Polyethylene Terephthalate Polymer Research Articles

Wearable Sensor for Forearm Motion Detection Using a Carbon-Based Conductive Layer-Polymer Composite Film.

In this study, we developed a fabrication method for a bracelet-type wearable sensor to detect four motions of the forearm by using a carbon-based conductive layer-polymer composite film. The integral material used for the composite film is a polyethylene terephthalate polymer film with a conductive layer composed of a carbon paste. It is capable of detecting the resistance variations corresponding to the flexion changes of the surface of the body due to muscle contraction and relaxation. To effectively detect the surface resistance variations of the film, a small sensor module composed of mechanical parts mounted on the film was designed and fabricated. A subject wore the bracelet sensor, consisting of three such sensor modules, on their forearm. The surface resistance of the film varied corresponding to the flexion change of the contact area between the forearm and the sensor modules. The surface resistance variations of the film were converted to voltage signals and used for motion detection. The results demonstrate that the thin bracelet-type wearable sensor, which is comfortable to wear and easily applicable, successfully detected each motion with high accuracy.

Spatio-vertical distribution of riverine microplastics: Impact of the textile industry

Microplastics (MPs) contamination in rivers and lakes is of paramount environmental importance as freshwater systems transport MPs from land to ocean. However, information regarding the spatio-vertical distributions of MPs in rivers, and their associations with surrounding industrial activities, is scarce and unclear. This study investigated MPs in the Taipu River, where there is a highly developed textile industry in Yangtze River Delta, China. Results showed a widespread occurrence of MPs particles with concentrations in the range of 0.65–6.07 items/L and 0.30–3.63 items/L in surface and bottom waters. A higher abundance of MPs was observed in surface waters than in bottom waters (t = 5.423, p = 0.024). The MPs distributions varied markedly in space, with the highest abundances being found in textile manufacturing zones as a consequence of industrial release (F = 14.642, p < 0.001). Transparent fibers were the major MPs compositions with 100–500 μm in size. Polyethylene terephthalate (PET) accounted for 71.4% and 59.73% of the total MPs identified in surface and bottom water, respectively. These PET polymers were predominantly presented in “fibrous” shapes, further reflecting the point sources of textile wastewater. Moreover, polyvinyl acetate (PVAC), used as fabric coating and resin matrix to form nonwoven fabrics, was firstly highlighted at a watershed scale. Although risk assessments revealed a light to moderate risks of MPs in the Taipu River, textile wastewater appears to cause a high “grey water” footprint and increase the risks of MPs pollution from textile life-cycle production. This study bridged gaps between field data and policy-making for MPs control and shed insight into the cleaner production of the textile industry.

Plastics degradation by hydrolytic enzymes: The plastics-active enzymes database-PAZy.

Petroleum-based plastics are durable and accumulate in all ecological niches. Knowledge on enzymatic degradation is sparse. Today, less than 50 verified plastics-active enzymes are known. First examples of enzymes acting on the polymers polyethylene terephthalate (PET) and polyurethane (PUR) have been reported together with a detailed biochemical and structural description. Furthermore, very few polyamide (PA) oligomer active enzymes are known. In this article, the current known enzymes acting on the synthetic polymers PET and PUR are briefly summarized, their published activity data were collected and integrated into a comprehensive open access database. The Plastics-Active Enzymes Database (PAZy) represents an inventory of known and experimentally verified enzymes that act on synthetic fossil fuel-based polymers. Almost 3000 homologs of PET-active enzymes were identified by profile hidden Markov models. Over 2000 homologs of PUR-active enzymes were identified by BLAST. Based on multiple sequence alignments, conservation analysis identified the most conserved amino acids, and sequence motifs for PET- and PUR-active enzymes were derived.

Modification of Optical Bandgap and Formation of Carbonaceous Clusters Due to 1.75 MeV N5+ Ion Irradiation in PET Polymers and Search for Chemical Reaction Mechanisms

The effects of 1.75 MeV N5+ ion beams of varying fluences, ranging from 1x1011 to 5x1014 ions/cm2 on structural, optical, and chemical properties of polyethylene terephthalate (PET) polymer, have been investigated by x-ray diffraction (XRD), UV–Visible spectroscopy, and Fourier transform infrared (FTIR) spectroscopy. The XRD patterns of PET samples show that the crystallinity increases with ion irradiation of fluences 4x1011 and 5x1012 ions/cm2. Optical bandgap energy decreases more at the ion fluences of 5x1014 ions/cm2. Absorption maxima shifted towards a higher wavelength value due to the formation of extended conjugation. Acetylenic (-C≡C-) group formation and free CO2 group are confirmed by FTIR spectroscopy. The reaction mechanism of the degradation product formation chemistry is discussed.

Sodium hypochlorite as an oxidizing agent for removal of soil organic matter before microplastics analyses.

The omnipresence of microplastics (MPs) across Earth's surface has raised concerns about their environmental impact and created an urgent need for methods to identify them in complex soil and sedimentary matrices. However, detecting MPs in the O horizons of soils is difficult because plastic polymers share many physical and chemical properties with natural soil organic matter (SOM). In this study, we assessed whether sodium hypochlorite (NaOCl), a reagent that can oxidize SOM and simultaneously preserve mineral constituents, can be used for MP analysis and characterization in soil environments. In addition, we scrutinized how factors such as MP size, polymer type, extraction methods, and soil matrix affect the recovery of microplastic particles. We used both hydrophobic and density-dependent separation methods to assess the effects of our oxidation treatment on the recovery of MP. We observed that NaOCl effectively removed SOM without greatly altering the surface properties of resistant MP polymers (polypropylene, polylactic acid, low-density polyethylene, and polyethylene terephthalate), which were characterized using scanning electron microscopy and Fourier-transform infrared spectroscopy after SOM removal. The NaOCl treatment caused some chlorination and formation of additional C-OH bonds on polymer surfaces, which likely contributed to the reduced efficiency of the hydrophobic-based (oil) extraction. We conclude that NaOCl treatment can improve detection of MPs in SOM-rich soil and that recovery of MPs from soils is influenced by MP size, polymer type, extraction method, and soil type, which makes it challenging to develop a universal analytical method.

Polyethylene terephthalate clamps: Optimization in endodontic and restorative practices.

BackgroundThere is a growing search for innovations in dental materials and instruments and, therefore, an increase need to optimize the instruments used in the absolute isolation. The gold standard procedure contributes significantly to the quality of restorative and endodontic procedures. Thus, the aim of the present study was to evaluate the radiopacity of polyethylene terephthalate polymer clamps and compare them to conventional metal clamps. Material and MethodsThe polyethylene terephthalate clamp was developed at the University of Uberaba (Patent application #PI0901719-4, Uberaba, MG, Brazil). Five polyethylene terephthalate clamps and five conventional metal clamps were used. The clamps were positioned, next to an aluminum scale, under the same phosphor plate to perform 3 radiographs. The locator cylinder was set perpendicular to the radiographic films at a focal length of 20 cm and set to 60 kVp and 0.06 seconds. After image processing, optical density values were read using DBWin 5.0.4 software. The mean of the 3 readings taken on each clamp was adopted as the radiodensity of the specimen. The differences between the groups were compared using Student’s t-test (p<0.05). ResultsPolyethylene terephthalate clamps demonstrated significantly lower radiopacity than conventional metal clamps (p<0.05). ConclusionsPolyethylene terephthalate clamps have lower radiopacity when compared to conventional metal clamps. Key words:Rubber Dams, Dentistry, Operative, Endodontics.

Generation of Atmospheric Pressure Dielectric Barrier Discharge (DBD) Using Water Electrode

In this experiment, an atmospheric pressure dielectric barrier discharge (DBD) generated with a water electrode is investigated by means of optical measurements and imaging. The discharge was generated using a high voltage (0-20kV) power supply operating at 10-30 kHz with water as one of the electrode and borosilicate glass as a dielectric barrier of 2.5mm thickness. This paper reports the generation and characterization of atmospheric pressure plasma in nitrogen environment and its application in the surface modification of polyethylene terephthalate (PET). The generated plasma has been characterized by image analysis and optical emission spectroscopy. Our results showed that the distribution of micro-discharges depends significantly on the inter electrode gap and applied voltage. In order to characterize the discharge, electron temperature has been determined by using line intensity ratio method. The results showed that Te depends on applied voltage and pressure inside the chamber. The values of Te were found to be 1.40 eV and 0.95 eV applied at 1kV and 10kV voltage using 1% concentration. The discharge was produced at various conditions for the study of effectiveness of treatment on the surface property of Polyethylene terephthalate (PET). After the treatment of the sample in different treatment time: 10s, 20s, 40s, and 60s, the hydrophobic properties of sample changed to the hydrophilic. To investigate the effect of plasma treatment on Polyethylene terephthalate (PET) polymer contact angle was measured by using goniometer with water as a testing liquid. The surface properties of the untreated and plasma treated PET samples were characterized by contact angle measurement, and surface energy analysis. Before treatment the contact angle for untreated sample was 77.1° and after treatment its contact angle becomes 38.7° , 35.04° , 33.6° and 31.6° respectively.

An artificial neural network prediction on physical, mechanical, and thermal characteristics of giant reed fiber reinforced polyethylene terephthalate composite

Plant fiber reinforced hybrid polymer composites have had broad applications recently because of their lower cost advantages, lower weight, and biodegradable nature. The present work studies the influence of reinforcing giant reed fiber concentration in polyethylene terephthalate (PET) polymer for their physical, mechanical, and thermal characteristics and determines the optimum loading of giant reed fiber using an artificial neural network (ANN) scheme. Giant reed fiber reinforced PET matrix laminates were manufactured from compression molding with different fiber loadings such as 5 wt.%, 10 wt.%, and 20 wt.%. The mechanical characteristics such as tensile and flexural strength and the laminate’s tensile and flexural modulus were appraised and examined. The maximum value of tensile strength, flexural strength, tensile modulus, and flexural modulus were 5.4 MPa, 26 MPa, 8343 MPa, and 6300 MPa, respectively, for PET2 (10 wt.% of giant reed fiber in PET polymer) composite. Fiber pullout, gaps, and fracture behavior were examined from a scanning electron microscope in the microstructural analysis. A machine learning technique has been recommended to combine artificial intelligence while designing giant reed fiber reinforced polymeric laminates. Using the suggested method, an ANN model has been generated to attain the targeted giant reed fiber concentration for PET composite while gratifying the necessary targeted characteristics. The developed method is very effective and decreases the effort and time of material characterization for huge specimens. It will support the researchers in designing their forthcoming test efficiently.

Current Advances in the Biodegradation and Bioconversion of Polyethylene Terephthalate.

Polyethylene terephthalate (PET) is a widely used plastic that is polymerized by terephthalic acid (TPA) and ethylene glycol (EG). In recent years, PET biodegradation and bioconversion have become important in solving environmental plastic pollution. More and more PET hydrolases have been discovered and modified, which mainly act on and degrade the ester bond of PET. The monomers, TPA and EG, can be further utilized by microorganisms, entering the tricarboxylic acid cycle (TCA cycle) or being converted into high value chemicals, and finally realizing the biodegradation and bioconversion of PET. Based on synthetic biology and metabolic engineering strategies, this review summarizes the current advances in the modified PET hydrolases, engineered microbial chassis in degrading PET, bioconversion pathways of PET monomers, and artificial microbial consortia in PET biodegradation and bioconversion. Artificial microbial consortium provides novel ideas for the biodegradation and bioconversion of PET or other complex polymers. It is helpful to realize the one-step bioconversion of PET into high value chemicals.

The comparison of triboelectric power generated by electron-donating polymers KAPTON and PDMS in contact with PET polymer

Abstract The Triboelectric nanogenerators (TENGs) are Fabricated by contact between two surfaces of different materials and convert of electric loads between them. In such structures, the two contacting layers should be radically different in terms of their electric property so that one of the layers could induce positive electrical charge while the other induces a negative charge. The application of force on and friction between the two layers induce positive and negative charges. Through the electrodes in external load, the electrical charges flow as electric current. In the present study, TEGN structures fabricated of polyethylene terephthalate polymers (PET) act as electron acceptor while Polyamide (KAPTON) and polydimethylsiloxane (PDMS) act as electron donator. The resulting outputs are compared consequently. Considering the fact that the two materials are relatively identical in terms of electron donation as they are in contact with PET, the generators fabricated of KAPTON could generate 400% more power under identical conditions. Therefore, one may conclude that KAPTON could be more suitable for development of self-power system as they are more available and more environmentally compatible.

Adsorptive Recovery of Cu2+ from Aqueous Solution by Polyethylene Terephthalate Nanofibres Modified with 2-(Aminomethyl)Pyridine

The accumulation of plastic waste products in the environment has adversely affected wildlife and human beings. Common plastics that accumulate in the environment are plastics that are made of polyethylene terephthalate (PET) polymer. PET plastic waste products can be recycled for beneficial use, which would reduce their negative impacts. In this study, modified PET or waste PET (WPET) from plastic bottles was blended with powder commercial 2-(aminomethyl)pyridine (SiAMPy) resin and electrospun into composite nanofibres and applied for Cu2+ adsorption. PET-SiAMPy or WPET-SiAMPy composite nanofibres fibre diameters from the HRSEM images were 90–140 nm and 110–155 nm, respectively. In batch adsorption experiments, PET-SiAMPy or WPET-SiAMPy composite nanofibres achieved Cu2+ adsorption equilibrium within 60 secs of contact time with 0.98 mmol/g (89.87%) or 1.24 mmol/g (96.04%) Cu2+ adsorption capacity. The Cu2+ complex formation rate (k) with WPET-SiAMPy was 0.0888 with the mole ratio of Cu2+ and WPET-SiAMPy nanofibres 1:2. The complex molecular formula formed was Cu(WPET-SiAMPy)2 with a square planar geometry structure. The WPET-SiAMPy nanofibres’ adsorption was best fitted to the Freundlich isotherm. WPET-SiAMPy composite nanofibres were considered highly efficient for Cu2+ adsorption from aqueous solution and could be regenerated at least five times using 5 M H2SO4.

Accelerated Aging Effect on Mechanical Properties of Common 3D-Printing Polymers.

In outdoor environments, the action of the Sun through its ultraviolet radiation has a degrading effect on most materials, with polymers being among those affected. In the past few years, 3D printing has seen an increased usage in fabricating parts for functional applications, including parts destined for outdoor use. This paper analyzes the effect of accelerated aging through prolonged exposure to UV-B on the mechanical properties of parts 3D printed from the commonly used polymers polylactic acid (PLA) and polyethylene terephthalate–glycol (PETG). Samples 3D printed from these materials went through a dry 24 h UV-B exposure aging treatment and were then tested against a control group for changes in mechanical properties. Both the tensile and compressive strengths were determined, as well as changes in material creep characteristics. After irradiation, PLA and PETG parts saw significant decreases in both tensile strength (PLA: −5.3%; PETG: −36%) and compression strength (PLA: −6.3%; PETG: −38.3%). Part stiffness did not change significantly following the UV-B exposure and creep behavior was closely connected to the decrease in mechanical properties. A scanning electron microscopy (SEM) fractographic analysis was carried out to better understand the failure mechanism and material structural changes in tensile loaded, accelerated aged parts.

Conversion of Waste Polyethylene Terephthalate (PET) Polymer into Activated Carbon and Its Feasibility to Produce Green Fuel.

In this study, a novel idea was proposed to convert the polyethylene terephthalate (PET) waste drinking-water bottles into activated carbon (AC) to use for waste cooking oil (WCO) and palm fatty acid distillate (PFAD) feasibility to convert into esters. The acidic and basic char were prepared by using the waste PET bottles. The physiochemical properties were determined by employing various analytical techniques, such as field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR), Brunauer–Emmett–Teller (BET) and temperature-programmed desorption – ammonia/carbon dioxide (TPD-NH3/CO2). The prepared PET H3PO4 and PET KOH showed the higher surface area, thus illustrating that the surface of both materials has enough space for impregnation of foreign precursors. The TPD-NH3 and TPD-CO2 results depicted that PET H3PO4 is found to have higher acidity, i.e., 18.17 mmolg−1, due to the attachment of phosponyl groups to it during pretreatment, whereas, in the case of PET KOH, the basicity increases to 13.49 mmolg−1. The conversion results show that prepared materials can be used as a support for an acidic and basic catalyst for the conversion of WCO and PFAD into green fuel.

Non-targeted analysis for organic components of microplastic leachates

Organic components of microplastic leachates were investigated in an integrated non-targeted analysis study that included statistical analysis on leachates generated under different leaching scenarios. Leaching experiments were undertaken with simulated gastric fluid (SGF), river water, and seawater with common polymer types, including polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, and polyester fabrics comprising both raw and recycled materials. Totals of 111.0 ± 26.7, 98.5 ± 20.3, and 53.5 ± 4.7 different features were tentatively identified as compounds in SGF, freshwater, and seawater leachates, respectively, of which 5 compounds were confirmed by reference standards. The leaching capacities of the media were compared, and the clusters of structurally related features leached in the same medium were studied. For leachates generated from raw and recycled plastics, volcano plots and Pearson's Chi-squared tests were used to identify characteristic features. More characteristic features (3−20) had an average intensity across all recycled plastics that were significantly higher (p < 0.05) than that (1–3) of raw plastics under different conditions. The results indicate that gastric solution is more likely to leach components from microplastics, and there exists the difference of leachate's organic composition between raw and recycled materials, providing new insights into understanding microplastic environmental effects.

Polymer tiles from polyethylene terephthalate (PET) wastes and fly ash: mechanical properties and durability

Background: Plastic waste (PW) is becoming increasingly hazardous to the environment as a result of its massive production, causing significant damage to both the ecosystem and its inhabitants. Managing plastic waste is a global concern due to its non-biodegradable nature. However, it is important to handle PWs properly to curtail the environmental emissions associated with their incineration and dumping into landfills. This research investigates the possibility of producing tiles from polyethylene terephthalate (PET) waste bottles and fly ash. The mechanical properties, as well as the chemical resistance of the manufactured PET polymer tiles, are reported in this study. Methods: PET waste was used in varying proportions (from 30% to 100%) by sand weight. The shredded PET waste was heated at 230 oC before being suitably blended with fly ash. It was then poured into the designated mold, removed after one hour, and cooled for 24 hours before testing. Results: The assessment of the physical and mechanical properties of the materials revealed that the tiles produced with 30% PET content performed better in terms of material density and strength compared to the samples with higher PET content. The highest compressive strength being 6.88 MPa. Based on the results of the tests, the produced PET tiles have a low water absorption efficiency of 80% lower when compare to cement and ceramic tiles (the water absorption values are between 0.98% and 0.09%). Conclusions: The results from this study indicate that PET waste bottles can be used to produce long-lasting, durable, and extremely low water absorption eco-friendly tiles for both residential and commercial applications. This prospect of tile production using polyethylene terephthalate (PET) waste and fly ash would not only minimize the cost of building products but will also act as a waste diversion to mitigate environmental emissions caused by plastic waste disposal.

Temperature Field-Assisted Ultraviolet Nanosecond Pulse Laser Processing of Polyethylene Terephthalate (PET) Film.

Understanding the mechanism of and how to improve the laser processing of polymer films have been important issues since the advent of the procedure. Due to the important role of a photothermal mechanism in the laser ablation of polymer films, especially in transparent polymer films, it is both important and effective to adjust the evolution of heat and temperature in time and space during laser processing by simply adjusting the ambient environment so as to improve and understand the mechanism of this procedure. In this work, studies on the pyrolysis of PET film and on temperature field-assisted ultraviolet nanosecond (UV-ns) pulse laser processing of polyethylene terephthalate (PET) film were performed to investigate the photothermal ablation mechanism and the effects of temperature on laser processing. The results showed that the UV-ns laser processing of PET film was dominated by the photothermal process, in which PET polymer chains decomposed, melted, recomposed and reacted with the ambient gases. The ambient temperature changed the heat transfer and temperature distribution in the laser processing. Low ambient temperature reduced the thermal effect and an increase in ambient temperature improved its efficiency (kerf width: 39.63 μm at −25 °C; 48.30 μm at 0 °C; 45.81 μm at 25 °C; 100.70 μm at 100 °C) but exacerbated the thermal effect.

Adsorption of enzymes with hydrolytic activity on polyethylene terephthalate

Polyethylene terephthalate (PET) degrading enzymes have recently obtained an increasing interest as a means to decompose plastic waste. Here, we have studied the binding of three PET hydrolases on a suspended PET powder under conditions of both enzyme- and substrate excess. A Langmuir isotherm described the binding process reasonably and revealed a prominent affinity for the PET substrate, with dissociation constants consistently below 150 nM. The saturated substrate coverage approximately corresponded to a monolayer on the PET surface for all three enzymes. No distinct contributions from specific ligand binding in the active site could be identified, which points towards adsorption predominantly driven by non-specific interactions in contrast to enzymes naturally evolved for the breakdown of insoluble polymers. However, we observed a correlation between the progression of enzymatic hydrolysis and increased binding capacity, probably due to surface modifications of the PET polymer over time. Our results provide functional insight, suggesting that rational design should target the specific ligand interaction in the active site rather than the already high, general adsorption capacity of these enzymes.

A new protocol to assess the microplastics in sewage sludge

Pollution from plastics and their slow degradation are current problems that require urgent solutions. The natural degradation of plastics leads to its fragmentation, resulting not only in microplastics (MPs) but also in nanoplastics (NPs). In recent years, research and monitoring of MPs and NPs concentrations has increased. The monitoring of their concentrations in the environment, sampling sites, detection and quantification methods are not standardised due to the inherent properties of the materials and the origin of the samples, which tends to make the comparison of data between different studies difficult. In this study, we developed an H2O2-enzyme protocol for the extraction of MPs from sludge based on existing analytical methods in the literature, from sampling to quantification and detection. Our laboratory study consists of four protocols used to verify MPs recovery from doped sludge samples containing three polymers (polypropylene, polyethylene terephthalate and nylon). To emphasise the relevance of the optimal protocol, a triplicate test was performed for each of these protocols, all of them using sieve fractions between 100 and 500 μm, while isoporous polycarbonate membranes were used for the filtration of the samples. The percentage polymer distribution of H2O2-enzyme protocol was similar to the control (42% ± 8.49; 38% ± 2.83; 16% ± 11.31), with some limitations for the larger fraction. Data collection was carried out by optical visualisation and chemical identification using Fourier-transform infrared spectroscopy to record polymer spectra obtained for potential interpretation. Finally, a test was conducted to try all protocols on a real sludge from a local plant to confirm their efficiency.

Plastic habitats: Algal biofilms on photic and aphotic plastics

Plastic pollution is abundant in aquatic environments worldwide and many of its detrimental impacts are well documented, but it also represents a novel substrate available to a diversity of organisms. Biofilms – assemblages of bacteria, algae, and fungi – colonise hard surfaces in aquatic environments. They are key agents in biogeochemical cycling and are a food source for grazing organisms, representing a keystone aquatic community, and are known to influence the fate of plastic pollution in aquatic environments. In one of the most temporally thorough assessments of biofilm development on freshwater plastics, here we report on the evolution of algal biofilm assemblages on three plastic polymers (Low Density Polyethylene, Polypropylene, and Polyethylene Terephthalate) over six weeks in the photic and aphotic zones of a freshwater reservoir in Staffordshire, UK. Significant differences were found between diatom assemblages on plastics in the photic and aphotic zones, and between diatom assemblages quantified on weeks 2, 4 and 6 of the study, but total algal photosynthetic pigment concentrations did not vary significantly between polymers in either zone. Scanning Electron Microscopy indicates that degradation of polymer surfaces occurs within six weeks in the aphotic zone, with potential implications for plastic fragmentation and microplastic generation.

Plasma-Induced Hemi-Wicking on Sanded Polymer Surfaces

In this paper, a plasma-induced hemi-wicking phenomenon observed on hydrophobic sanded polymer surfaces, polypropylene (PP), polyethylene terephthalate (PET) and polyethylene (PE) is reported. An atmospheric-pressure argon plasma jet was used to treat a limited area of the carefully sanded polymer surfaces to induce the hemi-wicking phenomenon. Such hemi-wicking triggered by the plasma activation is different from the traditional type, which is achieved purely by the surface topography. Surface analyses by X-ray photoelectron spectroscopy (XPS) and water contact analysis (WCA) show that the combination of sanding and plasma treatment increased the oxygen-to-carbon ratio, which is highly beneficial for surface hydrophilicity. The shear stress tests show that the combination of sanding and plasma treatment can enhance the shear stress by 125%, 95%, and 296% on PP, PET, and PE, respectively. The study shows that the newly developed technique by combining the sanding and plasma processing for polymers could be a potentially useful method in future industry applications.