V. V. Bogdanova’s research while affiliated with Belarusian State University and other places

Polymer thermofoamed composite materials are used for fire protection of structural el-ements in buildings and constructions. Their main disadvantage is their own flammabil-ity at the stage of formation of foamed thermal insulating structures. Increasing the fire resistance of composites requires a systematic study of the factors responsible for re-ducing their flammability characteristics. To develop ways for the targeted creation of low-flammability foamed composite materials, the influence of thermal properties, composition and ratio of fillers introduced into formulations on the flammability char-acteristics of composites was studied. It has been shown that in order to achieve the re-quired flammability characteristics, it is necessary to ensure a balanced fire-retardant ef-fect of the products of thermal transformations of filler components on processes in the condensed and gas phases: the formation of a mechanically strong insulating foam coke layer and the formation of volatile combustion inhibitors.

Reducing the rate of fire spread in buildings through the intersections of enclosing building structures with polymer pipelines is achieved by using fire clutches equipped with liners made of expandable materials. In case of a fire, it is ensured that the spread of flame through polymer pipelines is hindered due to formation of a heat-insulating foamed layer. This layer does not allow the polymer low-melting pipelines to heat up to 120°C. Comparative assessment of heat-insulating and mechanical properties of two intumescent composites and their charred products were carried out to clarify the reasons for their heat-insulating efficiency. Composites included the same intumescent system (ammonium polyphosphate / pentaerythritol / dolomite / thermally expanded graphite) and different polymer binders. The research was conducted using the following methods: complex thermal and X-ray analyses, scanning electron microscopy, a number of standard and original techniques. It was established that heat-insulating ability of a charred layer is determined by temperature intervals in which interactions of initial components occur. The best mechanical, heat-insulating and morphological properties of investigated intumescent composites and their charred layers are achieved when temperature ranges referred to formation of organo-mineral framework and volatile thermolysis products are coinciding. For the composites studied in this paper, this temperature range was 350-400 °C. Thanks to this knowledge, it becomes possible to develop new fire-retardant composites with improved properties instead of selecting the components in empirical way. As a result, the general quality of fire-retardant materials may grow and their properties will be sufficient not only to meet the construction requirements, but to properly operate in case of fire as well, practically justifying the predicted effect.

Introduction. The analysis of flame retardants and extinguishing agents used for preventing and extinguishing fires in an ecosystem is carried out. It is shown that at present there are no weatherproof, environmentally friendly and cost effective extinguishing agents capable of stopping wood and peat burning. Purpose and objectives. Development of cost effective and environmentally friendly synthetic agents capable of both flame retarding and extinguishing natural combustible materials. Materials and methods. Synthetic dispersions of ammonium phosphates of two- and three-valence metals, as well as wood and peat fireproofed by them are the object of the study. Physical and chemical properties of synthesis products in comparison with their fire retarding efficiency are examined. Fireproofing, fire extinguishing, as well as physical and chemical properties of synthesized products are determined using GOST-regulated methods of thermal and chemical analysis, scanning electron microscopy and original methods. Results and discussion. The formulation of Kompleksil synthetic compound effective in extinguishing and fireproofing wood and peat is optimized using a full factorial experiment. At the same time, the inflow of volatile nitrogen containing products into the gaseous phase is identified as the dominating burning inhibition process common for natural combustible materials. The weather resistance (preservation of fireproof properties in respect of forest combustible materials at 79 mm precipitation), forest and environment enhancement (improvement of mineral nutrition conditions and growth of forest plant communities) properties of Kompleksil compound are identified. Conclusions. A cost effective synthetic compound based on natural mineral materials showing fireproofing and extinguishing efficiency when protecting forest combustible materials and peat is developed. This compound was tested in the process of extinguishing real wildfires; its weather resistance is identified, and the positive response of forest plant communities to the application of this multiple action compound is registered. The use of Kompleksil allows to reduce time expenditures and fire extinguishing agent consumption when extinguishing wildfires, which significantly reduces material damage.

14, 220006, Минск, Беларусь Горючесть конструкционных элементов из полимерных материалов в зданиях и сооружениях (трубы, оплетки силовых кабелей) является причиной распространения пожаров, наносящих серьезный экономиче-ский ущерб. Для предотвращения распространения пламенного горения, создания огне-термоизолирующих преград используют противопожарные устройства превентивного действия, ввозимые из-за рубежа, со-держащие вкладыш из термовспенивающегося полимерного композиционного материала. С целью создания отечественного термовспенивающегося материала на основе полиолефинов проведены исследования влия-ния природы и соотношения основных компонентов термовспенивающегося полимерного композиционного материала (полимерного связующего, вспенивающих, каркасообразующих агентов, инертных наполнителей) на физико-химические и огне-термозащитные свойства композитов. Установлено, что состав и содержание полимерного связующего оказывают преимущественное влия-ние на возможность низкотемпературного (120-130 ºС) формования образцов (в виде ленты заданной толщины), эластичность при изгибе, вспенивающую и карбонизующую способности после прогрева. Уста-новлено, что оптимальное содержание полимерного связующего в композиционном материале составляет 40%. Найдено, что коэффициент вспенивания и прочностные свойства (остаточное сжатие) продуктов прогрева термовспенивающегося полимерного композиционного материала зависят, в основном, от содер-жания одного из вспенивающих агентов-терморасширяющегося графита, а также от состава азот-, фосфорсодержащей огнезамедлительной композиции. Определена базовая рецептура термовспениваемого композиционного материала, проявившая удовлетворительные термоизолирующие свойства по результа-там огневых испытаний: смесь этилен-винилацетатного сополимера с бутилкаучуком и хлорпарафином (40%), терморасширяющийся графит (12,5%), силикатный компонент (22,5%) (слюда, волластонит) и смесь вспенивающих и каркасообразующих агентов (25%) (гексаметилентетрамин, доломит, ди-гидрофосфат аммония). Полученные результаты позволяют наметить пути направленного выбора наполнителей и модифицирующих агентов при создании вспениваемых огне-термоизолирующих ма-териалов на основе промышленных термопластов. Ключевые слова: термовспенивающийся композит, терморасширяющийся графит, этилен-винилацетатный сополимер, наполнители, огне-термоизолирующие свойства.

To reduce the economic damage from fires inside buildings and structures that spread along technological structures from polymeric materials (pipes, power cables in polymeric braids), fire and heat-insulating barriers are created. Modern fire protection requirements for communications correspond to fire fighting devices that cut off the spread of flaming combustion along polymer structural elements that permeate multi-storey buildings. Development of an effective low costing termo- foaming polymeric composite material (TPKM) with predetermined properties, research of the dependence of its thermal properties, foaming capacity, fire-termo-protective efficiency, and also physical and mechanical properties of products of its warming up on nature and content of binder and fillers.

The combustibility of polymeric structural elements (pipes, braided power cables) passing through floors and partitions of buildings and constructions causes the spread of fires, which leads to serious economic damage. In order to prevent the spread of fiery burning, to create fire-thermo-insulating barriers fire preventive devices imported from abroad are used. The device contains a liner, which consists of a thermally foamed polymeric composite material. In order to create a domestic fire-thermoprotective expandable composite material based on polyolefins, the influence of the nature and the ratio of the polymer composites main components (polymer binder, foaming, carcass forming agents, inert fillers) on physicochemical and fire-protective properties has been studied. It was established that the nature and content of the polymer binder predominantly affects the possibility of low-temperature (120–130 ºС) molding of samples in the ribbon form of a given thickness, on their elasticity in bending, on a foaming and carbonizing ability after heating. It is established that the optimal content of the polymer binder in the composite material is 40%. It was found that the foaming coefficient and the strength properties (residual compression) of heating products of the composites depend mainly on the content of one of the foaming agents — thermo-expanding graphite, as well as on the nature and content of phosphorus-nitrogen-containing components of the filler. It was determined the basic composition of a thermally expandable polymer material, which showed satisfactory thermal insulation properties according to the results of fire tests: a mixture of ethylene-vinyl acetate copolymer with butyl rubber and chloroparaffin (40%), thermally expanding graphite (12.5%), silicate component (mica, wollastonite — 22.5%), a mixture of foaming and carcass forming agents (hexamethylenetetramine, dolomite, ammonium dihydrophosphate — 25%). The obtained results make it possible to outline the paths of directional choice of fillers and modifying agents in the creation of fire-protectiv and thermo insulating expandable materials based on industrial thermoplastics.

Formation of colloidal particles in tin-containing alcoholic solutions was studied in relation to the SnCl2 concentration, storage time, and kind of the solvent and stabilizing additive. The highest category of flame resistance and the highest resistance of the fireproofing coating to repeated launderings are reached when the poly(ethylene terephthalate) fabric is activated with alcoholic SnCl2 solutions with high concentration of 10–15-nm colloidal particles prior to application of an inorganic fireproofing compound.