Previously, I wrote an article on polyaryletherketones (PAEKs), which stimulated quite a lot of response. I think it is useful to revisit the subject to share some of the thoughts of readers, research the subject a bit more and also add in a few new developments in the field.
A historical perspective
In my original article, Dave Thornley, an electrical engineer at TE Connectivity specialising in nanotechnology and polymer chemistry, commented on the history of polyarylenes, saying that the first large scale use of polyarylenes was in fact for aircraft wire. The polymer was made by Raychem Corp in Menlo Park California, under the trade name Stilan. Introduced in 1972, the wire was covered by various slash sheets in military specification wire, Mil W 81044.
The major customers were Boeing and Douglas who used it extensively on 747 and DC10 aircraft; it was also specified on numerous European and US military and commercial programs. It was qualified in the UK to DGS 344 which was the Navy low fire hazard equipment and multicore component wire standard.
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According to Thornley, Imperial Chemical Industries (ICI) introduced their polyetheretherketone (PEEK) polymer as a result of pressure from all the UK wire manufacturers, who saw their speciality wire market disappearing. Subsequently, Raychem withdrew the product in 1977 following the collapse of the commercial aircraft market after the second oil crisis. They sold off the process for making it to BASF but BASF did not pursue it.
Of interest are the limitations of polyarylenes, which Thornley remarks are not widely publicised.
- The UV resistance is different for the different polymers
- They are generally susceptible to solvent stress crazing to a small range of solvents.
- The modulus temperature curve goes through some deep dips where the polymer undergoes a structure change.
- But the flex life is outstanding and the very low temperature performance is outstanding.
Jonathan Jurgaitis of Apollo Medical Extrusion Technologies in Utah commented to say that he frequently extrudes these materials and is very pleased with his results. He has also seen a growing acceptance of extruded components comprised of PAEK variants as replacements for stainless steel tubing and for micro-bore tubing applications in the medical sector.
Solvay Specialty Polymers
While Solvay Specialty Polymers no longer supports the Proniva material, one new development from Solvay is noteworthy. Performance Plastics is using Solvay’s Torlon (polyamide-imide) PAI to make a new line of EnduroSharp Scraper Blades for aerospace maintenance applications. Torlon PAI enabled these unique new tools to be tough enough to maintain their edge longer than blades molded from competitive polymers, but safe enough to remove challenging materials from delicate surfaces.
The recently launched Torlon PAI blade handles and inserts enable aerospace maintenance professionals to safely remove elastomeric coatings, boots, tapes, sealants, adhesives, gap fillers and tape residue from fiber-reinforced composite, plastic, glass, ceramic or metal substrates and fasteners. The PAI blades can also be used in conjunction with heat- or chemical-assisted skiving processes to expedite material removal.
While polyetherimide (PEI) and polyetheretherketone (PEEK) were candidates for this application, both materials needed to be machined from molded blanks to give the blade a sharp edge. In comparison, Torlon PAI’s excellent processability allows the blades to deliver a sharp edge right out of the mold – eliminating the time, cost and material waste of machining.
Solvay’s material, however, can be machined to permit one-off designs, such as blades that incorporate a gap to scrape around fasteners. Torlon PAI’s thermoset-like properties also allows EnduroSharp blades to withstand the high heat and friction of resharpening, which can result in a burr on blades fabricated from PEEK and PEI polymers.
Albert Jan Westerhof of De Monchy International, a consultancy specialising in products for coatings, adhesives, thermoplastics, waxes and food ingredients, raises a flag for a new-to-me supplier, Gharda Plastics. This global science-based company is active in polymers, pigments & agrochemical materials. It is headquartered in Mumbai, India, with manufacturing facilities located in Mumbai & Lote (Maharashtra), Panoli & Ankleshwar (Gujrat).
Gharda has recently commercialised the high-performance engineering thermoplastic, Polyetherketone (PEK) under the trade name G-PAEK, using, it says, in-house patented technology. The company also produces Polybenzimidazole (PBI) and Polyetherketoneketone (PEKK). PEK is a semi-crystalline polymer, with a high glass transition temperature of 152°C and melting temperature of 372°C.
Additionally, the company offers various filled grades with improved strength for demanding opportunities that require high wear resistance. The heat deflection temperature of these grades can be as high as 360°C, providing strength and stability in extreme conditions.
According to company sources, G-PAEK has the following advantages:
- Delivers up to twice the wear resistance of PEEK at high temperatures
- Retention of mechanical and physical properties up to 30°C higher than PEEK, supporting higher loads without permanent deformation
- Improved compressive strength
- A strong candidate for engine parts, subsea connectors and heat exchanger applications
- Excellent gamma radiation resistance
- Excellent hydrolysis resistance at high temperatures
- Excellent high temperature performance for all mechanical properties
- Excellent electrical performance at high temperatures
- Excellent chemical resistance at high temperatures
GA-PEKK combines high temperature stability, strength, stiffness and ease of processing. PEKK has superior temperature resistance than other Ketone base polymers (PEK & PEEK). It has excellent compressive strength, creep resistance, wear and radiation resistance and also inherent flame retardancy.
With a glass transition temperature of 176°C and a melting temperature of 395°C, GA-PEKK polymer delivers extended high temperature mechanical performance over standard PEKK polymer and chemical resistance. Available as unfilled, glass filled and carbon filled grades.
- High (300°C) continuous service temperature (estimated)
- Highest compressive strength in Ketone family polymers, making it suitable for oil and gas industries
- Excellent electrical resistance
GA-ZOLE is a semi crystalline polymer containing benzimidazole group (PBI, poly (2, 5-benzimidazole), with high thermal and chemical stability. The dope solution in methane sulfonic acid is recommended for Fibre Spinning and Membrane, while powder is useful for the Sintering compression moulding process at high temperature & pressure to make parts. It has very high limiting oxygen index (LOI), heat deflection temperature (HDT) and is recognised for its non-flammable characteristics.
With a glass transition temperature of 485°C, GA-ZOLE polymer delivers extended high temperature mechanical performance over standard PBI polymer and excellent chemical resistance. Available as unfilled, glass filled and carbon filled grades.
- Sintering compression moulding process at high temperature & pressure to make parts.
- Offers the highest heat resistance and mechanical property retention over 310°C.
- Lowest coefficient of friction and highest wear resistance properties.
- Low out gassing in vacuum (dry material).
High-performance FDM filaments
At RAPID + TCT 2017, SABIC unveiled a new portfolio of high-performance filament grades for fused deposition modelling (FDM). The new products address growing global demand for greater material choices in the industrial filament market and help lay the groundwork to drive the growth of additive manufacturing from a prototyping technology to full-scale production.
SABIC’s new filaments, designed for use with Stratasys Fortus printers, are based on the company’s ULTEM polyetherimide (PEI) resin, CYCOLAC acrylonitrile-butadiene-styrene (ABS) resin and LEXAN polycarbonate (PC) resin, and offer the same compositions as the company’s injection molding grades. Manufacturers can use the filaments to produce a range of high-performance, durable end-use parts.
Both ABS and PC are well-established materials for additive manufacturing of prototypes and end use parts, while ULTEM (PEI) filament is desirable for demanding applications that require high heat resistance, high strength, and low flame, smoke and toxicity (FST).
ULTEM AM9085F filament is a high-performance PEI product manufactured from ULTEM 9085 resin. This product provides high heat resistance and mechanical strength, is UL94 V-0 compliant at 1.5 and 3.0mm, and meets FAR 25.853 and OSU 65/65 requirements with low FST evolution. It is available in black and natural (unpigmented) colors. The EXTEM thermoplastic polyimide filament has heat resistance exceeding that of ULTEM filament.
The views, opinions and technical analyses presented here are those of the author, and are not necessarily those of UL, ULProspector.com or Knowledge.ULProspector.com. While the editors of this site make every effort to verify the accuracy of its content, we assume no responsibility for errors made by the author, editorial staff or any other contributor. All content is subject to copyright and may not be reproduced without prior authorization from Prospector.