Study on morphology, crystallization behaviors of highly filled maleated polyethylene-layered silicate nanocomposites

The influences of organically modified montmorillonite (MMT) on morphology, crystallization behaviors of maleic anhydride grafted polyethylene (mPE) are investigated by using wide angle X-ray diffraction (WAXD), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), polarized optical microscopy (POM), and dynamic mechanical analysis (DMA). WAXD and TEM results indicate that the molecules of mPE had been inserted into interlayer of the organoclay, and the final morphology of the hybrid changes from exfoliated type to intercalated type gradually with the increasing content of the clay, which is determined by the equilibrium between interfacial interaction of mPE-clay and van der Waals attraction of clay-clay. It is suggested that MMT could affect the crystallization process of mPE in two ways: First, MMT can provide heterogeneous surface and facilitate nucleation step; then, the silicates as diffusion or displacement barriers may restrict the growth step. However, the clay has no significant effects on the total nonisothermal crystallization rate. Otherwise, study on the dynamic mechanical properties show that the storage modulus of the hybrid is around 30% higher than that of the polymer matrix. And the motions of molecular relaxation and conformational transitions both in non-crystalline and crystalline phases are confined by the strong interactions between the polymer and the clay.