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The stress required to move a dislocation from one grain to another in order to plastically deform a material depends on the grain size. The average number of dislocations per grain decreases with average grain size (see Figure 3). A lower number of dislocations per grain results in a lower dislocation 'pressure' building up at grain boundaries.
The ratio of the modulus to the stiffness (a.k.a. the Foppl–von Karman number per unit area) which effectively characterizes a material's flexibility is around 570 nm −2 for the v 1/6 phase. These predicted properties are partially supported by experimental work, where v 1/6 borophene was synthesized on a surface reconstructed Ag(111 ...
The simple structure of the molecule also gives rise to surface and chemical properties that are rare in high-performance polymers. For example, the polar groups in most polymers easily bond to water. Because olefins have no such groups, UHMWPE does not absorb water readily, nor wet easily, which makes bonding it to other polymers difficult ...
Dyneema Composite Fabric (DCF), also known as Cuben Fiber (CTF3), is a high-performance non-woven composite material used in high-strength, low-weight applications. It is constructed from a thin sheet of ultra-high-molecular-weight polyethylene ( UHMWPE , "Dyneema") laminated between two sheets of polyester .
If a material contains highly directional bonds, the shear modulus will increase and give a low Poisson ratio. A material is also considered hard if it resists plastic deformation. If a material has short covalent bonds, atomic dislocations that lead to plastic deformation are less likely to occur than in materials with longer, delocalized bonds.
This is because when the grain size decreases at nm scale, there is an increase in the density of grain boundary junctions which serves as a source of crack growth or weak bonding. However, it was also observed that at grain size below 3.1 nm, a pseudo Hall–Petch relationship was observed, which results an increase in strength.
Kevlar (para-aramid) [2] is a strong, heat-resistant synthetic fiber, related to other aramids such as Nomex and Technora.Developed by Stephanie Kwolek at DuPont in 1965, [3] [2] [4] the high-strength material was first used commercially in the early 1970s as a replacement for steel in racing tires.
That is, the instantaneous fluctuations in one atom or molecule are felt both by the solvent (water) and by other molecules. Larger and heavier atoms and molecules exhibit stronger dispersion forces than smaller and lighter ones. [8] This is due to the increased polarizability of molecules with larger, more dispersed electron clouds. The ...