Preparation And Modification Of LDHs Flame Retardants And Its Application In Polypropylene

Several flame retardants ZnMgAl-LDHs, Sodium oleate modified ZnMgAl-LDHs, CuAl-LDHs, CuAl-LDHs-APP nanosheets were preparated by rapid nucleation/ crystallization, coprecipitation and one-pot in situ methods, respectively. And the effects of the above flame retardant on the flame retardant and mechanical properties of polypropylene (PP) have been investigated. The main results are obtained as follow:(1) ZnMgAl-LDHs were synthesized via a rapid nucleation/crystallization method and the surface of the ZnMgAl-LDHs was modified by sodium oleate. XRD, FTIR, TG and SEM/TEM were used to characterize ZnMgAl-LDHs and modified ZnMgAl-LDHs. ZnMgAl-LDHs/PP and modified ZnMgAl-LDHs/PP composites were prepared to invetigate their effects on the flame retardant and mechanical properties of the above PP composites. The results showed that:the sodium oleate modified ZnMgAl-LDHs has higher thermal stability, dispersibility and better compatibility between LDHs and PP; UL-94 vertical flame test and LOI tests showed that modified ZnMgAl-LDHs/PP had better vertical combustion properties and LOI value; compared to pure PP materials, the mechanical properties of LDHs/PP composites both decreased, but that of modified composite materials showed less declination. Adding the modified ZnMgAl-LDHs and synergistic effect flame retardant APP-PER to PP material. The as-obtained PP composite achieved good synergistic flame retardant effect when the ratio of modified ZnMgAl-LDHs to APP-PER was 7:3 (total addition amount of 30 wt%).(2) One-pot in situ approach was employed to synthesize CuAl-LDHs and then prepare CuAl-LDHs-APP and the effect of the mass ratio of NaAlO2/APP on the particle size of CuAl-LDHs-APP was investigated. The experimental results showed that the particle size of CuAl-LDHs-APP decreased gradually with the decreasing of the mass ratio of NaAlO2:APP. When the mass ratio of NaAlO2:APP was 0.82, the as-prepared CuAl-LDHs-APP had smallest particle size of about 20 nm, BET surface area of 183.5 m2/g, and better thermal stability at high temperature. The CuAl-LDHs and CuAl-LDHs-APP were added to PP to prepare LDHs/PP composites, investigating their fire-retardant and mechanical properties. The experimental results showed that CuAl-LDHs-APP4/PP composites had better vertical combustion performance and higher LOI value while decreased less in mechanical properties. The CuAl-LDHs-APP4 and DBDPE complex was used as synergistic flame retardant for PP materials, the experimental results showed that when the ratio of CuAl-LDHs-APP4 and DBDPE was 3:2 (both total addition amount of 30 wt%), the LOI value of the CuA1-LDHs-APP4/DBDPE/PP reached 26.8 while UL-94 vertical flame test met V-0 level.