The toughening mechanism of POM/NBR blends was studied. The results indicate that NBR with high AN content has similar solubility parameter with TPU
and the CN groups or double bond of NBR can capture the formaldehyde or macromolecular free radicals which were produced during POM degradation. This can enhance the compatibility between NBR and POM
thus they can form good alloy. When NBR content reaches 40wt%
the alloy exhibits brittle-ductile transition. The investigation from percolation
rubber-band and quasi-IPN mechanisms indicate that
toughening behavior of NBR to POM and the alloy's B-D transition rule are consistent with POM/TPU system.