Atactic and isotactic polypropylenes were fractionated by means of successive solvent extraction method using saturated hydrocarbons at their boiling point. Physical properties of each fraction were evaluated in terms of isotacticity, viscosity average molecular weight, density, melting point, tensile stress-strain curve, infrared spectrum, x-ray diffraction and tensile storage and loss moduli. The tacticity of lower temperature fractions increases with extracting temperature, while the viscosity average molecular weight stays almost constant. The stereoregularity of each fraction was estimated qualitatively by using Fiory-Coleman's theory on sequence propagation probability and isotacticity, and it is concluded that each fraction is of block polymer nature composing of isotactic and atactic sequences. The drastic change of tensile storage modulus was observed at about 70% crystallinity and is explained in term of Fujino's theory of simple mechanical mixture of island-matrix mixing. It is concluded that the change could be explained in term of phase conversion from crystalline islands in amorphous matrix to amorphous islands in crystalline matrix due to hexagonal close-packing of crystalline phase at about 70% crystallsinity. Tensile stress-strain bahavior of each fraction shows that the higher tho isotacticity the larger the yield stress, initial tensile modulus add ultimate energy resistance, even if the viscosity average molecular weight bo same.
It is empirically known that some organic compounds can be used in the case of dyeing polyethylene-terephathalate fiber as the accelerants (termed “carriers”). It may be thought that the glass-transition temperature of the fiber decreases with sorbing of the organic compounds, because the polymer chain may be loosened by sorbed compounds, and the dye molecule may diffuse more easily into the fiber. In this study, the shrink-initiation temperature of the fiber was taken as the measure of the glass-transition temperature and the effects of various kinds of organic compounds on decreasing the glass-transition temperature was examined for more than 50 compounds. The results obtained are that the shrink-initiation temperature decreases proportionaly to the amonut of sorbed compounds, within a limited width, having a little relation to the kind of compounds. And this relation appears most linearly when the amount of sorbed compound is represented by mol/kg fiber. This relationship may be interpreted in terms of the Fujita-Kishimoto's equation of free volume concept in polymer-diluent system. It may be concluded that the organic compounds sorbed on polyethylene-terephthalate fiber make some bonds with polymer chain and increase the mobility of the polymer chain.
Hereunder is given a report of observations of cotton fibers performed in order to obtain the gradual changes of their surface during the process of mercerization. The fiber surface was carefully observed through an electron microscope. Conditions of mercerization is changed by the concentration of sodium hydroxide, and the time and temperature of the treatment. The following facts have been elucidated as the result: 1. The deep original wrinkles, each 0.1_??_1 microns apart swell under alkali action and have a tendency to vanish rapidly. Under ordinary conditions they vanish completely. 2. The larger part of cuticle layers that form the surface of raw cotton fiber are removed during the preliminary scouring process and they are completely removed under the mercerization treatment. 3. The microfibrils lying within the cellulose layers swell under alkali action, giving the surface of the fiber consequence granuler or porous appearances. The surface structure mentioned in heading 3 above has been found characterictic to cotton fibers whenever they are subjected to mercerization treatment, not only being the case with scoured cotton but with raw cotton or with dewaxed cotton. What is to account for this characterstic change of the surface structure of cotton fibers? Taking into consideration the results of the experiments worked with dyestuff absorptiveness on mercerized cotton fibers, it is concluded as follows: Mercerization process presupposes alkali action. The alkali-soluble hemicelluloses within the fiber oozes out to the surfaces, there to agglutinate on them instead of being washed off.
Frictional force F of fibre is given by F=fRN as a function of load R, where f and N are constants. N is especially called friction index. The changes of the friction index of a fibre lubricated with various lubricants have been studied. 1) On the friction of the fibre lubricated with a good lubricant like stearic acid, the shearing strength of the lubricated surface which is under lower pressure than on metal, does almost not increase as the pressure increases. The friction index in this fibre, therefore, is only slighthy larger than in clean fibre. 2) The friction index, which the fibre lubricated with a poor lubricant like caproic or capric acid, is larger in the index of dry or well lubricated friction, and this index is possibly larger than 1. 3) On the friction of a fibre lubricated with a poor lubricant, the following formula is obtained: where, F: the frictional force, R: the load, sf: the shearing strength of the contact surface between the asperity of clean fibre and the friction substance, sl: the shearing strength of the completely lubricated surface, a, n, C: the constants, and aRn shows the area of the true contact of friction surface. It seems that sf has slightly less value than that of the shearing strength on dry friction.
Polypropylene fibre was fluorinated in nitrogen atmosphere with fluorine gas at 25°C. The effects of fluorination on the dyeing, physical and chemical properties of polypropylene fibre were investigated. The infra-red spectrum of fluorinated fibre container a broad and intense absorption over the 1040_??_1340cm-1 range. This absorption is very characteristic for fluorinated fibre, may be due to C-F linkage. The infra-red spectrum of fluorinated fibre treated with hot alkaline aqueous solution no longer displays the absorption over the 1040_??_1340-1 cm range and a new absorption at 3400cm-1, presumably arising from C-OH linkage, The results indicate that the C-F linkage in the fluorinated fibre is hydrolyzed by the treatment with alkaline solution. The infra-red spectrum of the fluorinated fibre treated with hot water is virtually identical with that of original fluorinated fibre, and it might be concluded that the C-F linkage in the fluorinated fibre is stable to hot water. By the treatment with hot water, however, the fluorine content of the fluorinated fibre is clearly reduced. This means that not all of the fluorine atoms in the fluorinated fibre are chemically bonded with the fibre, but some of them are merely adsorbed physically on the internal surfaces of the fibre, presumably in the form of HF. An examination of X-ray diagrams of polypropylene fibre, fluorinated polypropylene fibre and polypropylene fibre fluorinated and then treated with hot water shows that fluorination causes a decrease in the crystallinity of polypropylene fibre, and with hot water treatment an increase in that of fluorinated fibre. Fluorination has a pronounced effect on the dyeing properties of polypropylene fibre for cationic dyes. The fluorinated fibre could be easily dyed with cationic dyes from neutral or slightly alkaline dye-bath at 100°C. Under the acidic condition, however, the penetration of cationic dyes into the fluorinated fibre could not be attained even at 100°C. A probable mechanism involving the iondipole interaction between positively charged dyes and C-F groups in the fluorinated fibre suggest to explain the dyeing behavior of cationic dyes. The dyeing properties for disperse dyes are scarcely affected by fluorination.
The partial molal volumes of methane-, benzene-, m-benzenedi-, tolyl- and p-toluenesulphonic acids in water solution have been determined by a buoyancy method. Since the concentration of sulphonic acids in water solution used in this experiment was extremly dilute, the partial molal volume _??_0 might be identical with the apparent molal volume φ. The latter can be determined from the specific gravities and concentrations of the sulphonic acid solutions from the following equation: φ=(V-n1V0)/n2 (1) where, V is the total volume of solution containing n1 moles of water and n2 moles of solutes, V0 the volume occupied by a mole of pure water. An attempt has been made to estimate the partial molal volume of imaginary ion, -SO3-, in water solution on the basis of simple model. The partial molal volume of imaginary ion, -SO3-, has been deduced to 35ml/mole from the experimental data. The deduced value for -SO3- is considerably larger, but lower than the calculated value, 52ml/mole, from the bond distance of S-O, and the van der Waals' radius of oxygen following the treatment of Mukerjee. This discrepancy has been explained in terms of an “effective charge”, which is higher than the formal charge. The considerably larger partial molal volume of -SO3-, deduced from the experimental data, indicates that the water structure surrounding the imaginary ion may be broken by the weak ion-dipole interaction.
Investigations were made concerning the effects of various salt solutions on the quality of wool fibres in treating them with permanganate, and it was found that 2 mol solution of (NH4)2SO4 was most effective among the solutions for the treatment of shrinkproofing without such adverse effects as yellowing and poor handling. The cation of the salt solution did not show any special tendency to give a shrink-proof quality to the fibres, but its SO4= anion showed a tendency to improve the anti-felt treatment with permanganate. With the increased concentration of the same salt solution, shrink-proof property of the treated yarn becomes better, its tensile strength larger, and its alkali solubility less. This may be attributable to the fact that the reaction occurres with the increased concentration, apt to be confined to the surface of the fibres mainly by their deswelling action and does not substantially hurt the fibres themselves. Comparisons of physical properties between the wool fibres treated with KMnO4/(NH4)2SO4 solution and the ones treated with KMnO4/H2O solution revealed the following two facts. The static frictional coefficients between fibre-fibre as measured in their wet state by the Röder method showed an obvious difference from each other, at the same degree of concentration of KMnO4 the former showed a smaller value of μ2-μ1 and a better shrink-proof effect than the latter. Where the fibres were treated with KMnO4/(NH4)2SO4 solution, their values of both μ1 and μ2 became smaller up to 5% o. w. f. KMnO4; but beyond that point those values tended to became larger. This phenomenon could be seen from optical microscopic observations. The scale edges of the treated fibres tended to are collapse up to 5% o. w. f. KMnO4; but beyond that point said edges are sunken, and only the central part of the scale remaines to be seen. In the case of KMnO4/H20 solution, however, such a concave structure is hardly noticeable even if 30% o. w. f. KMnO4 solution was used. It was found that there is a linear correlation between the values of μ2-μ1 of the shrink-proofed wool fibres and the rates of its felting shrinkage. Half scales of wool fibres were first abrased by a glass edge along the fibre axis, and then the fibres were treated with KMnO4 solution in the presence and absence of (NH4)2SO4. In both cases, it was found that MnO2 is deposited on the abrased side (cortex) but rarely, if any, on the other side (coticle) before reduction. This clearly indicates that the cortex is more reactive than the cuticle.