| Polypropylene(PP) is one kind of hydrocarbons materials and it's extremely inflammable which limits its extensive application. At present, the main method of inflaming retarding is adding flame retardants in PP. In view of the requirements of environment protection, halogen-free inflaming retarding PP becomes the current research hotspot. But the amount of halogen-free flame retardant is usually relatively large which has a great influence on mechanical properties and processing properties of materials. Therefore, developing halogen-free inflaming retarding PP with advantages of high efficiency, environment protection and excellent mechanical properties becomes essential.Firstly, in this topic the research development and inflaming retarding mechanism of polyethylene into which halogen-free flame retardants were added were discussed. According to this, the inflaming retarding system in which aluminum hydroxide and magnesium hydroxide were blended with flame retardant and zinc borate was added as assisting element was chosen. Then in consideration of destruction of mechanical properties and processing properties of PP caused by flame retardants, the rigid inorganic particles CaCO3 and POE through superficial treatment were chosen to fill inflaming retarding polypropylene. The PP/Al(OH)3/Mg(OH)2/ZB,PP/Al(OH)3/ Mg(OH)2/ZB/CaCO3 and PP/Al(OH)3/Mg(OH)2/ZB/CaCO3/POE composites materials were prepared using the method of molten blending. On the basis of contrastive analysis of the three systems, the inflaming retarding, mechanical and flow properties of each system were studied, and the mechanism was preliminarily discussed.The inflaming retarding properties mainly include oxygen index, smoke density and level combustion rate. Results showed that with the increase of flame retardant additives, the oxygen index of systems gradually increased while level combustion rate and smoke density substantially declined. In the condition of adding the same amount of flame retardant additives to the systems, the oxygen indexes of the system added CaCO3 and the system added CaCO3 and POE increased while the smoke density declined, which would be favorable for inflaming retarding meanwhile would slightly increase the level combustion rate.Mechanical properties mainly include tensile property and impact property. Results showed that with the increase of flame retardant additives, the breaking strain, tensile strength and elongation at break declined, but the elasticity modulus increased. The impact strength of V type gap sample firstly increased and then decreased. In the condition of adding the same amount of flame retardant additives to the systems, the breaking stain, elongation at break and impact strength of the system added CaCO3 and the system added CaCO3 and POE increased, the mechanical properties of systems improved. The impact strength of the system added CaCO3 and POE improved obviously.Flow performance test is mainly the determination of the melt volume flow rate. Results showed that with the increase of flame retardant additives, the melt volume flow rate nearly linearly declined, and the larger the load, the larger the melt volume flow rate became. The calcium carbonate that through superficial treatment could be compatible with matrix better, which would make the melt volume flow rate larger.The research results in this study are expected to provide theoretical basis and guidance to design and application of halogen-free inflaming retarding PP.
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