he phase behaviour and glass transition temperateal of cellulose diacetate (CDA)/poly (vinyl pyrrolidone)(PVP ) blends were extensively inveshgated by OM

DSC and DMTA. Transparency films were observed in the composition range of CDANVP= 100/0 to 50/50 (by wt.) No any phase separation was found up to the degradation temperature of blending components. A single and composition dependence Tg was obtained in all the range of blending compositions. And a synergism for mechanical properties of CDA/PVP blends was also found. The mixing enthalpy of this blending system was determined and calculated by using the calorimetry and the Hess law. Negative and composition dependent mixing enthalpy was found. All the above experimental results strongly suggest that CDA and PVP are miscible.