Abstract This work presents the results obtained in the production of poly (vinyl alcohol) (PVA) nanofibers with different concentrations of polypyrrole (PPy) doped with dodecylbenzene sulfonic acid (DBSA) - PPy.DBSA. The morphology of the nanofibers was studied by scanning electron microscopy (SEM) technique. The nanofibers were deposited on interdigitated electrodes (IDEs) for direct current electrical characterization (DC) and tested as ammonia gas sensors. The results showed a rapid detection of ammonia gas for higher concentrations of PPy.DBSA and for several alternating cycles in atmospheric N2.

Abstract There is a great demand to develop different techniques for the continuous removal, immobilization, and remediation of metallic ions from contaminated water. Human contamination by metallic ions could even occur by ingestion of seafood causing carcinogenic and mutagenic activities. In this study, a nanofibrous membrane of poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) produced by electrospinning technique and coated with polyaniline (PAni) was tested for the removal of chromium in low-concentration solutions. The viability of ZFL cells (zebrafish liver cells) was performed to evaluate the water quality enhancement after chromium adsorption. The results indicated that the nanofibrous membrane successfully adsorbed the chromium species in low-concentration ( Q e= 2.44 mg/g, at pH 4.5, room temperature (RT) and 24h) by Freundlich model and followed a pseudo-second-order kinetics model indicating a possible chemisorption in multilayers, at pH 4.5, RT and [CrVI] = 5.0 mg/L. At pH 2.0 (24h, RT and [CrVI] = 5.0 mg/L), the membrane adsorbed around 91.64% of CrVI contaminants. The thermodynamic studies revealed that the process was spontaneous and exothermic. The cells viability demonstrated the efficiency of the membrane tested in the aquatic ecosystem protection; the viability increased 19.2% in 5.0 mg/L CrVI solution. Thus, the results of this study shows that the nanofibrous membrane can be an alternative to remove low concentration of CrVI from aqueous solutions.

ABSTRACT In recent years, the technique of electrospinning has been used to develop a novel class of micro- and nanoscale materials based on fibrous structures. Several polymers, in particular elastomers, that have been implemented in this process rely on properties such as elasticity, flexibility, biocompatibility, and low cost. Herein, we describe for the first time the electrospinning of natural rubber fibers without polymeric matrix to obtain self-standing non-woven mats and oriented elastomeric fibers. The fibers average diameters were approximately 5.5 µm. Polyaniline (PAni) was deposited on the membrane surface in order to enhance the conductive properties making easy the charge transportation. We have obtained biocompatible and flexible fibrous materials using natural rubber, this research opens up possibilities of using micro and nanofibers of only-natural rubber in many applications including sensors preparation.

Abstract A growing global trend for maximum use of natural resources through new processes and products has enhanced studies and exploration of renewable natural materials. In this study, cardanol, a component of the cashew nut shell liquid (CNSL), was used as a building block for the development of a thermosetting matrix, which was reinforced by raw and modified sponge gourd fibers (Luffa cylindrica). DSC and TG results showed that among biocomposites, the one reinforced by sponge gourd fibers treated with NaOH 10 wt% (BF10) had the highest thermal stability, besides the best performance in the Tensile testing, showing good incorporation, dispersion, and adhesion to polymer matrix, observed by SEM. After 80 days of simulated soil experiments, it has been discovered that the presence of treated fiber allowed better biodegradability behavior to biocomposites. The biobased thermoset plastic and biocomposites showed a good potential to several applications, such as manufacturing of articles for furniture and automotive industries, especially BF10.

Waste recycling has been the subject of numerous scientific researches regarding the environmental care. This paper reports the redirecting of sugarcane bagasse ash (SBA) as new filler to natural rubber (NR/SBA). The NR/SBA composites were prepared using an opened cylinder mixer to incorporate the vulcanization agents and different proportions of residue (SBA). The ash contains about 70-90% of inorganic compounds, with silica (SiO2) being the main compound. The SBA incorporation improved the mechanical properties of the vulcanized rubber. Based on these results, a new use is proposed for the agro-industry organic waste to be implemented in the rubber vulcanization process, aimed at improving the rubber physical properties as well as decreasing the prices of natural rubber composites.