Graphenemex invited by WDT, a leader in nanotechnology and sponsor of the event, to the FMSE International Congress at the American University of Sharjah.
Dr. Ali Alnaser leads the organizing committee with the goal of facilitating knowledge exchange between government, scientific and industrial leaders from around the world.
Part II
In the previous article on Textile Innovations, we explored the trends of graphene in the industry, focusing on its practical applications in textiles, leveraging its electrical, thermal, fire resistance, and mechanical properties. In this article, we will delve into the advantages of graphene, considering its multifunctional benefits such as its barrier effect with a focus on waterproofing and antimicrobial properties, as well as its contributions to UV protection and comfort.
Mechanical Resistance
The well-known high mechanical strength of graphene, with a Young’s modulus of ~1100 GPa and a tensile strength of 42 N/m, makes a single layer of graphene 200 times stronger than steel of equal thickness. This strength can be utilized in graphene-modified composites, enabling them to withstand significant forces without deformation, achieving greater strength with a smaller gauge. In wool fabrics, excellent linearity with over 20% elongation, moisture resistance from 30 to 90%, and good electrical and mechanical properties have been observed.
Barrier Properties
The hydrophobic nature of graphene, the size of its nanochannels, and the high electron density on its surface make it highly impermeable to particulate matter, liquids, and gases. Graphene compounds interact with other materials and molecularly organize their three-dimensional structure, creating compounds that are not only impermeable but also mechanically stronger and with significant recovery or deformation resistance.
Antimicrobial Barrier
Graphene’s antimicrobial capability is advantageous in the textile industry, considering the persistent challenge of microorganism anchoring, proliferation, and spread on garments, especially in the medical sector.
Antimicrobial Barrier Mechanisms
– Size Exclusion: The interatomic distance of carbon atoms in graphene (0.142 nm – 0.9 nm) provides a barrier that microorganisms, with sizes ranging from 10 nm to 3 micrometers, cannot permeate.
– Oxidative Stress: Interactions between the polar ends of phospholipids in cell membranes and graphene generate irreversible oxidative stress and microbial death. Its strong protein anchoring capability can inhibit the enzymatic capacity of some microorganisms.
– Membrane Damage: The sharp edges of graphene layers physically damage the structure of microorganisms, preventing microbial adhesion to surfaces without adverse effects on the skin.
UV Protection
Graphene’s absorption spectrum covers the entire electromagnetic spectrum, with a peak absorption around 281 nm, allowing it to absorb UV radiation with a wavelength between 100 and 281 nm. For wavelengths longer than 281 nm, graphene’s reflective properties play a crucial role in UV radiation resistance and, consequently, in the increased durability of materials exposed to the elements.
Comfort
Traditional textiles like cotton, linen, or silk are highly hydrophilic but have limited water molecule transport capacity. The hydrophobicity of graphene compounds prevents water transport to the inner layer and simultaneously transports water inversely to its outer surface. Its excellent thermal regulation capability prevents the concentration of heat and moisture, creating an environment inhospitable for the proliferation of microorganisms, thus preventing infections, stains, and unpleasant odors.
At Energeia-Graphenemex®, leaders in Latin America in graphene production and development, we are convinced of the tremendous potential of this material to meet the needs of industrial sectors such as the textile industry. We are committed to addressing the scientific, technical, economic, and ethical needs of each project, serving as a strategic ally for companies seeking to innovate and improve their products and processes through the integration of graphene technologies. We look forward to introducing the first graphene textiles in Mexico soon.
Redaction: EF/DH
References:
Part I
Graphene, a two-dimensional nanomaterial made of carbon atoms, is revolutionizing materials science and nanotechnology. It stands as the only known material that combines a myriad of thermal, electrical, mechanical, optical, and other properties. Moreover, it can integrate with other structures, sharing and significantly enhancing their original characteristics. Since its isolation in 2004, researchers and industries worldwide have sought to leverage its extraordinary benefits. However, high production costs and challenges in obtaining sufficient quantities for industrial applications have hindered widespread market adoption.
Despite these challenges, the textile industry has not remained idle in the face of the opportunities presented by graphene nanotechnology. Over the last decade, it has explored not only graphene but also other nanomaterials like copper nanoparticles (CuNp’s), silver (AgNp’s), gold (AuNp’s), zinc oxide (ZnO), titanium dioxide (TiO2), and carbon nanotubes, among others. The goal is to imbue textiles with antimicrobial properties, flame retardancy, mechanical strength, electrical conductivity, and various other attributes. The key difference lies in graphene’s multifunctional capabilities; it can provide or enhance more than one benefit simultaneously.
What Benefits Does Graphene Offer in the Textile Industry?
Graphene boasts an extensive and complex list of properties, ranging from mechanical to barrier-related, making it highly attractive for numerous applications. In the textile industry, initial interest focused on its electrical and thermal conductivity. However, extensive research has unveiled a wide array of benefits correlating with its multifunctionality.
It’s crucial to note that the extraordinary characteristics of graphene, as described in the literature, often pertain to measurements conducted on nanomaterials in their pure form. To truly capitalize on their benefits in tangible applications, it’s necessary to combine them with three-dimensional materials capable of transferring their properties. Polymeric matrices have proven highly efficient as a support for graphene materials, with interfaces that are strong and stable facilitating superior property transfer.
How Does Graphene Interact with Textile Materials?
At the nanoscale, interaction mechanisms depend on multiple factors and generally involve electrostatic interactions, Van der Waals forces, hydrogen bonding, π-π interactions, or hydrophobic interactions. On the macroscale, understanding this interaction is contingent on the type of graphene, textile material, and the integration method or timing. The latter is particularly crucial because having the right graphene is not sufficient; anchoring and permanence throughout the structure of natural or synthetic textile fibers are variables that increase complexity.
In many cases, additional chemical modifications to graphene are necessary, and the implementation of other additives for charge modification is considered. Various technologies, such as vacuum infiltration, pressing, or dyeing methods, may be employed to improve interaction. However, these methods may be superficial, and achieving mechanical or flame-retardant benefits may require further chemical modifications or the use of specific technologies.
Due to the breadth of the topic, this article is divided into two sections. In this first part, we will discuss the uses of electrical, thermal (fire resistance), and mechanical properties of graphene in textiles. The next publication will conclude the description of barrier properties, protection against UV radiation, and comfort.
Electrical Conductivity
Graphene’s high electrical conductivity is fascinating for manufacturing smart textiles incorporating sensors, microprocessors, light indicators, fiber optics, etc. Applications extend to textiles with electromagnetic and antistatic protection, with potential uses in industries like oil, mining, military, and medicine. Graphene’s corrosion-free, lightweight, and flexible nature sets it apart from metallic fibers.
Studies have explored incorporating digital or electronic components into garments, such as glucose monitors, heart rate monitors, gas sensors, tension and torsion monitors, motion sensors, acoustic sensors, pulse sensors, or even solar energy harvesting.
Thermal Conductivity
Graphene’s well-known thermal conductivity benefits the rapid dissipation of heat in various materials, including textiles. Its integration into viscoelastic materials for mattresses or textiles used in summer garments helps maintain thermal balance associated with comfort and rest. Therapeutic applications are also being studied to stimulate blood circulation and aid muscle recovery from fatigue.
Graphene textiles have been used as heating elements in industrial and residential heating components such as carpets, car seats, and de-icing systems for aircraft access routes. Graphene, being corrosion-free and allowing for lower weight, offers additional advantages over metallic heating elements.
Fire Resistance
The thermal stability of graphene materials depends on their chemical structure and can range from 500°C to 3000°C. However, these conditions may vary when functionalized or combined with other materials. In certain cases, graphene can increase the decomposition temperature and ignition time. Graphene acts as a gas barrier due to its tortuous internal structure, reducing the diffusion of combustible gas to the flame source, inhibiting oxygen diffusion, delaying initial combustion, and preventing re-ignition. Graphene improves the thermal stability of polymers by decreasing the heat release rate, preventing fire spread, and reducing ignition time.
While some polymers with graphene may accelerate ignition time, once a carbon layer forms, it covers the polymer’s external surface and protects the sublayer from fire spread. Graphene’s chemical composition is free of halogens, eliminating the release of furans and dioxins that cause environmental issues.
At Energeia-Graphenemex®, leaders in Latin America in graphene production and development, we believe in the tremendous potential of this material to meet the needs of industrial sectors such as the textile industry. We are also aware of the scientific, technical, economic, and ethical needs inherent in each project. As a strategic ally, we collaborate with companies interested in innovating and improving their products and processes by forming multidisciplinary teams to pave the way for the introduction of new technologies like graphene into the market. We look forward to soon seeing the first graphene textiles in Mexico.
Redaction: EF/DH
References:
Within the framework of the long-awaited 3rd Global Webinar on Nanotechnology and Nanoscience, scheduled for February 27 and 28, 2024, it will feature the outstanding participation of Eduardo Priego Mondragón, CEO of Graphenemex México, as one of the main speakers.
Under the theme “Insights and Innovations in Nanotechnology and Nano Science: Progressing to the future”, this event, organized by the Global Scientific Guild, is presented as a unique platform for the exchange of knowledge between experts and delegates from industry and academia.
The inclusion of Graphene Oxide (GO) in coatings demonstrates effectiveness in inhibiting flammability, providing a fire-resistant barrier. Benefits include anti-corrosion protection, antimicrobial properties and increased adhesion to substrates. This advance highlights Energeia-Graphenemex’s innovation in the production of fireproof coatings, positioning itself as a leader in the research and application of high-quality graphene materials.
Coatings are used in various sectors, at an industrial level the use of coatings are focused on protection against corrosion, while at a commercial level they are used for infrastructure maintenance and for decorative purposes. Today, the coatings industry continues to constantly research the development of improved coatings, with antimicrobial, non-stick properties, and greater resistance to chemical attack and weathering. However, at a commercial level there are few developments focused on fireproof coatings (flame retardant) for fire protection in infrastructure.
Traditional fireproof coatings are cementitious coatings, based on Portland cement, magnesium oxychloride cement, vermiculite, gypsum and other minerals. In addition, they contain fibrous fillers, binders, supplements and additives that control density and rheology, these materials are generally mixed with water on site and applied by spraying some construction or can be applied to a flammable substrate by using a roller, in thicknesses of half an inch or more. However, due to their weight, thickness and poor aesthetics, they limit architectural design.
In coatings and paint industry, there is a wide variety of coatings based on different types of resins (polymers) and additives. Due to their nature, most of these coatings are flammable and combustible materials. That is, they are materials that can catch fire when exposed to fire, suffering degradation and the release of heat to subsequently initiate the spread of the flame, releasing smoke and toxic gases, being a danger to the safety of human life and property. On the other hand, polymer-based fireproof coatings use conventional additives based on halogens (bromine and chlorine), as well as phosphorus, melamine and inorganic compounds, to improve the fire resistance of the coatings, however, these materials are toxic to humans and the environment.
In recent years, Energeia-Graphenemex has focused on the production of graphene materials. Graphene is the most revolutionary nanotechnological additive for the coatings and paints industry, as it allows the development of coatings with extraordinary anti-corrosion protection, coatings with antimicrobial properties, coatings with better adhesion to substrates and greater resistance to UV radiation. In this sense, graphene oxide (GO) has been shown to be a new additive that helps inhibit or reduce the flammability of coatings, to produce effective fireproof coatings.
Its efficiency is associated with the fact that GO has a strong barrier effect, high thermal stability and great surface absorption capacity that are favorable for effectively reducing heat and mass transfer.
The incorporation of GO in coatings can improve flame resistance, by inhibiting the two key terms: heat and fuel. That is, it can function as a flame retardant in the following ways:
• GO possesses a unique two-dimensional layer structure and can promote the formation of a dense continuous layer of carbon during the combustion process (see Fig. 1). Carbon can act as a physical barrier to prevent heat transfer from the heat source and delay the escape of products (pyrolysis) from the coating.
• Because GO has a large surface area, it can effectively adsorb flammable volatile organic compounds or hinder their release and diffusion during combustion.
• The presence of oxygenated groups in the GO structure means that, during the combustion of the coating, the oxygen-containing groups in GO can undergo decomposition and dehydration at low temperature, thus absorbing heat and cooling the polymeric substrate during combustion. Meanwhile, gases generated by dehydration can dilute the oxygen concentration around the ignition periphery, decreasing the risk of fire spread.
In summary, the incorporation of GO in coatings can provide fire protection, because they can release water and provide thermal insulation effects.
Graphene-based flame-retardant coatings are designed to retard ignition and burn rate, and must provide a fire-resistant barrier.
Energeia – Graphenemex®, Mexican company, leader in Latin America in research and production of graphene materials for the development of industrial applications. It has extensive experience in the large-scale production of graphene oxide (GO) and has high-quality graphene materials for sale for use in different industries.
References
Tribology is the science that studies friction, wear, and lubrication, both of natural and artificial systems in relative motion. Its study is important since all the mechanical systems in motion that surround us consume large amounts of energy due to friction. This can lead to structural deformation and fatigue, or cause crack initiation and propagation that ultimately leads to the formation of loose wear debris in the mechanisms.
As surfaces wear, they become rougher and highly reactive due to the formation of defects, causing greater energy dissipation, becoming a highly damaging cycle. This is because when one surface slides tangentially over another, there is resistance to movement caused mainly by interference between the roughness, sometimes macroscopic, between two surfaces. This resistance is called friction and occurs in the form of wear, increased temperature, and deformation. Even in the presence of a lubricating film, when the load capacity is large or the sliding time is long, the lubricating film loses thickness breaks, generating heat and friction, causing significant failures in the parts of metallurgical equipment.
“Friction and wear not only affect the operation and maintenance of industrial equipment, but the energy loss caused by these phenomena accounts for 1/3 of the world’s industrial energy consumption, while 80% of failures in pieces result in important economic impacts.”
Extensive research on the tribological properties of graphene and its derivatives has positioned it as an important two-dimensional nano-lubricant element, with anti-friction, anti-wear and anti-corrosive effects due to the following mechanisms:
• Nanometric Protective Layer: Graphene sheets, thanks to their lamellar morphology and surface energy, form a protective film that prevents direct contact between sliding surfaces. This shield minimizes friction and wear, even at micro and nano levels.
• Continuous Sliding: The weak bonds between graphene sheets allow continuous sliding, avoiding contact between moving surfaces. When these bonds are broken, the sheets are redistributed, maintaining the integrity of the protective film.
• Suppression of Degradations: Graphene suppresses abrasive, adhesive and corrosive degradation, reducing friction and preventing wear.
• Energy Dissipation Mechanisms: The stretching and bending of graphene compounds act as efficient energy dissipation mechanisms.
Theoretical studies suggest that, as temperature increases, the friction force decreases due to the accumulation of charge between carbon and hydrogen atoms, generating electrostatic repulsion. These properties have led to friction coefficients from 0.05 to 0.0003, without significant surface wear.
Energeia-Graphenemex®, a pioneer company in Latin America, stands out for its focus on the industrial development of graphene. Its experience in creating affordable, large-scale production methods ensures the availability of graphene materials for various applications, from its own products to strategic collaborations with other companies seeking to incorporate graphene technology into their products.
An important point to consider is that the effectiveness of graphene materials does not only lie in their simple presence within a new material, but that is also, to improve their performance as a lubricant, additional chemical modifications may be required, e.g., with nitrogen, elements. metals and their oxides, polymers, compounds such as molybdenum disulfide, boron nitride, dimanganese tetraoxide, stearic acid, oleic acid, alkylamine, among others that are being studied. At Energeia-Graphenemex® we hope to soon have the first graphene lubricant available in Mexico.
Drafting: EF/DH
References
Fiber reinforced concrete is an improved version of conventional concrete characterized by better performance against cracking, deformation, fatigue and impact. It is widely used for the manufacture of industrial and commercial floors, tunnels, slopes, tanks, shotcrete, prefabricated and in some cases as a replacement for the electrowelded mesh of floors, but not as a substitute for the reinforcing steel of structural columns, load-bearing walls. or suspended beams. Unlike concrete reinforced with steel structures, fibers represent a discontinuous and homogeneous three-dimensional reinforcement within the concrete mixture that allows it to have the same characteristics at each point of the structure.
Of the extensive classification of fibers in terms of materials, lengths, thicknesses and geometries, the main competition is between steel fibers and polypropylene fibers, because both materials increase the toughness of concrete and allow it to continue absorbing loads before collapse. The difference is that steel fibers control cracking during the setting of the concrete and after hardening, they have great tensile strength and do not deform, but rather absorb energy and transform it into an internal stress; characteristics that make them very useful for use in concrete exposed to high loads. Polypropylene fibers contribute to the control of cracks due to plastic contraction, external loads, temperature, or drying contraction and, although its tensile strength is lower than steel, its deformation capacity allows it to absorb large loads without failing. They are less expensive, easier to handle and are generally indicated for lower load concretes.
Although the mechanical properties of steel fibers are superior to those of polypropylene and subject to the characteristics of the project and the applicable regulations, there are other technical differences that are worth considering when selecting:
Durability- The steel fibers within the concrete usually remain stable and isolated from the external environment, however, when this insulation is broken either by capillarity, microcracking or by a change in the pH of the concrete, the fibers become susceptible to corrosion, whose oxidation in the future will be responsible for the loss of adhesion with the concrete. The advantage of polypropylene fibers is that they are suitable for placement in humid and marine environments thanks to their chemical stability, resistance to corrosion and degradation.
Volumetric weight- The amount of polypropylene fibers per kilogram of weight is greater than those contained in one kilogram of steel fibers. This means that, to have a similar distribution, approximately between 5 and 8 kg of metallic fibers should be dosed for each kilogram of polypropylene fibers and, although the volumetric weight can be considered irrelevant for performance, the cost and handling of the product can be two interesting variables.
Adhesion – The adhesion or interfacial bond between the fiber and the concrete is essential for the long-term success of the structure and is quantified as the force necessary for the fiber to be torn from the concrete matrix or undergo rupture. In steel fibers, their adhesion depends mainly on their morphology and length; however, polypropylene fibers, in addition to facilitating the manufacture of different configurations, can also be chemically modified to improve their adhesion.
Distribution- Depending on the quantity dosed, steel fibers can form “hedgehogs” or leave spikes on surfaces, posing risks during handling and after placement. A disadvantage of polypropylene fibers is their hydrophobicity or incompatibility with water, this means that when the mechanical mixing of the fibers is carried out within the concrete composed of water, cement and aggregates, they can agglomerate and cause clumps, especially at dosages. elevated; Consequently, poor distribution, aggregation or formation of air spaces within the concrete will have a negative impact on its adhesion and, therefore, its performance.
Fire resistance – In the event of a fire, concrete can exhibit explosive detachment or “spalling” behavior, which consists of the violent expulsion of fragments due to the increase in pressure exerted by the release of water vapor until detachment occurs when the pressure exceeds the tensile strength of the concrete. Polypropylene microfibers melt at temperatures between 160 and 170° C, therefore creating interconnected channels that increase the permeability of the concrete and help release moisture and internal pressure.
The Mexican company Energeia-Graphenemex®, through its Graphenergy Construction division, takes advantage of the benefits of graphene nanotechnology to improve the characteristics of conventional polypropylene fibers; Its specialized formula allows obtaining individual filaments with greater mechanical and thermal resistance, better distribution and greater adhesion within the concrete compared to common fibers.
How does graphene oxide improve the performance of polymer fibers?
Graphene oxide is one of the most interesting materials to improve the characteristics of many polymers. It consists of sheets of graphene or pure carbon stabilized with oxygenated groups that make it a multifaceted structure, compatible with water, like cement crystals and easily combinable with other compounds to design materials with new or improved properties, for example:
Distribution within the concrete mix
One of the advantages of graphene oxide designed for the manufacture of polypropylene fibers is its surface chemistry consisting mainly of oxygenated groups (OH- and COOH-) that help maintain the affinity of the fibers with the aqueous elements of the graphene paste. cement acting in a similar way to plasticizing additives, this is because graphene oxide reduces the surface energy of the fibers, facilitating their distribution within the mixture and avoiding aggregates.
Adherence
Another benefit of graphene oxide present in polypropylene fibers is the electrostatic repulsion that it generates between the cement particles; This phenomenon prevents cement agglomeration and increases the degree of fiber-cement interaction by altering the hydration products and increasing their degree of polymerization. In hardened concrete, this effect increases the coefficient of friction so that when a crack displaces a fiber, more load will be required to displace it within the concrete.
Mechanical strength
Graphene oxide increases the tensile and breaking strength of polymers, this is because its elastic modulus (230 GPa) is slightly higher than that of steel and its alloys (190-214 GPa), but comparable to of Zirconia (160-241 GPa) and Cobalt alloys (200-248 GPa), therefore, fibers with graphene oxide have a lower risk of fracture and are more durable than common fibers
Degradation resistance
Polymeric fibers with graphene oxide have a longer useful life because it is a material that differs from many others that deteriorate because of UV radiation, graphene oxide maintains its structural integrity and mechanical properties, in addition, it is chemically inert. and more resistant to corrosive media.
Thermal stability
Graphene oxide increases the thermal stability of polypropylene by forming interconnected bridges or pathways throughout the polymer matrix, improving heat transport.
Drafting: EF/DH
Sources
Globally, concrete is the most used construction material. Concrete is applied in different infrastructures, including buildings, bridges, dams and tunnels, due to its high compressive strength. However, concrete has some limitations and problems, such as low tensile strength and cracking. Cracks or fissures can appear during the production of concrete and at subsequent stages. They begin as nanoscale cracks, later they join together forming micro and macro cracks. This behavior is closely associated with the hydration process that cement undergoes, where it releases heat and increases the temperature of the concrete. In large structures, heat cannot be released easily, causing expansion stresses, and thermal contraction, leading to cracking.
Because concrete is constantly exposed to impact, fatigue and other types of loads, cracks or fissures, and irreparable failures can occur, it is why it is common to reinforce it with polymer fibers to improve the physical-mechanical characteristics of concrete.
Incorporating fibers into concrete has proven to be effective in delaying or preventing crack propagation. At a commercial level, there is a wide range of polymeric fibers as three-dimensional secondary reinforcement of concrete and mortar, with different lengths and sizes (macrofibers and microfibers). These polymer fibers are made from materials such as polypropylene (PP), high-density polyethylene (HDPE), PVA and polyester.
However, there are some disadvantages or limitations of commercial polymer fibers, the hydrophobic nature of polymer fibers, or/and its elastic modulus is insufficient, so the incorporation of polymer fibers in concrete only slightly improves the resistance to the tension. Furthermore, the little improvement in tensile strength is mainly attributed to insufficient bond strength at the interface between the fiber and matrix, i.e., low compatibility (no adequate anchorage) of the fiber with the concrete. So the fibers easily detach from the concrete, increasing the risk of cracking and failure in the concrete. (See Figure 1)
Currently Energeia Fusión- Graphenemex, under its Graphenergy Construction line, developed polymeric macrofibers with graphene oxide (GO). Graphene oxide is a nanomaterial, which due to its unique physical and chemical characteristics, such as its large surface area (736.6 m2/g), extraordinary mechanical properties (25 GPa), thermal properties and its unique structure with multiple oxygen-containing groups on its surface, makes GO an ideal material for modifying the surface of polymer fibers. These characteristics allow improving the interface or compatibility of the fibers with cementitious materials and/or concrete.
The oxygenated groups of GO act as anchoring sites for the formation of cement hydration products, improving the interface between the fibers and the cementitious matrix (See Figure 2). Consequently, a stronger interface leads to an improvement in the tensile strength of the concrete.
When a concrete structure is subjected to loading, tension and compression stresses begin to build up. Over time, small cracks appear in places where the stress reaches a critical point. In this sense, the Graphenergy reinforcing fibers remain solidly anchored in the concrete matrix and absorb the tensile stress at any point and direction.
If there is a small crack the fibers are held firmly within the concrete, as the tension increases the fiber slowly elongates (deforms) until it reaches its maximum strength. With a 38% improvement in tensile strength and 29% more elongation than commercial reinforcement, concrete structures reinforced with Graphenergy fibers can withstand high bending stress over a long period. These nanotechnology fibers delay the appearance of the first crack and slow down the spread of cracks in the concrete.
The main difference between Graphenergy reinforcing fibers and other commercial fibers is that fibers with graphene become part of the concrete matrix and give rise to a composite material. Graphenergy reinforcing fibers form a reinforcing network throughout the structure, reducing or inhibiting the appearance of cracks (effective crack control), and improve the ductility of concrete. Additionally, Graphenergy reinforcing fibers improve concrete quality, providing greater shrinkage resistance, fire resistance and greater impermeability in concrete.
References
What is corrosion?
The term corrosion refers to the destruction of a material because of its chemical or electrochemical interactions with the surrounding medium. The importance of its prevention and/or control is due to the fact that, being a natural phenomenon, once started it is practically impossible to stop. Therefore, an uncontrolled evolution will invariably compromise the integrity and useful life of the materials, generating the industry involved direct and indirect expenses due to loss of product, stoppage of activities due to maintenance until the replacement of machinery or structures.
“Economic losses caused by corrosion exceed 3.4% of global GDP”
Microbiologically influenced corrosion
Microbiologically influenced corrosion (MIC) can be defined as the electrochemical process in which microorganisms such as algae, fungi and bacteria initiate, facilitate, or accelerate a corrosion reaction, generally located in the form of cracks. or pitting on both metal and concrete surfaces. Although corrosion involves various variables, it is estimated that MIC participates in 20 to 40% of all corrosion failures, particularly in hydraulic and oil infrastructure, with costs close to 2 billion dollars annually.
Why do you start the MIC?
The presence of humidity in any environment is the ideal habitat for the growth of numerous communities of microorganisms that, combined with optimal conditions of temperature, pH, nutrient flow, etc., promotes their adhesion and growth on surfaces, forming a biofilm that is not removed, it grows into a hardened, obstructive biomass within which sulfate-reducing bacteria, acid-producing bacteria, iron-reducing bacteria, and gel-forming bacteria promote corrosion or MIC through destructive electrochemical reactions of the surfaces.
How do you combat it?
There are three most common methods to try to combat MIC, the first is mechanical cleaning of surfaces to remove biofilms, ideally in incipient stages, however, it is not always possible to access all exposed areas, making their efficiency difficult. The second is the use of biocidal agents that, in addition to being expensive, most may not be friendly to human health and the environment. Finally, and perhaps the most suitable method is the placement of external barriers in the form of coatings or polymeric films to prevent direct contact of the metal or concrete structures with the aggressive medium.
Corrosion control in concrete
The options available to protect concrete against corrosion from its fresh state are the additions of pozzolanic materials, fly ash, blast furnace slag, sulfate-free aggregates, polymer fibers, use of sulfate-resistant cement or modified with nanoparticles such as nanotubes and carbon nanofibers, silica nanoparticles, alumina or titanium dioxide. For protection in the hardened state, it is common to apply physical barriers such as anti-corrosion coatings or polymeric films and, for the protection of metal structures, in addition to anti-corrosion coatings, you can use galvanized, tinned structures or the placement of magnesium sacrificial anodes. However, it is considered that, due to the natural porosity of concrete, there are no totally efficient methods that attack the problem of corrosion towards the interior of structures.
Corrosion in concrete can occur due to carbonation, ingress of chlorides and sulfates or due to microbiological attack. When the concrete has reinforcing steel and is attacked by corrosion, oxide can grow 2 to 4 times the volume of the original steel, causing loss of adhesion of concrete and put the resistance of the material at risk. Furthermore, the porosity of the concrete, in addition to allowing the passage of moisture for the entry of aggressive ions, also offers millions of ideal niches for the retention of microorganisms and for the subsequent formation of MIC-initiating biofilms, not only because they favor their anchoring, but because they make their removal difficult and promote the advancement of corrosion.
“It is expected that by 2032 the corrosion inhibitors market will amount to 12.5 billion, and in 2022 this figure will be around 8.3 billion.”
Graphene and graphene oxide are multifunctional carbon nanomaterials with extraordinary properties that, when incorporated as a nanofiller in other compounds such as coatings, plastics or cement, have the ability to molecularly organize their structure in such a way that they improve their resistance to chemical, physical and microbiological attacks. Among their particularities is that they are inert nanostructures, that is, they are stable, they do not react with other materials and they do not suffer oxidation or corrosion. They are extremely thin and light, but at the same time, very resistant and flexible. They are impermeable even to gases and have highly efficient antimicrobial mechanisms.
Below is a summary of some of the most notable research on the use of graphene as an alternative against microbiologically influenced corrosion (MIC):
2015- The Department of Materials Science and Engineering at Rensselaer Polytechnic Institute, New York, USA, modified polyurethane coatings with graphene identifying 10 times greater protection against MIC compared to unmodified polyurethane coatings.
2017- The Nanobiomaterials laboratory of the Federico Santa María Technical University, Valparaíso, Chile, evaluated the direct effect of graphene placed on nickel substrates and its interaction with bacteria that cause corrosion. The results showed an impermeable barrier generated by graphene that blocked the interaction between bacteria and the metal, but without a bactericidal effect.
2021- The Department of Civil and Environmental Engineering, South Dakota School of Mines and Technology, USA, reported that multiple layers of graphene restricted MIC attack on copper and nickel surfaces 10 times more.
2021– The School of Engineering at the University of Glasgow, Scotland, examined the deterioration of graphene oxide (GO)-modified cement pastes exposed to acidic environments. The results demonstrated that the presence of GO reduces the loss of mass in the concrete due to these attacks, recognizing it as a potential additive to modify the microstructure and useful life of concrete in the face of aggressive environments such as those present in chemical product warehouses to systems. of wastewater.
Energeia Fusion (Graphenemex®), the leading Mexican company in Latin America in the production of graphene materials, after a long journey of research, in 2018 launched the Graphenergy Line on the market, which includes a series of anticorrosive and antimicrobial coatings with graphene nanotechnology and the first additive for concrete with graphene oxide in the world, whose individual or combined use promises great benefits against corrosion.
Graphenergy Construction is a water-based additive with graphene oxide designed to improve the quality of cement structures in terms of mechanical resistance and durability. The added value that graphene oxide offers to concrete in the fight against MIC from the outside to the inside is the result of a series of events that begin by favoring the hydration of the cement, acting as water reservoirs and as a platform for the growth of crystals. of C-S-H and to dissipate the heat of hydration; improves the interfacial transition zones between the cement paste and the aggregates, helping to reduce the size and volume of the pores, this in turn favors an increase in mechanical resistance, reduces permeability, increases its resistivity, that is, reduces the transfer of electrical charges into the interior of the concrete, delaying the onset of corrosion and, finally, modifying the electrostatic charges and the wettability of the surfaces, making the formation of biofilms that cause MIC difficult.
Graphenergy coatings formulated with graphene oxide offer great resistance against corrosion in coastal and non-coastal areas, as well as excellent antimicrobial protection without biocidal mechanisms, since their effect consists of preventing the adhesion of microorganisms to surfaces. In addition, its impermeability, resistance to abrasion and resistance against the intense effects of the elements increase its useful life and, therefore, substantially reduce the maintenance costs of both metal and concrete structures.
Drafting: EF/DH
References
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