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A diversity of chemicals are intentionally added to plastics to enhance their properties and aid in manufacture. Yet, the accumulated chemical composition of these materials is essentially unknown even to those within the supply chain, let alone to consumers or recyclers. Recent legislated and voluntary commitments to increase recycled content in plastic products highlight the practical challenges wrought by these chemical mixtures, amid growing public concern about the impacts of plastic-associated chemicals on environmental and human health. In this Perspective, we offer guidance for plastics manufacturers to collaborate across sectors and critically assess their use of added chemicals. The ultimate goal is to use fewer and better additives to promote a circular plastics economy with minimal risk to humans and the environment. 

This study focuses on creating an optimal grafting compatibilizer for blends of polypropylene carbonate (PPC) and polybutylene succinate (PBS). PPC and PBS were blended separately with different amounts of maleic anhydride (MAH) and with and without dicumyl peroxide (DCP) to aid the free‐radical grafting. Titration analysis evidenced that MAH reacted with the polymers terminal groups and backbones using free‐radical functionalization. Thermogravimetric analysis (TGA) and gas permeation chromatography (GPC) results demonstrated how the thermal stability of PPC improves with the addition of MAH. Proton NMR proved that, in both PPC and PBS formulations, ring‐opening reactions and grafting of the intact MAH ring occur, as well as interchain grafting producing network structures. The rheological analysis showed that small quantities of MAH and DCP increase the viscosity of the resins. The compatibilizer that was determined to be most reactive and stable of all the formulations analyzed was PPC with 2% MAH and DCP and its effect in the morphology of PPC‐PBS blends was proven successful by a reduction of the PPC droplet size. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2019,136, 47553.

 

The functionalization of poly(propylene carbonate) (PPC) by means of both free radical and esterification grafting of Maleic anhydride (MAH) aided by a peroxide is simulated by means of a kinetic model. The amount of MAH grafted (A_g) measured from batch mixer trials shows good agreement with the simulated results. Sensitivity analysis of the different rate constants shows that peroxide decomposition is the factor that drives the reaction, meaning that the choice of initiator affects greatly the reaction conversion. The next most dominant reaction is the chain ends esterification. There is a competing effect between chain initiation and side reactions, however, chain initiation is slightly more dominant than the latter. It is also found that higher content of peroxide induces higherA_g. The amount of MAH has a lower impact onA_gat low peroxide concentration; however, it becomes more influential in the presence of more peroxide.

 

The potential of exchange reactions using titanium butoxide (TBT) as catalyst for the compatibilization of poly(butylene succinate) and poly(propylene carbonate) was explored, and the effects of high speed reactive extrusion on the ester–carbonate exchange reaction were studied. The feasibility of this functionalization route was contrasted to the free radical grafting (FRG) type using maleic anhydride and a peroxide. First, batch mixing and solution blending were conducted to determine the suitable amount of catalyst for blends of this kind. Then, blends at different screw speeds, reaching 1,000 rpm were compounded with catalyst on a twin‐screw extruder. Spectroscopy techniques corroborated the formation of block and graft copolymers on the TBT and FRG samples, respectively. Both compatibilization paths produce a positive change in the mechanical properties of the system that was accompanied by a finer droplet size and better interfacial interaction. Specifically, the high‐speed runs using a catalyst demonstrated a 177% improvement of the strain at break, proving that the high mechanical energy imparted impacts positively the mixing performance. POLYM. ENG. SCI., 59:1986–1998, 2019. © 2019 Society of Plastics Engineers