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| To improve the compatibility and dispersion stability of kaolin (K) in epoxy matrix, oligomeric epoxy was employed to modify K by a simple dry-method. After modification, epoxy resin was successfully grafted on the surface of K through chemical bonds, and the grafting rate was as high as 21.65 wt%. The contact angle of EP-K (101.28 ) was much higher than that of the pristine K (12.65 ). It was proved that the hydrophobic nature of organically modified K was improved significantly. Compared with the raw K, SEM demonstrated that the EP-K exhibited a homogeneous dispersion in organic solvent or in epoxy matrix. The EP-K /EP composites fabricated by solvent-free method possessed improved thermal stability and significant improvement on storage modulus. Due to the excellent insulation of K and the homogeneous dispersion, the dielectric constant of composites was lower than neat epoxy with the EP-K≤30 wt%. Compared with the non-modified K composite, the modification of K on permittivity of the composite was encouraged. However, all of the EP-K/EP composites still maintained a good insulating property. Hence the material developed in this work could be explored for a possible high performance and industrial application as microelectronic encapsulation material. |
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| Keywords:polymer/inorganic-particles composite; kaolin; epoxy; surface-modification |
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