Polystyrene (PS) is a common man’s plastics ...! It is a versatile thermoplastics resin and available in a wide range of formulations from General Purpose / Crystal PS which is transparent to Impact PS which is opaque / translucent in nature.

Various Grades of GPPS and HIPS are available and designed to be processed easily by different processing operations like, injection molding, extrusion & thermoforming, blow molding, foam sheet / board extrusion and bi-axially oriented sheet / film extrusion.

Versatile properties and ease of processing make polystyrene an extremely attractive material, capable of competing quite favourably with expensive resins in a number of demanding applications.

GPPS is a transparent, amorphous polymer, which exhibits high stiffness, good dimensional stability and electrical insulation properties etc. The commercial grades of crystal PS offer a wide range in melt flow index from 2 gm/10 min (ASTM D1238; 2000C/5kg) to as high as 30 gm/10 min with high-heat, high-molecular-weight versions.

The sparkling clarity of GPPS make it suitable for an extensive range of applications including molded food and non-food packaging, medical ware, household products, cassettes and CD jewel box, refrigerator inner parts and imitation jewelry, stationery, cutlery, hangers etc.

Commercial grades of HIPS are produced with addition of Polybutadiene rubber (PBR) for impact modification. The numbers of impact grades are available and these are generally classified as, medium impact PS (notched Izod values between 40 and 80 J/m), high impact PS (notched Izod values between 80 to 160 J/m) or super high impact PS (notched Izod value more than 160 J/m)

The mechanical properties of impact PS significantly depend on the rubber type, content and rubber morphology. Impact PS ranges from translucent to opaque in its natural color.
HIPS grades are widely used for food and non-food packaging, medical and house-ware products, TV cabinets, business machine and appliance parts, stationery, hangers etc.

Speciality Polystyrene is a value added product specifically designed for Appliance industry, XPS (extruded expanded foamed PS) insulation boards, OPS (Oriented PS) sheet etc.

Properties of normal grades of GPPS and HIPS are enhanced by use of special raw material, additives with state-of-the-art production techniques. Enhanced properties include, high molecular weight, super high impact strength, high heat resistance, high gloss and Environmental Stress Cracking Resistance (ESCR) etc.

Properties of polystyrene resin (GPPS / HIPS) are modified in compounding equipment with addition of additives to offer tailor made solutions for intended applications. Following properties of GPPS / HIPS resins can be modified by compounding operation:

• Colour
• Flammability
• Light Stability
• Mechanical Properties like Tensile Strength & Modulus, Impact etc.
• Thermal properties like heat resistance
• Electrical properties like glow wire temperature, resistivity etc.
• Optical properties like haze, transparency etc.
• Surface properties like COF, scratch resistance & gloss etc.

One of the above or more properties can also be modified at the same time.