Grafting vinyl polymers onto cellulose by high energy radiation. I. High energy radiation‐induced graft copolymerization of styrene onto cellulose

Abstract

Styrene has been grafted onto cellulose in the form of cotton linters, cotton cloth, and rayon by ionizing radiation. Styrene was brought into intimate contact with cellulose by extension of the “inclusion” technique of Staudinger and Krässig, and graft copolymers were prepared by exposure to high energy electrons or to gamma‐rays from Co60. Substantial grafting was obtained by irradiation in air, nitrogen, or in vacuum. The products were purified by exhaustive extraction with benzene in a Soxhlet apparatus to remove the polystyrene homopolymer. The graft copolymers were characterized by removing the cellulose backbone by hydrolysis and determining the molecular weights of the residual polystyrene. Molecular weights of the grafted polystyrene were found to be considerably higher than those of the extracted homopolymer polystyrene or the polystyrene formed by irradiating styrene in bulk. Calculations based on the molecular weights of cellulose and polystyrene in the graft copolymer indicate that despite the substantial grafting, only one in 5,000–10,000 anhydroglucose units or one in 10–20 cellulose chains carried a grafted polystyrene chain.

Grafting of Flax Fiber (Linum usitatissimum) with Vinyl Monomers for Enhancement of Properties of Flax-Phenolic Composites

“…Therefore, hydroxyl free radicals will prefer to interact with vinyl monomers thereby giving grow-ing polymeric chain which in turn creates sites on flax back-bone by hydrogen abstraction (4). Termination of various active species in the reaction mixture may take place by recombination step (6) and by transfer process (7). The concentration of ferric ions (Fe þ3 ) in the reaction mixture plays an important role in getting the percentage grafting as it is directly involved in the termination of the reaction.…”

“…1 Modifying the properties of natural polymers through graft copolymerization has been reported by various workers. [2][3][4][5][6][7][8][9][10][11][12] The conventional technique of grafting and chemical modification of natural fibers requires significant time and energy. The use of MWR technique to modify the properties of natural fibers within the textile industry, although somewhat slow and still rather limited, is finding its way into numerous uses in production plants.…”

Electron Microscopic Observations on Cellulose Graft Copolymers: Radiation Induced Rayon-Styrene Graft Copolymers1

“…During irradiation, gamma-rays intera~ct with the cellulose backbone to form polymeric free radicals which act as centers of initiation for the graft copolymerization of styrene on to cellulose. Once initiated, the polystyrene grows to very high chain lengths because of, the gel effect in the highly condensed and viscous conditions within the filament [5]. It is obvious here that only those cellulosic free radicals which are acce~5il~le to styrene monomer can be utilized.…”

Microfiltration membranes prepared from poly(N-vinyl-2-pyrrolidone) grafted poly(vinylidene fluoride) synthesized by simultaneous irradiation

“…Because grafting is believed to occur only in amorphous regions, the number of grafts per polymer chain seldom exceeds unity in a heterogeneous system [10,11]. While substantial amounts of monomer are grafted, notably few of the substrate molecules actually contain a grafted chain [12]. The nonrandom structure of the graft copolymers is related to the heterogeneity of the system during graft polymerization.…”