Standards for Biodegradable Plastics

From toothbrush handles and computer keys to aviation components and medical devices, plastics have become an ubiquitous part of modern life. To keep up with demand, manufacturers produce between 270 and 360 million Mg (300 and 400 million tons) of plastic worldwide each year. Unfortunately, what happens once plastics outlive their usefulness has become a troubling issue of our age.

The amount of plastic waste discarded has galvanized some people against these polymers. According to a report from the Royal Statistical Society, as of 2017, only nine percent of plastic was recycled while 12 percent was incinerated. The remaining 79 percent went into landfills and the environment. According to a study published in Science magazine, roughly eight million metric tons of plastic end up in the world’s oceans each year. A key group working to alleviate these problems and support safe plastics disposal is ASTM International’s subcommittee on environmentally degradable plastics and biobased products (D20.96), part of the plastics committee (D20).

The D20.96 subcommittee organized in 1990 at a time when manufacturers boasted of making eco-friendly products without any verification of their claims. These were the early days of environmentally degradable plastics, with no standard practices, test methods, or specifications. Subcommittee D20.96 then began the hard work of developing these much-needed standards to establish degradability and biodegradability and assess the impact of degraded plastics.

Originally, the group focused on environmental concerns such as composting biodegradable polymers and paper alongside food, yard, and agricultural waste, and the need for compostable diapers. Marine life consumption of polyethylene carry-out bags and wrappings, as well as both sea and land animals becoming entangled in beverage rings, became major issues in the public eye, says Ronald Walling, president of the Advanced Materials Center Inc. and former D20.96 vice chair. 

To control the environmental impact of plastic bags and beverage rings, the subcommittee developed the practice for fluorescent ultraviolet exposure of photodegradable plastics (D5208). “ASTM D5208 was developed with Union Carbide, Triangle Labs of North Carolina, ITW - Hi Cone of Illinois, and Advanced Materials Center Labs cooperating in a joint venture to develop a controlled, accelerated test to simulate actual outdoor conditions,” Walling comments. “Tensile evaluation was developed and round-robin tested to ensure proper documentation of this type of degradation.” 

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