Process for densification of low density polystyrene

A process for making a block of densified polymer material from expanded polymer material having a first direction, a second direction and a third direction relative thereto, said process comprising the steps of:

• compressing an expanded polymer material to a high density comprising the steps of:
• compressing said expanded polymer material in said first direction to a first intermediate density;
• compressing said expanded polymer material in said second direction to a second intermediate density;
• compressing said expanded polymer material in said third direction to a third density to form a block of densified material;
• maintaining said block of densified material an increased density substantially equal to said third density;
• degassing said block of densified material;
• maintaining a pressure of sufficient magnitude to induce substantial mechanical creep in said block of densified material;
• maintaining said pressure on said block of densified material for a preselected time corresponding to a permanent conformation of said block of densified material to substantially said increased density and corresponding to substantial cessation of said mechanical creep;
• and
• discharging said expanded polymer material as a densified polymer material, unrestrained in any dimension, to ambient, said densified polymer having substantially said increased density.