VAPOUR PHASE GRAFTING OF VINYL MONOMERS ONTO RAYON BY CERIUM INITIATOR

Abstract

Based on our experience of the vapour phase acetylation of cellulose, the vapour phase grafting of methyl acrylate, ethyl acrylate, methyl methacrylate and acrylonitrile onto viscose rayon pretreated by cerium ammonium nitrate solution were studied and the influence of the initiator and nitric acid concentration in the pretreating solution, atmospheric pressure in the reaction vessel, and reaction temperature upon the grafting were investigated. Some mechanical properties of the grafted rayon were measured. The results obtained are as follows:(1) For e. g. AN grafting, about 150% retention of the pretreating solution by the rayon is most favourable.(2) MA or EA grafting is the first order reaction, MMA the sigmoid, and AN the fibrous reaction controlled by diffusion.(3) Ultimate graft amount of each monomer shows the maximum in relation to the initiator and nitric acid concentration in the pretreating solution.(4) Ultimate graft efficiency of AN or MMA is about 90%, but that of MA or EA decreases linearly with the initiator concentration.(5) Ultimate graft amount of each monomer decreases with the increase of carbonyl content of the rayon when the initiator concentration is increased.(6) DP of MMA graft polymer increases nearly parallel to the increase in the amount of graft with reaction time. The minimum of DP curve of ultimate graft polymer with respect to the initiator or nitric acid concentration, corresponds nearly to the maximum of the related graft amount curve.(7) The apparent activation energies obtained are MA6.7, EA8.5, MMA8.2, and AN 10.1 kcal/mol.(8) Atmosphere in the reaction vessel controlls the monomer vapour diffusion by the pressure variation and retards the grafting by oxygen in air. If air is replaced by nitrogen, graft amount of MA or EA increases several folds, but that of MMA or AN does not.(9) The breaking load of the grafted rayon is almost constant, the extension increases slightly, the initial modulus of MA or EA grafted decreases slightly, that of MMA or AN grafted increases slightly with graft amount.