The total birefringence of crystalline polymer for cylindrical symmetric orientation can be represented as follows; on the basis of simple additivity of the crystalline and non-crystalline contribution.
The intrinsic birefringence of uniaxially stretched polyvinyl alcohol are evaluated by simultaneous measurements of x-ray diffraction, visible dichroism and birefringence.
We transform the above equation to fallowing equation, and then, the slope and intercept on ordinate, we can evaluate the intrinsic birefringences of crystalline and non-crystalline phases, experimentally.
On the other hand, by using of Lorentz-Lorenz's equation, we determine the ratio of the intrinsic birefringence of crystalline and non-crstalline phases, and moreover substitute the ratio into the additive equation of birefringence. The symplified equation can be represented as follows; where Δ_co is KΔ_ao.
This equation shows the linear relation of Δ_t against Δ_ao, therefore we can determine the intrinsic birefringence of non-crystalline phase from the slope of the line.
Employing above two methods in our experimental results, following results are reached.
1) The average intrinsic birefringence of crystalline and non-crystalline phases are found as follows; Δ_co=51.8×10^-3 Δ_ao=43.8×10^-3
2) The principal refractive indices of crystalline and non-crystalline phases are found as follows;