Polyethylene (PE) was treated with various formulations containing an intumescent fire retardant, which consists of melamine phosphate (MP), pentaerythritol (PER) and ammonium polyphosphate (APP), and one or none of following metal chelates: CuSAO, CoSAO and NiSAO. The behaviour of this intumescent system can be enhanced significantly by the addition of small amounts (0.2%) of metal chelate (CuSAO, CoSAO and NiSAO). The thermal stabilization, burning behaviour and char formation of the fire retardant PE system have been investigated by TGA, LOI, UL-94 test, SEM and cone calorimetry. All formulations studied provide good fire retardant behaviour, with LOI ! 27.4 and UL-94 V-0 rating. TGA results present more complicated thermal decomposition behaviour after the addition of small amounts (0.2%) of metal chelate when compared to that of PE-IFR. Cone calorimetry of PE-IFRemetal chelate (PE-IFReCuSAO, PE-IFReCoSAO and PE-IFRe NiSAO) shows a very significant decrease in HRR, PHRR, ML, THR and a very significant improvement of TTI compared to samples without metal chelate. Furthermore, SEM and photographs of the char layer show that the char layer from PE-IFRemetal chelate has a compact and tough char structure compared to the open porous char layer produced by sample without metal chelate.

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The effect of different concentrations (4 and 8 wt%) of chemically reactive type flame retardant (FR) chemicals on the thermal stability and flammability of an aerospace grade epoxy resin has been studied by thermal analysis, limiting oxygen index, UL‐94, and cone calorimetry. Chemically reactive flame retardant term implies that they interact with the polymer during some part of the pyrolysis and fire chemistries. Flame retardants included (i) phosphorous‐ and nitrogen‐containing, active in condensed phase, (ii) intumescent chemicals, active in condensed phase and also known as char promoters, (iii) organophosphates, active primarily in condensed phase, but in some polymers known to have also shown vapor phase activity, (iv) halogen‐containing, active in vapor phase. During curing process some of the flame retardants settled on the bottom of the resin plaque, affecting the flammability results. All FRs reduced the flammability of the resin, the extent of which depended upon the FR type, concentration of flame retardant elements in the formulation and the type of fire testing performed. With selective FRs, carbon fiber‐reinforced composites have also been fabricated and tested for their fire and mechanical performance. FR chemicals decreased the flammability of composites up to 50% without affecting their mechanical properties. Copyright © 2011 John Wiley & Sons, Ltd.

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A novel trinuclear zinc(II) complex [Zn3L2(μ‐O2CCH3)2(CH3OH)4] (1) that contains an N,O‐donor Schiff base ligand {H2L = 2‐[(2‐hydroxyphenylimino)methyl]‐6‐methoxyphenol} has been synthesized and crystallographically characterized. The X‐ray crystal structure of 1 contains three zinc(II) centers, which have distorted‐octahedral coordination geometry, and the molecule crystallizes in the Pbcn space group. The zinc(II) complex displays significant catecholase oxidation activity in methanolic medium through a ligand‐centered radical pathway. This is the first example of catecholase oxidation through a trinuclear zinc(II)–Schiff base complex by means of the formation of a mononuclear intermediate as [ZnL(dtbc)] (dtbc = 3,5‐di‐tert‐butylcatechol). The fluorescence property of 1 indicates that it can serve as a potential photoactive material. It effectively cleaves the double strand of pBR 322 plasmid DNA at a given concentration (25 μM). The complex shows remarkable cytotoxicity against a human hepatocarcinoma cell line (HepG2).