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Abstract: Fire retarded poly(ethylene terephthalate) (PET) has been obtained by the incorporation of octamethyl polyhedral oligomeric silsesquioxane (OMPOSS) and Exolit OP950, a phosphinate-based compound, in recycled PET. The presence of Exolit OP950 only leads to intumescence explaining the improvement of the flame retardancy. The addition of OMPOSS leads to a synergistic effect considerably increasing the fire retarding performances of the polymer in terms of cone calorimetry and limiting oxygen index even if a small thermal stabilisation as well as a very poor dispersion of OMPOSS and OP950 into the matrix has been observed. [Copyright &y& Elsevier]

Abstract: The aim of this work is to better understand the role and the mechanism of action of boric acid and of coated ammonium polyphosphate (pure ammonium polyphosphate coated with THEIC) used as flame retardants in a commercial intumescent epoxy-based formulation using analytical techniques including thermogravimetric analyses (TGA) and solid-state NMR. In a previous paper, we detected that some reactions took place during the intumescence phenomenon between boric acid and ammonium polyphosphate upon heating. The paper focuses on the analysis of the degradation of those sole components and on the study of their interaction. It is first shown that the THEIC increases the thermal degradation rate of ammonium polyphosphate. This enables the degradation products of boric acid and coated ammonium polyphosphate to react together, resulting in the formation of borophosphate. It is suggested that the formation of this product provides the superior mechanical resistance of the char and promotes the adhesion of char on the steel plate. [Copyright &y& Elsevier]

This work investigates the fire retardancy, the thermal and thermomechanical properties of PP/PC blends using commercially available grafted polyolefins with functional groups as compatibilizing agent. In the first part, the effect of compatibilizer on the morphology has been correlated with the thermomechanical properties. The blends, containing 75% of PP and 25% of PC or 22% PC plus 3% compatibilizer have been prepared during the melt processing in a mixer. The compatibilizers were grafted maleic anhydride polypropylene (PP‐g‐MA) and a terpolymer ethylene/acrylic ester/maleic anhydride (EBuAMA). The thermal stability was improved up to 400°C when using compatibilizer in comparison with PP/PC blend. The thermomechanical properties were improved for PP/PC/PP‐g‐MA blend. It was found that the addition of compatibilizer slightly decrease the particle size of the minor PC phase. The crystallization temperature of PP in PP/PC/PP‐g‐MA increases which may explained the improvement of the properties of the blend in comparison with PP/PC/EBuAMA. In a second part, fire retardant formulation are developed. The fire retardant properties of the blend are slowly affected by the presence of a compatibilizer. [ABSTRACT FROM AUTHOR]

This study deals with the fire retardant performance of vinyl acetate (VA)/butyl acrylate (BA) copolymers using phosphorus compounds as additive or as co-monomer. First, VA/BA copolymer has been mixed with phosphorus additives from various sources: red phosphorus, organo-phosphates, organo-phosphonate, inorganic phosphate and an intumescent system (ammonium polyphosphate and pentaerythritol). The incorporation of 5 wt.-% phosphorus leads to VA/BA copolymers with improved fire properties whatever the source of phosphorus used. The best performance is achieved with the intumescent system. Second, VA and BA monomers have been copolymerised with phosphorus monomers (phosphate and phosphonate). Both systems present fire retardancy of interest. The better performance is achieved using phosphonate. Both systems are assumed to work in the condensed phase. [Copyright &y& Elsevier]

The present work is dedicated to the development of a new method, which enables a better understanding of the intumescence process. Many studies have investigated char formation from a chemical aspect but the foaming and strength of the char have not been well studied before. Thermal scanning measurements using a rheometer as a fire reactor enable a correlation between the fire behaviour and thermal behaviour and the visco-elastic properties of the material. This study investigates the rheological modifications of polyurethane thermoset coatings with or without fire-retardant. The rheological and mechanical destruction properties of the protective char layer have been correlated with their fire retardant performance for two additives: ammonium polyphosphate and expandable graphite. In a first part, the expansion of pure PU and of intumescent materials under normal force is studied. Then, the visco-elastic behaviour is investigated in order to evaluate the different steps of the intumescent process (development, stability and destruction). Finally, mechanical properties of the intumescent chars are discussed. [Copyright &y& Elsevier]

This paper aims at developing an innovative approach to characterize the char residue of an intumescent coating obtained after a UL1709 furnace test. The intumescent formulation is based on an epoxy resin and contains numerous additives including zinc borate, ammonium polyphosphate and silicate fibers. The purpose is to characterize the numerous reactions that can occur upon burning using crossed methods including Electron Probe Micro-Analysis (EPMA), X-ray diffraction (XRD) and 1D/2D solid state Nuclear Magnetic Resonance (NMR). In particular, it emphasizes the potential of the advanced NMR technique namely two-dimensional Dipolar Heteronuclear Multiple Quantum Correlation (2D D-HMQC) NMR. As a result, EPMA evidenced that B/P and B/Si are located in the same domain suggesting the formation of boron-phosphorus and/or boron-silicone containing compounds on the sample surface. H 3 BO 3 was identified by XRD as a main crystalline specie, additional species (e.g. SiO 2 , Zn 4 O(BO 2 ) 6 ) were also identified. The borate, silicate and phosphate chemical species were then characterized using 1D NMR but no definitive assignments could be given. To specify those assignments, 2D D-HMQC NMR was performed and the formation of amorphous borophosphates and borosilicates was evidenced emphasizing the chemical reactivity between the ingredients of the formulation. It was suggested that these species allow reinforcing the char and improving the fire protective properties of the coatings. This work highlights the particular interest of advanced NMR technique, which provides unique information on the characterization of intumescent char. [ABSTRACT FROM AUTHOR]

• A flame retardant and weathering resistant self-stratified coating is designed. • Epoxy stratifies as the base layer and silicone as the upper layer. • Iron oxide and Calcium carbonate fillers migrate to the silicone phase. • The filled coatings yield V0 rating at UL94, high LOI and rise time to ignition at MLC. • The filled coatings are stable under UV, humidity and temperature aging procedures. Lowering fire hazard raised by combustible materials such as plastics may be achieved by the use of suitable flame retardant treatments, like fire protective coatings. However, exposure to long-term environmental conditions can cause loss of their functional properties, thus reducing their effectiveness over time. This is why two or three different layers with specific properties (e.g. adhesive, fire retardant and hydrophobic) are generally needed to provide durable fire retardancy. Effective and economical self-layering coatings can be developed to reduce the number of layers without compromising the advantages of the actual system. In this work, the efficiency of applying a silicone based coating to fire retard polycarbonate and the modification of the behaviors of the system, using a mixture of epoxy/silicone resins, a curing agent and either iron oxide or calcium carbonate as fire retardant filler is investigated. Self-stratification and fillers dispersion were evidenced by microscopic analyses coupled with chemical detection, the flame retardant properties using Limiting Oxygen Index (LOI), UL-94, Mass Loss Calorimetry (MLC), Thermogravimetric analyses (TGA) and a tubular furnace, and aging resistance by accelerated thermal, humidity and UV exposure. It appears that the selected fillers have no negative effect on the layering process when introduced from 2.5 to 10 vol.%: perfect stratification is obtained, with the silicone layer being the top layer. The best improvements in terms of fire retardant properties, adhesion and fillers dispersion were obtained by incorporating 2.5 vol.%: V0 rating at UL-94 and 33 and 35 vol.% at LOI with Fe 2 O 3 and CaCO 3 respectively were measured when a 200 μm wet thick coating was applied. The coating containing iron oxide was unaffected by weathering conditions. Finally, the application of those coatings on polycarbonate allows the formation of a protective barrier which limits substrate/flame mass transfers. It therefore results in (i) a delay of the time to ignition, (ii) the inhibition of the flame spread and of dripping when submitted to a flame, and (iii) a reduction of the combustibility of polycarbonate. A modification of the structure of the silica network formed by the particles which enhances the barrier effect of the silicone-based layer would be the most probable assumption to explain these excellent results. [ABSTRACT FROM AUTHOR]