Is polypropylene reuseable

Answer 1

In general, Yes.

Actually majority of lunch boxes are made of polypropylene.

Basically, Polypropylene can be reused in same application as long it is still usable (ie. Clean, non broken, etc.)

However, there is polypropylene with specific additive that is not intended for food contact applications (ex. Plastic paint pail) which is not suitable to be reused in other food contact applications.