Comparison of the enthalpy recovery and free volume of polyvinylpyrrolidone during anomalous glassy to rubbery transition.
Previous studies confirmed that along with the structural changes of the amorphous binder, that of the polyvinylpyrrolidone, the tensile strength and consequently, the dissolution behaviour of its tablets changed significantly during the storage period. Structural formation during the glassy to rubbery transition of polyvinylpyrrolidone was followed by the changes in the free volume and enthalpy recovery values of the polymer. The results suggest that the apparent structure formation of water and polymer under glassy to rubbery transition is interrelated in a dynamic and complex manner which can be tracked by the combination of enthalpy recovery studies and positron lifetime measurements. Positron lifetime measurements more sensitively react to the structural rearrangements than enthalpy recovery, thus it can be recommended as a sensitive tool for stability tests during the formulation phase of drug development.
Zelkó
Romána
R
University Pharmacy Institute of Pharmacy Administration, Semmelweis University, Hogyes E. Street 7-9, H-1092 Budapest, Hungary. zelrom@hogyes.sote.hu
Süvegh
Károly
K
D004055:Differential Thermal Analysis / Q000379:methods; D005898:Glass / Q000737:chemistry*; D044367:Phase Transition; D011205:Povidone / Q000737:chemistry*; D012408:Rubber / Q000737:chemistry*; D013816:Thermodynamics; D014867:Water / Q000032:analysis / Q000737:chemistry
D014867:Water; D012408:Rubber; D011205:Povidone