Study On The Flame Retardant And Smoke Suppression Effect Of The APP-FeCl₃-Molecular Sieve5A On Wood

As a renewable material, wood not only has the natural texture and beauty, but also has many advantages of other materials cannot match, so it has an important position in the building decoration materials. But wood is flammable, the initiation and spread of many fire has related with its, so flame and smoke suppression treatment for wood is very necessary. Ammonium polyphosphate (APP) is a commonly used wood flame retardant, and has the advantages of high flame retardant efficiency and cheap price. However, APP also produces a lot of smoke and toxic gas when carry out the flame retardant effect. Molecular sieve has the advantages of uniform pore structure and large specific surface area, often used as adsorbent and catalyst. In additional, the transition metal is often used as catalyst for some oxidation reaction. In view of these characteristics of molecular sieve and transition metal, the transition metal was supported in the pores of molecular sieve and compose composite flame retardant with APP in this study. And this composite flame retardant was effect on wood, so as to study the characteristics and mechanism of flame, smoke suppression and attenuation.The effect of flame retardance, smoke suppression and smoke control of ammonium polyphosphate on wood was studied by cone calorimeter method. The results showed that total heat release and total smoke production of wood reduced by47.64%and61.40%respectively with the effect of ammonium polyphosphate, indicating efficient flame retardant and smoke suppression. But the cracking gas burned incompletely due to the gas flame retardant mechanism of ammonium polyphosphate has the characteristic of isolated from oxygen, resulting in more CO and other poisonous gases. Therefore the ammonium polyphosphate can’t be used as a wood fire retardant alone, it should be used with other materials which has the effect of weakening toxicity.It was confirmed that the addition of molecular sieve could promote smoke suppression of APP to wood and the CO production was reduced greatly. Compared the characteristics of flame retardant, smoke suppression and toxicity weakening of five kinds of molecular sieves and APP flame retardant composite, selecting the five kinds of molecular sieves which has the best effect of flame retardant, smoke suppression and toxicity weakening. The characteristics of flame retardant, smoke suppression and toxicity weakening of the composite of6kinds of metal salt which was loaded in molecular sieve and APP was compared and the molecular sieve loaded with FeCl3has the best effect of flame retardant, smoke suppression and toxicity weakening. When optimizing the modified proportion of Fe element and5A molecular sieve, it is concluded that the best effect of flame retardant, smoke suppression and toxicity weakening could be achieved when mass ratio of the Fe element and5A molecular sieve was15%.Two kinds of5A molecular sievemodified with FeCl3whcih was generated by loading method and mixing method, respectively, were made. The flame retardancy, smoke suppression and attenuation effect of wood treated with the two different kinds of5A molecular sieve was compared. The results showed that, the flame retardancy and smoke suppression effect of composite flame retardant by loading method was slightly better than that of flame retardant by mixing method, while CO yield of composite flame retardant by loading method was much less than that of flame retardant by mixing method. Comprehensive consideration, loading method used to make composite flame retardant was selected.The methods of thermogravimetry analysis (TGA), scanning electron microscope (SEM) and py-GC-MS were used to reveal the mechanism of flame retardancy and smoke suppression regulation effect of wood treated with APP, molecular sieve and molecular sieve modificated with FeCl3. APP could change the cleavage direction of wood that generated more carbon and water. The stable dense carbon layer difficult to produce small particles was also generated, so as to achieve the effect of protecting the internal wood and reducing the release of smoke. The use of molecular sieves and the element of Fe can catalyze and oxidise CO and make the react of polycyclic aromatic compound deeply, to produce more small molecules such as CO2.Therefore, the purpose of reducing toxic gases with the use of APP used as flame retardant for wood was achieved.