One of the biggest disadvantages of rigid polyurethane (PU) foams is its low thermal resistance, high flammability and high smoke production. Greatest advantage of this thermal insulation material is its low thermal conductivity (λ), which at 18-28 mW/(m•K) is superior to other materials. To lower the flammability of PU foams, different flame retardants (FR) are used. Usually, industrially viable are halogenated liquid FRs but recent trends in EU regulations show that they are not desirable any more. Main concern is toxicity of smoke and health hazard form volatiles in PU foam materials. Development of intumescent passive fire protection for foam materials would answer problems with flammability without using halogenated FRs. It is possible to add expandable graphite (EG) into PU foam structure but this increases the thermal conductivity greatly. Thus, the main advantage of PU foam is lost. To decrease the flammability of PU foams, three different contents 3%; 9% and 15% of EG were added to PU foam formulation. Sample with 15% of EG increased λ of PU foam from 24.0 to 30.0 mW/(m•K). This paper describes the study where PU foam developed from renewable resources is protected with thermally expandable intumescent mat from Technical Fibre Products Ltd. (TFP) as an alternative to EG added into PU material. TFP produces range of mineral fibre mats with EG that produce passive fire barrier. Two type mats were used to develop sandwich-type PU foams. Also, synergy effect of non-halogenated FR, dimethyl propyl phosphate and EG was studied. Flammability of developed materials was assessed using Cone Calorimeter equipment. Density, thermal conductivity, compression strength and modulus of elasticity were tested for developed PU foams. PU foam morphology was assessed from scanning electron microscopy images.
 Silva M.C., Takahashi J.A., Chaussy D., Belgacem M.N., Silva G.G. (2010). Composites of rigid polyurethane foam and cellulose residue. Journal of Applied Polymer Science, 117, 3665-3672.
 Stirna U., Beverte I., Yakushin V., Cabulis U. (2011). Mechanical properties of rigid polyurethane foams at room and cryogenic temperatures. Journal of Cellular Plastics, 47(4), 337-355.
 Zatorski W., Brzozowski Z.K., Kolbrecki A. (2008). New developments in chemical modification of fire-safe rigid polyurethane foams. Polymer Degradation and Stability, 93(11), 2071-2076.
 Zhang L., Zhang M., Yonghong Z., Hu L. (2013). The study of mechanical behavior and flame retardancy of castor oil phosphate-based rigid polyurethane foam composites containing expanded graphite and triethyl phosphate. Polymer Degradation and Stability, 98(12), 2784-2794.
 Cullis C.F.,Hirschler M.M. (1981). The Combustion of Organic Polymers. Clarendon Press (Oxford).
 Weil E.D., Ravey M., Gertner D. (1996). Recent progress in flame retardancy of polyurethane foams. In Proceedings of the Conference on Recent Advances in Flame Retardancy of Polymeric Materials, Stamford, CT, 191-200.
 Czuprynski B., Paciorek-Sadowska J., Liszkowska J. (2002). The effect of tri(1-chloro-3-etoxy-propane-2-ol) borate on the properties of rigid polyurethanepolyisocyanurate foams. Polimery, 10, 727.
 Hill K. (2000). Fats and oils as oleochemical raw materials. Pure and Applied Chemistry, 72(7), 1255-1264.
 Montero de Espinosa L., Meier M.A.R. (2011). Plant oils: the perfect renewable resource for polymer science. European Polymer Journal, 47(5), 837-852.
 Williams C.K., Hillmyer M.A. (2008). Polymers from renewable resources: a perspective for a special issue of polymer reviews. Polymer Reviews, 48(1), 1-10.
 Gandini A. (2008). Polymers from renewable resources: a challenge for the future of macromolecular materials. Macromolecules, 41(24), 9491-9504.
 Van Haveren J., Scott E.L., Sanders J. (2008). Bulk chemicals from biomass. Biofuels, Bioproducts and Biorefining, 2(1), 41-57.
 Cabulis U., Kirpluks M., Stirna U., Lopez M.J., Vargas- Garcia M.C., et al. (2012). Rigid polyurethane foams obtained from tall oil and filled with natural fibers: Application as a support for immobilization of lignindegrading microorganisms. Journal of Cellular Plastics, 48(6), 500-515.
 Feske E.F., Brown W.R. (2002). Flame Retardant Pentane Blown Polyisocyanurate Foams for Roofing. In Proceedings of Polyurethanes EXPO 2002, Salt Lake City, UT, 32-40.
 Levchik S.V., Weil E.D. (2004). Thermal decomposition, combustion and fire-retardancy of polyurethanes-a review of the recent literature. Polymer International, 53, 1585-1610.
 Modesti M., Lorenzetti A., Simioni F., Checchin M. (2001). Influence of different flame retardants on fire behaviour of modified PIR/PUR polymers. Polymer Degradation and Stability, 74(3), 475-479.
 Camino G., Luda M.P., Costa L. (1993). In Proceedings of Chemical industry and environment. Barcelona, Universitat Politecnica de Catalunja, 221-227.
 Fire classification of construction products and building elements - Part 1: Classification using test data from reaction to fire tests, EN 13501-1+A1
 Modesti M., Lorenzetti A., Simioni F., Camino G. (2002). Expandable graphite as an intumescent flame retardant in polyisocyanurate-polyurethane foams. Polymer Degradation and Stability, 77 (2), 195-202.
 Xie R.C., Qu B.J. (2001). Expandable graphite systems for halogen-free flame retardant of polyolefins. I. Flammability characterization and synergistic effect. Journal of Applied Polymer Science, 80(8), 1181-1189.
 Duquesne S., Delobel R., Michel L.B., Camino G. (2002). A comparative study of the mechanism of action of ammonium polyphosphate and expandable graphite in polyurethane. Polymer Degradation and Stability, 77(2), 333-344.
 Gao L., Zheng G., Zhou Y., Hu L., Feng G., Zhang M. (2014). Synergistic effect of expandable graphite, diethyl ethylphosphonate and organically-modified layered double hydroxide on flame retardancy and fire behavior of polyisocyanurate-polyurethane foam nanocomposite. Polymer Degradation and Stability, 101, 92-101.
 Feng F., Qian L. (2013). The flame retardant behaviors and synergistic effect of expandable graphite and dimethyl methylphosphonate in rigid polyurethane foams. Polymer Composites, 35(2), 301-309.
 Meng X.Y., Ye L., Zhang X.G., Tang J.H., Ji X., Li Z.M. (2009). Effects of expandable graphite and ammonium polyphosphate on the flame-retardant and mechanical properties of rigid polyurethane foams. Journal of Applied Polymer Science, 114(2), 853-863.
 Vanspeybroeck R., Van Hess P., Vandevelde P. (1992). Combustion behavior of polyurethane flexible foams under cone calorimetry test conditions. Cellular Polymers, 11(2), 96-117.
 Price D., Liu Y., Hull T.R., Milnes G.J., Kandola B.K., Horrocks A.R. (2002). Burning behaviour of foam/cotton fabric combinations in the cone calorimeter. Polymer Degradation and Stability, 77(2), 213-220.
 Kotresh T.M., Indushekar R., Subbulakshmi M.S., Vijayalakshmi S.N., Krishna Prasad A.S., Gaurav K. (2005). Evaluation of foam/single and multiple layer Nomex fabric combinations in the cone calorimeter. Polymer Testing, 24(5), 607-612.
 Lifeng Wu, Gemert J., Camargo R.E. (2012), Rheology Study in Polyurethane Rigid Foams. Huntsman International Technical presentations Web site: http://www. huntsman.com/polyurethanes/a/Products/Technical%20 presentations%20overview
 Prociak A. (Ed.), Rokicki G.. (Ed.), Ryszkowska J. (Ed.). (2014). Materialy poliuretanowe. Wydawnictwo Naukowe PWN SA (Warsaw).
 Levchik S.V., Weil E.D. (2004), Review Thermal decomposition, combustion and fire-retardancy of polyurethanes-a review of the recent literature. Polymer International, 53,1585-1610