(1) Fatigue (by disk fatigue tester) in nylon 6 tire cords at elevated temperatures was measured. Infrared absorption spectra of nylon 6 films at elevated temperatures were also measured, and a change of the hydrogen-bonding force was estimated from the shift of the N-H absorption band.
It was concluded from these measurements that the increase of fatigue in nylon 6 tire cords at elevated temperatures was correlated with the decrease of hydrogen-bonding force which constituted a fine structure in nylon 6.
(2) Fatigue in tire cords at room temperature.
a : Fatigues in nylon 6 and polyester tire cords which had been heat treated at higher temperatures were greater than those of the cords which had been heat treated at lower temperatures.
b : Fatigues in nylon 6 tire cords which had lower twists were greater than those of the cords which had higher twists.

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The thermal stability of the polymers prepared from sulfur-containing aldehydes (SA), R'SCH (R) CH₂ CHO (R = H or CH₃, R' = alkyl, allyl and aromatic groups) was studied. Thermal stability tests were carried out by the method of measurement of weight loss at the constant temperature (100 or 150 °C) under air or reduced presure (2 mmHg). When the polymers of SA were compared with that of aliphatic aldehydes such as acetaldehyde, n-and i-butyraldehydes, a striking difference in the thermal stability was noted. The latter were very unstable, as well known, while the former showed fairly good stability.
On the other hand, the copolymers of SA with aliphatic aldehydes were very more stable than the homopolymers of these aliphatic aldehydes, but less stable than that of SA. The thermal stability of the copolymers depended upon the content of SA-composition in copolymer.
Moreover, when the cyclic trimers (1, 3, 5-trisubstituted trioxanes) of SA were added to polyacetaldehyde, an enhanced stability of polyacetaldehyde was observed. The role of sulfide group for stabilization was discussed.

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In the preceding paper, attention was drawn to the fact that some oligomers of sulfur-containing aldehyde (SA, R'SCH (R) CH₂CHO) showed the thermal stabilization effect on some polymers. In order to contribute to the detail examination of their thermal stabilization ability, synthesis of many SA and their oligomers such as cyclic trimers and Tischchenko's esters (dimer) was tried.
SA was synthesized by the addition of 5 kinds of higher alkyl and aromatic mercaptans to acrolein or crotonaldehyde in the presence of basic catalyst in a similar manner to the case of lower mercaptans. Cyclic trimers (1, 3, 5-trisubstituted trioxanes) were synthesized with good yield by the use of BF₃·Et₂O as catalyst in toluene at 010°C. Esters (R'SCH (R) CH₂CH₂OC (O) CH₂CH (R) SR') were also easily synthesized by so-called Tischchenko's reaction with AlEt₃ or Al (Oi-Pr)₃ as catalyst in toluene at 010°C.
These derivatives were confirmed by IR and NMR spectra, MW determination and ultimate analysis, and refractive index. Most of these compounds were new compounds.

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The oligomers of sulfur-containing aldehyde (SA) such as cyclic trimers and Tischchenko-esters were added to non-vulcanized rubbers (polypropylene oxide, NR and SBR), and the thermal stabilization effect was studied with TGA and DTA. The stabilization effect was evaluated by measurement of the extent of shift to high temperature side of temperature starting weight loss on TGA-thermogram and the temperature starting strong exothermic phenomenon on DTA-thermogram. When the SA-oligomers were added to rubbers, in all cases the extent of shift was larger than that of control samples. The Fact Seems to Indicate that SA-oligomers retarded the thermal oxidative degradation of rubbers. Commercial sulfur-containing stabilizer, dilauryl thiodipropionate (DLTP), also showed a similar shift. In this case the extent of shift was smaller than or equivalent to that of SA-oligomers. Any regular relationship between the chemical structure of SA-oligomers and the extent of shift could not be found from above experiments.

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The distribution of silica and trimethylolpropane trimethacrylate (TMPMA) in a blend of BR/IR was studied by electron microscopy. When thin sections of the blend were treated with the vapor of osmium tetroxide, the rubber components in the blend were stained and fixed. This method was found to enhance the contrast of the components in the order of TMPMA > BR > IR. When the blend of BR/IR is loaded with silica, the filler was distributed preferentially in the IR phase. The IR masterbatch method gave a more uniform dispersion of silica in the IR phase. In the case of BR masterbatch, the agglomeration of silica located in both BR phase and the phase boundary. When silica and TMPMA were mixed with the blend of BR/IR, the TMPMA was dispersed in small globules with the diameter of about 100 Å throughout the matrix, especially in the BR phase with high density. The agglomerations of silica surrounded with TMPMA migrated to the BR phase during mixing.

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