Enhancing flame retardancy and water resistance in cellulose-based foams
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School of Engineering |
Master's thesis
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en
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92
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Abstract
The increasing threat of negative impacts of microplastics pollution created by petroleum-based foams led to the demand for more sustainable alternatives, such as cellulose-based foams (CBFs). However, these cellulose-based foams are inherently highly flammable and hydrophilic, restricting their scope in many applications. In addition, flame retardants used commercially are toxic to the environment and humans. Thus, minimizing this toxicity while enhancing the flame-retardant properties of cellulose-based foams was one of the aims of this thesis work. The other aim was to improve the hydrophobicity of these foams. In this study, four fire retardants (FRs), Epsom salt, precipitated calcium carbonate (PCC), borax, and diammonium phosphate (DAP), were used to enhance the flame-retardant property of a CBF. Foam blocks were manufactured with three concentrations of each fire retardant in the foam, including one sample with natural latex as a hydrophobic additive. These foams were also coated with beeswax as a hydrophobic coating. Scanning Electron Microscopy (SEM) was used for surface characterization, Fourier Transform Infrared Spectroscopy (FTIR) was used for the identification of functional groups in the foam, single-flame source test and thermogravimetric analysis (TGA) was used for analysis of their thermal behavior, and water column test (hydrostatic pressure test) was used to analyze the hydrophobicity of these foams with and without coatings. SEM results showed the accumulation of FR additives on the foams' surfaces, which were absent in the foam body (except PCC). A single-flame source test indicated that the PCC, DAP, and Borax slowed the flame propagation rate but eventually underwent complete combustion. However, Epsom salt was able to suppress the flame on the surface. TGA results of selected samples showed that Epsom salt had the highest residual mass at 900 $^o$C and operated at lower temperatures, while other FR additives worked at higher temperatures. A water column test revealed that adding latex helped maintain the foam's structural integrity even under high hydrostatic pressure, and beeswax coating successfully enhanced the hydrophobicity of these foams. Still, the presence of FRs did not significantly impact the hydrophobicity.Description
Supervisor
Bossuyt, SvenThesis advisor
Koivisto, JuhaViitanen, Leevi