Stress at a Sliding Interface

For a specific resin, the shear stress at the interface depends on the temperature of the interface, pressure, and the sliding velocity, it also depends on resin type, additives and additive levels, and the rheological properties of the resin. Stresses at the interface and the coefficients of friction for numerous resins have been published previously from two sources, and the data can be found in the references [15-31]. Additional stress data are provided in Appendix A4 and in several of the case studies in Chapter 12. 

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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. 

This section wiil compare the modified Campbeii-Dontula modei to the experimen-tai data for the LDPE resin. The physicai properties for this resin were provided in Section 5.3.2. The dynamic coefficients of friction are avaiiahie in Appendix A5 and are reported as stress at a sliding interface. The coefficient of friction is related to the stress at a sliding interface as follows ... 

Figure 13.6 Stress at a sliding interface for TPU resin at a pressure of 1.4 MPa...

Appendix A4 Shear Stress at a Sliding Interface and Melting Fluxes for Select Resins... 

Table A4.1 Data for Shear Stresses at a Sliding Interface for Select Resins in this Book...

Figure A4.1 Shear stress at a sliding interface for a PC resin with an MFR of 3 dg/min (300 °C, 1.2 kg) as a function of temperature and sliding velocity at a pressure of 0.7 MPa...

Shear stresses at a sliding interface and the melting fluxes for LDPE, ABS, HIPS, and LLDPE were reported at a pressure of 0.7 MPa and as a function of temperature and velocity. These data contribute to the better understanding of the solids conveying and melting processes in single-screw, plasticating extruders. 

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