Crazing of the fibers based on biodegradable polyesters

Trofimchuk, E.; Khavpachev, M.; Moskvina, M.; Demina, V.; Nikonorova, N.

Авторы: Trofimchuk E., Khavpachev M., Moskvina M., Demina V., Nikonorova N.
Сборник: Book of Abstracts "Virtual Conference on Chemistry and its Applications"
Тезисы
Год издания: 2020
Место издания: University of Mauritius
Первая страница: 136
Последняя страница: 136
Аннотация: In this work, we propose to use the structural modification according to the crazing mechanism for obtaining biologically active suture materials based on polyester fibers. The objects of the study were isotropic fibers with diameters of 700-750 μm from polylactide (PLA), poly(ε-caprolactone) (PCL), and poly(L-lactide-co-ε-caprolactone) (PLLA-co-PCL). The stretching of the PLA fibers in ethanol occurs at low mechanical stress (less than 20 MPa) and is accompanied by the formation of crazes. Importantly no neck is formed, while the crazes develop through all stages, namely, their nucleation, growth, widening, and collapse to the tensile strain of 600-700%. Uniaxial deformation of semi-crystalline polymers in ethanol occurs approximately the same way as in air. However, when PCL fibers are stretched at very low speeds (1 mm/min), it is possible to implement the so-called delocalized crazing, when pores appear simultaneously throughout the volume in intercrystalline parts due to the expansion of the lamellas. The uniaxial stretching of the copolymer of PLLA-co-PCL in air or ethanol is accompanied neither by the formation of crazes, nor by the formation of a neck. In this case, a uniform stretching of the fiber occurs with a gradual decrease in its cross-sectional area up to a break of 600-1100%. At high tensile strain of 600-700%, the fiber suddenly whitens. The cause of this phenomenon may be the formation of pores in the copolymer fiber. The obtained porous fibers by the crazing mechanism were filled with various antimicrobial functional additives - brilliant green, iodine, silver. These fibrous materials have been tested for antimicrobial activity against gram-positive (Staphylococcus aureus and Rhodococcus erythropolis Х5) and gram-negative (Escherichia coli) bacteria and the Candida mycotic culture. Brilliant green-containing fibers have been found to exhibit a pronounced antimicrobial activity with respect to Candida and Escherichia coli cultures. The diameter of the zone of growth-retardation of microorganisms has appeared to be 6–7 mm at a fiber diameter of 350 µm.
Добавил в систему: Трофимчук Елена Сергеевна

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