I’m going to talk a little bit about plant based resins and the newer push in the composites industry to work off of the petroleum bandwagon. There are a number of companies that have products on the market that are high quality laminating resins – take for instance pic to the left from a company called Easy Composites in the UK. This resin is not entirely from plants, they have blended in 35% plant based epoxy resin into their standard laminating resin as a start toward a 100% plant based epoxy laminating resin. They do this by using plant based Glycerol (glycerin alcohol) to make epichlorohydrin which is one of the major precursors for epoxies. And their Glycerol is made from plant based industrial waste products or are co-products of industrial processes. Most probably this is from the wood products industry or is made from plant waste material like corn stalks and other leafy waste that is usually either composted or discarded. That means that they have a nearly endless supply of raw material from which to make their plant-based resin.
Plant based resins can be made from nearly any plant based material, mostly because plants make long chain hydrocarbons – which we know as carbohydrates and oils. It is both the carbohydrates (sugars and longer chain polysaccharides) and the oils and fats that plants make that can be processed into bio-based composite resins. The two upper pics above are corn and sugar cane because some of the earliest and most successful bio-based resins comes from these stalks.
There is a great article in Composites World about bio-based resins from 2015 that is a good short read - https://www.compositesworld.com/articles/green-resins-closer-to-maturity. As it turns out, biomass can be fermented down into ethanol – yes the stuff that gets you drunk – which can be easily made into ethylene and then into polyethylene – bio-based plastic sheeting. Ethylene is one of the gases in natural gas, so making it from plants is far more sustainable. And of course, once you have ethylene, you have the two double bonded carbon atoms that make up the backbone of epoxy resins as well.
There are many other ways to get plant-based composite resins – especially epoxies because these are some of the most useful resins in the industry. There was a European Project (ECOxy - https://ecoxy.eu/ ) which had 13 partners and focused on the R&D necessary to convert all sorts of plant precursors into useful epoxy resins, along with several other composites sustainability goals. While that Project concluded in late 2020, one of their partners – Specific Polymers SP – wrote an article on that site that has a wonderful graphic (shown below) about making resin precursors from wood dust, algae, and vegetable oils.
Each of these three plant precursors can be easily processed into precursors for high performance epoxy resins. All of the partners in ECOxy focused on this business to produce bio-based, repairable, reprocessable, and recyclable composite materials.
In one of the next posts in this group on bio-based composites, I want to put the plant-based glues (resins) and the plant-based strings (fibers) together and talk about all natural String and Glue.
Comentarios