The rotational viscometer which had a uniform stress, designed by Dr. W. Philippoff was used for measuring the viscosities of 6% L-200 in PRIMOL 355 and Lekutherm x-30. Viscosities of 6% L-200 in PRIMOL 355 (polyisobutylene) was measured to check the change of material that was left in the visometer for almost two years. The result showed that the new viscosities are higher than the older results.
The main interest of this thesis is to measure the viscosity of Lekutherm x-30, epoxy resin produced from Germany. No one has ever measured the whole range of temperatures of its viscosity. The measurements were done at different temperatures and different shear stresses.
The viscosity at 29.9°C was used for a reference value in order to calculate the constants C1 and C2 from the WLF equations, and their values were used for further calculation of viscosities in a variety of temperatures. The calculated and experimental values of their viscosities were compared. The results are considerably close in their values.
The viscosities of Lekutherm x-30 were rechecked three months later. The results showed high increases in new measurements: 64% at 29.9°C, 66.19% at 31.9°C, 57.10% at 39.9°C and 30.32% at 50°C.
There are three measurements of recoil data. Modulus and relaxation times were calculated.
Lekutherm x-30 resin was used to investigate birefringence in l-2, 1-3 and 2-3 planes. For the birefringence in the 1-2 plane, the study was done at different temperatures and different shear rates. The highest temperature was 80°C and the lowest temperature was 30°C. It is difficult to measure at lower temperatures. This is due to the inability of the apparatus and the characteristics of the material being used. For low temperatures a correction angle has to be used. A new zero point is changed at 60°C by -2 degrees. The stress-optical coefficients, Cbr, were calculated and compared to the values of other investigations. At high temperatures the stress-optical coefficient is in agreement with the Kuske and Zech Value but at low temperatures their values are much higher. At low temperatures the 1:4 slit, 1:20 slit and true values of Cbr which were measured by Dr. W. Philippoff were found to be in the middle range between Kuske and Zech and my values. The 1:4 slit values of Cbr were used to calculate the Δn(1-2) at low temperatures and further these values were used to calculate the percent ratio of Δn(1-3) and Δn(2-3). The values of birefringence in the 1-2 plane were calculated from the experimental values of Cbr as a function of viscosity and shear rate.
The temperature effect of a newtonian Lekutherm x-30 resin was found to have a stress-optical coefficient dependent on shear stress and low temperature changes under 70°C. At higher temperatures above 70°C there is very little effect on the stress-optical coeficient Cbr.
The birefringence in 1-3 plane was observed by using the simple slit arrangement apparatus. The measurements were done at room temperature but the variation of temperatures that occured depended upon room temperature conditions. The values of Δ(1-3) were much smaller than Δn(1-2)values. Only one experiment could reach equilibrium. The percentage ratio between n(1-3) and n(1-2) are 2.8 and 4.5, where 2.8% ratio calculated from Cbr- true value.
The birefringence in 2-3 plane is very small, the percentage ratio between Δn(2-3) and Δn(1-2) are about one percent or less. There is a definite effect of birefringence in 2-3 plane. This conclusion was also proved in the experiment by Biss in 1974.
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