Polyethylene Terephthalate Layers Research Articles

Electret Properties of PET /AlOx Films with Protective Coating Based on Acrylic Copolymers

This paper describes the study of corona electrets made of a polyethylene terephthalate (PET) laminate film with an aluminum oxide nanolayer with a protective coating based on acrylic copolymers. Those films showed rather high and stable electret properties. At this, dipole polarization prevailed at the acrylic layer due to the orientation of oxygen-containing groups of atoms and macromolecular segments under the corona discharge, while injected charge carriers were located predominantly in polyethylene terephthalate layer at interfaces of both PET-aluminum oxide and amorphous-crystalline regions of the polymer.

Using woven recycled plastic fibers in reinforced concrete beams

The modern lifestyle, along with the advancement of new technologies has produced plastic waste and the recycling of these waste materials has become an important challenge for human societies. Polyethylene terephthalate (PET) is one of the most consuming waste materials. A solution to repel these materials is to use them in the civil engineering industry and buried them in concrete. PET layers and strips were used in reinforced concrete beams instead of steel reinforcements by some researchers. But, in this study, the longitudinal and transverse steel bars were replaced by woven recycled plastic fibers and tested experimentally. These woven PET bars are produced by the authors and used as a structural element. Six beams with different combinations of steel and woven PET bars are tested under two-point loading and the experimental and analytical results are presented. The results show that using these fibers concludes to increases the ductility of reinforced concrete beams. By replacing PET ropes instead of one, two and three tensile steel reinforcements, the ductility ratios of the beams are about 1.73, 1.76 and 4.12 times of the reference reinforced concrete beam. Moreover, some theoretical formulation is presented and compared with experimental data.

IoT enabled vehicle recognition system using inkjet-printed windshield tag and 5G cloud network

An IoT-enabled vehicle recognition system is developed and tested in this work, besides the tag antenna design and prototype for the vehicle windshield. Firstly, a flexible, surface-tolerant, low-profile, and low-cost passive UHF-RFID windshield tag inlay is designed. The tag is prototyped as wet-inlay with silver conductive-ink inkjet printed antenna on Polyethylene-Terephthalate layer, bonded with Higgs-EC IC. The dimension of the antenna is 0.25 × 0.05λ0. The overall inlay structure is around 0.27 × 0.06λ0. The antenna is designed at ETSI band, with a return loss of −14 dB at 900 MHz and a read range of 13.3 m and 8 m over lower and upper bands, respectively. The antenna demonstrates an omnidirectional radiation pattern and a maximum gain of 1.92 dBi. The developed prototype is tested in both indoor and outdoor environments. Secondly, the data is sent over the IoT cloud where decision-making is made for authorization. The reader data is transmitted over MQTT broker, via the Scotland 5G network to the MongoDB database using Python module Pymongo. The algorithm for vehicle recognition is written and verified by testing the dummy registered tags for access authorization, with a 100% recognition accuracy. We achieved higher read ranges, surface tolerance, and low profile features, comparatively. The overall system shows optimally great results.

Alkaline hydrolysis of photovoltaic backsheet containing PET and PVDF for the recycling of PVDF

Recovering fluorine from end-of-life products is crucial for the sustainable production and consumption of fluorine-containing compounds because fluorspar, an important natural resource for fluorine, is currently at a supply risk. In this study, we investigated the feasibility of chemically recycling a fluorine-containing photovoltaic (PV) backsheet for fluoropolymer recycling. Herein, a PV backsheet consisting of laminated polyethylene terephthalate (PET) and polyvinylidene fluoride (PVDF) was treated with different concentrations of sodium hydroxide (NaOH) to hydrolyze the PET layer to water-soluble sodium terephthalate (Na2TP) and to separate pure PVDF layer as a solid material. Optimized alkaline conditions (up to 10 M NaOH at 100 °C for 2 h) were determined, under which 87% of the PET layer could be decomposed without any significant deterioration of the PVDF layer. The hydrolysis kinetics of PET layer in NaOH could be explained by the modified shrinking-core model. Considering that the mass of end-of-life PV panels in Japan is estimated to increase to approximately 280,000 tons per year by 2036, PV backsheets are attractive candidates for fluoropolymer recycling, which can be effectively achieved using chemical recycling approach demonstrated in this study.

Development of a reusable low-cost facemask with a recycled hydrophobic layer for preventive health care.

The current work focuses on designing a low-cost, reusable, and highly efficient facemask for protection from respiratory droplets that cause COVID-19, other infection-causing organisms, and dust allergies. Several masks available in the market are single-use that would choke the environment through plastic pollution or are expensive for the commoner to afford. In the present study, the facemask incorporates a waste-derived polyethylene terephthalate (PET) layer and a non-woven polypropylene (PP) layer sandwiched between two tightly woven cotton layers. Combining these layers provides comfort and breathability, besides high bacterial and particulate filtration efficiency. Moreover, the unique PET layer provides mechanical strength and a 3D shape that enables hindrance-free speaking and prevents spectacle fogging. Compared to commercial N95 masks, the developed mask can be reused up to 30 washes and recycled with zero waste discharge ensuing green technology. Moreover, the mask was produced at an affordable cost of Rs. 17 (0.22 USD), including labor charges, and sold at a 100% profit margin @ Rs.35 (0.45 USD) per unit. Further, the mask was certified by neutral testing agencies and provided to a population of more than 6 lakhs, thus significantly contributing to the mitigation of COVID-19.

Development, testing, and evaluation of the daylighting, thermal, and energy-saving performance of semitransparent radiative cooling glass in cooling-dominated regions

Glass-made building envelopes play an essential role in buildings’ thermal/daylighting environment and energy behavior. To enhance its overall energy efficiency in cooling-dominated regions, a double-layer film that combines the concepts of selective solar utilization (SSU) and radiative cooling (RC) is proposed to form the semitransparent energy-saving glass (SESG). The SSU film (∼0.1 mm) is a multilayer optical film that contains polyethylene terephthalate (PET) and thin reflective metal layer. The RC film (∼0.1 mm) consists of a PET layer and an adhesion layer. To evaluate the daylighting, thermal, and energy-saving performance of the SESG on buildings, comparative field tests using reduced-size model boxes and whole-building energy simulation analysis on a larger-scale office building are conducted. Compared with the normal clear glass, the developed SESG decreases the indoor air temperature of the modeled box by maximum values of 19.1℃ and 17.8℃ while reducing the daylighting level by 68 % to support a more comfortable thermal/daylighting environment. In addition, a single-story office building modeling using EnergyPlus was developed to evaluate the energy-saving and daylighting performance of the SESG in two different cooling-dominated cities, Male (Maldives) and Hong Kong (China) considering different glazing ratios. Compared with normal clear glass which will add amounts of extra cooling load and cause serious glare problems due to its high transmittance to visible light and near-infrared solar radiation, the annual cooling energy savings of the SESG reach 15 %—60 % in two selected cities under different glazing ratios. By considering both energy-saving potential and daylighting quality, the simulation results show that in Male, within the glazing ratios of 0.4 to 0.6, the UDI (Useful Daylighting Illuminance) values and energy-saving potential both reach the highest value of 0.5–0.6 and ∼ 55 %. In Hong Kong, the UDI values and energy-saving potential both reach the highest value of 0.4–0.5 and ∼ 57 % when the glazing ratio ranges between 0.5 and 0.9. The experimental and simulation results validate that combining selective solar utilization and radiative cooling for the glass envelopes is able to seek a more efficient balance between the energy behaviors and daylighting environment for buildings in cooling-dominated regions.

Design of an Optically Transparent Microwave Absorber Based on Coding Metasurface

In this paper, a metamaterial absorber with a checkerboard patterned ITO (indium tin oxide) film as the surface is obtained by using flexible and optically transparent wave-absorbing material ITO–PET (polyethylene terephthalate), and a coding arrangement of two basic coding units based on the APS-PSO (Array Pattern Synthesis -Particle Swarm Optimization) algorithm. The surface structure of the absorber consists of ITO rectangular patch structures and ITO circular patch structures (110 Ω/sq). The ITO rectangular patch structures and ITO circular patch structures are symmetrical. The middle layer is made up of two layers of PET and one layer of PMMA, and the bottom surface is covered with a layer of low square resistance ITO film (8 Ω/sq). The experimental results, which are consistent with the simulation results, show that the absorber has superior performance: over 90% absorptance in the 5.06–9.01 GHz band, high transmittance, and a −10 dBsm RCS (radar cross-section) reduction in the 5.3–8.7 GHz band. This design also has polarization insensitivity and angular stability.

Ultra‐wideband metamaterial absorber based on frequency selective resistive film for 5G spectrum

AbstractAn ultra‐wideband metamaterial absorber (MA) is proposed for 5G communication, which features a resistive frequency selective surface printed on a PET (polyethylene terephthalate) layer and a ground layer of resistive film. The proposed MA can provide over 90% absorptivity in the frequency range of 11.2–42.8 GHz. Moreover, it is insensitive to polarization and wide incident angles. The effective medium theory and multi‐reflection interference theory are used to interpret the broadband absorption mechanism. The surface current distribution at three absorption peaks is investigated to further study the physical mechanism behind the wideband absorption. The measured results of the fabricated prototype are in good agreement with the simulation ones, thus verifying the robustness of the design. The presented MA can probably be used in electromagnetic shielding of 5G signals.

Design and analysis of an optically transparent ultra-wideband absorber covering C-, X-, ku-, k-, ka- bands

In this paper, an optically transparent ultra-wideband electromagnetic absorber (EMA) is designed using indium tin oxide (ITO) film. To achieve a transparent property, the traditional dielectric substrate and copper are replaced by polyethylene terephthalate (PET) and ITO film. The ultra-wideband absorbing is achieved through the combination of multilayer periodic ITO structures etched on flexible PET layers. The simulation results show that the design can absorb EM waves in the frequency range of 3.72-42.42 GHz (relative bandwidth 165.75%), while its overall thickness is only 0.669λ0 (λ0 is the wavelength at the center frequency of EMA). The design also has the property of polarization insensitive and angular stability. Finally, the absorber is fabricated and measured to prove the effectiveness.

Transparent Triboelectric Nanogenerator Based on Thermoplastic Polyurethane Films.

This study aims at investigating flexible and transparent thermoplastic polyurethane (TPU) as a novel material for triboelectric nanogenerator (TENG) devices with a polyethylene terephthalate layer. Devices having TPU-either as a flat film or as electrospun micrometer-dimension fibers with varying concentrations of TPU-were tested. The best output performing device provided 21.4 V and 23 μA as open-circuit voltage and short-circuit current respectively, with the application of a small force of 0.33 N indicating the high efficiency of the device. Devices with flat films-obtained using the doctor-blade (DB) technique-have high transparency (80%) as well as high TENG output. The topography of the TPU layer, characterized by atomic force microscopy, reveals nanoscale roughness of the film surface. Finally, we demonstrate that gentle hand tapping on the TENG device can power upto 11 light-emitting diodes (LEDs). The high transparency, lightweight, simple fabrication, flexibility, and robust features of such device make it an added value for various optoelectronic applications.

Результаты каротидного стентирования при асимптомных стенозах сонных артерий

Objective: prospective analysis of 30-day outcomes from stenting procedure in patients with asymptomatic internal carotid artery stenosis depending on the type of implanted stent. Material and Methods: the study included 108 patients who underwent endovascular surgical treatment for asymptomatic internal carotid artery stenosis from 2012 to 2017. Depending on the type of implanted stent the patients were divided into 4 groups (the first (n = 37) – steel, the second (n = 32) -nitilon, the third (n = 20) – doublelayered stents, the fourth (n = 19) – double-layer stents with an inner layer of polyethylene terephthalate. Results: there was no mortality in the studied groups for 30 days after surgery. The cumulative incidence of cerebral circulation disorders within 30 days of carotid angioplasty and stenting was 9.7% (n = 10), with ischemic stroke occurring in 1.85% (n = 2) cases. Conclusion: carotid angioplasty and stenting is a safe and effective method of secondary prevention of cerebral circulation disorders with the level of perioperative complications not exceeding other preventive procedures.

A Flexible and Stretchable Bending Sensor Based on Hydrazine-Reduced Porous Graphene for Human Motion Monitoring

In this work, we developed a flexible and stretchable bending sensor that is made of graphene film decorated with dense pores and sealed with both polyethylene terephthalate (PET) and elastic rubber layers. The graphene film was laid on a PET substrate to disperse the stretching stress and then covered by another smooth PET layer for reducing shear force. Platinum-catalyzed silicone rubber was employed for protecting the graphene film and providing the stretchability of the whole structure. Properties of the graphene film were investigated through the scanning electron microscope (SEM), Raman spectrometer, X-ray diffraction, and mechanical evaluations. Results indicate that the sensitivity of the proposed bending sensor reaches 1.092 mV/deg with excellent linearity and the resolution achieves 1°. Satisfactory repeatability was also observed with a mean square error of 0.105 of ignorable distortion after 1000 cycles of bending. On-human experiments verified that the bending sensor could accurately sense the bending angles of different human joints without additional structural modification. The results lead us to believe that the proposed method is a promising path for fabricating flexible and stretchable sensors with high performance and stability.

Dimensional stability and deformation analysis under mechanical loading of recycled PET-wood laminated composites with digital image correlation

The aim of this study is to investigate the dimensional stability, bending strength and modulus of elasticity at bending of recycled polyethylene terephthalate (PET) layers - wood laminated composites bonded with polyurethane (PU) adhesive and to analyze the deformation behavior with digital image correlation (DIC) during the bending test. The waste beverage bottles were collected from a trash bin and granulated with a cutter. PET layers were obtained by molding the granules at 265 °C under a hydraulic pressure. The composites were prepared with three and five layers of wood veneers and PET layers by using a hydraulic press at room temperature (24 °C) for 4 h. The digital image correlation was conducted to detect the deformation behavior of the composites during the bending test. According to the obtained results, water absorption and thickness swelling decreased with the addition of PET layers. Especially, PET layers outside blocked water absorption of the composites and provided higher resistance to water absorption in the composites when the amount of PET layers was raised. The presence of the PET layers decreased the bending strength and modulus of elasticity at bending of the composites, and the decrease in the bending strength and modulus of elasticity at bending was determined to range from 15% to 30%–46% and 50%, respectively. The mechanical simulation results obtained with the DIC were found to be similar to the results determined with the experimental test. The DIC results processed with open-source 2D digital image correlation MatLab software (NCORR) indicated higher deformation area and more densified stress distribution on the surface of the composites with PET layers.

Analysis of weld geometry and liquid flow in laser transmission welding between polyethylene terephthalate (PET) and Ti6Al4V based on numerical simulation

The laser transmission welding of polyethylene terephthalate (PET) and titanium alloy Ti6Al4V involving the evaluating of the resultant geometry and quality of welds is investigated using a fiber laser in this paper. A 3D transient numerical model considering the melting and fluid flow is developed to predict the weld geometry and porosity formation. The temperature field, molten pool and liquid flow are simulated with varying laser power and welding speed based on the model. It is observed that the weld geometry predictions from the numerical simulation are in good agreement with the experimental data. The results show that the porosity consistently appears in the high temperature region due to the decomposition of PET. In addition, it has also been found that the molten pool with a vortex flow pattern is formed only in the PET layer and the welding processing parameters have significant effects on the fluid flow, which eventually affects the heat transfer, molten pool geometry and weld formation. Consequently, it is shown adopting appropriate welding processing parameters based on the proposed model is essential for the sound weld without defects.

Synthesis of a novel microcapsule flame retardant and flame-retardant property of its composites with poly (ethylene terephthalate)

A novel halogen-free microcapsule flame retardant, carbon microspheres coated with magnesium hydroxide microcapsule and polyethylene terephthalate (PET) (MMH@CMSs) were synthesized. Then, the prepared MMH@CMSs were introduced into PET resin to prepare MH@CMSs/PET composites. The morphology and structure of MMH@CMSs were characterized by SEM, TEM and FTIR, which showed that an organic shell layer of PET as capsule wall was coated on the surface of MH@CMSs. The prepared MMH@CMSs/PET reached the LOI of 27.4 with only 1wt.% MMH@CMSs, and UL94 test results showed that MMH@CMSs/PET reached UL94 V-0 rating when the dosage of MMH@CMSs was over 1.5wt.%. Tensile properties results showed that the microcapsule treatment of MH@CMSs significantly improved the mechanical properties of the composite, and the tensile strength of 1wt.% MMH@CMSs/PET increased by 83.9% compared with 1wt.% MH@CMSs/PET. The flame retardant mechanism was studied by cone calorimeter measurement, TGA, TGA-FTIR, SEM and FTIR. The results disclosed that MMH@CMSs enhanced the thermal stability of PET in air, and promoted PET to form a dense and continuous protective char layer that effectively blocked heat transfer and combustible gas release.

고연성 PET 섬유로 보강된 철근콘크리트 보의 부착 및 휨 거동

이 연구에서는 고연성과 낮은 탄성계수를 갖는 PET 섬유로 보강한 철근콘크리트 보의 부착특성과 휨거동을 각각 부착실험 및 휨실험을 통하여 규명하고자 하였다. 부착실험은 CSA S806에 따라 수행하였고, 실험변수는 섬유 종류와 보강량(CF 및 GF 시트 각 1겹, PET 시트 10겹)이었다. 총 8개의 보 실험에서 주요 실험변수는 단면의 연성비(<TEX>${\mu}=3.4$</TEX>, 7.0), 보강섬유 종류(CF, GF, PET) 및 보강량이었다. 보 단면의 모멘트-곡율 해석을 병행하였다. 부착실험의 결과, CF, GF 시트 1겹 보강에서 유효 부착길이는 각각 120, 60 mm 이었고 최대부착응력은 각각 3.25, 2.99 MPa 이었다. PET 10겹 보강에서 유효 부착길이는 60 mm, 최대 및 평균 부착응력은 각각 2.30, 2.10 MPa 이었다. 또한 최대 강도 시 CF, GF, PET의 변형율은 각각 0.36%, 0.49%, 6.29% 였으며 CF, GF 부착실험체는 계면에서 시트가 최종적으로 탈락하였지만 PET 부착 실험체에서 박리현상은 나타나지 않았다. 휨실험의 결과, PET 10, 20, 30겹으로 보강한 RC 보의 휨강도, 휨강성이 모두 무보강 보에 비해 증가하였고, 연성적인 휨파괴 양상을 보였으나 PET 30겹의 경우 20겹에 비하여 연성이 감소하였다. 모멘트-곡율 해석의 결과, PET 보강 보에서 접착제의 물성을 해석에 포함시키면 해석의 정확도가 향상하였다. 한편 PET 의 내구성에 대해서는 보고된 문헌이 없어서 현재 연구 진행 중이다. An experimental study was performed to investigate flexural performance and bond characteristics of RC beams strengthened using ductile polyethylene terephthalate(PET) with low elastic modulus. Bond tests were planned and completed following CSA S806. Test variables were fiber type and fiber amount. Also, total of 8 RC beams was tested. Major test variables of the beam tests included section ductility(<TEX>${\mu}=3.4$</TEX>, 7.0), fiber type(CF, GF, PET) and amount of fiber strengthening. Moment-curvature analyses of the beam sections were also performed. In bond tests, the bond stress distribution as well as the maximum bond stress increased with increasing amount of PET. In case of 10 layers of PET, the effective bond length was 60 mm with the maximum and the average bond stress of 2.33 and 2.10 MPa, respectively. RC beam test results revealed that the moment capacity of the RC beams strengthened using PET 10 and 20 layers increased over the control beam with little reduction in ductility by fiber strengthening. All beams strengthened using PET resulted in ductile flexural failure without any sign of fiber debonding or fiber rupture. It was important to include the mechanical properties of adhesive in the moment-curvature analysis of PET-strengthened beam sections.

(Invited) Improved the Impedance Spectroscopy Measurements with Non-Contact Microelectrodes Embedded into a Flexible Polymer Comprising a Microfluidic Network

In the last decade, the flexible microdevices were abundtly developed for microfluidics. Among the electric measurement strategies for sensors or biosensors, the electric impedance spectroscopy on insulated polymer sandwiched between two microelectrodes is promising as new technique for detection strategy because of the absence of direct contact between the microelectrodes and solution flowing in the fluidic microchannel. Our strategy is based on the capacitive coupling between the microelectrodes galvanically isolated in a dielectric polymer such as polyethylene terephthalate (PET) into which a fluidics microchannel is designed by laser photoablation procedure [1],[2]. In other words, the capacitive coupling takes place between the two planar microband electrodes located on one side of the dielectric polymer and the fluidics microchannel solution in contact with the other side. In brief, the thin dielectric polymer layer (e=5 µm) is sandwiched between the two microelectrodes (electronic charges) and a flow microchannel (ionic charges). More recently a detailed methodology for non-contact impedance in such dielectric microdevice has been published [3,4] that presents a procedure to eliminate the impedance contribution of the PET layer which separates the two embedded microelectrodes. This procedure enables a clear observation of the impedance of the solution in the microchannel associated in series with the interfacial impedance (PET surface / Solution). Indeed, eliminating the contribution of the impedance of the polymer enables new applications such as conductometry in the high-frequencies [4]. Conversely, this configuration permits in the low-frequencies the monitoring the interfacial impedance change onto polymer. Indeed, the PET surface charge state depends on the chemical surface modification of the PET. Some applications and results of the use of the non-contact impedance spectroscopy over a fluidics microchannel will be presented. For instance, the adsorption monitoring of proteins on the polymer surface or the contactless conductivity variation while a chemical reaction takes place in the fluidic channel. Modelling of the interface constituted by PET/microelectrode/electrolyte were investigated using the electrical equivalent circuits approach or using numerical calculations permittingto extract the value of the interfacial impedance for an ultralow protein concentration. The promising results obtained with a detected labelling-free protein represent a competing method with optical instruments using surface plasmon resonance (SPR).

Sci‐Sat AM: Radiation Dosimetry and Practical Therapy Solutions ‐ 01: Optimization of an organic field effect transistor for radiation dosimetry measurements

Purpose:To use Monte Carlo simulations to optimize the design of an organic field effect transistor (OFET) to maximize water‐equivalence across the diagnostic and therapeutic photon energy ranges.Methods:DOSXYZnrc was used to simulate transport of mono‐energetic photon beams through OFETs. Dose was scored in the dielectric region of devices and used for evaluating the response of the device relative to water. Two designs were considered: 1. a bottom‐gate device on a substrate of polyethylene terephthalate (PET) with an aluminum gate, a dielectric layer of either PMMA or CYTOP (a fluorocarbon) and an organic semiconductor (pentacene). 2. a symmetric bilayer design was employed in which two polymer layers (PET and CYTOP) were deposited both below the gate and above the semiconductor to improve water‐equivalence and reduce directional dependence. The relative thickness of the layers was optimized to maximize water‐equivalence.Results:Without the bilayer, water‐equivalence was diminished relative to OFETs with the symmetric bilayer at low photon energies (below 80 keV). The bilayer's composition was designed to have one layer with an effective atomic number larger than that of water and the other with an effective atomic number lower than that of water. For the particular materials used in this study, a PET layer 0.1mm thick coupled with a CYTOP layer of 900 nm provided a device with a water‐equivalence within 3% between 20 keV and 5 MeV.Conclusions:organic electronic devices hold tremendous potential as water‐equivalent dosimeters that could be used in a wide range of applications without recalibration.

Thermal conductivity of plasma modified polyethylene terephthalate and polyamide-6 layers

Tribological performance of the materials greatly depends on the temperature of the contacting zones and sur- faces and hence on the heat conducting behaviour of the materials. Heat conduction of polymers is, however, greatly affected even by a very narrow (few tens of nm) modified layer formed on the surface after subjecting the polymer to plasma treatment. In this article the heat flow inhibiting properties of plasma modified surface layers were investigated on polyethylene terephthalate (PET) and polyamide-6 (PA6) engineering polymers. Nitrogen Plasma Immersion Ion Implanta- tion gave rise to compositional and structural changes of the polymers in a depth of 110 nm. It was found that even this thin layer exhibited significant heat flow inhibiting effect. The modified layer considerably decreased the thermal conductivity coefficient of the treated polymer and resulted in a reduced heat transmission for PET and PA6 by 33 and 28%, respectively. This new information supports and is in accordance with the former tribological results about extra friction heat generation experienced under NPIII surface layer of PA6 and PET during dry sliding.

Comparative Experimental Study of Triboelectric Charging of Two Size Classes of Granular Plastics

The free fall triboelectrostatic separation is widely used for the selective sorting of plastics from granular industrial waste. The electric charge per mass ratio of the granules is a critical parameter influencing the purity of recycled plastics and the efficiency of the electrostatic separation process. The aim of the present study is to validate an experimental procedure for the optimization of the vibratory-type tribocharging device for granular plastics. This tribocharger is composed of a metal plate covered with a thin PET (polyethylene terephthalate) layer. The amplitude of the vibratory motion of the plate can be adjusted using a potentiometer. The length of the vibratory feeder, the flow rate, and the velocity, at which the granules move on its surface, are the variables that can be controlled in order to optimize the tribocharging process. As particle size is an important physical factor influencing the charging process, the study was focused on two size classes (1 to 2 mm and 2 to 5 mm) of ABS (acrylonitrile butadiene styrene) granules originating from the recycling process of waste electrical and electronic equipment. The optimum operating conditions, obtained by using the response surface modeling methodology, differ between the two size classes of granules. Both the length of the vibratory tray and the velocity of the granules on its surface have a significant effect on the outcome of the tribocharging process.