It is useful to observe microscopic defects on fatigued nylon tire cord filament for investigation of fatigue mechanism of nylon fibre.
Nylon tire cords taken from two kinds of fatigued method are used, the one is the specimens which are fatigued by laboratory test (Goodrich type disc fatigue tester) and the other is those from run tires.
A number of oblique streaks were observed near the end of broken filaments which were fatigued by laboratory test. The similar streaks were observed on the fatigued filaments from run tires and predominated in the inner ply cords which mainly compressionaly strained. But, the latter were different in angle, density and grade of streaks from the former, because, the effect of strain would be different in run tire and laboratory tester.
Zaukelies observed a kink band produced by slip of crystallite when compression is given to nylon 6 and 66 filaments.
The oblique streaks which are observed on fatigued nylon filaments may be regarded with deformation of crystalline structure.

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We studied the various problems on the blends of atactic Polypropylene with SBR (Krylene NS and Philprene X-40) and NBR (Hycar 1042). Their blending ratios were 100/0, 95/5, 90/10, 85/15, 80/20, 75/25.The blends were made on the roll mill.
First, in the blended polymers the dispersion was observed with a phase contrast microscope, on the other hand, in the compounded rubber and vuicanized rubber, Mooney viscosity, mill shrinkage, extrusion properties, physical properties and swelling in toluene were measured. From the results, it was found that :
(1) It was found to be microheterogeneous dispersion from photographs taken by a phase contrast microscope, and the phase separation in solution was obserbed.
(2) Mooney viscosity and mill shrinkage decreased straightly.
(3) In the case of Krylene NS and Hycar 1042, extrusion properties and sheet surface were markedly improved in blending ratio about 85/15.
(4) In the physical properties of vulcanizate, linear relationships were found.

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The effect of various carbon blacks on the thermal polymerization of styrene and other monomers was studied.
Styrene could be graft-polymerized onto oil furnace blacks in the absence of initiators, but channel type blacks were less effective to form graft-polymer.
In addition, use of furnace blacks which were oxidized with hot nitric acid, treated with benzoyl peroxide or heated at 1, 500°C under nitrogen atmosphere was not desirable; it caused marked reduction in grafting ability. In particular, a significant drop in conversion rate of styrene in the presence of the carbon black treated with hot nitric acid was observed.
Furthermore, graft polymerization of styrene was retarded by using benzoyl peroxide as an initiator. This fact suggested that free radicals generated by the decomposition of the peroxide prefer to react and combine exclusively with the surface of carbon black. On the basis of these phenomena and the free-radical character of the surface of carbon blacks, a probable mechanism for the graft-polymerization of styrene was presented.
On the other hand, by using α, α'-azobisisobutyronitrile the monomers such as acrylonitrile, vinyl acetate and methacrylates could be easily graft-polymerized onto the surface of furnace blacks in adequate solvent.
Carbon-styrene graft polymer based on furnace black had good dispersion in benzene, toluene or trichloroethylene. However, it had some faults similar to those of styrene polymer. In order to improve these properties, graft polymerizations of styrene with other monomers were also studied.

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[in Japanese]

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