Rubber refers to a high-elastic polymer material with reversible deformation, which is elastic at room temperature, can produce large deformation under a small external force, and can be restored after removing the external force.Rubber is a completely amorphous polymer, and its glass transition temperature (T g) is low, and its molecular weight is often large, more than several hundred thousand.
The early rubber is from rubber trees, rubber grass and other plants of latex, after processing made elastic, insulative, waterproof and air materials.High elastic polymer.It is divided into natural rubber and synthetic rubber.Natural rubber is made from rubber tree, rubber grass and other plants.Synthetic rubber is obtained by polymerization of various monomers.Rubber products are widely used in industry and life
The word rubber comes from the Indian word cau-uchu, meaning "tree in tears."Natural rubber is made by solidifying and drying the latex which flows out from the rubber cutting.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 deforms under the action of external forces, it has the ability of rapid recovery and has good physical and mechanical properties and chemical stability.Rubber is the basic raw material of the rubber industry, widely used in the manufacture of tires, rubber tubes, tapes, cables and other rubber products.
Trefoil rubber trees provide the most commercial rubber.When it is injured (such as when the bark of the stem is cut), it produces a lot of SAP containing latex rubber.
Also, figs and some euphorbia plants provide rubber.Germany tried to obtain rubber from these plants when its supply was cut off during the second world war, but later switched to making artificial rubber.
The first rubber trees were grown in South America, but they have been planted artificially, and there are abundant rubber trees in southeast Asia.In fact, Asia has become the most important source of rubber.
Rubber made from stevia can reduce sensitivity
Natural rubber is made from latex, which contains some of the non-rubber components left in solid natural rubber.Natural rubber generally contains 92%-95% rubber hydrocarbon, and non-rubber hydrocarbon accounts for 5%-8%.The proportion of these ingredients may be different due to different manufacturing methods, different producing areas and even different rubber harvesting seasons, but they are basically within the range.
Protein can promote vulcanization of rubber and delay aging.On the other hand, protein has stronger water absorption, can cause rubber moisture absorption mildew, insulation drop, protein still has the shortcoming that increases heat generation.
Acetone extract is some of the higher fatty acids and sterols, some of which act as natural anti-aging agents and promoters, and can help the powder complexes disperse in the mixing process and play a softening role on the raw glue.
The ash mainly contains salts such as magnesium phosphate and calcium phosphate, and there are very small amounts of metal compounds such as copper, manganese and iron. As these changed metal ions can promote rubber aging, their content should be controlled.
The moisture in dry glue does not exceed 1%, can volatilize in processing process, but when moisture content is too much, not only can make the mildew in raw glue storage process, but also can affect the processing of rubber, such as mixing agent easy to form a group;Bubbles are easily produced during calendering and extrusion, and bubbles or spongy form are produced during curing.
It can be divided into block rubber, latex, liquid rubber and powder rubber.milk rubber,rubber
Colloidal moisture dispersions of rubber;Liquid rubber is an oligomer of rubber, generally a viscous liquid before vulcanization;Powder rubber is made from latex into powder to facilitate mixing and processing.Thermoplastic rubber, developed in the 1960s, is formed by thermoplastic processing instead of chemical vulcanization.Rubber is divided into general type and special type by use.It is an insulator and does not conduct electricity easily, but it may become a conductor if it is soaked in water or at different temperatures.Conduction is the ease of conduction of electrons within a substance's molecules or ions.By raw material source and method: rubber can be divided into natural rubber and synthetic rubber.Among them, natural rubber accounts for 1/3, and synthetic rubber accounts for 2/3.
According to the appearance of rubber: rubber can be divided into solid rubber (also known as dry rubber), emulsion rubber (latex for short), liquid rubber and powder rubber four categories.
According to the properties and USES of rubber: in addition to natural rubber, synthetic rubber can be divided into general synthetic rubber, semi-general synthetic rubber, special synthetic rubber and special synthetic rubber.
According to the physical form of rubber: rubber can be divided into hard and soft rubber, raw rubber and mixed rubber.
According to performance and use: general rubber and special rubber.
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