how rubber is made?

Rubber is a kind of high elastic polymer material with reversible deformation. It is elastic at room temperature and can produce large deformation under small external force.Rubber is a completely amorphous polymer with a low vitrified transition temperature (T g) and a high molecular weight of more than hundreds of thousands.
Early rubber was made from rubber latex from plants such as rubber trees and grass, which was made of flexible, insulative, impervious to water and air.High elastic polymer compound.It is divided into natural rubber and synthetic rubber.Natural rubber is made from rubber tree, rubber grass, etc.Synthetic rubber is produced by polymerization of various monomers.Rubber products are widely used in industry and life.

The word rubber comes from the Indian ucau chu, meaning "the weeping tree."Natural rubber is made from rubber latex which flows out of the rubber tree when it is cut by three-leaf rubber tree after solidification and drying.In 1770, the British chemist j. Priestley discovered that rubber could be used to erase pencil marks.The molecular chain of rubber can be crosslinked. When the rubber is deformed by external forces, it has the ability to recover quickly and has good physical and mechanical properties and chemical stability.Rubber is the basic material of the rubber industry and is widely used in the manufacture of tires, rubber pipes, tape, cables and other rubber products.

Natural rubber is made from latex, and some of the non-rubber ingredients in latex are left in solid natural rubber.In general, the rubber hydrocarbon in natural rubber is 92% to 95%, while the non-rubber hydrocarbon accounts for 5% to 8%.Due to different preparation methods, different producing areas and even different season of glue collection, the proportion of these ingredients may be different, but they are basically within the range.
Protein can promote the vulcanization of rubber and delay the aging.On the other hand, protein has strong water absorption, can cause the rubber moisture absorption mildew, the decline of insulation, protein also has the disadvantage of increasing the heat generation.
Acetone extract is senior fatty acids and sterols substances, including some role natural protective agent and accelerator, and can help powder compound in the process of mixing dispersion and raw rubber softening effect.
In the ash mainly containing magnesium phosphate and calcium phosphate salts, have a very small amount of copper, manganese, iron and other metal compounds, because the base metal ions can promote the rubber aging, so their content should be controlled.

Moisture in the dry glue not more than 1%, in the process of machining can be volatile, but when moisture content is too much, not only can make the rubber easy mold storage process, but also affects the rubber processing, such as mixed compound easy cluster;Bubbles are easy to be produced in the process of calendering and pressing, and bubbles or spongy are produced in the process of vulcanizing.

The History of Synthetic Rubber ①

Humans have been using natural rubber for centuries.Columbus discovered on the voyage of the new world that a ball of native American play was made with a hardened plant SAP.Columbus and later explorers were all amazed at this bouncy ball.Some samples were taken back to Europe as curiosities.It was later discovered that the elastic ball could erase the marks of the pencil and gave it a common name, "rubber."This is still the name of the substance at the moment.This substance is rubber.

But it wasn't until 1839, when Charles Goodyear, an American, succeeded in vulcanization of natural rubber, that rubber became a useful material.The crosslinking of rubber chain is achieved by heating with sulfur, which makes the rubber have good elasticity.Why is rubber elastic?Let's analyze the molecular structure of rubber.The chain monomer of natural rubber molecule is isoprene.We know that the molecular force between the chain and the chain determines its physical properties.In rubber, the interaction between the molecules is weak, because it is not easy to interact with other chains.It's like two friends trying to shake hands, but everyone has a lot of things on their hands, so it's hard to shake hands.The force between rubber molecules determines the flexibility of the rubber.The molecules of rubber are easy to rotate and have ample space for movement, and the arrangement of molecules presents an irregular and random natural state.When subjected to external influences such as bending and elongation, the molecules are forced to show certain regularity.When the outside force is removed, the rubber molecules return to their original irregular state.This is why rubber is elastic.Because of the weak intermolecular force, the molecules can rotate freely, and there is not enough coupling between the molecular chains. Therefore, the molecules will slide between each other and the elastic will not show up.This slip is reduced by intermolecular entanglement.However, the intermolecular entanglement is unstable, and as the temperature increases or the winding of the time is loosened, it is necessary to establish a stronger connection between the molecular chains.This is the cure that Goodyear invented.The vulcanization process usually takes place at a temperature of 140 to 150 degrees Celsius.Goodyear's little stove was heating up.The main effect of vulcanization is simply to form a crosslink between the molecular chain and the molecular chain, thereby enhancing the interaction between the molecular chains.


to be continue...

How are synthetic rubbers made？

Synthetic rubber is a highly elastic polymer synthesized by artificial synthesis. Also known as synthetic elastomers, it is one of the three major synthetic materials that yield just below synthetic resins (or plastics) and synthetic fibers. The classification methods are diverse, the development has a long history, and has broad research prospect.

The process of forming rubber products.Liquid  Silicone rubber
It can be divided into thermoplastic rubber (such as the tri-block thermoplastic styrene rubber) and vulcanized rubber (which can be produced by vulcanization, most of which are made of synthetic rubber).
Other non-rubber components of raw gum: oil - filled parent glue, carbon black glue and lignin.

Performance by use
It is divided into general type rubber and special rubber.Refers to general-purpose rubber can replace natural rubber part or all of the use of rubber, such as styrene butadiene rubber, isoprene rubber, butadiene rubber, etc., mainly used in the manufacture of all kinds of tires and general industrial rubber products.The demand of general rubber is large, which is the main variety of synthetic rubber.
Rubber is a special high temperature resistant, oil resistant, resistant to ozone, ageing resistance and high air tightness and other characteristics of the rubber, commonly used with silicone rubber, fluorine rubber, polysulfide rubber, chlorohydrin rubber, nitrile rubber and polyacrylate rubber, polyurethane rubber and butyl rubber, mainly used for special occasions require certain properties.

Important varieties have styrene-butadiene rubber, nitrile rubber, butyl rubber, neoprene, polysulfide rubber, polyurethane rubber, acrylate rubber, chlorosulfonated polyethylene rubber, silicone rubber, fluorine rubber, butadiene rubber, isoprene rubber and ethylene propylene rubber, etc.