That compostable cup marked for the compost bin may still need an industrial sauna to disappear. University of Minnesota researchers say a trace chemical additive could help PLA plastics break down at lower temperatures, potentially nudging everyday packaging toward actual backyard composting—though the work is still in the lab-testing stage.
Researchers at the University of Minnesota Twin Cities developed the strategy for polylactide, or PLA, a plant-based plastic used in food packaging, cups and cutlery. As reported by the University of Minnesota, the problem is that most PLA products still need industrial composting conditions, while only about 18% of the U.S. population has access to those facilities. Much of the supposedly compostable material therefore ends up in landfills.
How The “Masked Acid” Works
The team added 2-sulfobenzoic acid cyclic anhydride, abbreviated SAn, to the PLA. According to the ACS Central Science study, the compound acts like a “masked acid”: It stays dormant during normal use, then reacts with moisture, temperature and time to produce acidic compounds that break the plastic’s molecular chains.
The additive appears to do its job in remarkably small doses. The researchers found that concentrations as low as 0.01% could accelerate PLA’s breakdown while preserving strength and durability, meaning the package would not be designed to self-destruct during lunch.
Promising Results, With A Big Asterisk
In one experiment, PLA containing 0.1% SAn reached 90% biodegradation in 11 days at 58 degrees Celsius. That is a striking result, but 58 degrees Celsius is closer to the controlled heat of industrial composting than the conditions found in many backyard bins…