Preparation And Performances Of Polypropylene/LDHs Composites

Layered Double Hydroxides (LDHs) have been modified by sodium dodecylsulfonate (SDS) using ion exchange method and the changes of thermal stability and d-spacing were studied. Polypropylene/LDHs composites were prepared by using melting mixing method. The mechanical properties, fire retardance, isothermal crystallization were investigated.For the fire retardance study, ammonium polyphosphate (APP) and melamine (MEL) were used as fire retardants. And maleic anhydride grafted polypropylene (PP-g-MAH) was selected as a compatilizer. In addition, the micro-structure, crystallization and mechancal properties of relevant composites were also studied. As a result, the optimized formula of PP/LDHs was concluded.The result shows that modifiers can enter into the layers of LDHs and layer spaces of LDHs are enhanced. Layer space of modified LDHs with contain sodium dodecylsulfonate is bigger than that of unmodified LDHs. The experiment results show that the limiting oxygen index (LOI) of PP/20%LDH-SDS is 24% which is higher than that of PP/LDHs, and LDH-SDS has better dispersion stability than that of unmodified LDHs.The research resaults of PP/LDHs/APP,PP/PP-g-MAH/LDHs/APP,PP/LDHs/APP/MEL nanocomposites show that: when the addition of APP reaches 30%, the LOI of PP/LDHs/APP increases to 24%.In comparison to other nanocomposites, PP/3%LDHs/APP/MEL comparatively high tensile strength and limiting oxygen index (LOI) is 23%.The initial interlayer of LDHs can be replaced with H₂PO₄^- by ion-exchange method.The results indicated that LDH-APP was LDH-H2PO4 compound APP and the flame retardant synergism of PP/LDH-APP results show that the limiting oxygen index (LOI) of PP/LDH-APP by 20% of LDH-APP is 24%.