A novel organic-inorganic hybrid flame retardant (DOPA-ATH), which was prepared via reacting dibenzo [c,e][1,2]oxaphosphinic acid (DOPA) with aluminum trihydroxide (ATH), was incorporated in ethylenevinyl acetate copolymer (EVA) to improve its flame retardance. The structure, morphology and thermal stability of the hybrid flame retardant were characterized by Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The results suggested that DOPA was grafted onto ATH successfully, therefore resulting in higher thermostability than ATH. The flame retardance and burning behaviour of EVA with DOPA-ATH were also studied using limiting oxygen index (LOI), Underwriter laboratory 94 vertical burning test (UL-94 V) and cone calorimeter test (CCT). Results of UL-94 tests and LOI tests showed that the flame retardance of EVA/DOPA-ATH was better than EVA/ATH binary and EVA/DOPA/ ATH ternary flame-retardant composites. The data obtained from the CCT showed that the peak heat release rate (PHRR) of EVA with the addition of 50 wt% DOPA-ATH was reduced by about 25% comparing with EVA with equivalent ATH. Total heat release (THR) and total smoke production (TSP) were reduced remarkably as well. The thermogravimetric analysis (TGA) data showed that the thermal stability of EVA/DOPA-ATH was improved with increased initial decomposition temperature and char residue. SEM observations of cryogenically fractured and tension fractured surfaces showed that EVA/ DOPA-ATH had better interfacial interaction comparing with those of EVA/ATH and EVA/DOPA/ATH, which resulted in better elongation at break and tensile strength.

A series of phosphorus-containing copolyester prepolymers were first sythesized from dimethyl terephthalate (DMT), ethylene glycol (EG), and 2-carboxyethyl (phenyl)phosphinic acid (CEPPA) by molten transesterification and polycondensation, and then solid-state polymerization (SSP) was conducted for different reaction times (t SSP) so as to prepare higher molecular weight copolymers. The intrinsic viscosity was increased with the increase of t ssp, but decreased with the increase of CEPPA content. The sequence distribution of resultant copolyesters was analyzed by 1H NMR. It was found that the randomness of copolyesters was decreased after SSP, and the transesterification occurred mainly at the ester bonds formed by CEPPA and EG, resulting in the chain growth. DSC results showed that SSP treatment was favorable to enhance the crystallization ability of the obtained copolyesters.

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