Graft copolymerization of acrylamide onto wool fibers by redox method (H₂O₂-NaHSO₃) was studied with following results.
1) The reaction rate of graft copolymerization is almost the same as that of the styrene grafting and the apparent activation energy of grafting calculated by Arrhenius equation is 11.1 kcal/mol. The reaction is acclerated by an optimum composition of mixed catalyst, H₂O₂ and NaHSO₃.
2) The molecular weight of the grafted PAM measured by viscosity method has a higher order than 10⁷ and the molecular weight obtained by low temperature reaction is greater than that by high temperature reaction at the same degree of grafting.
3) The reciprocal degree of polymerization of graft PAM. is proportional to the concentration of H₂O₂.
4) The mechanical properties of PAM grafted wool fibers are similar to those of the styrene-or PMMA-grafted wool though PAM is water soluble.

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Using the acrylic continuous filaments prepared by the dry spinning process as described in the previous report (I), cantilever drawing and drawing in steam and by a hot plate were done. Some physical properties of the drawn filaments were measured, also taffeta was woven of the drawn filaments. The acrylic continuous filaments were compared with other kinds of filaments. It has been found that:
1. In the stress-strain curves of the cantilever drawing, the region in which drawing tension remains constant is relatively narrow. So, the drawing must be uniform, and the non-uniform drawing accompanied by necking hardly occurs. The tension of drawing under usual condition is lower than those for polyamide and poly (ethylene terephthalate) by one order, and nearly equal to that for poly (vinyl chloride). It is considered that the drawing behavior of polyacrylonitrile is characteristic of atactic vinyl polymers.
2. It is possible to draw acrylic continuous filaments in steam at the high speed of 600m/min, but at the speed of only 100m/min by a hot plate. It is practically impossible to draw by means of a hot pin.
3. The filament drawn in steam has higher strength and lower elongation. It is a high orientation type, having higher value of shrinkage in boiling water, lower velocity of dyeing and lower number of twist. On the other hand, the filament drawn by a hot plate has lower strength and higher elongation. It is a low orientation type, having the same velocity of dyeing as that of the staple fibre. Although in the drawing by a hot plate both the temperature of heat treatment and the contraction during heat treatment are much larger than those of drawing in steam, the shrinkage in boiling water still survives, indicating poorness of heat-setting property. It may be considered that the poorness of heat-setting property is the characteristic of atactic vinyl polymers.
4. The stress-strain curve of the drawn acrylic continuous filament lies between those of poly (ethylene terephthalate), nylon and rayon, acetate.
5. Compared with taffetas woven of various filaments, the taffeta of acrylic continuous filament is situated between poly (ethylene terephthalate), nylon and rayon, acetate in strengths and wash and wear property. However, it is distinctively the most excellent in touch and the silkiest of these man-made filaments. In addition to this, crepes are easily woven of acrylic hard twist continuous filament yarn. This is the property poly (ethylene terephthalate) filament does not have Further, dyed with cationic dye, acrylic filament is superior to poly (ethylene terephthalate) and nylon filament in brightness of color.
conclusion: Acrylic continuous filament is the most aesthetical synthetic fibre.

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The conditions for modifying a thermo-contractible acrylic continuous filament to stretch yarns by the air-jet false twist method were investigated, and the stretch yarns obtained by the optimum condition as well as the fabrics knitted out of the yarns were compared with those of poly (vinyl chloride) and poly (ethylene terephthalate).
The factors taken up in the experiments of the modifying conditions were (A) temperature of the heater, (B) distance between the air-jet nozzle and the hook below it, (C) velocity of winding, (D) pressure of compressed air, (E) rate of overfeeding, and two-factor interactions A×C and D×C. The characteristic properties measured were strength, elongation, rate of fulling, elongation ratio of crimp, elasticity of crimp, and residual twist. An orthogonal divided 3¹³ type experiment gave the following results:
1. In principle, when the combination of level of factors gives the larger false twists, the higher values can be obtained on the rate of fulling and on the elongation ratio of crimp of the stretch yarn. It is inevitable, however, that the strength and the elongation of the stretch yarns is deteriorated. On the conditions in which the extreme twists are given, on the contrary, the elongation ratio of crimp becomes lower because of insufficient untwist. In general, less false twist is required for acrylic filaments than that of poly (vinyl chloride).
2. Compared with the stretch yarns of poly (vinyl chloride) and poly (ethylene terephthalate), the acrylic stretch yarns have lower strength and elongation, higher rate of decrease in strength, and lower elasticity of crimp. Compared in knitted fabrics, the acrylic ones have the highest value of bulkiness after fulling, though the value becomes lower after scouring because the fabrics are elongated. The compressive elasticity of the acrylic knitted fabrics is about the same as those of poly (vinyl chloride) and poly (ethylene terephthalate), or superior after fulling as well as scouring.
3. Worn as an under wear, the acrylic stretch yarns do not give the feeling of power to human body as do those of poly (ethylene terephthalate) that have larger elongation ratio of crimp.

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Light microscopic observation was made to confirm polyurethane deposited on wool fibre by various procedures. (Ref. Report I of this series)
In Procedure 1, time-shrinkage curve of the wool treated with adduct from P. P. G. 400 shows that the felting takes place after an induction period.
This felting seems to begin when some of polymers are removed, because microscopic observations shows that some of the polymer block could be removed easily from wool fibres by rubbing between two glass plates in water.
When wool in top sliver is treated, the adducts prepared from P. P. G. 1000 or 2000 form thin films only over the wool surface cannot be removed, making the wool unshrinkable; but in a fabric treatment, the fibre bonding occurs.
When the wool is dissolved in a solution of potassium hyroxide after having been treated with polyurethane in a solvent, the polyurethane residue is deposited only to the edges of scales and a sheath is not formed.
In Procedure V, droplet formation of polyurethane is observed owing to retarded evaporation of its solvent.

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Glycidyl methacrylate was graft polymerized onto cotton by simultaneous Co⁶⁰ γ-ray irradiation in the presence of air at room temperature. During the graft polymerization, epoxy rings in the grafted side chains did not open by the irradiation of the total dose below 2×10⁵ r, but insoluble homopolymer was formed above this dose.
As the grafted cotton has reactive epoxy rings in the grafted side chains, long chain cross-linkings can be introduced to the cotton cellulose using these reactive groups.
The crease recovery and some tensile properties of the grafted and cross-linked cottons were examined.
The results may be summarized as follows:
(1) Dry crease recovery of the grafted cottons cured after treated with H₃PO₄-methyl ethyl ketone, HCOOH-morpholine and ethylene glycol-BF₃ respectively increases considerably, but no improvement is observed in wet crease recovery.
(2) Curing of the grafted cottons treated with ethylene diamine or bis (hydroxy ethyl) sulfone gives no effects on improving both the dry wet crease recoveries.
(3) Curing of the grafted cottons treated with Zn(BF₄)₂ solution gives a considerable improvement in both the dry and wet crease recoveries.
(4) Though the strength of warp of the grafted cotton fabric is decreased by cross-linking, the tensile damage of cotton by cross-linking is remarkably prevented by the grafting.

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In order to improve the dry-heat process (pad & cure process) with urea and phosphoric acid which is known as a flameproofing treatment of cotton fabrics, the wet-heat process in some organic solvents were examined, and flameproofing effect of cotton fabrics treated by this method was compared with that by the dry-heat process. Among polar organic solvents used in the wet-heat process, dimethylformamide (DMF), dimethylacetoamide, formamide, anilin, and γ-butyrolacton were found to be useful to obtain phosphorylated cottion fabrics with relatively small loss of tensile strength. It was found that there is some optimum ratio among cellulose, urea, phosphoric acid, and DMF, and that the addition of some amines, hexamethylenediamine for example, is effective to prevent tensile strength from depression.
The thermogravimetric analysis shows that the larger the percentage of combined phosphorus, the larger is the weight of the residue after decomposition, and the flameproofing property is proportional to weights of the residues. Insufficient washing of the products leads to the lowering of decomposition temperature. However, the decomposition temperature of the well washed sample is nearly equal to that of the untreated fabrics. This fact disproves the previous assumption that the flameproofing effect is exerted by the carbonization of cellulose, and that the lower the carbonization temperature, the larger is the effect.

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In the preceding papers (I-III), the authors reported the wetting characterisitic of various fiber assemblies finding a notable fact that the assemblies from two kinds of acrylics have an unexpected good wettability. In order to examine this fact in more detail, the wettability was investigated on the assemblies of acrylic fibers including five kinds of products manufactured in this country. Data on rayon and polyester fibers were also obtained for comparison. Each sample was scoured with aqueous solutions of non-ionic detergents and then repeatedly rinsed with distilled water and finally dried and conditioned. The time dependence of upward penetration of distilled water into the fiber assemblies was measured by means of an apparatus described in previous paper (I).
The assemblies of acrylics are generally fairly wettable except the modacrylic fibers and the decrease in openness (porosity) of the assemblies give rise to an increase in the penetrating quantity in the range of porosity examined. The volume of penetrated distilled water varies with the kind of fibers in the case of compact assemblies of small porosity, but the difference in the wetting behavior is exceedingly small in the case of porous assemblies of large porosity.

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