Research

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11812 KiB

Open AccessArticle

Thermal Treatment of Melt-Spun Fibers Based on High Density PolyEthylene and Lignin

by Panagiotis Goulis, Giorgos Konstantopoulos, Ioannis A. Kartsonakis, Konstantinos Mpalias, Stavros Anagnou, Dimitrios Dragatogiannis and Costas Charitidis

C 2017, 3(4), 35; https://doi.org/10.3390/c3040035 - 13 Nov 2017

Cited by 6 | Viewed by 4979

Abstract

The purpose of this study was the synthesis of novel low-cost carbon fibers along with the investigation of the optimal parameters of temperature and time for the stabilization of hybrid high-density polyethylene (HDPE) and lignin melt-spun fibers. These fibers were manufactured by physical [...] Read more.

The purpose of this study was the synthesis of novel low-cost carbon fibers along with the investigation of the optimal parameters of temperature and time for the stabilization of hybrid high-density polyethylene (HDPE) and lignin melt-spun fibers. These fibers were manufactured by physical compounding of HDPE and chemically-modified softwood kraft lignin (SKL) in order to produce green fiber precursors for carbon fiber synthesis. Stabilization tests were performed with respect to thermal treatment (physical method) and sulfonation treatment (chemical method). The results revealed that only chemical methods induce the desired thermal process-ability to the composite fibers in order to manufacture carbon fibers by using a simple method. This investigation shed light on the stabilization techniques of polymeric fibers in the absence of any cyclic groups in terms of environmentally-friendly mass production of carbon fibers using low-cost and green raw materials. This study facilitates incorporation of softwood lignin in homegrown polymeric fibers by a low-cost production process via melt-spinning of composite fibers, which were successfully stabilized using a facile chemical method and carbonized. Additionally, a comprehensive investigation of the thermal behavior of the samples was accomplished, by examining several ways and aspects of fiber thermal treating. The properties of all studied fibers are presented, compared, and discussed. Full article

(This article belongs to the Special Issue Chemical Bond Formation for Nanocarbon-Based Composites)

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3922 KiB

Open AccessArticle

DFT Study on the Interaction of the Smallest Fullerene C₂₀ with Lithium Ions and Atoms

by Hiroshi Kawabata and Hiroto Tachikawa

C 2017, 3(2), 15; https://doi.org/10.3390/c3020015 - 10 May 2017

Cited by 9 | Viewed by 5488

Abstract

The smallest fullerene C₂₀ with positive electron affinity is considered to be a new organic nano-electronic material. The binding structures and electronic states of lithium ions and atoms (Li⁺ and Li) trapped on the surface of C₂₀ have been investigated [...] Read more.

The smallest fullerene C₂₀ with positive electron affinity is considered to be a new organic nano-electronic material. The binding structures and electronic states of lithium ions and atoms (Li⁺ and Li) trapped on the surface of C₂₀ have been investigated by means of density functional theory (DFT) calculation to elucidate the nature of their interaction. It was found that a Li⁺ can bind to only one site of C₂₀. This is, specifically, on top of the site where Li⁺ binds to the carbon atom of C₂₀. On the other hand, in the case of a Li atom, two structures were obtained besides the on-top structure. One was pentagonal structure which included a Li atom on a five-membered ring of C₂₀. The other was a triangular structure in which the Li atom bind to the the carbon–carbon bond of C₂₀. Finally, the nature of the interactions between Li ions or atoms and the C₂₀ cluster was discussed on the basis of theoretical results. Full article

(This article belongs to the Special Issue Chemical Bond Formation for Nanocarbon-Based Composites)

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Review

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1839 KiB

Open AccessReview

Graphene–Noble Metal Nano-Composites and Applications for Hydrogen Sensors

by Sukumar Basu and Surajit Kumar Hazra

C 2017, 3(4), 29; https://doi.org/10.3390/c3040029 - 13 Oct 2017

Cited by 20 | Viewed by 5973

Abstract

Graphene based nano-composites are relatively new materials with excellent mechanical, electrical, electronic and chemical properties for applications in the fields of electrical and electronic devices, mechanical appliances and chemical gadgets. For all these applications, the structural features associated with chemical bonding that involve [...] Read more.

Graphene based nano-composites are relatively new materials with excellent mechanical, electrical, electronic and chemical properties for applications in the fields of electrical and electronic devices, mechanical appliances and chemical gadgets. For all these applications, the structural features associated with chemical bonding that involve other components at the interface need in-depth investigation. Metals, polymers, inorganic fibers and other components improve the properties of graphene when they form a kind of composite structure in the nano-dimensions. Intensive investigations have been carried out globally in this area of research and development. In this article, some salient features of graphene–noble metal interactions and composite formation which improve hydrogen gas sensing properties—like higher and fast response, quick recovery, cross sensitivity, repeatability and long term stability of the sensor devices—are presented. Mostly noble metals are effective for enhancing the sensing performance of the graphene–metal hybrid sensors, due to their superior catalytic activities. The experimental evidence for atomic bonding between metal nano-structures and graphene has been reported in the literature and it is theoretically verified by density functional theory (DFT). Multilayer graphene influences gas sensing performance via intercalation of metal and non-metal atoms through atomic bonding. Full article

(This article belongs to the Special Issue Chemical Bond Formation for Nanocarbon-Based Composites)

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