Abstract
Ultrathin electrospun fibers of pristine biopolyesters, poly(3-hydroxybutyrate) (PHB) and polylactic acid (PLA), as well as their blends, have been obtained and then explored after exposure to hydrolytic (phosphate buffer) and oxidative (ozone) media. All the fibers were obtained from a co-solvent, chloroform, by solution-mode electrospinning. The structure, morphology, and segmental dynamic behavior of the fibers have been determined by optical microscopy, SEM, ESR, and others. The isotherms of water absorption have been obtained and the deviation from linearity (the Henry low) was analyzed by the simplified model. For PHB-PLA fibers, the loss weight increments as the reaction on hydrolysis are symbate to water absorption capacity. It was shown that the ozonolysis of blend fibrils has a two-stage character which is typical for O3 consumption, namely, the pendant group’s oxidation and the autodegradation of polymer molecules with chain rupturing. The first stage of ozonolysis has a quasi-zero-order reaction. A subsequent second reaction stage comprising the back-bone destruction has a reaction order that differs from the zero order. The fibrous blend PLA/PHB ratio affects the rate of hydrolysis and ozonolysis so that the fibers with prevalent content of PLA display poor resistance to degradation in aqueous and gaseous media.
Highlights
Eco-friendly, fully biodegradable materials—films with micrometric diapason of thickness and the ultrathin fibers with submicrometric diameters—are in peak demand for a constructive and special performance in such areas as biomedicine [1,2], packaging [3,4], environment protection [5], etc
The water absorption capacity depends on the chemical nature of the macromolecules, polymer crystallinity, surface special features, and volume morphology, as well as on the fibril porosity, interfibrillar space of the mats, and other structural factors
The equilibrium moisture absorption values of the non-woven fibrous materials based on PHB, polylactic acid (PLA), and their binary blends were briefly reported earlier in [35,36]
Summary
Eco-friendly, fully biodegradable materials—films with micrometric diapason of thickness and the ultrathin fibers with submicrometric diameters—are in peak demand for a constructive and special performance in such areas as biomedicine [1,2], packaging [3,4], environment protection (eco-friendly absorbents and ) [5], etc. Biodegradable barrier films [10,11], biopolymer ultrathin fibers are beginning to be used for the transition from passive conventional packaging to active smart packaging, which is devoted to the enhancement of food’s shelf-life [12,13]. Another area of electrospun fiber application—no less important than the previous ones—is the efficient elimination of disastrous anthropogenic consequences resulting from both local and global spill accidents [14]. For the achievement of the desired water quality, its high-effective separation from oil pollutions can be carried out by nanostructured polymer adsorbents characterized by highly developed surfaces with relevant hydrophilic–hydrophobic ratios [15,16]
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