Chitosan was melt blended with poly-ε-caprolactone (PCL), poly(butylene succinate) (PBS), poly(lactic acid) (PLA), poly(butylene terephthalate adipate) (PBTA), and poly(butylene succinate adipate) (PBSA). For the chitosan/PBS blend, the amount of chitosan was varied from 25% to 70% by weight. The remaining polyesters had 50% of chitosan by weight. Addition of chitosan to PBS or PBSA tends to depress the melting temperature of the polyester. The crystallinity of the polyesters (PCL, PBS, PBSA) containing 50% chitosan decreased. Adding chitosan to the blends decreased the tensile strength but increased the tensile modulus. Chitosan displayed intermediate adhesion to the polyester matrix. Microscopic results indicate that the skin layer is polyester rich, while the core is a blend of chitosan and polyester. Fractured surface of chitosan blended with a high Tg polymer, such as PLA, displayed a brittle fracture. Blends of chitosan with PCL, PBTA, or PBSA display fibrous appearances at the fractured surface due to the stretching of the polymer threads. Increasing the amount of chitosan in the blends also reduced the ductility of the fractured surface. The chitosan phase agglomerated into spherical domains or were clustered into sheaths. Pull-out of chitosan particles is evident in tensile-fractured surfaces for blends of chitosan with ductile polymers but absent in the blends with PLA. PBS displays a less lamellar orientation when compared to PCL or PBSA. The orientation of the polyesters (PCL, PBSA) does not seem to be affected by the addition of chitosan. The two main diffraction peaks observed using WAXS are unaffected by the addition of chitosan.
Bibliographical noteFunding Information:
L.F. Boesel acknowledges Fundação Coordenação de Aperfeiçoamento de Pessoal do Ensino Superior (CAPES-Brasília, Brazil) for the Ph.D. grant. M.B. would like to thank FLAD (Fundação Luso-Americana para o Desenvolvimento) for generous support of sabbatical funds towards this research. Financial support for this work was also provided by FCT through the POCTI and FEDER programs and EU Integrated Project Genostem (Adult Mesenchymal Stem Cells Engineering for connective tissue disorders: from the bench to the bed side).
- Aliphatic polyesters
- Melt processing