Polymer Blends with Hydrogenated Nitrile-Butadiene Rubber and with an Ionomer of Hydrogenated Carboxylic Styrene-Butadiene Rubber

Abstract

Hydrogenated nitrile-butadiene rubber (HNBR) and hydrogenated carboxylic styrene-butadiene rubber (HXSBR) were obtained from rubber latex via the diimide process without pressurized hydrogen. The ionomer of HXSBR was prepared via neutralization of HXSBR with a metallic ion. HNBR was melt-blended with polyethylene (PE) or poly(vinyl chloride) (PVC) and the potassium ionomer of HXSBR was blended with PE. Study of mechanical properties of the blends showed that when HNBR was higher than 40% of the blends, both blends behaved as thermoplastic elastomers. The HNBR/PE blend seems much better than NBR/PE blend with respect to mechanical properties, probably because of the presence of polyethylene segments in HNBR that enhanced the compatibility between HNBR and PE. After thermal aging at 150°C for 80 hr, the blends of HNBR/PE retained most of the mechanical properties, whereas the specimens of NBR/PE blend became twisted. However, the difference between HNBR/PVC and NBR/PVC blends was somewhat less, probably because the two components of both blends are miscible, and self-crosslinking occurred during thermal aging. Scanning electron microscopy and differential scanning calorimetry were used to characterize the HNBR/PE blends. When the potassium ionomer of HXSBR was melt-blended with PE, the blends exhibited a synergistic behavior with respect to the tensile strength probably because of the formation of a thermoplastic interpenetrating polymer network through the crystalline domains of PE and the ionic domains of the ionomer.