Polymers 2021 , 13 , 709
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Table2. Ignition time and weight loss in samples with different thicknesses using heat fluxes of 40 to 50kW.m − 2 at a distance of 20 mm.
Density of Radiant Heat Flux (kW.m − 2 )
Thickness (mm)
Ignition Time (s) 107.4 ± 32.927 172.8 ± 68.271 170.0 ± 19.279 80.80 ± 14.372 108.0 ± 31.093 140.0 ± 31.698 86.4 ± 10.442 100.2 ± 21.673 111.2 ± 24.235 84.4 ± 9.002 93.4 ± 21.767 98.8 ± 12.592 67.08 ± 5.403 71.0 ± 8.671 103.6 ± 18.391 58.60 ± 5.953 63.40 ± 7.116 77.60 ± 25.881 62.20 ± 3.2497 63.20 ± 3.187 65.0 ± 11.436 56.80 ± 2.039 59.40 ± 5.607 60.20 ± 5.741
Weight Loss (%) 19.018 ± 0.742 16.528 ± 1.103 12.436 ± 0.402 20.188 ± 1.210 16.092 ± 0.885 13.256 ± 0.745 20.87 ± 0.889 17.026 ± 0.541 13.716 ± 0.303 21.868 ± 0.879 17.272 ± 0.647 13.504 ± 0.228 22.026 ± 0.908 17.5 ± 0.455 13.818 ± 0.266 23.206 ± 0.505 18.366 ± 0.910 14.222 ± 0.826 23.578 ± 0.858 18.764 ± 0.571 14.678 ± 0.899 24.302 ± 0.814 19.402 ± 0.586 14.846 ± 1.033
Corresponding Temperature ( ◦ C) 1
43
700
12 15 18 12 15 18 12 15 18 12 15 18 12 15 18 12 15 18 12 15 18 12 15 18
44
710
45
720
46
724
47
727
48
730
49
735
50
742
1 Based on the graphical dependence in Figure 3.
An interesting result is the reduction of time differences in individual thicknesses at higher heat fluxes. Heat fluxes of 49 and 50 kW.m − 2 offered almost equal times in all thicknesses. Differences in ignition times decreased with increasing heat flux, and the ignition differences between the individual thicknesses decreased. The maximum difference of ignition time between thicknesses (67.4 s) was at 43 kW.m − 2 and the minimum (3.4 s) was at 50 kW.m − 2 . It can therefore be concluded that with increasing heat flux value, the thickness of the OSB has no significant effect on the ignition time. The increase in weight loss was with increasing heat flux, namely in 12 mm by 5.3%, in 15 mm by 2.9% and in 18 mm by 2.41%. With increasing heat flux, there was an increase in weight loss of 12 mm by 5.3%, 15 mm by 2.9% and 18 mm by 2.41%. It is possible to make the following assumption: smaller thicknesses of OSB due to the increase of heat flow have more intensive thermod- egradation processes, which manifest in higher weight losses. Mitterov á and Garaj [32] studied the weight loss and ignition time of an OSB caused by the action of radiant heat. Test samples were exposed to an infrared heater with a power of 1000 W for 600 s, while the distance of the samples from the surface of the radiating body was 30 mm. The weight loss of the OSB reached 58.92%, and the ignition time was 53.4 s. In comparison with the values obtained by our research, the results are significantly different, because the distance between the emitters and the sample was relatively high, which affected the ignition time. The surprising result is more than 50% weight loss under these conditions. The use of one-way ANOVA confirms the significant dependence of the ignition time on the board thickness (Table 3, Figure 5). The ANOVA table decomposes the variance of Col_4: Time- to-ignition into two components: a between-group component and a within-group component. The F-ratio, which in this case equals 4.31448, is a ratio of the between-group estimate to the within-group estimate. Since the P-value of the F-test is less than 0.05, there is a statistically significant difference between the mean Col_4 from one level of Col_2 to another at the 5% significance level. To determine which means are significantly different from which others, select Multiple Range (Table 3).
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