In order to clarify polymer conformations prior to crystallization, crystallization behavior of poly (ethylene terephthalate) (PET) from a quenched, amorphous state has been examined. The crystallinity of the samples annealed in the low temperature range 130°C to 180°C was nearly constant at ca. 40%, supporting a model similar to Yeh's folded chain fringed micellar grain model but without local orientation of the segments. IR measurements (CH2 rocking and CO stretching) showed that the content of trans-CH2-CH2-bond was as low as ca. 10% in the original sample, indicating the existence of quite local bends in the PET chains in the amorphous state. Tg, as determined by dilatometery as a function of the annealing temperature, showed an abrupt drop at 170°C, indicating the destruction of the “fringed micellar network”. Weight loss vs time curves during treating the samples by monoethylamine also reflected the destruction of the “network” and the formation of new lamellar crystals at higher temperatures than 170°C. Finally, DSC measurements of samples before and after treating by the amine, suggested that the small peak appeared at ca. 160°C for the sample annealed at low temperatures (120°C_??_160°C) may be due to the melting of the crystals formed in the grain boundary proposed by Yeh.
In the previous papers was discussed the twisting mechanism of air-jet twister, in which high pressure air tangentially ejected to the inner surface of the cell from the small holes forms a vortex. Furthermore the new alternate twisting method using air-jet false twister was shown. In this paper the twist distributions of alternately twisted yam are discussed on the basis of the law of superposition: the twist of the indicial response at the supply of air is superposed on the twist at the stop of the air supply. The results obtained are as follows: 1) From the law of superposition, the alternate twists can be expressed for single twist (1) and for ply twist (2) where t: time f1 (t): twist of indicial response when air was supplied to the twister f2 (t): twist of indicial response when air supply was stopped T: time of one cycle τ: time to supply air in one cycle L: time of phase lag α: constant 2) It is found that the alternate twist varies in accordance with the ON-OFF ratio of the supplied air, and the twist distributions calculated by equation (1) and (2) agree with those of experimental values. 3) The twist number of the plied yarn decreases in case of air supplied to two twisters in the form of phase lag, and this is also recognized by the calculation. 4) The alternate twist can be calculated by the superposition of the twists of the indicial response.
The temperature dependence of the impact fracture energy of composites reinforced with random-planar orientation of short fibers was studied theoretically and experimentally. The theoretical impact fracture energy of composites could be given by the sum of the fracture energy of matrix and fibers, and the energy to pull out fibers on crack surface, taking the temperature dependence of the critical fiber length and the breaking probability of fiber into consideration. The impact fracture energy was studied experimentally for epoxy resin and unsaturated polyester resin reinforced with random-planar orientation of short glass fibers. The theoretical values of impact fracture energy were in good agreement with the experimental ones. It was found for both composites that at room temperature, the impact fracture energy of fibers in a composite, while at higher temperature, the energy to pull out fibers, mainly contributes to the fracture energy of the composite.
Polyester copolymers were prepared by polycondensation of pairs of the following diacids with ethylene glycol: Terephthalic acid, sebacic acid, 1, 2-diphenoxyethane-p, p′-dicarboxylic acid (B), 1, 2-di (o-methylphenoxy) ethane-p, p′-dicarboxylic acid (M), and 1, 2-di (o-methoxyphenoxy) ethane-p, p′-dicarboxylic acid (V). The copolymers obtained and their hot-pressed films were subjected to following measurements; melting point, crystal spacing, density, crystallinity by X-ray method, glass-transition (Tg) and cold crystallization temperatures (Tcc) by DTA method, and dynamic viscoelasticity. From their melting points and crystal spacings, B-M, M-B and V-B copolymers are supposed to be isomorphous. Effects of isomorphism are observed in the following phenomena; smaller decrease in density and crystallinity, smaller increase in (Tcc-Tg), smaller decrease in half width and peak temperature of mechanical primary dispersion, smaller increase in dynamic modulus at 50°C, and smaller decrease in dynamic modulus at 120°C. Some discussion was made on these results.
The following equations have been obtained by the author from the studies on the depths of intaglio rollets used in roller printing of textile fabrics: WE/WT=85/15 VE=k(WT)2×107 where WE; width of rollet trough in 10-2mm, WT; width of rollet ridge in 10-2mm, VE; volume of rollet trough in mm3/m2k; constant. All the depth values reported so far can be explained by changing k value in the latter equation. It is concluded that, from the changes in k value, the cross-section of rollet trough is transformed to a shape with a greater degree of curve in, and, contrary to what is believed generally, there is a distinct correlation between the rollet number and the depth of rollet trough.
Recently various forms of squeegees such as plate squeegee and rod squeegee have been used in screen printing. However, since the function of these squeegees is not yet clearly understood, the operational conditions for the squeegees are now being chosen by the rule of trial and error. In order to know the function of squeegee profile, the experiment made by Dowds on plate squeegee was followed more quantitatively by including rod squeegee by Taguchi. Through analysis of their data, we found that the amount of printing paste applied to fabric in screen printing is controlled by profile of squeegee as given by the following equation: where: VP; amount of printing paste applied in g/m2, A; squeegee angle in degree, B; base length of squeegee in mm, C; constant. Values of VP given by the above equation agree very well with those obtained from empirical consideration on the shape of squeegee section.