•Novel extruded films of polyethylene with a content of 20wt% chitosan were obtained.•Compatibilizer PEgMA and glycerol improved the processability of the mixtures.•The compatibilized films showed an ...improvement in the deformation at break.
Novel films of polyethylene and chitosan were obtained using extrusion. These polymers have interesting properties, and processing them with methods that are of high use in the industry, such as the extrusion method, can have a significant effect on the potential applications of these materials. The individual materials were thermally characterized; after this, extruded films of low density polyethylene and chitosan mixtures were prepared with the addition of polyethylene-graft-maleic anhydride as a compatibilizer for the blends, and glycerol, as a plasticizer for chitosan. The use of compatibilizer and plasticizer agents improved the processability and compatibility of the mixtures, as well as their mechanical properties, as revealed by mechanical property measurements and scanning electron microscopy. It was possible to prepare blends with a maximum chitosan content of 20wt%. The material stiffness increased with the increase of chitosan in the sample. FTIR studies revealed the existence of an interaction between the compatibilizer and chitosan.
Among the natural fibers, jute stands out for its characteristics. However, the adhesion between the fibers and the polymer matrix is limited and, therefore, physicochemical changes to the fiber ...surface are required. In this paper, the effects of physicochemical treatments on jute fibers were analyzed. We found alkaline treatment to be the most widespread and the use of chemical agents allows a greater addition of fiber to polymer matrices. Nevertheless, these treatments produce a lot of waste, increase the cost of production, and use toxic compounds. An environmentally friendly alternative is the application of irradiation to improve adhesion.
Optimal usage of urea-based fertilizers can increase their use efficiency and reduce pollution. A new alternative for prolonged-release (PR) urea based on wheat-gluten (WG) membranes obtained by ...electrospinning was studied. The effect of pH and temperature on the release rate of urea and its transport mechanisms were evaluated. At pH 4, 7, and 10, the equilibration times obtained were 1, 3, and 5 h, respectively. Additionally, at a higher temperature, a larger amount of urea was released into the medium. The Ritger–Peppas model suggests that with pH 4 and pH 10, at 25 °C, there is an anomalous diffusion mechanism. On the other hand, the remainder of the release conditions tested showed a release mechanism of urea by simple diffusion. According to the results, a potential application of these wheat-gluten membranes on the release system of urea for soils with pH 7 and soil temperatures between 25 and 40 °C is proposed.
Graphical Abstract
Novel hydrogels of interpenetrating polymer networks (IPNs) composed of polyacrylamide and poly(γ-glutamic acid) were synthesized. In these systems, both polymers were crosslinked independently; this ...reduced the potential loss of a polymer during the washing process, as often occurs in semi-IPN systems. Interpolymer interactions were investigated with Fourier transform infrared spectroscopy and differential scanning calorimetry. These studies suggested possible interactions between both polymers by the formation of hydrogen bonds. The swelling behavior of these hydrogels was analyzed by immersion of the hydrogel samples in deionized water at 25 and 37°C and in buffer solutions with pHs of 3, 7, and 10. The kinetics of swelling showed increases in the values of the swelling ratio with increasing immersion time in the swelling medium, molar proportion of the biopolymer in the hydrogel, temperature, and pH of the swelling medium. All of the hydrogels swelled rapidly and reached equilibrium in an average time of 40 min.
Development of microparticles based on natural polymers has been of interest for researchers due to their applications, such as release systems. Currently, one of the problems presented by ...agriculture worldwide is the loss of fertilizers, i.e., urea, causing environmental pollution and high costs. The aim of this work was to develop microparticles of wheat glutenins by means of electrospray technique, with potential application as a urea controlled-release system in agricultural soils. The microparticles of wheat glutenins were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA). In addition, a release kinetic test was performed to evaluate the possible behaviour of wheat-glutenin microparticles in agricultural soils with pH 4, 7 and 10, using buffers as the release medium. TGA indicated that microparticle stability was
>
100
∘
C
, while FT-IR demonstrated the existence of physical interactions between urea and wheat glutenins. The kinetic tests showed the possible behaviour of the controlled-release fertilizer at pH 4, 7 and 10; rapid release at acidic pH and a decrease in release time at basic pH. With these results, we can conclude that the urea-charged wheat-glutenin microparticles can function as a controlled-release fertilizer in agricultural soils.
Controlled drug release systems have the characteristics of eliminating or reducing side effects and producing a therapeutic concentration of the drug that is stable in the body. The synthesis of ...hydrogels from natural polymers allows innovation in new materials that promote more effective, selective and safe therapies, in comparison with hydrogel systems based on synthetic polymers where their main limitation may be their biocompatibility and degradation. For this reason, in this work the synthesis of hydrogels of chitosan crosslinked with glutamic acid is proposed as the basis of new trends in smart materials for their potential use in the controlled release of drugs, the hydrogels were prepared from an amidation reaction between the amino groups of chitosan and the carboxyl groups of
L
-glutamic acid, using
N
-(3-Dimethylaminopropyl)-
N
′-ethylcarbodiimide hydrochloride (EDC) as activator of the carboxyl groups. The hydrogels obtained were characterized by SEM, FTIR, TGA techniques, swelling kinetics and antimicrobial activity. They exhibited excellent swelling capacity and good performance when exposed to different pH and temperature conditions. The bacterial inhibition percentages demonstrated the antimicrobial activity of chitosan hydrogels and the results obtained potentially favored their use as reservoirs for controlled drug release.
In the present work, polylactic acid (PLA), elastin and gelatin fibers, containing clindamycin, were prepared to test their potential application as wound dressings. They underwent release studies to ...determine the mechanism of drug release through mathematical models. The fibers have a homogeneous morphology, without pores. The studies of FTIR and thermal analysis corroborate the presence of each of the components in the fibers; the results of the feasibility tests showed encouraging percentages with a viability of 82% after 7 days of direct contact of the HUVEC cells with the membranes. Similarly, cell adhesion assays show the presence of viable and stretched cells on the fibers, the tendency of the cells to position themselves on the fibers and follow this conformation was observed. On the other hand, studies of antimicrobial activity against
S. aureus
show us that in fibers loaded with clindamycin they have inhibition halos greater than 8 mm.
Polyethylene/poly (lactic acid)/chitosan films, with and without poly (ethylene-g-maleic anhydride) (PEgMA) as compatibilizer, were prepared by extrusion and the degradation behavior under different ...times of standard weathering conditions was analyzed. The materials were characterized by means of infrared spectroscopy, scanning electron microscopy, tensile strength, differential scanning calorimetry and thermogravimetric analysis. It was demonstrated that blends of synthetic and natural polymers have a higher susceptibility to degradation in comparison to neat polyethylene and poly (lactic acid) films. Additionally, it is found that the incorporation of PEgMA into the extruded films apparently favored the polymer degradation, as it deduced from the fall of the mechanical properties when the films are exposed to accelerated weathering simulation.
•Extruded polymeric blends of PE PLA Ch with and without compatibilizer were obtained.•The incorporation of PEgMA makes the films to have a larger degradation.•The accelerated degradation has a strong effect on the mechanical properties of the films.•Morphology of the films was greatly affected by accelerated weathering.•The compatibilizer has no significant effect on the thermic stability of the materials tested.
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•Novel electroconducting PPy/CNT/alginate nanocomposites were synthesized through in situ chemical polymerization in micellar media.•The method involves H2O2 and small amount of SDS ...as a green approach to form a three-dimensional structure with well-connected domains.•The synergistic combination of pristine CNT and alginate improves the conductivity and stability of PPy-based colloids.•A metoprolol-loaded platform was obtained by the confinement of the synthesized nanocomposite into an alginate network.•The hydrogel matrix produces a hindering effect on drug release in passive conditions.
The development of Green-based methods for preparing polypyrrole (PPy)-containing materials with optimal electroactivity still remains a challenge. We herein report a new green approach for the preparation of PPy/carbon nanotube/alginate multifunctional nanocomposites through H2O2 oxidation in micellar medium. The polymerization conditions were systematically varied to optimize the reaction yield and the material electroconductivity. The pre-polymerization emulsion system was studied by contact angle measurements and dynamic light scattering. The results of zeta potential characterization, field-emission scanning electron and atomic force microscopy, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and electrochemical impedance spectroscopy are discussed in detail, and a consistent mechanism for the nanocomposite formation is proposed. Interestingly, the synergistic combination of pristine carbon nanotubes and the alginate improves the conductivity and stability of PPy-based colloids. Furthermore, a metoprolol-loaded platform, obtained by the confinement of the synthesized nanocomposite into an alginate network, revealed a cumulative release lesser than 10% after five hours of delivery under passive conditions. This behavior seems to be promising to overcome the undesired burst release in stimulus-controlled drug delivery.
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