Binary Modification Of Ammonium Polyphosphate (Si@MAPP) And Its Influence On Polypropylene Composites

Polypropylene (PP) occupies large part in the polymer consumption owing to its advantage such as superior mechanical properties, easy to process, low price, etc. However, PP is lack in flammability, smoke and poisonous gas is emitted while it is burning. These defects limit the range of application of PP. So, recently many researchers focus on the flame retardancy of PP to expand the scope of its application fields. And intumescent flame retardant (IFR) has drawn more and more attentions due to its friendly environmental characters like low smoke and non-toxic gases.The modification of ammonium polyphosphate (APP) with silane coupling agents and melamine formaldehyde resin were studied to improve the water resistance and mechanical properties of PP/IFR composites in this paper.Firstly, Three silane coupling agents, (3-aminopropyl)-triethoxysilane (KH550), 3-methacryloxypropyltrimethoxysilane (KH570) and vinyl triethoxysilane (A-151), were used modificating APP to prepare SiAPP. It was proved that 3wt.% of KH550 was the optimized dosage which made the lowest water solubility of SiAPP and gave PP/IFR composites the optimized properties. The solubility of SiAPP was decreased 45% compared to APP, PP/IFR successfully passed the vertically combustion UL-94 V-0 level test and the LOI value reached 36.3%. Meanwhile, its tensile and flexural strength raised 12% and 21% respectively, and water resistance enhanced a lot compared to PP/IFR composites after modification. Secondly, Microencapsulation ammonium (MAPP) used as flame retardant in PP was prepared using melamine formaldehyde resin (MF). The hydrophobic property improved compared to SiAPP. With 30% addition of IFR, PP composites passed the vertically combustion UL-94 V-0 level test with the LOI value of 36.5%. And the mechanical properties of PP/IFR composites increased 18% and water resistance improved obviously as well. At last, KH550 modificated MAPP was investigated to prepare Si@MAPP. Results showed that LOI value reached 37.8% and the mechanical properties of PP/IFR composites increased 32%, which means the new method made futhter improvement on the properties of PP/IFR composites.