The effects of dry heat setting and wet (aqueous) heat-setting on the fine structure of nylon 6 filaments are considered in relation to the physical and dyeing behaviors.
The heat-setting treatments were carried out at fixed length in the electric oven and the autoclave. The density, residual shrinkage, wide angle X-ray diffraction patterns, birefringence of the heat-set samples were measured.
The following facts were observed:
(1) The residual shrinkage of heat-set samples has linear relation to the crystallinity. The effects of temperature on the crystallinity and the residual shrinkage of heat-set samples are more remarkable in the wet heat-setting rather than in the dry heat-setting in the same temperature.
(2) The wet heat-setting exerts a peculiar influence only on the fine structure of the amorphous region, and has no effect in the crystalline region. But presumably the spacing of the crystal plane becomes shorter by wet heat-setting.
(3) The growth of the crystallites by heat-setting treatments are conspicuous and the crystallite sizes are related to crystallinity, regardless of the dry or wet heat-setting. The length of the amorphous region becomes shorter by the wet heat-setting treatments than by dry heat-setting, when compared in the same temperature. These results are contrary to the fact that the dyeability in higher in the wet set samples. It was suggested that the middle order region and the dyeable amorphous region are included in the so-called amorphous region, and by the wet heatsetting the dyeable amorphous region becomes loose while the middle order region transfers to the crystalline region.
(4) The orientation of the crystallite is increased slightly by the heat-setting, regardless of the dry or wet heat-settings. But in the case of the wet heat-setting, the orientation of the amorphous region is increased remarkably by the anisotropic swelling in water.

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Recently many kinds of heat-proof cloths with excellent heat-insulating effect have been produced for practical uses.
The heat-insulating effects on two points have been measured with the following results:
1) The rate of heat flow (on a plane) may be expressed by; where κ (kcal/m²•hr•°C)…the rate of heat flow caused by conduction and convection α₁ (kcal/m²•hr•°C)…the surface heat transfer rate (at high temperature end) α₂ (kcal/m²•hr•°C)…the surface heat transfer rate (at low temperature end) λ (kcal/m•hr•°C)…the thermal conductivity of the sample δ (m)…the thickness of the sample The rate of heat flow (λ/δ) by heat conduction was measured and the value of (κ) was obtained.
2) The rate of heat flow by radiation was measured for two cases;
A) a thin sample and B) a thick sample
Applying the passing radiation method to the former and the reflection method to the latter, differential coefficients of both a temperature rising curve and a cooling curve of the heatreceiving plate were observed. Then the rate of heat flow by raddiation was calculated.
3) After the experiments mentioned above, the heat-insulating effect of the heat-proof cloth by conduction and convection showed the least difference among samples measured, because of the control by the heat transfer rate of the surface (α).
If radiation does not pass through the heat-proof cloth, the smaller the radiation coefficients are, the better the heat-proof cloth is.

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A sample of polyacrylonitrile of molecular weight 7.8×10⁴ was dissolved in 70% nitric acid and spun into filament through a glass nozzle of 0.5mmφ, using 30% nitri_??_ acid as a coagulating bath. Three samples of filament were prepared by two-stage stretching: the first stretching was made in water at 60°C, followed by drying, and the second stretching was made in the boiling saturated solution of ammonium sulphate. The total degrees of stretching were 12.3, 18.5 and 23.1 folds. These samples were shrunk freely by heating in water at T=60_??_170°C; the degree of shrinkage S amounted to about 20% at maximum. The change in the orientation degree was traced dichromatically (f_D) and by X-ray method (f_x). The following results were obtained:
(1) Plotting logS against 1/T, a linear relation is found, on which 4 transition points appear at about 94_??_96, 115, 130_??_140 and 160°C respectively.
(2) f_D-T is also linear with transition points on it; the transition temperatures correspond well with these on the logS-1/T line with a few exceptions.
(3) f_D drops from 0.80 to 0.15, while f_x from 0.89 to 0.86 after the maximum shrinkage.
Consequently it may be concluded that the thermal shrinkage occurs with disorientation which was predominant in the amorphous region, and it proceeds discontinuosly at the transition points.

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Undrawn polyester monofil of 0.40_??_0.42mmφ was carrier-dyed with Disperse Red R and stretched by 5.1_??_5.2 fold. This filament shrunk freely by heating in water at T=50_??_170°C for 3min. and the change in D°f_D (dichroic orientation degree), f_x (X-ray orientation degree), and S (thermal shrinkage) were traced. Plotting these parameters against 1/T°K, the following results were obtained:
(1) log S-1/T is linear and transition points are found at about 80°C, 140 and 150°C on that line.
(2) f_DD°-1/T is also linear and 3 “knicks” appeared at the temperatures corresponding to the above transition points.
(3) S amounts to about 20% at maximum, when the dichroic orientation degree drops to 0.1 from 0.38, the initial orientatation degree, while f_x is 0.93_??_0.92 and keep nearly unchanged.
It is concluded that when the polyester monofilament (tetron) shrinks freely, the amorphous region disorients predominantly, while the crystalline orientation is kept nearly unchanged. The “knick” points on the log S-1/T line is meaningful, although the linear relation of log S-1/T has not been proved theoretically, and shrinkage proceeds discontinuously at the “knick” points.

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(1) Relation between The Effect of Wevelength and The Viscosity Behavior
DPs of two kinds of samples irradiated by λ 1850 A and λ 2537 A for different length of time, are determined by their viscosity of cuprammonium and nitrate-acetone solutions. Then, DP is plotted against time of exposure. The results show that in the case of λ 2537 A irradiation, the shapes of degradation curves obtained by these two measuring methods are substantially the same and that in the case of the λ 1850 A irradiation sample, the curve obtained by cuprammonium viscsity measurement gradually decreases with time of exposure, while the curve by nitrate-aceton viscosity method initially falls and hen becomes parallel to the axis of exposure time. These experimental facts lead to the conclusion that (1) on irradiation by λ 1850A in vacuum, direct scission of cellulose chain molecule by photchemical primary dissociation predominates at the initial stage of degradation, but during prolonged exposure, the formation of alkali sensitive linkage by intramolecular bond breaking is the main reaction, and (2) on the other hand, irradiation by λ 2537 A in oxygen atmosphere degrades cellulose without formation of alkali sensitive linkages.
(2) After Effect of Photodegradation of Cellulose
The after effect of photodegradation of cellulose by λ 1850 A a nd by λ 2537 A irradiation is examined during the storage in oxygen atmosphere and in vacuum desicator. In both cases, 4-hour irradiation is employed.
The results show that there is no after effect in each case within 20 days, contrary to the van Nostrand's findings.
(3) Effect of Light Intensity upon Photodegradation of Cellulose
Effect of light intensity upon initial stage of photodegpadation of cellulose has been reported for two different wavelengthsn, i.e., λ 1850 A and λ 2537 A. The number of scission per molecule is used as a measure of photodegradation, and R/I and R/√I are calculated, where R is the rate of photodegradation and I the light intensity. It was found that in both cases, only R/I gives a constant value in various light intensities, indicating that the rate of photodegradation is proportional to the light intensity I and not to √I.

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The kinetics of diffusion of dye in polyester substances were studied by the method of rolling film.
Measurements of concentration of dye bath, surface dye concentration and diffusion coefficient were made on the purified mono azo and diphenyl disperse dyes.
Partition coefficient and activation energy for diffusion have been derived. On the basis of these data, the following results were obtained:
(1) It is presumable that the dyes diffuse into polyester substance as single molecules.
(2) The larger the dye molecule the slower is its diffusion rate into the fiber structure.
(3) The infiuence of partition coefficient on the diffusion into polyester substances is small.

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The reducing mechanism of azo dyestuff has been indicated to be important for its carcinogenic process and the fading of the dye on fibre. The reducing process, however, makes difference by the formulla of azo compounds, the kinds of reducing agents and other conditions. To investigate those relations, the effects in the process were detected by the paper chromatography and the paper electrophoresis.
Such dyes containing the coupling components as crocein acid, G-acid, schaeffer acid and R-acid were used. Those azo compounds were attacked in the azo linkage to produce amine generally by stannous chloride, and hydrazo compounds in many cases by sodium sulfite. The good separation of the free dye and the hydrazo is caused by employing the developer of mixedsolution-buthanol, pyridine, water, 6:3:4-in the paper chromatography. Hydrazo compounds are not stable and reproducted the azo linkage easily by air oxidizing. The dye having R-acid produces twe amines by sodium sulfite.

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Continued from the proceeding studies, the authors describe the steeping method for the comparative measurements of wetting of the fiber assemblies by distilled water, constructing the assemblies in different stuructures and from various kinds of fibers. An improved hydrometer method was used in which the strain meter and the pen oscillograph were used for the measurement of weight of the sampless. The types of sample fibers and the method of scouring are described in the previous articles. Five different degrees of porosities (degree of opening) of fiber assemblies were obtained by stuffing the specified quantity of each fiber sample into the cylindrical containers which were made from stainless steel wire netting and in five degrees of capacities.
The sample fiber assemblies was steeped in distilled water and then hung on the arm of straingauge. The relationship between the weight of sample (W_s) and the elapsed time (T_s) was recorded on the oscillograph chart. Thus, as in the hydrometer method, the relationship between the apparent density of sample (D_ap) and the elapsed time (T_s) were obtained on various types of fibers and on different degrees of porosities. Moreover, the dependency of the retained air index (V_a/V_c) of the assemblies on the elapsed time could also be obtained from these data and this could be used as an index in an analysis of the wetting behavior of the samples.
The great varieties were found on the values of D_ap and V_a/V_c for each elapsed time with the types of fiber in the case of the same degree of porosity: the assemblies of acrylic, absorbent cotton, rayon and Vinylon were penetrated very rapidly, that of acetate and nylon ranked next, and polyester the last. Finally, penetration of polypropylene and scoured wool by water was found to be exceedingly small. The characteristic wetting behavior of each fiber assembly could be found by careful examination of the data. The assembly of acrylic was penetrated very rapidly and almost perfectly at all ranges of porosity examined. The property depends, however, on the type of components which has been used in the copolymerization, in small quantity, with polyacrylonitorile. The wetting behavior of assemblies of various kinds of acrylics will be dealt with in a next article.

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