In the melt spinning of polyether-ether-ketone (poly(oxy-1, 4 phenyleneoxy-1, 4 phenylenecarbonyl-1, 4 phenylene)) (PEEK), measurements of the spinline tension and of the changes in the temperature, diameter and birefringence of the filament along the spinline were performed. The cooling, deformation and structure development behaviors of the PEEK spinline were analysed by using the results of these measurements. For the analysis of the cooling behavior, the effect of heat radiation was considered together with the effect of heat transfer since PEEK has a relatively high processing temperature. The heat radiation includes the radiation from the surface of the filament to the air and the radiation from the surface of the heated spinning head to the filament. The numerical analysis revealed that the effect of heat radiation is predominant near the spinneret, and led to an empirical formula of Nu=0.16Re0.520 for the heat transfer component. An apparent elongational viscosity derived from the results of the spinline measurements was more than ten times larger than the elongational viscosities estimated from reported shear viscosities assuming the Newtonian fluid. The temperature dependence of the apparent elongational viscosity also was higher than those of the shear viscosities. This tendency was more significant when the take-up velocity was low and the spinline was cooled slowly, or when the take-up velocity and eventually the spinline stress were high. Consequently, the deformation of the filament becomes rather steeper at high take-up velocities, and the cohesive fracture of the spinline tends to occur. The birefringence measured for the filaments in the spinline started to increase with an increase in the spinline stress. At the region where the deformation was almost finished, the birefringence increased more rapidly than the spinline stress, and then saturated. The large apparent viscosity and the steep increase in the birefringence appeared to be caused by the crystallization of the spinline.
Commercial nylon 66 fibers were dipped in a chloroform solution of t-butyl perbenzoate (TBP) at 60_??_65 °C under nitrogen for a predetermined period and then crosslinked at 150°C for 2h. When the time of dipping in a 30% TBP solution exceeded 2h, the crosslinked fibers became partially insoluble in hot formic acid. Density and gel content of crosslinked fibers increased and then decreased with the increase in time of dipping, which corresponded to the increase and decrease in TBP content in dipped fibers measured by DTA. X-Ray analysis showed that degree of crystallinity of crosslinked fibers decreased with the increase in time of dipping due to the cleavage of smaller crystallites. Young's modulus of crosslinked fibers increased with prolonged time of dipping up to 10 days in spite of the decreases in density and gel content, suggesting that the effective crosslinking occurred as a result of the penetration of TBP into the more inner part of fibers.
To clarify the swelling behavior of a cellulose-partially hydrolyzed polyacrylamide graft copolymer as a super water-absorbent, the effects of swelling conditions such as the concentration of neutral salt and pH value on the swelling of the graft copolymer were studied. The absorbency of the copolymer, the porous structure of the hydrogel of the copolymer, and the dynamic viscoelasticity of the hydrogel were examined. The absorbency was decreased steeply by the addition of sodium chloride. It depended remarkably on the solution pH and had a maximum value at about pH 7. Examination using the solute exclusion technique revealed that the distribution of pore width in the graft copolymer swollen in water differed from those in aqueous sodium chloride solutions and in an acidic or alkaline solution. When the concentration of sodium chloride increased or the pH was reduced or increased from pH 7, the cumulative pore volume up to 560 Å in pore width decreased. Their relative value, however, increased accompanying the increase in the values of dynamic viscoelasticity of the hydrogel.
To make clear the action of organic solvent in solvent-assisted dyeing process, the surface tension of an aqueous solution of benzyl alcohol and acid dye (C. I. Acid Orange 7 or C. I. Acid Yellow 36) mixture was measured as a function of the total molarity (m) and the composition (X2) of the mixture at 298.15 K under atmospheric pressure. By applying Motomura's thermodynamic equations to the experimental results, the total surface densities (_??_H) and the composition (XH2) of the mixed adsorbed-film were evaluated numerically. The results indicated that dye in the mixed adsorbed-film is richer than in the mixed bulk solution, when the mixed dye is more surface active than benzyl alcohol. Accordingly, these results showed that, contrary to Giles's description (the presence of the organic solvent depresses the concentration of dye at the interface with air.), the presence of benzyl alcohol increases the concentration of dye at the interface with air, and most probably with wool or nylon fiber. It is thought that this effect occurred by benzyl alcohol is one of the prime factors which accelerate dye-diffusion into fiber.
The effect of dye on molecular motions of poly (ethlene terephthalate) (PET) was investigated by dynamic viscoelastic measurement of PET films dyed with C. I. Disperse Violet 1 (Violet 1) and C. I. Disperse Orange 3 (Orange 3). Both α and β loss modulus peaks of dyed films shifted to lower temperature side with increase of dye concentration. The relaxation intensity of β dispersion decreased with increase of dye concentration. As the dye concentration in the films increased, the number of segments per cross section derived from the relaxation intensiy of β dispersion decreased, and then became constant at a certain dye concentration which was defined as the critical dye concentration. The critical dye concentrations for Violet 1 and Orange 3 were equal, had a same value of 2.0×10-5 mol/g•film. For the basic dye, Crystal Violet (CV), the critical dye concentration was 0.6×10-5 mol/g•film. As the dye concentration in PET films increased, the melting points of films were depressed, Interaction parameter between polymer and dye, X1, was obtained using Flory's equation which indicated the melting point depression of mixed polymer systems. The values of X1 of CV, Violet 1 and Orange 3 were positive, slightly positive and approximately zero respectively. These results suggest that CV molecules aggregate at low dye concentration because of weak interaction between CV and PET, and that Violet 1 and Orange 3 are in the state of molecular dispersion in PET even at high concentrations.
A pressure sensor method was developed in order to measure spontaneous water uptake perpendicular to fabric plane. Water absorption was detected by a pressure sensor which was placed at the bottom of a water reservoir. Using this apparatus, water absorption of some types of woven fabrics was measured. Relation between water absorption, M (t) (g/cm2) and square root of time elapsed, t (s) is well fitted by first order regression equation. From this relation, water absorption rate constant k_??_ (g/cm2√s) can be obtained and water absorptivity can be evaluated using k_??_ and Mmax (g/cm2), maximum water absorption. Based on the measurement of mean pore diameter by bubble point method, it is shown that water absorption perpendicular to fabric plane does not follow Washburn's law. Water absorption phenomena is explained well by non-linear diffusion equation and the fact that M (t) is regressed well by √t is also explained by this model. If open pore structure between fibers is modelled by lattice space and water flow by capillary action is considered to be random walk within this network, it is understandable that water absorption perpendicular to fabric plane can be explained by diffusion model. The transport mechanism is different between in-plane capillary water flow reported in a previous paper and water absorption perpendicular to fabric plane reported here. Therefore, it is considered that water absorptivity has to be estimated for each direction, i.e. parallel and perpendicular to fabric, respectively.
A comparative study was carried out on the reaction products of phosphoryl chloride and ammonia (phosphoryl amides) in a conventional solvent, ethyl ether, and in methanol saturated with ammonia. In ethyl ether, amide-substituted products were practically insoluble in the solvent, thus the reaction mixture became slurry in the course of the reaction and the complete substitution of amide for chlorine was difficult, while in the ammonia-saturated solution, the reaction products were almost soluble in the solvent and more than 90% of reaction products was phosphoryl triamide. While phosphoryl triamide and ammonium chloride (a by-product of the reaction) have low solubility in both solvents, methanol and liquid ammonia, the ammonia-saturated methanol was a good solvent for both phosphoryl triamide and ammonium chloride. Although the reaction of methanol with phosphoryl chloride proceeded vigorously even at lower temperatures, only a very small amount of methoxy-substituted products were detected in the reaction mixture by use of the ammonia-saturated solution. Therefore, the ammonia-satu-rated methanol was very suitable for the preparation of phosphoryl triamide for shrink-proof finish of rayon and silk.
The crystallization behavior of syndiotactic polypropylene with high stereoregularity was evaluated by density measurement, wide angle X-ray scattering (WAXS) and small angle X-ray scattering (SAXS). The peaks of scattering patterns could be observed by WAXS immediately after the crystallization started, but not by SAXS. The peaks of scattering patterns could be only observed by SAXS when the crystallinity calculated from the density was above 25%.