Synergistic flame retardant effects and mechanisms of aluminum diethylphosphinate (AlPi) in combination with aluminum trihydrate (ATH) in UPR.

The synergistic flame retardant effects of AlPi and ATH in UPR were investigated. The flammability and thermal stability of UPR composites were evaluated with LOI, UL-94 vertical burning, MCC and TG. The structure and morphology of filler and char residues were examined with SEM and FTIR. The interaction between AlPi and ATH was observed when the mass ratio of AlPi and ATH was 3:2 and LOI value of flame-retarded UPR increased to 30 and UL-94 rating passed V-0; however, the SEM showed that AlPi and ATH have a good dispersion in UPR. The pHRR of UPR-15AlPi/10ATH was 241.6 Wg, decreasing by 30.4 % compared with pure UPR. The experimental TG curve of AlPi/ATH in N was lower than calculated one at the second stage and had lower char residue at 700 °C, demonstrating interaction of AlPi and ATH during thermal degradation. The char residue of UPR-15AlPi/10ATH at 700° suggested that the interaction between AlPi and ATH strengthened the char -formation ability and thermal stability of UPR, so the SEM showed a strong and dense char surface. The FTIR of char residues at different temperatures showed that AlPi and ATH interactions changed the type of aluminum phosphates, making char residue of UPR/AlPi/ATH system increased eventually. [ABSTRACT FROM AUTHOR]