Polyethylene curves

The DTA thermal curves for two polyolefins are shown in the following figure. Curve 1 is a sample of low-density polyethylene. Curve 2 is a sample of stabilized polypropylene. The melting points, T, are shown,... 

Fig, 7. Variation of second moment with draw ratio for oriented low density polyethylene (curves show results for angles y between Hq and draw direction), (a) experimental airve (b) theoretical curve based on pseudo-affine deformation scheme (after McBrierty and Ward),... 

Plot of relative volume during heating against temperature T. The relative volume is the ratio of the specific volumes at 7 and T . Curve A is for linear polyethylene curve B is for branched pol thylene fedter Mandelkem). 

The DTA thermal curves for two polyolefins are shown in the following figure. Curve 1 is a sample of LD polyethylene. Curve 2 is a sample of stabilized polypropylene. The melting points, T, are shown, (a) What are the melting points for each polymer (b) Which polymer would be better to use for hot water pipes in houses Why (c) What process is occurring at the high-temperature end of each thermal curve ... 

Fig. 4.10. The effect of long-chain branching on the melting process. Plots of relative volume against temperature for linear polyethylene (curve A) and branched polyethylene (curve B). (Reproduced from [21], copyright 1953, American Chemical Society.)...

Figure 3.15 Comparison of the molecular weight distribution for HDPE prepared from the Bis(triphenylsilyl) chromate catalyst and the Phillips catalyst labeled as the commercial polyethylene curve. Reprinted from [17] with permission from John WUey and Sons.

Figure 4.8a shows how this quantity varies with time for polyethylene crystallized at a series of different temperatures. Several aspects of these curves are typical of all polymer crystallizations and deserve comment ... 

Figure 4.8 Fraction of amorphous polyethylene as a function of time for crystallizations conducted at indicated temperatures (a) linear time scale and (b) logarithmic scale. Arrows in (b) indicate shifting curves measured at 126 and 130 to 128°C as described in Example 4.4. [Reprinted with permission from R. H. Doremus, B. W. Roberts, and D. Turnbull (Eds.) Growth and Perfection of Crystals, Wiley, New York, 1958.]...

Fig. 1. Stress—strain curves for ionomer and polyethylene resins. Test speed is 5 cm/min. The reference matedal is high molecular weight conventional...

At temperatures 50°C or so below T, thermoplastics become plastic (hence the name). The stress-strain curve typical of polyethylene or nylon, for example, is shown in Fig. 23.10. It shows three regions. 

Figure 10.6. Effect of temperature on the tensile stress-strain curve for polyethylene. (Low-density polymer -0.92g/cm . MFI = 2.) Rate of extension 190% per minute ...

The specific heat of polyethylene is higher than for most thermoplastics and is strongly dependent on temperature. Low-density materials have a value of about 2.3 J/g at room temperature and a value of 2.9 J/g at 120-140°C. A somewhat schematic representation is given in Figure 10.9. The peaks in these curves may... 

Studies of melt flow properties of polypropylene indicate that it is more non-Newtonian than polyethylene in that the apparent viscosity declines more rapidly with increase in shear rate. The melt viscosity is also more sensitive to temperature. Van der Wegt has shown that if the log (apparent viscosity) is plotted against log (shear stress) for a number of polypropylene grades differing in molecular weight, molecular weight distribution and measured at different temperatures the curves obtained have practically the same shape and differ only in position. 

Polyethylene is extruded through a cylindrical die of radius 3 mm and length 37.5 mm at a rate of 2.12 x 10 m /s. Using the flow curves supplied, calculate the natural time of the process and corrunent on the meaning of the value obtain. ... 

Polyethylene at 170°C passes through the annular die shown, at a rate of 10 x 10 m /s. Using the flow curves provided and assuming the power law index n = 0.33 over the working section of the curves, calculate the total pressure drop through the die. Also estimate the dimensions of the extruded tube. 

FIGURE 4.2 Polyethylene oxide, dextran, and protein calibration curves for TSK-GEL SW Columns. Column TSK-GEL SW, two 7.S mm x 60 cm columns in series. Sample , proteins Q, polyethylene oxides O, dextrans. Elution dextrans and polyethylene oxides distilled water proteins 0.3 A1 NaCI in 0.1 M phosphate buffer, ph 7. Flow rate 1.0 ml/min. Detection UV at 220 nm and Rl. 

The range of pore sizes in which TSK-GEL PW and TSK-GEL PWxi columns are available permits a wide spectrum of water-soluble substances to be analyzed. Calibration curves for polyethylene glycols chromatographed on... 

Figure 6.21 shows the calibration curves of the SB-800 HQ series using standard pullulan. Because a high molecular weight standard sample is not available, the calibration curves of 805 and 806 are partly estimates (dotted lines). The difference in the conformation between polyethylene oxide (PEO) and pullulan in the solvent causes a shift of the calibration curves of pullulan slightly higher than those of PEO. The OHpak SB-800HQ series is better suited for the analysis of hydrophilic samples than the Asahipak GS/GE series. 

Calibration curves for the Ultrahydrogel column family using using polyethylene oxide standards and water as the mobile phase are shown in Fig. 11.12. 

FIGURE 12.7 SEC calibration curves for PL aquagel-OH columns (300 X 7.5 mm), eluent water at 1.0 ml/min, polyethylene oxide/glycol calibrants. 

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