Aromatic polyols flame retardancy

The advantages of these aromatic polyesters are lower cost than conventional polyether polyols, better flame retardance, and high-temperature resistence. However, their disadvantages include compatibility problems with chlorofluorocarbons and quality deviations in viscosity and hydroxyl values. In order to improve the compatibility problems, amine-based polyether polyols have been blended. 

Aromatic polyols and triazinic polyols lead to polyurethanes with superior fire resistance due to the high char yield generated during the burning process. Sometimes, the rigid polyurethanes based on aromatic and triazinic polyols have an intrinsic flame retardancy (gives self-extinguishing foams without the addition of flame retardants). 

Flame retardant flexible foams are very difficult to obtain due to the low crosslink density, low aromaticity, open cell structure and long polyolic aliphatic chains. Generally, flame retardants flexible foams are produced with additive flame retardants, for example with powdered melamine + tris (2-chloropropyl) phosphate [14]. 

Flame retardant rigid PU foams, due to their high aromaticity, and high crosslink density are easier to be obtain. An aromatic polyol has a supplementary contribution to improving the fire resistance (for example Mannich polyols, novolak polyols, triazinic polyols based... 

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