Plasticizer is a kind of substance added to polymer system to increase its plasticity, improve its processability and improve the flexibility of products. In 1868, Hyatt used camphor as the plasticizer of nitrocellulose. It can be divided into internal plasticizer and external plasticizer according to its mode of action. The former refers to the introduction of a second monomer or a branch chain in the polymer chain during polymerization to reduce the regularity and crystallinity of the molecular chain and improve plasticity. Generally, it is only used in semi hard products; The latter is a kind of liquid with high boiling point that is difficult to volatilize or a solid with low melting point. Its main function is to weaken the secondary force (van der Waals force) between polymer molecules, enhance the movement of molecular bonds, reduce its crystallinity, so that the hardness, modulus, softening temperature and embrittlement temperature of the polymer decrease, while the elongation, flexibility and flexibility improve. According to different chemical structures, it can be divided into phthalates, aliphatic dibasic esters, phosphate esters, epoxy compounds, polyol esters, chlorinated plasticizers, oligomers, phenyl polyesters, petroleum esters and amides. There are more than 1000 kinds of products, and more than 200 kinds of goods have been consumed.
How about plasticizer pollution?
Phthalic acid esters in the air are adsorbed on the surface of particles as solid plasticizers or in the form of aerosols. Spraying paint, burning plastic dregs, and volatilization of plasticizer in agricultural film are the main ways for phthalates to enter the air. In factories where artificial leather and PVC film are consumed, the vapor concentration of phthalate esters in the air of workshops reaches 1. 7～66mg/m3。
The solubility of phthalic acid esters in water is higher than that of organic chlorinated hydrocarbons. The content of phthalic acid esters in rainwater solid plasticizer, river water and sea water in the industrial zone can be 10~1000 times higher than that of polychlorinated biphenyls.
They are either adsorbed on suspended particles or exist in a dissolved state. At present, the content of phthalic acid esters in air water in the world is generally PPb. (10-9 in the United States, France, etc., 10-12 in the United Kingdom, Germany, etc.) The content is relatively high in waters close to the industrial zone, such as the concentration of diisooctyl phthalate at the mouth of the Mississippi River in the United States reaches 0. six × 10-6. Phthalic acid esters in air water are very stable and difficult to synthesize, mainly from industrial and agricultural wastewater, surface runoff, and the sedimentation of particles in the air.
Phthalic acid esters in soil usually come from the deposition of industrial smoke. Sewage irrigation, accumulated plastic wastes, agricultural plastic films, etc. can seriously pollute part of the soil after being soaked by rainwater for a long time. For example, diisooctyl phthalate 0. twenty-three × 10-6. Dibutyl phthalate 1. one × 10-6。 Due to the precipitation of phthalic acid esters in water, the adsorption and exchange of sediment, the content of river sediment can accumulate to a relatively high level.
For example, 0% phthalate was detected in the sediment of the lower reaches of the Ohai River in the United States. 8%。 These phthalates can be released again when the water quality changes, showing a dynamic balance with the water content, and polluting benthos
