Crystallization melting point

The properties of fillers which induence a given end use are many. The overall value of a filler is a complex function of intrinsic material characteristics, eg, tme density, melting point, crystal habit, and chemical composition and of process-dependent factors, eg, particle-si2e distribution, surface chemistry, purity, and bulk density. Fillers impart performance or economic value to the compositions of which they are part. These values, often called functional properties, vary according to the nature of the appHcation. A quantification of the functional properties per unit cost in many cases provides a vaUd criterion for filler comparison and selection. The following are summaries of key filler properties and values. 

Europium (II) sulfide is a black powder possessing a sodium chloride lattice7 and an unknown melting point. Crystals of the sulfide have a golden hue by reflected light. The compound exhibits ferromagnetism8 with a Curie temperature of 17°K. Above this temperature, europium (II) sulfide behaves as a typical paramagnetic compound.2... 

Lipophilicity Molecular size Hydrogen bonding Ionization Melting point, crystal packing... 

Within given molecular weight limits, wax components having higher melting points crystallize in plates. Low-melting-point components crystallize in needles. Others crystallize in mal-shaped conformation. This process is independent of the fuel or oil in which the crystals form. 

Relatively low melting point. (Crystals must grow below the decomposition temperature of the desired phase.)... 

The present study of the Ce-La-Ni system has been undertaken to check the evaluated literature data and aimed at refining the position of phase boundaries in the nickel comer of the Ce-La-Ni system at melting points (crystallization of alloys). Several experimental alloys have been produced at 1-5 at. % intervals in the region rich in nickel. 

Figure 11. Fragment of the phase equilibrium diagram in the nickel comer of the Ce-La-Ni system at melting points (crystallization of alloys).

Molecular formula Molecular weight Melting point Crystal form Powder form Solubility... 

Very impure compounds typically do not crystallize well. Additionally, the target compound can oil out of solution if the solution reaches saturation above the melting point. Crystallizations for purification should be stirred. Crystallizations benefit by seeding with crystalline material therefore, it may be beneficial to purify a small amount of material by column chromatography to determine the melting point, and to have seeds before proceeding with a crystallization. 

Chen SM, Wu GZ, Sha ML et al (2007) Transition of ionic liquid [bmim][PE6] from liquid to high-melting-point crystal when confined in multiwaUed carbon nanotubes. J Am Chem Soc 129 2416-2417... 

Differential thermal analysis (DTA) measures the temperature difference between a sample and a reference as the temperature is increased. A plot of the temperature difference (thermogram) reveals exothermic and endothermic reactions that may occur in the sample. The temperature for thermal events such as phase transitions, melting points, crystallization temperatures, and others can be determined... 

Bronze-colored powder. M.p. 2950°C d 5.21. Somewhat dissociated at the melting point. Crystal structure type B1 (NaCl type). This structure holds for a wide range of compositions (TiNi.o-TiNo.4). Veiy good electrical conductor. 

In case of the metallocene-catalyzed random copolymer of ethylene and alpha-olefin (POP and POE), incorporating more comonomer along the polymer backbone reduces density and crystallinity and hence, increases flexibility and softness. However, as the density is decreased, the melting point, crystallization peak temperature and heat resistance decrease and cycle times in injection molding increase. These deficiencies have limited the use of POEs in applications where heat resistance, high temperature compression set, and faster cycle times are desired. 

The varied stereochemistry of the different metallic elements is well illustrated by -PR,-type complexes (8.68). The configuration may be linear (a), trigonal planar (b), tetrahedral (c), square planar (d), trigonal bipyramidal (e), square pyramidal (f) and octahedral (g). Isomers, which frequently exist among these types of compound (8.63), can usually be distinguished on the basis of their differing melting points, crystal densities or dipole moments. 

The first systematic investigations of the crystallization of glasses were performed by Tammann [2.45,46]. He discovered that the transformation of a melt to a crystalline state consists of two different processes - the nucleation and the crystal growth. When a melt is cooled below the melting point, crystals do not form spontaneously in the entire volume. At first, submicroscopic crystalline aggregates of a definite size, i.e., the nuclei, must form, and only then can crystal growth occur upon these nuclei. The typical curves in Fig. 

Table 3.1 Crystal structure (space group), melting point crystal density g and color of some transition-metal carbides and nitrides, rs = rocksalt.

The UHMWPE fibers show an orthorhombic crystalline structure with low levels of non-orthorhombic crystals [196-99]. Tension along the fiber axis and lateral compression in UHMWPE fibers make crystal transformation from the orthorhombic to the monoclinic form [199, 200]. At high temperatures and temperatures near to melting point, crystal transformation happens through a solid state phase transformation from orthorhombic to pseudohexagonal crystals [195-197, 200]. 

The same effect is obtained when one copolymerizes long chain dibasic acids with terephthalic acid. For example, the ethylene glycol copolyesters of terephthalic acid and sebacic acid, in addition to having lower melt points, crystallize much faster at room temperature because of the increased mobility provided by the flexible molecules. 

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