Plexiglass (or PMMA / polymethylmethacrylate) is more transparent than glass, polycarbonate and fiberglass, with a transparency coefficient pf 0,93. It is shock resistant, able to resist up to 12 Joules (per thickness of 4mm), resistant to atmospheric agents, to humidity, chemical agents and therefore it is used a lot for indoor fittings.
It is a flexible material that can be thermo-shaped but does not have the same level of unbreakability or of elasticity, as polycarbonate. Available in different colours and thicknesses (from 1 to 30 mm) it does however present some defects if exposed to outdoor environments: with time and sun radiation it tenders to discolour if not treated with anti UV additives, to harden and to crack, and in addition it gets easily scratched and therefore requires gentle cleaning.
It is however a material used for outdoor coverings, for exhibiting, window displays and requests with no special requirements.
In summary we can say:
Advantages of plexiglass:
Transparency
Resistance to chemical agents
Possibility to be shaped through thermoshaping
Personalisation by colours and thickness
Disadvantages of fiberglass compared with polycarbonate
Discolouration due to UV sun rays
Low shock-resistance
Gentle cleaning required
Low elasticity
Low fire reaction ability
High quality/price relationship
Advantages of polycarbonate:
Thermal and mechanical resistance
Toughness and Resistance
Load bearing and Wind pressure resistance
Lightness
Transparency
Ductility
Fire resistance
Thermal insulation
Recyclability and Ease of cleaning
Variable thickness