4. ConclusionThe plasticization of cellulose acetate by an environment-friendly ionic liquid plasticizer, 1-butyl-3-methylimidazoliumchloride (BMIMCl) was shown to be an efficient plasticizer of cel-lulose acetate, allowing the production of processable materials at150◦C by melt processing. Visual observations for these pressedcellulose acetate materials were transparent and homogenous.Due to the electrostatic nature of BMIMCl, it interacts intensivelywith CA molecules. XRD results clearly showed that the crystallinestructure of cellulose acetate was widely and effectively damagedwhen using ionic liquid comparatively to DEP.Two relaxation transitions were detected by DMTA with cel-lulose acetate plasticized by BMIMCl and DEP: an -relaxationtemperature which corresponds to the glass transition of the mainchain and a lower relaxation, which can depend on plasticizersflexibility and concentration.Dynamic mechanical analysis showed also that BMIMCl actedas an efficient depressor of glass transition temperature of CA withvalues close to those obtained by DEP (relaxation temperaturesmeasured by DMTA were respectively 84◦C and 95◦C for 30% ofplasticizers). For the relaxation, BMIMCl showed capability tolower this relaxation contrary to DEP.Mechanical tensile tests and rheology analyses showed a strongreduction of the interactions between cellulose acetate chains dueto the presence of the ionic liquid.