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Topic Review
Acoustic Metamaterials in Aeronautics
Metamaterials, man-made composites that are scaled smaller than the wavelength, have demonstrated a huge potential for application in acoustics, allowing the production of sub-wavelength acoustic absorbers, acoustic invisibility, perfect acoustic mirrors and acoustic lenses for hyper focusing, and acoustic illusions and enabling new degrees of freedom in the control of the acoustic field. The zero, or even negative, refractive sound index of metamaterials offers possibilities for the control of acoustic patterns and sound at sub-wavelength scales. The potential of metamaterial-based technologies has recently caught the interest of the aeronautics community. Their effect in the presence of realistic flows in the surrounding domains, with boundary layer, turbulence, is currently a hot research topic. The interaction with flow requires a careful design of the metamaterial to avoid detrimental effects and enabling the device maximum capabilities in aeronautics.
  • 1.9K
  • 25 Jun 2021
Topic Review
Glass Crystalline Materials
Glass crystalline materials (GCM) are composite solids consisting of both vitreous and crystalline phases. The major component can be the crystalline phase with a vitreous phase acting as a binding agent or alternatively the vitreous phase can be the major component, with crystalline particles dispersed in the glass matrix. 
  • 1.9K
  • 27 Apr 2021
Topic Review
Hybrid Reinforced Polymer Matrix Composites
The use of composite materials has seen many new innovations for a large variety of applications. The area of reinforcement in composites is also rapidly evolving with many new discoveries, including the use of hybrid fibers, sustainable materials, and nanocellulose.
  • 1.8K
  • 22 Feb 2023
Topic Review
Fiber Metal Laminates
Composite materials such as Fibre Metal Laminates (FMLs) have attracted the interest of the aerospace and automotive industries due to their high strength to weight ratio, but to use them as structures it is necessary to master the manufacturing and wiring techniques of these materials. The process parameters used in multi-material machining, such as drilling and milling, tool geometry, tool coating, lubricants and coolants, must be well established to achieve a successful machining process in FLM materials. Failure of any of these parameters can cause irreparable damage to the material, wasting the process and making it less sustainable. Understanding the failure process is essential to improve the accuracy of the analysis, to supplement the information and to provide a deterrent to adjusting process parameters.
  • 1.8K
  • 19 Apr 2023
Topic Review
In Situ Polymerization for Composites
Due to the extremely low viscosity of the cyclic lactams and the superior mechanical properties of the polymers obtained from them, these materials have great potential for application in different liquid composite molding (LCM) techniques. Unsurprisingly, extensive academic research has been conducted over the past years to investigate possible industrial applications of anionically polymerized thermoplastic composites (TPCs) reinforced with glass, carbon, aramid, or natural fibers. It is important to remember that enormous progress has been made in the development of machinery and materials. There are different types of reactive processes for obtaining Nylon-6 composites; some of the main technologies are presented.
  • 1.8K
  • 19 May 2022
Topic Review
Bifacial Photovoltaics
In 2016 the first >2 MWp fixed tilt bifacial PV system (“La Hormiga”) was built by MegaCell in San Felipe, located in the region of Valparaiso in Chile, using nPERT BiSoN modules. The innovations in this system were the adapted mounting structures (which were not covering the rear side of the modules), as well as the enhancement of albedo using white quartz stones below them. The bifacial gain was about 15% with the natural albedo of ca. 28%, whereas the albedo enhancement to 75% provided by the white stones led to a bifacial gain of about 25%. After that, Sunpreme installed their SHJ (Silicon HeteroJunction) modules in a 10 MWp bifacial system on a US industrial rooftop, and large bifacial systems were installed in China in the TopRunner program, where the Chinese Government was supporting innovations to be introduced into the market. Yingli installed a fixed tilt 50 MWp system with bifacial nPERT Panda modules, followed by a 100 MWp “Panda PV system” in 2018. Since then large bifacial PV systems are entering the PV market. In 2021 bifacial PV became bankable and will become main-stream in the coming 5 years.
  • 1.8K
  • 08 May 2021
Topic Review
Poly(Ionic Liquid) Materials-Based Advanced Formulations for Additive Manufacturing
Innovation in materials specially formulated for additive manufacturing is of great interest and can generate new opportunities for designing cost-effective smart materials for next-generation devices and engineering applications. Nevertheless, advanced molecular and nanostructured systems are frequently not possible to integrate into 3D printable materials, thus limiting their technological transferability. In some cases, this challenge can be overcome using polymeric macromolecules of ionic nature, such as polymeric ionic liquids (PILs). Due to their tuneability, wide variety in molecular composition, and macromolecular architecture, they show a remarkable ability to stabilize molecular and nanostructured materials. The technology resulting from 3D-printable PIL-based formulations represents an untapped array of potential applications, including optoelectronic, antimicrobial, catalysis, photoactive, conductive, and redox applications.
  • 1.8K
  • 08 Dec 2022
Topic Review
Fire-Safe Polymer Composites
Currently, polymers are competing with metals and ceramics to realize various material characteristics, including mechanical and electrical properties. Flame retardants can also be introduced to further reinforce the fire performance of polymers.
  • 1.8K
  • 09 Apr 2021
Topic Review
Global Plastic Waste is Increasing
Global plastic waste is increasing rapidly. In general, densely populated regions generate tons of plastic waste daily, which is sometimes disposed of on land or diverged to sea. Most of the plastics created in the form of waste have complex degradation behavior and are non-biodegradable by nature. These remain intact in the environment for a long time span and potentially originate complications within terrestrial and marine life ecosystems. The strategic management of plastic waste and recycling can preserve environmental species and associated costs. 
  • 1.8K
  • 24 Sep 2021
Topic Review
Thermosets with Flame Retardants
Epoxy and unsaturated polyester resins are the most used thermosetting polymers.They are commonly used in electronics, construction, marine, automotive and aircraft industries.Moreover, reinforcing both epoxy and unsaturated polyester resins with carbon or glass fibre in a fabric form has enabled them to be used in high-performance applications. However, their organic nature as any other polymeric materials made them highly lammable materials. Enhancing the flame retardancy performance of thermosetting polymers and their composites can be improved by the addition of flame-retardant materials, but this comes at the expense of their mechanical properties. In this regard, a comprehensive review on the recent research articles that studied the flame retardancy of epoxy resin, unsaturated polyester resin and their composites were covered. Flame retardancy performance of different flame retardant/polymer systems was evaluated in terms of Flame Retardancy index (FRI) that was calculated based on the data extracted from the cone calorimeter test. Furthermore, lame retardant selection charts that relate between the flame retardancy level with mechanical properties in the aspects of tensile and lexural strength were presented. This review paper is also dedicated to providing the reader with a brief overview on the combustion mechanism of polymeric materials, their flammability behaviour and the commonly used flammability testing techniques and the mechanism of action of flame retardants.
  • 1.8K
  • 29 Mar 2021
Topic Review
Panel Products Made of Oil Palm Trunk
Oil palm plantations have expanded rapidly in Southeast Asia, particularly in Indonesia and Malaysia. A lot of products, including food and other edible products, oleo-chemicals, cosmetics, personal and household care, pharmaceutical products, and biodiesels are derived from palm oil, thus making them one of the most economically important plants.
  • 1.7K
  • 17 May 2022
Topic Review
Polymer-Matrix Composites - Environmental Fatigue, Creep, Long-Term Durability
Polymer-matrix composites are widely used in engineering applications. Yet, environmental factors impact their macroscale fatigue and creep performances significantly, owing to several mechanisms acting at the microstructure level. Seawater, due to a combination of high salinity and pressures, low temperature and biotic media present, also contributes to the acceleration of fatigue and creep damage. Similarly, other liquid corrosive agents penetrate into cracks induced by cyclic loading and cause dissolution of the resin and breakage of interfacial bonds. UV radiation either increases the crosslinking density or scissions chains, embrittling the surface layer of a given matrix. Temperature cycles close to the glass transition damage the fibre–matrix interface, promoting microcracking and hindering fatigue and creep performance. The microbial and enzymatic degradation of biopolymers is also studied, with the former responsible for metabolising specific matrices and changing their microstructure and/or chemical composition. 
  • 1.7K
  • 07 Jul 2023
Topic Review
Red-Beetroot-Extract in the Biodegradable Polymers
This study investigated the effect of natural antioxidants inherent to beetroot (Beta vulgaris var. Vulgaris) on the ageing of environmentally friendly plastics. Certain properties were examined in this context, comprising thermal, mechanical, and morphological properties. A visual evaluation of relevant changes in the given polymers (polylactide and polycaprolactone) was conducted during an ageing test in a UV chamber (45 °C, 70% humidity) for 720 h. The films were prepared by a casting process, in which samples with the extract of beetroot were additionally incorporated in a common filler (bentonite), this serving as a carrier for the extract. The results showed the effect of the incorporated antioxidant, which was added to stabilize the biodegradable films. Its efficiency during the ageing test in the polymers tended to exceed or be comparable to that of the reference sample. 
  • 1.7K
  • 04 Sep 2021
Topic Review
Nanotechnology and Biodegradable Biopolymer-Based Packaging Materials
There is great interest in developing biodegradable biopolymer-based packaging materials whose functional performance is enhanced by incorporating active compounds into them, such as light blockers, plasticizers, crosslinkers, diffusion blockers, antimicrobials, antioxidants, and sensors. However, many of these compounds are volatile, chemically unstable, water-insoluble, matrix incompatible, or have adverse effects on film properties, which makes them difficult to directly incorporate into the packaging materials. These challenges can often be overcome by encapsulating the active compounds within food-grade nanoparticles, which are then introduced into the packaging materials. The presence of these nanoencapsulated active compounds in biopolymer-based coatings or films can greatly improve their functional performance. For example, anthocyanins can be used as light-blockers to retard oxidation reactions, or they can be used as pH/gas/temperature sensors to produce smart indicators to monitor the freshness of packaged foods. Encapsulated botanical extracts (like essential oils) can be used to increase the shelf life of foods due to their antimicrobial and antioxidant activities. The resistance of packaging materials to external factors can be improved by incorporating plasticizers (glycerol, sorbitol), crosslinkers (glutaraldehyde, tannic acid), and fillers (nanoparticles or nanofibers). Nanoenabled delivery systems can also be designed to control the release of active ingredients (such as antimicrobials or antioxidants) into the packaged food over time, which may extend their efficacy.
  • 1.6K
  • 22 Dec 2021
Topic Review
Waste Rubber Particles
One of the environmental problems causing concern in the world today is the black pollution caused by the accumulation of waste rubber resources. Rubber concrete can help solve the black pollution problem caused by waste rubber tires, but it is undeniable that rubber particles will reduce the mechanical properties of concrete. Research on waste rubber particles, particle size and properties are needed for the modification of rubberized concrete.
  • 1.6K
  • 22 Jul 2022
Topic Review
Nanocellulose from Agricultural Wastes
Nanocellulose-based composites are characterized for being highly biocompatible and scarcely toxic, which are the the major reasons for its use in numerous biomedical applications. Incorporation of nanocellulose to drug delivery systems could control both the manner drugs are released and the interactions with target molecules, thus increasing the effectiveness of drug administration. Changes on nanocellulose surface must be carried out to link drugs, non-ionic chemicals with hydrophobic character, to the nanopolymer.
  • 1.6K
  • 18 Sep 2021
Topic Review
Synthesis of Porous Composite Metal Oxides
Porous transition-metal oxides with good intrinsic activities can be used to disperse and stabilize the active noble metal phases, thus promoting improvements in selectivity and activity of the supported noble metal catalysts and in the meanwhile reinforcing the optimized utilization of noble metals.
  • 1.6K
  • 27 Feb 2023
Topic Review
Types of Hybrid Bio-Based Aerogel Materials
Bio-based aerogels are derived from various renewable sources such as sugar cane, vegetable oils, proteins, starches, chitosan, alginate, pectin, lignin, cellulose, and proteins, which have been shown to be useful in the production of aerogels. These aerogels have special properties that make them well suited for packaging applications and in bioengineering. Studies in this field have led to advances that shed light on their diverse applications, improved properties, and innovative synthesis methods. Researchers have investigated alternative feedstocks for bio-based aerogels to broaden their sources and enhance sustainability. Studies have explored the use of waste materials, agricultural by-products, and unconventional sources to synthesize aerogels, aligning with the principles of a circular and green economy. 
  • 1.6K
  • 04 Jan 2024
Topic Review
Fabric/Fiber-Based Triboelectric Nanogenerators
Triboelectric nanogenerator (TENG), as a green energy harvesting technology, has aroused tremendous interest across many fields, such as wearable electronics, implanted electronic devices, and human-machine interfaces. Fabric and fiber-structured materials are excellent candidates for TENG materials due to their inherent flexibility, low cost, and high wearing comfort. Consequently, it is crucial to combine TENG with fabric/fiber materials to simultaneously leverage their mechanical energy harvesting and wearability advantages.
  • 1.6K
  • 17 Aug 2022
Topic Review
Low/Medium-Carbon Advanced Martensitic Steels
Advanced martensitic steels (AMSs) developed for sheet and wire rod products have a tensile strength higher than 1.5 GPa, good cold-formability, superior toughness and fatigue strength, and delayed fracture strength due to a mixture of martensite and retained austenite, compared with the conventional martensitic steels. 
  • 1.6K
  • 09 Oct 2021
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