The effect of olefin block copolymer and organoclays in recycled HDPE/PP nanocomposites

The circular economy promotes the recycling of plastics to develop new materials and products. The blends of immiscible plastics increase the availability of raw materials. This research aims to process and relate the morphology, rheological and thermo-mechanical properties of recycled high density polyethylene (rHDPE) and recycled polypropylene (rPP) modified by the addition of commercial organoclays (OMMT) and olefin block copolymer (OBC) compatibilizer. Given amounts of post-consumer blends of rHDPE coming from packing and rPP from lids were mixed in a torque rheometer. Mixes of virgin HDPE and PP in percentages of 0, 20, 40, 60, 80, 100 wt% were prepared to determine the concentration of these plastics in the blends. The corresponding DSC calibration curve of enthalpy of fusion versus weight percent was obtained. The resultant mixture of rHDPE/rPP (-83 wt%/-15 wt %) was melted with two organoclays (Cloisites20A and Cloisite 93A) (3 wt%) and with or without the presence of OBC (D5541) (5 wt%). Intercalated structures were observed in both clay nanocomposites, but Cloisite 20A showed greater basal spacing than those of Cloisite 93A. It was found that the organoclays and the OBC decreased the crystallinity on rHDPE and rPP. Rheological measurements using a plate-plate rheometer showed a viscosity increase of blends in the presence of both organoclays, at low shear rates (- 10 s−1), being the Cloisite 20A the one that showed the highest values. On the other side, the OBC decreased the viscosity in all composite blends, at higher shear rates (60-100 s−1). Both organoclays increased the stiffness of the rHDPE/rPP, but the OBC in conjunction with the organoclays declined the stiffness. The impact resistance was improved in the presence of the organoclays and the OBC. Based on these results, it can be concluded that the two organoclays used in this study can be used as compatibilizers for rHDPE/ rPP blends.The circular economy promotes the recycling of plastics to develop new materials and products. The blends of immiscible plastics increase the availability of raw materials. This research aims to process and relate the morphology, rheological and thermo-mechanical properties of recycled high density polyethylene (rHDPE) and recycled polypropylene (rPP) modified by the addition of commercial organoclays (OMMT) and olefin block copolymer (OBC) compatibilizer. Given amounts of post-consumer blends of rHDPE coming from packing and rPP from lids were mixed in a torque rheometer. Mixes of virgin HDPE and PP in percentages of 0, 20, 40, 60, 80, 100 wt% were prepared to determine the concentration of these plastics in the blends. The corresponding DSC calibration curve of enthalpy of fusion versus weight percent was obtained. The resultant mixture of rHDPE/rPP (-83 wt%/-15 wt %) was melted with two organoclays (Cloisites20A and Cloisite 93A) (3 wt%) and with or without the presence of OBC (D5541) (5 wt%). Intercal...