Sink marks depth

Figure 13.2. Sink marks depth measured by stylus profilometer in two stage pressure molding of sheet molding compound vs. release time. [Adapted, by permission, from Dziewatkoski, N. A. Xu, J. Lee, L. J. Castro, J., Polym. Composites, 15, 2,106-17,1994.]...

Surface quality of molded material can be improved not only by composition, but also by regulation and automatization of equipment. Figure 13.2 shows that sink mark depth depends on release time (optimum pressure release time). Molding process can be regulated to take advantage of this principle. ... 

The test specimens consist of test bars Sin. in length and l/2in. in depth by any width from 1/8 to 1/2 in. The test bars may be molded or cut from extruded sheet as long as they have smooth, flat surfaces and are free of excessive sink marks or flash. The specimens are conditioned employing standard conditioning procedures. 

Fig. 6.11 Schematic diagram showing depth relationship between degree of saturation for calcite in seawater and rate of CaC03 dissolution. At 4km depth, as seawater approaches undersaturation with respect to calcite, rate of dissolution of sinking calcite skeletons increases. The lysocline marks this increased rate of dissolution. Below the lysocline only large grains (foraminifera) survive dissolution if buried in the seabed sediment. Below the calcite compensation depth (CCD see text) all CaC03 dissolves, leaving red clays.

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