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Specialty polymers demonstrate the advantages of single-use consumables in biopharmaceutical manufacturing.
Many companies are using single-use technologies (SUTs) to replace traditional reusable stainless-steel equipment in biopharmaceutical manufacturing. This transition is largely due to the reduction of time and costs associated with teardown-reset-cleaning-validation cycles, the elimination of the risk of cross-contamination, and the flexibility to produce small batches or niche products. Another driver of SUT adoption is the ability to establish regional manufacturing capabilities close to customers without a major capital investment in infrastructure and logistics.
Plastics are used to manufacture the majority of SUT components, such as bags, tubing, filtration media, and filter housings; connectors, valves, and clamps; sensor housings and gauges; and final fill and storage containers. While plastics can deliver performance properties similar to those of metal, such as stiffness, strength, and impact resistance, they also surpass metal in several important ways.
Polymers offer greater design freedom and lower system costs through high-volume injection molding, or extrusion, as well as optical and radio transparency, flexibility, corrosion resistance, weight reduction, and designs with improved ergonomics. But not all polymers can meet the stringent—and evolving—requirements of biopharmaceutical SUTs. Those demands call for plastics with a higher level of performance.
Specialty thermoplastics can replace not only metal, but also lower-performing polymers, to add value to SUTs and help address emerging industry challenges. By improving compatibility with chemicals and sterilization methods, reducing the risk of extractables and leachables (E&L) to increase the reliability and lifespan of SUT components, and expanding design and performance possibilities, these polymers can contribute to a manufacturer’s overall strategic objectives.
The baseline requirements for any plastic used in SUTs for biopharmaceutical processing include regulatory testing, biological safety, low E&L, chemical resistance, and the ability to be sterilized prior to use. However, for the best results, a polymer needs to deliver more than the minimum prerequisites. The following specialty polymers offer high performance properties and other attributes to meet the current and future needs of biopharmaceutical SUTs:
Polysulfone (PSU)—this rigid, high-strength, semi-tough, transparent plastic offers higher heat resistance and better hydrolytic stability than polycarbonate (PC). It retains its good mechanical properties when exposed to steam autoclaving and other sterilization techniques. PSUs are used in a variety of membrane filtration applications and fluid handling components in bioprocessing systems.
Polyethersulfone (PESU)—this transparent, flame-retardant polymer offers good toughness, strength, and hydrolytic stability. It withstands prolonged exposure to water, chemicals, and temperatures, retaining its transparency, mechanical properties, and dimensional stability in high-heat environments. Applications include monitoring and filtration devices and biopharma processing components, such as sight windows and quick-connects.
Polyphenylsulfone (PPSU)—this high-performance thermoplastic excels in high-heat/high-humidity environments. It offers impact strength similar to that of PC and better chemical resistance than PC or polyetherimide (PEI). PPSU also features inherent flame retardancy and long-term hydrolytic stability at elevated temperatures. It is compatible with all sterilization processes. Typical applications would be for higher performance sensor housings and fluid handling connectors and components.
Polyetheretherketone (PEEK)—exceptional performance in multiple areas, including chemical, fatigue, hydrolysis, heat, wear, and abrasion resistance, makes PEEK an excellent candidate for components used in the most aggressive chemical environments.
Polyarylamide (PARA)—typically reinforced with high glass fiber loadings, PARA still delivers high flow that enables thin-wall molding. High strength and stiffness, combined with a smooth surface finish, make this material suitable for metal replacement in SUTs, such as powder transfer valves and tri-clamps.
Specialty polymers can often address evolving industry requirements for SUTs in biopharmaceutical processing more effectively than metal or lower-performing polymers. For instance, many commodity polymers are formulated with processing aids and other additives that can raise product safety issues related to E&L. In contrast, high-performing specialty thermoplastics can accommodate a wider range of use environments without relying on stabilizers and other additives. The result is a cleaner, purer end product, with improved E&L.
Cost control can be another differentiator for specialty thermoplastics. If metal parts require machining, welding, polishing, and other secondary operations, total system costs can rise compared to injection molding or extruding a plastic part. In some cases, cost advantages can be achieved through part consolidation, which is often easier with plastics thanks to their design flexibility. Reducing the total number of parts can save material and increase throughput by eliminating assembly steps. Designs of high aspect ratio parts, such as fill tubes, are easy to do with a high flow, injection molded resin, but costly to machine.
Although they are single-use components, SUTs often need to perform effectively through the production of multiple batches of the same biopharmaceutical without having to be replaced. The superior properties of high-performance thermoplastics can help extend the useful life of the SUT component. For instance, improved chemical resistance helps avoid premature stress cracking that can occur with lower-performing polymers as well as galvanic corrosion that can affect metal parts. Greater resistance to high temperatures and other environmental factors can also minimize degradation, such as yellowing or haze in transparent thermoplastics, to ensure consistent performance of SUTs, such as optical sensors.
From the standpoint of sustainability, specialty polymers can expand the range of SUT components that can be developed and implemented, helping to further reduce the need for clean-in-place/sterilize-in-place components that require significant amounts of water, energy, and materials. They can also enable designs that reduce raw material usage; high-stiffness, high-flow polymers allow for the use of thin-wall designs and functional integrations that conserve resources and contribute to light-weighting efforts.
To help the industry feel more knowledgeable and confident about the performance, purity, and regulatory compliance of specialty thermoplastics in SUTs, suppliers are generating additional data and test results for their materials. Data on such factors as X-ray compatibility and cryogenic performance for cell-gene therapies at very low temperatures (-150 °C to -180 °C) can help quantify the advantages of adopting PSU, PESU, PEEK, PPSU, or PARA for biopharmaceutical processing components.
Anna Maria Bertasa and James Hicks are global marketing manager and application development and processing engineer, NA life solutions technical team, respectively, in the Healthcare dvision at Solvay Specialty Polymers.
Vol. 35, No. 7
When referring to this article, please cite it as A. Bertasa and J. Hicks, “Specialty Polymers Add Value to Single-use Technologies for Biopharmaceutical Processing,” BioPharm International 35 (7) 29–30 (2022).