# The Ability to Control VOC Emissions from Multilayer Building Materials
## 3 Results and Discussion
The results of testing compounds emitted from the surface of samples W1 to W3 (Table 8) in conjunction with the results of testing the emissions from pure materials of liquid layers (Table 1) allow us to provide conclusions about the inhibition or slowing down of diffusion through the surface layers of the layered system. Comparing the emission profiles of different VOCs from sample W3 is shown in Figure 17, where the VOC concentration range is from 0 to 700 \(\upmu\)g/m\({}^{3}\). The parameters of the C(\(t\)) model (17) determined by numerical methods for the presented VOCs in Figure 17 are as follows: the parameter \(a\) is from 0.5 to 0.55, the parameter \(k_{1}\) is from 0.014 to 0.019 and the parameter \(k_{2}\) is from 0.003 to 0.004. Figure 16: The selected VOCs emission profiles from D1 floor systems (tested for 480 h) for the air change rates \(n=1\,\mathrm{h^{-1}}\) at 29 \({}^{\circ}\)C (and RH = 50% for both) in the emission test chamber, including butyl acetate, o-xylene and m-p-xylene (D1 sample is a floor system made of: polyurethane solvent primer and polyurethane adhesive). \begin{table}
\begin{tabular}{c c c c} \hline \hline  & **W1** & **W2** & **W3** \\ \hline \multirow{4}{*}{Ketones} & acetone & & \\  & 2-butanone & & \\  & 2-hexanone & & \\ \multirow{2}{*}{Alcohols} & butanol & ethanol & ethanol \\  & methyl acetate & & \\ \multirow{2}{*}{Esters} & ethyl acetate & & \\  & butyl acetate & butyl acetate & butyl acetate \\ \multirow{2}{*}{Hydrocarbons aromatic} & toluene & Toluene & Toluene \\  & ethylbenzene & & ethylbenzene \\ \multirow{2}{*}{Alcohols} & xylene & & o-xylene \\  & xylene & & m-p-xylene \\ \multirow{2}{*}{Esters} & limonene & limonene \\  & & 2-butanol & \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Main VOC compounds with the highest concentration detected by GCMS (W1–W3). Comparing the different VOCs' emission profiles from the W3 system for the different VOCs also shows quite similar chamber VOC concentration profiles with a concentration peak at some 20-30 h and an inflexion point at some 120-200 h. The course of butyl acetate is interesting and unique as the concentration drops sharply by 1/3 over time (after the maximum peak) only in 50 h.  
Notes on the Possible Comparison of the Emission Profiles of Both W and D Samples (the Same Selected VOCs)  
After testing, what VOC compounds emit products forming the coating (primer, waterproofing and adhesive) in various combinations described (Table 1) and what VOC compounds emit multilayer D-type samples (Table 7) and W-type samples (Table 8), four dominating compounds were selected whose emission profiles were compared at Table 9, assuming the values of the chamber concentration \(C_{max}\) (maximum concentration read from the time profile) and \(C_{480\,h}\) (concentrated emission after 480 h) as the emission measure (Sections 3.5 and 3.6). Three of the selected compounds, VOC ethylbenzene, butyl acetate and m-p-xylene, reached maximum emission levels \(C_{max}\) approximately four times the steady-state \(C_{480\,h}\). The emission level was determined in the range from 30 to 60 \(\mu\)g m\({}^{-3}\). One of the VOC emitting 1-butanol (samples D were tested at a lower temperature) has, however, a different emission profile; the \(C_{max}\) emission level of the sample type W is higher than that of type D, and the determined emission level of \(C_{480\,h}\) is not even twice as low as \(C_{max}\). It was found that some VOC contaminants are not ventilated just as easily, taking into account the concentration of other VOCs, their chemical structure, diffusion resistance through the layers and chemical and mechanical structure of the layers. The samples D1 and W3 selected in the first stage differ not only in the presence of waterproofing but also in the adhesive (polyurethane and epoxy) composition. Therefore, it is difficult to draw unambiguous conclusions from the comparison of the emission profiles given below.