Compound Preparation, Mixture Characterisation and Process Enhancement of Particulate-Filled Polymer Compounds

Compound Preparation, Mixture Characterisation and Process Enhancement of Particulate-Filled Polymer Compounds 

The term polymer compounding, as it applies to plastics and rubbers, normally describes operations undertaken once the polymer leaves the polymerisation reactor and up to the point where conversion to a finished product takes place, for example, using moulding techniques or die-forming operations based on extrusion. Frequently, compounding is associated with methods for combining polymer with additives, such as fillers, pigments or reinforcements, which may aim to influence its end-performance, appearance, processibility, or simply to reduce overall cost. 

Whilst many of these areas fall outside the scope of this chapter, particulate polymer composites are becoming increasingly complex and commonly require more than just inclusion of a filler or particle additive in order to achieve optimum properties. For example, rubber modification of mineral-filled thermoplastics to yield a balance of enhanced toughness and stiffness, is an area of commercial importance. In these ternary-phase systems, there is not only a requirement to attain good dispersion of the filler component, but also a need for breakdown of the rubbery inclusion to yield the most effective size and spatial location within the composition. Whilst this may depend to a large extent on characteristics of the material s formulation, it can also be influenced by the material s compounding route. 

Reactive modification of polymers is also highly relevant to the preparation of particulate-polymer composites, since the incorporation of functional groups onto an otherwise non-reactive polymer chain, can promote adhesion to the particulate phase, with attendant improvements to physical properties. Adjustments to polymer 

Additional demands may be placed on compounding methods when using high filler loadings, such as the need to convey large amounts of powdered species through the machinery, exacerbated if additives are heat or shear sensitive, or are especially difficult 

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