They are considerably less dangerous to the ozone layer and have a short period of life in the atmosphere. In Europe, where a ban on the use of HCFC-agents for foaming xps apply either carbon dioxide (CO2) in its pure form, or CO2 in combination with hydrocarbons, alcohols, etc. Use of CO2 for frothing – technically difficult task that requires significant investments in reconstruction of existing production lines. Nevertheless, taking into account the global trend to reduce emissions of CFCs, ozone depleting Earth, this direction is very promising. Table.
1 compares the main va on effects on global warming. Global Warming Potential (GWP or GWP) – the coefficient, which was introduced in the Kyoto Protocol (1997). pgp allows equivalent comparison of different greenhouse gases in terms of their impact on global warming and / or duration of the atmosphere. As the standard adopted by the carbon dioxide: its gwp is one. Mechanisms responsible for heat transfer in plastic foams, including xps, are well known. By tradition, it is assumed that the thermal conductivity of xps board is made up of four components: the thermal conductivity of the solid phase material (polystyrene); thermal conductivity of the gas phase (BA); transmission of radiant energy, heat transfer by convection. In the case of xps, where the cell size is small (less than 2 mm), the convection component can be neglected. In the slabs of xps (as in any foam) heat transfer through the thermal conductivity of the solid phase and by radiation unchanging over time.