Less than 10% of discarded plastic is recycled. This is one of the major reasons that plastic waste is such a threat to the environment. There are many challenges to recycling plastics. For one thing, there are many different types of plastic and if they are melted together, they tend to phase-separate like oil and water and the resultant substance is structurally weak. Sorting plastics by type is not a simple task. More generally, it is very difficult to produce plastic with its original properties from recycled feedstock. So recycled plastics generally end up being useful in only more limited applications.