| As halogen-free and environmentally friendly flame retardants, intumescent flame retardants (IFR) have been widely used in polymer materials, different components of the flame retardants for different polymers produce different effects. However, IFR has its drawbacks, such as the high loading and the incompatibility with the polymer. In order to solve these problems, taking epoxy resin (EP) and polypropylene (PP) as matrix, we have done the works as following:1. KDIFR, which was synthesized from pentaerythritol (PER), phosphorus pentoxide (P2O5), and melamine (M) is a good IFR, but it was acidity (pH≈3~4), high loading. In order to improve the performance of KDIFR, Mg(OH)2·4MgCO3·6H2O or/and CaCO3, acted as synergetic agents and neutralizing agents, could be chosen to modify in situ KDIFR. PP/KDIFR/MgO/CaO composites were preapared by means of melt blending. The fire retardant efficiency of MgO or/and CaO as synergistic agents in polypropylene (PP) was investigated using horizontal combustion test, the limiting oxygen index (LOI), cone calorimeter test (CONE) and thermal analysis (TG-DTA). The results showed that MgO and CaO exhibited a synergistic effect on fire retardancy. Only <0.2% of MgO or/and CaO in PP/KDIFR composite could decrease the self-extinguishing time and enhance the LOI value obviously. The CONE and the thermal analysis results revealed that the introduction of MgO and CaO neutralized the acidity of KDIFR, which led to a delay of the intumescent process of the system and a thermal stabilization, and promoted to form a high quality charred layer which can prevent PP from decomposing. Thus, a suitable amount of MgO or/and CaO played a synergistic effect in the flame retardancy in PP/KDIFR system. However, excess MgO or/and CaO led to the lack of acid catalysis, and the flame-retardant effect decreased.2. MAPP, which was prepared by melamine formaldehyde resin (MF) microencapsulated ammonium polyphosphate (APP) is an excellent IFR. However, it has high surface energy because of its polarity, while PP has low surface energy, so it is poor for the compatibility between PP and MAPP. The effect of alkyl silicone oil (ASO) as a compatibilizer on the compatibility of Polypropylene/Microencapsulated Ammonium Polyphosphate (PP/MAPP) composites was investigated. The data from the mechanical tests showed when 0.25% ASO was added, the tensile strength of PP/MAPP/ASO composite increased approximately 41% compared with that of PP/MAPP composite, the best comprehensive performance was shown. POM and X-ray diffraction (XRD) demonstrated that ASO decreased the reunion phenomenon of MAPP, and made MAPP dispersed homogeneously in PP. SEM results illustrated that ASO improved the interfacial adhesion between MAPP and PP. IR and rheological studies indicated that ASO played the role of lubricant in PP/MAPP, and flow behavior of composites in the melt was that of a pseudoplastic liquid and MAPP interacted with ASO by molecule interaction. All the investigations showed that a suitable amount of ASO improved the compatibility of the PP/MAPP composite.3. Three intumescent flame retardant, KDIFR, MAPP and APP as well as boron and aluminum were introduced separately into epoxy resin (EP) and their effects were compared. Limiting oxygen index (LOI) and horizontal burning test showed that APP had the best flame retardancy behavior among the three, when the mass ratio of APP/EP was 0.3, the LOI value reached 32.2%. The flame retardancy property of EP/APP could be further improved by introducing either aluminum or boron, or better of the both. When the content of aluminum borate was 0.8 wt%, the self-extinguishing time of EP/APP decreased to 24s from 48s. Thermal analysis indicated that heat absorbed during thermal decomposition of APP nearly matched that released during the thermal degradation of EP, which was the main reason of APP's good behavior. The charred yield of EP/APP was promoted obviously when introducing aluminum and boron in EP/APP composite.
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