The calorimetric glass temperature of polystyrenes with molecular weights ranging from 3.0 × 103 to 43.7 × 106 g/mol are measured as a function of cooling rate for both bulk material and for samples freeze-dried from dilute solution. We find that Tg is depressed approximately 5 K for samples which can fully entangle and also the same amount for ultrahigh molecular weight samples which cannot achieve full entanglement. The lowest molecular weight samples show only 2 K depression on freeze-drying. Annealing eliminates the depression in Tg. The results indicate that the reduction of the glass temperature due to freeze-drying cannot be due to the reduced entanglement concentration induced by freeze-drying.
|Number of pages||5|
|State||Published - Oct 14 2003|
|Event||61st Annual Technical Conference ANTEC 2003 - Nashville, TN, United States|
Duration: May 4 2003 → May 8 2003
|Conference||61st Annual Technical Conference ANTEC 2003|
|Period||05/4/03 → 05/8/03|
- Glass transition temperature