Electrically conductive electrospun polymeric mats for sensing dispersed vegetable oil impurities inwastewater

This paper addresses the preparation of electrically conductive electrospun mats on a base of styrene-isoprene-styrene copolymer (SIS) and multiwall carbon nanotubes (CNTs) and their application as active sensing elements for the detection of vegetable oil impurities dispersed within water. The most uniform mats without beads were prepared using tetrahydrofuran (THF)/ dimethyl formamide (DMF) 80:20 (v/v) as the solvent and 13 wt. % of SIS. The CNT content was 10 wt. %, which had the most pronounced changes in electrical resistivity upon sorption of the oil component. The sensors were prepared by deposition of the SIS/CNT layer onto gold electrodes through electrospinning and applied for sensing of oil dispersed in water for 50, 100, and 1000 ppm. - 2019 by the authors.This publication was supported by the Qatar University Collaborative Grant QUCG-CAM-19/20-2. The findings achieved herein are solely the responsibility of the authors. The publication of this article was funded by the Qatar National Library.Scopu

Thermal and structural response of in situ prepared biobased poly(ethylene 2,5-furan dicarboxylate) nanocomposites

Poly(ethylene 2,5-furan dicarboxylate) (PEF) is considered the biobased counterpart of the fossil based poly(ethylene terephthalate) for food packaging. In this research, PEF nanocomposites containing 2.5 wt% neat multi walled carbon nanotubes (MWCNTs), or functionalized MWCNTs or graphene oxide (GO), were in situ prepared by applying the melt polycondensation method. The nanocomposites showed faster crystallization rates compared to the pristine material as proved by both differential scanning calorimetry (DSC) and polarized light microscopy (PLM). The latter evidenced an increased nucleation density in nanocomposites, due to the nucleating efficiency of the fillers, resulting in smaller spherulite size. However, a slightly reduced thermal stability was revealed for the nanocomposites by thermog-ravimetric analysis (TGA), especially in the case of GO-containing samples. The solid structure of the materials was studied by performing real time X-ray diffraction (XRD) measurements. In neat PEF, beta-crystals were observed in the solvent treated sample, while alpha-crystals were formed on cooling from the melt or cold-crystallization. On the contrary, in the XRD patterns of the nanocomposites only peaks associated with the alpha-crystal phase were found. Last, but not least, the effect of recrystallization on the thermal behavior was evaluated by means of modulated temperature DSC (MDSC). (C) 2016 Elsevier Ltd. All rights reserved

Aligned carbon nanotube–epoxy composites: the effect of nanotube organization on strength, stiffness, and toughness

10.1007/s10853-016-0228-6Journal of Materials Science512210005-1002

Morphology and Thermal Properties of Expanded Graphite (EG)/Poly(ethylene terephthalate) (PET) Nanocomposites

Uzyskano nanokompozyty poli(tereftalanu etylenu) z ekspandowanym grafitem (PET/EG) o zawartości nanonapełniacza 0.025 - 0.4 %wag. metodą polimeryzacji kondensacyjnej (polikondensacji) in situ. Określono ich morfologię (SEM i TEM), stabilność termiczną przy wykorzystaniu metody TGA (temperatury odpowiadające: 2% (T-2%),10% (T-10%) i 50% (T-50%) ubytku masy, energię aktywacji metodą Freemana-Carrolla (Ea), temperaturę maksimum szybkości ubytku masy nanokompozytów w atmosferze powietrza i w argonie. Oceniono również wpływ grafenu na przemiany fizyczne zachodzące w PET (DSC). Wyniki badań nanokompozytów PET/EG porównano z wynikami badań niemodyfikowanego PET. Fotografie SEM nanokompozytów wykazują dwufazową strukturę układów PET/EG z wyraźnie widocznymi płytkami grafenu, jak i nielicznymi aglomeratami. Badania nanokompozytów PET/EG z wykorzystaniem techniki TEM potwierdziły obecność płytek grafenowych o wielkości ok. 1-10 ?m. Oznacza to, że zastosowana metoda in situ pozwala na otrzymanie rozsuniętych i stosunkowo równomiernie rozłożonych płytek grafenowych (EG) w osnowie PET. Ponadto wykazano, że dodatek nanonapełniacza nie wpływa znacząco na temperatury przemian fizycznych, jak również na stopień krystaliczności PET. Zaobserwowano natomiast wyższą termostabilność oraz stabilność termo-oksydacyjną nanokompozytów wynikającą z udziału nanocząstek grafenowych.Nanocomposites based on poly(ethylene terephtalate) and expanded graphite (PET/EG) with 0.025-0.4wt.% nanofiller content were prepared by in situ condensation polymerization (polycondensation). Their morphology was determined (TEM, SEM), thermal stability by TGA (temperatures corresponding to: 2% (T-2%),10% (T-10%) and 50% (T-50%) weight loss, activation energy by Freeman-Carroll method (Ea), temperature of maximum mass loss rate of nanocomposites in air and in argon. Also the influence of graphene was assessed on the physical transition occurring in the PET (DSC). The results of PET/EG nanocomposites were compared with the unmodified PET. SEM images of nanocomposite exhibit a diphasic structure of PET / EG of clearly visible graphene platelets, and few agglomerates. The study of nanocomposites of PET / EG using TEM techniques confirmed the presence of grephene platelets size of about 1÷10 ?m. This means, that in situ polymerization has been used to obtain exfoliated and relatively evenly spaced graphene plates (EG) in the PET matrix. In addition, it was demonstrated that the addition of nanofiller not significantly affect the physical transition temperature, as well as the degree of crystallinity of PET. Higher thermal stability and thermo-oxidative stability of the nanocomposites was observed resulting from participation of graphene nanoparticles

Electrospun Copolyamide Mats Modified by Functionalized Multiwall Carbon Nanotubes

In this article, we report the preparation and properties of electro-conductive mats based on the commercial copolyamide (Vestamelt X1010) and multiwall carbon nanotubes functionalized by amino groups. Vestamelt X1010 is easily soluble in n-propanol at room temperature up to a concentration of 18 wt%. This is a significant advantage of this system because n-propanol is considered to be a safe and relatively environmentally friendly solvent compared with the organic solvents and acids frequently used for electrospinning of common synthetic polymers. The co-polyamide nanofibers were modified by multiwall carbon nanotubes grafted by amino groups to enhance their electrical conductivity at low filler content. The percolation threshold was found to be 0.33 vol%. Some applications of these mats were demonstrated such as the capability for sensing a selected vapor (acetone) and for oil/water separation. It was shown that neat Vestamelt X1010 mats remove around 85 wt% of oil (100 ppm of vegetable oil dispersed in water), whereas the addition of 1 wt% of CNTs enhances this ability up to 95 wt%. POLYM. COMPOS., 40:E1451-E1460, 2019.This work was made possible by NPRP grant No.: 7-1724-3-438 from the Qatar National Research Fund (A Member of the Qatar Foundation).Scopu

Size effects of graphene nanoplatelets on the properties of high-density polyethylene nanocomposites: Morphological, thermal, electrical, and mechanical characterization

High-density polyethylene (HDPE)-based nanocomposites incorporating three different types of graphene nanoplatelets (GnPs) were fabricated to investigate the size effects of GnPs in terms of both lateral size and thickness on the morphological, thermal, electrical, and mechanical properties. The results show that the inclusion of GnPs enhance the thermal, electrical, and mechanical properties of HDPE-based nanocomposites regardless of GnP size. Nevertheless, the most significant enhancement of the thermal and electrical conductivities and the lowest electrical percolation threshold were achieved with GnPs of a larger lateral size. This could have been attributed to the fact that the GnPs of larger lateral size exhibited a better dispersion in HDPE and formed conductive pathways easily observable in scanning electron microscope (SEM) images. Our results show that the lateral size of GnPs was a more regulating factor for the above-mentioned nanocomposite properties compared to their thickness. For a given lateral size, thinner GnPs showed significantly higher electrical conductivity and a lower percolation threshold than thicker ones. On the other hand, in terms of thermal conductivity, a remarkable amount of enhancement was observed only above a certain filler concentration. The results demonstrate that GnPs with smaller lateral size and larger thickness lead to lower enhancement of the samples' mechanical properties due to poorer dispersion compared to the others. In addition, the size of the GnPs had no considerable effect on the melting and crystallization properties of the HDPE/GnP nanocomposites. © 2020 Evgin et al.This work was partially supported by the Science Grant Agency VEGA, project no. 2/0010/18, and 2/0093/16 (Slovakia).2/0010/18, 2/0093/1