The influence of composition of porous copolyester scaffolds on reactions induced by irradiation sterilization

• In our previous work regarding radiation sterilization of porous scaffolds we have concluded that the composition and microstructure of the polymer chain are a key factor influencing the degradation reactions occurring upon irradiation. In this work we in contrast reported on the effects of high-energy irradiation on the thermal and mechanical properties. Electron beam (EB)- and T-irradiation sterilization were used in order to finalize the properties of a series of porous scaffolds comprised of different aliphatic polyester copolymers. The results presented here show that, for both sterilization methods, the crystallinity increased for all copolymers of 1,5-dioxepan-2-one (DXO) and L,L-lactide (LLA) at the minimum sterilization dose. The same was true of the P.-caprolactone (CL)- and LLA-containing copolymers upon EB sterilization, while a reduction in crystallinity were found upon gamma-irradiation. As was anticipated, it was shown that crystallinity also is a characteristic of the copolymer influencing the effects of the irradiation-induced reactions. Both the onset temperature and the temperature corresponding to the maximum rate of weight loss increased after irradiation and hence the thermal stability was increased. This is a result of a simultaneous lengthening of the chains by cross-linking reactions and a shortening by random chain-scissions occurring throughout the molecule, which lead to the formation of new endgroups with higher thermal stability. Scaffolds of crystalline polymers retained more of their initial tensile properties after irradiation compared to amorphous materials. The result previously published, showing that the composition was a key factor influencing the degradation reactions occurring upon irradiation, was augmented here.

Nyckelord

copolymer

sterilization

electron beam

gamma irradiation

POLY-EPSILON-CAPROLACTONE

ALIPHATIC POLYESTERS

THERMAL-DEGRADATION

L-LACTIDE

POLY(LACTIDE-CO-GLYCOLIDE) PLGA

STRUCTURAL INVESTIGATIONS

RADIATION STERILIZATION

POLY(L-LACTIDE) PLLA

MASS-SPECTROMETER

CYCLIC DIMER

TECHNOLOGY

TEKNIKVETENSKAP

Publikations- och innehållstyp

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