This specification, which covers polystyrene materials, both crystal and rubber modified suitable for molding and extrusion, is intended to be a means of calling out plastic materials used in the fabrication of end items or parts. Polystyrene materials are classified according to classes after being grouped as crystal, rubber modified, and others. The materials are further classified according to grades after being grouped as general-purpose, other medium impact, high impact, super-high-impact, and others. The materials shall conform to the prescribed injection molded properties and natural colors.

1.1 This classification system covers polystyrene materials, both crystal and rubber modified, suitable for molding and extrusion.

1.2 This classification system and subsequent line callout (specification) are intended to be a means of calling out plastic materials used in the fabrication of end items or parts. It is not intended for the selection of materials. Material selection can be made by those having expertise in the plastics field after careful consideration of the design and the performance required of the part, the environment to which it will be exposed, the fabrication process to be employed, the inherent properties of the material other than those covered by this specification, and the economics.

1.3 The properties included in this specification are those required to identify the compositions covered. Other requirements necessary to identify particular characteristics important to specialized applications are to be specified using the suffixes as given in Section 5.

1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

Note 1: This standard combines elements from ISO 1622-1-2 and ISO 2897-1-2, but is not equivalent to either ISO standard.