A Study of Thermal Degradation and Fire Behaviour of Polymer Composites and Their Gaseous Emission Assessment

Phosphorus/Bromine Synergism Improved the Flame Retardancy of Polyethylene Terephthalate Foams

Polyethylene terephthalate (PET) foams have the characteristics of being lightweight and high strength, as well as offering good heat resistance, minimal water absorption, etc., and they have been widely used in the wind power field. In addition, they are being promisingly applied in automotive, rail, marine, construction, and other related fields. Therefore, the flame retardancy(FR) of PET foams is an issue that requires investigation. The addition of flame retardants would affect the chain extension reaction, viscoelasticity, and foamability of PET. In this study, zinc diethyl hypophosphite (ZDP) and decabromodiphenylethane (DBDPE) were used to form a synergistic FR system, in which ZDP is an acid source and DBDPE is a gas source, and both of them synergistically produced an expanded carbon layer to improve the flame retardancy of PET foams. The ratio of ZDP and DBDPE is crucial for the carbon yield and the expansion and thermal stability of the char layers. At the ZDP/DBDPE ratios of 9/3 and 7/5, the thickness of the char layers is about 3-4 mm, the limiting oxygen index (LOI) values of FR modified PET are 32.7% and 33.6%, respectively, and the vertical combustion tests both reached the V-0 level. As for the extruded phosphorous/bromine synergism FR PET foams, ZDP/DBDPE ratios of 3:1 and 2:1 were applied. As a result, the vertical combustion grade of foamed specimens could still reach V-0 grade, and the LOI values are all over 27%, reaching the refractory grade.

Flame Retardant Coatings: Additives, Binders, and Fillers

This review provides an intensive overview of flame retardant coating systems. The occurrence of flame due to thermal degradation of the polymer substrate as a result of overheating is one of the major concerns. Hence, coating is the best solution to this problem as it prevents the substrate from igniting the flame. In this review, the descriptions of several classifications of coating and their relation to thermal degradation and flammability were discussed. The details of flame retardants and flame retardant coatings in terms of principles, types, mechanisms, and properties were explained as well. This overview imparted the importance of intumescent flame retardant coatings in preventing the spread of flame via the formation of a multicellular charred layer. Thus, the intended intumescence can reduce the risk of flame from inherently flammable materials used to maintain a high standard of living.

The Effect of Different Modifying Methods on Physical, Mechanical and Thermal Performance of Cellular Geopolymers as Thermal Insulation Materials for Building Structures

Geopolymers represent a new class of inorganic materials that have great potential for practical application due to the properties of used raw materials, as well as the peculiarities of the cementitious matrix structure formed during the geopolymerization process. Cellular geopolymer specimens were produced in this study using class F fly ash product, which is characterized by low reactivity during geopolymerization. Several standard methods, as well as microstructural studies were applied to evaluate the effect of the following factors on the physical-mechanical and thermophysical characteristics of cellular geopolymers: the use of various mineral modifying components for synthesis of geopolymer systems; high-temperature treatment; the introduction method of alkaline activator. It was observed that “ageing” an aqueous alkali solution for 24 h before mixing with fly ash and foam agent was able to provide a boost of compressive strength of cellular geopolymer specimens up to about 2.5 times, while decreasing the average density by about 28% for all experimental mixes, except for PC-modified mixes. Additionally, high-temperature treatment at 600 °C enables an enhanced strengthening effect of pore structure in cellular geopolymer matrix up to 1.5 times. This phenomenon is especially pronounced for the mixes with 24 h “aged” alkaline solution with exception for PC-modified mixes; for those, high-temperature treatment at 600 °C leads to strength decrease up to 40%. The introduction method of alkaline activator and high-temperature treatment showed a controversial effect on thermal conductivity coefficient depending on the mineral modifying component used for the synthesis of cellular geopolymers. The proposed method for calculation of total porosity of cellular structure of geopolymers as a polycomponent material demonstrated a high degree of correlation with the R2 value of at least 0.96 between the average density and the calculated total porosity. However, a low degree of correlation with R2 not exceeding 0.29 was observed for the measured nanoporosity, regardless of the introduction method of alkaline activator and high-temperature treatment.

Formation of ANFO Analogues under Fire Conditions in the Presence of Common Plastics

This article is a continuation of a case study in which we presented the results of research on processes generated under fire conditions by mixing molten ammonium nitrate (AN) with selected polymers. Here, we present an analysis of how certain materials, which may frequently appear in farm buildings and are commonly used in the immediate vicinity of humans, can potentially form explosives. The chosen materials include polyamides (PA) from which the wear-resistant machine elements are made (e.g., high-performance gears, wheels of transport trolleys); polyvinyl chloride (PVC) used, i.e., in construction carpentry, electrical insulation, and hydraulic pipes; polystyrene (PS) used, i.e., in insulation and containers; and poly(methyl methacrylate) (PMMA), i.e., so-called organic glass and plexiglass. The research results showed that these seemingly harmless and safe materials, mixed with AN and heated under fire conditions, may turn into explosives and stimulate stored AN. This creates significant risks of an uncontrolled fire progress.