Polyether-epoxy modified polymethylphenylsiloxane emulsions for oil agent in PAN precursors production to improve the hydrophilicity and decrease the hydrodynamic size

Oil agent was a kind of auxiliary agent which played an important role in the processing of carbon fiber. High hydrophilia and low surface tension of polyether-epoxy modified polymethylphenylsiloxane (PEMPS) emulsions used as oil agent had been designed and prepared. Firstly, polyether modified methyldimethoxysilane (PMMS) was synthesized with methoxypolyethylene glycols (MPEG) and (3-isocyanatopropyl)dimethoxymethyl-silane (IPDS). PEMPS were synthesized by introducing PMMS into epoxy modified polymethylphenylsiloxane. With the PMMS content increasing from 0 % to 7 %, the water contact angle of PEMPS decreased from 79.0° to 32.4°. PEMPS emulsions were prepared with PEMPS, surfactants and water. Compared with PEMPS without PMMS, and the hydrodynamic size of PEMPS emulsion containing 7 % PMMS decreased from 310.3 to 159.3 nm, and the surface tension reduced from 22.9 to 20.6 mN/m. In addition, as the interaction between PEMPS and PAN was enhanced, the PEMPS emulsion contact angle on polyacrylonitrile (PAN) film also decreased from 36.2° to 27.8°, indicating that PEMPS emulsions had excellent hydrophilia and proper hydrodynamic size and could be used as PAN spinning oil when the PMMS was 7 %. The surface of PAN precursors coated by diluted PEMPS emulsions was flat, and a significant decrease in heat releasing of precursors during heat treatment could be observed. However, as the solid content was 3 wt%, many agglomerations appeared on the surface of the precursor. Taken together, 1 wt% PEMPS emulsion could repair the grooves on PAN precursors surface and benefit for the spinning process of PAN precursors.