PBT Blends with Styrenic Copolymers

As noted above, PBT forms well-compatibilized blends with SAN. Usually an ABS resin is used to improve practical impact. ABS resins impart to the blend less shrink and better dimensional stability. The ABS is present as a separate 

PBT has also been blended witli styrene-maleic anhydride (SMA) copolymers giving materials similar to tire ABS blends. Impact modification appears to be more difficult, and one must always be attentive to possible melt reaction witli the anhydride, or its ring-opened acid forms, and the PBT resin. 

One could be tempted to overcome the modulus loss in PBT-rubber blends by adding glass or mineral to the rubber-modified blends. While this works to some extent, the effect of the filler or reinforcement is to limit the ductility of the blend. 

---