One-dimensional melting

Recalling the discussion earlier in this chapter, in most cases melting in the channel typically occurs at all four edges of the solid bed, with the majority of the melting occurring at the solid bed-melt film interface located between the solid bed and the barrel wall, as shown in Eig. 6.2. The newly molten resin from this location is then conveyed by the motion of the screw to a melt pool located at the pushing side of the channel. Eor very special and sometimes unpredictable conditions, the melting process can occur by a different mechanism. In these cases, the 

This is consistent with the observations of Tang [31] when evaluating PP melting. In his experiments, the melting mechanism could be switched from the conventional mechanism as shown by the photographs in Fig. 6.30 to a one-dimensional 

The potential cause of these differences in melting mechanisms may be found in the pressure development in the delay zone as described by Kacir and Tadmor [59] and the source of the energy needed for melting. For the delay zone, it is generally 

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Figure 6.28 Photograph of a PVDC powder resin that is melting via the one-dimensional melting mechanism. Even at this early location in the melting process, the thickness of the melt film adjacent to the barrel wall was thicker than normal...

Figure 6.29 Conceptual melting physics for one-dimensional melting. The cream color represents molten resin. The dark color is a mixture of solid polymer particles with molten resin in the void regions...

Figure 6.31 Photographs of one-dimensional melting of the same commercial PP resin as used in Fig. 6.30. Melt pools do not form under these conditions. The screw was rotated at 7 rpm and the barrel temperature was 100°C...

Figure 6.33 Simulation results for melting only from the barrel surface, that is, one-dimensional melting. About 75% of the resin was melted at the end of the transition seotion. The bed height Y in this ease decreases essentially at the same rate that the channel depth decreases...

Campbell, G.A. One-Dimensional Melting in Single-Screw Extruders, SPE ANTEC Tech. Papers, 57, 1367 (2011)... 

According to Spiegelman and Elliott (1993), the consequences of melt transport through a steady-state dCj/dt = 0), one-dimensional melting column on the concentration of radioacitive isotopes can be... 

For melt as porous flow, the enrichment factors due to melt transport over batch melting at variable depths in a one dimensional melting column are given by (5.95), (5.96) and (5.97). 

In a frame fixed to the matrix, the mass conservation equation for the solid and melt in a one-dimensional melting column is (McKenzie, 1984 Richter and McKenzie, 1984 Navon and Stolper, 1987)... 

Maximum and Minimum Bounds on One-Dimensional Melt Thickness... 

According to Coulomb, there occurs a kind of one-dimensional melting with the formation of a 2-D liquid crystal state. 

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