High-density polyethylene/recycled HDPE/nanoclay composites using an amine-alcohol modified polyethylene as a compatibilizer

The effect of a high-density polyethylene grafted amine alcohol (HDPE-g-DMAE) as compatibilizer on the mechanical, rheological and morphological characteristics of polyethylene/polyethylene post-consumer recycled blends (HDPE/rHDPE) reinforced with nanoclay was studied. Blends of HDPE with high rHDPE contents, more than 60% (wt) of rHDPE, were evaluated. HDPE bottles were manually separated from municipal solid waste, washed, grinded, and finally compounded at various concentrations with virgin HDPE and nanoclay. The effect of this HDPE-g-DMAE was compared with conventional polyethylene maleic anhydride (HDPE-g-MA) compatibilizer. FTIR characterization confirmed the formation of this HDPE-g-DMAE compatibilizer. The mechanical properties of uncompatibilized blends decreased with increasing rHDPE content, whereas these properties were significantly enhanced when HDPE-g-DMAE was used compared with HDPE-g-MA compatibilizer and with uncompatibilized blends. Scanning electron (SEM) micrographs of the fractured surfaces when using HDPE-g-DMAE showed improvement in the interfacial adhesion and interaction between recycled and virgin polyethylene. The nanocomposites compatibilized with PE-g-DMAE had better clay exfoliation-intercalated structure compared to PE-g-MA-compatibilized nanocomposites. The novelty of this work is based on the use of PE-g-DMAE as a compatibilizer in HDPE/rHDPE/nanoclay composites with improved mechanical properties. This compatibilizer promoted the adhesion between recycled and virgin polymer phases in the blend and increased the interactions between compatibilizer and hydroxyl groups on the clay surface, as well as oxidized groups in the recycled polymer. This indicates that recycled postconsumer HDPE could replace, in larger proportions, part of the virgin HDPE for certain applications with better mechanical performance than uncompatibilized blends. This is an option to bring recycled plastics back into the market and increase the versatility of products manufactured with recycled polymers.