Mechanical primary dispersions of polyethylene terephthalate fiber and polyethylene terephthalate-isophthalate copolymer fiber are measured and the cause for the difference of loss peak temperature between homopolymer and copolymers is discussed. It is found that the glass transition temperatures of these copolymer at amorphous state conform to Gordon-Taylor's equation. The difference in glass transition temperature between amorphous homopolymer and amorphous 9/1 copolymer (terephthalate 9: isophthalate 1) is 2 or 3 degrees. The results of dynamic mechanical measurements about undrawn fiber produced by melt spinning show that tho loss peak temperature of 9/1 copolymer is only 4 degrees lower than that of homopolymer. But for drawn and drawn heat-treated fibers, the loss peak temperature of 9/1 copolymer is found to be about 20 degrees lower than that of homopolymer. The data of X-ray small angle scattering intensity, half width of (010) plane of X-ray diffraction and width of mechanical primary dispersion seem to suggest the following explanation: the density of amorphous region of copolymer is smaller than that of homopolymer and therefore the restriction of chain motion in amorphous region by the existence of fine crystallites is looser in copolymer fiber than in homopolymer.
Various dopes of commercial cellulose triacetate flakes of two different DP dissolved in CH2Cl2-CH3OH (9:1) solvent were spun into CH3OH-CH2Cl2 coagulant, and their spinnability curves are shown as the highest and lowest possible reeling speeds vs. CH2Cl2 concentration in the coagulant. The spinnability (the highest possible reeling speed) decreases to minimum and then increases to maximum with increasd CH2Cl2 concentration in the coagulant. The minimum lies in 10_??_20 vol % of CH2Cl2, and the maximum in 30_??_40 vol %. The tenacity and the elongation of the spun filament at a certain reeling speed chang also with increase of CH2Cl2 concentration in the coagulant. Their minimum and maximum correspond respectively to that of the spinnability. Tenacity takes a maximum at about 80m/min, elongation at 10m/min. A density and a molecular orientation of the spun filament also change by increasing CH2Cl2 concentration in the coagulant, and their minimum or maximum corresponds respectively to that of tenacity, elongation or spinnability. As the coagulant temperature rises, the maximum or the mininimum spinnability curve corresponds to lower CH2Cl2 concentration in the coagulant, the elongation of the spun filament increases, and the cross-sectional shape is more rounded. The optimum conditions of the spinning in this experiment are considered as follows: triacetate flakes: DP 310, AcOH value 60.6%; dope concentration: 23% in CH2Cl2-CH3OH (9:1); coagulant: CH2Cl2 34 vol % in CH3OH-CH2Cl2, 25°C; reeling speed: 40_??_80m/min. Tenacity ang elongation of the spun filament at the optimum condition are about 2.5g/d, 20% while a commercial acetate has about 1.5g/d, 24%, Arnel 1.3g/d, 30%.
The paper deals with the transformation of hemicellulose from γ-cellulose to β-cellulose during cooking, contrary to the ordinary conception. β-Cellulose is little present in softwood but much in hardwood. Hardwood pulp, especially hardwood sulphate pulp, contains larger amouns of β-cellulose than γ-cellulose. It is due largely to the facts (1) the small amount of glucomannan which has larger affinity to water and, (2) rather lower degree of hydrophilic properties of xylan complex, It is generally accepted that α-cellulose is decomposed to β-cellulose, and furthermore, to γ-cellulose during cooking of softwood. Nevertheless, in view of hemicellulose, by cooking, especially by sulphate cooking, some of γ-cellulose in the wood is changed to β-cellulose, because of the decreased amount of hydrophilic residues of hemicellulose molecules, in spite of the decreasing in degree of polymerization of these molecules.
Amilan (Nylon 6, Toyo Rayon Co.) was dyed by the so-called changing dyebath method which is a variation of the infinite dyebath method, adjusting the pH in the dyebath with such a concentration of phosphate buffer solution that the salt anion did not affect the dye uptake on the fibre. In this method the dyebath was changed frequently with fresh dye liquor having the same composition as the initial one as the dyeing proceeds, repeating this process until the equilibrium was attained. By the above method we are to obtain the dyeings which are in equilibrium with any arbitrary concentration of the dyebath. In the present experiment, however, the dyebath concentration was kept in the pH range 2-8. We have calculated the affinity of dye acid by the application of Gilbert-Rideal equation to our results. The affinities of 14 acid azodyes, which were determined by this method at 59°C, were compared with those measured by usual dye acid adsorption method. This new method was found to be useful for the determination of affinity, since it shortenes the time of attaining to the dyeing equilibrium to 1/5_??_1/3 times of that required in the case of dye acid adsorption method, besides the experiment could be more easily performed. From the fact that for 10 out of 14 dyes the saturation values agrees with each other, being 4.71×10-2 eq./kg., ± 2%, it is deduced that the sites (terminal amino groups in Amilan) would be stoichiometrically occupied not only by monobasic dyes, but also by polybasic dyes. Moreover, it was observed that the affinity increases with the molecular weight of dyes; i.e., when a benzene ring is substituted with a naphthalene ring, it increases by 2.1 Kcal. and 1.7 Kcal. for monobasic and dibasic dyes respectively. Also if an additional benzene-azo group is introduced into the molecules, the increment of affnities becomes 3.5 Kcal. and 3.0 Kcal. for respective cases.
According to the previous papers1)-7) on model substances, it was concluded that α-CH…X-Dye type hydrogen bonding made an important contribution to the interaction between aminoanthraquinone type disperse dyes and cellulose acetate fiber and the like. In the present paper, the same problem is discussed on actual dyeing data. (1) Saturation values of this type of dyes on cellulose acetate do not contradict with the result from model substances. Hence, it is concluded that α-CH…X-Dye type hydrogen bonding plays an important part in actual dyeing of cellulose acetate fibre, too. (2) The correlation between saturation values on acetate and on Nylon is not regarded as nonexistence. In view of this fact and α-CH groups in Nylon, it may be expected that the same bonding has a possibility to act a role in Nylon dyeing. But, the significance of the bonding in Nylon dyeing is far smaller than in acetate dyeing. (3) Saturation value of anthraquinone on Terylene is nearly equal to that of 1, 4-diamino-derivative. It may be assumed that the same bonding may make a contribution to Terylene dyeing, too. (4) Because of the structural analogy, it is assumed that the dyeing mechanism of acrylic fibres is similar to that of acetate fibre. A method to improve the dyeability of acrylic fibres is suggested from this assumption.