Compatibilizing agent, improvement

It was shown that the clay dispersion was improved with increasing compatibilizing agent, but at the expense of the polymer processability into filaments. Nevertheless, there was no evidence of intercalation or exfoliation, irrespective of the nature of compatibilizer or clay modifier, nor strong improvements of LOI. Despite the absence of formation of true nanocomposites, filaments were sufficiently strong to be knitted into fabrics and presented slower burning behavior than the pure polymer. 

One possible way of reducing interfacial tension and improving phase adhesion between PP-based blend phases is to use a selected copolymeric additive that has similar components to the blend, as a compatibilizer in the blend system. Well-chosen diblock copolymers, widely used as compatibilizing agents in PP-based blends, usually enhance interfacial interaction between phases of blends (15, 16), reduce the particle dimensions of the dispersed phase (16, 17), and stabilize phase dispersion against coalescence (16-18) through an emulsification effect, thus improving the mechanical properties (15-19). 

A copolymer of the two immiscible polymers themselves would seem to be ideally suited to act as a compatibilizing agent for an immiscible blend. If the copolymer is at the interface of the two phases, then the segments of the copolymer dissolve in the respective bulk phases of the same identity. The copolymer acts as emulsifying agent for the blend resulting in reduced interfacial energy and improved interphase adhesion. 

To improve compatibility between phases, the conventional compatibilization strategies have generally been applied, such as the addition of a compatibilizing agent, which can be performed by modification of at least one of the polymers initially present in the blend ... 

The ultimate mechanical properties of HDPE/iPP blends can also be improved by adding a suitable third component, mainly a random ethylene-propylene copolymer (EPM). Such an additive, having intermediate molecular characteristics between the two polymer species, can act as a compatibilizing agent" in their amorphous regions. 

These compatibilizers are, in most cases, copolymers of the two components, which are partly soluble in both phases and act as bridges between the two phases. The compatibilized blends show better properties than those of the same incompatible blends. The improvement depends on the degree of homogeneity given by the compatibilizer agent. 

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