Depression of Tg in polystyrene by freeze-drying

Paul Bernazzani; Sindee L. Simon

Depression of T_g in polystyrene by freeze-drying

Chemical Engineering

Research output: Contribution to conference › Paper

Abstract

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 T_g 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 T_g. 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.

Original language	English
Pages	1987-1991
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

Conference	61st Annual Technical Conference ANTEC 2003
Country	United States
City	Nashville, TN
Period	05/4/03 → 05/8/03

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Keywords

Entanglements
Glass transition temperature
Polystyrene

Cite this

Bernazzani, P., & Simon, S. L. (2003). Depression of T_g in polystyrene by freeze-drying. 1987-1991. Paper presented at 61st Annual Technical Conference ANTEC 2003, Nashville, TN, United States.

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abstract = "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.",

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AU - Bernazzani, Paul

AU - Simon, Sindee L.

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N2 - 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.

AB - 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.

KW - Entanglements

KW - Glass transition temperature

KW - Polystyrene

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SP - 1987

EP - 1991

Y2 - 4 May 2003 through 8 May 2003

ER -

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