Multiphase morphology control as a robust route to recycling mixed plastic waste

This is the authors' abstract. We don't add key points for this paper.

Plastics are ubiquitous and represent the most intensely used class of materials worldwide. However, they are recycled at notoriously low rates principally because different plastic types must first be identified in the waste stream and separated. Due to their mutual immiscibility, they are largely recycled as a quasi-pure plastic. Here we demonstrate an approach to directly recycle this very problematic mixed plastic waste (MPW) by combining it with a highly continuous carrier system of recycled polypropylene (rPP) and recycled polyethylene (rPE). Through an effective control of the rPP/rPE interface, the mixed plastic waste segregates during one-step melt processing in a stable fashion, according to spreading theory. The MPW components segregate into the rPP phase except for the polyethylene portion which goes into the rPE phase, as evidenced by AFM-IR. This controlled segregation of MPW allows the mechanical integrity to be borne by the principal co-continuous rPP/rPE interface. The final rPP/rPE/MPW material, containing 30% mixed plastic waste, exhibits properties, including impact strength, that are very similar to recycled polypropylene and, critically, can be further recycled multiple times with very little property loss.