Study On Halogen Free Flame Retardant Polyolefin

Polyolefin is widely used in many industries such as electronics, electrical devices and automobiles. However, because of its flammability, polyolefin is one potential fire risk. Moreover, there has been increased concern over the use of halogen-type flame retardant. Therefore, it is worthwhile to develop halogen-free flame retardant polyolefin.Two ways are developed to achieve HFFR polyolefin.On the one hand, given the fact that there is a rich and cheap resource of brucite in China, brucite is used as the primary flame retardant. The effects of brucite and its synergic agents, such as microcapsulated red phosphorus and zinc borate, on flame retardancy, thermal stability, and mechanical properties of LDPE/EVA blends were investigated. Through orthogonal design, in which the ratio of LDPE to EVA, the loading of brucite and its synergic agents are factors, an optimum FR formulation was obtained, which provides a good balance between flame retardancy and mechanical properties. To improve these properties further, several surface modifiers, such as ADDP and stearic acid, were used to treat the brucite. The effects of different modifiers and their dosage on the properties of the brucite were examined by several analytic methods, including water adsorption,oil adsorption and contact angle. The mechanism of absorption was studied by analyzing FTIR and the change of the contact angle of surface modified brucite after solvent extraction. The dispersion of treated and untreated brucite in the composites was assessed by SEM. The results showed that the surface properties of treated brucite changed from hydrophilic to hydrophobic,the adsorption behavior of surface modifiers included chemical adsorption and physical adsorption, and dispersion of brucite in LDPE/EVA and compatibilization between brucite and polymer-matrix improved. Finally, treated brucite was applied in PO flame retardant formulations. The flame retardancy and mechanical properties of FR composites were improved remarkably, achieving the Chinese standard of halogen free flame retardant cable covering. The results also suggested that different adsorption behavior of surface modifiers influence the properties of FR composites.On the other hand, the intumescent flame retardant named pentaerythritol bisphosphorate melamine salt was synthesized from H3PO4, P2O5, pentaerythritol and melamine. The optimum synthetic condition was obtained according to intumescent degree, char residual and water absorption. Moreover, the IFR was applied in polyethylene. The flame retardancy and mechanical properties of IFR/LDPE composites were investigated by the limiting oxygen index, horizontal burning test and mechanical measurements. The test results showed that intumescent degree, char residual could reflect the flame retardancy of IFR in LDPE. The IFR formulation of 3∶1∶1 mixed with LDPE in 30∶70 made the composites achieve a LOI value of 29, FH-1 and the...