Ugis Cabulis

Two approaches for introduction of wheat straw lignin into rigid polyurethane foams

In present work the BIOLIGNIN TM obtained in the result of wheat straw organosolv processing in CIMV pilot plant (France) was investigated as a component of rigid polyurethanes (PUR) foam systems. Different separate approaches of lignin introduction into PUR foam system were studied: as filler without chemical preprocessing and as liquid lignopolyol obtained by lignin oxypropylation in alkali conditions. The incorporation of increasing amount of lignin as filler into reference PUR foam systems on the basis of mixture of commercial polyethers Lupranol 3300 and Luprano 3422 steadily decreased the compression characteristics of foams, their dimensional stability and hydrophobicity. The complete substitution of Lupranol 3300 by lignopolyol increases its cell structure uniformity and dimensional stability and does not reduce the physical-mechanical properties of foam. In both cases the incorporation of lignin into PUR foam leads to the decreasing of maximum values of thermodegradation rates. The lignin filler can be introduced into lignopolyol based PUR foam in higher quantity than in the reference Lupranol based PUR without reduction of compression characteristics of material. In this work the optimal lignin content in the end product - PUR foam as both polyol and filler is 16%.

Flammability of Bio-Based Rigid Polyurethane Foam as Sustainable Thermal Insulation Material

One of the biggest disadvantages of rigid polyurethane foams is its low thermal resistance, high flammability, and high smoke production when burning. Greatest advantage of this thermal insulation material is its low thermal conductivity, which at 20–25 mW/(m·K) is superior to other commercially available insulation materials. In recent years polyurethane materials from renewable resources have been widely studied. But their use on industrial scale was limited due to inconstant performance and relatively high price of raw materials. Different bio-based raw materials, such as rapeseed oil and tall oil, could provide abundant feedstock for PU foam production. Decrease of flammability of PU materials conventionally is achieved by addition of flame retardants, halogen-containing compounds, and phosphates. It can be consid‐ ered that halogenated fire retardants could have several health hazards, such as volatile compound emission from materials and toxic gas release during burning process. Expandable graphite could be an answer to this flammability problem. This chapter describes development of bio-based rigid polyurethane foams and their flammability reduction using sustainable flame retardants. Different expandable graphite intumes‐ cent flame retardants provided significant flammability reduction while maintaining low thermal conductivity of insulation materials.