chapter
46 Pages

6. Viscoelastic Properties of the Polystyrene in Concentrated Solutions and Melts

YU. G. MEDVEDEVSKIKH, O. YU. KHAVUNKO, L. I. BAZYLYAK, and G. E. ZAIKOV

Summary ............................................................................................... 130 6.1 Introduction .................................................................................. 131 6.2 Experimental Data and Starting Positions ................................... 134 6.3 Concentrated Solutions ................................................................ 135 6.4 Polystyrene’s Melt ....................................................................... 152 6.5 Characteristic Time of the Segmental Motion of Polystyrene in

Solutions and Melt ....................................................................... 161 6.6 Dynamic Properties of Polystyrene in Solutions and Melt .......... 163 Keywords .............................................................................................. 172 References ............................................................................................. 172

SUMMARY

A gradient dependence of the effective viscosity η for the concentrated solutions of the polystyrene in toluene at three concentrations ρ = 0.4×105; 0.5×105; 0.7×105 g/m3 correspondingly for the fourth fractions of the polystyrene with the average molar weights М = 5.1×104; 4.1×104; 3.3×104; 2.2×104 g/mole respectively has been experimentally investigated. For every pair of the values ρ and М a gradient dependence of the viscosity was studied at four temperatures: 25, 30, 35 and 40°С. An effective viscosity of the melts of polystyrene was studied for the same fractions, but at the temperatures 190, 200 and 210 °С. The investigations have been carried out with the use of the rotary viscosimeter “Rheotest 2.1” under the different angular velocities ω of the working cylinder rotation. An analysis of the dependencies η(ω) permitted to mark the frictional ηf and elastic ηe components of the viscosity ant to study their dependence on temperature Т, concentration ρ and on the length of a chain N. It was determined, that the relative movement of the intertwined between themselves polymeric chains into m-ball, which includes into itself the all possible effects of the gearings, makes the main endowment into the frictional component of the viscosity. The elastic component of the viscosity η

е is determined by the elastic properties of the con-

formational volume of the m-ball of polymeric chains under its shear strain. The numerical values of the characteristic time and the activation energy of the segmental movement were obtained on the basis of the experimental data. In a case of a melt the value of E and RS*∆ are approximately in two times more than the same values for the diluted and concentrated solutions of the polystyrene in toluene; this means that the dynamic properties of the polymeric chains in melt are considerably near to their values in polymeric matrix than in solutions. Carried out analysis and generalization of the obtained experimental data show that as same as for low-molecular liquids the studying of the viscosity of polymeric solutions permits sufficient adequate to estimate the characteristic time of the segmental movement accordingly to which the coefficients of polymeric chains diffusion can be calculated in solutions and melt, in other words, to determine their dynamic characteristics.