An adhesive is a substance that allows them to stick together and withstand detachment when deposited to the surfaces of two or more components. Nanomaterials such as nanofillers, nanotubes or nanosheets, inorganic nanoparticles, and others are being developed and commercialized, opening up new options for tailoring adhesives in the nanometer range.
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Nanoparticles are increasingly being used in polymeric materials and structural adhesives due to their growing processability and lower pricing. Because of the enormous surface area of nanomaterials, little is required to create substantial alterations in the hybrid adhesives' characteristics.
It could lead to a new class of structural adhesives with a mix of thermal, electronic, and mechanical capabilities that are also more environmentally durable due to lower moisture absorption and improved aging qualities.
Incorporation of Nanofillers in Adhesive Bonding
Organic and inorganic additives such as nanotubes, cellulose nano-crystals, nanofibers, nano-alumina, and nano-silica are often used to modify adhesives. Nanoparticles have attracted a lot of attention due to their unique features.
Nano-fillers provide several advantages over traditional micro-reinforcements for adhesives: the presence of nanomaterials allows for thinner bonding lines and, as a result, a lesser danger of embrittlement inside bulk adhesive formulations, which can result in increased strength properties.
Why Nanostructured Reinforcement
Materials ranging from 1 to 100 nanometers are referred to as nanomaterials, which can be used to manufacture nanoparticles (NPs).
As a nanoparticle's dimension approaches zero, the fraction of the particle's surface to overall atoms increases. The physical properties of NPs are unmatched at the macroscale. As a result, several scientists are concentrating on modifying sticky characteristics with NPs.
When doing so, it is important to think about the target adhesive qualities, adhesion and NP interaction, NP performance, and service circumstances.
Methods to Fabricate Nano-Based Adhesives
The use of effective dispersion technologies, as well as the surface functionalization of the nano-fillers, can help to achieve uniform dispersion for fabricating nano-based adhesives. Hydraulic blending, ultrasonic treatment techniques, and hybrids of these two approaches have all been utilized to disperse nano-fillers into the adhesives in a wide variety of applications.
Mechanical Properties of Nano-Based Adhesives
Nano-fillers have been shown in studies to improve bulk mechanical properties, interfacial bonding, and adhesive bonding lifetime. The main goal is to maximize fracture resistance without sacrificing adhesion.
The application of nano-reinforcements to brittle polymers (thermosets) has a lot of potential. Rubber additives improve the durability of these delicate resins, but they diminish other mechanical characteristics.
Adding nanofillers, such as carbon nanotubes, to adhesive bonding improves their toughness, according to numerous studies. Unique crack energy usage mechanisms such as crack bending, fracture spanning, and filament pull-out are assumed to be responsible for the toughening effect of nano-reinforcement addition.
Electrical Properties of Nano-Based Adhesives
Carbon nanotubes or carbon nanofibers as additives in electrically conductive adhesives are among the most exciting electronic applications. The goal is to make electrical adhesives work better than current products.
With increased CNT or CNF concentration, these nanomaterials display evident infiltration behavior, improving electrical conductivity. Infiltration values change based on nano-reinforcement composition, generally lower for CNT than CNF.
The dispersion process has a significant impact on the conductivities of nano-composites. High-energy dispersion can harm nanofillers, reducing their aspect ratio and affecting percolation.
Applications of Nano-Based Adhesives
Due to its capacity to connect a variety of materials such as metals, semiconductors, plastics, and composite materials, the nano-based adhesive bonding technique has gained popularity in recent years.
Due to its minimal specific density, affordability, superior damping qualities, and homogeneous strength throughout the joint, nano-based adhesive bonding can be used in various fields, including automobile, aerospace, and electronic parts.
Nano-Based Adhesives for the Aerospace Industry
The design and deployment of sophisticated nanotechnologies are expected to bring a significant transformation to the aircraft sector in the not-too-distant future.
Nano-based adhesives for the aerospace sector are particularly significant due to the specific benefits that such breakthroughs could bring to the industry. Aerospace design would benefit greatly from the capacity to create lighter and smaller solutions while simultaneously maximizing critical features such as strength and corrosion resistance.
Conclusion
The addition of nanofillers improves characteristics of many adhesives significantly, although the results are dependent on a variety of parameters, including the type of the adhesive, the performed surface preparation, and the evaluated characteristic. They are also dependent on the type and quantity of nanofiller. In general, it appears that there is a nanofiller concentration at which the adhesive characteristics evaluated are at their peak.
Continue reading: What are Epoxy Nanocomposites?
Reference and Further Reading
Jojibabu, P., Zhang, Y. X., & Prusty, B. G. (2020). A review of research advances in epoxy-based nanocomposites as adhesive materials. International Journal of Adhesion and Adhesives, 96, 102454. https://linkinghub.elsevier.com/retrieve/pii/S0143749619302039
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