Structure Control And Properties Of Inorganic Fire-retardents With Effective Smoke Inhibition Properties

The key difficulty which must be overcome in the synthesis of inorganic-organicnanocomposetes is the incompatilitity between the surfaces of the inorganic and organiccomponents. In this ,There are propore that the lcontrolling the crystallization ofLayered Double Hydroxide (LDHs), small-sized LDHs crystals can be synthesized andevenly dispersed in PE to give fire retardant properties. Because of the layered structure of LDH, the presence of exchangealbe interlayeranions and the ability to control the composition of the layers,we propose that a newtype of fire-retardant with high high-inhibiting properties can be made by intercalatingphosphate anions into the interlayer of LDH to combine the properties of smokeinhibition and fire-retardancy. This thesis desirbes research on the synthesis, structureand properties of small-sized LDH and phosphate-pillared LDH. Mg-Al LDHs have been synthesized from Mg(NO3)2·6H2O,Al(NO3)2·9H2O,NaOH and Na2CO3 in a colloid. It was found that the aging temperature, degree ofsupersaturation in the course of aging and degree of supersaturation in the course ofnucleation are the important factors affecting the crystal structure and crystallite sizes ofKDHs. Lower aging temperatures and addition of water during the aging process favorthe formation of nano-sized hydrotalcites. When the concentration of Mg2+ is in therange 0.1~1.6mol/L the particle size of LDH increases with increase of the Mg2+concentration. Secondly, by controlling the pH value, different phosphate-pillared hydrotalciteshave been synthesized using carbonate hydrotalcites as precursor. under acidic iii北京化工大学硕士学位论文conditions (pH=4.5), LDH-Mg-Al-H2PO4 has been synthesized; also, by controlling themolar proportion of the precursor and the intercalated anions, LDHs containing bothCO3 and H2PO4 can be prepared. Under basic conditions,LDH-Mg-Al-HPO4 can be 2- 2-synthesized using a reprecipitation method。With the increase of pH value, the layerstructure of pillared LDHs begins to appear and crystallinity increases. When the pHvalue reaches 11.5,the crystallinity of LDH-HPO4 is relatively high. The supramolecular structure of phosphate-pillared Mg-Al-LDH has been studiedby XRD, FT-IR, TG-DTA and it is suggested that phosphate-pillared LDH is not asimple combination of phosphate anions and LDH. The supramolecular host-guestinteractions involve electrostatic forces and hydrogen bonds whilst there is covalentbonding within the fost layes and intermolecular interactions between the guest anionsin the interlayer region. The regular arrangement of phosphate guest ions in theinterlayer region results in the infrared absorbing properties and thermal stability of thephosphate-pillared LDH being very different from the LDH carbonate precursor. Inorganic fire-retardant/PE composite materials have been produced in order tostudy the properties of smoke inhibition and fire-retardance by (LOI) and (DM)。Theresults show that at low additive quantity (70phr), nano-sized LDH, nano-sized Mg(OH)2 and supramolecular phosphate-pillared LDH all have good fire-retardantproperties. Nano-sized LDH shows a nano-size effect so that the property of smokeinhibition and fire-retardance both improve significantly; supermolecularphosphate-pillared LDH shows a cooperative effect of nano-sized LDH and inorganicphosphate fire-retardants which enhance the smoke inhibition property whilst the highfire-retardance of nano-sized LDHs remaining unaffected.