Abstract
Composites based on recycled high-density polyethylene (rHDPE) and muscovite mica, with different rHDE/mica ratios (100/0, 95/5, 90/10, 85/15 and 80/20, weight percentage) were prepared in an internal mixer with roller-type rotors at temperature of 170 ºC for 10 minutes. The materials obtained were characterized by tests of density, Shore hardness D and melt-flow index, along with infrared spectroscopy, thermogravimetry, differential scanning calorimetry and scanning electron microscopy. The hardness analysis confirmed the action of mica as a reinforcing load in the matrix, but this effect stabilized at around 15%. The TG analysis showed that the 85/15 composite presented slightly better performance than the 80/20, indicating that mica, up to 15%, caused disorganization of the polymer structure instead of reinforcing it. The DSC results revealed that the composites had slightly lower melting temperatures than the matrix. The FTIR spectrum indicated there was no chemical interaction between the rHDPE and mica.
Highlights
Traditional plastics do not degrade in the environment
There was relatively good adhesion between the filler and matrix, with few occurrences of small cavities around individual particles. This good adhesion of rHDP/ mica was not observed in the virgin HDPE/mica composites studied by Lapčík et al.[7]
The good adhesion of the recycled high-density polyethylene (rHDPE)/mica composites studied in this work can be attributed to the presence of additives in the plastic lumber[3]
Summary
Traditional plastics do not degrade in the environment. In particular, polymers require hundreds of years to degrade under normal environmental conditions. Polyethylene (83%), polypropylene (7%) and polyvinyl chloride (9%) are the main polymer matrices used in the manufacture of plastic lumber composites These products have gained market share in various applications (decks, railings and automotive parts) due to their good mechanical properties, low costs and renewability[3,4,5]. Gerardo et al studied the influence of mica (muscovite type) particle size (less than 45, 75, 100 and 125 μm) in a recycled high-density polyethylene (rHDPE) matrix on the wetting behavior and morphological, physical, and chemical properties. The novelty of this work is to analyze the sustainable recycling of high-density polyethylene (rHDPE), in particular the improvement of its thermal and mechanical properties by adding mica (muscovite type), a mineral with low value, with fixed particle size (less than 100 μm), without use of a compatibilizing agent. The composite materials were characterized by scanning electron microscopy (SEM), thermogravimetry/ derivative thermogravimetry analysis (TG/DTG) and differential scanning calorimetry (DSC) as well as by determination of density, hardness and melt-flow index (MFI)
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