REKOMENDASI PENGGUNAAN HYDROXYL TERMINATED POLYBUTADIENE MADNIRI SEBAGI BINDER PROPELAN BERDASAR HASIL PENGUJIAN BERAT MOLEKUL HTPB IMPOR (RECOMENDATION OF USING THE AUTONOMOUS HYDROXYL TERMINATED POLYBUTADIENE AS BINDER FOR PROPELLANT BASED ON THE IMPOR HTPB MOLECULAR WEIGHT TESTING VALUES