Highly filled polymer composites

Fig. 30. Design principles of direct compounding injection moulding machine for processing highly filled polymer compositions...

Polymer concrete, as highly filled polymer compositions, can be prepared on any synthetic binding. However, due to the requirements for density, strength, deform-ability, chemical resistance, and other characteristics, about 10 different types of monomers or oligomers are used in practice. In combination with modifying additives, they provide more than 30 varieties of polymer concrete. 

For all high-filled polymers, whatever the nature of the matrix and filler, it has been found [297,298] that the Bagley pressure loss at extruder inlet increases sharply in a certain range of temperatures and rates of deformation. What distinguishes composites with PMF is that for them the pressure loss at the inlet begins at lower deformation rates. 

Obviously, typical composite propellants are highly filled polymers and, especially in the case of the rubber-based systems, are more nearly granular media than merely filled rubbers. Certain specific differences between the double-base binder and the elastomeric binder lead to some differences in behavior, but many of the resulting properties show similarities. The relationships between bulk properties and microstructure in the rubber-based systems are much better understood than those of the double-base propellants and, therefore, the following discussions focus primarily on the former category. 

There is no sharp dividing line between plastic mortars and sealants, but the former are usually in situ-polymerized, highly-filled, rigid composites while the latter are usually in sltu-polymerized, flexible polymers. Since plastic mortars do not require expensive molds, the phenolic and urea plastic motars were the pioneer plastics. The Interest in these readily fabricated, labor-intensive, plastics decreased as automated molding processes were developed. However, because of their excellent properties and the need to conserve energy, there is an renewed interest in these materials. 

Henderson, J.B. and Emmerich, W.D. (1988) Measurement of the specific heat of a glass-filled polymer composite to high temperatures. Thermochim. Acta, 131, 7 14. 

Saini, D.R., Shenoy, A.V. and Nadkami, V.M. (1986) Melt rheology of highly loaded ferrite-filled polymer composites, Polym. Composites, 7, 193-200. 

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