What characteristic is essential for a material used in blow molding?

The essential characteristic for a material used in blow molding is good flow properties when heated. During the blow molding process, thermoplastic materials are heated until they become pliable and can be easily shaped. Good flow properties ensure that the material can be uniformly distributed within the mold, allowing it to accurately take on the desired shape. Materials that flow well when heated are critical for producing smooth and consistent products without defects.

Thermal stability is important in many applications, but it mainly relates to how a material behaves when exposed to temperature variations. While some thermal stability is necessary to prevent degradation during processing, it is not the primary concern in blow molding. The ability to expand and contract could relate to the thermal properties of materials but does not specifically reflect the requirements for ease of shaping during the molding process. High electrical conductivity is largely irrelevant in the context of blow molding, as it pertains to a material's ability to conduct electricity rather than its behavior in a heated, molded state.