**3. Examination results and their analysis**

The determination of water absorption was conducted in accordance with DIN 53433 stan‐ dard. This method measures the hydrostatic buoyancy of the sample with the dimensions of

Thermo‐insulating properties of the produced foams were determined by measuring the heat conductivity coefficient *λ*. Samples with dimensions of 200 × 200 × 25 mm were used for the test. FOX 200 apparatus by Lasercomp was used during this examination. It enables the deter‐ mination of *λ*‐value in the range of 20–100 mW/(m K). The measurement chamber needs to be

The heat conductivity coefficient measurement method measures the amount of heat trans‐ ported through the sample material in a unit of time during the determined heat flow, that is, when the temperature difference is measured on the opposite sides of the examined sample.

Compressive strength was determined by the use of general‐purpose strength machine (Instron 5544). The peel and flanks of foam were cut off and the cubic samples were cut out (side of 50 ± 1 mm). Then, the samples were subjected to compressive strain by 10% according

The content of closed cells was determined in compliance with PN‐ISO 4590 standard, using defect‐free samples with the dimensions of 100 × 25 × 25 mm. The method utilizes the Boyle– Mariotte law. It determines a relative pressure decrease based on calibrated volume patterns, measuring the difference on the scale of a manometer with one arm opened to the atmosphere. The retention (remains after burning) of the PUR‐PIR foams was examined according to ASTM D3014‐73 standard, by performing the vertical test. The apparatus used for the burning examination using the vertical test had a vertical chimney with 300 × 57 × 54‐mm dimensions. Three of the walls were made out of tin and one was a removable glass wall. The test was con‐ ducted on six samples with dimensions of 150 × 19 × 19 mm. Before burning, the samples were weighted with an accuracy up to 0.0001 mm and placed inside the chimney. The glass was placed in place and flame was introduced to the samples from propane‐butane burner for 10 s. Then, the burner was moved away and the times of free burning and retention were measured

with a stopwatch in the vertical test. Retention was calculated using Eq. (1):

 = *m* \_\_\_ *m*0

Using the cone calorimeter, the examination of flame and smoke parameters was conducted for the produced PUR‐PIR foams based on the methodology described in the ISO 5660‐1:2001 norm. Normalized samples with dimensions of 100 × 100 mm were subjected to heat radiation. During the examination, the following parameters were recorded: the time needed to initi‐ ate the burning process, thermokinetic parameters, that is, heat exhaustion rate and the total amount of exhausted heat, and selected toxic and smokegenic properties. The thermokinetic

× 100% (1)

is the sample mass before burning (g), *m* is the sample mass after

150 × 150 × 25 mm, submerged in distilled water for 24 h.

The measurements are performed in series, in 0.5‐s intervals.

fully filled to conduct proper examination.

118 Aspects of Polyurethanes

to the direction of foam expansion.

*Re*

is the retention; *m*<sup>0</sup>

where *R*<sup>e</sup>

burning (g).
