Tsapko O. Protection of wood with intumescent coatings

The dissertation is dedicated to the solution of an actual scientific and technical problem which lies in the prevention of the thermal decomposition of wood used in building structures based on the revelation of the mechanism of slowing down of the burning process and raising of the serviceability in case of wood protection with intumescent coatings. Analyzing of physiochemical properties of wood made it possible to identify the advantages and disadvantages of wood as a structural material. The most common defect of wood was distinguished, namely the ability of its structure not to resist the fire flux which causes high risk of fire hazard. Review of methods and means of fire retardant treatment of wood was conducted. Principal effective means were classified upon information processing. Their drawbacks and advantages were highlighted. The most effective compositions for wood fire retardant treatment were identified and their disadvantages were revealed, namely: high toxicity, high smoke-forming ability, unavailability of any resistance to flame spreading across the surface, and ability to crumble over time and delamination of the coatings based on the compositions. Specific features of expanded coke coating formation as well as influence of the components being its constituent parts on the expansion process were revealed. Application of special catalysts, hydrocarbons, gas forming compounds and binding agents capable of forming protective expanded coke layer in the intumescent coatings was substantiated. Role of a mineral additive in the structure of the fire protective coating capable of reacting with coating components in case of high temperature exposure and form ceramic-like compounds which can withstand vigorous thermal exposure was revealed. Necessary condition of ensuring fire retardant treatment efficiency is the determination of any principal transformations (flammability, combustibility, flame spread, smoke-forming ability and toxicity of fire effluents) combined with the environmental and serviceability performance. Simulation of the process of propagation of the phase conversion front was conducted for the time of expansion of the fire protective coating and some calculation relationships were derived which allow forecasting changing of the expansion dynamics of the fire protective coating under elevated temperature exposure conditions. Using derived relationships we calculated duration of expanded coke formation at the time of thermal decomposition of the coating which equals to 2.2 s. Physical model of wood ignition and its mathematical interpretation were developed specific feature of which was availability of heat evolution (absorption) rate at the time of thermal decomposition of the material and index of the rate of thermal decomposition causing deceleration of burning reactions when applying fire protective coating. It was revealed that upon wood exposure to high temperature its ignition was initiated with the high temperature development. It was revealed that for the specimens having not been subjected to fire protective treatment index of burning development was equal to 0.0152 s^–1, and index of burning cessation was 0. It was revealed experimentally that introduction of some mineral fillers to the organic and mineral composition in the amount of 10 % promoted enlargement of expansion factor from 30 to 36.7 which was 1.5 to 1.84 times higher than expansion factor of the organic and mineral composition of optimum formulation containing no fillers. A comprehensive approach was developed to the estimation of fire resistance performance by indices of flammability, combustibility and smoke forming ability. Research of efficiency of fire retardant treatment of wood tare used for explosives storage was conducted; it was established that a specimen having not been treated was capable of catching fire and spreading flame across its surface; these facts lead to operation of pyrocartridges and collapse of the construction. revealed that the specimen having been treated with intumescent coating prevented more efficiently influence of high temperature influence and wood charring compared with coatings based on organic compounds mechanism of effect of those was purposed at heat insulation due to formation of expanded coke layer. Calculation of the amount of the materials necessary for the fire retardant treatment of chemicals storage rooms belonging to “Zakhysni pokryttia” SME area of those equals to 8,400 m^2 was conducted for the case of “FIREWALL-WOOD” fire protective coating as well as “Phoenix-DB” coating being the most widely used agent for fire retardant treatment of wood. We revealed that economical effect due to introduction of the developed agent was equal to UAH 1,811,712.00 whereas that due to introduction of the alternative option was equal to UAH 607,488.