Crystallization of polyethylene from solution was studied under shear strain. Making use of a rotational viscometer, a steady state flow of the solution was achieved. The crystals grown from solution under shear strain exhibited entirely the same features as those grown under no shear strain (the single crystals usually observed). Namely, the molecular orientation in the solution facilitates ctystallization but does not affect the morphology of the resultant crystals. It was found, however, that fibers were produced from 0.1% solutions and films from 1% solutions, both having grown from a few points on the rotating inner cylinder of the viscometer. These films consist of fibers which are similar to those grown from the 0.1% solutions. Electron microscopy revealed that the lamellae were piled up along the direction of the shear and aligned perpendicularly to the shearing direction. It is concluded that this sort of texture would be nothing but a quite general texture obtained when crystallization takes place under molecular orientation. It is suggested that this texture results from a bi-components crystallization where some polymer molecules crystallize first into the extended form and then the other molecules deposit into the chain folded lamellae on the substrate of the extended chain crystals. In order to confirm this assumption, measurements of D S C thermograms, specific heat, mechanical tan δ and the tensile moduli from the velocity of the propagation. of a pulse along the fibers were made for the fibers and the films grown from the solution. All the results showed a rather low crystallinity and low melting temperature of the fibers and films. In the D S C thermograms, moreover, no distinct peak was observed at the temperatures corresponding to the extended chain crystals. Also from the morphological studies no evidence has been observed on the bi-component crystallization in question. It was postulated that fibrillar structures observed did not exist when the crystallization took place but were produced by mechnical deformation of the lamellae, which occures after the precipitation of fibers and films.
It is well known that silk fibroin dissolves in the concentrated aqeous solution of neutral salt such as CaCl2 or LiBr. In this study, Some alcohols were added to the CaCl2 solution, and the dissolution of fibroin in the solution was investigated. It was found that the addition of a proper quontity of monohydric alcohol, such as CH3OH and C2H5OH improves the shlubility. C2H5OH is more effectives for the increase sf the solubility than CH3OH under equal molar addition. The addition of dihydric alcohol (C2H4(OH)2) or trihydric alcohol (C3H5(OH)3) decreases the dissolution of silk fibroin.
It is well known that silk fibroin dissolves in the concentrated aqueous solution of neutral salts. In this study, the process of the solubility was investigated from the view point of the fine structure of silk fibroin. The following results were obtained on the dissolution in the CaCl2-H2O solution. (1) The maximum solucility of silk fibroin is given under the condition CaCl2:H2O=1:8(mol). (2) The apparent activation energy obtained from the Arrhenius equation is about 27kcal/mol. (3) When silk fibroin is dissolved by CaCl2-H2O solution under the proper condition, first the amorphous part is dissolved, then the semicrystalline, and finally the crystalline region.
The loop formed by latch needles on weft-knitting machines is affected both by the yarn elongation in the knitting zone, and by the robbing of yarn at the knitting point from the loops already formed, nalmey by Robbing Back. It is, therefore, necessary to use a physical quantity in order to analyze the loop formation process. In this paper, the knitting force is chosen as the quantity, and the its measuring method is described. Some experiments using the knitting force detector showed the following results: 1) The knitting force increases in proportion to the input yarn tension, and the degree of the increase depends upon the kinds of yarn used. 2) The larger the knitting force, the shorter the length of the fabric loop. 3) It is possible to calculate the yarn tension at the knitting zont in terms of the knitting force. 4) The coefficient of yarn friction should be treated as a function of the position in the knitting zone when the values of the yarn tension are predicted according to Amonton's law.
In this paper, the effects of input yarn tension and shape of stitch cam on the loop formation process by latch needles, are analyzed by the knitting force. Experiments were performed using 5 kinds of stitch cam shown in Fig.1, changing the input yarn tension from 2 to 16g. Results obtained are as follows: 1) The length of yarn knitted into the loop depends upon the robbing back and upon the yarn elongation in the knitting zone. The yarn elongation must not be ignored even in the cam system where the cam system where the robbing back occurs. 2) The robbing back occurs in the region of loops which are held by one or two needles just passed the knitting point. The region differes depending upon the properties of the yarn used. 3) The wider the region and the larger the knitting force (the input yarn tension), the greater is the amount of yarn robbed by one needle from another. 4) The robbing back is affected by the variation of the frictional behavior of needles, which causes the vertical streaks in the knitted fabric.
The rotation and rotary inversion of textile weaves are classified into 8 groups as shown in Table 1. and it is shown that theses uccessive operation makes an Abelian group as Table 2. The conditions to be complete even-sided weave are: (1) the weave has reversion symmetry in respect to warp or/and weft way, and (2) the wecve has screw symmetry in respect to warp or/and weft way. There are 27 types of symmetry satisfying these conditions. The examples of the weaves are shown in Fig.4 using 8 harness weaves. The weaves (1) to (5) in Fig.4 and Table 3 have reversion symmetric axes along warp and weft. These are independent of the operations CY and CX, known as “the complete even-sided weave of the stkind”. The weaves (6) to (18) have reversion symmetric axes along warp or weft. These weaves transform to the equivalent weaves of the 2nd kind, by the operation CY. This is type of “the comglete even-sided weave of the 2nd kind”. The weaves satisfying the condition (2) belong to (19)-(27). These transform to the half-slided weaves along the warp-way of initial weaves, by the operation CY, knowd as “the complete even-sided weave of 3rd kind”.
There are two equations to evaluate the rate of dyeing from a finite dyebath, one of which is a exponential form A=A∞(1-e-Kt), where A is the percentage of dye adsorbed at a time t, A∞ the equilibrium exhaution and K a velocity constant. In this paper, this equation is expanded to the case of an infinite dyebath, and a simple equation to obtain the diffusion coefficient within a fibre is derived. The equation is: -ln(1-Ct/C∞)=5.85Dt/r2+0.346 where Ct is the amount of dye adsorbed at t, C∞ the amount at the equilibrium, D the diffusion coefficient of dye and r the radius of the fibre. This logarithmic equation agrees with that of the Hill's and also experimental results, provided Ct/C∞>0.5. Applying this equation, C∞ can be calculated from adsorption data at some arbitrary short times with an accuracy which is sufficient for most purposes.
The dyeing behavior of partially chlorinated polyolefine fibres with a thiazine type cationic dye and mono azo disperse dyes were investigated. As the result it is obtained that each dye uptake is increased with increase of chlorination degree of the fibre. It is assumed that the dyeing behavior of cationic dye is mainly due to the ion-dipole interaction between positively charged cationic dye and C-Cl group in the partially chlorinated fibre, but the dipole effect of the fibre is weaker than that of the fluorinated fibre. It was found that the rate of penetration of cationic dye into the outer surface of the partially chlorinated fibre was decreased by increasing the chlorination degree of the fibre. The reason for this result is assumed that the cationic concentration of internal solution in the fibre should be increased with assistance of the small inorganic cations which are located on the negatively charged chlorine sites of the fibre. It may be expected, therefore, that the diffusion of the dye is retarded by the repulsive action of the inorganic cations. The dyeing behavior of disperse dye may be principally due to the dipole-dipole interaction between a functional group (e. g. amines) of dye and C-Cl group in the partially chlorinated fibre.