Wet spinning of strong cellulosic fibres with incorporation of phase change material capsules stabilized by cellulose nanocrystals

Incorporating a phase change material (PCM) into fibres allows the fabrication of smart textiles with thermo-regulating properties. Previously, such fibres have been made from thermoplastic polymers, usually petroleum-based and non-biodegradable, or from regenerated cellulose, such as viscose. Herein, strong fibres are developed from aqueous dispersions of nano-cellulose and dispersed microspheres with phase changing characteristics using a wet spinning technique employing a pH shift approach. Good distribution of the microspheres and proper compatibility with the cellulosic matrix was demonstrated by formulating the wax as a Pickering emulsion using cellulose nanocrystals (CNC) as stabilizing particles. The wax was subsequently incorporated into a dispersion of cellulose nanofibrils, the latter being responsible for the mechanical strength of the spun fibres. It was possible to produce fibres highly loaded with the microspheres (40 wt%) with a tenacity of 13 cN tex−1 (135 MPa). The fibres possessed good thermo-regulating features by absorbing and releasing heat without undergoing structural changes, while maintaining the PCM domain sizes intact. Finally, good washing fastness and PCM leak resistance were demonstrated, making the fibres suitable for thermo-regulative applications. Continuous fabrication of bio-based fibres with entrapped PCMs may find applications as reinforcements in composites or hybrid filaments

Nanofibres de cellulose pour la production de bionanocomposites

One of the main challenges in the context of biocomposites development is to replace petroleum-based materials with bio-based. Because of their natural origin, relatively high strength and the ability to form transparent products, cellulose nanofibers have a large potential for application in the composite materials. This work was focused primarily on the optimization of cellulose nanofiber production methods using biochemical and mechanical treatments, secondly on their rheological and structural properties in an aqueous medium and thirdly on the production of latex-based composites. The questions of homogeneous dispersion of cellulose nanofibers in the matrix and the interactions between these components for the purpose of matrix reinforcement are particularly addressed.Un des principaux challenges dans le contexte du développement des matériaux biocomposites est de remplacer les matières plastiques à base de pétrole par des matériaux biosourcés. En raison de leurs origines naturelles, d'une résistance relativement élevée et de leur capacité à former des produits transparents, les nanofibres de cellulose possèdent un grand potentiel d'applications dans les matériaux composites. Dans ce travail des résultats ont été apportés premièrement sur l'optimisation des procédés de productions de nanofibres de cellulose par des traitements biochimiques et mécaniques, deuxièmement sur leurs propriétés rhéologiques et structurelles en milieu aqueux et troisièmement sur la production de composites à matrice de latex. Les questions de dispersions homogènes de nanofibres de cellulose dans la matrice et des interactions entre ces composants à des fins de renforcement des bio-composites ont été étudiés en détails

Nanofibres de cellulose pour la production de bionanocomposites

One of the main challenges in the context of biocomposites development is to replace petroleum-based materials with bio-based. Because of their natural origin, relatively high strength and the ability to form transparent products, cellulose nanofibers have a large potential for application in the composite materials. This work was focused primarily on the optimization of cellulose nanofiber production methods using biochemical and mechanical treatments, secondly on their rheological and structural properties in an aqueous medium and thirdly on the production of latex-based composites. The questions of homogeneous dispersion of cellulose nanofibers in the matrix and the interactions between these components for the purpose of matrix reinforcement are particularly addressed.Un des principaux challenges dans le contexte du développement des matériaux biocomposites est de remplacer les matières plastiques à base de pétrole par des matériaux biosourcés. En raison de leurs origines naturelles, d'une résistance relativement élevée et de leur capacité à former des produits transparents, les nanofibres de cellulose possèdent un grand potentiel d'applications dans les matériaux composites. Dans ce travail des résultats ont été apportés premièrement sur l'optimisation des procédés de productions de nanofibres de cellulose par des traitements biochimiques et mécaniques, deuxièmement sur leurs propriétés rhéologiques et structurelles en milieu aqueux et troisièmement sur la production de composites à matrice de latex. Les questions de dispersions homogènes de nanofibres de cellulose dans la matrice et des interactions entre ces composants à des fins de renforcement des bio-composites ont été étudiés en détails

Self-Standing, Robust Membranes Made of Cellulose Nanocrystals (CNCs) and a Protic Ionic Liquid: Toward Sustainable Electrolytes for Fuel Cells

Energy-conversion devices based on the phenomenon of proton conduction, for example, polymer electrolyte membrane fuel cells (PEMFCs), require low cost and sustainable electrolytes with high ionic conductivity and good mechanical properties under anhydrous conditions and at temperatures up to 150 \ub0C. Biopolymers possess an intrinsic thermomechanical stability but an insufficient proton conductivity in the dry state, which however may be imparted by a protic ionic liquid (PIL). This work presents the preparation and properties of composite membranes made of cellulose nanocrystals (CNCs) and a PIL. The membranes are thermally stable and display an ionic conductivity within the range 10-4-10-3 S/cm for temperatures between 120 and 160 \ub0C. Moreover, the analysis of the biopolymer\u27s apparent dimensions at nanoscale reveals a dependence of the CNCs\u27 defects, twisting, and aggregation in the presence of the PIL. Preliminary tests using a simple fuel cell setup demonstrate a response of the membranes to the inlet of H2 gas, with a generation of electrical current. These findings provide a solid groundwork for further development and future studies of biopolymer/PIL electrolytes for energy applications

Технологические особенности и систематизация способов термотрансферной печати

Проаналізовано технологічні особливості термотрансферного друку, розглянуто застарілі і сучасні способи друку, узагальнено і систематизовано їх різновиди, виділено основні складові технологічних процесів, характеристик матеріалів і устаткування.The technological features of heat transfer printing are analysed, the out-of-date and modern methods of printing are considered, generalized and systematized their variety, the basic components of technological processes, descriptions of materials and equipment are singled out.Проанализированы технологические особенности термотрансферной печати, рассмотрены устаревшие и современные способы печати, обобщены и систематизированы их разновидности, выделены основные составляющие технологических процессов, характеристик материалов и оборудования

Сучасні методи підсилення фундаментів мілкого закладання середньої загальноосвітньої школи

Робота публікується згідно наказу ректора від 29.12.2020 р. №580/од "Про розміщення кваліфікаційних робіт вищої освіти в репозитарії НАУ". Науковий керівник: Білокуров Павло Сергійович, к.т.н., доцент кафедриThe problem of foundation strengthening in the reconstruction of houses is especially relevant in large cities. The main reason is commercial the attractiveness of buying houses in the central part of the city and superstructure of additional floors. As a result, increase load on the foundation.The main reasons for the need of foundation strengthening are an increase in the load when adding buildings or change of their functional purpose, disturbances in coupling of masonry materials, the destruction of the foundation material from the action of aggressive environments, deformations due to loss of strength or sedimentation of the bases. Depending on the design of the foundations, as well as the nature of deformations and the reasons, their daring, various ways of repair and strengthening are applied deformed foundations.The issue of reconstruction is very relevant today. Exactly reconstruction of already operated industrial and residential buildings is one of the primary problems of modern builders.Проблема зміцнення фундаменту при реконструкції будинків особливо актуальна у великих містах. Основна причина - комерційна привабливість покупки будинків у центральній частині міста та надбудова додаткових поверхів. Як результат, збільшити навантаження на фундамент. Основними причинами необхідності зміцнення фундаменту є збільшення навантаження при додаванні будівель або зміна їх функціонального призначення, порушення зчеплення кладочних матеріалів, руйнування матеріалу фундаменту від дії агресивного середовища, деформації внаслідок втрати міцність або осідання основ. Залежно від конструкції фундаментів, а також характеру деформацій та причин, їх сміливості застосовуються різні способи ремонту та зміцнення деформованих фундаментів. Питання реконструкції дуже актуальне сьогодні. Точно так реконструкція вже діючих промислових та житлових будівлі - одна з головних проблем сучасних будівельників

Accelerated ageing of cotton canvas as a model for further consolidation practices

In order to assess the effectiveness of various practices for canvas consolidation, model substrates areneeded. In this work, a method of rapid ageing of cotton canvas is described. The method consists oftreatment of the canvas with a mixture of hydrogen peroxide and sulfuric acid at 40◦C during 72 hoursto mimic to some extent the natural processes of oxidation and acid-catalysed hydrolysis of cellulose.Two protocols for canvas degradation were developed, which reduced the degree of polymerization ofcellulose from ca. 6250 to ca. 1350 and 450. The reduction of the mechanical properties and the increaseof the negative charge were also quantified. These samples were compared with a canvas degraded usinga state-of-the-art method that takes up to 20 days. The results show that the developed method canprovide a rapid procedure for preparing small samples for testing various consolidation strategies byconservators

Управление курсором при помощи зрительного тракта

Розглядається метод керування курсором за допомогою зорового тракту з використанням веб- камери. Розроблено програмний комплекс для відслідковування погляду користувача та переміщення курсору в зону погляду. В основі лежить метод, отриманий інтегруванням методу каскадів Хаара та модифікованого методу темплейтів. Даний метод дозволяє швидко і точно знайти положення очей та перемістити курсор. Також, на відміну від методу, використаного в ПЗ “Cameramouse”, даний метод автоматично знаходить область з очима.Viewed method for controlling the computer cursor by the visual system of the human with using webcam. A programmatic complex is developed for watching of look of user and cursor update in the area of look. A method, got integration of method of cascades of Khaar and modified method of templeytov, lies in basis. Unlike a method, utillized in “Cameramouse”, allows automatically to find an area with eyes.Рассматривается метод управления курсором при помощи зрительного тракта с использованием веб-камеры. Разработан программный комплекс для отслеживания взгляда пользователя и перемещения курсора в область взгляда. В основе лежит метод, полученный интегрированием метода каскадов Хаара и модифицированного метода темплейтов. В отличие от метода, использованного в ПО “Cameramouse”, позволяет автоматически находить область с глазами

Systematic mechanical assessment of consolidants for canvas reinforcement under controlled environment

In conservation, adhesives are commonly used for the consolidation of canvases, yet their impact upon the canvas longevity has raised some concerns amongst conservators. As such, this study presents a testing protocol developed to assess the performance of commonly-used adhesives (natural animal glue and synthetic Beva® 371) and a newly developed nanocellulose consolidant, nanofibrillated nanocellulose (CNF). This includes their effect on the visual appearance, consolidation, and response of the mechanical properties of the treated canvases to programmed changes in relative humidity (RH). Scanning electron microscopy (SEM) images of animal glue- and Beva® 371-treated canvases revealed the presence of adhesive and consolidant on and in-between cotton fibres. The consolidants form bridges linking and connecting the cotton fibres and holding them together, whereas the CNF treatment, formed a visible continuous and dense surface coating. None of the treatments induced any discernible colour change. Controlled environment mechanical testing was performed in two ways: by applying a linearly increasing static force at fixed RH (Young’s modulus) and by applying a dynamic force together with a programmed RH cycling between 20 and 80% (RH dependent viscoelastic properties). CNF gave a higher value of Young’s modulus than either of the two commonly-used materials. Measurements at different values of RH (20 and 80%) demonstrated for all the treated canvases that at the lower value (RH 20%) Young’s modulus values were higher than at the higher value (RH 80%). Besides, the dynamic mode showed that the rate of response in all cases was rapid and reversible and that the nanofibrillated cellulose treated sample showed the highest variation in storage (or elastic) modulus measured at the end of RH plateaux (20 and 80% RH). Thus CNF appears to be a promising material given its higher mechanical performance. The protocol developed in this study has enabled us to examine and compare candidate materials for the consolidation of canvases systematically, using testing parameters that remained relevant to the field of canvas conservation

On the potential of using Nanocellulose for consolidation of painting canvases

Nanocellulose has been recently proposed as a novel consolidant for historical papers. Its use for painting canvas consolidation, however, remains unexplored. Here, we show for the first time how different nanocelluloses, namely mechanically isolated cellulose nanofibrils (CNF), carboxymethylated cellulose nanofibrils (CCNF) and cellulose nanocrystals (CNC), act as a bio-based alternative to synthetic resins and other conventional canvas consolidants. Importantly, we demonstrate that compared to some traditional consolidants, all tested nanocelluloses provided reinforcement in the adequate elongation regime. CCNF showed the best consolidation per added weight; however, it had to be handled at very low solids content compared to other nanocelluloses, exposing canvases to larger water volumes. CNC reinforced the least per added weight but could be used in more concentrated suspensions, giving the strongest consolidation after an equivalent number of coatings. CNF performed between CNC and CCNF. All nanocelluloses showed better consolidation than lining with synthetic adhesive (Beva 371) and linen canvas in the elongation region of interest