Dyeing enhances the crystallization of Nylon-6 induced by stretching or by heat treatment. This effect was investigated by measuring the density, X-ray diffraction and dye desorption for Nylon-6 samples, which were (1) dyed with Orange II (C. I. Acid Orange 7) after stretching in water at 90°C or (2) stretched after dyeing under the same conditions. The results indicate that dye molecules sorbed in the amorphous regions of Nylon-6 promote the crystallization by stretching or by heat treatment. Crystallization by stretching lessens the amount of desorbed dye, indicating a fraction of the dye is released from the film by the stretching.
Polyester fiber was pretreated with organic solvent/water solutions of various compositions. The organic solvents used in this experiment were benzyl alcohol, n-butanol, and N, N-dimethylformamide (DMF). The dyeing behaviors of the pretreated fibers with 1, 4-diaminoanthraquinone in water were studied with reference to changes in the fine structure of the fibers. Also density and X-ray diffraction of the fibers were investigated as a measure of crystallite region. The dye uptake increased in the order, fiber pretreated with water<untreated fiber<fiber pretreated with aqueous 5% benzyl alcohol solution<fiber pretreated with benzyl alcohol<fiber pretreated with aqueous 90% benzyl alcohol solution for benzyl alcohol; fiber pretreated with water<untreated fiber_??_fiber pretreated with aqueous 5% butanol solution<fiber pretreated with butanol<fiber pretreated with aqueous 90% butanol solution for butanol; and fiber pretreated with water_??_fiber pretreated with aqueous 5% DMF solution<untreated fiber<fiber pretreated with aqueous 90% DMF solution<fiber pretreated with DMF for DMF, indicating that the dye uptake increases with the increase in the crystallite growth. This might be due to the fact that the recrystallization process during the pretreatment with organic solvent/water solutions leads to an increase in the amorphous volume and then a large increase in the dye uptake. Also the rate of dye absorption increased and the dyeing transition temperature decreased with the pretreatments. The results obtained are briefly discussed in terms of the plasticization of the fiber structure formed during the pretreatment.
Radiation effects on poly(m-phenylene isophthalamide) (m-PIA) and poly(p-phenylene terephthalamide) (p-PTA) fibers have been studied by use of γ-rays and electron beams. Deterioration in the mechanical properties was not observed for m-PIA or p-PTA fiber even after irradiation of 1000 Mrad in vacuo. The presence of air favored the degradation of wholly aromatic polyamides as in case of aliphatic polyamides, although a much larger irradiation dose was needed for the former than for the latter to give the same degradation in mechanical properties by irradiation. The irradiation up to 1000 Mrad with electron beams in air revealed that p-PTA is more stable against irradiation than m-PIA. Viscometric studies were carried out on the irradiated fibers. Only a small change in viscosities of p-PTA was found even after irradiation both in the presence and absence of air up to a large dose, whereas in m-PIA, gel was formed after γ-ray irradiation of about 200 Mrad in vacuo and viscosity decreased to 40% of the original value after γ-ray irradiation of about 500 Mrad in air. No or a very small change in TGA curves for m-PIA and p-PTA was observed even after the irradiation of 1000 Mrad, showing that the irradiation at room temperature had no appreciable effect on the thermal degradation of these polymers.
Polyether-esters having the following chemical formula were prepared from p-hydroxybenzoic acid by the successive processes of halogenation, etherification, esterification and polycondensation: Effect of halogen substituent on synthesis and thermal properties of these polyether-esters were studied comparing with the polyesters (halogenated polyethylene terephthalates) reported previously. Intrinsic viscosities of polymers obtained were 0.42_??_0.58. Melting point measured by DTA decreased in the order of PEBCl2>PEBBr2=PEB>PEBCl4, and PEBBr4 had no melting peak. The area of the melting peak in DTA curves decreased in the order of PEB>PEBCl2>PEBBr2>PEBCl4. The ratios of melting points (K) of halogenated to non-halogenated polyether-esters were 0.95 -1.05. These values are larger than those obtained for halogenated polyesters. Weight loss at lower temperature increased and that at higher temperature decreased by halogen substitution. Ignition temperature and ignition lag increased by halogen substitution, and the polyether-esters had better flameretardancy than the polyesters. Solubility of polymers in organic solvents increased by halogen substitution, and halogenated polyether-esters had less solubility than halogenated polyesters.
Bleached sulfite pulp was dissolved with formaldehyde in dimethyl sulfoxide, and the optimum condition was determined in terms of sufficient dissolution and prevention of degradation of cellulose. Homogeneous acetylation of the cellulose dissolved was examined, and the cellulose acetates witl a degree of substitution up to 2.4 were obtained in recovery yield ca. 80%. The preparation of the cellulose acetate with a degree of substitution close to 3.0 was inferred to be difficult with the present method. The cellulose acetates with a degree of substitution 2.0-2.4 was found to be easily soluble in ethyleneglycol monomethyl ether and ethyl lactate, and practically soluble in acetone. The solubility of the cellulose acetate was found to be slightly poorer than that of partially saponified cellulose acetate with a similar degree of substitution, prepared from cellulose triacetate, suggesting that the degree of polymerization of the acetate was higher than that of the partially saponified one. The cellulose acetate film prepared from the ethyleneglycol monomethyl ether solution was slightly yellowish transparent, and brittle, but was hard and had rather high tensile strength. The results indicate that the cellulose acetate obtained with the present method may have a possibility for commercial application.
When a polyester sliver of 3500tex (50grain/yd) composed of 0.17tex (1.5den)×38mm crimped fibers was being produced by a flat card with cylinder speeds in 45, 100, 150, 200, 300, 400 or 500rpm, instantaneous photographs of fibers on the metallic wires were taken by using a flash gun of 10 microseconds through a specially-installed transparent plastic window in 200mm×100mm, attached on the front stripping door. In order to analyse the photographs of crimped fibers on the surface of the carding cylinder under the running condition, two kinds of simulation tests, a wind-tunnel test and a load-elongation test of single fibers, were carried out. From these experiments, we obtained the following conclusions. (1) Aerodynamic tensile force on a single fiber on the surface of the cylinder is about 1.5 to 3.0mg when the speed of cylinder is 150 to 300rpm. This tensile force is approximately one twentieth of the force to straighten out the crimp of the fiber. (2) The crimp per cent, i.e. the percentage of the reduced fiber length caused by crimp to the fully straightened fiber, is 17_??_12% under such low cylinder speeds as 45_??_100rpm, suggesting insufficient carding action under these conditions. (3) The crimp per cent is decreased from 10 to 7 by increasing the cylinder speed from 150rpm to 300rpm, indicating that fibers are carded being almost straightened, and efficient carding action is attained under this speed range of practical use. (4) Increasing the cylinder speed over 300rpm scarcely improves carding action because of the decreased decrement in the crimp per cent.
Polyester cotton blended fabrics prepared by using regular polyester (Es) or inherently flame resistant polyester containing polyarylphosphate (FR-Es) were finished with two flame retardants respectively, methylolated dime thylphosphopropionicamide (CP) or precondensate from tetraxis (hydroxymethyl) phosphonium chloride, urea and melamine (THPC precondensated). The following results were obtained from the flammability tests. 1. Oxygen index values (O. I) of 100% FR-Es knitted fabric, 100% cotton (Co) knitted fabrics treated with CP and with THPC precondensate are 0.295, 0.305 and 0.295 respectively. However, as the amount of another fiber blended increases the O. I decreases, and has a minimum. 2. CP treated fabrics of which Es (or FR-Es) percentage is less than 30 show good and durable flame resistance. 3. THPC precondensate treated fabrics show good and durable flameresistance in case of blended fabrics with Es percentage in less than ca. 50, or with FR-Es in less than about 67. In order to discuss quantitatively the scaffold effect in burning state of blended fabrics, the following equations on I. O were obtained as a function of cotton blended ratio. 1. Assuming that a fraction, α C, where α is the proportionality factor, of Es burns with cotton and no Es escapes from the burning by melting, This is the case for the fabrics with small Es blended ratio or E<αC. 2. Assuming a fraction, αC of Es burns with cotton and α fraction, β of the melt fraction, given by E-αC, of Es burns, This is the case for the fabrics with high Es blended ratio or E<αC. Here, γ=α-β-α•β C (E); Blended ratio of Co or Es, C+E=1, HC(E); Generative heat quantity by burning of Co or E respectively.Oc(E); Amount of oxygen required by burning of C or E. SN; Specific heat of nitrogen. T; Temperature difference. Dc(E); Released heat loss by the escape of generative gas in burning of Co or Es respectively. M; Heat quantity required to melt Es. Curves by equations are given in Fig. 5 (A), (B), (C), (D). From these results, the following conclusion can be obtained. FR-Es, the melt-facilitation type fiber, decreases the amount of the burning in the fabrics by melt and drop phenomena; its fiber shows apparently good flameresistance for 100% FR-Es or FR-Es fabrics containing very small amount of Co. However, in fabrics with more than ca. 30% cotton blended ratio, the flame resistant effect decreases rapidly by the increase in the amount of FR-Es burning with cotton in the fabrics.