What is the Continuous Phase in Composites
Nanocomposites
József Hári , Béla Pukánszky , in Applied Plastics Engineering Handbook, 2011
8.8 Conclusions
Nanocomposites are heterogeneous materials—thus their properties are determined by the same factors as in traditional composites, i.e., component properties, composition, structure, and interfacial interactions. On the other hand, their structure is usually more complicated than that of microcomposites, and that is especially valid for polymer/layered silicate nanocomposites. Besides the usually assumed individual silicate platelets and tactoids, layered silicate nanocomposites may contain also large particles and a silicate network can also form in them at large extent of exfoliation. Aggregation and orientation are the most important structural phenomena in CNT-reinforced composites, and aggregation dominates also in composites prepared with spherical particles. Interfacial interactions should play an increased role in nanocomposites compared to traditional composites because of the assumedly very large interfacial area developing in them. Surprisingly, the surface characteristics of nanofillers are rarely determined or known. The surface of these reinforcements is modified practically always. The goal of the modification is to improve dispersion and/or adhesion in CNT- and spherical particle-reinforced composites and to help exfoliation in layered silicate nanocomposites. Unfortunately, modification decreases surface energy in the latter case leading to decreased interaction with the matrix. Very limited information exists about interphase formation and the properties of the interphase in nanocomposites, although they might influence properties considerably. All kinds of nanocomposites can be prepared with in situ polymerization, solvent-assisted methods, and melt homogenization. Because of its practical relevance, the latter technique is used most frequently, but dispersion and homogeneity are major issues in all three technologies. The properties of nanocomposites are usually far from the expectations, the main reason being insufficient homogeneity, lack of sufficient orientation, and improper adhesion. In spite of considerable difficulties nanocomposites have great potentials especially in specific, niche applications. Several nanocomposite products are already used in industrial practice.
Read full chapter
URL:
https://www.sciencedirect.com/science/article/pii/B978143773514710008X
Nanocomposites
Rajesh Mishra , Jiri Militky , in Nanotechnology in Textiles, 2019
6.2.6 Hybrid nanocomposite particles
Hybrid nanocomposites based on Ag and Au nanoparticles and chitosan (CS) in form of films with high antibacterial activity and retained cytotoxicity against eukaryotic cells have been recently investigated. In terms of the potential biomedical application, since Ag and Au nanoparticles are entrapped in the solid polymeric matrix, these bioactive materials prevent the availability of NPs for eukaryotic cells while preserving the pronounced antimicrobial activity against selected resistant biofilm-forming strains (i.e., Staphylococcus aureus, Pseudomonas aeruginosa, E. coli, or Candida albicans). Bacterial cell wall morphology studies upon incubation with medium molecular weight (MW) chitosan-based nanocomposites confirmed that for the tested bacterial strains, significant and progressive damage on the cell wall was observed, which resulted in a total cell lysis. The examples of demonstrated biocidal activity of Ag and AuNP-based composites are investigated in detail. It is suggested that the lack of significant cytotoxicity against mammalian cells is a consequence of biocompatible chitosan layer surrounding the surface of metal NPs. Due to the presence of chemical bonds between NPs and chitosan, the potential direct interactions of bare nanoparticles with cellular components are diminished. In the case of the resulting nanomaterials, the main bactericidal effect is mainly a result of the Ag and AuNP activity. Certainly, since the positive charge of the polymer is reduced during NP synthesis and further film formation, the antibacterial activity of chitosan films decreases in comparison with the polymeric dispersion; however, bacteriostatic activity of the pure polymer is still observed [18].
In recent years, infections caused by multidrug-resistant (MDR) microbes have become a global health challenge. To stop the spread of drug-resistant infections, several parallel actions seem to be urgent and imperative including development of new rapid diagnostic systems to cut the unfounded use of antibiotics, fundamental changes in prescriptions and consumption of existing antibiotics to preserve their usefulness, applying combination therapies, and the development of effective alternative approaches in antimicrobial drugs discovery. Recently, bioinorganic platforms like metal complexes, metal-modified macromolecules, and metal oxide nanoparticles have become attractive alternatives to combat microbes that are resistant to various classes of antibiotics. The vast array of physicochemical properties of these platforms enables them to act as antimicrobial agents through various mechanisms. They can also serve as carriers for drugs delivery. Moreover, combination of bioinorganic platforms and light offers very promising alternative antimicrobial strategies like photothermal therapy or photodynamic microorganism inactivation. Unique electronic, structural, spectroscopic properties and redox or acid-based thermal or photochemical reactivity make bioinorganic platforms appropriate to provide innovative antimicrobial strategies with simultaneous prevention of resistance development and protection of the natural host microbiome [19,20].
Read full chapter
URL:
https://www.sciencedirect.com/science/article/pii/B9780081026090000067
Nanocomposites
Donglu Shi , ... Nicholas Bedford , in Nanomaterials and Devices, 2015
11.2.4 Implementation of Nanoparticle Modification
Means for the implementation of modifying nanoparticles can be divided into mechanical dispersion, ultrasonic dispersion, and high-energy processing methods. Mechanical force dispersion mainly uses mechanical effects by external shearing force or impact force, and the special surface structure of nanoparticles is prone to chemical reactions, so that nanoparticles may undergo chemical changes with the surrounding medium (e.g., the surrounding solid, liquid, or gas) to form a layer of branched-chain organic compounds or a protection layer on its surface to make it easier for the dispersion of nanoparticles. Fe3O4 powder and micron polyvinyl chloride (PVC), when dispersed in high-energy ball milling, are able to form α-Fe3O4 /PVC nanocomposites, where α-Fe 3O4 may have a particle size of 10 nm. Ultrasound is widely used in chemistry, playing an important role in the synthesis of compounds, polymer degradation, and the dispersion of particulate matter. When nano-CrSi2 particles (with an average diameter of 10 nm) are added to tetrahydrofuran solution containing acrylonitrile–styrene copolymer via ultrasonic dispersion, nanocrystals may become available for coating the polymer materials. The high--energy approach indicates the use of ultraviolet, infrared, corona discharge, and the plasma radiation method to perform the surface modification of nanoparticles. In addition, methyl methacrylate can be grafted onto nano-MgO with the help of UV radiation. Such surface modification can greatly improve the dispersion of nanopowder in high-density polyethylene (PE).
Plasma is a system comprising a large number of charged particles (ions, electrons) from ionized gas and the neutral particles in excited states (atoms, molecules). The system contains the same total number of positively and negatively charged particles. Over the past 20 years, plasma technology has made fruitful achievements in the fields of chemical synthesis, new materials development, fine chemicals, and surface treatment. In recent years, there have been more reports on studies and research on using plasma technology for surface modification of nanoparticles for biomedical purposes [5]. Plasma technology is relatively low cost, easy to operate, and useful to control material modification by optimizing process conditions. In theory, it can achieve the surface modification of the materials of any nature in any shape without changing the physical properties of the nanomaterial.
There are two main types of reactions between plasma and the material surface, namely plasma polymerization and plasma surface treatment. By way of plasma polymerization, organic monomer can be converted into a plasma state to produce various active species (free radicals) for surface polymerization. Plasma surface treatment involves the use of energy particles and reactive species in the plasma of nonconvergent gas (e.g., argon, nitrogen, oxygen) to react with the surface of the material to be processed, resulting in the surface producing a particular functional group (e.g., –OH, –N2H). These two types of reactions can change the surface composition and structure, aiming to achieve the purpose of material surface modification.
With the development of medical research, a variety of transplant technologies for therapeutic, diagnostic, and orthopedic surgeries were developed, and the implants had to satisfy many requirements, such as biocompatibility, permeability, anti-aging and nontoxic properties, and so on. Many polymer materials usually have satisfactory mechanical properties such as bulk properties, but they cannot be used as implants because their surface properties often fail to meet these requirements. Over the years, many domestic and foreign researchers have been trying to introduce a variety of physical, chemical, or biological means to perform surface modification on biological materials. Plasma technology has been proven to be a very effective approach.
Read full chapter
URL:
https://www.sciencedirect.com/science/article/pii/B9781455777549000111
Nanocomposites for improved orthopedic and bone tissue engineering applications
M. Saquib Hasnain , Amit Kumar Nayak , in Applications of Nanocomposite Materials in Orthopedics, 2019
7.2 Biomedical nanocomposites
Nanocomposites designed for various biomedical purposes, which are often called "biomedical nanocomposites." There are numerous prospective biomedical nanocomposites, which can be classified into various overlapping categories. The most important biomedical uses of these biomedical nanocomposites comprise drug delivery, antimicrobial properties, tissue engineering, wound dressings, stem cell therapy, cancer therapy, cardiac prosthesis, artificial blood vessels, biosensors, and enzyme immobilization [28,29]. Various applications of biomedical nanocomposites are summarized in Table 7.1. Four important advanced applications of biomedical nanocomposites are illustrated in Fig. 7.1.
Table 7.1. Various applications of biomedical nanocomposites
| Applications | Biomedical nanocomposites/nanocomposite-based systems | References |
|---|---|---|
| Drug delivery | Nanocomposites of cassava starch acetate-PEG/gelatin | [30] |
| Chitosan-starch nanocomposite particles | [31] | |
| Pectin microspheres-CaPO4 composite bone cement | [32] | |
| MMT-alginate nanocomposite | [33] | |
| Alginate-PVP-nano-HAp composite matrices | [34] | |
| Chitosan-sodium alginate nanocomposites | [35] | |
| Melt-blended halloysite nanotubes/wheat starch nanocomposites | [36] | |
| Chitosan-clay nanocomposite microparticles | [37] | |
| Sodium alginate/nano-HAp nanocomposite beads | [38] | |
| Modified K-carrageenan nanocomposite hydrogels | [39] | |
| Nano-HAp-antibiotic composites | [40–44] | |
| Stem cell therapy | Chemically modified bacterial cellulose nanocomposite | [45] |
| Cardiac prosthesis | Modified polyhedral oligomeric silsesquioxane-nanocomposite | [46] |
| PVA-bacterial cellulose nanocomposite | [47] | |
| Artificial blood vessels | Nanocrystalline cellulose-fibrin nanocomposites | [48] |
| Tissue engineering | Bacterial cellulose/HAp nanocomposite scaffolds | [49] |
| a-chitin/nanobioactive glass ceramic composite | [50] | |
| Bacterial cellulose/heparin hybrid nanofiber composites | [51] | |
| First otoliths/collagen/bacterial cellulose nanocomposites | [52] | |
| Porous K-carrageenan/CaPO4 nanocomposite scaffolds | [53] | |
| Chitosan-PVP-TiO2 nanocomposite | [54] | |
| Wound dressings | Chitosan-pectin-TiO2 nanocomposite film | [55] |
| Banana peel powder/chitosan nanocomposites | [56] | |
| Nano-Ag/ b-chitin composite scaffolds | [57] | |
| MMT-chitosan-silver sulfadiazine nanocomposites | [58] | |
| Alginate/Ag/nicotinamide nanocomposites | [59] | |
| Bacterial cellulose-ZnO nanocomposites | [60] | |
| Sodium alginate/PVA/nano-ZnO composite nanofibers | [61] | |
| Antimicrobial properties | Chitosan-Ag/PVP nanocomposite films | [62] |
| HAp/Ti nanocomposites | [63] | |
| Zn-mineralized alginate nanocomposites | [64] | |
| Grafted sugarcane bagasse/Ag nanocomposites | [65] | |
| Fe3O4-HAp nanocomposites | [66] | |
| Cancer therapy | Polypyrrole-poly (3, 4 ethylene dioxy thiophene)-Ag nanocomposite films | [67] |
| Biosensors | Polypyrrole polyaniline-Au nanocomposite films | [68] |
| Electromagnetic poly(p-phenylene diamine) @Fe3O4 nanocomposite | [69] | |
| Graphene/PVP/polyaniline nanocomposite | [70] | |
| Graphene-polyaniline nanocomposite | [71] | |
| Polyaniline‑bismuth oxide nanocomposite | [72] |
Fig. 7.1. Four important applications of biomedical nanocomposites: (A). quenching of heparin-labeled with fluorescent when bound to gold nanoparticles and releasing via heparanase quenching to decrease the allowing of heparinase generating cancer cells' recognition; (B) zinc-oxide nanoparticles developed on the cellulose fibers transducing mechanical as well as thermal energies to electrical energy; (C) doxorubicin (an anticancer drug) circulating via blood vessels passed through an extracorporeal cartridge containing activated carbon particles coated with a nanoporous PMMA/chitosan/heparin nanocomposite film to release doxorubicin; (D) heparin coupled with gelatin-lining matrix containing CaPO4 employing to release BMP-2 to support the cell differentiation.
From Y. Zheng, J. Monty, R. J. Linhardt, Polysaccharide-based nanocomposites and their applications, Carbohydr. Res. 405 (2015) 23–32; Copyright © 2014 Elsevier Ltd.Read full chapter
URL:
https://www.sciencedirect.com/science/article/pii/B9780128137406000089
Sensing Materials: Nanocomposites
Ayesha Kausar , in Reference Module in Biomedical Sciences, 2021
Abstract
Nanocomposites have been considered as valuable podia for the development of sensors. Among nanocomposites, polymeric nanocomposites have caused significant breakthroughs in the field of sensing technology. The polymer-based nanocomposites have been successfully employed for sensor formation. In this regard, conducting polymers, thermoplastic, and elastomeric polymers have been used. Nanocarbons and inorganic nanoparticles (metal nanoparticles and metal oxides) have been used with the polymer matrices to develop the sensors. The sensing properties and performance visibly depend on the interaction between the nanocomposites and the analyte species such as gases, chemicals, ions, biological species and other response conditions. The nanocomposites-based sensors have superior sensitivity, electrical conductivity, selectivity, response, and performance relative to neat polymers and other nanomaterials. Specifically, nanocomposites' applications have been verified for biosensing, chemical sensing, strain sensing, and gas sensing.
Read full chapter
URL:
https://www.sciencedirect.com/science/article/pii/B9780128225486000480
INTRODUCTION TO POLYMERS FOR ELECTRONIC ENGINEERS
Sulaiman Khalifeh , in Polymers in Organic Electronics, 2020
1.9.5 ELECTRONIC NANOCOMPOSITES
Nanocomposites are the polymers containing nanoparticles of dimensions less than 100 nm. Nanocomposites can be classified as metal-matrix, ceramic-matrix, and polymer-matrix. Polymer-matrix nanocomposites can be synthesized in the form of electrically conductive nanocomposites for forming nanocomposite films used for nanoelectronic systems. Carbon nanotubes CNTs nanocomposites have high electrical conductivity due to their high aspect ratio. 39, 40 Examples of nanomaterials include silica nanoparticles, silsesquioxanes, carbon nanotubes, and layered silicates; and examples of polymer-matrix nanocomposites include commercial polyimide-6 such as nylon®6 grade, 43, 44 polymethylmethacrylate nano-composites, and polystyrene nano-composites used for the fabrication of light optical fibers LOF and polymer (organic) optical fibers. Electronic nanocomposites 88 are carbon nanotube-based with excellent thermal, electrical, and mechanical properties; so that they can be used for specific electronic systems such as those structured of high thermal conducting interface materials for the purpose of heat dissipation. In this case, polymers act as hosts such as the conducting polymer called poly(3,4-ethylenedioxy-thiophene) PEDOT with thermal conductivity ranging from 3000-6600 W/mK.
Read full chapter
URL:
https://www.sciencedirect.com/science/article/pii/B9781927885673500067
Volume 1
Kaivalya A. Deo , ... Akhilesh K. Gaharwar , in Encyclopedia of Tissue Engineering and Regenerative Medicine, 2019
Conclusion
Nanocomposite hydrogels show potential to be used in variety of different biomedical applications such as tissue engineering, therapeutic delivery, stem cell modulation and medical devices. These different biomedical and biotechnological applications are possible due to tunable nature of the nanocomposite hydrogels. The improved properties of the nanocomposite hydrogels are mainly attributed to enhanced interactions between the polymer chains and the nanomaterials. Next generation of nanocomposite hydrogels will not only enhance mechanical and physical properties but will be able to deliver special bioactive cues which would make them more responsive and adaptable to the environment in which they would be utilized.
Read full chapter
URL:
https://www.sciencedirect.com/science/article/pii/B9780128012383111146
Polymer Composites
Joseph P. Greene , in Automotive Plastics and Composites, 2021
12.5 Nanocomposite
Nanocomposite is a multiphase solid material where the reinforcement from clay has one, two, or three dimensions of less than 100 nanometers (nm). For plastics, the nanocomposites are made from Montmorillonite clay. The size of clay is on a pico (10− 9) meter scale that causes swelling due to exfoliation in the plastic and results in increased strength and stiffness at a concentration less than with glass fibers. Nanocomposites are typically added in a concentration of 2%–10%. Glass and mineral fibers are usually added in concentrations of 10%–40%. An example of a nanocomposite is shown in Fig. 12.7.
Fig. 12.7. Nanocomposite example (Gacitua et al., 2005).
Nanocomposites provide high strength and stiffness at lower concentrations than glass fiber. They can be used for many automotive parts including engine covers, timing belt covers, and body trim pieces. The nanocomposites typically are 0.5 μm in size. The nanoparticle can be 50,000 smaller than the plastic component. The properties of a nanocomposite particle with nylon is presented in Table 12.3.
Table 12.3. Mechanical properties in-reactor polymerization (Han et al., 2017).
| Material | Nanomer I.24T% (wt/wt) | FlexStr | FlexMod | TenStr | TenMod | [email protected] 264 psi |
|---|---|---|---|---|---|---|
| (MPa) | (MPa) | (MPa) | (MPa) | |||
| Nylon 6 (Control) | 0 | 107 | 2885 | 72 | 1821 | 55 |
| Nanocomposite | 2.5 | 144 | 3644 | 91 | 2372 | 112 |
Read full chapter
URL:
https://www.sciencedirect.com/science/article/pii/B9780128180082000076
Nanotechnology and green materials: Introduction, fundamentals, and applications
N. Madima , ... A.K. Mishra , in Green Functionalized Nanomaterials for Environmental Applications, 2022
1.2.3 Nanocomposites
Nanocomposites are poly-phase solid materials made up of two or more nanomaterials. Those solid materials are made up of several phases, with one phase having its dimensions in nanoscale. They display high surface-area-to-volume ratio characteristics. They usually incorporate nanoparticles into a matrix of standard materials to enhance their properties such as toughness, electrical or thermal conductivity, and mechanical strength ( Saleh, 2020). Nanocomposites are divided into three groups depending on their matrix materials (Schaefer and Justice, 2007; Omanovi et al., 2020):
- •
-
Ceramic matrix nanocomposites (CMNC): these are nanocomposites in which one or more ceramic phases are mixed to enhance properties such as resistance, thermal stability, and chemical stability. Examples of CMNC include nanocomposite of SiO2/Fe, SiO2/Ni, and PbTiO3/PbZrO3 among others. They have been widely applied in catalysis, data storage, electronics, and chemical sensors.
- •
-
Polymer matrix nanocomposites (PMNC): these are usually nanocomposites in which the polymer matrix is mixed with nanofillers. Nanofillers can be linear, layered, or powder. These nanocomposites display characteristics such as high thermal stability, enhanced mechanical properties, and lower gas permeability. Due to their interesting properties, they have received significant attention in various filed such as energy storage, packaging, and power tool housing.
- •
-
Metal matrix nanocomposites (MMNC): these are multiphase materials made up of metal or alloy matrix in which other nanosized supplementing materials are embedded. Example of MMCN includes nanocomposites such as Fe/MgO, Cu/Al2O3, Cu/ZrN, and Nb/Cu among others. They display characteristics such as hardness, high ductility, high modulus, and high strength. They have been widely applied in the aerospace or automotive industry.
Over the past decades, a variety of nanomaterials has been discovered and applied in various applications, and they have paved the way into the future. The upcoming section highlights the synthesis of nanomaterials for various applications using a green synthesis approach.
Read full chapter
URL:
https://www.sciencedirect.com/science/article/pii/B9780128231371000014
Introduction and reinforcing potential of silica and various clay dispersed nanocomposites
Md. Rezaur Rahman , ... Sinin bin Hamdan , in Silica and Clay Dispersed Polymer Nanocomposites, 2018
1.5.3 Structure of nanocomposites
A nanocomposite is defined as a composite material in which at least one dimension of the component is in the nanometer size scale (< 100 nm). The three different types of nanocomposites morphologies that are generally obtained include phase separated systems, intercalated systems, and exfoliated systems. Different systems are formed due to the nature of the components (clay and polymer matrix) and preparation methods (Camargo, Satyanarayana, & Wypych, 2009).
Phase separated nanocomposites are obtained when the polymer is unable to intercalate between the silicate sheets, whose properties stay in the same range as that of traditional microcomposites due to the hydroxylated edge-edge interaction (Mallikarjuna, 2009). Thus, the d-spacing of clay will not change and cause the nanocomposites to have poor mechanical properties. For intercalated nanocomposites, the polymer chains are inserted in the interlayer gallery. Which increases the interlayer distance. This leads to the formation of a well ordered multilayered morphology, with alternating polymeric and inorganic layers (Olad, 2011). The mechanical and thermal properties of intercalated nanocomposites are significantly improved compared to phase separated nanocomposites (Chow, 2008). Exfoliated nanocomposites are also referred to as delaminated nanocomposites. The individual clay layers are separated and uniformly distributed in a continuous polymer matrix (Alexandre & Dubois, 2000). Overall, intercalated nanocomposites exhibit better homogeneity than exfoliated nanocomposites (Chen, 2004).
Read full chapter
URL:
https://www.sciencedirect.com/science/article/pii/B9780081021293000014
Source: https://www.sciencedirect.com/topics/engineering/nanocomposite
0 Response to "What is the Continuous Phase in Composites"
Post a Comment