| Epoxy/organic-montmorillonite nanocomposites were prepared with different organic-montmorillonite and content of montmorillonite by diglycidyl ether of bisphenol A, montmorillonite as inorganic filler, octadecyl trimethyl ammonium chloride and silane coupling agent KH550 as modifying agent, methylhexahydrophthalic anhydride as curing agent. Parameters of the curing process were optimized by the theory of orthogonal experimental design.Chemical composition of different organic-montmorillonite was analyzed by Fourier Transition Infrared(FTIR). The mechanism of interaction effect between different organic modifying agent and montmorillonite was studied. The temperature properties of resistivity of composites was measured by Megger. The temperature dependence of composites dielectric spectrum was verified by using a Schering bridge. The frequency dependence of composites dielectric spectrum was verified by using novocontrol alpha-a. The effects on composites'electric properties caused by different organic-montmorillonite and contents of montmorillonite have been discussed.Whether octadecyl ammonium chloride or the coupling agent KH550, they can interact with the montmorillonite both, through analyzing FTIR spectrum of organic-montmorillonite. The character of the montmorillonite changed from hydrophilic to hydrophobic. The test results of the composite indicated that, inclusion of K-MMT and O-MMT into epoxy matrix can reduce permittivity and dissipation factor. The permittivity and dissipation factor of K-MMT/EP composites respectively reduced 5% and 35%, the permittivity and dissipation factor of O-MMT/EP composites respectively reduced 16% and 41%, when testing temperature is 160℃. It can be confirmed that epoxy improved by organic-montmorillonite is provided with better heat resistance property than those of pure epoxy. As for O-MMT/EP composites, the permittivity and dissipation factor of composites that contains 5wt% O-MMT is lowest. For instance, the permittivity reduced 18% and the dissipation factor reduced 42% than pure epoxy, when it is room temperature and power frequency. For further investigation on this appearance, relaxation time and distribution were tested on epoxy and epoxy/montmorillonite nanocomposites. The results showed that: relaxation time of epoxy/montmorillonite nanocomposites were the longest and distributed parameter is the smallest, when the montmorillonite content was 5wt%. In addition, compare with relaxation time and conductivity of composites, we found they have existed direct proportion relationship. |
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