EFFECT OF NUMBER AND MOLECULAR WEIGHT OF THE GRAFTED BRANCHES ON SOME PROPERTIES OF GRAFTED PAPERS

Abstract

Acryronitrile (AN) or methyl methacrylate (MMA) was graft copolymerized onto slightly methacrylated paper and the various kinds of papers grafted by the high and low molecular weight branches were prepared. The effects of the molecular weight and the number of the grafted branches on the strength, the acid and alkali resistance and the hygroscopicity of the paper were examined.The following results were obtained. 1) The wet or dry strength of the paper grafted by the high molecular weight branches with the smaller number of the branches was higher than the corresponding strength of the paper grafted by the low molecular weight branches with the larger number of the branches, in comparing the same degree of grafting. The wet strength of the AN-grafted paper was much higher than those of the original and the MMA-grafted ones. 2) The acid and alkali resistances of the paper increased on grafting, but the hygroscopicity decreased. The acid and alkali resistances of the paper with the high molecular weight branches and small number of branches were superior to those of the paper with the low molecular weight branches at the same degree of grafting. The hygroscopicity of the paper with the low molecular weight branches was higher than that of the paper with the high molecular weight branches at the same degree of grafting. These results suggest that the high molecular weight branches (the small number branches) do not so change the fine structure of the cellulose fibers as the low molecular weight branches (the large number branches) do.It is concluded that the properties of the grafted paper depend on the difference in the number and the molecular weight of the grafted branches even if at the same degree of grafting. This must be kept in mind in investigating the properties of any other grafted paper.