Study On Plasticization Of Cellulose Diacetate / Ionic Liquid

Cellulose diacetate (CDA) is a chemically modified regenerated cellulose. Compared with cellulose, due to the introduction of acetyl groups into the molecular chains, CDA has a certain thermoplasticity, but it still needs to be plasticized in order to be melt processed easily. Due to the poor compatibility and other problems of traditional plasticizers, the research of ionic liquids (ILs) as a kind of green plasticizer has attracted more and more attention. The research results have shown that 1-ethyl-3-methylimidazolium acetate ([EMIM]Ac) and 1-butyl-3-methylimidazolium chloride ([BMIM]Cl)’s ability to dissolve cellulose and other things is better than many other ILs. It has not been reported that [EMIM]Ac, [BMIM]Cl and the compound of [EMIM]Ac and dimethyl sulphoxide (DMSO) are excepted to have positive effect about plasticizing CDA to significantly reduce the melt processing temperature of CDA.In this paper, three kinds of plasticizing melting systems of CDA/[EMIM]Ac, CDA/[EMIM]Ac/DMSO and CDA/[BMIM]Cl were prepared, and the possible plasticization mechanism was analyzed. The structures and performances of the three kinds of plasticizing melting systems and regenerated CDA from the systems were investigated by HS-POM, FT-IR, XRD, TGA and rheometer, respectively.①The system of CDA/[EMIM]Ac was prepared, in which the mass ratio of CDA to [EMIM]Ac were 40%:60%,45%:55% and 50%:50% respectively, and the influence of the preparation conditions such as temperature and the ratio of CDA to [EMIMJAc on the structures and performances of the system were investigated;② The system of CDA/[EMIM]Ac/DMSO was prepared, in which the ratio of CDA, [EMIM]Ac and DMSO were 40%:30%:30% and 50%:25%:25%, and it was analyzed that DMSO instead of the part of [EMIM]Ac influence [EMIM]Ac on the plasticization; ③And more, the system of CDA/[BMIM]Cl was prepared, in which the ratio of CDA and [BMIM]C1 were 30%:70%,35%:65% and 40%:60%, and the influence of the ratio of CDA to [BMIMJC1 on the structures and performances of CDA/[BMIM]Cl was investigated. The systems of CDA/[BMIM]Cl and CDA/[EMIM]Ac were compared.The results prove that:All of [EMIMJAc, [BMIM]Cl and the compound of [EMIM]Ac and DMSO in three systems are effective plasticizers for CDA. Under the same conditions, the plasticization of [EMIM]Ac for CDA is superior to [BMIM]Cl, and cheaply available DMSO instead of the part of [EMIM]Ac can not only reduce costs, but also promote plasticizing effect of [EMIM]Ac. The plasticizing melting systems will be homogeneous when the systems have more than 50% of [EMIM]Ac, [BMIM]Cl or the compound of [EMIM]Ac and DMSO. CDA have not derivatization reaction in the plasticizing melting process. The structures and performances of the plasticizing melting systems mainly depend on the content of plasticizers in the systems besides preparation conditions. The melt fluidity of the systems and thermal stability of regenerated CDA increase with the increasing of the quality percentage of plasticizers. The study also found that the plasticizing melting systems have good melt processing stability, because their thermal decomposition temperature is much higher than their melt flow temperature, although their thermal decomposition temperature is lower than that of raw CDA. CDA can easily regenerate from the plasticizing melting systems in the water, and regenerated CDA still has good thermal stability.