Updated by Reginald Davey 03/03/2023
Nanocomposites have several advantages over conventional filler counterparts and base polymers. This is due to the supremely beneficial properties of nanocomposites and improvements to the properties of alternative, conventional materials.
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This article will discuss the preparation, properties, and application areas of nanocomposites. It will also explore some recent innovative uses for these novel materials.
Nanocomposite Preparation
Nanocomposites are defined as composite materials with two or more components, where at least one is a nanomaterial. Nanocomposite materials are made by embedding a reinforcing phase into a matrix phase. Either phase can be the nanomaterial.
Correct preparation produces a composite material that retains both the matrix’s toughness and the reinforcement material’s strength. The matrix is typically a tough or ductile material, whereas reinforcing materials have low density but high strength.
Synthetic methods are commonly employed to prepare nanocomposites, such as lamination, soft lithography, solution casting, and spin-coating. Homogenous nanoparticle dispersion is a primary challenge during preparation. Dispersion affects phase interfaces and the final nanocomposite properties.
Different materials, structures, and compositions allow for fine-tuning of nanocomposite properties, such as electrical, mechanical, thermal, acoustical, and magnetic properties. Nanocomposites have given rise to the field of multifunctional materials.
Research has indicated that molecular-level interactions between matrix and nanoparticles alongside the high matrix-nanoparticle interfacial area is key to influencing the mechanical and physical properties of nanocomposites.
Enhanced Nanocomposite Properties
The vastly improved properties of nanocomposites include:
- Mechanical properties, e.g., strength, modulus, and dimensional stability
- Decreased permeability to gases, water, and hydrocarbons
- Thermal stability and heat distortion temperature
- Flame retardancy and reduced smoke emissions
- Chemical resistance
- Surface appearance
- Electrical conductivity
- Optical clarity in comparison to conventionally filled polymers
Nanocomposite Disadvantages
Traditional issues with nanoparticle incorporation into materials include impact performance and toughness. Research has indicated that modifying polymers such as polyamides with nanoclay particles reduces the impact performance of the produced nanocomposite materials.
This is a critical issue, especially in applications where impact loading events are likely to occur. Better understanding of the relationship between the formulation, structure, and properties of nanocomposites is necessary to improve their application potential. Additionally, optimal routes to platelet exfoliation and dispersion are vital.
Particle Loadings
Nanoparticulate loading confers significant property improvements at extremely low loading levels. Conventional microparticle additives require much higher loading levels to achieve similar performance to nanocomposites.
Consequently, this results in significant weight reductions, which is important for applications in areas such as aerospace and the military. Additionally, this gives nanocomposites greater strength at similar structural dimensions and, for barrier applications, increased barrier performance at comparable material thickness.
Mechanical Property Gains Due to Nanoparticle Additions
Polyamide-montmorillonite nanocomposites display significantly enhanced properties. Tensile strength in these materials is improved by approximately 40% at 23oC and 20% at 120oC. Modulus improvements of up to an impressive 220% have been observed in these nanocomposites.
Heat distortion temperature in the unmodified polyamide increases from 65oC to 152oC in the nanoclay-modified material. Only 5% loading with montmorillonite clay is necessary to achieve these vastly improved properties. Similar enhanced properties have been observed in polymethyl methacrylate-clay nanocomposites.
Nanoclays can also be combined with conventional fillers such as long/short glass fibers, providing unique benefits and property enhancements for polymeric nanocomposites.
Application Areas
Nanocomposites have received major interest in several application areas due to their mechanical property improvements. Numerous automotive, industrial, and commercial uses have been explored in depth in recent decades.
Application areas in the automotive industry include engine covers, intake manifolds, door handles, mirror housings, and timing belt covers in various vehicle types. Applications in other commercial areas include vacuum impellers and blades, mower hoods, mobile phone covers, and power tool housings.
Use in the Food Packaging Industry
The superior barrier properties of nanocomposites have led to widespread interest in their use in the food packaging industry. Adding nanoclays to polylactic acid- and polypropylene-based film packaging prevents the diffusion of gases and flavorings. By providing enhanced barrier properties for films, shelf life is increased
Nanocomposites have also been applied in food packaging to provide functional properties such as enhanced antimicrobial behavior. Nanosilver has been widely explored as an antimicrobial agent added to plastic composites, preventing food spoilage.
Thin Films
The presence of filler incorporation at nano-levels has also been shown to have significant effects on the transparency and haze characteristics of films. In comparison to conventionally filled polymers, nanoclay incorporation has been shown to significantly enhance transparency and reduce haze.
With polyamide-based composites, this effect has been shown to be due to modifications in the crystallization behavior brought about by the nanoclay particles; spherulitic domain dimensions being considerably smaller.
When employed to coat polymeric transparency materials, nano-modified polymers enhance both toughness and hardness without interfering with light transmission characteristics.
Environmental Protection
Polymeric materials are especially affected by water-laden atmospheres. Limiting water absorption is a major advantage for materials. Nanoclay and nanoparticle incorporation can reduce the extent of water absorption in polymeric nanocomposites.
Hydrophobic enhancement of polymeric materials has key benefits in terms of limiting device damage and transmittance of water to underlying substrates. Research has demonstrated that increasing nanoclay and nanoparticle aspect ratio substantially reduces water absorption.
Applications where water contact, such as marine applications, is commonplace can benefit from these enhanced properties. Additionally, water protection for commercial electronic devices such as smartphones and tablets is improved.
Innovative Nanocomposite Applications
Research into nanocomposites and how they can improve the properties of multiple conventional materials has produced innovative applications in recent years. These include graphene-enabled nanocomposites, carbon nanotube-enabled nanocomposites, and quantum dot-enabled nanocomposites.
Graphene-based nanocomposites hold huge promise in the field of renewable energy storage. They have been widely explored as electrode replacements. Intensive research into these materials has demonstrated significantly enhanced efficiency and capacity for superconductors and lithium-ion batteries.
Researchers have developed graphene and tin nanocomposites for the energy industry. These materials have been applied as high-capacity energy storage materials for lithium-ion batteries. They have a lightweight sandwich structure which enhances battery performance.
Quantum dot-enabled nanocomposites have been applied in live cell imaging in the biomedical and life science industries. An innovative approach that combines quantum dots and biodegradable hydrogel has been employed to create a delivery system for nanoparticle delivery into the cytoplasm. Cellular components can be labeled for biomedical studies using this process.
The Future
Nanocomposites have emerged as innovative materials for numerous industrial and commercial applications over the past couple of decades. Their vastly improved mechanical, physical, thermal, and barrier properties and the ability to fine-tune final material properties during preparation have piqued the interest of multiple researchers.
Innovative applications in fields such as regenerative medicine and energy storage have demonstrated the vast potential of current nanocomposite research. In the future, nanocomposites could provide potential applications such as jet wings that are stronger than currently used alloys but as light as balsa wood.
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Primary author: Professor J.N. Hay and S.J. Shaw
Source: Abstracted from “A Review of Nanocomposites 2000”
For more information please visit The Institute of Nanotechnology.
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