The hottest new method to improve the grade of rec

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New methods to improve the grade of recycled PET resin

the global plastic environment conference of SPE (American Plastic Engineering Association) held in Detroit, USA (GL in the view of Ma Zhanfeng, Secretary General of China plastic processing industry association, obal plastics enviromentalco also nference) provided some new development achievements, including new additives to improve the grade of recycled PET bottle resin

the new additive introduced at the SPE meeting is the reactive series additive CESA extend of Clariant masterbatch company, which is used to branch the long chain of pet molecules and improve the characteristic viscosity of recycled PET without solid-state reaction in the reactor. After adding CESA extend chain extender, the molecular weight of pet increases to the equivalent molecular weight of the new pet resin without reducing the mechanical properties, thermal properties and crystallinity. In addition, CESA extend is easy to use. Generally, pet chain extension needs to be heated and pre dried under high vacuum for several hours. Sometimes, the branching reaction can not be controlled to produce gel. Now, adding CESA extend through twin-screw extruder does not need to be pre dried under high vacuum, but only produces a small amount of gel when the applied stress reaches the yield limit

Another function and advantage of Clariant's new chain extender is to improve the compatibility of recycled PET when mixed with other polyester, polycarbonate and nylon. This active additive is a special functional acrylic oligomer provided by Johson polymer LLC, Wisconsin, USA. the company and Clariant co own the technical patent of this product. It is reported that CESA extend can polycondensate with polycarbonate, nylon, POM, thermoplastic polyurethane, PBT and the above polymer blends, but it is the most effective for pet and the worst for nylon. The groups that can react with it include amide group, isocyanate group, carboxylate group and hydroxyl group

cesa extrude improves the melt strength of recycled PET resin, which is enough to meet the requirements of pet extrusion blow molding (bottle) and even extrusion film blowing process. After the reactive extrusion of non dried recycled PET with an intrinsic viscosity of 0.75 and 3% CESA extend, the intrinsic viscosity rises to 0.78, while under the same conditions of no vacuum pumping and the same initial resin and extrusion process, the intrinsic viscosity of recycled PET without chain extender decreases to 0.543. 2. For materials with large deformation, due to excessive deformation, the characteristic viscosity is 0.558. The characteristic viscosity of recycled PET plus 2% CESA extend is increased to 0.673 after extrusion by twin-screw machine. If 3% chain extender is added, it can rise to 0.720

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