Study On Compatibilization Effects Of Montmorillonite On Immiscible HDPE/PS Blends

Rigid inorganic filler has been used as a reinforecing agent in polymer materials for a long time. Recently, the possibility that using filler as a compatibilizer for immiscible polymer blend was suggested. In this paper, we reported the apparent compatibilization effects of montmorillonite(MMT) on the immiscible high density polyethylene (HDPE)/polystyrene(PS) blends, and compatibilized blends of HDPE/sulfonic PS(SPS), HDPE grafted with acrylic acid(PEAA)/PS, and PEAA/SPS. X-ray diffraction(XRD) and transmission electron microscopy(TEM) results revealed that the dispersion of MMT in compatibilized blends was better than in immiscible blends. Scanning electron microscopy (SEM) results revealed that in PEAA/PS and PEAA/SPS blend the size of the dispersed PS phase decreased with increasing clay content and the dispersion of PS phase become better, while in HDPE/PS and HDPE/SPS blend, the addition of MMT did not affect the size and dispersion of PS phase. Consequently, the mechanical properties of PEAA/PS/MMT and PEAA/SPS/MMT blend were better than that of HDPE/PS and HDPE/SPS composites with the same MMT content. Differential scanning calorimeter(DSC) results show that the melting temperature(Tm) of HDPE slightly increased and melting endotherms(â–³H) decreased when MMT was added into PEAA/PS and PEAA/SPS blends, indicating MMT improved the compatibility of these two kinds of blends. Positron annihilation lifetime spectroscopy(PALS) results revealed that when the polarity of matrix increased, the free-volume size and concentration decreased, and the interfacial area increased, suggesting the compatibility of system increased.All these results show that MMT can improve the compatibility of blends whose main composition is PEAA. Moreover, the effect is the best on PEAA/SPS blend than other three kinds of blends. And in HDPE/SPS and HDPE/PS blends, MMT did not affect the compatibility. In a word, when the MMT was added into a blend and affect the compatibility of blends, whether the main composition is polar is very important. If the main composition is polar, the compatibilization effect of MMT on blends is obvious. In comparison, if the main composition is unpolar, the effect is undistinct. And, the polarityof dispersed composition only affect the dispersion of MMT in matrix. Considered the good dispersion of MMT in polar matrix and agglomeration in unpolar matrix, the mechanism of the compatibility effect of MMT is that the exfoliated MMT prevent the congregation of the dispersed phase.