Island morphology

The solvent-etched fracture surface of folly cured PEI modified epoxy with different composition is shown in Figure 3.8. For PEI content smaller than 10wt%, the PEI-rich phase is dispersed in a continuous epoxy-rich matrix [i.e., sea-island morphology is observed (a and b)]. Above 25 wt% PEI content, nodular structure was observed (e and f) where the epoxy-rich phase forms spherical nodules and the PEI rich phase forms the matrix. With PEI content between 15 wt% and 20 wt%, dual phase morphology, where sea-island morphology and epoxy nodular structure coexist, is present (c and d). Similar morphology was observed in PEI/BPACY blend [47],... 

Table 3.2 shows the influence of the initial PEI concentration on the resulting particle size distribution. Both the size and the number of PEI domains increased in the sea-island morphology, whereas the size of thermoset nodule decreased and the number of nodules increased in the nodular morphology as the initial PEI concentration was increased. 

In the composition range where the sea-island morphology was shown, the increase of the PEI concentration caused an increase in the PEI phase volume and a lowering of the... 

The method of filler incorporation also determines its distribution between the phases. When PE/TPU blend was in the molten state when mixed with carbon black, the island morphology was obtained with carbon black mostly resident in one phase. Mixing at room temperature followed by cold molding (50°C) resulted in the mixture with uniformly distributed carbon black. ... 

Kim et al (1999) examined the morphology and cure of semi-IPN epoxy resin or dicyanate-polyimide/polysulfone-carbon-flbre Aims. Polyimide or polysulfone Aims were inserted into the curing epoxy-dicyanate monomers to form semi-IPNs with sea-island morphology at the thermoset-thermoplastic interface. The final carbon-flbre-thermoplastic-dicyanate Aims had fracture toughness three to five times higher than that of unmodified carbon-flbre-dicyanate composites. 

Figure 1.19a illustrates the problem of poor microscopic morphology in the case of a CZTS film prepared from a Cu/Sn/Zn precursor with the island structure shown in Figure 1.18. The sulfurized CZTS film contains small grains, and the morphology is uneven. Figures 1.19b and 1.19c show elemental distribution maps for Sn and Zn over the same area. The contrast variations in the two elemental maps are not coincident, suggesting that the film contains other phases besides CZTS. These variations probably arise from the island morphology of the Sn layer in the precursor seen in Figure 1.18, which was not laterally homogenized during sulfurization.

Fig. 3 Schematic representation of two possible surface morphologies, a Hexagonally arranged semi-spheres of B block (island morphology) b parallel oriented semi cylinders of B (ribbon morphology) (Reproduced with permission from [36]. Copyright 1999 American Chemical Society)...

Barrier islands overlying poorly consolidated substrates experience increased rates of relative sea level rise because of the decrease in elevation due to subsidence. These types of barrier island systems can exist near river deltas, as deltaic sediments are reworked by coastal processes, and on the open coast as islands have migrated landward over bay sediment or a peat substrate. Potentially, one-third of the more than 3,600 km of continental US barrier islands consists of a sandy island morphology that overlies poorly consolidated sediment. 

M. O. Hayes, Barrier island morphology as a function of tidal and wave regime. Barrier Islands, ed. S. P. Leatherman (Academic Press, 1979), pp. 1-28. 

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