Abstract: A high modulus composition based on a mixture of a hydrogenated acrylonitrile butadiene rubber which has been modified with either zinc methacrylate or a combination of zinc oxide and methacrylic acid and an unmodified hydrogenated acrylonitrile butadiene rubber for use in high load-bearing synchronous drive belts and belts made therewith.

Abstract: The present invention relates to a hydrophilic nitrile rubber which is particularly useful in making photopolymer formulations for printing plates utilized in flexographic printing applications. The hydrophilic nitrile rubber of this invention is made by treating a standard carboxylated nitrile rubber with a sulfur trioxide/dimethylformamide complex. This invention more specifically discloses a process for preparing a hydrophilic nitrile rubber composition which is particularly useful in making photopolymer formulations for printing plates, said process comprising the steps of (1) reacting a carboxylated nitrile rubber with a complex of sulfur trioxide and dimethylformamide to produce a nitrile rubber containing sulfonated carboxyl groups and (2) reacting the nitrile rubber containing sulfonated carboxyl groups with a salt selected from the group consisting of sodium hydroxide and potassium hydroxide to produce the hydrophilic nitrile rubber.