Testing has been continued to generate 18 mm crack length in the specimen, and
kilocycles were reported.
Crack initiation was not noticed for the compounds F2, F4, F6 and F8 until 200, 520, 520 and 280
kilocycles, respectively.
Hi/Lo DTDM Monsanto Fatigue-to-failure (
Kilocycles to fail @ 100% strain) Unaged 148 94 80 Overcure(10 x t90 @ 132 107 95 150 [degrees] C) Aged (48 hrs.
Table 2 -- effect of the crosslinking system on fatigue life Compound E F G Sulfur 2.5 1.2 0.33 N-cyclohexyl-2-benzothiazylsulfenamide 0.5 1.8 3.0 Tetramethylthiuram disulfide 2.0 S/A ratio 5.00 0.67 0.07 NRPRA ring fatigue life (0-89% 162 420 50 strain)(
kilocycles)
NR 127 100 12.5 NR-D 114 89.8 14.7 SBR 114 100 15.2 SBR-D 104 91.2 16.6 Sample Relative value NR 100 NR-D 118 SBR 100 SBR-D 109 Table 13 - crack growth Sample
Kilocycles to 8X crack growth NR 20 20 NR-D 15 17.5 SBR 1.0 1.5 SBR-D 1.0 1.0 Table 14 - glass transition Sample Glass transition, [degrees] C Transition range, [degrees] C NR -58.4 5.7 NR-D -59.7 5.5 SBR -47.7 7.6 SBR-D -48.3 8.4