ELECTROSPINNING OF ANTIBACTERIAL POLYURETHANE/ZnO NANOFIBERS

In this study, it is aimed to produce and characterize antibacterial polyurethane (PU)/Zinc oxide (ZnO) nanofibers by electrospinning method. Firstly, polymer solutions were prepared at various ZnO concentrations such as 0, 0.2, 0.4, 0.6, 0.8, 1. Then solution properties (conductivity, viscosity, surface tension) were determined and analysed the effects of ZnO concentration on the solution properties. PU/ZnO nanofibers produced via electrospinning under the optimum process parameters (voltage, distance between electrodes, feed rate and atmospheric conditions). Finally, the nanofibers were characterized in terms of fibre morphology, thermal stability, permeability and antibacterial activity using SEM-EDS, DSC-TGA, water vapour permeability and disk diffusion methods. According to the solution results; it was observed that conductivity and surface tension decrease significantly with ZnO addition. On the other hand, solution viscosity increases as the ZnO concentration increases. From the SEM images, it has been seen clearly that average fibre diameter increases with ZnO concentration and incorporation of ZnO particles to the fibre structure was verified by SEM-EDS. According to the thermal analyse result, nanofibers begin to degrade between 271.94 ºC and 298.73 ºC. In addition, water vapour permeability increases as the ZnO concentration increase. Lastly antibacterial activity against gram negative (E.coli) and gram positive (S. aureus) was determined with specific zone diameter.

CLOTHES DEVELOPMENT BASED ON METHODS OF HANDLING OF PREMATURE BABIES IN THE INTENSIVE CARE UNIT

The health of children born prematurely remains a significant challenge, but clothing products designed considering medical requirements and handling methods used in the intensive care unit, may contribute to the reduction of neonatal mortality. Assistants in the therapy unit implement practices based on the needs of vulnerable infants, from the very first second of life. This pilot clinical study was conducted in a specialised on neonatal intensive care unit, at the IMSP Municipal Clinical Hospital Gheorghe Paladi from Chisinau. Informed consent of parents and/or careers was required. All users (nurses and doctors) were informed about the product and instructed regarding dressing and undressing process. This controlled study was conducted under the supervision of doctors and nurses. As the study was exploratory in nature, aspects of grounded theory have been used for qualitative data collection. The sample studied consists of preterm infants less than 30 weeks GA, admitted by UTIN in 2018. The population eligible for qualitative data collection was made up of neonatology nurses from the clinic. To obtain a heterogeneous sample, aspects such as age, work experience, environment, and education were considered. The method of observation and subsequent testing used of the newly designed products and every manipulation under medical conditions was intensely studied. Local reactions, if any, due to the texture and quality of the textile material that come into contact with the baby's skin, were also carefully monitored. The process of dressing and stripping off the products, carrying out medical manipulations (in case of neonatal emergencies), were also carefully observed for developing ease of use clothes.

OPTIMIZATION OF SOME WEAVING MACHINE PARTS DESIGN. THEORETICAL APPROACH

The factors of increasing productivity, reducing the cost and the quality improvement are the most important research concerns in weaving machinery. Increasing the effectiveness and productivity of production were achieved by increasing the operating time and efficiency of weaving looms. Thus, the manufacturers of weaving equipment attempt to minimize factors that limit production speed and production conditions. Heald frame is one of the known parts of the weaving machine that causes vibrations and noise which are important factors that influence high-speed development of looms. In this research work, study of mechanical factors (stresses and vibration) has been investigated for heald shaft. Finite element model of the heald frame was constructed to simulate different type of material. Then some important natural frequencies and vibration modes are calculated and the results. Results show a major improvement with the usage of these different material. As well as the failure of heald shaft is mainly due to friction and vibration and not due to the stresses or weight.

ACCESSIBILITY AND USABILITY OF THE LEARNING TOOLS TO ACCELERATE INNOVATION IN THE FIELD OF SMART MATERIALS DEVELOPMENT

This work presents the general aspects concerning the accessibility and usability of the learning tools existent for smart materials development using eco-design in the context of the circular economy. These learning tools will be used in part and some of them developed in the framework of the Erasmus+ project DigiTEX and will cover also the aspects of digital learning technologies capable to accelerate innovation in the field of healthcare and protective systems based on electroconductive materials. In DigiTEX Erasmus+ project will be developed solution-based software technologies, database development and creative methods for coaching the innovative ideas from design, development and production management in the context of circular economy and sustainable development with reduced environmental impact. This paper is structured in 5 sections such as introduction, smart materials overview, eco-design for smart materials, circular economy approach and conclusions.

ELECTROSPINNING OF ST. JOHN'S WORT OIL LOADED MICROCAPSULES BASED PVA NANOFIBERS

In this study, it was achieved that the production of St. John's Wort oil loadad Eudragit RS 100/PVA microcapsules by emulsion/solvent evaporation method and the microcapsules were embedded in PVA nanofibers. Morphological analysis was carried out with SEM images of both microcapsules and nanofibers. The presence of St. John's Wort oil, PVA and Eudragit RS 100 polymers were confirmed in the chemical structure of microcapsules and nanofibers by FT-IR. According to experimental studies, microcapsules were produced to have a smooth surface, a spherical shape and a uniform particle size. The PVA concentration was kept constant at 10% wt and microcapsule concentrations were applied as 1, 3, 5, 7, and 9 wt %. Then, polymer solution properties were measured, such as conductivity, viscosity, and surface tension. It was determined that viscosity and surface tension values increased with microcapsule concentration increase, while conductivity did not change significantly. Nanofiber production was realized via the electrospinning method under the optimum process parameters. According to the SEM images and histogram, nanowebs have a fine fiber diameter, smooth surface, high quality and no bead structure. In addition, the average microcapsule size is 30 μm, average fiber diameter is 430 nm and the fiber diameter uniformity coefficient is 1,014. It is thought that this nanofiber surface containing microcapsules embedded in St. John's Wort has the potential to be used as a wound dressing.

ACTIVE PRINCIPLES APPLIED ON BIOMATERIALS FOR THE CURATIVE THERAPY OF INFLAMMATORY SKIN DISEASES - A REVIEW

Every year, millions of peoples are affected by skin injuries of either an acute or chronic nature. Worldwide 300,000 people die every year in lower-middle-income countries due to chronic wounds and burn injuries. Wounds are described as the disruption in the skin integrity and function, which arises from different causes such as trauma, surgery, diabetes, and burns. Skin provides a mechanical barrier against the external environment and has further roles in thermoregulation, metabolism and regulation of fluid balance. Skin diseases can affect each of these regions and they can be influenced by body size, sex, age, medications, diet, and microenvironment. Also, they can manifest whether the skin is healthy or diseased. Wound dressings are critical to wound care, providing a physical barrier between the wound and the external environment to prevent further damage or infection. The most promising wound dressings are biocompatible, enable physical protection of the wound milieu against penetration of bacteria and are highly porous. The use of natural biocompatible drugs is highly desirable in wound dressing compared to synthetic chemicals. To achieve an adequate therapeutic effect, different polymeric systems are used for drug delivery. To improve drug efficacy, safety, patient compliance and convenience a drug delivery system is modified to enhance drug release profile, absorption, distribution and elimination of the drug. The present review is an attempt to brief readers about the engineering of wound dressing materials from natural and synthetic sources upfront using active principles, such as bee products, drugs, essential oils, metallic nanoparticles and vitamins.

OVERVIEW OF THE KNITTED MATERIALS WITH VIBRATIONS DAMPING CAPACITY

Textile materials are often subjected to different stresses, acting on them in two phases: during the knitting phase, when the yarns and the obtained structure are subjected to cyclic stress, but also during the use phase, when the knitted structures are subjected to various stresses. The dynamic behaviour of knitted fabrics in a vibrating environment is usually evaluated by standardized methods, such as the method using vibration exciters (e.g., ISO 10819:2013). However, in recent years, the authors' collective has carried out research to characterize the behaviour of knitted structures in a vibrating environment, using a well-known method for generating vibrations by impact excitation, which is specific to the mechanical field but also has a high potential for application in the textile field. This method refers to the determination of the free vibrations of an elastic system. Its measurement in the design phase of the system is considered a crucial step, since by knowing the frequency range of the system, the resonance phenomenon in the operational phase can be avoided. Similar results obtained by applying standardized methods for measuring vibration transmissibility and the currently adapted method from the field of mechanics to the field of textiles, represent a validation for this type of investigation process and also show the high potential of knitwear to be used in the vibration environment.

INTEGRATION OF MAGNETIC MATERIALS WITH ACTUATOR ROLE ON TEXTILE SUPPORTS

Magnetic textile materials represent a new category of smart materials, whose properties are obtained either by adding magnetic materials during the technological processes of obtaining fibres and yarns, either by applying some magnetic materials on textile surfaces during the chemical finishing processes (electroless plating, electroplating, magnetron sputtering). Therefore, by adding magnetic nano powders in the spinning solution, fibres with magnetic properties are obtained, by adding metallic fibres, with magnetic properties, during the spinning process, magnetic yarns are obtained, and by the insertion of a certain percent of metallic/magnetic yarns during the weaving or knitting process, textile materials with magnetic properties are obtained. Thus, magnetic textile materials will possess the uniqueness of a textile structure due to specific features as flexibility, breathability or lightweight, but at the same time, also the magnetic properties necessary in multiple applications such as magnetic sensors, actuators and electromagnetic shielding used in technical applications for defence, automotive and aerospace.

TWO-STEP CROSSLINKING OF PVP/GEL NANOFIBERS

In this study, it was achieved that crosslinking of PVP/GEL nanofibers with two-steps. Crosslinking is a process highly important for water-soluble polymers in terms of application areas and mechanical properties. Firstly, crosslinking of PVP polymers experimental studies were carried out via heat treatment at different temperatures and times. Then, GEL polymers were crosslinked with GTA vapour at different times. Morphological analysis was carried out via SEM images and chemical characteristics were determined via FT-IR analysis. Moreover, after the crosslinking process, SD and WL values were calculated. All results showed that before crosslinking of SEM images, nanofibers were smooth, fine and without beads. The average fiber diameter is 196 nm and the fiber diameter distribution is quite uniform. After crosslinking of SEM images, it is expected that all nanowebs will turn from fibrous surfaces to membranous. Generally, SD and WL values decrease with crosslinking time increase. According to all of the SEM images, SD and WL values, optimum conditions were determined for PVP as 4 hours at 180oC and for GEL as 24 hours. Lastly, the presence of PVP and GEL polymers in the nanofiber structure was verified chemically with FT-IR analysis.

CARBON FIBRE ALIGNMENT FOR REINFORCED COMPOSITES USING EMBROIDERY TECHNOLOGY

Composites are materials formed by the combination of two or more components that acquire better properties than the ones obtained by each component on its own. Composites have been widely used in the industry due to its light weight and good mechanical properties. To improve these properties several layers of reinforced material (e.g., carbon fibre) are overlapped which produce an increase in the fibre consumption. In this sense Tailored Fibre Placement (TFP) embroidery can offer good opportunity to reduce the consumption of reinforced fibre while improving the mechanical properties due to the alignment of the fibres in the effort direction. This study analyzes the performance of carbon fibre reinforced composites with Polyester resin made with TFP embroidery technology against flexural strength efforts and without using plain woven fabrics to demonstrate that the use of reinforcement fabrics in composites can be optimized by a curved alignment of the fibers. Two different structures were embroidered with TFP technology, one simulating a woven fabric with straight unidirectional alignment of fibres in horizontal and vertical direction, and a second structure made with curvilinear alignment of carbon fibers. After the study of the flexural mechanical properties an improvement of 18% was obtained in maximum flexural strength.