Purification And Modification Of Montmorillonite And The Curing Of Benzoxazine/Montmorillonite Hybrid

In this paper, the modification of montmorillonite by several organic modifiers through cation exchange reaction is investigated. The organic montmorrillonite with different properties and structure is synthesized and characterized by XRD,IR,TG. As a result, the layer distant of montmorillonite modified by the long chain alkyl ammonium salt is larger than that of others and the long chain stay in the layer in the way of single-olefin kind. Furthermore, the montmorillonite could be modified by several organic agent at the same time.Ion-dipole method, a new process is used from which the montmorillonite is purified and modified in on step. After the process, the montmorillonite is transferred from the calcium kind to the sodium kind and a higher Cation Exchange Capacity (CEC) is obtained, which is advantageous to the organic modification through cation exchange reaction.The curing of BZ/MEL-MMT hybrid has been studied by isothermal and dynamic differential scanning calorimetry (DSC) and torsional braid analysis (TBA). As a result, the curing reaction could be initiate in the lower temperature by adding the modified montmonillonite into the benzoxazine resin and the percentage of montmorillonite has little effect on the iniatial curing temperature. The activation energy and the order of the reaction are obtained by using the Freeman-Carroll and Kissinger, which would keep the same when the scanning rate is changed. Comparing the curing behavior of BZ,BZ/C18-MMT and BZ/MEL-MMT system in different scanning rate, the catalysis curing due to the ammonium salt and the thermal curing have been found in the BZ/C18-MMT and BZ/MEL-MMT hybrid. The ration of these two kinds of curing behavior could be different depending on the scanning rate. In the same rate, the percentage of thermal curing is higher in the BZ/MEL-MMT hybrid than that in the BZ/C18-MMT hybrid. During the cure, the phase of hybrids changes from liquid to glass, which is accompanied by gelation and vitrification phenomena.In addition, the flammability of PBZ and PBZ/MEL-MMT hybrid is compared. The result is not as good as expectation. The reason is that the curing technique and dispersion of montmorillonite in polybenzoxazine will affect the flammability of materials. There is still a large work to do.