Preparation of functionalized core-shell poly(BA/MMA-co-MAA) and its application in toughening PBT

A series of core-shell poly(BA/MMA-co-MAA) (PBMMA) latex with different amounts of functional monomer methacrylic acid (MAA) were produced with redox initiator system by seed emulsion polymerization. The overall conversion of the monomers reaches up to 99.6% and almost all the instantaneous conversion is over 96%. The latex particle size (d_z) is 421 nm and the polydispersity index (PDI) is less than 0.08. The experimental values of particle sizes are in accordance with calculated ones, indicating that the particles have grown without significant secondary nucleation. When 0.9% functional monomer (MAA) was used, the Charpy notched impact strength of PBT/PBMMA (mass ratio of 100/20) reaches the maximum, increases to 7.6 times of that of pure PBT resin. DMA spectra show that the internal friction peak of the rubber phase moves to high temperature and the internal friction peak of PBT to low temperature, the mechanical loss peak becomes wider. These results show that the compatibility of PBMMA particles with PBT matrix is the best when 0.9% functional monomer was used. SEM observation confirms the mechanical results.