Biosourced Aromatic Derivatives in the Upcycling of Recycled PET: Mellophanic Dianhydride as a Chain Extender

Abstract

The synthesis of mellophanic dianhydride (MEDA) from biosourced 1,2,3,4-benzene tetracarboxylic derivatives and its use as a chain extender for mechanically recycled PET (R-PET) as an alternative to traditional oil-based pyromellitic dianhydride (PMDA) is reported. The rheological tests performed on the R-PET extruded with MEDA have shown similar results to those obtained with PMDA, and dynamic mechanical thermal analysis (DMTA) showed that, in the 90–110 °C range (i.e., the temperature range commonly used for blow molding of bottles), Young’s modulus of R-PET containing MEDA is about 20% higher in comparison to that of pristine R-PET. The advantage of MEDA is that it can be prepared using building blocks obtained from agricultural waste via a sustainable protocol, whereas PMDA is a product of oil-based chemistry.

Chemical recycling of post-consumer PET into high-performance polymer aerogels

“…8,9 In terms of mechanical recycling, almost all recycled PETs are transformed into low/equal-valued PET bottles or fibers, owing to the presence of hydrolysis and pyrolysis side reactions during the remelting process. 10,11 Another approach is chemical recycling of PET at the molecular level, which encompasses the depolymerization of PET waste into virgin monomers or value-added chemicals. 12–15 For example, a library of excellent research studies has upcycled PET waste into specific key intermediates for the synthesis of functional polymers such as polyurethane, 16 polyester, 17–19 polyimine, 20 epoxy, 21 acrylic and alkyd resins, 22 as well as small molecules such as p -xylene, 23 formate salts, 24 and dichloroethane.…”

Cyclodextrin-Based Isocyanate Functional Chain Extender and Its Application in Poly(butylene adipate-co-terephthalate)-Based Agricultural Materials

“…Adding chain extenders is one of the methods to improve the mechanical properties, melt strength, and processability of PBAT. By reacting the active functional groups on the chain extenders with functional groups such as hydroxyl-terminated groups and carboxyl-terminated groups in PBAT macromolecules, the polymer molecular chains are connected by “bridging”, so that the molecular weight of the polymer is significantly increased and the viscosity of the polymer melt is also increased, thereby improving and enhancing its melt strength, mechanical properties, thermal properties, and processability. , Traditional chain extenders, including epoxy chain extenders, − anhydride chain extenders, oxazoline chain extenders, and isocyanate chain extenders, have some shortcomings. For example, epoxy chain extenders (typically styrene and polyethylene) have a polyolefin structure, are not biodegradable, and can easily become small particles of plastic to deposit in the soil after aging, causing severe adverse harm to soil organisms or groundwater .…”