| 摘要 |
Absorbing compsn. for sound waves comprising: (a) a structural material (I) imparting limited rigidity to the compsn.; and (b) an absorbing material (II) having a lesser rigidity than the compsn. in order to dissipate the sound wave energy; is characterised in that (I) is a thixotropic material constituted by macromolecules (III) carrying electric charges of a same sign and having no mutual covalent bonds, the electric charges being neutralised by small and mobile counter ions. Pref. (I) is a plastic porous material impregnated with the thixotropic material. At least part of the counter ions carry hydroxyl groups allowing hydrogen bonding. (III) is (i) an acid polymer, such as polyacrylic acid, polystyrenesulphonic acid and carboxycellulose, the counter ions being derived from organic bases, such as ammonia, aminoalcohols (mono-, di- or tri-ethanol amine) and quat. ammoniums; or (ii) a basic polymer, such as polyethylene-imine, the counter ions being derived from carboxylic acids, such as citric acid, propionic acid, glycolic acid and sebacic acid, sulphonic acids or phosphonic acids. |
