Functionalized Kaolin And Hollow Glass Microspheres As Reinforcement For Polymer Composites

Epoxy resin as one of the most important thermosetting engineering polymers,have a variety of applications in the aerospace,semiconductor encapsulation,adhesives and coatings owing to its unique tensile strength,superior insulation behavior,good adhesiveness and chemical resistance,since its first commercial production.Ascribed to its low dielectric constant,epoxy was selected as the preferred material in the field of electric packaging.But along with the continuous renewal of electronic products,pure epoxy resin can't achieve the requirements of the modern electronic equipment.Kaolin(K)and hollow glass microspheres(HGM)have excellent electrical insulation property.So,they were chosen to modify epoxy resin respectively,to get more effective performance of epoxy resin composites.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.Through the solvent modification,epoxy resin was grafted on the surface of kaolin,then kaolin was filled into epoxy matrix to enhance and improve the mechanical properties and electrical insulation properties of PVC composites.When the content of EP-K was 10 wt%,the volume resistivity of composites at 20? increased by 50.3% than that of pure PVC.With the filling of EP-K,the comprehensive performance of PVC composites was more excellent.After surface modification,homogeneous dispersion and strong interfacial interaction between HGM and epoxy were obtained,thus HGM was used as reinforcement to improve the mechanical properties of epoxy composites.Due to the excellent insulting property of HGM,the dielectric constant of all obtained composites were lower than that of pure epoxy.When the content of modified HGM is 6 wt %,dielectric constant decreased to the lowest value,about 2.7.It is reasonable to state that the addition of HGM into epoxy resin optimized the insulating property of composites.