… derived from oils, in primary forms or in plates, sheets or strip; mixtures of any product of heading 40.01 with any … of this heading, in primary forms or in plates, sheets or strip. …
Explanatory notes
… The heading also covers synthetic rubber which has been treated for the purposes of transport and preservation or with a view to obtaining … use or to improve the qualities of the end product. Such treatment must not, however, alter its essential character …