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Biodegradable polyester blend and copolyesters studied by positron annihilation and other methods

Dębowska M., Rudzińska-Girulska J., Serwadczak M., Kiersnowski A., Pigłowski J.

Nukleonika

2010

Vol. 55, No. 1

57-64

Two polyesters, i.e. an aromatic one: poly(butylene terephthalate) – PBT and an aliphatic one: poly(ĺ- -caprolactone) – PCL were mixed in melt to obtain a biodegradable product. DSC, 1H NMR, SEM, WAXS, SAXS, BOD and PALS measurements were performed to study the homopolymers as well as their physical blend and copolyesters. The latter were obtained due to the transesterification reaction. Ortho-positronium (o-Ps) annihilation lifetimes were used to create the distributions of free volume. The progressive changes in probability density function of free volume, i.e. increase in large free volume holes contribution to the total free volume, appearing when going from the homopolymers to the blend and then to the copolyesters reflect the influence of: the addition of aliphatic polyester, the weight fraction of it in the composition and transesterification. The higher contribution of larger free volume holes corresponds well with the reduced crystallinity of compositions revealed in X-ray diffraction and the worsening of the regularity of structure of the macromolecules involved in formation of crystals, deduced from the 1H NMR.

Structure and mechanical properties of biodegradable copolyesters and blends based on poly (butylenes terephthalate)

Kiersnowski A., Szymczak S., Serwadczak M., Szustakiewicz K., Pisula W., Pigłowski J.

Polish Journal of Applied Chemistry

2009

Vol. 53, nr 3

223-229

The contribution presents results of the research on biodegradable systems based on poly(butylcnc tcrcphthalatc) (PBT) either melt-blended or copolymerizcd with poly( 1,4-butylene succinate) (PTMS) or poly(e-caprolactonc) (PCL). Syntheses of copolycsters were carried out in a twin-screw extruder using of dibutyltin dilaurate as a catalyst. DSC results indicated that the blends were phase-separated systems while copolymcrs were semicrystallinc homogenous materials. The x-ray diffraction was used to study the molecular and supramolecular structure of blends and copolycsters. The results of structural investigation were then correlated with mechanical properties and biodegradability of the obtained materials.