Eco Friendly 3D Printing? The Promise of PHA

In our last article in our series covering 3D printing in a climate-disrupted world, we discussed the myriad problems associated with polylactic acid (PLA), the most popular plastic and bioplastic for desktop 3D printers. Here we’ll break down one of the more interesting alternatives to PLA that is emerging on the market.

Polyhydroxyalkanoates (PHAs) are a family of polyesters formed through bacterial fermentation of lipids or sugars. What sets it apart from PLA is the fact that it will decompose in soil and waterways, though it is more than twice the price of petro-plastics.

Polyhydroxybutyrate (PHB) was the first PHA polymer to be discovered and commercialized, beginning in the 1970s when the first petroleum crisis drove businesses and inventors to look for alternatives to petro-based plastics. With properties similar to polypropylene, the material offers such beneficial characteristics as biodegradability, biocompatibility, piezoelectricity.

Since the 1970s, new varieties of PHAs have been developed, as have new industrial-scale production techniques. PHBV, PHBHHx, and P3HB4HB are all newer forms of PHAs that overcome the fragility and rigidness of PHB. In particular, these materials have found important use applications in medicine due to the fact that they are not just biocompatible, but they safely dissolve in the body.

To manufacture these materials, bacteria is usually fed oil from plant seeds, including canola, soy, and palm within large tanks. The biomass is then extracted from microorganisms to isolate the PHA. The PHA is dried, resulting in a powder that can be pelletized and combined with additives in order to produce the desired physical properties. This includes heat-resistance and fire-resistance.

Companies involved in the production of PHAs include Yield10 Bioscience (formerly known as Metabolix, Inc.), CJ CheilJedang, Danimer Scientific, Zhejiang Tianan Company, Tepha (a spin-off of Metabolix), Tianjin Green Biosciences, and KANEKA.

The market for PHA is currently very small, at just $73.9 million in 2018 and expected to reach nearly $123.7 million by 2028, according to Prudour Research. In part, this is due to the fact that petrochemicals dominate the industry, making petro-plastics much cheaper to produce. In contrast, there is very little PHA production. The estimated 11.2 percent compound annual growth rate of the PHA market between 2019 and 2024 is driven by regulations around petrochemicals, single-use plastic and the need to diversify our plastic sources, given the instability of oil.

Historically, Metabolix, now Yield10 Bioscience, is the biggest manufacturer of PHA at 50,000 tons per year. For a comparison, NatureWorks, the largest producer of PLA, was making 150 kilotons of PLA per year in 2014. While PLA represents 13.9 percent of the global bioplastics market, at about 2 million tons annually, PHA accounts for a mere 1.2 percent

Companies, including a couple of promising startups, are continuing to invest in new strains of PHAs and new methods of production. Some of the most exciting means of manufacturing PHA feature converting plastic waste, water waste, and even greenhouse gasses such as methane and carbon dioxide into PHAs. Genecis is a Canadian startup that has developed a method for converting food waste into PHA and believes it can do so at a cost of 40 percent less than mainstream commercial methods.

There is some research into creating PHA plastics experiments in which the resulting material is 3D printed or bioprinted; however, you can get your hands on some PHA to print with right now. Colorfabb offers a wide variety of PHA/PLA blends, which feature PHA in order to create a tougher, less brittle PLA, though we are not sure exactly what the ratios of PHA to PLA are in these filaments.

In our next post, we will cover some other bioplastics in-development or already used in 3D printing, including chitin and cellulose.

[Feature image courtesy of the Journal of Biomaterials Science Polymer Edition.]