Paracril NBR grades are produced by cold and hot polymerization process. The cold process yields linear polymers with good processing characteristics and solubility in polar solvents. The hot polymerization process leads to more branching. Branching in the hot Paracril grades is more developed in the higher viscosity grades. The hot polymers offer improved green strength. Crosslinked Paracril NBR grades are unique in processing and function.
They are produced by chemical crosslinking or conversion branched. The crosslinked grades have varying degrees of reduced mill shrink to as low as 5% versus linear grades of over 35% mill shrink. These grades offer benefits in thermoplastic modification for lower compression set and green strength improvement in thermoset recipes.
Paracril 34PE40, a plasticzer extended grade, contains 50 parts of DOP in a high molecular weight NBR used in the production of low durometer products such as roll covers.