Intumescent polypropylene in extreme fire conditions (original) (raw)
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Effect of Fillers on the Fire Retardant Properties of Intumescent Polypropylene Compounds
Polymers and Polymer Composites, 2008
The effects of fillers, including ammonium polyphosphate (APP), aluminium trihydrate (ATH) and talc, and the effect of polyethylene vinyl acetate (EVA) as an interfacial agent, were investigated on the flame retardant properties of intumescent polypropylene (PP), by using mechanical testing, to measure the tensile and Izod impact strengths, thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and the limiting oxygen index (LOI) test method. SEM studies showed that the dispersion of flame retardant particles in the PP matrix improved with the use of EVA. Tensile strength decreased but elongation at break and impact resistance of PP/APP/EVA and PP/ATH/EVA composites increased by using 10 wt.% of EVA. Using 12 wt.% of talc in PP/APP/PA-6/EVA led to increasing impact resistance and decreasing tensile strength and elongation at break of the composite. EVA prevented the exudation of additives to the composite surface, and consequently the fire retardant properties of the c...
Polymer Degradation and Stability, 2013
This paper describes the effectiveness of novel phosphorousenitrogen intumescent flame retardant system (ammonium polyphosphate 202 and PPM Triazine HF e trademark, abbrev. IS) on fire retardancy and thermal stability properties of polypropylene (abbrev. PP) at incorporation level below the standard amount required for intumescent flame retardant system. UL-94 vertical burning test revealed that the addition of 20 wt.% of IS into neat PP is enough to reach V-0 rating (short burn without dripping). Further, a higher increase of the oxygen concentration for ignition was also found with the addition of the novel intumescent flame retardant to neat PP; LOI value of neat PP by addition of 20 wt.% IS rose from 19 to 31 vol.%.
Intumescent polypropylene: Reaction to fire and mechanistic aspects
Fire Safety Journal, 2019
The concept of intumescence was applied to make flame retarded polypropylene (PP). This paper examines two types of intumescence in PP based on expandable graphite (EG, physical expansion) and on modified ammonium polyphosphate (AP760, chemical expansion). Reaction to fire of PP containing EG and AP760 was first evaluated by cone calorimetry. The incorporation of intumescent additives at relatively low loading (10 wt%) in PP permits the reduction by 70% of peak of heat release rate (pHRR). The mode of action occurs via the formation of an expanded carbonaceous layer in all cases. The protective coating acts mainly as heat barrier in the case of the formulations containing AP760 or as heat dissipater with EG. The incorporation of small amount of EG in PP-AP760 modifies heat transfer in the coating creating a strong anisotropy. Upon expansion, graphite worms align normal to the surface increasing the transverse heat conductivity (lower efficiency of the heat barrier) and hence, decreasing the fire performance (decrease by only 30% of pHRR). Kinetic analysis was then performed to quantify the thermal stability of the intumescent systems. It reveals that the intumescent additives do not modify the reactional scheme of the PP thermal decomposition but they increase slightly the thermal stability of the intumescent systems. For all materials, the decomposition model follows a reactional scheme at two successive reactions. This model was determined in dynamic conditions (conditions of thermogravimetry with linear heating rates) but it is able to simulate the decomposition of the materials in isothermal conditions (excellent agreement between the simulated and experimental curves).
International Journal of Polymer Science, 2015
The effect of particle size reduction of the components of a common intumescent flame retardant system, consisting of pentaerythritol (PER) and ammonium polyphosphate (APP) in a weight ratio of 1 to 2, was investigated on the flammability and mechanical performance of flame retarded polypropylene (PP) compounds. Additives of reduced particle size were obtained by ball milling. In the case of PER, the significant reduction of particle size resulted in inferior flame retardant and mechanical performance, while the systems containing milled APP noticeably outperformed the reference intumescent system containing asreceived additives. The beneficial effect of the particle size reduction of APP is explained by the better distribution of the particles in the polymer matrix and by the modified degradation mechanism which results in the formation of an effectively protecting carbonaceous foam accompanied with improved mechanical resistance. Nevertheless, 10% higher tensile strength was measured for the flame retarded PP compound when as-received APP was substituted by milled APP.
Polymers for Advanced Technologies, 2008
Melamine salt of tripentaerythriol phosphate (MTP), as a new intumescent flame-retardant, was prepared from tripentaerythritol (TPE), polyphosphoric acid, phosphoric pentoxide, and melamine, and then incorporated into polypropylene (PP) to obtain flame-retarded PP-MTP. FT-IR analysis showed that MTP was in the form of cage structure. The flammability, combustion behavior, and thermal degradation and stability of flame-retarded PP were characterized by using LOI, UL-94 test, cone calorimetry, and TGA, respectively. By SEM, the char structure of PP-MTP was analyzed. XRD diffraction tests showed that PP-matrix of PP-MTP presented better crystallized phases, when MTP was modified by methyl hydrogen siloxane. The relations of the dispersion of MTP in PP matrix to the compatibility between PP and MTP, and to the flame retardancy were discussed.
Journal of Applied Polymer Science, 1985
The action of some mixtures of ammonium polyphosphate (APP) and polyurethanes (PUr) as flame retardant (FR) agents for polypropylene (PP) was examined. The APP-PUr systems behave as intumescent flame retardant (IFR) formulations. The IFR action of these systems is described by the comparison of the oxygen index (01) values measured on molded pellets and on molded rods, by measurements of the polymer temperature just below the burning surface and by visual observations. A strong synergism between APP and some polyurethanes, having piperazine units in the polymer chain, was ascertained with a maximum 3:l ratio. Our results also indicate that only polyurethanes with specific structure, in combination with APP, are active as IFR agents on PP combustion.
Polymer Degradation and Stability, 2013
Recently, noticeably enhanced flame retardancy of multilayered self-reinforced composites, flame retarded with common ammonium polyphosphate based intumescent system, was described. In this paper the observed novel flame retardant synergism between intumescent additive system and highly oriented polymer fibres is further studied. The ignitability and combustion behaviour of flame retarded multilayer self-reinforced composites were compared to flame retardant compounds, prepared by simple melt compounding, of identical low additive contents, both when the heat was applied parallel (UL-94 tests) and perpendicular (cone calorimetric tests) with the direction of the embedded oriented tapes in self-reinforced composites. SEM and EDS analyses supported the different foaming process of the two types of samples to be understood, while the structure and character of the finally (after combustion) obtained charred layers were examined by compression tests. Considering the results of all the applied testing methods, the complex picture of the mechanism behind the enhanced flame retardant efficiency of flame retarded self-reinforced composites could be clarified.
Open Chemistry, 2021
In many plastic applications, improvement of the flame retardancy is a very significant topic. Polypropylene (PP) is used in many applications such as housing industry due to its cost performance efficiency. Enhancement of flame retardancy properties of PP is necessary in many applications. In this study, the investigation focuses on the synergistic effect of mica mineral and IFR in enhancing the flame retardancy properties of PP in order to achieve cost competitive solution, so as to provide that different/various ratios of IFR and mica mineral were added into PP to compose 30 wt% of the total mass of the polymeric compounds. The synergistic effect of mica mineral with IFR in PP was investigated by limiting oxygen index (LOI), glow wire test (GWT), UL-94 test, thermal gravimetric analyses (TGA), and mechanical tests. The results from LOI, UL 94, and GWT tests indicated that mica added to PP/IFR compound has a synergistic flame retardancy effects with the IFR system. When the conten...
Polymers for Advanced Technologies, 2008
Intumescent systems have been developed since many years for a wide range of applications, even if they are mainly used in coatings nowadays. The objective of this paper is to determine if the intumescent concept can be applied to highly filled reinforced polypropylene (PP) composites containing talc. Formulations that meet the electrical industry requirements have been developed, even if it has been observed that the addition of talc into intumescent PP leads to a decrease in the fire retardancy of the systems. A thermal stabilization of the material is noted at high temperature in the presence of talc. An increase in the crystallinity of the intumescent structure is suspected to be, at least partially, responsible for the decrease in the performance.
Comparison of fire resistance of polymers in intumescent coatings for steel structures (1)
Thermal destruction of fire-retardant intumescent coating of the composition of ammonium polyphosphate (APP)/melamine (MA)/pentaerythrite (PE)/titanium oxide (TiO 2)/polymer, which can be applied for fire protection of steel structures, was studied. The influence of polymers of different nature-ethylene-vinyl acetate (EVA), vinyl acetate versatate (VAVV), styrene acrylates, and vinyl toluene acrylate on the processes of formation of a coke layer and fire-retardant effectiveness of appropriate coatings was determined. Chemical transformations of polymers EVA and styrene acrylate in the intumescent system of ARR/MA/ PE/TiO 2 in the temperature range of 200-800 °С were studied. It was established that the processes of the thermal destruction of vinyl acetate polymer are more harmonized with chemical reactions of the components of the intumescent system than similar processes for acrylate aromatic polymers. Thermal-oxidation destruction of intumescent compositions at the temperatures of 200-800 °С was explored. It was shown that basic chemical processes with polymers of EVA and VAVV begin after 300 °С and flow in the temperature range of 350-600 °С. It was found that the noticeable degradation of the carbon-phosphorus frame of intumescent compositions with styrene acrylate polymers begins at 450 °С, which is almost by 150 °С below the temperature of degradation of the compositions containing vinyl acetate binders. The conducted fire tests demonstrate that intumescent compositions with the use of acrylate aromatic polymers are more effective at the low coating thickness in ensuring the fire resistance boundary of 30 min. In order to ensure higher values of fire resistance, it is necessary to use intumescent coatings containing vinyl acetate co-polymers as the polymer component. The study of the impact of polymers of intumescent coatings on the boundary of fire resistance of steel structures has scientific and practical significance for the development of differentiated fire protection means, oriented to the given class of fire resistance. Fire-retardant intumescent compositions examined in this study can be used as the basis for the formulations of materials for fire protection of building structures under conditions of a standard fire