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Bio-based melamine formaldehyde resins for flame-retardant polyurethane foams
Yixiang Wang1, Xiao Zheng1, Kaisen Jiang1
1Shandong Provincial Key Laboratory of Biochemical Engineering, College of Marine Science and Biological Engineering, Qingdao University of Science and Technology, Qingdao 266042, China.
International Journal of Biological Macromolecules
|June 4, 2024
Summary
Modified melamine formaldehyde additives significantly enhance rigid polyurethane foam properties. These flame retardants improve strength, thermal stability, and reduce smoke during combustion, offering superior performance over traditional methods.
Area of Science:
- Materials Science
- Polymer Chemistry
- Fire Safety Engineering
Background:
- Polyurethane (PU) foams are versatile materials whose properties can be tuned with additives.
- Melamine (MA) formaldehyde resin is known to improve flame retardancy in PU foams.
- Developing effective and functional flame retardants for PU is crucial for safety applications.
Purpose of the Study:
- To synthesize and evaluate novel modified melamine formaldehyde flame retardants for rigid PU foams.
- To investigate the impact of glycerol-modified (GMF), sodium alginate-modified (SGMF), and lignosulfonate-modified (LGMF) melamine formaldehyde on PU foam properties.
- To compare the flame-retardant and thermomechanical performance of these modified foams against unmodified PU and physically added MA.
Main Methods:
- Preparation of GMF, SGMF, and LGMF by chemical modification.
- Synthesis of rigid PU foams (GMF-PU, SGMF-PU, LGMF-PU) by reacting modified flame retardants with isocyanate.
- Characterization of thermomechanical properties (e.g., specific compression strength).
- Evaluation of flame-retardant properties using limiting oxygen index (LOI) and cone calorimetry.
Main Results:
- Modified melamine formaldehyde flame retardants significantly increased the specific compression strength of PU foams compared to physical addition and neat PU foam (PPU).
- Foam microstructure analysis revealed thicker cell walls and an increased closed-cell ratio.
- Sodium alginate and lignosulfonate modifications notably enhanced thermal stability.
- LOI and cone calorimetry demonstrated significantly improved flame-retardant efficiency for GMF-PU, SGMF-PU, and LGMF-PU.
- Reduced heat and smoke release were observed, with sodium alginate and lignosulfonate showing effectiveness in smoke suppression.
Conclusions:
- Chemically modified melamine formaldehyde resins serve as effective reactive flame retardants for rigid PU foams.
- Glycerol, sodium alginate, and lignosulfonate modifications enhance both mechanical and fire safety characteristics of PU foams.
- These novel flame retardants offer a promising route to developing safer and higher-performing polyurethane materials.
