1,3,5-Trioxane, homopolymer (VAN) 31957-21-8 56940-47-7 56940-48-8 61673-96-9 9002-81-7 Formaldehyde polymer Formaldehyde, homopolymer NSC 28424 POLY(OXYMETHYLENE) Poly-s-trioxane Polyformaldehyde Polyoxymethylene Polytrioxane Takafest s-Trioxane, polymers