Regularities of producing of nano-filled polypropylene microfibers

The research on the influence of the concentration of the combined nano-dispersing additive of titanium oxide / silica (TiO2/SiO2) on the rheological properties and the structure-formation processes in a mixture of polypropylene / co-poliamid (PP/CPA) has been conducted. Established that during the flow of melt the allocation of components on phases with the formation of liquid jets (PP microfiber) in the matrix spa takes place

Thermally and organomodified montmorillonite as effective regulators of the structure formation process in polypropylene/polystyrene blends

The influence of the concentration of thermally and organomodified montmorillonite on the processes of structure formation in a blend of polypropylene/polystyrene (PP/PS) was studied. It is established that in nanofilled compositions, as well as in the original, is formed a microfibrillar structure, the dimensional characteristics of which depend on the content of the additive and the method of its modification. The investigated clays by content (0.2-2.0) wt. % by weight of polypropylene have a compatibilizing effect in the blend of PP/PS, which reduces the average diameter of microfibers by 1.6 times and increases the homogeneity of their distribution by diameter: statistical indicators decrease (standard deviation, variance, coefficient of variation). The modifying effect of thermally modified clay is higher – the improvement of the dimensional characteristics of PP microfibers is achieved at its minimum content in the blend (0.2 wt. %). The formation of anisotropic PP structures in the PS matrix and the relaxation of the accumulated stresses at the exit of the molding hole is the main factor that causes high values of the coefficient of swelling of the extrudates (4.0-7.7). The change in the microstructure of the extrudates of nanofilled systems during spinning depends on the composition of the blend and the method of modification of montmorillonite. The average diameters of microfibers decrease from 2.2 μm (in the original blend) to (1.3-2.0) μm (in threecomponent) depending on the content of additives. The ability to regulate the microstructure of incompatible polymer blends by introducing additives of thermally and organomodified montmorillonite will contribute to the creation of nanocomposites with controlled morphology, as well as new fine-fiber materials with improved filtering characteristics

Life history traits influence in gonad composition of two sympatric species of flatfish

AbstractParalichthys orbignyanus and Paralichthys patagonicus are flatfish with different life history traits, having in common the condition of breeding in seawater. Paralichthys patagonicus remain their whole life in open seawater and Paralichthys orbignyanus are sometimes found in brackish water bodies. As marine and estuarine food webs have different fatty acid (FA) compositions, the aim of this study was to characterize the gonadal maturation of P. orbignyanus and P. patagonicus females through the analysis of lipid content and FA profile in order to understand to what extent life history traits are reflected in the ovarian composition. During gonadal maturation lipid content increased and FA profiles changed in both species, but the lipid increase was greater in P. orbignyanus. The N-3FA and n-3HUFA proportions increased in both species but were higher in P. orbignyanus. The differences between the lifestyles of these species were reflected in the ovarian FA profile mainly as a result of differences in their FA metabolism, causing a greater accumulation of n-3FA and n-3HUFA in P. orbignyanus than in P. patagonicus. The higher lipid accumulation in P. orbignyanus’ ovaries could indicate that this species, feeding in brackish water bodies, has the possibility of storing more energy than P. patagonicus

Stability of common and modified exfoliated graphite to oxidation

Інтеркаляційні сполуки графіту акцепторного типу А-ІСГ можуть бути зазвичай отримані шляхом електрохімічного окислення графіту у водних кислих або нейтральних розчинах. Паралельно з утворенням А-ІСГ на аноді зазвичай має місце виділення кисню. Це може призводити до необоротних змін в матеріалі і, отже, до втрати оборотності в системі, пов'язаної з частковим окисленням графіту. Запропонований спеціальний електрохімічний метод тривалої послідовної циклічної вольтамперометрії для оцінки стійкості графіту до окислення. Оцінені основні механізми корозії для різних типів графітів. Співставленні спеціальні типи розширених графітів, модифікованих P2O5, B2O3 and H3BO3. Найбільший термін служби (до 550 циклів) має розширений графіт, модифікований 5% B2O3.Интеркаляционные соединения графита акцепторного типа А-ИСГ могут быть обычно получены путем электрохимического окисления графита в водных кислых или нейтральных растворах. Параллельно с образованием А-ИСГ на аноде обычно имеет место выделение кислорода. Это может приводить к необратимым изменениям в материале и, следовательно, к потере обратимости в системе, связанной с частичным окислением графита. Предложен специальный электрохимический метод длительной последовательной циклической вольтамперометрии для оценки устойчивости графита к окислению. Оценены основные механизмы коррозии для различных типов графитов. Сопоставлены специальные типы расширенных графитов, модифицированных P2O5, B2O3 and H3BO3. Наибольший срок службы (до 550 циклов) имеет расширенный графит, модифицированный 5 % B2O3.Acceptor-type graphite intercalation compounds (A-GIC) can usually be obtained through electrochemical oxidation of graphite in aqueous acidic or neutral solutions. Oxygen evolution usually takes place at the anode in parallel to the A-GIC formation. It can lead to irreversible changes in the material, and consequently to a loss of reversibility of the system, caused by the partial oxidation of graphite. A special electrochemical method of prolonged sequential cyclic voltammetry was proposed for evaluation of graphite stability to oxidation. The main corrosion mechanisms for different types of graphite are estimated. Special types of TEG modified by P2O5, B2O3 and H3BO3 are compared. A maximal cycling life (up to 550 cycles) is obtained with TEG modified by 5% of B2O3

Модифіковані нанодобавками поліпропіленові тонковолокнисті фільтрувальні матеріали

Properties of fine-fiber filter materials (FM) obtained by extraction of matrix polymer from a microfibrillary composite in the form of a film formed by extrusion of polypropylene (PP) / copolyamide (CPA) / nano-additive mixtures were studied. The main structural unit of FM is polypropylene microfiber (microfibrill), filled with mineral silica-based nano-additives. Modified FMs are characterized by high efficiency of air purification of mechanical particles of 0,3 μm and higher. The possibility to adjust the precision of filters by reducing the diameters of PP fibrils formed in situ and to increase their mass fraction is shown. This was achieved by introducing of nano-additives of different chemical nature into the mixture of PP/CPA and changing their concentration. Nanoparticles in the structure of filter materials contribute to their hydrophilicity and specific surface increasing, and also provide adsorption capacity, and antimicrobial action against a number of microorganisms and fungi.Исследованы свойства тонковолокнистых фильтрующих материалов (ФМ), полученных экстракцией матричного полимера из микрофибриллярного композита в виде пленки, сформированной методом экструзии смесей полипропилен (ПП) / сополиамид (СПА) / нанодобавка. Основной структурной единицей ФМ являются полипропиленовые микроволокна (микрофибриллы), наполненные минеральными нанодобавками на основе кремнезема. Модифицированные ФМ характеризуются высокой эффективностью очистки воздуха от механических частиц размером 0,3 мкм и выше. Показана возможность регулирования прецизионности фильтров за счет уменьшения диаметров, сформированных in situ ПП фибрилл и увеличением их массовой доли. Наночастицы в структуре фильтровальных материалов способствуют повышению их гидрофильности и удельной поверхности, а также обеспечивают адсорбционную способность и антимикробное действие по отношению к ряду микроорганизмов и грибов.Досліджено властивості тонковолокнистих фільтрувальних матеріалів (ФМ), одержаних екстракцією матричного полімеру із мікрофібрилярного композиту у вигляді плівки, сформованої методом екструзії сумішей поліпропілен (ПП) / співполіамід (СПА) / нанодобавка. Основною структурною одиницею ФМ є поліпропіленові мікроволокна (мікрофібрили), наповнені мінеральними нанодобавками на основі кремнезему. Модифіковані ФМ характеризуються високою ефективністю очищення повітря від механічних частинок розміром 0,3 мкм і вище. Показано можливість регулювання прецизійності фільтрів за рахунок зменшення діаметрів, сформованих in situ ПП фібрил та збільшення їх масової долі. Наночастинки у структурі фільтрувальних матеріалів сприяють підвищенню їх гідрофільності і питомої поверхні, а також надають адсорбційну здатність та антимікробну дію до низки мікроорганізмів і грибів

Вплив нанодобавок на формування матрично-фібриллярної структури в розплавах сумішей полімерів та на властивості комплексних ниток

The influence of concentration of additives silver/silica (Ag/SiO2) and silver/alumina (Ag/Al2O3) on the processes of structure-formation in the thermodynamically incompatible mixtures of polypropylene/copolyamide (PP/CPA) and the properties of complex threads from nano-filled PP microfibers were researched. Nano-fillers, that were used, show the compatabilization action in the mixture, reducing the value of interfacial tension and increasing the degree of dispersion and deformation of drops of disperse phase. This leads to a decrease in the average diameter of PP microfibers and reduction of mass fraction of films and particles, which the more perfect matrix-fibrillar structure is forming. The researched silver-containing nano-additives provide to complex threads an antimicrobial properties and improve their mechanical properties

Comparing the Effect of Nanoclays on the Water-resistance of Intumescent Fire-retardant Coatings

This paper reports a study into the effect of nanoclays on the water-resistance of the intumescent system ammonium polyphosphate/melamine/pentaerythritol/titanium dioxide/polymer (ethylene vinyl acetate (EVA) or styrene acrylate (SA). It has been established that adding nanoclay to a coating based on ethylene vinyl acetate increases the fire resistance limit of a metal plate by 30 %, and to a coating based on styrene acrylate – by 50 %. At the same time, coatings that include the EVA polymer are characterized by greater fire-retardant efficiency and less water resistance than coatings containing the SA polymer. It has been shown that intumescent coatings, regardless of the nature of the polymer, under the conditions of 80 % humidity over 800 days their reduce fire-protective properties by an average of 10 %. The loss of coating fire resistance occurs due to the leaching of pentaerythritol, ammonium polyphosphate, and polymer degradation by hydrolysis. The admixtures of nanoclays with a high degree of exfoliation to the studied system create a barrier effect and maximize the chemical formulation of the intumescent coating. The fireproof properties of coatings with organically-modified montmorillonite admixtures are maintained or reduced to 5 % under the conditions of 80 % humidity over 800 days. It has been determined that the direct effect of water on the coating over a period of more than 2 days leads to a significant decrease in the swelling coefficient of intumescent coatings, regardless of the content of a nanoclay admixture in their composition. At the same time, the half-decay period of coatings without nanoclay, calculated on the basis of solubility constant in water, is 0.5 days. For coatings, which include the admixtures of organically-modified nanoclays, the half-decay period increases to 2 days. The results reported in this paper could be recommended for designing water-proof fire-resistant reactive-type nano-coatings with prolonged service life

Comparison of Fire Resistance of Polymers in Intumescent Coatings for Steel Structures

Thermal destruction of fire-retardant intumescent coating of the composition of ammonium polyphosphate (APP)/melamine (MA)/pentaerythrite (PE)/titanium oxide (TiO2)/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/TiO2 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 fir