Materials

Better, safer flame retardants may be made from plants

One of the esters used by the scientists was obtained from the buckwheat plant
One of the esters used by the scientists was obtained from the buckwheat plant
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One of the esters used by the scientists was obtained from the buckwheat plant
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One of the esters used by the scientists was obtained from the buckwheat plant

You've no doubt heard how the flame-retardant chemicals used in products such as furniture can make their way into the rest of the home, potentially causing health problems. Well, scientists are working on a solution, by replacing those substances with ones derived from plants.

Currently, the most effective flame retardants incorporate what are known as organohalogen compounds. Derived from petroleum, these can migrate out of the items to which they've been added, becoming part of the household dust and thus subsequently getting inhaled or ingested. Additionally, they may persist in the environment for years after those items have been discarded.

Because recent studies have suggested that organohalogen compounds may be neurotoxic, last year the state of California banned their use in children’s products, mattresses and upholstered furniture. Given that a less-threatening alternative is now needed, researchers at Central Michigan University are looking at two plant-based chemicals – gallic acid, which is commonly found in fruits, nuts and leaves; along with 3,5-dihydroxybenzoic acid, from buckwheat.

Led by Dr. Bob Howell, the scientists utilized a simple chemical reaction to convert hydroxyl groups from these compounds into flame-retardant phosphorous esters. Those esters were then added to a polymer epoxy resin, of a type commonly used in electronics, automobiles and aircraft.

When samples of the polymer were fire-tested, it was found that the esters reduced the intensity of the flame, along with the speed at which it spread – they did so at least as well as many commercially-available organohalogen flame retardants. And as an added benefit, the esters are less likely to migrate out of household products, plus they harmlessly decompose when left open to the elements.

The scientists have not yet determined the toxicity of the specific esters they've tested, although previous studies on similar compounds have indicated that they are "much less harmful than the corresponding organohalogens."

Source: American Chemical Society

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