; pyridine, alkyl derivatives unspecified Subchapter II of chapter 99 is amended by inserting in numerical sequence the following new heading: 9902.10.51 Pyridine, alkyl derivatives (CAS No. 68391–11–7) (provided for in subheading 3824.99.28) Free No change No change On or before 12/31/2020 . 940. Polymeric ester blend Subchapter II of chapter 99 is amended by inserting in numerical sequence the following new heading: 9902.10.52 Mixtures of polymers based on tall oil fatty acids, phthalic anhydride, glycerin and rosin (CAS No. 68015–39–4); poly(isobutyl vinyl ether) (CAS No. 9003–44–5); zinc 2-ethylhexanoate (CAS No. 136–53–8)