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Effects of flame retardants integrated with citrate and ammonium polyphosphate on thermal stability and flame retardancy of thermoplastic polyurethane elastomer
Author(s) -
Chen Xilei,
Wang Ke,
Li Shaoxiang,
Jiao Chuanmei
Publication year - 2021
Publication title -
polymers for advanced technologies
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.61
H-Index - 90
eISSN - 1099-1581
pISSN - 1042-7147
DOI - 10.1002/pat.5296
Subject(s) - thermoplastic polyurethane , ammonium polyphosphate , materials science , fire retardant , limiting oxygen index , cone calorimeter , thermal stability , composite material , nuclear chemistry , char , thermogravimetric analysis , chemical engineering , elastomer , pyrolysis , chemistry , engineering
Three citrates, which incorporate cobalt citrate (CoC), copper citrate (CuC), and yttrium citrate (YC), were combined with ammonium polyphosphate (APP) as a flame retardant to improve the flame retardancy and thermal stability of thermoplastic polyurethane (TPU). The cone calorimeter test (CCT) results demonstrated that the PHRR (peak heat release rate) values of TPU‐2, TPU‐3, and TPU‐4 were decreased from 271.4 kW/m 2 for TPU‐1 to 188.0, 256.9, and 219.0 kW/m 2 , respectively. Besides, compared with TPU‐1, the release of CO and CO 2 of TPU composites that containing citrate were decreased. The limiting oxygen index (LOI) value for TPU‐1 (containing 8.0 wt% APP) was 26.5% while that of TPU‐4 was increased to 27.5% and reached to V‐0 rating on the vertical burning test. Thermogravimetric analysis (TG) indicated that containing both APP and citrate accelerated the degradation of TPU composites but increased the char residue. In detail, the char residue of TPU‐0 was 6.3 wt% at 685°C, while that of TPU‐3 was reached to 45.2 wt% at N 2 atmosphere. Laser Raman spectroscopy (LRS) showed that the degree of graphitization of TPU composites had been increased after adding the citrates. X‐ray photoelectron spectrometer (XPS) and gas chromatography/mass spectrometry (GC‐MS) illustrated that citrate and APP exerted barriers effect in the condensed phase. This work provided a new way of flame retardant that integrated with citrate and APP for TPU composites.