The behaviors of melting in copolymers may be affected by the copolymer compositions, the crystalline sequence length and its distribution, the stereochemical relations among the repeating structural units and the conditions of crystallization, etc.. Therefore, it may be difficult to deduce explicit expressions on melting in copolymers. In this work, the effect of crystalline sequence length and its distribution on the melting behaviors of copolymers composed of units of type A, capable of crystallizing and other units B incapable of crystallizing, is discussed in particular from a standpoint differing from that of our preceding paper. Derived equation relating to the crystallinity against the absolute temperature for random copolymer was in accord with the relation obtained in the preceding paper. If considered the Gibbs free energy difference between the crystalline regions and the amorphous regions as a variable quantity together with the amorphous fraction and the absolute temperature, the derived equation may be valid for fair explanations of the experimental relations between the crystallinity and the absolute temperature.
Recently, several kinds of twistless-yarns (Tex-Ja Yarn, Bob-Tex Yarn, T. N. O. Yarn etc.) and their fabrics have been developed. This paper reprts on the breaking strength of twistless-yarn fabrics. The twistlessyarns (T0) were produced by means of the apparatus shown in Fig. 1. The conventional yarns (T2.5 and T6.5) of twist factors 2.5, 6.5 were produced by ring frame. They were then woven into fabrics and washed to remove the adhesive. These fabrics are named, T0 Fabric, T2.5 Fabric and T6.5 Fabric respectively. Their loadelongation curves are shown in Fig. 6. Defferent yarn densities of the T0 and T2.5 Fabrics are shown in Table 2, and their load-elongation curves are shown in Fig. 7 and Fig. 8. The breaking strength per yarn in fabric are given in Fig. 9 and Fig. 10, for comparison. When the twistless-yarn fabric is elongated, compressive forces work at the intersecting points of the yarn in the fabric, and therefore inter-fiber frictional force increases. From this point of view, the compressive forces at one of the intersecting points of the yarns in fabric were calculated. (formula (3) (4) and Fig. 15) Futhermore, from the relationship between the inter-fibre frictional force and the yarn strength, the breaking strength per yarn in the fabric was calculated and the calculated values are compared with the experimental data.
The effects of molecular orientation on the dynamic viscoelastic properties of the biaxially stretched polyvinylchloride films were investigated. The specimens were prepared by stretching of T-die extruded films to various ratio by different methods at 95°C at a rate of 400%/min in a circulating hot-air bath. The stretching methods of films were uniaxial with the free or constant width, two-way successively biaxial and simultaneously biaxial stretching. The temperature dependence of tan δ, dynamic modulus E′ and dynamic loss E″, of the stretched films were measured at 100Hz by a Viscoelastic Junior Spectrometer. The following results were obtained: (1) The stretched films by different process show changes of characteristic dynamic viscoelastic properties due to the orientation. (2) The peak values of tan δ, E′ and E″ along the stretching direction (MD) were higher than those along the transverse direction (TD) for the uniaxially stretched films. These tendency is observed also in the two-way successively biaxially stretched films. However, the values along MD and TD are equal when the films is biaxially stretched in equal extent along MD and TD. This is same for all stretch ratios in the case of the simultaneous biaxial stretching. (3) The molecular chain in uniaxially and biaxially stretched films seem to be similarly extended, which is different from the crystalline polymer films. (4) The temperature of tan δ max which corresponds to the glass transition changes depending on the stretching conditions. This is due to the fact that the temperature depends not only on the degree of orientation but on the orientation mode and the orientation direction.
Temperature characteristics of dynamic modulus E′, and dynamic loss E″, of polypropylene (PP) monofilament grafted with acrylic acid and further treated with metallic salts or tris (1-aziridinyl) phosphine oxide (APO) were measured using the direct-reading dynamic viscoelastometer at 110 c. p. s. over a temperature range from-20°C to 200°C. Primary peak in the low temperature side of PP (da), obtained from the temperature characteristic of E″, tends to shift to higher temperature side and to decrease its intensity by the grafting with acrylic acid. These tendencies may be caused by the increased restriction of molecular chains of PP in the amorphous region by some crosslinking action of the dimesized polyacrylic acid chains of the grafted branches. The crystalline absorption (dc) of PP in the high temperature side (110°C) is broadened for the samples with a low degree of grafting due to the superposition of the glass transition of polyacrylic acid and of the dc transition of PP, but new well-defined absorption peak is appeared at 140°C for the samples with a high degree of grafting. The location of this higher temperature absorption, 140°C, is in accordance with the glass transition temperature of polyacrylic acid anhydride. The dc-absorption tends to shift to higehr temperature side and the intensities of both da-and dc-absorptions tend to decrease for the grafted samples treated with metallic salts in order to convert the carboxylic groups in the grafted chains to salt-forms, and the peak characteristic of the glass transition temperature of polyacrylic acid anhydride is almost disappeared with these samples. The E′ of these grafted and treated samples shows remarkable decrease in the vicinity of the temperature of the melt-dispersion of PP, though somewhat increased by the grafting and the treatment with metallic salts below this temperature. As for the treatment with APO, which may be expected to form crosslinking by covalent bond in the grafted material, higher E′ value is observed for the 36.9% acrylic acid grafted PP than that of the grafted PP untreated or treated with metallic salts even at the temperature as high as 200°C beyond the melt-dispersion temperature of PP.
The coagulation of viscous polymer solutions by diffusional interchange in a coagulation bath is an important step for fiber formation of wet-spun acrylic fibers. The analytical method to handle the coagulation process was investigated and it is pointed out that several equations derived so far for calculating the apparent diffusion coefficients of solvent and/or coagulant are not adequate, since the effect of contraction of the fiber during coagulation is not taken into account and under certain conditions, the equations become invalid. Therefore, the author has studied an adequate equation for calculating apparent diffusion coefficient of solvent, which is based on the amount of solvent transferred from the inside of fibers to the coagulation bath instead of the amount of solvent remaining in the fibers. The equation is expressed by: where t is the time, R the raduis of the fiber, λn the root of zero-th order Bessel function Jo (λn)=0, DLthe diffusion coefficient of the solvent.
Using the equations reported in the previous paper, the diffusion coefficients of solvent (DMSO) and coagulant (water) in filament during the coagulation process were calculated, and the effect of various spinning conditions on diffusion coefficients were studied and the relation between the diffusion coefficients and the formed structure were found. The obtained results are as follows: (1) Factors such as solid content in dope, temperature of coagulation bath and take-up speed of filament effect more strongly on diffusion coefficients than bulb stretch ratio. Apparent activation energies of diffusion are 4.72Kcal/mol for DMSO and 4.20Kcal/mol for water. (2) The diffusion coefficients of both DMSO and water show the minimum value at the bath content of 55% DMSO, where the volume porosity of as-spun fibers has the minimum value. This diffusional interchange explaines the dependence of volume porosity on the bath content. This phenomenon is considered to be caused by the formation of complex of one DMSO molecule and two water molecules, and the subsequent increase in viscosity of the liquid bath. In the bath content of about 55% DMSO, the complexes are considered to diffuse as coagulants into fibers more predominantly than water, while DMSO molecules diffuse out of fibers. (3) As the diffusion velocity becomes high, the fibers formed become porous and the fibrils and voids in the fiber become larger. This tendency is observed not only in DMSO-water spinning system, but also in ordinary wet spinning systems of acrylic fibers.
The diffusion of 1:2 type metal complex dyes into nylon film was measured by the roll film method. Dyes used were 15 symmetrical and 1 unsymmetrical 1:2 type metal complex obtained from substituted o, o′-dihydroxy or o-carboxyl-o′-hydroxy-benzene-azo-naphthalenes (metal is Cr3+, Co3+ or Al3+). Most of the symmetrical complex dyes were Drew-Pfitzner type (type_??_) and 2 dyes were Pfeiffer-Schetty type (type //). The substituted group is H, SO2NH2, SO2CH3, CH3, OCH3, Cl, NO2, phenyl or SO3H. Dyeing conditions were as follows: dyebath concentration 2_??_5×10-5 mol/l in water or in 25% ethanol-water, 80°C, 3_??_6 days. Diffusion profiles obtained can be divided into two parts, i.e., part I (boxlike diffusion) and part N (Fickian diffusion). Diffusion coefficients of both parts (DOI, DON and _??_N ) and the fraction of part I, (I/I+N), were calculated under the assumption that the diffusion of both parts occur competitively. Both parts were affected by the molecular size, shape and hydrophilic property of metal complex dyes, especially part I was influenced by the molecular size of the dyes. As the hydrophilic property of dyes increases, diffusion profiles of the dyes become nearly same as in the case of acid dyes. When the hydrophobic property of dyes increases, the amounts of dye uptake at the surface of nylon increase and diffusion profiles are nearly same as in the case of disperse dyes.