Reinforcement efficiency from weak polymer chain interaction between polyamide and hydrogenated nitrile: A comparative study of polyamide 1212 and polyamide 6

In polymer blends , the macroscopic properties are directly affected by the phase separation morphology. For polyamide/hydrogenated nitrile blends, the factors that influence the relationship between the reinforcement effect and the phase separation morphology are unclear. In this study, the reinforcing effects of polyamide 6 (short-chain polyamide) and polyamide 1212 (long-chain polyamide) in the hydrogenated nitrile (HNBR) matrix were comparatively analyzed. Deep analysis was performed on the mechanical properties, oil resistance, dynamic mechanical properties, and tribology properties of the blends. Results show that the interaction of polyamide 6 (PA6) with the HNBR chains was stronger than that of polyamide 1212 (PA1212). However, PA1212 exhibited a better enhancement effect than PA6 on the matrix. In the 20 wt% PA1212/HNBR blend, no friction marks were observed on the surface of the specimen. This phenomenon can be attributed to the synergistic effect of the uniformly dispersed particle and fibrous phase of PA1212 induced by the HNBR matrix. The formation of this special structure was closely related to the weaker physical interaction between two different phases (i.e., lower T g , smaller wavenumber shift, and weaker heterogeneous nucleation effect). This result was creative and could provide theoretical and experimental support for the regulation of the phase separation morphology of PA/HNBR blends with high performance.