Effect of modifying EPDM on the crosslink distribution in NR/EPDM blends

Brown, P. S.; Tinker, A. J.

Effect of modifying EPDM on the crosslink distribution in NR/EPDM blends

1996

Brown, P. S. | Tinker, A. J.

The swollen-state FT-NMR spectroscopic method of blend analysis has been applied to blends of NR with two different EPDMs and chemically modified versions of these EPDMs. The crosslink densities in the EPDM phases of the blends olefin with unmodified EPDM are very low, approximately 10molm-3. The presence of the chemical modification to the EPDM has a dramatic effect on crosslinking in the EPDM phase, more than doubling it, but only a minor one on that in the NR phase. The overall + crosslink density in the blend is, therefore, increased. Despite these changes there remains a large imbalance in the crosslink distribution in favour of the NR phase in both modified blends, yet the reported physical properties are good. This suggests + that there may be a threshold value for the crosslink density in the EPDM phase for a blend to achieve good physical properties.

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