Incorporation of Liquid Additives and Dispersions by Direct Addition

Incorporation of Liquid Additives and Dispersions by Direct Addition 

Many plastics additives are either liquids or solids which will melt at plastics processing temperatures. Some examples are shown in Table 12.1. 

Tackifiers/oils Pallet and silage wrap, adhesives. 

Peroxides for crosslinking Foams, cables, heating pipes 

Chemical foaming agents Physical foaming agents Insulation, packaging, wood substitutes 

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Incorporation of Liquid Additives and Dispersions by Direct Addition Figure 12.14 shows the individual extrusion stages ... 

Recently, an entirely new approach to prepare porous materials was developed by templating the structure of solid CO2 by directional freezing [36]. In this process, a liquid CO2 solution was frozen in liquid nitrogen uni-directionaUy. The solid CO2 was subsequently removed by direct sublimation to yield a porous, solvent-free structure with no additional purification steps (Fig. 1). Other C02-soluble actives could be incorporated into the porous structure uniformly. This was demonstrated by dispersing oil red uniformly in the aligned porous sugar acetates [36]. This method differs fundamentally from the other C02-based techniques [ 14-29], and offers the unique advantage... 

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