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Almonds in Plastic Packaging? Are You Nuts?

August 24, 2018

Almonds taste great in cakes, breads, cereal, candy bars, even liquors.  Now there’s research going on that call for a plastics recipe which includes the tasty nut as filler.

Well, not the almond itself; more specifically, its shellAlmond shells enhance the strength of plastic more than most conventional materials and are being tested as a plastic filler replacement in all sorts of plastic products and packaging.

Traditional plastic fillers include calcium carbonate, talc and carbon black.  Almond shells  absolutely crush these fillers when it comes to costs, energy consumption, sustainability, biodegradability, even land-filling, if it came to that. But almond shells have a problem: they are hydrophilic, which, if you took Latin, you may have already deduced that they “love water.”  Or, put another way, they either absorb water, or are dissolved by it.  This is a definite issue in the plastic manufacturing process.

But there’s hope: when almond shells are “torrefied” (heated to 200-300 degrees in the absence of oxygen) , they become more hydrophobic which, again, if you took Latin,  would lead you to believe they would be more prone not to mix or dissolve in water.  What’s more, these heat-treated shells are more grind-able, lowering the costs of milling them down to size suitable for adding to plastic resin.

Experiments with adding almond shells to plastics have been carried out, with mixed results.  A composite known as TAS-PP (Torrefied Almond Shells -Polypropylene) increased the temperature where the composite softened and also its stiffness, but had lower tensile strength and elongation compared to pure polypropylene. Experiments with PE (polyethylene) have gone better, and materials scientists are optimistic about others.  Apparently, no one has worked enough with PET (polyethylene terephthalate) to know if almond shells would be a good filler for it or not.

The bottom line:  Using almond shell as a filler reduces the amount of petroleum-based plastic which needs to be produced for a given industrial application — a very green advantage.  TAS also reduce the amount of almond shells which need to be put in land fills (always a good thing) because it utilizes something that would be throw away anyway.  The problem is that large re-cyclers will not recycle this revolutonary composite material because they can only  can only tolerate a small non-plastic component in their recycling stream.

Simply put, if almond shells are going to be a major industrial plastic filler, recycling processes will need to be setup to accommodate the new materials.  And that’s not a very nutty idea at all.



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