Compositions of organic acid modified ionomers filled with silica

A filled thermoplastic composition comprising an organic acid-modified ionomer and a silica filler wherein

• the organic acid-modified ionomer comprises or is produced from an ethylene acid copolymer and an organic acid or salt thereof;
• the ethylene acid copolymer comprises copolymerized units of ethylene, copolymerized units of a C3-8 α,β-ethylenically unsaturated carboxylic acid, and optionally copolymerized units of a softening comonomer selected from the group consisting of vinyl acetate, alkyl acrylate and alkyl methacrylate;
• the organic acid comprises at least one aliphatic, monofunctional organic acid having 4 to 36 carbon atoms;
• the combined acid moieties in the acid copolymer and the organic acid are nominally neutralized to a level from about 70% to about 100%;
• and
• the silica filler has an oil absorption greater than 250 g oil/100 g silica, as determined according to ASTM D1483-95.