Designing Medical Polymer Solutions for Environmental Sustainability

A combination of this extensive polymer expertise and increasing customer demand for sustainable solutions were the impetus for a new product development initiative. The result is Hostaform MT POM ECO-B, a sustainable alternative to standard Hostaform MT POM for companies seeking to reduce their carbon footprint. Hostaform MT POM ECO-B contains up to 97% bio-content using an ISCC+ certified mass-balance approach. Hostaform MT POM ECO-B’s CO2 footprint per kilogram of polymer is less than half that of regular Hostaform MT POM (Figure 1), and yet is considered an equivalent virgin material, a feat achieved by the conversion of bio-gas into plastic.

Rob Haley, Global Marketing Director, Medical & Drug Delivery Devices, at Celanese, highlights that “Because Hostaform MT POM ECO-B is functionally the same material as Hostaform MT POM, Celanese can offer its partners exactly the same regulatory service support they have come to expect. Celanese’s full MT Portfolio service package, including drug master files, letters of authorisation for regulatory filing support, and biocompatibility compliance, is available for Hostaform MT POM ECO-B.”

THE MASS-BALANCE APPROACH

A variety of reaction steps go into making POM, but the starting molecule is methanol, which can be produced from several energy sources, including methane (commonly known as natural gas). Methane can be found in the ground as fossil fuel, but, alternately, can be captured when released by organic matter decaying in an anaerobic environment. Kevin Norfleet, Senior Program Manager at Celanese, explains that “The mass-balance approach preserves Celanese’s production scale and efficiency. The sustainable feedstocks are fed into the start of the process and then accounted for separately to allocate the benefits to specific products at the very end.”

This is a similar principle to “green” electricity. When it’s on the grid, all electricity is equal, so purchasing green electricity is a question of accounting; marking off electricity used by the buyer against electricity that was sustainably produced. It’s the same for a chemical process like the production of POM. Once in the polymer production process, both fossil-based and bio-based feedstock can be mixed, but accounted for separately, with conventional Hostaform MT POM produced by mass of conventional feedstock used, and Hostaform MT POM ECO-B produced by mass of green feedstock used (Figure 2).

POM ECO-B involves no change in the downstream manufacturing processes and no need for product requalification.

The methanol used to produce Hostaform MT POM ECO-B uses bio-gas as feedstock, a mixture of gases produced by the anaerobic respiration of bacteria during the decomposition of organic matter, such as agricultural waste and sewage (Figure 3). Bio-gas is a renewable resource, but also a potent greenhouse gas if not collected; by using it as feedstock it creates both a more sustainable material and a robust market for the collection of bio-gas.