Intumescence is the result of a combination of charring and foaming at the surface of the burning polymer, which protects the underlying material from the action of the heat or flame. Intumescent FRs (IFRs) is often used for applications requiring high levels of flame retardancy. They are highly efficient and low toxic. They provide very robust fire safety and flame resistance performance. The carbon agent forms multicellular charred layers, the char may be soft or hard [5]. Soft char IFRs: composed of a carbon source pentaerythritol (PER), acid source (Ammonium Polyphosphate) and a gas-blowing additive (melamine) harder char IFRs: composed of sodium silicates and graphite. These are suitable for use in plastic pipe firestops as well as exterior steel fireproofing.
PER is quite costly. A possible substitute is green carbon agent is chitosan (CS), obtained by the alkaline deacetylation of abundantly naturally occurring chitin. A good synergistic effect observed when chitosan/urea compound based phosphonic acid melamine salt (HUMCS), was added to an IFR system for polypropylene (PP) [5]. A reactive, intumescent, HFFRs 2-({9-[(4,6-diamino-1,3,5-triazin-2- yl)amino]-3,9-dioxido-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5] undecan-3-yl}oxy) ethyl methacrylate (EADP), synthesized from phosphorus oxychloride, pentaerythritol, hydroxyethyl methacrylate, and melamine. EADP (Figure 2) exhibited excellent thermal stability and char-forming ability without affecting tensile strength of polypropylene [6].
Novista Group supplies APP, MCA, aluminium hydroxide,magnesium hydroxide to global market.
