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8179103 
Journal Article 
Dynamic FTIR studies of thermo-oxidation of expandable graphite-based halogen-free flame retardant LLDPE blends 
Xie, RC; Qu, BJ; Hu, KL 
2001 
1 
Polymer Degradation and Stability
ISSN: 0141-3910 
ELSEVIER SCI LTD 
OXFORD 
72 
2 
313-321 
English 
WOS:000168109900015 
The dynamic thermo-oxidative degradation of expandable graphite (EG)-based intumescent halogen-free flame retardant (HFFR) LLDPE blends in the condensed phase at 300 or 400°C has been studied in situ by real time Fourier transform infrared spectroscopy. The kinetic characteristics and dynamic changes of various kinds of pyrolysis products during the thermo-oxidative degradation were examined extensively for several LLDPE/EG blends with different HFFR additives, such as the phosphorus-nitrogen compound NP28, ammonium polyphosphate (APP), red phosphorus (RP), and zinc borate (ZB). It has been found (i) that the dynamic monitoring of the LLDPE/EG/HFFR blends during the pyrolysis shows that the breakdown of LLDPE main chains and formation of various kinds of carbonyl products increase with increasing thermo-oxidation time and temperature; the latter have been identified as carboxylic acids, ketone, lactone and cyclic anhydrides; (ii) that the fast formation rate and high initial concentrations of P-O-P and P-O-C products in the phosphorus-containing HFFR systems have a crucial importance for decreasing the thermo-oxidative degradation rate of LLDPE efficiently (the NP28 system is the most efficient in the present study); and (iii) that the pyrolysis temperature has a significant effect on the efficiency of flame retardants, which requires the LLDPE/EG/HFFR formulation should be optimized at certain temperature range in order to form compact intumescent charred layers immediately at the beginning of the thermo-oxidative degradation of the LLDPE blends. © 2001 Elsevier Science Ltd. 
dynamic thermo-oxidative degradation; LLDPE; expandable graphite; halogen-free flame retardant; real time FTIR; flame retardant mechanism