Glass temperature depression of polymer by use of mixed solvents: A colligative property

Abstract

The entropy theory of glasses is used to determine the glass temperature depression by a multicomponent low molecular weight plasticizer (diluent). The glass temperature, Tg, is calculated as a function of pressure, P, the mole fractions, mi, of the plasticizers, and the degree of polymerization p. One finds, provided there is no phase separation, that to a good approximation, the initial glass temperature depression is a function of the total mole fraction of plasticizer. Moreover, the glass temperature depression for small plasticizer molecules is found to be nearly a universal function of the plasticizer mole fraction (it depends on no other plasticizer variable), and to vary inversely as the number of flexible bonds per monomer unit of the polymer. A useful approximation is found, γdTg/dm1 = −3Tg, where m1 is the total mole fraction of diluent on a per monomer of polymer basis, and γ is the number of flexible bonds per monomer. Although these results agree with experimental data in the literature, a more definitive experimental test is needed. © 1996 John Wiley & Sons, Inc.

Diffusion in Polymer Solids and Solutions

“…Below this temperature the reduction continues but at a smaller rate. The difference between the volume observed at absolute zero temperature and the volume measured at transition temperature was considered as space, which, in the amorphous solid, is available for oscillations (Dimarzio, 1996). For the following model derivation, we assume that the state of the investigated polymer at the beginning is a glass.…”

The effect of chain density on the frictional behavior of surfaces modified with alkylsiloxanes and immersed in n-alcohols

“…44 If free-volume limited partitioning is the dominant mechanism, an increase in the extent of solvent partitioning should cause to decrease, just like the relaxation time and the glass transition temperature of an amorphous polymer decrease when the polymer is exposed to a plasticizer. [45][46][47] Thus, we expect that will increase with increasing solvent chain length or molar volume because the extent of solvent partitioning will decrease as a result of free-volume limitations. If insertion is the dominant mechanism, solvent partitioning may cause to increase because van der Waals forces between the alkyl chains and the inserted long-chain solvent molecules may increase the cohesive energy of the monolayer and restrict the mobility of the alkyl chains in the SAM.…”

A lattice-fluid model for the determination of the water/polymer interaction parameter from water uptake measurements

“…Below this temperature the reduction continues but at a smaller rate. The difference between the volume observed at absolute zero temperature and the volume measured at the transition temperature was considered the space, which, in the amorphous solid, is available for oscillations [12].…”

“…This value is also equal to the entropy of mixing . One can find a similar expression applied in the entropy theory of Gibbs and Di Marzio to predict the glass transition [11,12]. By rearranging, introducing the number of moles i n for all components i , and the volume fractions 4can be written as…”