You mean as a source material to create the pellets that ultimately go into the molding machines? Well no, microplastics can't be recycled because they've broken down too much to make usable plastic.
No, the material has degraded too much to be of any use. Yes you can melt it into a pot of plastic but whatever comes out will be too brittle to be of practical use.
"Microplastic" describes a small pellet of plastic less than 5 mm in length. It doesn't refer to any specific type of chemical used to create plastic.
If the question is whether or not lego bricks generate microplastics, the answer is no, not really. Microplastics are mostly a problem when they wind up in the water supply, either from plastic fibers in clothes that are being washed, or plastic microbeads in shampoo that gets rinsed down the drain, or in plastic trash that has wound up in a river or ocean and is deteriorating into smaller particles.
4 mm is already considered microplastics? Wouldn't have guessed that. Almost as if the definition was "smaller than a 1x1 Lego plate" (which wouldn't be all that unreasonable I guess, it's the only system of units more commonly understood than the metric system)
