Determination of the Molecular Weight of Linear Polymers From Viscosity Measurements Carried out in the Solvent Mixtures

Year 1989, Volume: 35 , 0 - 0, 01.01.1989

E. Pulat

https://doi.org/10.1501/Commub_0000000339

https://izlik.org/JA99CA43RW

Abstract

In this work polyvinyl acetate prepared by B. D. H Laboratory »Chemicals Di- vision has been used. The intirinsic viscosities have been determined in acetone-benzene mixtures of various percentâges. By using these intrinsic viscosity values the viscosity average molecular weights of the same polyvinyl acetate sample have been calculated from this relationship:
[?]] = K' M»' (1)
In this equation the values of K and a' are calculated from the following equations:
K' = — Ki (1—fi)3 + K2 (1—fi)3 (2)
a' = «ı fi + a2 ( 1—fı) (3)
Where fi stands for the volüme fraction of one solvent in the solution. Kn aı and K2, a2 are constants for a given polymer-solvent system and temperature.
The values of Kn aı and K2, a2 are given in the literatures [1, 2 ] for polyvinyl ace- tate-benzene and polyvinyl acetate-acetone systems.
The values of the molecular weight abtained by this method are satisfactorily good within experimental errors. The benzene-acetone mixture is better than püre ben¬zene and acetone as solvent for the polyvinyl acetate. Especially the solution containing 20-40 % benzene is the most effective solvent for this polymer. Here polar and nonpolar parts of the polymer are respectively affected by acetone and benzene.

Keywords

Determination , Molecular , Linear

References

• Communications Faculty of Sciences University of Ankara Series B Chemistry and Chemical Engineering