Bioresins: Not a tsunami, but more like a rising tide

I’ve been thinking about sustainability recently, and renewable, “green” resins, because I was tasked with writing a feature article for an upcoming issue of CW magazine. Initially, I was stumped, because I hadn’t heard a lot of news or activity around bio-sourced polymers. But, at the recent Society of Plastics Engineers (SPE) Automotive Composites Convention and Exhibition (ACCE) event in Detroit (link to the show report here: http://www.compositesworld.com/articles/spes-acce-2015-preview ), wow — the automotive sector appears to be really taking the lead in this area, and had much information to share. That led to more information from some innovative green resin companies and research groups, including National Research Council Canada, Entropy Resins, Dixie Chemical, Eastman Chemical, and Solvay, in addition to well-known composite resin companies who offer bio-sourced resins (Ashland, AOC, DSM, and Reichhold).  

It’s not as if the composites industry is going to change to bio-sourced, green technology overnight. My take is that a lot of investigation is happening, and some promising applications are developing, that will slowly gain market share, particularly in areas, like automobiles that are marketed to consumers who value a renewable/biodegradable/biobased value-add. Here’s a preview of the article, which will appear in full in our December issue.

CW first wrote about bio-based resins in 2008, when the price of a barrel of oil topped $110, which made plant-based polymers look pretty good. We tackled the subject again in late 2011, when it appeared that sustainable resins would break through, noting significant investments by several market players in bio-resin processing facilities. It was a hot topic at that point, says Robert Moffit of Ashland Performance Materials (Dublin, OH, US), and was attracting a lot of attention and money.

What’s happened since? Fracking, the technology that enabled extraction of oil and natural gas from tight formations, changed the picture, especially in the US, helping to drive the price of oil down significantly (its present level is about $42 USD per barrel). “The drop in oil prices made petroleum-based monomers such as olefins much cheaper, and the green-based materials had trouble competing,” states Moffit. “Cost has been the big influence, depressing the sales of the green products.”

That said, an ever-increasing push for sustainability and a reduced carbon footprint, especially from younger consumers coming to the marketplace, has helped maintain an interest in renewably sourced resins. While they might not be widely used, yet, nevertheless green polymers are being created and used in some surprising ways. One automotive source says “Bioresins have been around for decades, and a low oil price won’t stop their development. Bio-materials offer light-weighting opportunities better than any other products, and they’re not going away.” This article’s focus is on bio-based resins; watch for our story in 2016 on the growth of renewable biofibers and biofillers for composites.

A bit of bio background

Bioresins can be derived from a huge range of biological carbon sources. As we reported in our 2011 article, the biomass is broken down using adapted chemical processes in a bio-refinery, to produce monomers that in turn can be polymerized to obtain bio-based polymers. Dr. Karen Stoeffler, leader of the Polymer Bioproducts team at National Research Council Canada (NRCC, Boucherville, Quebec, Canada) explains, “For example, fermentation of sugarcane molasses leads to bio-ethanol, which has exactly the same chemical formula and the same properties as ethanol derived from petroleum. With a conventional dehydration reaction, it’s converted to ethylene, which in turn is polymerized into 100% bio-based polyethylene, with exactly the same properties as petroleum-based polyethylene.”

Plant-based materials are more costly to process than a straight petrochemical, at least for now, because it typically takes a lot of plant matter to produce a biochemical compared to hydrocarbons. According to the web-based Polymer Innovation Blog by Jeff Gotro (Mar. 11, 2013), bio-refiner Braskem (São Paulo, Brazil) requires approximately 28 tonnes of sugar cane to make 2 tonnes of ethanol, which is converted to 1 tonne of bio-PE. In contrast, it’s been reported that 1 tonne of conventional PE can be produced from 1.6 tonnes of crude oil. Further, there is currently an unfavorable economy of scale compared to a traditional hydrocarbon sources, says Stoeffler: “The oil industry has been optimizing its processes for a century, but modern bio-refineries have only started working on the production of building blocks for polymers in the past 15 years. The processes are not yet necessarily optimized to ensure competitive costs.”

The added cost has inhibited the use of bioresins in a lot of composite applications, explains Moffit: “Typically, a bio-based resin historically has cost about 10 percent more than a petroleum-based resin, and as oil and petro-based raw material cost declines, this differential increases. Eight years ago, some bioresins cost the same compared to petroleum-based equivalents. For green resins to really take off, we need better cost parity compared to petrochemical products.” Despite these factors, bioresins are proven to perform. Researchers have routinely documented composite properties of bio-based composites as equivalent to traditional (petrochemical-based) composites.

Bio-based resins have definitely found a place in consumer applications where buyers are willing to pay a premium for sustainability. Case in point is Coca-Cola’s PlantBottle, introduced in 2009, which contains 30% bio-based polyethylene terephthalate (PET) derived from ethylene glycol from sugar cane molasses. Automotive OEMs are also actively researching use of biocomposites, particularly in interiors. Another big driver, says Moffit, is the Leadership in Engineering and Environmental Design (LEED) program of the U.S. Green Building Council: “LEED is driving builders, architects, designers and others to search out lower-impact products and building methods, and more ‘transparent’ materials that use fewer synthetic chemicals, which is creating opportunities for alternative resins.”