MATERIALS | BIO-BASED PLASTICS


injection moulding, spinning and foaming equip- ment, which avoids the need for further investment. Within this new class of bio-based LPAEs are a variety of products with a range of hardness, including 30D and 65D. Injection moulding processability is similar to other thermoplastic elastomers, such as Pebax (another polyetheramide, which itself is available in partly bio-based versions) and Hytrel (a copolyes- ter). The elastomers need to be dried, and then


processed at temperatures of 200℃ to 240℃. Mould surface temperatures in the range of


20-40℃ are optimal. Cathay selected Arkema’s polyamide elastomer,


Pebax, as the reference material, and compared the properties of PA5X-65D. The Taber abrasion performance of PA5X-65D and Pebax 7233 are both excellent, up to 23-26mg according to the standard ASTM D4060-19. In addition, tensile stress and break elongation are similar. PA5X-65D’s break elongation is more than 500%, and Pebax 7233’s is less than 300%. Liu and his colleagues say the polyamide elastomer’s unique combination of strength, flexibility and excellent resilience make it a strong candidate for high-end sporting footwear. Other market opportunities for polyamide elastomers exist in automotive, transportation, and telecom- munication because of its mechanical properties, easy processibility, and the good surface appear- ance of finished parts. It can also be used for medical tubing. Numerous polyamides can now be made at


Mechanical properties of Cathay Biotech’s PA5X elastomers Source: Cathay Biotech


least partly using renewables. Most of them have been long-chain polymers, often for use in extru- sion applications. But last October, Lanxess launched Durethan Blue BKV60H2.0EF, based on PA 6. It says 92% of the raw materials used in this easy-flowing compound have been replaced with sustainable alternatives, “more than in any other prime quality glass-fibre-reinforced plastic”. This grade is the first product from Lanxess in the new “Scopeblue” series. The brand label identifies products that either consist of at least 50% circular (recycled or bio-based) raw materials, or whose carbon footprint is at least 50% lower than that of conventional products. PA 6 is polymerised from cyclohexane, and it is this chemical that Lanxess obtains by one of three routes: it is either bio-based, recycled bio-based or produced by means of chemical recycling. Com- pounds are strengthened with 60% by weight of glass fibres comprising industrial glass waste instead of mineral raw materials. The alternative raw materials that Lanxess uses


Graph shows theoretical and actual elastic recovery performance of three TPEs under identical strain conditions. In an ideal elastomer, when the load is removed, recovery should follow the same path as elongation. However, displacement of the polymer chains dissipates energy, resulting in a permanent deformation. Load to achieve a particular elongation depends on the hardness of the elastomer. The hardness of Cathay’s PA5X-65D’s is between that of Pebax 7233 and Pebax 6333, as is its elastic recovery. Source: Cathay Biotech


42 INJECTION WORLD | June 2022


in the precursors for PA 6 are chemically identical to their equivalents of fossil origin, so Durethan BlueBKV60H2.0EF exhibits the same characteristics as the virgin material and can be processed just as easily using exactly the same production tools and facilities with no conversion work needed, Lanxess says.


Guenter Margraf, Head of Global Product Management at Lanxess High Performance Materials (HPM), says the company is currently working on increasing the content of sustainable raw materials in this compound to 100%. This requires ammonia synthesised with carbon-neutral hydrogen, he says. Over the medium term, the


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