Relaxation curves of wool fiber streched 10-25 per cent in aqueous media and phenol solution have been firstly determined. A conditioning temperature of 50°C was chosen, being as high as can be used without chemically damaging the wool fiber. Conditioning for half an hour at this temperature between measurements resulted in reproducible relaxation curves, as long as the period of extention of the fiber did not exceed 30 per cent.
An apparatus used is constructed with the magnetostriction constructed for measuring the relaxation of stretched fiber. The output from the strain meter is applied to inkwriting oscillograph from the start for 10 seconds and after this time range value of valve voltmeter was measured.
From the relaxation curves the reciprocal absolute temperatures corresponding to each test and the time required to attain the stress of 3.5×10⁵g/cm²_??_4.75×10⁵g/cm² are obtained. The points for each specified stress are seen to lie in straight line. From the slope of these lines, the energies of activation for relaxation process in water are found from each deformation (15, 20 and 25 per cent) to be approximately 10Kcal, 20Kcal and 25_??_30 Kcal.
The amount of breaking of hydrogen bonds depends on the concentration of phenol solution and temperature. With increasing temperature and concentration of phenol solution the rate of the stress relaxation becomes smaller than under the wet condition. Supplementary measurements of relaxation at various humidity were perfomed during 1/10sec_??_3000sec appling the former method. The each relaxation curve may be shifted log time scale and master relaxation curve may be constructed.

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We measured the creep of polyvinyl chloride fibers at 20°C and 40°C, and constructed the master creep curves by basing the key to the procedure for generalization upon O'Shughnessy's assumption that there exist an invariant pattern in logarithmic time for the entire delayed elongation process but that the time scale of the response, as well as its magnitude is dependent on stress.
The characteristic retardation times, Log τ, plotted as function of stresses, decreased linearly as stresses increased. The instantaneous elastic elongation E₀, plotted as function of stresses, increased linearly where stresses (S) were relatively small, but these relations between E₀ and S deviate from linear relations where stresses were relatively large and these deviations suggested the structural change in PVC fibers. The reciprocals of scale factors, 1/f, plotted as function of stresses well indicate the stress dependence of retarded elastic deformation of PVC fibers.

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Investigations were made on the dissolution rate of rayon pulp fibers, original and degraded, and the amount of amorphous regions in undissolved fibers in emulsion xanthation. The dissolution process of fibers was also observed microscopically.
The results are as follows:
a) The lower the degree of polymerization is, the higher the rate of dissolution becomes, and the range of optimum alkali concentration for dissolution becomes wide.
b) The amount of amorphous regions in undissolved fibers increases during xanthation, and is maximum when alkali concentration is about 10%.
c) Although xanthation reaction occurs only at the contact points of CS₂ droplets with fibers, occasional contacts are sufficient for the progress of xanthation. For this reason viscose-formation by simultaneous reaction in emulsion form takes place.

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We have bleached the sodiummonosulfite semichemical Japan beech pulp with hydrogen peroxide and by three-stage bleaching (chlorine, sodium hydroxide, calcium hypochlorite).
Taking the bleached semichemical beech pulp and bleached kraft pulp of beech, their mechanical strengthes were compared when bleached semichemical or bleached kraft pulp of beech were mixed with bleached sulfite pulp of red pine.
(1) When hydrogen peroxide is used as a reagent, the bleaching is most effective where 1% hydrogen peroxide is consumed by pulp. In Japan, on account of high market price of hydrogen peroxide, the elevation of brightness from 40 to 60 seems to be the economical limit.
(2) To elevate the brightness from 40 of the unbleached semichemical pulp to 80, it may be performed economically only by the three-stage bleaching.
(3) In the case of three-stage bleaching; By the first process by chlorine treatment, about 70% of lignin contained in the unbleached semichemical pulp is dissolved, but the dissolving of pentosan and other carbohydrates are not observed. By the second process with sodium hydroxide treatment, a certain amount of lignin, pentosan and other carbohydrate are dissolved. At the third-process with bleaching powder, the dissolution of lignin and pentosan was observed, but not the dissolution of other carbohydrate.
(4) The mechanical strengthes of the semichemical pulp bleached by the three-stage process are about 20% higher than those of the unbleached semichemical pulp.
(5) In the case of bleached semichemical pulp and the bleached kraft pulp having the same brightness, the mechanical strength of the former is two times stronger than that of the latter.
(6) In the case of mixing the bleached kraft pulp in the bleached sulfite pulp, the larger the content of the bleached kraft pulp is, the more the mechanical strength of the paper from the mixed pulp decreases, but the mixing of the bleached semichemical pulp shows the contrary result.

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Tire cords, whose results are known through the vibrator and rotor tests, are investigated by following ordinary mechanical tests:
For single fiber from the cord;
1, tensile test (room temperature and 110°C) and Young's modulus (static). For fatigued fiberafter vibrator test;
1. tensile test and Young's modulus (static). For cord;
1. tensile test (room temperature and bone dry) and Young's modulus.
2, creep and recovery.
3. repeated elongation tensile test (normal condition and bone dry).
Good correlation for the fatigue tests is obtained in following tests:
Tensile test for single fiber and cord at normal conditions, creep recovery for cord, and repeated elongation tensile test at normal condition.
Recovery mechanism for mechanical deformation of fiber contribute to fatigue life of the rotor and vibrator tests.

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In the previous reports, I reported that picoline-monochlor acetic acid was an excellent latent catalyst for the crease resistant finish with urea formaldehyde resin and obtained the patent for the method was described above.
In this report, the application of this method, i.e., the baking conditions, the concentration of resin solution, the composition and the amounts of the catalyst and the elapsed standing times of resin solution were studied as the preliminary experiment in the practical case, and I found that the method gave good effects of the above properties for the treated fabric and could be applied to the industrial operation.

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