Development of flame retardant polyphosphoric acid coating based on the polyelectrolyte multilayers technique

บทคัดย่อ

Polyelectrolyte multilayer (PEM) thin films were deposited on silk by sequential deposition of Chitosan and polyphosphoric acid. This PEM composition takes advantage of synergetic effect of the phosphorus and the nitrogen to provide an efficient coating, which prevents fiber decomposition at high temperature. Prior to the PEM assembly on silk fibers, the growth of the film was initially monitored using an atomic force microscopy (AFM). Films formed on silicon wafer after 10, 20, 30, 40 and 60 layers showed somewhat linear increase, which is consistent with the PEM technique. A total thickness ranging from 10 to 107 nm for the 10 to 60-layers films were found. Thermo-gravimetric analysis (TGA) was used to monitor the fiber decomposition as a function of increasing temperature. While the 10 layers coating was not show any improvement when compare with bare silk, the 30 and 60 layers coating showed significant difference in the thermograph. The decomposition of the fiber was significantly reduced which can be seen by the weight loss reduction even at 800 degrees. In conclusion the polyphosphoric based PEM coating seems a good candidate for the further development of flame retardant coating on silk fiber.