In this paper, the theories of the proportional limit and yielding based on the small deformation mechanism in glassy state, discussed in the earlier issue, are formulated and compared with the experimental results obtained in part I. A theory of proportional limit is formulated in connection with the following two cases. First, it is assumed that the proportional limit is observed on a load-elongation curve when the average rotational angle or average strain of the segments reaches a critical value. Second, it is assumed that the secondary bond supporting the segment, in which the strain or rotational angle has reached a critical value, begins to break, the proportional limit is observed when the proportion of the broken segments reaches a certain value. Next, it is found that the following equations are applicable to the explanation of the yield point in the small strain region. where ezp is the strain of proportional limit; eszy the yield strain in the small strain region; σys the yield stress in this region; k a constant, s the average inter-molecular slip at the yield point, and E Y'oungs modulus. To the yield stress in the small strain region, another theoretical equation is introduced. This treatment is based on the following assumptions: 1) All the segments in which strain has become larger than a critical value, eay have an equal tension, pay. 2) The yield point is observed, when the proportion of these segments reaches a certain value. Finally, the yield stress in the large strain region (the primary yield stress of high orientation samples) is approximately expressed by the equation given below. where c0 is a constant, θ the angle between the fiber axis and segmental axis, and py the average yield strength of molecular chains and is experimentally given by a exponential function of orientation factor. In addition, the experimental relationship between the logarithmic primary yield stress and the Young's modulus is linear, and the elastic limit and the yield point in glassy state fairly depend upon the orientation of amorphous molecular chains.
The aging effect on the fine structure has been investigated of the undrawn PET fiber melt spun by means of differential thermal analysis (DTA), dilatometry, density, birefringence, load-extension and dynamic mechanical measurements. The results obtained on the aged sample are as follows: 1. An endothermic peak in DTA apears at a lower temperature than T_??_, which suggests that a destruction of the fine structure originated by aging is producted at the very temperature. 2. An abrupt extraordinary voluminal expansion in dilatometry is observed in response to the temperature where the endothermic peak in DTA curve appears. It may be related to the volumeric relaxation which occurs in aging. 3. Necking stress increases with aging time and an yield point appears in a further drawing after the necking. It suggests the formation of stronger intermolecular bonds by aging. 4. A very small increase is observed in density. The results (1), (2) and (3) suggest that this small increase in density is due to the increase in the density of amorphous region but not due to the crystallization. 5. The location of β absorption maximum of mechanical tan δ shifts to the side of a lower temperature, which means that the local mode motion of COO groups is made easier by ageing. Birefringence decreases as the ageing time increases. From these results the effect of aging on the fine structure of PET is considered to be explained as follows: The volumeric relaxation is produced in an amorphous region, accompanying the increase in the intermolecular bonding energy. On the other hand, the decrease in restraint of a molecular chain accompanied by the volumeric relaxation gives a favorable effect on the local mode motion and shifts the β absorption maximum of tan δ.
Graft polymerization of MMA onto cotton fiber and cloth have been carried out in emulsion and aqueous solution in the absence of an initiator. (1) Relationships among the yield of total polymer, weight increase of cotton fiber, yield of graft polymer and graft efficiency, and kind and concentration of emulsifiers have been studied. It has been found that those relationships vary with the changes of concentration and the kind of emulsifier, and that the presence of emulsifiers has a good effect on grafting. Generally the use of non-ionic surfactants is more effective than that of anionic ones. Addition of anionic surfactant to the non-ionic one reduces the effectiveness. (2) Relationship between the weight increase of cotton (fiber and cloth) and the conditions of polymerization has been studied. The polymerizations have been performed in aqueous solution and emulsion (Neugen YX-500 as emulsifier) in a sealed tube. The weight increase of cotton fiber and cloth graft-polymerized in emulsion is generally greater than that in aqueous solution. Particularlly, the weight increase is affected by the concentration of emulsifier. (3) Physical properties of grafted cotton fiber and cloth have been also observed the properties vary with the increase of weight. It has been found that, when the polymerization conditions (polymerization medium, quantity of cotton, and quantity and kind of emulsifier) are varied, some of properties of grafted cotton fiber become different.
The vapour pressures, latent heat of sublimation and associated entropy changes of eight anthraquinone derivatives, six diphenylamine derivatives and seven azobenzene derivatives have been measured by the Knudsen's effusion method. The heat of sublimation and associated entropy changes for two main derivatives of anthraqinone and diphenylamine is discussed in terms of molecular structure, based on the assumptions of additive property of energy and exsistence of hydrogen bond, and the following results have been obtained. 1. The heat of sublimation for 1:4-diamino- and 1-amino-4-hydroxy-anthra-quinones are 2 and 1.2 Kcal/mol greater than that of anthraquinone respectively. 2. The heat of sublimation of 1- and 2-aminoanthraquinones is 3.8 and 11.3 Kcal/mol greater than that of anthraquinone respectively, and an increase of these values is chiefly due to the intermolecular hydrogen bonds. 3. The heat of sublimation of 2-nitro- 4-nitro- and 2:4-dinitro-diphenyl amines is 2.2 and 7.8 Kcal/mol greater than that of diphenylamine respectively. and an increase of these values is due to the increase in polarity. 4. The heat of sublimation for 4′-amino- and 4′ hydroxy-2:4-dinitrodiphenyl amine is 1.8 and 5.3 Kcal/mol greater than that of 2:4-dinitrodiphenylamine respectively, and an increase of these values is chiefly due to the intermolecular hydrogen bond.
In order to know dyeing properties and the mechanism of disperse dyes in three different solvents, measurements of the solubilities of disperse dyes in octane, n-buthylalcohol, and water and pertition coefficients from these solutions, have been made at the temperatures of 80°, 90° and 100°C. Affinities, heat of dyeing and heat of solution have been derived. From these values, the absolute heat of association of the dyes with the PET-substrate (ΔHabs) has been estimated, and the following results have been obtained. 1. The greater the values of solubility, the smaller the values of affinity irrescective of solvents. 2. The higher the values of inorganicity/organicity of dyes, the greater the solubilities of dyes in water, but the smaller in the case of octane. 3. It is suggested from the values of ΔHabs (23_??_35 Kcal/mol) that dispersion force between aromatic nucleus of PET molecule and aromatic or anthraquinone nucleus of dye molecule makes a considerable part of contribution to the dye-PET interaction, and additionally, dipole-dipole interaction or hydrogen bond makes a contribution to interaction.
The tensile tests of Polypropylene, Nylon 6 and polyester Tetoron fibers have been carried out with tensile speed varying from 3.3×10-3cm/sec to 1.6×102cm/sec, and the shape of fibers at the point of rupture has been investigated with microphotographs. The following results have been obtained: (1) All kinds of fibers are broken down at high tensile speed found to have a tip of the nailhead shape at the point of rupture, the shape of ruptare can easily be distinguished from rupture due to ductility or brittleness. This kind of rupture is named melting type rupture. (2) With the increase of tensile speed, the type of rupture found at the breaking point of the fibers also changes in the order of ductile, brittle and melted rupture. (3) The lowest tensile speed at which melting type rupture appears is 3.3×10-3cm/sec for polypropylene fibers, 1.6cm/sec for Nylon 6 fibers, and 1.6×102cm/sec for PET fibers. This shows that the lower the melting point of fiber the lower the impact speed at which melting type rupture appears will be.
The impact test of Polypropyhene, Nylon 6 and polyester Tetoron fibers have been carried out the use of falling weights, of which the head is made in either round or wedge shape. Under falling speed of the weight varying from 140 to 328cm/sec and the temperature ranging 0 to 100°C, the shape of the broken parts of the fibers is observed with microphotographs. The following results are obtained: (1) In all cases of fiber rupture by falling impact of weight having either a round or wedge head, and with the falling speed of 140_??_328cm/sec, the broken parts show a melting type rupture, (2) The melted area increases with the rise of temperature. (3) The melted area increases with the decrease of the falling speed, but this tendency is not bound at high temperature beyond 70°C. (4) The melted area increases radically at beyond a certain temperature depending on the kind of fiber and the shape of the falling weight. This phenomenon may be interpreted by a thermal characteristic of the fiber. (5) By observation with a polarized microscope, double refraction is also shown at the ruptured part which seem to be melted. This shows that the interior construction of these parts is still orientated.