when different type of plastic are crush and mixed togerther is it possible to seperate them?
To a certain degree, it can be possible. Suppose that the plastic is turned into small bits. Different type of plastic may have slight variation in their density, so you can put them in a water bath, containing a variable concentration of salt. With pure water, then lpastic with a density less than 1 would float, and the ones with higher density wold sink. Then you take the plastic that sank and put in in a btah with slightly salted water, thus with a density slightly higher than 1, say 1.05. Then plastics with a density lower than 1.05 would float, the the heavier would sink, and so on. To separate lighter plastic, you can use a bath of oil, as oil has a density lower than water. But it gets quite complicated quickly, and costly unless you can do it on a large scale, and the plastic may not always be totally pure in the end. So recycled plastic will be used in applications that do not need perfectly controlled composition.
