The stress-strain curves of polyethylene terephthalate monofilaments dwawn in water at 70°C were measured at room temperature, and the effects of molecular orientation and heat-treatment on the yield phenomena, that is, the primary and secondary yielding, are discussed. In the samples with low-orientation, only the primary yielding is observed and accompanied by necking. The tensile dynamic modulus of these samples decreases with increasing strain until the yielding region. The necking is associated with the decrease of yield load with drawing. This decrease of the yield load depends upon not only the number of chains passing through the crosssection of the sample but also on the thermal effects and the state of aggregaton and orientation. Even in the hot drawing the samples fairly shrink after removal of the load, when the chains are highly strained. The primary yield strain of these samples is nearly equal to the shrinkage of the sample. Consequently (in the highly oriented samples) the extension until the primary yield point can be considered as the reverse process to the shrinkage observed after drawing. In general, the fine structures of tde drawing samples are related to the two regions, that is, “region A” and “region B”. The region A corresponds to the amorphous or low lateral order region which has taken part in the shrinking, and the region B is composed of crystallites or high lateral order region termed C and amorphous or low lateral order region A′ which have hardly taken part in the shrinking. In the highly oriented samples, the secondary yielding in the region A and the primary yielding in the region B are observed. In low oriented samples, there is only the region B which is almost the region A′ and only the primary yielding is observed. In the highly oriented samples heat-treated at constant lenghth, the shape of the load-elongation curve near the secondary yield point becomes the same as that of the untreated samples, when 8_??_11% pre-elongation is given. But the changes of the X-ray diffraction intensity and orientation of the (100) and the (010) plane with the pre-elongation until the primary yield region are very small. These facts mean that the cohesive energy density in the region A of the highly oriented samples leveled up by heat-treatmént, decreases with the pre-elongation and becomes the same order as that of the untreated samples. In the highly oriented samples heat-treated in free state, three yield points are observed when some pre-elongation between the secondary and the primary yield point is given.
The authors have shown the possibility to introduce the Newtonian theory to the polymer flow in extruder. In this paper the behaviour of polymer in extruders was observed and dealt with some theoretical methods. The tranceparent acrylic barrel was deviced to observe the behaviour in extruder, (shown in Fig.1, Fig.2 in the previous report (1)). With the aim of observation of behaviour of polymer flow, small glass balls (diameter about 0.8mm) were suspended as a fluid element, and the behaviour of the polymer was observed in the case of flat screw and the open out-let as shown in Fig.3. Fig.3 shows the feature of the moving of the element in extruder, and Fig.3′ shows the relative position of the ball in screw channel, (here after the non-dashed number of figure shows the fluid element movement in extruder and dashed number of figure shows the relative position of it in screw chnnel). The number in glass ball shows the position of the observed ball in time. Then the behaviuor of a element in the cass of closing the out-let of the flat screw was observed under the conditions of screw rotations 10r.p.m. 25r.p.m. 40r.p.m. (the interval of observation is 1/2 sec in 10r.p.m. 1/3 sec in 25r.p.m. 40r.p.m.). In case of closed out-let of screw, no substantial flow causes in the channel, but the intense transeverse flow is observed (see Fig.5, 5′, Fig.6, 6′, Fig.7, 7′). In order to discuss this flow pattern by the method of velocity vector, the authors introduce the non-dimensional number, a (in z axis), c (in x axis), defined by the viscosity and pressure gradient. At first in the extreme case of closed out-let and opened out-let by using the flat screw, the velocity vector is shown in Fig.2 (a) and Fig.4 (a). Then the authors applyed this consideration to the general metering screw having three sections, that is; feed section (flat part), compressing section (transilient part), and the end section. The feature of flow in those three sections are shown in Fig.9, 9′, Fig.11, 11′, Fig.13, 13′. The velocity vector in those three sections are shown in Fig.8, Fig.10 and Fig.12. As the results it was obtained that the transverse flow becomes more violent with the increase in back pressure gradient and in general metering screw, there is the most violent transeverse flow at the front of the comperssion part. (see Fig.15 of the preceeding report (1)).
The effects of conditions of fiber-forming processes, such as spinning, drawing and formalization, on the void content in PVA fibers are studied. The extremely small voids in fibers are measured by the diffuse scattering of X-rays at small angles. The larger voids are estimated by means of optical microscopic observation and measurement of visible ray transmittance. Wet-spinning of the aqueous solution of PVA gives fibers with higher void content and dry-spinning as well as semi-melt spinning with lower void content. The higher the rate of coagulation in wet-spinning is, the higher the void content is. Drawing of fibers increases the larger voids. Furthermore, the comparison of the void content of formalized fibers under various onditions suggestes that the initial swelling power of formalization bath affects the void content in fibers.
Silk fibroin of coagulated and dried silk gland of Bombyx mori L. shows an X-ray diagram of the so-called α form named by Shimizu. When this silk gel is stretched up to 50%, the specific diffraction of 4.5 and 7.25A spacings begin to move to the meridian and to the equator respectively. This fact seems to suggest that α-form is something like the cross-β-form, with its backbone spacing of 4.5A. On LiBr silkfilms, it has been found that the unoriented cross-β-form (intra-chain β-form) shows the same diffraction pattern and infrared spectrum as the interchain β-form. An inspection of the X-ray diffraction pattern of the silk gel revealed that the cross-β-form is not present in the gel. When the film of LiBr silk fibroin which contains the α-form is drawn with polyvinyl alcohol as a plasticizer, the amide I band at 1660cm-1 and amide II band at 1530cm-1 showed perpendicular and parallel dichroism, respectively. Therefore, the α-form is not a structure like that of the α-helix. The structure of the α-form may possibly be similar to that of polyglycine II with its hydrogen bonds projected out perpendicularly to the polypeptide chain.
The feed tension of the core filament and the drawing tension at the reel are the most important factors on the manufacture of the compound filament. In the first place, the compound filaments were manufactured under the different feed tensions and with the different sizes. The core lengths of them, then, were measured for discussion of the feed tension. In the next place, the compound filaments and the raw silk were elongated in the drenched state and after drying the strain recovery was measured for discussion of the drawing tension. The following results were obtained: 1) It was made sure that the feed tension of the core filament extends the core of the compound filament in proportion to the feed tension. 2) The upper limit of the drawing tension at the reel was experimentally obtained from the relation between the drawing tension and the recovery of the elongation. In the actual manufacturing, the drawing tension was sufficiently smaller than that. 3) It sometimes happens that the cohesion between the core filament and the cocoon fibers is broken by itself. This can be classified into two cases: the first is the case that the feed tension of the core filament is not suitable, the second is the case that the drawing tension at the reel is too large. Though the external views of the compound filament's in which break down of the cohesion causes are similar, they are not the same.
Amillan (Toyo Rayon Co.) was dyed with Orange II in the infinite dyebath at 59°C to determine the rate of dyeing. Apparent diffusion coefficient D was calculated from Hill's equation. Great change in D with concentration of dye and pH in the dyebath are attributed to the change of equilibrium uptake of dye, M∞, under these conditions of the bath. Since diffusion of acid dyes toward the interior of the fiber accompanies adsorption of dye, there is a relation between na integral diffusion coefficient _??_ and a diffusion coefficient _??_. This relation is derived under the assumption that only the unadsorbed dye is diffusible. _??_=_??_/(1-θ), where θ=M∞/S and S is saturation value. On the other hand, if chemical potential acts as a driving force for diffusion, _??_ and an actual diffusion coefficient D (c) may be related to D0 (the value of D at c=0) by _??_=(D0/θ) [-1n(1-θ)] and by D(c)=D0/(1-θ), respectively. Experimental D-θ curve was evaluated by these equations. Equations deduced from the above assumptions give some satisfaction in the relation between D and θ, although they can not be applied to every value of D. Equation, D=D0*/θ(1-θ), being in good agreement with D-θ curve, is also not satisfactory, for D should increase as θ decreases below θ=0.5. The reason why none of these equations are enough to satisfy the observed D-θ curve, is thought that charged adsorption sites interfere electrically with diffusion of dye ion.
This research has been done with the main object of improvement in wet crease resistance of the acetate fabric. Vinyl monomer i.e. methyl acrylate (MA), ethyl acrylate (EA), propyl acrylate (PA), butyl acrylate (BA), methyl methacrylate (MMA), styrene (ST), or acrylonitrile (AN) was graft-polymerized with Ce initiator onto an acetate fabric by the vapour phase method. The relation between dry or wet crease recovery and add-on or graft amount on the treated fabric has been investigated. Among those monomers only PA and BA are effective to increase dry or wet crease recovery of the acetate fabric. The mechanical properties of the BA-treated fabric i.e. crease recovery, tearing strength and stiffness were determined at different add-ons. Influence of the pretreating conditions (Ce conc., AcOH conc., temp., impregnation) and influence of the extraction of homopolymer upon those mechanical properties have been investigated. The results obtained are as follows: (1) The BA-treated fabric has the maximum dry and wet crease resistance at about 5% addon by 10_??_15% (dry) or by 15_??_20% (wet) higher crease recovery than the untreated. It has also 80% tearing strength, slightly higher stiffness, and its single fiber has an increase of tenacity, extension, and yield elongation compared with the untreated. (2) In order to obtain the highest crease recovery of the BA-treated fabric, conditions of the pretreatment should be that the Ce concentration is 0.03_??_0.1mol/l, the AcOH concentration about 10%, the temperature about 40°C and the liquid retention of the pretreated fabric is about 30%. (3) By extraction of the homopolymer with benzene from the BA-treated fabric, the dry crease recovery rises, and the wet lowers at the same add-on or grafting. (4) The reasons why PA- or BA-treatment increase the crease recovery of the acetate fabric would be that they have little swelling or dissolving power for the acetate, that the glass transition points of their polymers are relatively low, and that the treated fabric or its single fiber has rubber-like elasticity and water-repellency.