Effect of Melting Temperature

The absorption and luminescence spectra of the BF single-doped GGKB glass samples melted at different MTs are shown in Fig. 6.15. BF ion emission is almost totally quenched when the MT increases up to 930 °C. This is in good agreement with the much lowered baseline in absorption spectra. Although it has been inconsistent as to which 

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Figure 8.10. Effect of melt temperature on onset of elastic turbulence in polyethylene. (After Howells...

The effect of melt temperature on nucleation in crystallizing polymers. 

FIG. 15.40 Effect of melt temperature on onset of elastic turbulence in polyethylene. From Brydson (1981, Gen Ref, his Fig. 5.6 as reproduced from Howels and Benbow, 1962). Courtesy The Plastics 8t Rubber Institute. 

The compression-molded part, by definition, does not have flow-induced orientation. Comparison of compression-molded part properties with those of an injection-molded part can show the effect of melt temperature on properties. In the compression-molded article without flow-induced orientation, the impact strength remains constant until a certain melt temperature is surpassed and then decreases. This thermal degradation effect can be attributed to the polybutadiene component, which acts as an initiation site for oxidative degradation of the matrices. 

The effects of melt temperatures of the films before quenching on the crystallization curves were compared at 80° and 100°C. The latter is higher than the glass transition temperature (Tg) of PS block, and the former is lower than the Tg. However, there were no substantial differences in the observed rate curves. It appears that melting above or below Tg of the PS block does not cause substantial change in the size of the PTHF domains. Therefore, the crystallization rate (G) of the block copolymers may be approximated by the equation for homopolymer crystallization (9) ... 

Our primary objective is to determine whether slight differences in the color of heavily pigmented polymer melts can be successfully differentiated by the Vis-NIR system. We will also briefly examine thermochromic phenomena and the effect of melt temperature on color. Finally, the problem of relating color differences measured in-line to data obtained off-line from the same masterbatch when fully diluted in an end-use resin at room temperature will be discussed. 

Fiff. 6. Effect of melting temperature on mean fiber strength and coefficient of variation (after Cameron. 1966),... 

Murthy NS, Kagan VA, Bray RG. Effect of melt temperature and skin-core morphology on the mechanical performance of nylon 6. Polym Eng Sci 2002 42 940-950. 

TGA, dynamic rheological analysis and polarised light microscopy were used to assess thermal stability of PEEK. Emphasis is given to the effect of melting temperature on thermal stability. 23 refs. 

FIGURE 1.16 The effect of melt temperature on the film tear strength of polybutylene film extruded at the rate of 10 m/min. The film thickness is 0.002 in. and the blow up ratio is 2.8. 

N. Sanjeeva Murthy, V. A. Kagan, R. G. Bray. Effect of Melt Temperature and Skin-Core Morphology on the Mechanical Performance of Nylon 6. Polym. Eng. Sci., 42, 940-950 (2002). 

Fig. 2. Effect of polymerization temperature on the crystalline melting point of chloroprene mbbers produced by emulsion polymerization ...

Figure 10.8. Effects of melt flow index and density on the room temperature tough-brittle transition of polyethylene. (Reproduced by permission of ICI)...

Preliminary tests were made on melt mixed blends of PP and LCP to study the effect of processing temperature on the shape and size of the dispersed LCP phase. Extrusion experiments were made below as well as above the melting temperature of the LCP. Two different polypropylenes were tested to determine the effect of the viscosity of the matrix on the final morphology. 

Buffat, P Borel, J.-P. 1976. Size effect on melting temperature of gold particles. Phys. Rev. A 13 2287-2298. 

Altinkaynak, A., Gupta, M., Spalding, M.A., and Crabtree, S.L., Numerical Investigation of the Effect of Screw Temperature on the Melting Profile in a Single-Screw Extruder, SPEANTEC Tech. Papers, 53, 430 (2007)... 

Righter, K., Drake, M. J. and Yaxley, G. (1999) Prediction of siderophile element metal-silicate partition coefficients to 20 GPa and 2800 °C the effects of pressure, temperature, oxygen fugacity, and silicate and metallic melt compositions. Physics of the Earth and Planetary Interiors, 100, 115—134. 

Since Schultz (7) found that ultimate conversion depended considerably on temperature (in a highly polymerized methyl methacrylate system), similar effects would be expected in the postirradiation-heating of the PVC-styrene system. Such effects have indeed been found. Figure 4 shows the effect of heating temperature on the conversion level at two different radiation doses. No increased conversion is found for a temperature higher than 75 °C. This seems to indicate that a more or less definite melting point of the partially polymerized mixture exists. When this temperature is reached during the postirradiation treatment, the reaction runs to a point of termination and is unaffected by further temperature increases. 

The optimum reoxidation temperature, shown in Fig. 20, is about 600°C. This depends to some extent on the type of support. Highly titanated samples produce peak melt indexes at only 300°C. Probably the temperature is needed to bind the chromium to the dehydroxylated support. Above 600°C the activity remains high, but the promotional effect of low temperature attachment is lost, and the MI drops. 

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