, however, no systematic characterization of products was reported. It was reported that thermal resistance of the grafted copolymer was improved 18–22. In these studies too, characterization of samples are not enough or thermal analysis data are not fully compared with component homopolymers, i.e., cellulose and polyacrylonitrile.…”

Thermal behavior of some homogeneously polymethyl methacrylate (PMMA)‐grafted high α‐cellulose products

“…Many workers investigated the thermal decomposition behavior of the grafted cellulose products. However, grafting reactions were carried out in heterogeneous3–6 and homogeneous reaction conditions and all the reported homogeneous reactions were investigated in solvent systems like dimethyl sulfoxide and paraformaldehyde (DMSO/PF) 7, 8, 11, 12. It was reported that crystallinity, crystal size, and degree of polymerization of cellulose greatly affect the pyrrolysis kinetics of high α‐cellulose,9, 10, 13 attributed to the synthetic polymer chains hindering the crystallization of cellulose chain.…”