The Investigation Of Flame Retardant Polypropylene Film

Polypropylene (PP) film with characteristics of light-mass, lower-poison, excellent electric insulation and mechanical property, has been widely applied in packing field. However, it has a low limiting oxygen index (LOI) value and is flammable. The fateful drawback of PP film restricts its wider application. This problem can be solved by using flame retardant additives, such as intumescent flame retardants which is low toxicity.In this work, a novel intumescent flame retardant (IFR) system consisting of novel char forming agent (CFA), modified ammonium polyphosphate (MAPP), synergistic agent 4A zeolite or composite of OMMT/Ethylene-Acrylic Este-Maleic Anhydride terpolymer (EAEM-OMMT) and antidripping agent SN3300 was used in intumescent flame retardant PP film (IFR-PP film).Alkane was grafted to the molecule of APP to enhance its compatibility with PP matrix. According to results obtained from the flame retardancy tests, MAPP had higher efficiency than original APP (OAPP) in IFR system, the IFR-PP film reached high limiting oxygen index (LOI) value but failed to pass UL-94 VTMO rating without antidripping agent until the load of IFR is 30wt%. The reasonable loading of SN3300 was 0.10-0.15wt%(IFR 26wt% loaded), more or less of it can't help the samples to pass VTMO rating and even deteriorated the flame-retardant performance.It is clear from the data of thermogravimetry analysis that the IFR enhanced the thermal stability of composites at high temperature and effectively increased the char residue. The cone results demonstrated that the IFR can effectively reduce the flammability behaviour of PP films based on reduced flammability parameters, such as heat release rate (HRR), total heat release (THR), smoke production rate (SPR), and total smoke production (TSP), and also IFR containing MAPP become more effective in reducing smoke release than that containing OAPP.The mechanical properties test results showed that films containing MAPP have better tensile strength and tear strength. The morphological characterizations observed by scanning electron microscope (SEM) showed that MAPP have much better compatibility in PP matrix than original OAPP and it made the char layer be more homogenous and dense.Composite of OMMT/Ethylene-Acrylic Este-Maleic Anhydride terpolymer (EAEM-OMMT) was used in intumescent flame retardant system. Then fire-retardant properties test, mechanical properties test and thermal gravimetric analysis were carried out and the results demonstrated that the EAEM-OMMT has good synergy. EAEM-OMMT not only improved the flame retardancy but also the mechanical properties of the system. When the load of IFR reached 28wt%, the IFR-PP film passed VTMO rate(0.23±1mm).