Recent developments in RAM based MWCNT composite materials: a short review

Abstract

The need of developing Radar absorbing materials which meet the structural requirement of Defense applications is growing swiftly due to extensive use of electromagnetic (EM) waves in Radars. With major development and extensive use of Radar in military applications, the role of Radar absorbing structures with light weight and high strength has become prime objective for researcher working on development of Radar absorbing materials. Various composites are developed by using reinforcements which are dielectric such as CNT, Magnetic materials like Ferrites, have been extensively used as reinforcement in developing Radar absorbing materials. The ferromagnetic materials have high density and can achieve only narrow bandwidth absorption, CNT have very good electrical, mechanical and thermal properties and can achieve high dielectric losses but its complex synthesis process is a barrier in commercial applications. The research of reinforcing MWCNT with ferrites and metal oxides can also be extend to study thermoplastic polymers like PEEK and PAEK which is gaining prominence in aeronautical applications owing to its superior mechanical and low moisture absorbing properties. Further research can be done on the reinforcing metal oxides as metal oxides when reinforced with MWCNT proved to enhance the dielectric properties which improved the reflection losses as reported in a few studies.

Effects of Elevated Temperature on the Residual Behavior of Concrete Containing Marble Dust and Foundry Sand

“…Figure 11 shows the static modulus of elasticity of the control mix and concrete containing marble dust and foundry sand subjected to increased temperatures of 200 °C, 400 °C, 600 °C, 800 °C, and 1000 °C. The static modulus of elasticity was measured to see how the deformation capacity of the concrete mixtures changed over time [ 17 , 28 , 35 , 39 , 94 , 95 , 96 , 97 , 98 ]. In all cases of concrete exposed to high temperatures, the static modulus of elasticity was shown to be reduced.…”

“…Figure 12 shows the dynamic modulus of elasticity of the control mix and concrete containing marble dust and foundry sand subjected to increased temperatures of 200 °C, 400 °C, 600 °C, 800 °C, and 1000 °C. Elevated temperature causes considerable damage to the cement matrix, according to the dynamic modulus of elasticity [ 17 , 28 , 35 , 39 , 94 , 95 , 96 , 97 , 98 , 99 , 100 , 101 , 102 ]. In all cases of concrete exposed to extreme temperatures ranging from 200 °C to 1000 °C, the dynamic modulus of elasticity was shown to be reduced.…”

“…However, at higher temperatures (1000 °C), it increased by approximately three times, indicating fast degradation in all mixtures. This is owing to the development of large voids in both mixtures due to the dehydration of the C-S-H gel [ 17 , 28 , 35 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 88 , 89 , 97 , 98 , 99 , 100 , 101 , 102 , 103 ]. Due to the differences in water absorption of the two distinct materials, concrete mixes comprising marble dust and foundry sand absorb less water than control mixes.…”

Investigation on Carbonation and Permeability of Concrete with Rice Hush Ash and Shop Solution Addition

“…From the permeability result, it is also found that coefficient of permeability with 2 percent soap solution is very much less in comparison with 0 percent soap solution. From the observation of SEM images, it can be said that soap solution helps in filling the voids of concrete which ultimately helps in reduction in permeability [ 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 ]. EDX analyses of concrete with 0% (M1) and 2 % (M6) soap solution are shown in Figure 9 and Figure 10 respectively.…”

Critical Review on Polylactic Acid: Properties, Structure, Processing, Biocomposites, and Nanocomposites

“…To improve the flexibility and toughness of PLA, plasticizing is performed with its own monomer [257]. This plasticized PLA possesses mechanical and physical properties comparable to synthetic polymers, viz., polypropylene, polyvinyl chloride, and polystyrene, thus expanding the scope of PLA as a series of flexible and tough products [258]. However, exceeding the plasticizer content beyond 20% in the composition may lead to the separation of phases in a part or whole of the body.…”