Study Of Preparation And Synergestic Effect Of Molecular Sieve And Phosphorus And Nitrogen Flame Retardants In Plywood

Fire disaster possesses great threat to people’s life and property and wood as a kind of flammable materials further brings potential damage to the living environment. Researching and developing of new flame retardant of wood materials which can lower the burning rate, flame propagation speed and furthermore, can reduce the large amount of harmful gases produced during combustion is of great importance.In this paper, we prepared nitrogen and phosphorus flame retardants using urea and phosphoric acid as main raw materials and then modified with 4A molecular sieve. Finally, we used modified flame retardants to treat poplar veneer and prepare plywood. Effects of modified flame retardants on moisture absorption, oxygen index, flammability, chemical elements analysis and so on of treated poplar veneer were characterized by oxygen Index (LOI), cone calorimeter (Cone), scanning electron microscopy (SEM) and energy spectrum analysis (EDS). And mechanical, bonding and thermal properties were characterized by universal mechanical testing and TGA-FTIR analysis (TG-FTIR). Besides, we preliminarily studied the mechanism of flame retardant. The results were as follows:(1) Drug loading and moisture absorption rate of poplar veneer treatred by APP flame retardant increased with the increasing concentration of APP. The drug loading of specimens were 34.44 and 43.06 kg/m3 when the APP concentration were 15% and 20%. The addition of 4A or 13X molecular sieve to APP could increase drug loading and reduce moisture absorption rate of poplar veneer. The oxygen index of poplar veneer tended to increase with the increaseing of APP concentration, but it slightly reduced after the addition of molecular sieve.(2) The molecular sieve/APP composite flame retardants was used to treat poplar veneer and prepare plywood. Results showed that the addition of APP flame retardant could significantly reduce heat release during combustion, but increase the release of smoke. The smoke emission and total CO emission of plywood specimens treated by APP flame retardant were 2.6 and 1.2 times than those of untreated plywood.(3) Molecular sieve was added to the retardants and the ratio of raw materials was optimized. Then flame-retardant plywood modified by different flame retardants was prepared. Results showed that the optimum addition of molecular sieve was 2% and molar ratio of phosphoric acid and urea was 1:2. And the plywood midified by this flame retardant exhibited excellent smoke suppression performance and thermal stability. Though the bonding strength was lowered, it could still meet the requirements specified of GB/T9846-2004 about class Ⅱ plywood(≥0.7MPa).