Acrylonitrile-styrene-acrylic (ASA) terpolymer was blended with a sodium neutralized poly (ethylene-co-methacrylic acid) ionomer to develop a weather-resistant ASA with good heat sealing and adhesion properties. Both tensile strengths and modulus were reduced by about 45% with an increase in Na-ionomer concentration of 50%. The mechanical data were fitted with different models that predict mechanical behavior. The thermal stability was increased with the incorporation of ionomer. The temperature corresponding to 50% mass loss (T-m50) was increased from 400 degrees C (for ASA) to 427 degrees C for 50/50 ASA/Na-ionomer blend. SEM and AFM micrographs reveal the cone-shaped microstructure on the ASA matrix surface after a critical Na-ionomer concentration of 30%. This blend system follows typical non-Newtonian behavior. The heat sealing performance study with metal was also carried out to investigate the utilization of these blend systems as a protective layer for metal. POLYM. ENG. SCI., 55:1571-1579, 2015. (c) 2014 Society of Plastics Engineers