Study of the miscibility and mechanical properties of NBR/HNBR blends

Abstract

In this study, hydrogenated acrylonitrile butadiene rubber (HNBR, ZETPOL-2010L) and nitrile butadiene rubber (NBR, NIPOL-DN4555) were blended at different ratios in a Haake melt blender at 130°C. The HNBR and the NBR were of very similar acrylonitrile content and Mooney viscosity. The melt miscibility and solid-state properties were investigated by rheological, thermal, and mechanical testing and scanning electron microscopy (SEM) techniques. The dynamic viscosity of the blends followed the log-additivity rule, while the flow activation energy closely followed the inverse additivity rule. On the other hand, the storage modulus showed synergistic effects at all compositions, suggesting the presence of emulsion morphology at both ends of the composition range. For the 50/50 HNBR/NBR blend, the SEM micrographs suggest a uniform elongated structure. The thermal analysis showed the presence of two glass transitions, representing the pure components, at all blend ratios, suggesting the absence of segmental miscibility of the blends. The small-strain mechanical properties such as tensile modulus and yield stress followed linear additivity. However, HNBR and HNBR-rich blends were observed to strain harden at a rate higher than that of NBR. Induced crystallization of HNBR was suggested to be the reason for the strain hardening. The different rheological, thermal, and mechanical testing techniques agree in suggesting that the structurally similar HNBR and NBR are not thermodynamically miscible but mechanically compatible.

NR/EPDM elastomeric rubber blend miscibility evaluation by two-level fractional factorial design of experiment

“…The experimental design was generated by using the Design Expert 6.0.10 software implementing the fractional two-level factorial design of 2 5 .Three center points with one replication and no blocks were selected to increase the reliability and the acceptance level of the resulted outcomes. The design generates overall 19 set of sample preparation with parametric combination as per listed in TABLE (2). The real values for each factor coded are listed in the TABLE (3).…”

“…The processing condition like mixing speed, blending period and temperature provide a strong influence on the resulted properties of the blend [2]. Parametric testing of blend preparation has been studied and reported previously by many authors through conventional one parameter at time approach without considering the inter-correlation effects between involving processing factors [5,8,[15][16][17][18][19].…”

“…Currently, various researches on elastomeric rubber blend has been conducted and reported by many authors [1][2][3][4]. Most of the blend like NR/EPDM, NR/NBR, NR/SBR, NR/EVA, SBR/NBR [4], NBR/EVA [1], NBR/HNBR [2] and NR/CR were incompatible and need to be improved accordingly to suit their specific targeted applications.…”

“…Currently, various researches on elastomeric rubber blend has been conducted and reported by many authors [1][2][3][4]. Most of the blend like NR/EPDM, NR/NBR, NR/SBR, NR/EVA, SBR/NBR [4], NBR/EVA [1], NBR/HNBR [2] and NR/CR were incompatible and need to be improved accordingly to suit their specific targeted applications. For the past few years, many researchers have employed natural rubber (NR) and ethylene-propylene-diene-monomer EPDM synthetic rubber for the preparation of elastomeric blends [5][6][7][8][9][10][11][12][13][14].…”

“…Polymer blending can be developed more rapidly with tailored outstanding properties and cost saving than the development of new polymer compound [1][2]. Currently, various researches on elastomeric rubber blend has been conducted and reported by many authors [1][2][3][4].…”