Melting temperature 15 linear

Sharkskin occurs at a lower shear rate than melt fracture, but the term melt fracture is often applied to all regular flow defects including sharkskin. Sharkskin occurs at a critical linear extrusion speed that can be raised by increasing melt temperature. Melt fracture starts at a critical shear stress and can be reduced significantly by reducing the die inlet angle, but, like sharkskin, it is also reduced by raising melt temperature. Linear low-density polyethylene is particularly prone to these defects, but they are minimized by the addition of special additives or blends with other polymers. 

For all the blends the PEO melting temperature linearly increases with following the equation ... 

Not only the melting temperature of DNA but also its density in solution is dependent on relative G C content. G C-rich DNA has a significantly higher density than A T-rich DNA. Furthermore, a linear relationship exists between the buoyant densities of DNA from different sources and their G C content... 

Another important type of condensation polymer are the linear polyesters, such as poly (ethylene terephthalate) (PET) and poly (butylene terephthalate) (PBT). Copolymers of polyesters and PA have been studied in detail, and it has been shown that random copolyesteramides have a low structural order and a low melting temperature. This is even the case for structurally similar systems such as when the group between the ester unit is the same as that between the amide unit, as in caprolactam-caprolactone copolymers (Fig. 3.10).22 Esters and amide units have different cell structures and the structures are not therefore isomorphous. If block copolymers are formed of ester and amide segments, then two melting temperatures are present. 

It is important from a practical viewpoint to predict the shear viscosity of mixtures from those of pure melts. For alkali nitrate melts, a linear dependence has been found between the reorientational line width obtained by Raman measurements and the ratio of temperature divided by shear viscosity.For NO3 ions, the depolarized Raman scattering from 1050cm" total stretching vibrational mode (Al) has a contribution to the line width L, which is caused by the reorientational relaxation time of the Csv axis of this ion. The Stokes-Einstein-Debye(SED) relation establishes a relation between the shear viscosity r of a melt and the relaxation time for the reorientation of a particle immersed in it ... 

Figure 19 (a) Peak melting temperature as a function of the branch content in ethylene-octene copolymers (labelled -O, and symbol —B (symbol, ) and -P (symbol, A) are for ethylene-butene and ethylene-propylene copolymers, respectively) and obtained from homogeneous metallocene catalysts show a linear profile, (b) Ziegler-Natta ethylene-octene copolymers do not show a linear relationship between peak melting point and branch content [125]. Reproduced from Kim and Phillips [125]. Reprinted with permission of John Wiley Sons, Inc. 

Figure 20 Linear dependence of peak melting temperature with branch content in terms of comonomer (left hexene right octene) content from the work of Mirabella and Crist [126]. Reproduced from Mirabella and Crist [126]. Copyright 2004, John Wiley Sons, Inc. Reprinted with permission of Wiley-Liss, Inc., a subsidiary of John Wiley Sons, Inc.

Fig.2 Melting temperatures of polymers (faTm/Ec) with variable chain lengths. The solid line is calculated from Eq. 10, the dashed line is calculated from Flory-Vrij analysis (Eq. 11), and the circles are the simulation results in the optimized approach. In simulations, the occupation density is 0.9375, and the linear size of the cubic box is set to 32 for short chains and 64 for long chains (Hu and Frenkel, unpublished results)...

Fig. 4 Rescaled data from Fig. 3b to show the linear relationship predicted by Eq. 16. The bulk equilibrium melting temperature Ec/k T is chosen to be approximately 0.2. The lines are the results of linear regression, and the symbols are for the variable values of B/Ec [14]...

Fig. 8 Theoretical liquid-liquid demixing curve (solid line) and the bulk melting temperature (dashed line) of a flexible-polymer blend with one component crystallizable and with athermal mixing. The chain lengths are uniform and are 128 units, the linear size of the cubic box is 64, and the occupation density is 0.9375 [86]...

The dynamic mechanical behavior indicates that the glass transition of the rubbery block is basically independent of the butadiene content. Moreover, the melting temperature of the semicrystalline HB block does not show any dependence on composition or architecture of the block copolymer. The above findings combined with the observation of the linear additivity of density and heat of fusion of the block copolymers as a function of composition support the fact that there is a good phase separation of the HI and HB amorphous phases in the solid state of these block copolymers. Future investigations will focus attention on characterizing the melt state of these systems to note if homogeneity exists above Tm. 

Figure 15.2 shows some typical hardness data for a typical metal (copper) as a function of temperature. It indicates that there are usually two regimes one above about half the melting temperature and one below. Both tend to be exponential declines, so they are linear on semi-logrithmic graphs. The temperature at which the break occurs is not strictly fixed, but varies from one metal to another, with the purity of a metal, with grain size, and so on. 

Linear Solvents. For novel solvents that are intended to replace linear carbonates, the emphasis was placed on such properties as melting temperature, viscosity, and inflammability of the solvents. As Table 12 shows, these solvents can be roughly classified into four groups (1) linear esters or carbonates,(2) fluorinated esters,(3) fluorinated carbonates," and (4) fluorinated ethers." " ... 

Whenever dilfusivity rates are not experimentally known and cannot be estimated by static potential calculations, approximate values can be obtained by empirical methods. The most popular of these methods establishes a linear relationship between the enthalpy of the Schottky process (and enthalpy of migration) and the melting temperature of the substance (expressed in K) ... 

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