a It seems that several papers on starch-SPB, starch + SPB (soufa 23% aqueous solution), have been published.
Sofa can be used in combination with starch to form an excellent flame retardant coating as a carbonization aid.
Mixture of starch and amorphous sodium polyborate (SPB) is found to show high flame retardancy, when its aqueous solution is deposited and dried on organic polymer materials such as polyethylene terephthalate (PET) nonwoven, rigid polyurethane (RPU) foam, and polypropylene (PP) nonwoven. The PET nonwoven (10mm thickness) and the RPU foam (10mm thickness) coated with the mixture endure the premixed flame of butane gas burner with length of 100mm for more than 12min. The PP nonwoven (0.7mm thickness) endures the nonpremixed flame with length of 65mm in the 45 degrees Meckel burner test for more than 2min. The backside temperatures in the both tests remain below 130°C. The thermal analyses and the SEM observation indicate the mechanism that the SPB foam promotes the carbonization of starch and that the carbonized layer together with the SPB foam insulate inside from oxygen and heat.
The following shows the flame retardancy of starch a starch-SPB.
Combustion of cardboard