Romina P. Ollier; Matias R. Lanfranconi; Vera A. Alvarez; Leandro N. Ludue
Abstract
In this work, biodegradable nanocomposites based on polycaprolactone (PCL) reinforced with 2.5, 5.0 and 7.5 wt.% of two different clays, a commercial organo-clay (Cloisite 20A, C20A) and a laboratory modified bentonite with tributylhexadecyl phosphonium bromide (bTBHP), were prepared by melt intercalation ...
Read More
In this work, biodegradable nanocomposites based on polycaprolactone (PCL) reinforced with 2.5, 5.0 and 7.5 wt.% of two different clays, a commercial organo-clay (Cloisite 20A, C20A) and a laboratory modified bentonite with tributylhexadecyl phosphonium bromide (bTBHP), were prepared by melt intercalation followed by compression molding. The study contemplates the analysis of chemical (Infrared Spectrometry, FTIR), morphological (X-Ray Diffractometry, XRD, Scanning Electron Microscopy, SEM, and Transmission Electron Microscopy, TEM), rheological, thermal (Differential Scanning Calorimetry, DSC, and Thermogravimetrical Analysis, TGA) and mechanical properties (tensile tests), which are important properties for packaging applications.In previous works, we concluded that higher clay dispersion degree inside the PCL matrix is expected when clays with large interlayer distance, strong hydrophobicity and strong processing stability are used. In the present work, the opposite result was obtained. Although the phosphonium treated clay (bTBHP) showed the largest interlayer distance (d001), strongest hydrophobicity and the best processing stability, the clay dispersion degree inside PCL was worse than in the case of the alkylammonium treated clay (C20A). PCL/bTBHP nanocomposites showed weaker mechanical properties in comparison with PCL/C20A ones, which is in accordance with the morphological analysis. On the other hand, the thermal properties of the matrix were not substantially affected by clay incorporation in both nanocomposites.
Romina P. Ollier*; Jimena S. Gonzalez;Vera A. Alvarez; Laura M. Sanchez
Abstract
Hydrogels are one of the most widely employed materials in biological, medical and technological areas. However, the use of hydrogels sometimes is restricted due to their specific properties. It is well-known that polymeric nanocomposites reinforced with clays show valuable improvements in their properties. ...
Read More
Hydrogels are one of the most widely employed materials in biological, medical and technological areas. However, the use of hydrogels sometimes is restricted due to their specific properties. It is well-known that polymeric nanocomposites reinforced with clays show valuable improvements in their properties. In this work, eco-friendly composite hydrogels were prepared employing polyvinylalcohol (PVA) and bentonite (abundant and low cost smectite-type clay in Argentina) as raw materials through the previously optimized freezing-thawing (F-T) crosslinking method. Different nanocomposite hydrogels were obtained by varying the corresponding reactor feed. These materials have been recently chemically, morphologically and mechanically analysed in a recent work. Specifically, in the present work, thermal degradation behaviour of PVA-bentonite hydrogels was studied. Kinetic analytical models were applied to non-isothermal thermogravimetric (TGA) measurements trying to identify the possible mechanism for PVA degradation in the presence of bentonite.
Jimena S. Gonzalez; Alejandra Ponce; Vera A. Alvarez
Abstract
During the last decade researchers have been working to find effective wound dressing materials. The materials have to be designed to hold moisture in the surface of the wound, providing the ideal environment for cleaning the wound, absorbing the exudates, eliminating the odour and promoting the healing ...
Read More
During the last decade researchers have been working to find effective wound dressing materials. The materials have to be designed to hold moisture in the surface of the wound, providing the ideal environment for cleaning the wound, absorbing the exudates, eliminating the odour and promoting the healing process. In this scenario, hydrogels emerge as excellent options for that. However, due to poor mechanical and antimicrobial properties of many conventional hydrogels, composite hydrogels are now designed in order to improve mechanical stiffness and durability. For this purpose, nanocomposite based on poly(vinyl alcohol) (PVOH) and different concentration of bentonite (0-7 wt.%) were obtained by the freezing-thawing technique and characterized by means of morphological, physical, thermal, mechanical, barrier and antimicrobial properties. Herein it was developed a non-expensive, eco-friendly and a facile method to obtain nanocomposite hydrogels based on PVOH with reasonable mechanical properties (Young Modulus of 0.5-0.8 MPa), good microbial barrier properties, adequate water vapour transmission rates and excellent swelling behaviour (195-336%). Moreover, it was found that the porous sizes of the samples can be controlled by the addition of the clay. All obtained results indicate that the PVOH/ 3% bentonite hydrogels show potential to be used as wound healing.
)
)