A by-product is a product derived from a manufacturing process, which is neither a product nor a residue. It is intentional and unavoidable, and is obtained at the same time as the main product.
A by-product can be of vegetable, mineral or other origin and can be reused, for example, in the plastics industry as a filler or even as the main component of a mixture.
The addition of by-products to plastics or bioplastics aims to improve their environmental footprint, while providing new functionalities and immediate product differentiation.