Surface energy induce asymmetric phase distribution in films of a binary polymeric blend

The phase morphology of blends of low density polyethylene (PE) with low molecular weight copolyamide (CPA) was investigated in films having 50-100 mm thickness. Films were prepared by compression moulding between two surfaces with different polarity, namely teflon and aluminium sheets, in a parallel plate heating press. The film surface characterization and surface energy deduction were performed by FT-IR/ATR spectroscopy and contact angle measurements, respectively. Moreover, the morphology and phase distribution were investigated by scanning electron microscopy both on the surfaces and on the cryogenic section of the films. The copolyamide resulted to be the dispersed phase in all compositions (90/10, 95/5, 97.5/2.5 and 99/1 PE/CPA) and the shape, dimension and distribution of the domains depending on temperature, pressure, time and nature of the surfaces used during the compression stage. The experimental evidences were discussed with respect to the different surface energies of the type of moulding material during the film preparation and related compatibility of the components