The characteristics of EPS/HIPS/GPPS are compared.

• GPPS is general-purpose grade polystyrene,
  

The density of GPPS is 1.04~1.09, the transparency is as high as 88%~92%, and the refractive index is 1.59~1.60, so that the high refractive index makes it have a good luster, and has a decorative effect. Good dimensional stability. Common scope: Daily necessities: cups, various boxes, toothbrushes, combs, food containers, ballistics pens.

GPPS Features:

GPPS is colorless, odorless, odorless and lustrous, transparent particles, low cost, good coloring, stable size, transparent products, easy processing
The main determination of GPPS is that it is easy to break, low impact strength, poor heat resistance, can not withstand boiling water, can only be used at lower temperatures and lower loads, poor light resistance, flammable, black when burning with characteristic odor.

• HIPS are impact-resistant polystyrene,

It is a kind of impact-resistant polystyrene product produced by adding polybutyl rubber particles to polystyrene. HIPS is a modified material of PS, which contains 5-15% rubber components, and its toughness is about four times higher than PS, and the impact strength is greatly improved. It has the advantages of PS forming processing and strong coloring force. HPS has low water absorption and does not need to be pre-dried during processing. PS is a milky opaque pearl or particle, can be arbitrarily colored, good rigidity, easy processing molding, small strength than GPPS more than 7 times higher than the rubber content is different impact strength is also different, generally can be divided into impact resistance and ultra-high resistance to several grades. The tensile strength and transparency decrease with the increase of impact strength. Mainly used as packaging material, such as food
Products, cosmetics, daily necessities, mechanical instruments and stationery packaging, etc., can be formed by a variety of processing means.

HIPS Features:

HIPS for the milky white opaque pearl, with high impact and toughness, can be arbitrarily colored, molding processing
Impact grade polystyrene because it contains rubber components, its impact strength will be 5 to 10 times higher than GPPS, so that the application range of polystyrene has expanded, and it has replaced the expensive ABS material.

• ExpandedPolystyrene foam (EPS)
  

It is a lightweight polymer. It uses polystyrene resin to add foaming agent, at the same time heating to soften, produce gas, and form a rigid closed-cell structure of foam plastics. This uniform closed cavity structure makes EPS have the characteristics of low water absorption, good heat preservation, light weight and high mechanical strength. The density of EPS is determined by the expansion signal of polystyrene particles in the forming stage, which is generally between 10 and 45k/m3, and the apparent density of EPS used in engineering is generally 15 to 30k/m3. At present, the EPS density used as light fill in road engineering is 20k/m3, which is 1% to 2% of ordinary road fill. Density is an important index of EPS, and its mechanical properties are almost proportional to its density.