Fabrication of Halogen-free Ammonium Phosphate with Two Components via a Simple Method Way and its Flame-retardancy in Polypropylene Composites Zaihang Zhenga,b,*, Yan Liub,*, Long Zhanga, Boya Daia, Xudong Yanga, Hongyan

Wangc a. School of Chemical Engineering, Changchun University of Technology, Changchun

130012, P.R. China b. Key Laboratory of Bionic Engineering (Ministry of Education), Jilin University,

Changchun 130022, P.R. China c. College of Chemistry, Jilin University, Changchun 130012, P.R. China

*Corresponding author.

Dr. Zaihang Zheng

College of Chemical Engineering, Changchun University of Technology, Changchun

130012, P.R. China

Email address: [email protected]

Tel.: + 86-431-85168470; fax: +86-431-85175863 Supplementary Material

Fig. S1 Thermal oxidation behavior of PP composites, (a) TG curves, (b) DTG curves Fig. S2 The analysis on thermal pyrolysis process of APP In order to compare MAPP, the study on the thermal oxidative process analysis of

APP was also investigated. The char residue obtained at different thermal pyrolysis temperature was characterized by FTIR spectra. APP was heated in 10 °C min-1 heating rate in thermal gravimetric analyzer in air atmosphere. The residues were obtained by heating the mixture powder to 300, 350, 400, 450, 500, and 600 °C in air and maintained 10 min at every temperature, respectively. The detailed FTIR curves of these residues are shown in Fig. S2. Obviously, the relative intensity at 3100-3300 cm-1 gradually fades with the increment of temperature and disappears at 600 °C.

During this process, the thermal degradation of -NH4 groups on APP produces NH3 gas and generates -OH groups on side chains of P-O-P. This fact is also confirmed by

TGA curves in Fig. 3. Besides, the peaks of P=O and P-O-P shift from 1256 and 880 cm-1 to 1233 and 920 cm-1 with the temperature increasing. This is mainly ascribed to the main chains decomposition of APP. In this process, APP gradually converts to

crosslinked polyphosphoric acids (PPA) and P2O5 or P4O10. Except that, the peaks at 992 and 887 cm-1 (P-O bonds on the P-O-C groups) for the thermal oxidative degradation of MAPP do not appear in FTIR spectra of APP. These facts demonstrate that thermal oxidative process of APP and MAPP experiences the two different mechanisms. On one hand, the cross-linking reaction of MAPP occurs between APP and diethanolamine to generate the char residue; on the other hand, the thermal degradation of APP only happens on itself and can not produce the cross-linking reaction. This further certifies the reason for the improvement in flame retardancy of

PP/APP after the introduction of diethanolamine onto APP. Table S1 The data for the thermal oxidation decomposition of PP composites

a b c Sample Ton Tmax Char residue/wt% Rmax /°C /°C 500 °C 600 °C 700 °C % °C-1 PP 313.8 440.5 0 0 0 -0.923 PP/APP 350.9 443.8 13.94 8.71 4.19 -0.924 PP/MAPP 322.6 452.5 15.37 8.46 6.08 -1.324 a Ton: the temperature at 5 % mass loss b Tmax: the temperature at maximum mass loss rate c Rmax: maximum decomposition rate