No abstract

Three kinds of organic intercalation agent containing flame retardant groups, melamine (MA), triphenylphonium (TPP) chloride, and tetradecyl trihexyl phosphonium (TTP) bromide were intercalated into montmorillonite (MMT) via cation exchange reactions. These modified MMTs are combined with intumescent systems and compounded with PP. The flame retardant and thermal properties of the PP composites are studied. The organic intercalation agents in the layers of MMT play important roles in the char formation and flame retardant properties of PP composites. MA shows a better performance in limiting oxygen index (LOI) value and TPP helps to increase UL‐94 properties, whereas TTP maintains or deteriorates the flame retardancy of polypropylene/intumescent flame retardant (IFR) composites. The LOI and UL‐94 properties increase firstly and then decrease as the content of MMT increases. The MA acts as a blowing agent and emits an inert gas to provide migration impetus, which results in a better intumescent structured and stronger char to endure heat erosion. Although TPP and TTP emit combustible gas that burn, especially for TTP as it has a more flammable aliphatic chain. The synergistic effect between MA‐MMT and IFR is better than that for TPP‐MMT and TTP‐MMT. Copyright © 2014 John Wiley & Sons, Ltd.

A novel phosphorus-containing poly (ethylene terephthalate) (PET) copolyester/nano-SiO 2 composite (PET-co-DDP/SiO 2 ) was synthesized by in situ polycondensation of terephthalic acid (TPA), ethylene glycol (EG), [(6-oxide-6H-dibenz[c,e] [1,2]oxaphosphorin-6-yl)-methyl]-butanedioic acid (DDP), and nano-SiO 2 . The morphology of PET nanocomposites was observed by using transmission electron microscope and scanning electron microscope. It was found that the SiO 2 nanoparticles were dispersed uniformly at nanoscale in the copolyesters with content 2 wt %. The thermal degradation behavior of PET nanocomposites was investigated by thermogravimetric analysis performed with air and nitrogen ambience. The activation energies of thermal degradation were determined using Kissinger and Flynn-Wall-Ozawa methods, respectively. The results obtained from Kissinger method showed that the activation energy was increased with the introduction of SiO 2 . Moreover, the activation energy is decreased for PET-co-DDP system in nitrogen and air. The results also indicated that the SiO 2 and DDP had synergic effect on the early decomposition and the late charring in air. Furthermore, in the PET-co-DDP/SiO 2 system, the activation energy increased when the DDP component increased. However, the opposite results were obtained when the Flynn-Wall-Ozawa method was used. That was because the Doyle approximation stands correct as the conversion degree is from 5% to 20%. The effects of SiO 2 and DDP on the PET thermal degradation were lower in nitrogen than in air.