High content of spherical nanosilica filled epoxy resin master batch with low viscosity and superior thermomechanical performance

Spherical nanosilica is reckoned as an indispensable filler in electronic encapsulation to improve the thermomechanical performance of epoxy resin matrix. How to achieve higher content and better dispersion of spherical nanosilica in epoxy resin remains a big challenge. Here, Surface-modified spherical nanosilica was prepared on the basis of Stöber method in the presence of binary silane coupling agents as surface modifier. High content of as-modified spherical nanosilica was introduced into bisphenol F epoxy resin (denoted as EP) matrix by one-step liquid-phase method to afford SiO2/EP master batch. The viscosity, thermal stability and dynamic thermo-mechanical properties of SiO2/EP composites with different filler contents derived from SiO2/EP master batch were systematically investigated. Findings indicate that organosilanes grafted onto the surface of silica nanoparticles contribute to improving their compatibility and dispersibility within EP matrix, leading to a relatively low level of viscosity of EP-matrix composites especially under a high nanofiller dosage and improving their dynamic thermomechanical properties and thermal expansion stability as well. Moreover, SiO2/EP master batch made from liquid-phase method exhibits better performance compared with that prepared by physical blending way. It is a facile way to prepare EP master batch with high filler content, low viscosity and superior performance, meanwhile brings processing convenience for application in electronic encapsulation.