Polyamides also forces, between chains

Solid additives in the shape of spheres, cubes, or platelets generally act as a filler (extender) and, with the exception of raising stiffness, do not Improve the mechanical properties of the composite. With very strong adhesive forces between filler surface and polymer chains, however, a filler may also provide reinforcement, for example, carbon black in rubber or uncoated calcium carbonate in polyamides. 

The external plasticizing method is applied most frequently to polyvinyl chloride (PVC). The distance between the macromolecules of the plastics is increased by incorporation of plasticizer molecules [aromatic plasticizers, e.g., tricresyl phosphate (TCP) and aliphatic plasticizers, e.g., dioctyl phthalate (DOP) or dioctyl sebacate (DOS)]. This reduces the secondary bonding forces and increases chain segment mobility. Solvents (including water in polyamides) may also act by inward diffusion in a manner similar to plasticizers [11]. 

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