Hot hardeners

For efficient curing of urea-formaldehyde (UF) resins at low temperatures, strong acids are needed as cold hardeners. A drawback of such use of strong acids is that the acid attacks wood. Water-soluble organic acids like citric or tartaric acids reduce the danger of attack on wood. Hot hardeners are ammonium salts of strong acids like ammonium chloride or ammonium sulfate that liberate the acid at high temperatures. 

Water based dl solvent based dl chemical reaction dl cold dl hot hardening One component dl two components dl Hot melt dl other... 

The vulcanised carborane-siloxane rubber [530] has an unusual degree of thermal stability it does not show any persistent changes after 100 h at 250 °C in the open air. Hot-hardened rubbers are used mainly in electrical engineering and the aircraft industry. Those intended for medical applications may be vulcanised under radiation without a catalyst. 

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