The major types of polystyrene (PS) include general purpose polystyrene (GPPS), expanded polystyrene (EPS), extruded polystyrene (XPS), and the high impact polystyrene(HIPS). The last one is the strongest,among these types, but it is a graft copolymer with polybutadiene grafted on PS.

As homopolymer, PS is brittle & relatively fragile. It gets "tough" when styrene is copolymerized with other monomers. A copolymer (made of acrylonitrile, butadiene, and styrene) is called ABS resin. This terpolymer or copolymer is very strong & many calculators are made using it. Remember how many times the calculators of students fall from their desks to the ground, during exams, without getting broken or faulty ! ABS is the "champion" here.

Dear M. Ayaz,

The link below will be helpful:

https://www.creativemechanisms.com/blog/polystyrene-ps-plastic

Regards

Modestus

Read them

https://www.creativemechanisms.com/blog/polystyrene-ps-plastic

http://www.madehow.com/Volume-1/Expanded-Polystyrene-Foam-EPF.html