Melting block hydrides

Fig. 9.6 Trends in (a) melting and (b) boiling points for some i-block hydrides, EH .

The interstitial carbides are compounds formed by the direct reaction of a d-block metal and carbon at temperatures above 2000°C. In these compounds, the C atoms occupy the gaps between the metal atoms, as do the H atoms in metallic hydrides (see Fig. 14.9). Here, however, the C atoms pin the metal atoms together into a rigid structure, resulting in very hard substances with melting points often well above 3000°C. Tungsten carbide, WC, is used for the cutting surfaces of drills, and iron carbide, FesC, is an important component of steel. 

Synthesis of PDMS-b-(e-caprolactam) ABA block copolymers was reported 343 In these reactions, anhydride-terminated PDMS oligomers were used to initiate the polymerization of -caprolactam in the presence of a catalytic amount of sodium hydride in melt at 130 °C. Under these conditions, the reaction was reported to be completed in... 

Trends in boiling points, melting points and enthalpies of vaporization for p-block binary hydrides... 

Nitrides of the J-block metals are hard, inert solids which resemble metals in appearance, and have high melting points and electrical conductivities (see Box 14.5). They can be prepared from the metal or metal hydride with N2 or NH3 at high temperatures. Most possess structures in which the nitrogen atoms occupy octahedral holes in a close-packed metal lattice. Full occupancy of these holes leads to the stoichiometry MN (e.g. TiN, ZrN, HfN, VN, NbN) cubic close-packing of the metal atoms and an NaCl lattice for the nitride MN is favoured for metals in the earhest groups of the J-block. 

The silicone semi-lPNs consist of mixing a hydride-containing silicone prepolymer and a vinyl functionalized silicone polymer into a thermoplastic matrix such as PA, PBT, thermoplastic polyurethane (TPU) or styrene-ethylene/butylene-styrene (S-EB-S) block copolymer elastomer. The two silicone prepolymers co-react in the thermoplastic matrix during melt extrusion and injection molding to form a partially crosslinked network within the thermoplastic matrix. 

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