There are two basic processes for HIPS production: intermittent process and continuous process. The two processes generally use prepolymerization first. After the completion of prepolymerization, the polymerization is continued in the form of suspension in the intermittent process and in the form of solution in the continuous process. Therefore, intermittent process is also called bulk suspension process, and continuous process is also called solution process.

Impact resistant polystyrene is an impact resistant polystyrene product produced by adding polybutadiene rubber particles to polystyrene. The polystyrene product will add micron sized rubber particles and connect the polystyrene and rubber particles together by branching. When impacted, the stress at the tip of crack propagation will be released by relatively soft rubber particles. Therefore, the crack propagation is hindered and the impact resistance is improved.