Macromolecular Modifiers Used as Polymer Processing Aids

5 Macromolecular Modifiers Used as Polymer Processing Aids 

The improvement of polymer processibility without reducing mechanical properties is a very important problem mainly in the case of difficultly processible and thermally unstable polymers. PVC is the most important polymer among these and the use of lubricants as PVC processing aids has been discussed in 

Chapter 2. Some macromolecular modifiers can also act as processing aids, and for PVC the most efficient ones are acrylic and methacrylic polymers, MBS and ABS terpolymers, EVA copolymers, (vinyl chloride)-(vinyl acetate) copolymers, or (vinyl chloride)-propene copolymers. The efficiency of these modifiers as PVC processing aids is related to a good mutual polymer-polymer miscibility. The miscibility of EVA copolymers with PVC depends on the vinyl acetate content of the EVA. The copolymers with more than 50% vinyl acetate are already miscible with PVC, and they are used mainly as processing aids. 

Other examples of commercially available macromolecular processing aids are [111,112]  

Degalan V 26 (Degussa, A.G., B.R.D.). This is a 90/10 (methyl methacrylate)-(butyl acrylate) copolymer. It mixes well with PVC and it does not affect its transparency, water absorption, and electrical properties. It is suitable to modify the rheological properties of impact-PVC. It shortens the plastication time of PVC mixtures and it improves their homogenization and the extrusion output. The addition of Degalan V 26 also improves the heat stability of PVC mixtures and increases the resistance of PVC-based products to heat distortion. 

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