Synthesis and characterisation of star branched polyesters with dendritic cores and the effect of structural variations on zero shear rate viscosity

• A series of branched polyesters consisting of poly(epsilon-caprolactone) (PCL) (degree of polymerisation: 5-200) initiated from hydroxy-functional cores and end-capped with methylmethacrylate have been prepared. The cores were third-generation hyperbranched polyester, Boltorn, with approximately 32 hydroxyl groups, a third-generation dendrimer with 24 hydroxyl groups and a third-generation dendron with eight hydroxyl groups. Finally, a linear PCL was synthesised as a reference material. All initiators were based on 2,2-bis(methylol) propionic acid (bis-MPA). C-13 NMR spectra of the polymers showed that those with shorter arms contained unreacted hydroxyl groups on the core. Rheological measurements of zero shear rate viscosity, eta(0), showed that the branched polyesters had a considerably lower eta(0) than linear polyester with similar molecular weight. The low melt viscosity and the crystallity produced a theological behaviour suitable for the film formation process for powder coatings. Measurements of mechanical properties of cured films showed that those with low arm molecular weight, M-a, were amorphous while those of high M-a were crystalline.

Subject headings

NATURVETENSKAP  -- Kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences (hsv//eng)

Keyword

star branched

zero shear rate viscosity

powder coating

aliphatic polyesters

2

2-bis(hydroxymethyl)propionic acid

hyperbranched polyesters

shaped polymers

powder coatings

polymerization

macromolecules

initiation

behavior

melts

Chemistry

Kemi

Publication and Content Type

ref (subject category)

art (subject category)