Graphene oxide-coated amino-modified polyacrylonitrile to fabricate highly conductive fabrics

Graphene conductive polyacrylonitrile (PAN) substrate is an important material, owing to its high strength, flexibility, and comfort. In this work, a PAN fabric was cationized with triethylene tetramine (TETA) for increased adsorption of anionic graphene oxide (GO), which mainly forms ionic bonds. The TETA-modified PAN (Amino-PAN) fabric was then treated with GO using a dipping method followed by in situ reduction of GO to obtain reduced graphene oxide (RGO). The electric conductivity of Amino-PAN fabrics was increased with the increasing of TETA modification temperature from 90°C to 110°C. A surface electric resistance of 0.61 kΩ cm−1 was obtained for 2 g L−1 GO and TETA modification performed at 110°C for 2 h. This resistance was considerably lower than that of the original PAN fabric for one cycle of the dipping–reduction GO treatment (1RGO-PAN, 42.69 kΩ cm−1) and six cycles of the dipping–reduction GO treatment (6RGO-PAN, 1.52 kΩ cm−1). The results revealed that the anionic GO was more easily adsorbed on the surface of the Amino-PAN fabrics than on the original PAN fabrics. The surface electric resistance of the 1RGO-Amino-PAN fabrics slightly increased from 0.61 to 0.79 kΩ cm−1 after 30 washing cycles. The results showed that the RGO-coated Amino-PAN fabric had excellent washability. Furthermore, the TETA modification process reduced the dipping–reduction times of the GO finishing PAN fabrics, and can be easily used in the production of RGO-based flexible conductive material.

Melting and Recrystallization of Copper Nanoparticles Prepared by Microwave-Assisted Reduction in the Presence of Triethylenetetramine

The small sized copper nanoparticles (Cu-NPs), prepared in the presence of triethylene tetramine (TETA) and assisted with microwave irradiation, have an extremely low melting temperature. Melting of the small sizezd Cu-NPs can be triggered by the heat generated from the e-beam irradiation during SEM and TEM image construction. The dispersed Cu atoms around the agglomerated big Cu particles can undergo recrystallization immediately due to the strong driving force of the huge temperature difference to normal melting temperature (Tm = 1085 °C). Some of the Cu-NPs with bigger sizes also recrystallize and agglomerate into dense, big particles. According to X-ray diffraction patterns, these particles can agglomerate into compact, ordered Cu crystals in less than five minutes at 60 °C. The melting and recrystallization related endothermic and exothermic phase transitions of Cu-NPs can be found from differential scanning calorimeter (DSC) thermograms and optical microscopic pictures.

THERMOPLASTIC VULCANIZATES BASED ON DYNAMICALLY VULCANIZED POLYPROPYLENE/CARBOXYLATED NITRILE RUBBER BLENDS

ABSTRACT Thermoplastic vulcanizates (TPVs) based on polypropylene (PP) and carboxylated nitrile rubber (XNBR) with improved mechanical properties were prepared by dynamic vulcanization using dicumyl peroxide (DCP) in combination with N,N′-m-phenylene-bis-maleimide (BMI) as a cross-linking system. The effect of PP grafted with maleic anhydride (PP-g-MA) or with glycidyl methacrylate (PP-g-GMA) and triethylene-tetramine (TETA) as the compatibilizing systems on the mechanical, morphological, and dynamic mechanical properties of PP/XNBR blends was investigated. Experimental results revealed that PP-g-GMA has a better compatibilizing efficiency. Tensile strength and elongation at break presented a significant improvement with the addition of 2.5 to 7.5 phr of this functionalized PP. The improvement of the tensile properties was observed for all blend compositions studied. Also the tensile properties of the blends did not change considerably after three reprocessing cycles, confirming the efficiency of this system as a TPV. The presence of PP-g-GMA also resulted in an increase of the apparent melt viscosity of the corresponding TPVs, confirming the reactive compatibilization. A decrease in rubber particle size with the presence of PP-g-GMA was also observed by scanning electron microscopy.

Self-emulsified waterborne epoxy hardener without acid neutralizers and its emulsifying and curing properties

Purpose The purpose of this study is to prepare a new self-emulsified waterborne epoxy hardener which can emulsify the liquid epoxy resin in aqueous media without addition of acid neutralizers. Design/methodology/approach Two synthetic steps were adopted to prepare novel self-emulsified amine-epoxy adduct type hardener composition based on the reaction of a commercially available polyetheramine, bisphenol A epoxy resin and triethylene tetramine. The different factors affecting the synthesis of the waterborne epoxy hardener were explored by emulsifying and curing properties. The process and products were analyzed and confirmed by FIRT. Findings Compared to an introduction of polyether as a hydrophilic segment in previous literature, whose reaction required Lewis acid catalysts and strict control of the presence of water, the introduction of polyetheramine to obtain a novel self-emulsified waterborne epoxy hardener were concise and convenient by mere two amine-epoxy addition steps in this research. Moreover, the final product offered good film formation with a practical value of mechanical properties, glass transition temperature and water-resistant property. Practical implications The self-emulsified waterborne epoxy hardener can be used to prepare water-resistant waterborne coatings from liquid epoxy resins while also providing the option of zero VOC formulations. Originality/value Introduction of hydrophilic polyether amine to prepare self-emulsified waterborne epoxy hardener without acid neutralizers has not been systematically studied previously.

Application of Enriched Fraction of Seabuckthorn Leaf Extract as Antimicrobial Finish on Technical Textile

<p class="p1">Flavonoid-rich fraction (FRF) from Seabuckthorn leaves extract was prepared by acid hydrolysis process. Total flavonoid content of Seabuckthorn leaves extract and FRF estimated as rutin equivalent was found to be 116.98±3.06 and 277.14 ± 6.78 mg/g of extract/FRF respectively. Its major constituents myrcetin, quercetin, kaempferol and isorhamnetin, were determined by reverse phase high performance liquid chromatography (RP-HPLC). Aramid (NomexIIIA) fabric was treated with triethylene tetramine to increase the wicking height of the fabric for better uptake of FRF. Then, FRF was coated using citric acid as cross linking agent on to aramid fabric by pad-dry-cure method for improved wash durability. FRF coated fabric was characterised using Universal attenuated total internal reflection Fourier Transform Infrared spectroscopy. Effect of FRF coating on flammability property of coated fabric was estimated using flammability tester. There was no significant difference in the char length of the FRF coated fabric and control samples.<span class="Apple-converted-space"> </span></p><p class="p2">Antimicrobial activity of the FRF coated fabric was assessed by both qualitative (agar diffusion method; AATCC 147-2001) and quantitative (percentage reduction test; (AATCC 100-2001) methods using test organisms. The zone of inhibition by agar diffusion method for <em>E. coli </em>and <em>S. aureus </em>was found to be 12.4 mm and 16.7 mm respectively. Quantitative assessment by percentage reduction test showed a reduction percentage of 96.00% and 93.00% for <em>S. aureus </em>and <em>E</em>. <em>coli</em>, respectively. The results of the above study indicate FRF as a valuable ingredient for the development of antimicrobial textiles.</p>