The study was undertaken to evaluate the effect of the filler (kaolin) modification with silane coupling agents on the properties of the polyethylene (HDPE Hostalen ACP 5831) composites. Powder mineral fillers are added to polymers to modify the properties of the latter and to reduce the cost of their production. A very important factor is the filler dispersion in the polymer matrix. Kaolin modified with 3-methacryloxypropyltrimethoxysilane and pure kaolin were characterised by surface area, pore size, water absorbing capacity, paraffin oil absorbing capacity, bulk density, scanning electron microscopy observations and X-ray diffraction measurements. Their performance was characterised by determination of the mechanical resistance upon static stretching and tearing, and their structure was observed in scanning electron microscopy images. The results were compared to those obtained for the composites with unmodified filler and pure HDPE.

This paper shows the results of using the modified kaolin by silane coupling agents in HDPE composite and the effect of surface modifications of fillers on the properties of polyethylene composites. In the first stage pure and modified kaolin was subjected to a number of tests in order to determine the backfill density, water and paraffin oil absorbability, the surface area and pore volume, the morphology of their grains, thermal analysis and the FT-IR spectroscopy. In the second stage the composites, which were moulded into the samples that could be subjected to further tests, were produced. The samples were characterised by the determination of the hardness according to Shore, the elasticity modulus, the tensile strength and tearing strength. The modification of the kaolin surface has resulted in a substantial improvement of the strength parameters of the obtained polyethylene composites.

The effect of modification of montmorillonite (with 3-aminopropyltrimethoxysilane or hexadecyltrimethylammonium chloride) on the mechanical properties of the composites based on HDPE Hostalen ACP 5831 with the modified montmorillonite as filler, was studied. The structures of the fillers and nanocomposites were characterised by the scanning electron microscopy and X-ray diffraction study. The effect of the filler modification on the mechanical parameters of the nanocomposites and their structure was assessed on the basis of determination of the mechanical resistance, elongation at maximum tearing stress, bending strength, deformation at the maximum force and elasticity modulus on bending (three-point bending strength).