Serge Bourbigot

Comprehensive study of the degradation of an intumescent EVA-based material during combustion

In this work, we have studied the evolution of an flame retardant intumescent EVA-based material during combustion. The formulation uses an original concept of the laboratory, i.e., use of char forming polymer (here the polyamide-6) as carbonisation agent associated to a carbonisation catalyst in an intumescent formulation. The fire behavior was modelled using the cone calorimeter and we have explained the evolution of the rate of heat release curve in terms of chemistry of the system using FTIR and solid state NMR.

Fire Degradation of an Intumescent Flame Retardant Polypropylene Using the Cone Calorimeter

This work studies the fire degradation of an intumescent for mulation Polypropylene (PP)-Ammonium Polyphosphate (APP)/Pentaerythri tol (PER) using the cone calorimeter. An intumescence model is described which introduces the notion of degradation front. From the weight loss data recorded by the cone calorimeter and the results of the invariant kinetic pa rameters method (given in appendix) applied to the PP and to the PP-APP/PER system, the respective temperatures of the degradation fronts are measured. A stability zone is shown where the protection is effective. The intumescent coating degrades then by forming a carbonaceous residue which reduces the heat flux evolved.

Characterization of a polyamide-6-based intumescent additive for thermoplastic formulations

Abstract Charring polymers may be used as carbonization agents in fire retardant (FR) intumescent additive master batches. This paper presents typical polyamide-6-based master batches which are extensively used in polyethylenic FR formulations. It is shown that a blend of polyamide-6 and an ethylene–vinyl acetate copolymer allows the incorporation of the carbonization catalyst, i.e. ammonium polyphosphate, in the polymeric material. The problem of the migration of the phosphate throughout the polymeric matrix is discussed. Solid state NMR spectroscopy is presented as a tool to predict and to explain the part played by the interfacial agent, i.e. the functionalized polymer.

Fire behaviour related to the thermal degradation of unsaturated polyesters

In this work, the thermal and the fire behaviour of unsaturated polyester (UP) resins have been investigated. A comparison of the thermal stability of the two materials (UP resins without and with modification with DCPD grafted on the chains ends) showed that the resin with DCPD is more stable. Nevertheless, modelling of the fuel flow evolved during the degradation showed that it is faster in the case of the material with the DCPD. It is related to the formation of char which must be developed to provide protection to the underlying polymer. This assumption was then confirmed by measurement of the temperature profiles using the cone calorimeter and by the evolution of the degradation front which showed that the thermal transfer was reduced in the case of the resin with DCPD.

The Thermal Behaviour of a Blend of Cotton and Fire-retardant Polyester Fibres: A Kinetic Study

This work compares the thermo-oxidative degradation of cotton and fire-retardant polyester-fibre (PESFR) fabrics and that of a cotton/PESFR blend. The association in a blend of PESFR with cotton fibres improves the burning behaviour of the latter. The invariant-kinetic-parameter (IKP) method allows one to modelise the degradation of the material, and in particular to compute the degradation velocity. We demonstrate that the ‘fuel-flow’ rates give rise to the fire retardancy of the materials and that the latter, in this case, does not depend on the nature of the gases evolved.

Thermal Degradation Behaviour of Flame-Retardant Unsaturated Polyester Resins Incorporating Functionalised Nanoclays

This paper discusses the effect of nanoclays on thermal degradation of unsaturated polyester resin with and without conventional flame retardants. Unsaturated polyester nanocomposites were prepared by in-situ polymerization with exfoliated structures. Simultaneous DTA-TGA analysis showed that nanoclays reduce thermal stability of the unsaturated polyester resin below 600C and after that there was no change. Nanoclays also reduce the onset of degradation temperature of the resin. Above 600 C, char formation is enhanced but not to the same extent as reported in literature for other polymer (e.g., nylon, polystyrene, etc.) – nanocomposite structures. The effect of conventional flame retardants ammonium polyphosphate, melamine phosphate with and without dipentaeythritaol and alumina trihydrate on thermal degradation of resin was also studied. All these flame retardants enhance char formation of the resin above 400C and presence of nanoclays promotes further increase. Analysis of the thermogravimetric data indicates that this enhancement in char formation is not as much as expected when compared with similar other polymer nanocomposite structures.  Corresponding author. Tel.: +44-1204-903517 ; fax: +44-1204-399074. E-mail address: bk1@bolton.ac.uk “Thermal degradation behaviour of flame retardant unsaturated polyester resins incorporating functionalised nanoclays”, B K Kandola, S Gawande and A R Horrocks, in “Fire Retardancy of Polymers: New Applications of Mineral Fillers”, eds M Le Bras, C A Wilkie, S Bourbigot, S DuQuesne and C Jama, Royal Society of Chemistry, London, 2005, pp 147-159 2

Investigation of the Contribution to Fire of Electrical Cable by a Revisited Mass Loss Cone

This paper deals with a new bench-scale test allowing to investigate the contribution to fire of materials and more particularly manufactured products such as electric cables. This study focuses on halogen-free flame retardant (HFFR) cables. This bench-scale test is composed of a mass loss cone, Fourier transform infrared spectroscopy, and electrical low-pressure impactor (MLC/FTIR/ELPI). It allows determining flammability parameters, gases released and particles in the smoke. The HFFR cables’ main flammability parameters obtained are as follows: the HRR measured at external heat fluxes lying from 25 to 75 kW/m2 exhibits similar behavior composed of a highest peak of heat release rate (pHRR) just after ignition then a second pHRR close to flame out. It is noteworthy that pHRR is not modified (120 ± 10 kW/m2) whatever the studied heat flux. The total heat released during combustion is about 126 ± 2 MJ/m2 with an average effective heat of combustion (AEHC) of around 25 ± 4 MJ/kg. The critical heat flux (CHF) was evaluated to be 10.5 kW/m2. The yields of the gases released are as follows: 4.4 g CO2/g HFFR cable, followed by H2O (3.5 g H2O/g HFFR cable), CO (0.1 g CO/g HFFR cable), and CH3COCH3 (0.07 g CH3COCH3/g HFFR cable). The particles emitted in the smoke are in the submicron size range. This study indicates that MLC/FTIR/ELPI coupling can be applied with confidence to a manufactured product such as electrical cable.

Flame-retardant polypropylene compositions

Economical manufacturing methods of mass production and improvements to the properties of finished products have in many applications greatly helped to replace traditional materials, such as metals or wood, with plastics and rubbers. In particular, polypropylene (PP) is the fastest growing commodity plastic world-wide. It has found its place in many sectors such as building, transportation (automotive, railways, etc.), electrical engineering (electrical/household appliances, housings, etc.) or paper industry.