Natural rubber natural properties introduction

　　Generally speaking, natural rubber refers to an elastic solid made from natural rubber latex collected from Brazilian rubber trees and processed by solidification and drying. Natural rubber is a natural polymer compound with cis-1,4-polyisoprene as its main component. Its molecular formula is (C5H8)n, and its rubber hydrocarbon (cis-1,4-polyisoprene) content. At least 90%, it also contains a small amount of protein, fatty acids, sugar and ash.

　　The physical properties of natural rubber. Natural rubber has high elasticity at room temperature, slightly plasticity, very good mechanical strength, low hysteresis loss, low heat generation during multiple deformations, so its flex resistance is also good, and because it is non-polar Rubber, so electrical insulation performance is good.

　　The chemical properties of natural rubber. Because of the unsaturated double bonds, natural rubber is a chemically reactive substance. Light, heat, ozone, radiation, flexural deformation and metals such as copper and manganese can promote the aging of rubber. The achilles heel of rubber, however, the natural rubber added with anti-aging agent, sometimes can not see much change after exposure for two months in the sun, can still be used as usual after storage in the warehouse for three years.

　　The dielectric properties of natural rubber. Natural rubber has good alkali resistance, but it is not resistant to strong acid. Since natural rubber is a non-polar rubber, it can only resist some polar solvents and swells in non-polar solvents. Therefore, its oil resistance and solvent resistance are poor. Generally speaking, hydrocarbons, halogenated hydrocarbons, carbon disulfide, ethers Higher ketones and higher fatty acids have a solubility in natural rubber, but their solubility is affected by the degree of plasticization, while lower ketones, lower esters and alcohols are non-solvents for natural rubber.

　　Natural rubber microstructure

　　The structure of natural rubber is mainly the chain structure of macromolecules, molecular weight and its distribution and aggregation structure. The macromolecular chain structural unit of natural rubber is isoprene, and the macromolecular chain is mainly composed of polyisoolefin. More than 97%, there are aldehyde groups in the molecular chain, and there is one on each macromolecular chain. It is the aldehyde group that undergoes condensation or reacts with protein decomposition products to form branching and cross-linking, making rubber The viscosity increases during storage, and the natural rubber macromolecular chain also has an epoxy group, which is relatively active.

　　The macromolecular end of the natural rubber is generally inferred to be dimethylallyl, the other end is a pyrophosphate group, the terminal group, the aldehyde group of the molecular chain, and the polymerized element are few, in terms of the molecular weight and distribution of the natural rubber, The molecular weight range is wide. According to foreign reports, most of the molecular weight is about 30,000. Natural rubber, rubber, and vulcanizate have relatively high strength. Generally, the natural rubber strength can reach three megapascals.

　　The main reason for the high mechanical strength of natural rubber is that it is a self-reinforcing rubber series. When stretched, the macromolecular chain will be oriented along the stress direction to form crystals. The crystal grains will be reinforced by amorphous macromolecules without expansion. The reason for the same high strength is the close agglomeration of tiny particles in its internal structure.