Several manufacturers claim that some or all of the foams used in their mattresses are either partially or wholly made from plant oils. Terms used for these are soy foam, plant-based, botanical-oil, natural oils, etc. Plant oils used include those extracted from soy beans, castor beans, canola (rapeseed), palm kernel, coconut, peanuts, and other seeds. How are these oils used in making foam? And how does this affect the use of fossil fuel sources (petroleum and coal oil)?
Oil itself does not form foam, at least not the kind you can sleep on. Bedding and furniture foams, other than latex foam (foam rubber), are forms of polyurethane foam, a semi-rigid, flexible material which is both supportive and cushioning. Polyurethane is a polymer, chains of repeated links of molecules. These molecules are polyols, alcohols with several hydroxyl branches. An alcohol is an oil (hydrocarbon) which is partly oxidized. A hydroxyl is an -OH branch of oxygen and hydrogen.
Some polyols are always produced when refining petroleum. One plant oil, castor bean oil, contains a natural polyol. Most other plant oils have to be modifed to make polyols. The components of these oils are fatty acids, like mono-, di- and triglycerides, the precursors of cholesterol. The fatty acids used are long chains with a double carbon bond (C=C on a diagram) in the middle. Using ozone or other reactors, hydroxyls are added to the chains.
To make the polyurethane, the polyols are combined with isocyanates. The reactions form endless chains which cross-link to form the polyurethane. Gasses released by the reactions and air introduced during the process make the foam.
Until recently, only a small portion of petroleum in polyurethane foam could be replace by plant polyols (aka biopolyols) and still produce a quality foam. Refinement of the process, including using water for the solvent, make it possible to use a higher percentage of biopolyols. However, we need to carefully examine the claims of manufacturers and retailers in promoting their products. Don’t be afraid to ask what proportion of the oils used in making the foams are plant derived.
Use of polyols derived from natural plant oils reduces the use of petroleum in more than one way. First, it means less petroleum is used as the raw material. Second, this means less petroleum used as fuel for refining petroleum for polyols. Third, modifying plant oils requires less energy.
Other advantages of using plant polyols in manufacturing polyurethane and its derivative foams include 1) less or no VOCs (volatile organic compounds), and 2) less degradation of the foam by moisture (such as from sweat), and some plant-oil foams are less flammable.
However, use of plant oils has its own environmental concerns. First is land use for growing plant oil crops. Is the land chosen wisely? Or does it degrade natural resources (such as rain forests)? Second, are the farming practices environmentally acceptable? This includes preventing erosion and whether chemical pesticides, herbicides and fertilizers are used. Also, does raising and using plants for this purpose compete with food crops, thereby raising food prices?
In the final analysis, using natural plant oils to make polyurethane, memory foam, and other foams for bedding products is a net benefit for health, safety, and the environment. And this will grow as technological development improves the processes involved.
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