A study of recycled high-density polyethylene with mica addition: influence of mica particle size on wetting behavior, morphological, physical, and chemical properties

This work aimed to study the influence of mica (muscovite type) particle size in recycled highdensity polyethylene (rHDPE) matrix on wetting behavior and morphological, physical, and chemical properties. The r-HDPE/mica composites were compounded with a fixed ratio of 85/15 (weight percentage), varying the mica particle size (45, 75, 100 and 125 mm). The rHDPE and composites were fed into a twin-screw extruder. The materials were characterized regarding particle size, density, hardness, melt-flow index and morphology, variously using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), water contact angle measurements and water absorption measurements. A slight increase in density of composites was observed. The efficacy of the mica to increase the resistance was observed by the hardness results. MFI results suggested alignment of the muscovite particles induced by the extrusion process, corroborating the SEM images. X-ray results indicated the mica contributed to increase the crystallinity of the matrix. For composite materials, the contact angle increased around 17% with mica addition, independently of mica particle size. The absorbed water decreased with mica addition in relation to the matrix and decreased more with larger particle sizes.