Nylon 12 composite powder prepared by thermally induced phase separation for selective laser sintering

Abstract

A thermally induced phase separation method was successfully developed to prepare spherical composite nylon 12 (PA12)/Nano-silica (Nano-SiO₂) powder. By comparing the performance of pure PA12 and composite PA12 powders, it was found that the introduction of Nano-SiO₂ can improve the sphericity of the composite PA12 powder, with a median particle size of 54–70 μm. Moreover, the presence of Nano-SiO₂ can induce the formation of more α-phase during the crystallization of PA12, and most of Nano-SiO₂ was coated by PA12 molecular chains during the solidification crystallization process, which improved the crystallization temperature and crystallinity of the composite PA12 powder. When the amount of Nano-SiO₂ was 0.3 wt%, the composite PA12 powder had the highest crystallinity, and the powder spreading performance was the best.

Graphical abstract

Mechanism diagram of the reaction between PA12 and Nano-SiO₂. In this figure, it was found that Nano-SiO₂ was treated with silane coupling agent can form siloxane, so that amino groups were grafted to the surface of Nano-SiO₂. The amino groups can react with carboxyl groups in PA12 to form amide bonds, thereby improving the interfacial adhesion between nano silica and PA12 matrix and enhancing their compatibility. Meanwhile, by comparing the microstructure before and after addition, it was found that the addition of Nano-SiO₂ increased the sphericity of the powder, and the powder particle size increased from 55.2 to 68.71 μm.