Natural rubber is a kind of polyisoprene as the main component of the natural polymer, the molecular formula is (c5h8) n,% ~ 94% in its composition is rubber hydrocarbon poly (isoprene), the rest of the protein, fatty acid, ash, carbohydrate, rubber material, natural rubber is the most widely used general-purpose rubber.
We usually say natural rubber is collected from Hevea brasiliensis latex, after solidification, drying process and made of elastic solid substance. Natural rubber is a kind of polyisoprene as the main component of the natural polymer, natural rubber
Natural rubber
Its rubber hydrocarbon (poly) content in more than 90%, but also contains a small amount of protein, fatty acids, sugar and ash.
Main use
Since natural rubber has a series of physical and chemical properties, especially its excellent resilience, insulation, vibration characteristics, water and plasticity and, after appropriate treatment also has oil resistance, acid resistance, alkali resistance, heat resistance, cold resistance, pressure resistance, wear resistance and other valuable properties, therefore, has been widely used for example. Daily use of rubbers, warm water bag, elastic band; the medical and health industry surgeon gloves, blood transfusion tube, a variety of condoms; tire transportation; transport industry use belt, conveyor belt, acid and alkali resistant gloves; irrigation hose, the agriculture meteorological measurement for ammonia water bag; balloons; seal, shockproof equipment used in scientific experiments; defense on the use of aircraft, tanks, artillery, gas masks; even the rocket and spacecraft, satellites and other sophisticated science and technology products cannot do without natural rubber.
Folding performance
Modern scientific research has proved that the ordinary natural rubber is the polymerization of the different.
(1) natural rubber chemical properties of natural rubber is unsaturated rubber and easily produce the vulcanization reaction (structured) reaction with curing agent, bromine and oxygen, ozone oxidation, cracking reaction, and halogen occurred chloride, reaction, in the catalyst and the role of acid occurred chemical reaction.
But due to the natural rubber is a polymer compound, so it has reaction characteristics of alkene class of organic compounds, such as slow response speed, incomplete reaction. Uneven, also has the coexistence of a variety of chemical reaction phenomena (such as oxidative cleavage reaction and structured reaction).
In natural rubber chemical reactions, the most important is the oxidative cleavage reaction and structured reaction. The former is rubber plastic compounding the theoretical basis, why folic acid rubber aging; the latter is rubber vulcanization processing of sulfide theoretical basis. And chlorinated natural rubber, ring, hydrogenation reaction, used in modification of natural rubber.
(2) natural rubber has excellent comprehensive mechanical properties of natural rubber at room temperature with good elasticity. This is due to the molecular chain of natural rubber at room temperature was amorphous state, molecular chain flexibility for a good reason. The density is 0.913g/cm, elastic modulus 2-4MPa about thirty percent of the iron and steel, and elongation is 300 times higher than that of iron and steel, maximum 10%. In the range of 0-100 degrees, the resilience of the natural rubber can be reached more than 50% - 80%.
(3) thermal aging of natural rubber at room temperature is high elastic body, the glass temperature is -72 degrees, slowly after the heat softening, in the 130-140 degrees began to flow, about 200 degrees began to decompose, 270 degrees violent decomposition.
Hydrofluoric acid (4) dielectric medium is refers to oil, liquid chemicals. Natural rubber intolerance cyclohexane, gasoline, benzene and other media, insoluble in polar acetone, ethanol, insoluble in water, resistance to 10%, 20% hydrochloric acid, sulfuric acid 30%, 50% sodium hydroxide. Not resistant to strong acid and strong oxidation of potassium permanganate, potassium.
(5) good processing properties of natural rubber because of high relative molecular mass, rather broad molecular weight distribution, molecular chain was easy to break, coupled with the rubber has a certain number of gelatin molecules, so it is easy to plastication, mixing, calendering, extruding, molding and so on.