Early polymer scientists studied natural polymers, such as DNA, RNA, polypeptides, and polysaccharides, but they did not immediately understand how the polymer’s chemical structure influenced behavior. For instance, in 1855, Alexander Parkes discovered that heated cellulose could be dissolved in a solvent and molded into various shapes. Once scientists understood polymeric structures, they invented synthetic methods for duplicating the molecular architecture. The majority of synthetic polymers of modern significance were patented and commercialized as part of the World War II effort. This initial growth was principally due to the commercialization of polymers for consumer packaging, specifically food packaging. Polymers had higher mechanical and environmental durability than paper but were not as expensive as glass and metal. Today, consumer packaging remains the largest use for polymers. Elastomers are sold as either one- or two-part chemistries. A one-part chemistry is purchased as a single package or canister from the manufacturer.