Polyesters
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Anaerobic processes for the treatment of plastic materials waste represent versatile and effective approach in environmental protection and solid waste management. In this work, anaerobic biodegradability of model aliphatic polyesters, poly(L-lactic acid) (PLA), and poly(ɛ-caprolactone) (PCL), in the form of powder and melt-pressed films with varying molar mass, was studied. Biogas production was explored in batch laboratory trials at 55 ± 1°C under a nitrogen atmosphere. The inoculum used was thermophilic digested sludge (total solids concentration of 2.9%) from operating digesters at the Central Waste Water Treatment Plant in Prague, Czech Republic. Methanogenic biodegradation of PCLs typically yielded from 54 to 60% of the theoretical biogas yield. The biodegradability of PLAs achieved from 56 to 84% of the theoretical value. High biogas yield (up to 677 mL/g TS) with high methane content (more than 60%), comparable with conventionally processed materials, confirmed the potential of polyester samples for anaerobic treatment in the case of their exploitation in agriculture or as a packaging material in the food industry.
- MeSH
- anaerobióza MeSH
- biopaliva analýza MeSH
- bioreaktory * MeSH
- chemické látky znečišťující vodu chemie metabolismus MeSH
- dusík MeSH
- kyselina mléčná MeSH
- methan metabolismus MeSH
- odpad tekutý - odstraňování metody MeSH
- odpadní vody MeSH
- polyestery chemie metabolismus MeSH
- teoretické modely MeSH
- tuhý odpad analýza MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The aim of this study is to evaluate and describe the phenomenon and mechanism of the spontaneous cyclic swelling and deswelling of linear and branched aliphatic polyesters in the aqueous medium. The fluctuation of gel volume in one or several cycles as an inherent property of biodegradable and bioerodible materials has not yet been described. We have observed the process at linear and branched polyesters of aliphatic α-hydroxy acids. The period of duration of cycles was in order of hours to days, as influenced by the size of the bodies ranging from 25 to 1000 mg, the temperature in the range of 7°C-42°C, ionic strength, and pH value. The results demonstrated that swelling is accompanied by hydrolysis of ester bonds with the development of small water-soluble osmotically active molecules. After reaching a higher degree of swelling, the obstruction effect of the gel decreases and the diffusion of soluble degradation products from the body to the environment prevails. A decrease in osmotic pressure inside the body and a decrease in the hydrophilic character of the gel matrix result in deswelling by a collapse of the structure, probably due to hydrophobic interactions of nonpolar polyester chains.
- MeSH
- časové faktory MeSH
- chemické modely MeSH
- difuze MeSH
- hydrofobní a hydrofilní interakce MeSH
- hydrolýza MeSH
- koncentrace vodíkových iontů MeSH
- molekulární struktura MeSH
- osmolární koncentrace MeSH
- osmotický tlak MeSH
- polyestery chemie MeSH
- teplota MeSH
- tranzitní teplota MeSH
- voda chemie MeSH
- Publikační typ
- časopisecké články MeSH
- MeSH
- adheziva * chemie MeSH
- estery kyseliny mravenčí MeSH
- farmaceutická chemie MeSH
- farmaceutická technologie MeSH
- hydrofobní a hydrofilní interakce MeSH
- kyselina mléčná MeSH
- kyselina polyglykolová MeSH
- nosiče léků * chemie MeSH
- polyestery * chemie MeSH
- reologie MeSH
- rozpouštědla MeSH
- rozpustnost MeSH
- sliznice MeSH
- uvolňování léčiv MeSH
- změkčovadla chemie MeSH
The study describes the detailed examination of the effect of ethylene oxide sterilization on electrospun scaffolds constructed from biodegradable polyesters. Different fibrous layers fabricated from polycaprolactone (PCL) and a copolymer consisting of polylactide and polycaprolactone (PLCL) were investigated for the determination of their mechanical properties, degradation rates and interaction with fibroblasts. It was discovered that the sterilization procedure influenced the mechanical properties of the electrospun PLCL copolymer scaffold to the greatest extent. No effect of ethylene oxide sterilization on degradation behavior was observed. However, a delayed fibroblast proliferation rate was noticed with concern to the ethylene oxide sterilized samples compared to the ethanol sterilization of the materials.
- MeSH
- biokompatibilní materiály chemie metabolismus farmakologie MeSH
- buněčné linie MeSH
- cévní protézy MeSH
- ethylenoxid chemie farmakologie MeSH
- mikroskopie elektronová rastrovací MeSH
- modul pružnosti MeSH
- myši MeSH
- nanovlákna chemie MeSH
- pevnost v tahu MeSH
- polyestery chemie metabolismus MeSH
- sterilizace MeSH
- viabilita buněk účinky léků MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Three commercially available biodegradable polymers, two different aromatic-aliphatic copolyesters and polylactic acid, intended for the fabrication of agricultural mulching films, in addition to other applications, were subjected to a series of tests with the aim of studying the relationship between their photooxidation and biodegradation. Photooxidation resulted in the rearrangement of polymeric chains, in the case of both copolyesters the events led to polymeric chain crosslinking and the formation of insoluble polymeric gel. The tendency was significantly more pronounced for the copolyester with the higher content of the aromatic constituent. As regards polylactic acid photochemical reactions were not accompanied by crosslinking but instead provoked chain scissions. A biodegradation experiment showed that, despite marked structural changes, the extent of photooxidation was not the decisive factor, which significantly modified the rate of biodegradation in all three materials investigated. The specific surface area of the sample specimens was shown to be more important.
The influence of biofilm formation as the mode of microorganism growth on degradation of synthetic polymers represents an important research topic. This study focuses on the effect of biofilm developed by Bacillus subtilis (BS) cultivated submerged under various nutrition conditions on biodeterioration of poly(ε-caprolactone) film. Polymer in the film form (thickness 0.7 mm) was incubated for 21 days either continuously or by regularly renewed system. The scission of polyester chain bonds took place in all biotic media and was enhanced by biofilm formation in nutrient-rich media.
Úvod: V chirurgii kýl břišní stěny jsou nejčastěji používány polyesterové a polypropylenové síťky. Jejich intraperitoneální implantace může vést k tvorbě adhezí s břišními útrobami s následnou poruchou pasáže nebo vznikem střevní píštěle. Některé kompozitní implantáty mohou snížit riziko tvorby adhezí. Cílem studie bylo posouzení vlastností a vhodnosti intraperitoneální implantace nového typu kompozitního materiálu, polyesterové síťky potažené tenkou vrstvou polyuretanu, v experimentu na laboratorním potkanu. Materiál a metoda: Experiment byl proveden na 21 laboratorních potkanech. Laboratorní zvířata byla rozdělena do 3 skupin po 7 jedincích. U první skupiny byla provedena kontrolní laparotomie 7. den, u druhé skupiny 14. den a u třetí skupiny 28. den po intraperitoneální implantaci kompozitní síťky. Byla posouzena tvorba adhezí s břišními útrobami a histologicky byly vyšetřeny vzorky tkání s implantovanou síťkou. Výsledky: Makroporózní polyesterová vrstva síťky podporovala časnou a mohutnou vazivovou proliferaci s dobrou adhezivitou k břišní stěně. Na druhé straně mikroporózní polyuretanová vrstva vedla k vytvoření vazivové kapsy. Při kontrolní laparotomii byly u většiny laboratorních potkanů ve všech skupinách nalezeny rozsáhlejší adheze omenta k vazivové vrstvě pokrývající polyuretanovou stranu implantované síťky. Závěr: Lze předpokládat, že ochranná polyuretanová vrstva nevylučuje riziko tvorby adhezí u laboratorního potkana.
Introduction: Polyester and polypropylene are currently the most frequently materials for repair of abdominal wall hernias. Most of the mesh materials used intraperitoneally in repair of hernias lead to considerable adhesion formation, as well as the resultant bowel obstruction and intestinal fistula formation. Some newer composite products can reduce risk of adhesion formation. The aim of this experimental study is testing properties of patch, composite structure, characterised by the association of a non-woven textile structure made from polyester multifilaments, and a fine coat of polyurethane on one side, placed intraperitoneally in rat. Materials and methods: The experiment was carried out with 21 laboratory rats. Laboratory animals were divided into 3 groups – 7 animals in a group. In the first group the check-up laparotomy was realized the 7th day, in the second group the 14th day and in the third group the 28th day after the intraperitoneal implantation of a composite mesh. All animals were sacrificed and adhesion scoring and histological evaluation of tissue specimens with implanted mesh were done. Results:Amacroporous polyester mesh component supported an early and huge fibrous proliferation with a good adhesion onto the abdomen wall. On the other hand, a microporous polyurethane layer led to the creation of a fibrous pocket. During the check-up laparotomy, the larger adhesion of omentum to the fibrous layer, covering the polyurethane side of implanted mesh, were located in most laboratory rats – in all the groups. Conclusion: We can presume that the protective polyurethane layer does not eliminate risk of adhesion formation in rat.
- MeSH
- adheze tkání MeSH
- chirurgické síťky využití MeSH
- experimentální implantáty trendy MeSH
- hernie MeSH
- krysa rodu rattus MeSH
- modely u zvířat MeSH
- operace kýly MeSH
- polyestery terapeutické užití MeSH
- polyurethany terapeutické užití MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- zvířata MeSH
- Publikační typ
- přehledy MeSH
- srovnávací studie MeSH
