Browsing by Subject "Triboelectricity"

Now showing 1 - 7 of 7

Open Access
Charge dissipation mechanism of low-cost antistatic additive lignin in contact charged polymers
(2019-07) Özel, Mertcan
Contact electrification (C.E.), a phenomenon studied for millennia, develops contact charges on material surfaces, when two materials are contacted and then separated. Accumulation of contact charges and their uncontrolled sudden discharges on dielectric polymers pose major drawbacks in industries i.e. pharmaceutical, (micro)electronics, and space, causing million-dollar losses annually. The overall mechanism of C.E. is unclear until now, however, recent efforts have proven that chemical bond-breakages on polymer surfaces result in mechanoions – which are indeed the contact charges on the surfaces. These studies also showed that removing mechanoradicals (co-formed upon bond-breaking) by molecular radical scavengers destabilizes the mechanoions (charges) and render the doped polymer material antistatic. This method of static charge mitigation has an advantage over the conventional methods (e.g. doping with metals, carbon powder, conductive polymers, or surface humidity enhancers) because it is not based on an increase in surface conductance and smaller doping concentrations are needed to achieve antistatic behavior. However, currently used molecular radical scavenger doping is generally not cost effective method to be upscaled for industrial use. Lignin; however, is a “low-cost” material (the second most abundant polymer on earth, a by-product of paper production) that can act as a radical scavenger. In this thesis work, lignin was extracted from some examples of both hard and softwood. Firstly, it was verified that lignin doping in low concentrations (1 – 5% w/w) reduce the contact charge accumulation on common polymers such as on a crosslinked elastomer polydimethylsiloxane, and on thermoplastics polypropylene, polyethylene, polylactic acid, and polystyrene. Then, the mechanism of the observed charge dissipation was discussed in the light of the results obtained from surface conductance of polymers upon doping, 31P NMR and solid state 13C-NMR spectroscopy, total phenol content, and the reacted number of radicals before and after grinding - which was shown essential to get homogeneous doping- of lignin. The results pointed out a mechanism involving a radical scavenging activity without any change in the surface conductance of the material, similar to that with molecular radicals. The understanding of lignin’s charge dissipation mechanism will be helpful in industrial utilization of lignin as an antistatic additive and in assessment of the limitations of this utilization.
Open Access
Continuous triboelectric power harvesting and biochemical sensing inside poly(vinylidene fluoride) hollow fibers using microfluidic droplet generation
(Wiley-Blackwell, 2016-11) Kanik, M.; Marcali, M.; Yunusa, M.; Elbuken, C.; Bayındır, Mehmet
Triboelectric power harvesting and biochemical sensing inside poly(vinylidene fluoride) hollow fibers. Fiber‐based microfluidic energy harvesting system, which is also utilized as self‐powered chemical and biosensor. In vitro device concept demonstrating that triboelectric effect can be used for cell detection.
Open Access
Effect of triboelectric charges on friction and wear of polymers at macro scale
(2017-12) Sayfidinov, Khaydarali
The interest towards the study of underlying mechanism behind tribology has gained enormous attention recently since almost one-fourth of the total produced global energy is consumed by friction and wear. Dry sliding or rubbing two dielectric polymers on each other results in surface charging showing significant effects on friction coefficients and wear. Determination of the correlation between triboelectricity and tribologic events like friction and wear, the control of friction coefficient, and reducing wear by surface charging constitutes the main idea and research topic of this thesis. However, tribological events are very complicated considering the fact that diverse processes encompassing of physical and chemical changes occur at the counterface. Therefore, the fundamentals of friction is still controversial. Owing to tribological actions that occur due to contact between different phases of the matter, interfaces generate tribocharges due to electron, ion, and material transfer mechanisms. Even though the fundamental mechanism is still vague and under debate, it is believed that static electrification due to tribological actions are utterly because of electron transfer. Current studies unveiled that physical based phenomena are not the only source of surface electrification but also chemical changes such as bond rupturing and following surface oxidation that can take place as a result of mechanical actions on an insulating polymer. Consequently, these two groups of surface events; surface electrification and friction are expected to demonstrate a mutual relation, and detailed study concerning this relation needs to be investigated in order to solve e.g. energy loss and wear problems in tribology. To achieve this goal, it is essential to understand the main mechanisms and processes involved, and reveal the connections between tribological events and establish a relationship between all the intrinsic and extrinsic properties of materials from molecular, nano to meso scale. Thus, in this study, we investigated the contribution of triboelectrification to friction by taking into account some factors - surface area, load, atmosphere - between common polymers and pure cellulose under dry friction conditions.
Open Access
Mechanism of triboelectricity: a novel perspective for studying contact electrification based on metal-polymer and polymer-polymer interactions
(2016-08) Musa, Umar Gishiwa
The static electricity that is generated when two identical or different materials come in contact with each other and separated is a well known physical phenomenon that has been studied for over 25 centuries. Contact charging occurs in technological and natural aspects of our everyday life. Generation of lightning and the feeling of unexpected shocks on dry days are excellent examples of naturally occurring phenomenon, while in technology it is used for photocopying and laser printing. Owing to the increase in energy consumption around the globe and demand for carbon emissions free energy sources, the triboelectric effect has recently being utilized as an e ffective means of harvesting mechanical energy and converting it into electricity for novel applications like powering portable electronic devices and self powered active sensing. Despite the fact that it has been known and applied for many years, the fundamental mechanism of contact electrification is still not fully understood. This study proposes a mechanism for triggering such triboelectric charge based on polymer-polymer and metal-polymer interactions. Conventionally, the mechanism of electrostatic charge generation is being presumed as a process giving rise to a combination of positive (arising from contact) and negative (arising from separation) charges in every single contact and separation. However, in our mechanism we propose a concept that shows combination of both positive and negative charges as \contact" and either positive or negative charge, depending on the initial contact-charge polarity of the material (due to surface charge mosaic), as \separation" charge. Different kinds of polymers like polydimethylsiloxane (PDMS), polytetra uoroethylene (PTFE), Polyethersulfone (PES) and polypropene (PP) were used in this study and similar characteristic was observed for all of the polymers. Thus, our perception of the working principle of triboelectri cation between two dielectric materials or a metal and a dielectric material is consistent and potentially vital in comprehending some unresolved controversies on triboelectricity.
Open Access
Nanostructured materials and devices for sensing and energy harvesting applications
(2015-08) Kanık, Mehmet
A closer look into the fundamental challenges of the modern world reveals that the increasing demand for energy threatens the evolution of science and technology. Energy-efficiency is thus a fundamental issue in engineering nano-devices. An important path to achieve high efficiency is to convert the mechanical energy into electrical energy using piezoelectric and triboelectric energy harvesting circuitries, hence enabling self-powered systems at nanoscale. The utilization of novel piezoelectric and triboelectric energy harvesting materials introduces the opportunity of manufacturing flexible, wearable and stretchable self-powered devices. In this thesis, we introduced a new fabrication technique, new strategies and practical approaches for developing high performance triboelectric and piezoelectric materials and devices for flexible electronics, artificial skin and energy harvesting applications. The first part of the thesis focuses on the development of piezoelectric nanoribbons. Poly (vinylidene fluoride) and its copolymer Poly (vinylidene fluoride)-co-tri (fluoroethylene) were used to fabricate spontaneously high piezoelectric nanoribbons. We measured the record-high piezoelectric charge coefficient from our ribbons, because the high stress and high temperature used in the fabrication can enhance their properties. In addition, proof of principle devices for energy harvesting and sensing were fabricated using nanoribbons. The achievements in this part of the thesis can be listed as: i) We obtained extraordinary high aspect ratio, globally oriented, polymer encapsulated, and high piezoelectric microribbon and nanoribbon arrays. ii) Due to process conditions (shear stress and temperature) used in thermal fiber drawing, as-produced micro and nanoribbons contain high amount of polar phase without requiring any electrical poling. iii) We developed a new technique for characterizing and analyzing multiferroic characteristics of nano-objects, which consist of parallel evaluation of instrumental, numerical and analytical data. iv) To our knowledge, we achieved the highest piezoelectric charge coefficient from our ribbons in the literature. v) We enhanced stability of the piezoelectric ribbons by increasing the Curie temperature above its melting point due to processing conditions. vi) We observed and explained a new phase transformation mechanism in polymer piezoelectric ribbons. vii) The state-of-the-art ab initio calculations, which explain the phase transformation mechanism of molecules during the fiber drawing with the effect of shear, tensile forces and temperature, were included in detail. The second part is about developing high energy output triboelectric generators. A high performance multi-layered triboelectric generator was developed using chalcogenide nanostructures. This part of the thesis details the following achievements: i) We demonstrated that not only polymer, but also semiconductor chalcogenide materials can be used in triboelectric applications, for the first time. ii) For the first time, we proposed and demonstrated that the fluorination of nanostructured surfaces increases triboelectric performance significantly. iii) We introduced a multi-layered triboelectric generator which is very promising for real applications such as acoustic wave and vibration detection, and energy harvesting with very high power output (0.51 Watt) in comparison with the literature. iv) We used a 3D printing technique to produce our device, which is low-cost and appropriate for rapid prototyping and mass production. v) We explained the device theory for the triboelectric nanogenerator, which aligned well with our experimental results.
Open Access
Online lubricant degradation monitoring using contact charging of polymers
(Elsevier, 2022-05-15) Baytekin, Bilge; Baytekin, H. T.; Karluk, Azimet Akber; Ekim, Sunay Dilara
Lubrication of machine parts is necessary to prevent friction and wear in machine operation. However, oxidation of lubricants upon operation changes their chemical and physical properties and causes lubrication performance to deteriorate. Besides, one liter of wasted/used lubricant oil can contaminate a million liters of water. Current methods for the timely detection of oil deterioration lack practicality. Here we show simple, a triboelectrification-based method for oil degradation monitoring, in which the oxidation can be monitored by the changes in the contact charging (and separation) signals of oil-dipped cellulose and a common polymer tapped to each other. The commercial and base oil samples are oxidized at 100–200 °C for up to 80 h, simultaneously monitored by ATR-FTIR and the triboelectric method. The results show that a 40–90% decrease in the triboelectric open-circuit potentials in the presence of oxidized oil can directly indicate the start of oil oxidation without other accompanying analyses.
Open Access
Triboelectric nanogenerators : biomechanical energy harvesting, self powered sensor and wearable applications
(2017-09) Yavuz, Ahmet Faruk
One of the biggest challenges ahead massive advancement of electronic tech-nology is increasing energy consumption. A closer consideration on draining of fossil reserves and rapid development of wearable and portable consumer elec-tronics, inevitable paradigm shift is required towards use of renewable energy sources and self-powered electronic systems respectively. In parallel to this con-sideration, triboelectric nanogenerators have emerged to scavenge energy from ambient environment by using ubiquitous phenomenon of triboelectricity or con-tact electrification in other words. Essentially, triboelectric nanogenerators har-vest mechanical energy into electricity by utilizing triboelectric charge generation and electrostatic induction phenomenon. Accordingly, we developed high perfor-mance biomechanical energy harvesting floor tiles to scavenge human motions into electricity and electrode core-polymer shell structured triboelectric nanogen-erator fibers for wearable applications. Furthermore, new perspectives are intro-duced for fabrications of low-cost, mass producible, large area and flexible tribo-electric nanogenerator structures.