Introduction of new methods for increasing the level of recycled PET plastics

The Global Plastics Environmental Conference of the SPE (American Plastics Engineering Association) held in Detroit, USA, provided some new developments, including new types of additives that increase the level of recycled PET resin.

The new additive introduced at the SPE meeting was Clariant Masterbatch's CESA-Extend series of reactive additive, which has the effect of long-chain branching of the PET molecule and can improve PET recycling without reactor solid-phase reaction. With the intrinsic viscosity and the addition of the CESA-Extend chain extender, the molecular weight of PET is increased to the equivalent molecular weight of the new PET resin without sacrificing the mechanical properties, thermal properties and crystallinity. In addition, CESA-Extend is easy to use. General PET chain extension must be pre-dried by heating under high vacuum for several hours, sometimes it can not control the branching reaction to produce gel, but now add CESA-Extend by twin screw extruder. Without pre-drying under high vacuum, only a small amount of gel is produced.

Another role and advantage of Clariant's new chain extender is to improve the compatibility of recycled PET with other polyesters, polycarbonates, and nylons. This active additive is provided by Johson Polymers LLC of Wisconsin, USA. Functional acrylic oligomers, the company and Clariant co-owned technology patents of the product. According to reports, CESA-Extend can undergo polycondensation reaction with polycarbonate, nylon, polyoxymethylene, thermoplastic polyurethane, PBT and the above polymer blends, but it is most effective for PET, and the worst for nylon, can be associated with it. The reactive groups include amide groups, isocyanate groups, carboxylate groups, and hydroxyl groups.

CESA-Extond improves the melt strength of recycled PET resin, which is sufficient for PET extrusion blow molding (bottle) and even the extrusion blown film process. Unreacted recycled PET with intrinsic viscosity of 0.75 is reacted with 3A A-Extend. After exiting, the intrinsic viscosity increased to 0.78, while in the same no vacuum and the same starting resin and extrusion process conditions, the intrinsic viscosity of recycled PET without chain extender decreased to 0.543. Intrinsic Viscosity 0.558 Recovered PET plus 2 蜸 A-Extend The intrinsic viscosity is increased to 0.673 after extruding by a twin-screw machine. If 3% of chain extender is added, it can be increased to 0.720.