For compounds A to I (tables 2 and 3), there are several clear trends. In general, compounds A to E (based on crosslinked NBR) display higher tensile and modulus, and also better compression set and abrasion resistance than compounds F to I (based on linear NBR polymer modification). The use of higher BAN type NBR results in better resistance to oil in the IRM903 aging test after 70 hours at 100°C. It should be noted that compound A is based on a branched crosslinked type and compound D is based on a low level of chemical crosslinking