Influence of electrolytes on thermal expansion microcapsules

Thermal expansion microcapsules were prepared by using acrylonitrile and methyl methacrylate as polymerization monomer and isooctane as the blowing agent. The structure, composition, appearance, and thermal expansion properties of microcapsules were analyzed by SEM, FTIR, TG, DSC, and TEM. The cell structure and surface quality of PP foaming composites were characterized by SEM, optical microscopy, and gloss meter. Results show that sodium chloride in the aqueous solution can significantly improve the appearance of microcapsules. At 15.1 and 19.1 wt.% sodium chloride, the appearance of microcapsules was regular. At 19.1 wt.% sodium chloride, the thermal expansion microcapsules were coated with 25.0 wt.% of the blowing agent. The microcapsules exhibit an expansion temperature of 201 °C and can remain stable after expansion. Moreover, the microcapsule shell of the data (thickest part − thinnest part)/(core diameter) decreased to approximately 0.05. The glossiness of PP/(T-5) increased to 65.6. The surface of PP/microcapsule foaming composite is smoother than that of the PP/AC foaming composites, and the pores of thermal expansion microcapsules are difficult to deform during processing.