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Liquid-crystal polymers are present in melted/liquid or solid form. [7] In solid form, the main example of lyotropic LCPs is the commercial aramid known as Kevlar . The chemical structure of this aramid consists of linearly substituted aromatic rings linked by amide groups.
Kevlar is used to manufacture gloves, sleeves, jackets, chaps and other articles of clothing [27] designed to protect users from cuts, abrasions and heat. Kevlar-based protective gear is often considerably lighter and thinner than equivalent gear made of more traditional materials. [26] Kevlar is a very popular material for racing canoes.
The strong bonding of metals in liquid form demonstrates that the energy of a metallic bond is not highly dependent on the direction of the bond; this lack of bond directionality is a direct consequence of electron delocalization, and is best understood in contrast to the directional bonding of covalent bonds.
The presence of non-bridging oxygens lowers the relative number of strong bonds in the material and disrupts the network, decreasing the viscosity of the melt and lowering the melting temperature. [17] The alkali metal ions are small and mobile; their presence in a glass allows a degree of electrical conductivity. Their mobility decreases the ...
[citation needed] Diamond is the best natural conductor of heat; it even feels cold to the touch. Its thermal conductivity (2,200 W/m•K) is five times greater than the most conductive metal (Ag at 429); 300 times higher than the least conductive metal (Pu at 6.74); and nearly 4,000 times that of water (0.58) and 100,000 times that of air (0. ...
Liquid armour is a material under research by defense institutions and universities around the world including the United States Army Research Laboratory (ARL). [ 1 ] [ 2 ] [ 3 ] Some of the earliest research in this area was performed at Massachusetts Institute of Technology [ 4 ] and University of Delaware [ 5 ] in 2003.
Such an atom has the following electron configuration: s 2 p 5; this requires only one additional valence electron to form a closed shell. To form an ionic bond, a halogen atom can remove an electron from another atom in order to form an anion (e.g., F −, Cl −, etc.). To form a covalent bond, one electron from the halogen and one electron ...
In this type of bonding, each atom in a metal donates one or more electrons to a "sea" of electrons that reside between many metal atoms. In this sea, each electron is free (by virtue of its wave nature) to be associated with a great many atoms at once. The bond results because the metal atoms become somewhat positively charged due to loss of ...