Study On Novolac Resins/Montmorillonite Nanocomposites Under Microwave Irradiation

In this paper, the microwave irradiation, which was high heating efficiency, rapid heating rate, low consumed energy and protected environment, had been introduced to the synthesis of phenolic resins (PF) /montmorillorite (MMT) nanocomposites. MMT was previously modified by an ion-exchange reaction between Na+-MMT and alkyl ammonium salt, leading to increase the basal spacing of platelets of MMT. The purpose of this subject was to research not only appropriate microwave irradiation process and the intercalation mechanism, but also excellent structure, physical and chemical property, heat resistance of nanocomposites, and higher strength of coated resins sands.Firstly, on the basis of microwave-assisted process of phenolic resin and summing up abundant experiments, appropriate microwave synthesis process was obtained, which eliminated the phenomenon of ebullition and foam-extravasation.Secondly, the structure of PF/MMT nanocomposites was investigated and analysed by means of XRD and TEM. The analysis indicated that the spacing of MMT was increased and some MMT platelets were exfoliated. The way of MMT-adding, content of MMT and stirring time was influenced the effect of intercalation. When 2wt% MMT mixed round with formaldehyde beforehand for 30 minutes, it was easily obtained exfoliation nanocomposites. Furthermore, the intercalation mechanism was analysed from two aspects of energetics and dynmamics.Thirdly, according to comparing the influence of irradiation methods and the content of MMT on nanocomposites'physical and chemical property, heat resistance, PF/MMT nancomposites synthesised by microwave irrdiration had lower softening point, higher cure rate, further flow distance and better heat resistance compare to which synthesized by conventional method. What's more, under microwave irradiation conditions, the properties of nanocomposites with 2wt% MMT was better.Lastly, from a series of experiments, the best process which is microwave irradiation for 35 minutes, 3wt% MMT and 0.89 F/P was obtained. By this process, the nanocomposites could be obtained which properties were best. Significantly, its MMT platelets were exfoliated and strength of coated resins sands is highest.