Plastic flotation is mainly for the sorting of waste plastics with similar density and similar charging properties. For the sorting of common plastics PE, PVC, PP, PS, PET, aBS, PMMa, PC, POM, Pa, etc., plastics Flotation usually refers to the separation of waste mixtures such as PVC, PVC/PET, PVC/PC/POM, and aBS/PC/PS/Pa.
The principle of flotation separation is based on the selection and fixation of the particles to be separated. In the natural state, most of the plastics are hydrophobic and can float. Therefore, in order to realize the flotation separation of plastics, it is necessary to separate the particles to be separated. The components are selectively wettable. Plastic flotation methods can be roughly divided into three categories: 7 flotation, physical regulation flotation and chemical regulation. Take factory flotation as an example for explanation.
Different plastics have different wetting critical surface tensions (or surface free energy) γC. For plastic flotation, the meaning of γC is: when the surface tension of a liquid is γL>γC, the plastic will not be wetted by the liquid and remain hydrophobic and floatable; when γL<γC, the plastic is wetted by the liquid. And is suppressed. When the relationship between γL and the wetting critical surface tension γC1, γC2 of the two plastics satisfies the relationship of γC1 < γL < γC2, the plastic 2 will be wetted by the liquid, and the plastic 1 will float, thereby achieving γ flotation separation of the plastic. The γC values ​​of some plastics are listed in the table, and the figure shows the flow chart of the flotation process. γC value of the plastic part of the watch (20 ° C)
Plastic PVCPETPP PEPSPCPOMPMMaPa66
γC 39 46 293133 39 26 39 46
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