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The main goal of this work is to correlate morphological parameters of the binary blend of polyamide 6 (PA6) and a polylactide (PLA) based biodegradable co-polyester blend (BioFlex) (scanning electron microscopy, solvent extraction method) with the solid-state mechanical properties (stress strain analysis) as well as thermal (differential scanning calorimetry) and selected physico-chemical characteristics (Fourier transform infrared spectroscopy and water uptake analysis). The blends of PA6/BioFlex were prepared in ratios of 100/0, 90/10, 75/25, 60/40, 50/50, 40/60, 25/75, 10/90 and 0/100 in wt.%. The occurrence of co-continuous morphology was observed within the range of 40 to 60 wt.% of BioFlex. Furthermore, the results show that the co-continuous morphology of PA6/BioFlex blends significantly affected both tensile (E modulus) and thermal properties (melting enthalpy) of the blends. In the case of the tensile properties, the effect of the morphological arrangement was strongly dependent on the deformation range. The presence of BioFlex in the blends reduced the crystallizability of PA6 noticeably. Co-continuous structure formation was observed to have a significant effect on the melting enthalpy of the blend. Composition morphology dependent responses were observed in the case of the FTIR and water uptake studies. [ABSTRACT FROM PUBLISHER]

Fully and partially hydrolyzed poly(vinyl alcohol) (PVA) was modified with zinc sulphate in the concentration range from 0 to 9 wt% of recalculated zinc content using the solvent cast technique. The resulting polymeric films were characterized by optical microscopy, stress–strain analysis, differential scanning calorimetry and Fourier transform infrared spectroscopy (FT-IR–ATR). In addition, agar diffusion test and dilution and spread plate technique were used for determination of antibacterial properties of the films against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli, Pseudomonas aeruginosa and Klebsiella pneumoniae) bacterial strains. A mathematical model was applied on the measured data and parameters characterizing the antibacterial efficiency of the material were calculated and discussed. The results revealed that the PVA hydrolysis degree can play an important role in all studied properties, including antibacterial activity of the all PVA-based materials. [ABSTRACT FROM AUTHOR]

Poly(vinyl alcohol) (PVA) was modified by zinc nitrate in the concentration range from 0 to 22.29 wt.% using the solvent cast technique. The resulting material was characterized by optical microscopy, stress-strain analysis, differential scanning calorimetry, UV-visible spectroscopy, and Fourier transform-infrared spectroscopy. In addition, the antibacterial properties of the prepared films were tested against the both gram positive and gram negative bacterial strains. The results show the uniform distribution of the modifier within the PVA matrix, enhanced mechanical properties (up to 8.24 wt.%), and good antibacterial activity against gram negative bacteria at low modifier content. [ABSTRACT FROM AUTHOR]

This study is focussed on micro-encapsulation of essential oils in polylactic acid (PLA) and a poly(methyl methacrylate) (PMMA) matrix as well as blends of the same. Microspheres were prepared by the solvent evaporation technique and characterised by scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and Fourier transform infra-red spectroscopy (FTIR). The encapsulation efficiencies and release profiles of the essential oils were studied by gas chromatography mass spectrometry (GC-MS) and head-space solid-phase microextraction GC-MS, respectively. Furthermore, the microspheres were tested for antibacterial activity against both Gram-negative and Gram-positive bacterial strains. The results showed that the microspheres compositions (PLA/PMMA ratio) have significant effect on their characteristics. The process adopted for preparing the microspheres promoted formation of spherical particles at the sizes of 1.5–9.5 µm. The highest encapsulation efficiency of the prepared microspheres was observed in systems consisting of linalool (81.10 ± 10.0 wt. % for PLA system and 76.0 ± 3.3 wt. % for PMMA system). Confirmation was also made that the release rate of the microspheres was affected by the size of the same. [ABSTRACT FROM AUTHOR]

There are several methods for synthesizing polylactic acid. Solid-state polymerization is one of the most promising methods due to the great feasibility and beneficial properties of the final polymer. In terms of this study, the purpose was to evaluate the effect of various catalyst systems (based on tin dichloride, tin dioxide, tin octoate, citric acid, sulphuric acid, toluenesulfonic acid and methane sulfonic acid) and focus on the molecular weight, structure and thermal properties of the final products. The molecular weight was shown to be controlled by different catalytic systems and Mw > 100,000 g/mol was achieved after 24 h of synthesis, which is more than in the conventional melt polycondensation process. Thermal stability was found to be negatively affected by the catalytic system, although relatively positive results can still be achieved. [ABSTRACT FROM PUBLISHER]

This work is focused on preparation of novel porous type of core–shell-structured microparticles based on polylactide (shell) and poly(vinyl alcohol) cross-linked with glutaric acid (GA) (core) prepared by water-in-oil-in-water solvent evaporation technique. The microparticle systems were used as delivery systems for immobilisation of model antibacterial agent – nisin. The effect of cross-linking and the initial amount of nisin on their morphology was investigated using scanning electron microscopy, BET analysis, zeta potential measurement and Fourier transform infra-red spectroscopy. Encapsulation efficiency and release profile of nisin from the microparticles were studied by high performance liquid chromatography. Antibacterial activity of the prepared systems was tested by dilution and spread plate technique. Results showed the microparticles in the size range of 9–16 μm in diameter with spherical multi-hollow core–shell structure. The presence of cross-linking agent GA influences the release profile of the peptide and has synergistic effect onListeria monocytogenesgrowth reduction. [ABSTRACT FROM AUTHOR]

Medical-grade polyvinyl chloride was modified by incorporation of silver nitrate in a concentration range from 0 to 5 wt.% using a solvent casting technique. Agar diffusion test was performed to evaluate in-vitro antimicrobial properties of prepared samples. The obtained systems were characterized by tensile test, X-ray photoelectron spectroscopy, scanning electron microscopy, and optical microscopy. The micrographs revealed a better morphological disposition of silver particles along the polyvinyl chloride matrix in the samples cast fromN,N-dimethylformamide. Nevertheless, the applied modification did not appreciably influence the tensile properties of the prepared systems compared to the reference samples. [ABSTRACT FROM AUTHOR]

The morphology and viscoelastic properties of newly prepared partially biodegradable polymeric blend based on polyamide 6 and commercially available co-polyester of polylactide, BioFlex®, were studied in this work. Observations by scanning electron microscopy and solvent extraction method, and rheological measurements were carried out for structural studies. Experimental data were compared with several semi-empirical models for determination of phase inversion concentration. The correlation between experimental data and models reveals the significant contribution of elasticity effect to interfacial adhesion between polyamide 6 and BioFlex, which seems to have influence on the phase inversion composition of the blends and co-continuous morphology formation. [ABSTRACT FROM AUTHOR]