Teijin developed three different ThermoPlastic Recycling Solutions: Compound, Chips and Crushed. They are reinforced material combinations made of recycled Tenax™ carbon fiber and recycled semi crystalline polyetheretherketone (PEEK) polymer to offer high performance in strength and stiffness for injection molding applications.
Teijin have been active for many years in the CFRTP market and intelligently developed the product range of Tenax™ ThermoPlastics (TPUD and TPCL). These materials offer a rapid production and processing, low scrap rates, high mechanical performance, strong chemical resistance and recyclability. The TPCL are qualified for the application in “clips and brackets” in the A350XWB aircraft, Airbus’s new-generation extra-wide-body midsize jetliner.
In consideration of the aircraft production ramp-up and the increasing material consumption of these high valuable materials, efforts have been made to develop recycling solutions with an immediate effect. Teijin’s intention was to develop a closed-loop-concept for the thermoplastic materials and to reconvert the exceptional properties of this high performance material combination.
Teijin is developing different “green“ CFRTP routes for individual products to serve a wider field of potential production processes and applications. In this context, the group intends to offer Tenax™-E TWPF PEEK-HTA40 CHIPS which are made of carbon fiber and virgin PEEK (Poly-Ether-Ether-Ketone) polymer. TPWF material is reclaimed during the production process of the A350 XWB qualified Tenax™ TPCL and reprocessed by a cutting process into Tenax™ Chips. The concept is to offer the material in a variety of sizes, such as +/- 5 mm x 5 mm or even up to +/- 50 mm x 50 mm. Finally, the Chips sizes are specified by the market requirements accompanied by the processability and requirements of the final components.
Background: A 3-D stamp forming process with thermoplastic materials allows the production of complex 3-D “clips“. In the first production step, individual preforms are nested and cut out of the original laminate dimensions of 800 mm x 1.200 mm, heated to processing temperature of the polymer matrix and quickly stamp formed in a metal mold in the second production step. In spite of the endeavor to arrange the precise nesting and therefore an optimum buy-to-fly ratio in particular, a thin TPCL grid will remain for certain.
In parallel to the Tenax™ Chips, the material concept also includes the implementation of a recycling flow for Tenax™ TPCL production by-products occurring during the 3-D stamp forming process at the part makers. Teijin plans to transform these by-products into Tenax™-E TPCL PEEK-HTA40 CRUSHED. This crushed CFRTP will be available in random sizes due to the applied crushing/shredding process, but downstream sieving stages could generate a more homogenous raw material for further processing steps. Obviously once again the grade of the material can be optimized depending on component requirements.
Tenax™-E COMPOUND rPEEK CF30 is a reinforced material combination of recycled 30% carbon fiber by weight and recycled semi crystalline PEEK polymer which offers a high performance in strength and stiffness for injection molding applications. This compound has an almost identical performance to virgin standard material in terms of tensile modulus and strength, which also includes elongation, viscosity, chemical resistance, abrasion and a very low moisture to absorption ratio, to round off the highlight characteristics of this recycled material. The created value of this compound is linked to the combination of high performance materials as well as a low-cost price of 40-60 % compared to virgin carbon fiber reinforced PEEK compounds.
In conjunction with our partners, an OEM Aircraft manufacturer and Sintex NP Group, we have demonstrated that a serial Aircraft “Wing Access Panel“ can be manufactured to prove the performance of the recycled granules. The Sintex NP Group was selected as the partner responsible for the part manufacturing process based on Tenax™-E COMPOUND rPEEK CF30 and the assessment of material processability compared to today’s virgin material standards within their production processes. It was shown that it is possible to combine best performance with full manufacturing and design flexibility without any parameter adjustments in the production chain. This way Tenax™-E COMPOUND rPEEK CF30 is able to reduce the part costs significantly.