Biodegradable polymers: A review about biodegradation and its implications and applications

Plastic waste pollution is a global environmental problem that could be solved by biodegradable materials. In addition, its biodegradability has been important for medical applications. In this way, the biodegradability performance has been investigated for different materials under diversified environmental conditions. In this context, this review shows the main up-to-date biodegradable polymers (from renewable sources and fossil-based), their structure and properties, and their biodegradability characteristics. Also, this review shows the effect of polymer properties and environmental conditions on biodegradability, methods of biodegradability and toxicity determination, modification processes to enhance biodegradability, and main applications of biodegradable polymers for agriculture, medical, and packaging. Finally, this review presents a discussion of the implications of biodegradation on the environment, the current context, and future perspectives of plastic biodegradation.     

Asymmetric oxygen-functionalized carbon nanotubes dispersed in polysulfone for CO2 separation

Carbon dioxide separation from flue gases is an important challenge to be faced. Membrane processes are a promising alternative to increase technical and economical constraints once the development of materials with superior characteristics are attained. Integrally asymmetric mixed matrix membranes (MMMs) were prepared by dry/wet phase inversion process of polysulfone (PSF) containing oxygen-functionalized multiwalled carbon nanotubes (MWNT-O). Fourier transform infrared (FTIR) spectroscopy confirmed the presence of MWNT-O in MMMs. Thermal gravimetric analysis (TGA) showed that MMMs are stable up to 150°C. Photomicrographs from scanning electron microscopy (SEM) revealed that MMMs consist of an asymmetric structure with a skin layer supported on a sponge-like substructure. The pore size of the support of MMMs increased with MWNT-O content from 0.4 to 0.8 wt.% and the thickness of the dense layer decreased. However, when the content of MWNT-O increased to 1 wt.%, the pore size decreased, and the dense layer increased. Therefore, MMMs changed CO₂ separation performance. For 1 wt.% MWNT-O loading compared to the neat polymer, CO₂ permeance and CO₂/N₂ selectivity was increased from 1.5 to 2.7 GPU, and from 9.5 to 14.3, respectively.