Application of hygrothermally decomposed polyurethane in rubber recipes part 1: Natural rubber (NR) and nitrile rubber (NBR) stocks

In this work hygrothermally decomposed crosslinked polyurethane (PUR) was m ixed up to 20 phr in standard natural (NR) and nitrile rubber (NBR) recipes . Their curing (CV system) and mechanical behavior were studied. It was fou nd that addition of decomposed PUR resulted in faster cure and reduced Moon ey viscosity in NR compounds. The effect was however not prominent for a st andard NBR recipe. Increasing PUR content in NR compounds resulted in a mod erate increase in tensile strength, elongation at break, modulus at 300 % e longation and tear strength. The opposite tendency was observed, however, f or the NBR stocks. Both NR and NBR compounds showed an increase in compress ion set and abrasion with increasing PUR content.