Chain Length Regulation of PA66/PPO-PEO-PPO Multiblock Elastomers: Synthesis, Structure, and Property

Abstract

A series of thermoplastic polyamide elastomers (TPAEs) utilizing polyamide 66 (PA66) as the hard segment and amorphous diamine-sealed poly(oxypropylene)-poly(oxyethylene)-poly(oxypropylene) (PPO-PEO-PPO) with different molecular weight as the soft segment are synthesized through one-step melt polycondensation method. The chemical structure of TPAEs is confirmed by Fourier transform infrared spectroscopy (FT-IR) and hydrogen magnetic resonance spectroscopy (¹H-NMR). Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) results show that short-chain polyetheramine (Jeffamine-ED600) has good compatibility with PA66, which limits crystal growth and greatly reduced crystallinity, can be used as diluent to reduce the melting point of the material. However, the microphase separation of long-chain polyetheramine (Jeffamine-ED900) and PA66 leads to the increase of crystallinity, and the melting temperature does not decrease significantly with the increase of soft segment content. Mechanical properties tests show that all TPAEs exhibit good mechanical properties and excellent energy dissipation, with tensile strength up to 45 MPa and elongation at break up to 630%. The introduction of PEO unit results in the water absorption of TPAEs ranging from 25 to 65%, and the surface resistivity varying between 2.45 × 10⁹ and 1.6 × 10¹⁰ Ω, suggesting the synthesized TPAEs are suitable for use as permanent anti-static materials.