Sustainable Composites Based on Recycled High-density Polyethylene/mica

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.

Composites Based on Post-Industrial Wood Plastic Waste and Ultrasonic Treated Muscovite

“…The OH stretching vibrations, occurred between the 3750-3550 cm -1 region. The vibrations of the mica group minerals can be observed in the 1200-700 cm -1 region (Si-O stretching) as pointed by Ismail et al 18 , Almeida et al 7 and Gerardo et al 4 . Vibrations of the interlayer cations usually are located in the range of 400-50 cm -1 , so it is not possible to see them in our spectra.…”

“…The wood plastic waste used was provided by Companhia Municipal de Limpeza Urbana (Comlurb, the municipal sanitation agency in the city of Rio de Janeiro). According to data obtained from previous works, this material is composed mainly of high-density polyethylene (HDPE), other polymers in smaller quantities (i.e., PE, EVA) and additives 4,7 . The process to prepare the material for use in the composite initially consisted of manual separation to eliminate undesirable coarse residues, followed by manual cutting into smaller sizes to allow insertion into the feeder of the single screw extruder 7 .…”

“…This material has applications similar to those of common wood, so it can be nailed, screwed, riveted or glued. However, because it is manufactured primarily from polyolefins, its thermal and mechanical resistance is not ideal, and warping and discoloration during use are common, mainly due to exposure to the sun's heat and other inclement weather conditions 4,7 .…”

“…However, mining of clay minerals in this region is mainly artisanal, which typically is carried out without precautions against environmental pollution and also means the clay has low added value. On the other hand, these minerals' natural origin means they can be processed without use of potentially polluting chemicals 4,7 .…”

“…Almeida et al 7 studied the influence of muscovite content (0 -20%) on wood plastic properties. An improvement in properties was observed, mainly hardness, density and melt flow index (MFI), with mica content up to 15%, but low efficiency of mineral dispersion and its interaction with the matrix was observed, suggesting the need to use compatibilizing agents.…”