Study On The Synthesis And Flame Retardant Property Of Hydrophobic Ultrafine Aluminum Hydroxide

Aluminum hydroxide belongs to inorganic flame retardant, its advantagesinclude flame retardant, smoke suppression and filling, it is one of the most widely-used halogen-free flame retardant. It is chemically inert, non-toxic, and does notproduce secondary pollution; it is rich source of low price, so its consumptionaccounted for more than50%of the total amount of flame retardants in foreignmarkets. Therefore, aluminum hydroxide is a kind of promising green and safe flameretardant. However, aluminum hydroxide also has significant drawbacks, it has poorcompatibility with polymer material, this could be negative for the flame retardancy.What’s more, the particle size has great impact on flame retardant property andmechanical property of materials. The bigger particle size of aluminum hydroxide is,the worse properties of the materials get. So people usually use two ways to improvethese deficiencies, surface modification and ultrafine.In general, people preparedaluminum hydroxide in advance, and then subjected it to surface-modified. Butultrafine aluminum hydroxide or nano-aluminum hydroxide is easy to agglomerate,this makes it difficult to reprocess. So people are trying to find a easier and moreefficient way.In this article, hydrophobic ultrafine aluminum hydroxide Al(OH)3(called M-Al(OH)3) nanoparticles are prepared by one step in situ surface modification method,then added them to the polyethylene resin by melt-blending method, at last, wecharacterize the flame retardant property and mechanical property of compositematerials. The main tasks are as follows:1. We use one step in situ surface modification method to synthesizehydrophobic ultrafine Al(OH)3powder, the minimum average particle size can be89.4nm and the contact angle is as high as116°which turns out to be quite hydrophobic. All these are controlled by the synthesis conditions, including synthesistemperature, pH, the rotational speed, the amount of modifying agent and, theconcentration of the solution.2. The IR of M-Al(OH)3shows that the oleic acid molecules do not adsorbAl(OH)3in [Al(OH)3]n(OH)x-y(OOCC17H33)ysuch form instead of C17H33COO-Al(OH)3such way.3. The TG curves show that compared to the hydrophilic Al(OH)3, the M-Al(OH)3has wider thermal decomposition temperature. This makes it possible thatthe M-Al(OH)3can be applied to polymer materials which have higher processingtemperature.4. The hydrophobic and hydrophilic Al(OH)3powder are added to polyethyleneresin by melt-blending method, and then we characterize the flame retardant propertyand mechanical property of composite materials. The results show that the compositematerial contained M-Al(OH)3is superior to the composite material contained byhydrophilic Al(OH)3. The flame retardant properties of the composite material can beincreased by35%when added in an amount of50%. But with the increase of amountof M-Al(OH)3, the mechanical property of the composite material decreases.