Synthesis of zinc N-morpholinomethylphosphonic acid and its application in high density polyethylene

• A novel flame retardant zinc N-morpholinomethylphosphonic acid (MMPA-Zn) with layered structure is synthesized and characterized.
• The data indicate the good thermal stability and char-forming ability of MMPA-Zn.
• MMPA-Zn is effective to promote the carbonization process of HDPE/MMPA-Zn composites.
• The emission of CO reduced obviously with the increase of MMPA-Zn, which means MMPA-Zn could be deemed as an effective toxic-gas suppressant in high density polyethylene.

Zinc N-morpholinomethylphosphonic acid (MMPA-Zn) is synthesized by hydrothermal reactions used zinc acetate and N-morpholinomethylphosphonic acid as raw materials. TGA shows that the TG onset temperature of decomposition of MMPA-Zn is 391 °C and the final residue at 700 °C is 65.3 wt%, indicating its good thermal stability and char-forming ability. Then, MMPA-Zn is used as flame retardant in high density polyethylene (HDPE). The thermal property and flame retardancy of various HDPE compositions were investigated by TGA and cone calorimeter (Cone). TG data show that MMPA-Zn can improve the thermal stability and char residue yield, which is dependent on the loading amount of MMPA-Zn. The Cone data indicate that the PHRR and the emission of CO decreased obviously because of the joint effect of Zn and the MMPA in MMPA-Zn molecular, which can yield more char residue in the HDPE/MMPA-Zn system.