Nearly all articles found at PlasticsToday center on a fresh news of some sort, whether it’s business, technology or something else.
This time, a story lead was generated by an atypical source: our readership, who collectively continued showing high interest on a monthly basis for one particular feature from April 2018, PHA bioplastics a ‘tunable’ solution for convenience food packaging.
The reason? Continued curiosity in bioplastics in general and a particular fascination with the unique properties of polyhydroxyalkanoates, aka PHA (broad range of uses is shown in the chart above).
“PHA’s most exciting feature is that it possesses a ‘tunable’ property set,” explained Catherine Joce of Cambridge Consultants (Cambridge, England) in that feature. “PHA is not one chemical structure, it is actually a whole family of related polymers. Depending on the production process and the feedstocks used, different polymers with different physical properties can be produced.”
If there’s that much current interest in an older article, why not check in with the consultancy and find out what’s new? So we did, and it turns out there’s a lot going on. This update is courtesy of the expertise of Steve Thomas, the firm’s senior consultant, who answers our many questions about this specialty bioplastic.
What feedback did the company receive from that first article that proved so popular with our readers?
Thomas: The article gave rise to a lot of interest. The whole plastic pollution issue has had lots of people looking for more sustainable alternatives to traditional plastics. Many companies don't have the option to move away from plastic altogether, so they've been investigating bioplastics as an alternative.
How would you characterize the interest in these materials now?
Thomas: The U.S. has been surprisingly switched on about the whole area. We've had some large companies looking to make their plastic consumables more sustainable. We've also had some financial institutions who are interested in pushing their portfolio companies in a more sustainable direction. PHAs and other bioplastics are an interesting potential solution to some of these problems but we're encouraging everyone to look at their whole product lifecycle and the user journeys involved with their consumables. Design for end of life is a very important aspect of sustainability.
What’s been the firm’s activity in PHA these past 12 months since that article appeared?
Thomas: Over the last 12 months we've worked with several companies to analyse their product strategies. We've also been contacting many bioplastic vendors in order to build a database of different materials that are available. More recently, our Synthetic Biology Group has begun work on engineering bacterial strains to grow PHAs in our own labs. We're very excited about this piece of work because it brings the whole story full circle.
What has the company learned about PHA and other biodegradable polymers since then?
Thomas: We've learned that biodegradable plastics are only a small part of any solution. To be effective, you must design your product to make proper disposal an easy option for the user to take. It's really important to think of the whole product lifecycle. For example—PLA (polylactic acid) is a more common biodegradable plastic than PHA. It's clear and looks a lot like PET so people make drinking cups and bottles out of it.
Unfortunately, you need the really harsh conditions of industrial composting to get it to biodegrade. So, you don't really benefit in making product out of PLA if you're going to release it in a city that doesn't have an industrial compost collection that's willing to take it. Most places would see it in compostable waste and think it was PET. You can't put it into your recycling because it will contaminate the other plastics. The only option is to send it to landfill—where it won't actually degrade.
By contrast, PHA will degrade in regular compost and will also degrade if it's discarded in the environment. We've worked through some life cycles for some disposable products where we've modified the product design to make it more likely for the user to take it home and put it in their compostable waste. We've selected PHAs for some of those designs to cover the inevitable cases of improper disposal–when a user disposes of the product by discarding it in the environment. PHA will degrade in soil and in the ocean as well. but it isn't instant—it will still persist for several weeks or longer if the plastic is thick.
One of the other things that we've learned about biodegradable plastics is that the industry is still very embryonic. A large proportion of the companies marketing PHA and other biodegradable plastics do not yet have full production capacity. Very few of them will agree to sell you materials and instead want to enter into six-digit development programs. This makes it tough for companies (especially smaller ventures) to look at producing products in bioplastics. And there are only a very small number of practical suppliers to work with.
Next: Applications, latest research and more
What application has proven a winner for PHA this far? And where else does PHA hold much promise?
Thomas: The biggest use of PHA at the moment is probably mulching film—a plastic barrier layer that’s laid down in arable land to prevent weeds from penetrating and disturbing crops. Traditionally these products were made of polyethylene—and would often be plowed back into the land at the end of the season—and eventually ruining the soil with plastic fragments. Making this film out of PHA means that you can deliberately plow it back into the field, knowing that it will have degraded away harmlessly by the following season.
The high temperature performance of PHA still provides promise for plastic consumables used with hot beverages. Newer versions of other plastics like C-PLA can now withstand the kinds of temperatures that hot drinks inflict on them, but PHA remains the only soil- and marine-biodegradable polymer that can take temperatures above 80 deg C/176 deg F.
PHAs are especially useful for other applications in agriculture where it is useful to have plastic items that are designed to be left in the environment. Ties and labels for plant, temporary root pots that degrade into the soil, many of the other small plastic parts that you would see around commercial green houses and plantations.
What’s changed in the market these past months?
Thomas: Many companies are appearing and presenting more new options for biodegradable polymers. Many of these are bio-derived, like PHA. Others involve synthetic modifications of biopolymers with more conventional materials. Significantly, as well as the start-ups, more of the big polymer manufacturers are adding bioplastics to their portfolios. This is a key development because these players have the capacity, scale and production experience to deliver bioplastics at useful commercial quantities and with commercial quality too.
What kind of research is the company involved in either directly or indirectly in this market?
Thomas: Our newest area of research associated with bioplastics is that we are now developing our own strains of bacteria to produce PHAs. We are setting up fermenters to produce PHA from our own strains of bacteria. One of the other attractive aspects of PHA is the ability to engineer bacteria to produce it from a variety of feed stocks. The easiest way to produce PHA is to feed the bacteria on sugar, starch or vegetable oils—all primary food crops. However, with the right engineering it will be possible to allow the bacteria to digest waste products or by-products from our existing food production processes. Using materials like spent coffee grounds, wort left over from brewing processes and the tough and woody stalks and shoots left over from fruit and vegetable crops, really exploits the potential for true sustainability and efficient use of resources.
What else would you like to mention?
Thomas: Although PHAs and other bioplastics are a very interesting and important area of work for us, we are keen to help our clients find the most sustainable way ahead for their products. In many cases this may be to stick with conventional plastics, but to design products to be more recyclable. There is still a lot of work to do in how conventional plastics are recycled. A lot of the material which we send for recycling is actually down-cycled—reprocessed into a lower value item. Milk cartons getting turned into traffic cones or garden furniture, PET bottles being shredded to make insulation material for buildings or filling for soft furnishings. The carbon footprint of bio-derived plastics is relatively low in comparison to fossil-derived materials, but they are still not suitable for all applications. Developing efficient and truly circular economies for conventional plastics like PE and PET is still a vital activity to reduce the impact of what are actually tremendously useful materials.
Image courtesy Slavko Sereda/Adobe Stock
