Melt spinning experiments of E glass have been carried out under wide range of spinning temperatures, out-put velocities and take-up velocities. Diameter of spinning fiber, fiber temperature along the spinline and tensile force were obtained as function of distance from the spinneret. Distributions of the diameter were almost independent of spinning temperature. The effect of the variation of out-put velocity on temperature distributions along the spinline was noteworthy. The tensile force was strongly affected by the change of spinning temperature and take-up velocity, but was independent of out-put velocity. The elongational viscosity of the molten glass was monotonously increased with increasing the distance from the spinneret along the spinline. For lower take-up velocity, the logarithm of the elongational viscosity was proportional to the inverse of absolute temperature and was independent of either out-put velocity or spinning temperature. For higher take-up velocity, however, the above proportionality does not hold. The elongational flow of the molten glass during spinning was found to be non-Newtonian flow. The non-Newtonian flow was discussed in terms of the internal structure of glass.

View full abstract

Stress distributions in and about a slot engraved on one side of the parallel slit walls were determined by the birefringence method for the two dimensional flow of polyethylene and polystyrene melts. By the application of shear difference integration method to the deviatoric stress analysis, it was concluded that the magnitude of the hole pressure error was proportional to the stress asymmetry with respect to the slot center plane normal to the direction of shear. To clarify the elastic effect on the stress condition, birefringences of jelly (gelatin concentration 5 or 10 wt%) solidified in the same duct were measured under constant static loads applied through a plunger to the same direction of flow. Judging from a series of experimental results of Arai et al. on the elastic gel birefringence method, principal stress direction and intensity thus for the jelly observed were regarded as nearly identical with those of Newtonian liquid flowing at low Reynolds number. The comparison of the results of jelly with those of polymer melts gave a conclusion that, as opposed to the distribution of principal stress intensity for the Newtonian flow which was expected to be symmetric with respect to the slot center plane, the distribution for the viscoelastic flow was markedly asymmetric in a sharp contrast to its nearly symmetrical streamlines. These facts suggested that the hole pressure error could be attributed to be the asymmetrical distribution of stresses which could hardly be caused by the directional change of streamline itself. Finally, present conclusions were compared with the presupposition on simple shear adopted in the theory of Higashitani and Pritchard in 1972, and the validity of the present method was discussed for the calculation of the hole pressure error.

View full abstract

The effect of sodium lignosulfonate (NaLS) on the flow properties of cement paste was studied using a coaxial cylinder rheometer. The apparent viscosity, η_a, shows a rapid increase with time, due to the hydration of C₃A(3CaO·Al₂O₃) and C₄AF(4CaO·Al₂O₃·Fe₂O₃). At the initial stage of hydration, the fluidity of paste decreases at first with NaLS concentration and shows a minimum at 0.1%. The further additions of NaLS lead to an increase in the fluidity. When the hydration proceeds, NaLS does not cause a significant change of fluidity. It is considered that NaLS has a strong effect on the initial hydration process.

View full abstract

Stress relaxation under large deformation and transient viscoelastic properties of carbon black-linseed oil suspensions were investigated using a cone and plate type rheometer.
The equilibrium moduli in the long time region were observed in stress relaxation curves even under a large shear strain such as 6.0 shear unit, and these values exhibited a remarkable strain dependence. These phenomena may be attributed to the formation of close structural networks of carbon black particles in linseed oil.
Shear stress development after sudden initiation of steady shear flow showed a overshoot and approached a steady-state value. This transient phenomenon seems to be caused by the break down of the structure of dispersed particles by shearing stress. Under steady flow conditions, the structural networks were destroyed completely. Therefore, the equilibrium values could not be observed in the stress relaxation curves after cessation of the steady flow.

View full abstract

Wavelength dependence of the photodegradation of nylon 6 was investigated by using spectrally dispersed light in the wavelength range of 300 and 550nm. On irradiation with light above 300nm, the dynamic modulus E′ was increased at each wavelength between 300 and 500nm. From measurement of [η] and X-ray diffraction, it was found that the increase in E′ by irradiation was a result of crystallization accompanied by scission reaction between amide groups. Change in E′ as a function of irradiation time was linear and was expressed by the equation, E′(t)=E₀′+kt, where E′(t) is the dynamic modulus at time t, E₀′ is that at t=0, and k is the rate constant. In the tanδ versus temperature curve of nylon 6 irradiated at the wavelength above 300nm, the α-relaxation (85°C) was broadened and the intensity of the β-relaxation at -45°C was lowered. However, behavior of the γ-relaxation (-100°C) was not changed.

View full abstract