A main-chain phosphorus-containing poly(trimethylene terephthalate) copolyester: synthesis, characterization, and flame retardance

In order to improve the flame retardancy of the semi-biobased polyester, poly(trimethylene terephthalate) (PTT), bis-4-carboxyphenyl phenyl phosphine oxide (BCPPO) was used as a third monomer to synthesize a novel main-chain phosphorus-containing copolyester, poly(trimethylene terephthalate-co-BCPPO)s (PTTBP), through melt polycondensation. Phosphorus analysis of the resulting polymers suggests that BCPPO has been introduced to PTT chain successfully. 1H and 31P nuclear magnetic resonance spectra further confirm the random chemical structure. The thermal behavior was investigated by differential scanning calorimetry and thermogravimetric analysis. The introduction of BCPPO to PTT lowered the melting point and crystallization ability because of the random copolymerization and the rigid structure of BCPPO, and the thermal stabilities of PTTBP were improved in air but decreased in nitrogen. Rheological investigations showed that the complex viscosities of all the samples were independent of frequency at low frequency (say lower than 100?rads), and shear thinning effect occurred at higher frequency. The cone calorimeter was used to test the fire behavior of PTTBP, and the results suggested that the novel copolyester had good flame retardance. Copyright (c) 2011 John Wiley & Sons, Ltd.