Crystallization melting range

TABLE I. CRYSTAL MELTING RANGES OF SOME STEREOREGULAR POLYMERS... 

Properties Colorless crystals. Melting range 84—88C, specific rotation +105-112 degrees. Unstable in light and air. Insoluble in water soluble in alcohol, chloroform, and fatty oils. 

Ethyl bis-(2,4-dinitrophenyl) acetate (indicator) the stock solution is prepared by saturating a solution containing equal volumes of alcohol and acetone with the indicator pH range colorless 7.4-9.1 deep blue. This compound is available commercially. The preparation of this compound is described by Fehnel and Amstutz, Ind. Eng. Chem., Anal. Ed. 16 53 (1944), and by von Richter, Ber. 21 2470 (1888), who recommended it for the titration of orange- and red-colored solutions or dark oils in which the endpoint of phenol-phthalein is not easily visible. The indicator is an orange solid which after crystallization from benzene gives pale yellow crystals melting at 150-153.5°C, uncorrected. 

An intrinsic surface is built up between both phases in coexistence at a first-order phase transition. For the hard sphere crystal-melt interface [51] density, pressure and stress profiles were calculated, showing that the transition from crystal to fluid occurs over a narrow range of only two to three crystal layers. Crystal growth rate constants of a Lennard-Jones (100) surface [52] were calculated from the fluctuations of interfaces. There is evidence for bcc ordering at the surface of a critical fee nucleus [53]. 

Steady-state crystallization rates were measured for a range of temperatures below the melting point by Broughton et al (13). A face-centered cubic (100) crystal-melt interface was equilibrated in a box elongated in the... 

The view that the degree of imperfection depends on the amount of supercooling is borne out by the observations of Bekkedahl and Wood on rubber. They showed that the melting range (for fast melting) is lower the lower the temperature at which the rubber had been allowed to crystallize. Other crystalline polymers exhibit parallel behavior. 

A T = 5.5-13 K under high pressure, P = 0.4 GPa. I was estimated by transmission electron microscopy (TEM). As schematically shown in Fig. 4, ECSCs or FCCs once melted were kept at Tmax = 160 °C for 5 min at atmospheric pressure. After that, samples were isothermally crystallized at various Tcs. Hereafter, we abbreviate these processes as ECSCs-melt-FCSC or FCCs-melt-FCSC, respectively, where FCSC means folded chain single crystal. The range of AT was about 10-14 K. 

A melting point is the temperature at which the first crystal just starts to melt until the temperature at which the last crystal just disappears. Thus the melting point (abbreviated M.P.) is acually a melting range. You should report it as such, even though it is called a melting point, for example, M.P. 147-149°C. 

Ueda et al. [26] recently investigated a flow-oriented PE-fr-aPP diblock copolymer with Mw = 113 000 (Mn/Mw = 1.1) and a PE volume fraction of 0.48. This diblock copolymer is in the strong segregation regime (i.e., estimated xN = 10.5 and Todt = 290 °C) and has a lamellar morphology in the melt. They found a breakout phenomenon with the formation of spherulites in an intermediate crystallization temperature range 95 < Tc < 101 °C. At crystallization temperatures above 101 °C or below 95 °C spherulites were not formed and the crystallization was confined within the lamellar MD. Ueda et al. report that lamellar MD and spherulites do not co-exist when the material crystallizes from the melt which is separated in lamellar MDs. In other words, in this particular case, breakout or confined crystallization within lamellar MDs depends on the crystallization conditions. 

The crystallization of the acetone-insoluble polystyrene is completed by boiling for 2 h in freshly distilled butanone it is then allowed to stand overnight at room temperature and finally filtered and dried in vacuum at 60 °C. Yield of crystalline isotactic polystyrene 95-100% of the acetone insoluble portion.The crystalline melting range and the density see Sect. 2.3.4.1) are determined, as is also the limiting viscosity number in toluene at 20 °C. 

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