**Varieties of Natural Rubber:**
– Amazonian rubber tree (Hevea brasiliensis)
– Congo rubber (Landolphia owariensis and L. spp.)
– Dandelion
– Other plants that produce latex rich in isoprene polymers
– Gum rubber term for tree-obtained natural rubber
**History and Pre–World War II Usage:**
– Indigenous Mesoamerican cultures first used rubber
– Rubber’s historical use by Maya, Aztec cultures, and its introduction to France
– Development of vulcanization by Charles Goodyear in 1839
– Rubber’s extensive pre–World War II use in various industries like automotive, textile, and manufacturing
**Properties and Elasticity of Rubber:**
– Unique physical and chemical properties of rubber
– Stress–strain behavior including the Mullins effect and the Payne effect
– Elasticity of rubber in its relaxed and stretched states
– Effects of vulcanization on rubber hardness and extensibility
**Production and Cultivation of Natural Rubber:**
– Global production statistics, with over 28 million tons produced in 2017
– Main natural rubber producers being Thailand, Indonesia, and Malaysia
– Economic life and cultivation considerations for rubber trees
– Latex extraction methods like rubber tapping and processing techniques
**Chemical Makeup, Molecular Structure, and Vulcanized Rubber:**
– Chemical composition of natural rubber and its thermoset nature after vulcanization
– Molecular structure of rubber as a natural polymer of isoprene
– Vulcanization process with sulfur, peroxide, or bisphenol additives
– Stabilization of rubber through vulcanization and formation of a 3-D matrix
**Transportation and Global Economics of Rubber:**
– Global transportation of natural rubber latex from Southeast Asia, South America, and Africa
– Concerns over future rubber supply due to plant diseases and climate change
– Impact of COVID-19 pandemic on rubber demand and prices
– Volatility in rubber prices affecting plantation investments and global economics
**Uses of Rubber:**
– Applications of uncured and vulcanized rubber in various industries
– Rubber’s flexibility in hoses, tires, and shock absorbers
– Impermeability of rubber in air hoses, balloons, and chemical tubing
– Resistance of rubber to water and chemicals for diverse applications.
Rubber, also called India rubber, latex, Amazonian rubber, caucho, or caoutchouc, as initially produced, consists of polymers of the organic compound isoprene, with minor impurities of other organic compounds. Thailand, Malaysia, Indonesia, and Cambodia are four of the leading rubber producers.
Types of polyisoprene that are used as natural rubbers are classified as elastomers.
Currently, rubber is harvested mainly in the form of the latex from the Pará rubber tree (Hevea brasiliensis) or others. The latex is a sticky, milky and white colloid drawn off by making incisions in the bark and collecting the fluid in vessels in a process called "tapping". The latex then is refined into the rubber that is ready for commercial processing. In major areas, latex is allowed to coagulate in the collection cup. The coagulated lumps are collected and processed into dry forms for sale.
Natural rubber is used extensively in many applications and products, either alone or in combination with other materials. In most of its useful forms, it has a large stretch ratio and high resilience and also is water-proof.[citation needed]
Industrial demand for rubber-like materials began to outstrip natural rubber supplies by the end of the 19th century, leading to the synthesis of synthetic rubber in 1909 by chemical means. [citation needed]