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  • Title: Assessment of polymer-polymer interactions in blends of HPMC and film forming polymers by modulated temperature differential scanning calorimetry.
    Author: Nyamweya N, Hoag SW.
    Journal: Pharm Res; 2000 May; 17(5):625-31. PubMed ID: 10888317.
    Abstract:
    PURPOSE: To assess the miscibility and phase behavior of binary blends of hydroxypropylmethyl cellulose (HPMC) with hydroxypropyl cellulose (HPC), methylcellulose (MC), and polyvinylpyrrolidone (PVP). METHODS: Polymer-polymer miscibility was assessed by measurement of the glass transition temperature (Tg) and the width of the glass transition temperature (W-Tg), using modulated temperature differential scanning calorimetry (MTDSC). RESULTS: HPMC K4M/PVP and HPMC E5/MC blends were miscible as evidenced by a single, composition dependent, Tg throughout the entire composition range. HPMC/HPC blends were immiscible at all compositions. For the miscible blends, the variation in Tg with blend composition was compared to the values predicted by the Fox and Couchman-Karasz equations. At intermediate blend compositions, HPMC K4M/PVP blends exhibited negative deviations from ideal behavior. The Tg of the HPMC E5/MC blends was found to follow the Fox equation. The W-Tg measurements of the miscible blends gave evidence of phase separation at certain compositions. CONCLUSIONS: MTDSC was shown to be a useful technique in characterizing the interactions between some commonly used pharmaceutical polymers.
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