Materials

Sky domes can be fabricated of various materials, namely, of the cast acrylic Aglas (PMMA), the cast acrylic Aglas IRR (PMMA – IRR), the extruded acrylic (PMMA - XT), the solid polycarbonate (PC), the combination of the cast and the extruded acrylic, the combination of the polycarbonate and the cast or extruded acrylic.

Sky domes, made of the cast acrylic Aglas (PMMA - cast)

The sky domes Alux are most frequently fabricated of the cast acrylic glass Aglas, produced by Akripol. The sky domes are especially well-known for the following characteristics:

• long life time in spite of the exposure to the extreme weather conditions,
• excellent UV protection, preventing the altering of colour and yellowing (the cast acrylic Aglas is UV stabilized throughout the whole thickness, respectively, mass),
• there are no molten material dropping during burning and the fire does not spread.

The sky domes, made of the cast acrylic, provide the most favourable combination of the price of the sky dome, the choice of colours at one's option, and the life time of the sky dome.

Sky domes, made of the cast acrylic Aglas IRR (PMMA – IRR)

The Aglas IRR is a special kind of the cast acrylic Aglas, whose principal characteristics are the components, incorporated in its structure, having the capacity of the selective permeability of the visible part of the light on one hand, and the reflective capacity to thermal radiation (IR) on the other hand. The advantages of the sky domes, fabricated of the IRR acrylic Aglas, compared to the sky domes, made of the ordinary cast acrylic Aglas, result from the reflection of the light spectrum IRR at the transmission of the light through the sky dome:

• cost reduction of the heating of premises,
• cost reduction of the cooling (air-conditioning) of premises,
• increased comfort for the users of the room.

The acrylic sheets with the similar effect, produced by the majority of the competitive producers, contain the components with the reflective capacity to the light radiation incorporated only on the exterior surface, while the components, reflecting the light radiation, contained in the Aglas IRR, are incorporated in the material throughout the entire thickness, respectively the mass of the material. The acrylic sheets Aglas IRR are fabricated only in the opal colour.

Sky domes, made of the extruded acrylic (PMMA - XT)

Compared to the cast acrylic Aglas the chemical and physical properties of the extruded acrylic are substantially inferior to those of the cast acrylic. Owing to the poorer properties of the basic material, the quality of the sky domes, made of the extruded acrylic, is inferior to the quality of the sky domes, made of the cast acrylic Aglas, and their life time is shorter, too. Likewise, in the case of fire, the behaviour of the cast acrylic and of the extruded acrylic differs considerably – the extruded acrylic loses its toughness very quickly, becomes ragged, melts, and may be dropping during burning, while the cast acrylic becomes rubbery during burning, contracts, however, there is no dropping and spreading of fire over the place.

Sky domes, made of solid polycarbonate (PC)

The polycarbonate is a thermoplastic, fabricated by the process of extrusion. In appearance it resembles to acrylic. Compared to the acrylic, it has better performance properties in regard of the impact strength, toughness and hardness, however, its translucency is inferior to that of the acrylic, and its price is considerably higher than that of the acrylic, too. The performance properties of sky domes, made of polycarbonate, are better also in the case of fire: the polycarbonate is classed in the combustibility class B1, while the acrylic is put in B2.

Sky domes, made of the combination of the cast and the extruded acrylic glass

The sky domes, made of the combination of the cast and of the extruded acrylic, are fabricated thus that the exterior layer of the dome, exposed to the weather conditions, is made of the cast acrylic Aglas and the inner layers are made of the extruded acrylic.

The sky domes, made of polycarbonate and the cast or extruded acrylic

The sky domes, made of the combination of the solid polycarbonate and acrylic, are fabricated thus that one layer of the dome is made of the solid polycarbonate, and the other layers of the cast or extruded acrylic.

When the exterior layer is made of the solid polycarbonate, a sky dome has higher performance properties with regard to the exterior weather conditions due to the high performance of the polycarbonate (impact, hail, etc.)

The principal aim of the combination of the exterior layer, made of the cast or extruded acrylic, and the inner layer of the solid polycarbonate, is the amelioration of the fire safety properties of a sky dome (such a sky dome can be put in the B1 fire safety class).