Rheological properties of elastomers based on cellulose fibers

Abstract

SynopsisElastomers, based on cellulose fibers, were synthesized by grafting ethyl acrylate onto fibers preirradiated by a high-energy electron beam. The rheological properties and fine structure of the elastomers were investigated in order to determine factors in development of rubber-like elastomeric behavior. Mechanical properties of the elastomers depended on (1) degree of polymerization of irradiated cellulose molecules, (2) extent of grafting, and (3) experimental methods of evaluation, particularly in varying environmental conditions, for example, in making measurements in air, water, or ethyl acetate. Glass transition temperatures of the elastomers were dependent on the environmental conditions of evaluation; stiffnesses of the elastomers levelled off a t about 0°C; and in all environments, a rubber-like plateau was observed. Poly(ethy1 acrylate) separated from the elastomers was not soluble in acetone. The mean molecular weight of the separated poly(ethy1 acrylate) of the elastomer was determined in ethyl acetate by the equilibrium swelling method. Electron microphotographs of cross sections of the elastomers, which exhibited rubber-like behavior, indicated that the fibrillar structure of the irradiated cellulose fibers formed a uniform network and that poly(ethy1 acrylate) was uniformly distributed among the fibrils.It was concluded that crosslinks existed in the elastomers.

Graft Copolymerization of 4-Vinylpyridine Onto Modified Cellulosic Fibers. the Ceric Ion Concentration Effect

“…Hence, there will be a tendency for the reacting molecules of monomer and initiator to approach the crystalline regions better than when the reaction is performed on unmodified cellulose. 24 show the same C, values. Fig.…”

Copolymerization of cellulose with methacrylic acid by the xanthate process

“…Methods described in the literature for the determination of the molecular weight of graft copolymers usually rely on first hydrolyzing away the cellulose with a suitable agent. Nakamura et al (1970) used 72% sulfuric acid and Gulina et al (1965) employed a mixture of acetic acid, acetic anhydride, and sulfuric acid for that purpose. While both methods were successfully applied by Hornof et al (1975Hornof et al ( , 1977 for the analysis of other graft copolymers, they proved to be inadequate for the copolymers of methacrylic acid as the precipitate formed after the treatment could not be dissolved in any known solvent.…”

Electron beam radiation graft modification of preformed polymer architecture

“…By grafting ethyl acrylate onto rayon fibers the elasticity of the fibers was improved; this means that after stretching the grafted fibers recovered their original state whereas the ungrafted fibers did not [22]. The tensile strength, however, decreased owing to cellulose chain-scission caused by the EB treatment.…”