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Wyniki wyszukiwania dla: tensile test
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Poly(ε-Caprolactone)/Poly(Lactic Acid) Blends Compatibilized by Peroxide Initiators: Comparison of Two Strategies
PublikacjaPoly(ε-caprolactone) (PCL) and poly(lactic acid) (PLA) blends were compatibilized by reactive blending and by copolymers formed during reaction in the solution. The reactive blending of PCL/PLA was performed using di-(2-tert-butyl-peroxyisopropyl)benzene (BIB) or dicumyl peroxide (DCP) as radical initiator. PCL-g-PLA copolymers were prepared using 1.0 wt. % of DCP or BIB via reaction in solution, which was investigated through...
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A Proposed Soft Computing Model for Ultimate Strength Estimation of FRP-Confined Concrete Cylinders
PublikacjaIn this paper, the feed-forward backpropagation neural network (FFBPNN) is used to propose a new formulation for predicting the compressive strength of fiber-reinforced polymer (FRP)-confined concrete cylinders. A set of experimental data has been considered in the analysis. The data include information about the dimensions of the concrete cylinders (diameter, length) and the total thickness of FRP layers, unconfined ultimate concrete...
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One More Step Towards a Circular Economy for Thermal Insulation Materials—Development of Composites Highly Filled with Waste Polyurethane (PU) Foam for Potential Use in the Building Industry
PublikacjaThe rapid development of the building sector has created increased demand for novel materials and technologies, while on the other hand resulting in the generation of a severe amount of waste materials. Among these are polyurethane (PU) foams, which are commonly applied as thermal insulation materials. Their management is a serious industrial problem, due to, for example, their complex chemical composition. Although some chemical...
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Temperature Evolution, Material Flow, and Resulting Mechanical Properties as a Function of Tool Geometry during Friction Stir Welding of AA6082
PublikacjaThe friction stir welding process was simulated for joining AA6082 aluminum alloy with the use of the computational fluid dynamics method. Two different tool geometries were used—a tapered cylindrical pin (simple pin) and a hexagonal pin with grooves (complex pin). The analysis of the simulations performed was discussed in terms of temperature evolution during the process, total heat input, residual stresses and material flow....
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Effect of wet Hydrogen Sulfide on Carbon Steels Degradation in Refinery Based on Case Study
PublikacjaMaterial degradation caused by wet hydrogen sulfide (Wet H2S) is one of the major issues in refineries. Carbon steel is the main construction material used in refineries and is subjected not only to thickness loss but the hydrogen is the major concern. H2S leads to high atomic hydrogen penetration in steel which causes degradation in the form of blistering and/or cracking (HIC/SOHIC) and stress cracking in the area of welds and...
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Fabrication of the cross-linked PVA/TiO2/C nanocomposite membrane for alkaline direct methanol fuel cells
PublikacjaA crosslinked Poly(vinyl alcohol) based composite membrane was developed through a phase inversion process for use in alkaline direct methanol fuel cells (ADMFCs). The titanium dioxide (TiO2) and carbon nanoparticles (NPs) have been incorporated into the PVA polymer matrix to improve the mechanical and thermal properties. The membrane samples were further modified with maleic acid, a carboxylic acid acting as the cross-linker,...
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Data-Driven Modeling of Mechanical Properties of Fiber-Reinforced Concrete: A Critical Review
PublikacjaFiber-reinforced concrete (FRC) is extensively used in diverse structural engineering applications, and its mechanical properties are crucial for designing and evaluating its performance. The compressive, flexural, splitting tensile, and shear strengths of FRCs are among the most important attributes, which have been discussed more extensively than other properties. The accurate prediction of these properties, which are required...
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Dissimilar autogenous TIG joint of Alloy 617 and AISI 304H steel for AUSC application
PublikacjaTo reduce costs and improve high-temperature performance in Advanced Ultra Super Critical (AUSC) boilers, it is necessary to weld austenitic steel to Inconel alloy. In this study, the autogenous tungsten inert gas (TIG) welding process was used to join Alloy 617 and an austenitic AISI 304H steel plate of thickness 5 mm. Microstructural analysis showed that the microstructure formation was uneven along the weldments, with columnar...
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A study on fibre-reinforced concrete elements properties based on the case of habitat modules in the underwater sills
PublikacjaHydrotechnical constructions are mostly objects functioning in extreme conditions and requiring a custom-made construction project. In the case of using prefabricated elements, it is required to develop production, transport, assembly, conservation and repair technology. Concerning the problem of concrete cracks, modern repair systems allow positive effects to be achieved in many cases of concrete elements repair. In this work...
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Comprehensive Investigation of Stoichiometry–Structure–Performance Relationships in Flexible Polyurethane Foams
PublikacjaPolyurethane (PU) foams are versatile materials with a broad application range. Their performance is driven by the stoichiometry of polymerization reaction, which has been investigated in several works. However, the analysis was often limited only to selected properties and compared samples differing in apparent density, significantly influencing their performance. In the bigger picture, there is still a lack of comprehensive studies...
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Waste tire rubber devulcanization technologies: State-of-the-art, limitations and future perspectives
PublikacjaWaste tires management is a serious and global environmental problem. Therefore, searching for low-cost and industrial-scale applicable tire recycling methods is gaining more and more attention. Waste tire rubber is valuable source of secondary raw materials for the circular economy and current trends indicate that application of waste rubbers during manufacturing value-added products should increase in near future. Sustainable...
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Analysis of Residual Stresses and Dislocation Density of AA6082 Butt Welds Produced by Friction Sir Welding
PublikacjaThe Friction Stir Welding (FSW) method was employed to join AA6082 sheets. The welds were produced with different tool traverse speed (200 and 250 mm/min), rotational speed (1000 and 1250 RPM) and tool tilt angle (0 and 2 deg). Based on the analysis of XRD patterns, the total precipitation volume fractions in the nugget zones and the base material were calculated. The FSW process resulted in a reduction in the fraction of precipitates...
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Mechanical Properties and Residual Stress Measurements of Grade IV Titanium and Ti-6Al-4V and Ti-13Nb-13Zr Titanium Alloys after Laser Treatment
PublikacjaNowadays, surface engineering focuses on research into materials for medical applications. Titanium and its alloys are prominent, especially Ti-6Al-4V and Ti-13Nb-13Zr. Samples made of pure grade IV titanium and the titanium alloys Ti-6Al-4V and Ti-13Nb-13Zr were modified via laser treatment with laser beam frequency f = 25 Hz and laser beam power P = 1000 W during a laser pulse with duration t = 1 ms. Subsequently, to analyze...
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Starch-clay nanocomposite films
PublikacjaStarch is a natural polymer which, due to its renewability, biodegrability, availability and a relatively low cost, has a high potential for applications in biodegradable materials. However, because of its hydrophilic nature, the number of commercially available starch-based products is still limited. Recently, starch-based nanocomposites with the addition of clay minerals as nanofillers have given rise to large-scale improvements...
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Processing and structure–property relationships of natural rubber/wheat bran biocomposites
PublikacjaIn this work, wheat bran was used as cellulosic filler in biocomposites based on natural rubber. The impact of wheat bran content [ranging from 10 to 50 parts per hundred rubber (phr)] on processing, structure, dynamic mechanical properties, thermal properties, physico-mechanical properties and morphology of resulting biocomposites was investigated. For better characterization of interfacial interactions between natural rubber...
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Processing, mechanical and thermal behavior assessments of polycaprolactone/agricultural wastes biocomposites
PublikacjaIn this paper, brewer’s spent grain (BSG) was applied as potential lignocellulose biofiller in biocompos-ites based on polycaprolactone (PCL). The PCL/BSG biocomposites filled with varying content of biofillerswere prepared via low-temperature melt-compounding. These conditions allow limiting thermal degra-dation of used biofillers during processing. The influence of biofiller content (ranging from 25 to 200parts by weight on 100...
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Investigating the Impact of Curing System on Structure-Property Relationship of Natural Rubber Modified with Brewery By-Product and Ground Tire Rubber
PublikacjaThe application of wastes as a filler/reinforcement phase in polymers is a new strategy to modify the performance properties and reduce the price of biocomposites. The use of these fillers, coming from agricultural waste (cellulose/lignocellulose-based fillers) and waste rubbers, constitutes a method for the management of post-consumer waste. In this paper, highly-filled biocomposites based on natural rubber (NR) and ground tire...
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Chitosan-Based Membranes as Gentamicin Carriers for Biomedical Applications — Influence of Chitosan Molecular Weight
PublikacjaOver the past decade, much attention has been paid to chitosan as a potential drug carrier because of its non-toxicity, biocompatibility, biodegradability and antibacterial properties. The effect of various chitosan characteristics on its ability to carry different antibiotics is discussed in the literature. In this work, we evaluated the influence of the different molecular weights of this polymer on its potential as an antibacterial...
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Mechanical and radiation shielding properties of concrete reinforced with boron--basalt fibers using Digital Image Correlation and X--ray micro--computed tomography
PublikacjaThe paper presents experimental investigations of the radiation shielding, mechanical and fracture properties of concrete reinforced with 5 kg/m3 of novel basalt fibers infused with boron oxide (BBF). However, further studies concerning other dosages i.e. 1 kg/m3, 10 kg/m3, 15 kg/m3 and 20 kg/m3 are currently carried out. Experiments with neutron source revealed that addition of BBF as a dispersed concrete reinforcement could improve...
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A facile structural manipulation strategy to prepare ultra-strong, super-tough, and thermally stable polylactide/nucleating agent composites
PublikacjaPolylactide (PLA) is a biodegradable thermoplastic widely used in diferent felds, but it should be adequately modifed considering high-performance applications. However, the current processes for developing PLA materials achieve high strength at the expense of toughness or ductility of the materials. Therefore, there is need to develop new strategies for generation of PLA materials with high strength, great toughness, good ductility,...
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Bioactive polyurethanes applied as a surgical implants
PublikacjaSynthetic materials are applied in many branches of the industry, i.a. in medicine as a casing of apparatus, elements of artificial organs (hearts, blood vessels), catheters, wound healings, intra aortic balloons, mammary implants to mention but a few. Polymeric material used in such applications must be distinguished by a good biocompatybility. Since many years extensive research are employed to develop a new polymers that can...
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Design and material selection for a patient transport device in field hospitals
PublikacjaACKGROUND: A major cause of patient and hospital worker injuries occurs transferring patients between two planes. The main aim of this paper was to propose a design of patient’s lift and transfer apparatus for use in field hospitals. The assumption was to design lightweight, durable and ergonomic device using innovative material. The authors concentrated on partial elimination of manual lifting in order to device could work both...
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Development of nanoscale morphology and role of viscoelastic phase separation on the properties of epoxy/recycled polyurethane blends
PublikacjaA novel and cost-effective approach towards the modification of epoxy matrix has been developed using recycled polyurethane for the first time without sacrificing any of the intrinsic properties of the resin. Polyurethane, recycled from waste foam by glycolysis process (RPU), was found to be very effective in improving the properties of the thermosetting resin based on Diglycidyl ether of bisphenol-A (DGEBA). The effect of the...
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Tensile and Fatigue Behavior of Additive Manufactured Polylactide
PublikacjaThis article presents the results of monotonic tensile and fatigue tests conducted on commercial polylactide or polylactic acid (PLA). The results of fatigue tests for this material present in the literature are limited, especially for additive manufactured elements. The specimens were manufactured using the injection molding and the fused filament fabrication (FFF) method. The FFF specimens were divided into five subgroups, depending...
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Eco-friendly Route for Thermoplastic Polyurethane Elastomers with Bio-based Hard Segments Composed of Bio-glycol and Mixtures of Aromatic–Aliphatic and Aliphatic–Aliphatic Diisocyanate
PublikacjaApplication of bio-based diisocyanates with low volatility instead petrochemical diisocyanates has positive impact on environment by reduction of hazardous effects on living organisms and lead to bio-based polyurethanes (bio-PUs) with good usage properties. This work was focused on the synthesis and chosen properties examination of partially bio-based thermoplastic polyurethane elastomers (bio-PUs) obtained using diisocyanate mixtures,...
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Synthesis, structure and properties of novel poly(hydroxyurethane)s obtained by non-isocyanate route
PublikacjaNon-isocyanate polyurethanes (NIPUs) can be synthesized by polyaddition of five-membered bis(cyclic carbonate)s and primary diamines. NIPUs are an alternative for the commonly used (in the form of foams, elastomers, coatings or fibers) in the industry polyurethanes obtained using toxic and moisture sensitive diisocyanates, polyols and low-molecular weight chain extenders. The main aim of this work was to synthesize non-isocyanate...
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Prediction of maximum tensile stress in plain-weave composite laminates with interacting holes via stacked machine learning algorithms: A comparative study
PublikacjaPlain weave composite is a long-lasting type of fabric composite that is stable enough when being handled. Open-hole composites have been widely used in industry, though they have weak structural performance and complex design processes. An extensive number of material/geometry parameters have been utilized for designing these composites, thereby an efficient computational tool is essential for that purpose. Different Machine Learning...
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The impact of filler thermomechanical modifications on static and dynamic mechanical performance of flexible foamed polyurethane/ground tire rubber/zinc borate composites
PublikacjaThe rapid development of the automotive industry is very beneficial to many aspects of human life, but it is also a very significant environmental burden. The most straightforward impact is related to the generation of exhaust, but the management of post-consumer car parts is also a major challenge. Among them, waste tires are very burdensome due to their enormous numbers. Therefore, it is essential to develop novel, environmentally...
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Micro-cracking pattern recognition of hybrid CNTs/GNPs cement pastes under three-point bending loading using acoustic emission technique
PublikacjaThe generation of microcracks has an important influence on the behaviour of concrete structures. In this study, the acoustic emission (AE) technique was used to investigate the fracture phenomena and micro-cracking behavior of hybrid carbon nanotubes (CNTs, the 1-D allotrope of carbon atoms) and graphene nanoplatelets (GNPs, 2D monolayer of sp2-hybridized carbon atoms), cement composites under three-point bending loading. In...
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Microcracking monitoring and damage detection of graphene nanoplatelets-cement composites based on acoustic emission technology
PublikacjaThis study aims to identify the micro-cracking pattern and structural applications of cement composites replaced with 0 wt%, 0.04 wt%, and 0.08 wt% contents of graphene nanoplatelets (GNPs) over cement weight through acoustic emission (AE) monitoring under mechanical degradation. The ultraviolet-visible spectroscopy (UV–vis) results showed that at 60 min sonication period, GNP-4 showed maximum absorbance rate of 16.15% compared...
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Structure-Property Relationship and Multiple Processing Studies of Novel Bio-Based Thermoplastic Polyurethane Elastomers
PublikacjaCurrently, the growing demand for polymeric materials has led to an increased need to develop effective recycling methods. This study focuses on the multiple processing of bio-based thermoplastic polyurethane elastomers (bio-TPUs) as a sustainable approach for polymeric waste management through mechanical recycling. The main objective is to investigate the influence of two reprocessing cycles on selected properties of bio-TPUs....
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The Influence of Cement Type on Early Properties of Cold In-Place Recycled Mixtures
PublikacjaCold in-place recycling is a commonly used maintenance treatment in rehabilitation of low and medium volume roads in Poland. Typically, two types of binding agents are used—cement and bituminous emulsion (or foamed bitumen).Due to the harsh Polish climate with many freeze/thaw cycles and frequent occurrence of saturated conditions, the used amounts of cement are higher than those commonly used in warmer parts of Europe. While there...
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Recycled rubber wastes-based polymer composites with flame retardancy and electrical conductivity: Rational design, modeling and optimization
PublikacjaPolymer recycling techniques experience a maturity period of design and application. Rubbers comprise a high proportion of polymer wastes, highly flammable and impossible to re-melt. Polymer composites based on ground tire rubber (GTR) and ethylene-vinyl acetate copolymer (EVA) containing carbon black (CB) (1–50 phr), with variable EVA/GTR weight composition (10/90, 25/75, 50/50, 75/25 and 90/10), and processing temperature (Low:...
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Rubber wastes recycling for developing advanced polymer composites: A warm handshake with sustainability
PublikacjaRecycling and management of rubber wastes experiences an early-stage maturity in the quest for sustainable and circular materials. Up to now, solutions proposed for sustainable development of rubber wastes are limited, so that properties and performance features of recycled products are inadequate for practical applications. Herein, an experimental protocol is introduced for manufacturing semi-sustainable polymer composites based...
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Graphene-based Silicone rubber Nanocomposites: Preparation, Characterization, and Properties
PublikacjaThis study aims to understand better the mechanical, thermal, and tribological behavior of silicone rubber nanocomposites. Graphite, exfoliated graphite, reduced graphene oxide, ionic liquid modified graphene oxide, silane-modified graphene oxide, fumed silica, and other fillers were used in this study. Adding graphene-based fillers to the silicone rubber matrix substantially improves the nanocomposite's mechanical, thermal, and...
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Kinga Dawidowska
Osoby