Turning Tree Blood Into Plastic

Resin leaks from a pine tree trunk. Photo by Robert Verzo / CC BY 2.0

Just as a bold piece of commentary recently published in Nature states in its title that we ought to “Classify Plastic Waste As Hazardous”, one researcher has come up with a unique proposal for making our societal addiction to plastic less harmful. Let’s use tree resin, suggests Chuanbing Tang from the University of South Carolina. That’s right: the impossibly sticky amber ooze that evergreens like conifer, pine, and fir trees leak when something breaks their bark.

Plastics, with their almost impossible resilience, have long populated landfills, refusing to degrade. Plastic bags particularly have become symbolic of plastic pollution, embodied by images of multicolored bags snagged on trees, or shrouding birds. With this problem in mind, Tang, who is a chemist, started exploring the possibilities bound up in tree resin.

Generally, plastic is derived from petroleum, since the technologies used to convert and process hydrocarbon—the base material used to make plastic—are much more developed in the petroleum industry. But that’s not to say that renewable sources of hydrocarbon are unrealized. Rosins and turpentines, which are ingredients in tree resin, are full of hydrocarbons that have similar properties to those that come from oil. The methods used to exploit this source are simply less developed.

That’s what Tang is hoping to change. As explained in the University of South Carolina press release:

Hydrocarbon-rich starting materials, whether from petroleum or tree resin, can be converted into various forms of what are commonly termed ‘plastics’ through polymerization.

The motivation for Tang’s move toward tree resins is that hydrocarbons from renewable sources are more likely to break down at the end of their life cycle, because they more closely represent their original natural structures.

“Most plastics from non-renewable resources are generally not biodegradable,” Tang said in the university press release. “With a polymer framework derived from renewable sources, we’re able to make materials that should break down more readily in the environment.” The ingredients that come from wood products like evergreen trees also make particularly reliable materials after they are polymerized, Tang said. 

Going forward, Tang’s aim is to improve understanding of the structure and properties of hydrocarbon molecules drawn from resins. Ultimately, he suggests that “If we can establish clear structure-property relationships, we will be able to achieve the kinds of results we now get from polymers made from petroleum” - with the added benefit of those polymers being biodegradable.

Compostable plastic? It certainly beats the sight of a landscape peppered with artificial plastic flowers.