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Synthesis of polypropylene/organo-layered double hydroxide (PP/OLDH) has been carried out based on self-assembled organocobalt-aluminum LDH (O-CoAl-LDH). The novel method of synthesizing self-assembled CoAl-LDH and its characterization have also been reported in details. This method is proven to be very efficient way of producing OLDH in a single step with homogeneous composition and structure. As flame-retardant nanofiller, O-CoAl-LDH shows significant decrease in heat release rate (HRR), the total heat release (THR) and the heat release capacity (HRC) of the PP composites, though the thermal stability of the compounds decreases slightly compared to the base polymer. Morphological analyses show that the LDH particles are dispersed in PP matrix in a partially exfoliated form. The activation energy calculation based on the Kissinger method reveals that O-CoAl-LDH has a positive effect on the activation energy of thermal decomposition of PP. However, in the presence of this filler, decomposition of the composites starts at an earlier stage than that of pure PP.

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A novel one-step method has been developed to synthesize organically modified layered double hydroxide under ambient condition and without requirement of carbonate-free condition. This method has been found to be effective in the presence of several competitive anions and provides modified products with improved homogeneity, crystallinity, etc., as compared to other commonly known methods such as anion exchange and regeneration. The critical control of the pH value of the reaction medium is a key aspect of this method and provides a high degree of intercalation of the surfactant without forming any pure LDH phase. WAXS and FTIR analysis prove the homogeneous nature of the modified LDH. In contrast to the regeneration method, the chemical environment of the metal hydroxide layers remains identical to that of the unmodified LDH, as confirmed from the solid-state 27Al MAS NMR spectroscopy.

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