Melt density

Density. Although the polymer unit cell dimensions imply a calculated density of 1.33 g/cm at 20°C, and extrapolation of melt density data indicates a density of 1.13 g/cm at 20°C for the amorphous phase, the density actually measured is 1.15—1.26 g/cm, which indicates the presence of numerous voids in the stmcture. 

As the solid material is more dense than the melt, the melt flow rate must be greater in the ratio of the solid/melt densities. Therefore... 

Atomic number Atomic weight Crystal structure Melting Density Thermal Electrical resistivity (at 20°C) Temperature coefficient of resistivity Specific Thermal Standard electrode potential Thermal neutron absorption cross-section. 

Pakula and Zhulina [213] have simulated dry brushes at melt densities in contact with a repulsive wall. They used the cooperative motion algorithm. Their re-... 

Zj helical length of the channel at the barrel wall z(r) helical length of the channel at radial position r Zf, helical length of the metering channel at the barrel wall melt density of the fluid 7 average shear rate in the channel... 

In this chapter the physical properties of resins related to processing will be described. The chapter and Appendix A4 include physical properties for many resins. These properties include bulk density and compaction, lateral stress ratio, stress at a sliding interface, melting flux, heat capacity, thermal conductivity, and melt density. Some of these properties are easy to measure by many laboratories while others such as the melting flux and stress at a sliding interface can be measured in only a few places using highly specialized equipment. 

Single-screw extruders and most other processing machines are volumetric metering devices. That is, the extruder will discharge a volume of resin for each revolution of the screw. Since the processor requires rate data in mass units (kg/h), the melt density is a needed physical property. The melt density for polymers is always less than the solid density of the material, and the melt density decreases further... 

Figure 4.16 Melt densities for select resins as a function of temperature. PVC, PMMA, and PVDF resin data are from Zoller and Walsh [43]. All resins contain only extremely low level of additives...

The target discharge temperature for the extrusion is 240 °C, and the maximum screw speed is 130 rpm (N = 2.167 rev/s). What will be the expected production rates for both resins at 130 rpm At 240 °C the melt density of the resins is 735 kg/mT As presented in Sections 1.4 and 7.4, the net flow in the extruder is the difference between the rotational flow and the flow induced by the pressure gradient Qp. The data in Table 7.2 was calculated from the example in Section 1.5.1 and Table 7.1 ... 

The focus of this evaluation is on the results that were reported using four different resins [52] PC resin, LLDPE resin, EAA copolymer, and an LDPE resin. The shear viscosities for the resins at selected processing temperatures are shown in Pig. 7.17 and were modeled using the power law model provided by Eq. 7.42. The parameters for the model are given in Table 7.3. As shown in Pig. 7.17 and the n values in Table 7.3, the PC resin shear-thinned the least while the EDPE resin shear-thinned the most. The LLDPE and EAA resins have n values between those for the PC and LDPE resins. The melt density for the LDPE and LLDPE resins at 240 °C is 735 kg/mT The melt density of the EAA resin at 220 °C was 785 kg/m and the melt density of the PC resin at 280 °C was 1073 kg/mT... 

Physical properties that need to be obtained for the resins include the shear rheology, melt density, thermal conductivity, and heat capacity. The shear rheology of... 

Stolper E., Walker D., Hager B. H. and Hays J. F (1981). Melt segregation from partially molten source regions The importance of melt density and source region size. J. Geophys. Res., 86 6261-6271. 

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