Production
En 2017 se produjeron más de 28 millones de toneladas de caucho, de las que aproximadamente el 47% eran naturales. Dado que la mayor parte es sintético, derivado del petróleo, el precio del caucho natural viene determinado, en gran medida, por el precio mundial del crudo.[31][32] Asia fue la principal fuente de caucho natural, con cerca del 90% de la producción en 2021.[33] Los tres mayores productores, Tailandia, Indonesia[34] y Malasia, suman alrededor del 72% de toda la producción de caucho natural. El caucho natural no se cultiva ampliamente en su continente natal, Sudamérica, debido al tizón foliar "Tizón (hongo)") sudamericano y a otros depredadores naturales.
Crop
Rubber latex is extracted from rubber trees. The economic life of rubber trees in plantations is about 32 years, with up to 7 years of immature phase and about 25 years of productive phase.
Soil requirements are well-drained, weathered soils composed of laterite, lateritic types, sedimentary types, non-lateritic or alluvial red soils.
The climatic conditions for the optimal growth of rubber trees are:.
• - 
Natural rubber sheets
Precipitation of about 250 centimeters distributed evenly without any marked dry season and with at least 100 days of rain a year.
• - The temperature ranges between 20 °C and 34 °C, with a monthly average of 25 °C to 28 °C.
• - Atmospheric humidity of around 80%.
• - About 2,000 hours of sunshine a year at a rate of six hours a day throughout the year.
• - Absence of strong winds.
Many high-yielding clones have been developed for commercial planting. These clones yield more than 2,000 kilograms per hectare (1,800 lb/acre) of dry rubber per year, under ideal conditions.
In places like Kerala and Sri Lanka, where coconuts are abundant, the half-shell of the coconut was used as a container to collect the latex. Glazed pottery or aluminum or plastic cups became more common in Kerala-India and other countries. The tops are supported by a wire that surrounds the tree. This wire incorporates a spring so that it can stretch as the tree grows. The latex is introduced into the cup using a galvanized "beak" that is struck against the bark. Latex extraction is usually done early in the morning, when the internal pressure of the tree is highest. A good hitter can hit a tree every 20 seconds with a standard half-spiral system, and the typical daily "task" size ranges from 450 to 650 trees. Trees are typically felled on alternate or third days, although many variations are used regarding the timing, length, and number of cuts. "The harvesters made a cut in the bark with a small hatchet. These oblique cuts allowed the latex to flow from the ducts located in the outer or inner layer of the bark (cambium) of the tree. Since the cambium controls the growth of the tree, it stops if it is cut. Thus, the extraction of rubber required precision, so that the incisions were not too many given the size of the tree, nor too deep, which could slow down its growth or kill him".[35].
It is common to knock a plank at least twice, sometimes three times, during the life of the tree. The economic life of the tree depends on how well the pruning is done, since the critical factor is bark consumption. In Malaysia, the norm for alternative daily harvest is a bark consumption of 25 cm (vertical) per year. The latex-containing tubes in the cortex spiral upward to the right. For this reason, chipping cuts often move up to the left to cut more tube. Trees drip latex for about four hours and stop when the latex naturally coagulates in the cut, thus blocking the latex tubes in the bark. The starters usually rest and eat after finishing their work and begin collecting the liquid "field latex" around midday.
The four types of field coagulation are: "cup clumps", "tree lace", "small farmers gum" and "soil residues". Each has significantly different properties.[36] Some trees continue to leak after harvesting, resulting in a small amount of "top clumps" that is harvested at the next harvest. The latex that coagulates in the cut is also collected as "tree lace." The lace on the tree and the crown lumps together represent between 10% and 20% of the dry rubber produced. The latex that falls to the ground, the "soil residue", is also periodically collected to process the low-quality product.
Crown clump is the coagulated material found in the collection crown when the collector revisits the tree to collect it. It comes from latex adhering to the walls of the canopy after the latex has been last poured into the bucket, and from latex exuded late before the tree's latex-carrying vessels become clogged. It is of greater purity and value than the other three types.
"Cup clumps" can also be used to describe a completely different type of coagulation that has accumulated in smallholder plantations over a period of 1 to 2 weeks. After uprooting all the trees, the collector returns to each one and adds some type of acid, allowing the newly collected latex to mix with the previously coagulated material. The mixture of rubber and acid is what gives rubber plantations, markets and factories a strong smell.
Tree lace is the strip of clot that the chopper peels from the previous cut before making a new cut. It usually contains more copper and manganese than the cup lump. Both copper and manganese are pro-oxidants and can damage the physical properties of dry rubber.
The rubber of the small owners is produced by them, who collect the rubber from trees far from the nearest factory. Many Indonesian smallholders, who cultivate rice fields in remote areas, knock down scattered trees on their way to work in the rice fields and collect the latex (or coagulated latex) on the way home. Since it is often impossible to preserve latex long enough to get it to a factory that will process it in time for it to be used in the production of high-quality products, and since the latex would have already coagulated by the time it reached the factory anyway, the small farmer will coagulate it by any means available, in any container available. Some small farmers use small containers, buckets, etc., but the latex often coagulates in holes in the ground, which are usually lined with plastic sheets. Acidic materials and fermented fruit juices are used to coagulate latex, a form of biologically assisted coagulation. Little care is taken to exclude twigs, leaves and even bark from the clumps that form, which may also include tree lace.
Soil debris is material that accumulates around the base of the tree. It comes from latex that overflows from the cut and runs down the bark, from rain that floods a collection cup containing latex, and from spills from collectors' buckets during collection. It contains dirt and other contaminants, and its rubber content varies depending on the amount of contaminants. The waste on the land is collected by field workers two or three times a year and can be cleaned in a scrap washer to recover the rubber, or sold to a contractor who cleans it and recovers the rubber. It is of low quality.
Prosecution
Latex coagulates in the cups if kept for a long time and must be collected before this happens. The collected latex, "field latex", is transferred to coagulation tanks for the preparation of dry rubber or transferred to airtight containers with sieving for ammoniation. Ammoniation, invented by patent attorney and vice president of the United States Rubber Company* Ernest Hopkinson around 1920, preserves latex in a colloidal state for longer periods of time. Latex is generally processed into latex concentrate for the manufacture of dip products or coagulated under clean, controlled conditions using formic acid. The coagulated latex can then be processed into block rubbers of higher quality and technical specification, such as SVR 3L or SVR CV, or used to produce fluted smoked sheets. Naturally coagulated rubber (cup lumps) is used in the manufacture of TSR10 and TSR20 grade rubbers. The processing of these qualities consists of a size reduction and a cleaning process to eliminate contamination and prepare the material for the final drying phase.[37].
The dry material is then baled and palletized for storage and shipping.
molecular structure
Rubber is a natural polymer of isoprene (polyisoprene) and an elastomer (elastic polymer). Polymers are simple chains of molecules that can join together. Rubber is one of the few natural polymers and is highly appreciated for its great elasticity, resistance and impermeability. Other examples of natural polymers are turtle shell, amber, and animal horn. When harvested, rubber takes the form of latex, an opaque, white, milky suspension of rubber particles in water. It is then transformed through industrial processes into the common solid form seen today.
Vulcanized rubber
Main article: Sulfur vulcanization.
Natural rubber is reactive and vulnerable to oxidation, but can be stabilized through a heating process called vulcanization. Vulcanization is a process by which rubber is heated and sulfur, peroxide or bisphenol is added to improve its resistance and elasticity and prevent it from rusting. Carbon black, which can come from an oil refinery or other natural incineration processes, is sometimes used as an additive to rubber to improve its resistance, especially in vehicle tires.[39][40].
During vulcanization, the rubber's polyisoprene molecules (long isoprene chains) are heated and cross-linked with molecular bonds to sulfur, forming a three-dimensional matrix. The optimal percentage of sulfur is approximately 10%. In this form, the orientation of the polyisoprene molecules remains random, but they align when the rubber is stretched. This vulcanization with sulfur makes the rubber stronger and more rigid, but it is still very elastic.[41] And through the vulcanization process, the sulfur and latex are intended to be fully utilized individually.
Transport
Natural rubber latex is shipped from factories in Southeast Asia, South America, and West and Central Africa to destinations around the world. Because the cost of natural rubber has risen sharply and rubber products are dense, shipping methods that offer the lowest cost per unit of weight are preferred. Depending on the destination, warehouse availability and transportation conditions, some methods are preferred by certain buyers. In international trade, latex rubber is primarily shipped in 20-foot sea containers. Inside the container, smaller containers are used to store the latex.[42].