Short answers, pulled from the story.
Natural rubber consists of polymers of the organic compound isoprene, with minor impurities of other organic compounds. It is chemically cis-1,4-polyisoprene, with a molecular weight of 100,000 to 1,000,000 daltons. Up to 5 percent of its dry mass can be proteins, fatty acids, resins, and inorganic salts.
Most natural rubber is harvested as latex from the Amazonian rubber tree, Hevea brasiliensis, a member of the spurge family. Asia supplied about 90 percent of output in 2021, and Thailand, Indonesia, and Vietnam together produced around 61 percent of all natural rubber in 2022.
Natural rubber is harvested by tapping, in which a tapper makes a slanting slash in the bark to release latex from ducts in the inner bark. Tapping is done early in the morning when internal tree pressure is highest, and trees release latex for about four hours before the flow coagulates and stops.
The high price of natural rubber drove forced labor and brutal quota enforcement. In the Congo Free State, King Leopold II's state removed the hands of victims as proof of killings, and in the Amazon, the Putumayo genocide under Julio César Arana captured or killed many indigenous people between the 1880s and 1913.
Relaxed rubber is a disorganized cluster of wrinkled chains, and when stretched the chains become almost linear. The restoring force comes from the dominance of wrinkled conformations over linear ones, and vulcanization adds sulfide bonds that make the rubber harder and tighten more quickly under strain.
Charles Marie de La Condamine is credited with introducing rubber samples to the Académie Royale des Sciences of France in 1736, writing the word as caoutchouc. The English name rubber came from Joseph Priestley, who observed in 1770 that the material was good for rubbing pencil marks off paper.
Some people have a serious latex allergy, and exposure to products like latex gloves can cause anaphylactic shock. Vulcanization reduces the antigenic proteins in Hevea latex by about 99.9 percent but does not eliminate them, while latex from non-Hevea sources such as guayule can be used without allergic reaction.