Polyethylene Terephthalate Polymer Research Articles

Thermal and Mechanical Characterization of the New Functional Composites Used for 3D Printing of Static Mixers.

This paper investigates the possibility of integrating the combination of nanofillers, titanium dioxide (TiO2) and carbon nanotubes (CNT) into the thermoplastic polymer matrix. This combination of fillers can possibly modify the physico-chemical properties of composites compared to the pure polymer matrix. The composites were blended using the extrusion method. The composite filament produced was used to manufacture static mixers on a 3D printer using the additive manufacturing technology fused filament fabrication (FFF). The aim of this work was to inspect the influence of the filler addition on the thermal and mechanical properties of glycol-modified polyethylene terephthalate (PET-G) polymer composites. The fillers were added to the PET-G polymer matrix in several ratios. Tensile test results showed an increase in the overall strength and decrease in the elongation at break of the material. Melt flow rate (MFR) showed a decrease in the viscosity with the initial filler addition and reaching a plateau after 2 wt% filler was added. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) showed minor changes in the thermal properties. Scanning electron microscope (SEM) results showed homogenous distribution of the filler in the matrix and strong filler–matrix adhesion. The results indicate suitable properties of new functional composites for the 3D printing of static mixers for application in tubular reactors.

Evaluation of the polyethylene terephthalate polymer as a modifier of asphalt binder

Evaluation of the polyethylene terephthalate polymer as a modifier of asphalt binder

Intrinsic flame retarding and non-dripping liquid crystal polyethylene terephthalate copolyesters for fire safety system

The notorious issue of high fire hazards, including the generation of considerable heat and melt dripping, is recognized as the bottleneck of extensive use of polyethylene terephthalate (PET). Although various techniques have been adopted for the fabrication of flame retardant PET, how to address the contradiction of flame retardancy and anti-dripping while maintaining its good processability in an environment-friendly method is still challenging. Hence, we design and prepare an intrinsic flame retardant copolyester based on PET and thermotropic liquid crystalline polymer (PET/TLCPx) via a simple and efficient one-step melt copolymerization to address the above challenges. On the one hand, the mesogen units not only allow copolyesters to show a typical liquid crystalline behavior with excellent processability but also constructs a highly rigid main chain to endow PET/TLCPx with outstanding thermal stability, fire resistance, and non-dripping. Furthermore, the resultant PET/TLCP3 exhibits a much lower (by 72 %) peak heat release rate than that of PET, which is attributed to the formation of a denser char layer (char yield ∼ 37 %) for excellent fire resistance. Meanwhile, the melt dripping of PET/TLCPx is suppressed with the increase of complex viscosity and the growth of molecular weight due to the post-condensation during combustion. The resultant high-performance copolyesters are highly valuable for high-end applications that have strict requirements for fire safety and thermal stability, such as fire alarm and rescue systems based on triboelectric effect and shape memory behaviors.

Model analysis on effect of temperature on the solubility of recycling of Polyethylene Terephthalate (PET) plastic

The massive increase in the use of PET plastic bottles has raised the challenge of accumulated waste plastics disposal and its related environmental concerns. Reusing this plastic waste through a solvent-based recycling process seems to be an eco-friendly solution for eliminating waste plastic and converting them into high quality products. The selection of solvent with its temperature requirement for the dissolution of polymeric materials is crucial in the solvent-based recycling process. Therefore, an innovative MATLAB program named HSPs-TPT was designed and constructed in this work to evaluate the dissolving power of solvents. Through this program, the solubility of the waste PET polymer was examined in thirteen (13) different solvents at different temperatures. As a results, the degree of waste PET polymer dissolution in the solvents was presented as the polymer-solvent solubility diagram, which provided the information about the relative energy difference (RED) change with the temperature rise. The program also provided the temperature range effective for the dissolution of PET by indicating the minimum and maximum solubility point for each solvent, which was further validated by the experimental data found in the literature. The proposed MATLAB program can numerically analyse the solubility of a polymer in different solvents in a short time for the recycling process and fabrication of different value-added plastic products such as polymer monoliths and membrane filters.

Molecular-level investigation of plasticization of polyethylene terephthalate (PET) in supercritical carbon dioxide via molecular dynamics simulation.

The current study aims to use the molecular dynamics (MD) simulation method to discuss the glass transition behaviour and fractional free volume (FFV) of the pure polyethylene terephthalate (PET) and the plasticized PET induced by supercritical carbon dioxide (SC-CO2) sorption. The adsorption concentration reproduced through sorption relaxation cycles (SRC) was firstly estimated and in an order of magnitude with the known experimental results available in the reported literature. The FFV induced by SC-CO2 in PET polymer changes regularly, which is proportional to the capacity of SC-CO2 adsorption with the changes in temperature and pressure. The glass transition temperature (Tg) was further estimated to be almost identical to the known experimental values and shows a gradually decreasing tendency with the increase of pressure. Meanwhile, the plasticization of PET polymer studied by radial distribution functions showed that CO2 molecules occupying the sorption sites on the PET backbone promoted plasticization by increasing the fluidity of the PET backbone chain.

Addition of polyvinyl pyrrolidone during density separation with sodium iodide solution improves recovery rate of small microplastics (20–150 μm) from soils and sediments

The purpose of this study was to identify a method to accurately separate small microplastics (<100 μm) from soil and sediment. We initially conducted spike-and-recovery tests using polyethylene microbeads and density separation and found that the recovery rate of microplastic particles smaller than 100 μm was less than 60%. This result suggested that previous reports have underestimated the concentrations of microplastics smaller than 100 μm in soil. When polyvinyl pyrrolidone was added and dispersed in a heavy liquid, the recovery rate exceeded 90%, regardless of the microplastic particle size. This improved recovery rate was independent of the type of polymer (polyethylene, polypropylene, polystyrene, polyethylene terephthalate, or nylon 6) and the physicochemical properties of the soil (Andisols, Entisols, or Ultisols), and the method was also effective for marine and lake sediments. Using this method, we measured microplastic concentrations in paddy soil. The results showed that the most common particle size, 20–100 μm, accounted for 64% of all microplastics. Accurate separation from the soil of fractions smaller than 100 μm, which account for the majority of microplastics in soil, will enable an accurate assessment of the impact of microplastics on the soil ecosystem. The method identified in this study can serve as the basic technique for achieving that goal.

Ultrafast 99% Polyethylene terephthalate depolymerization into value added monomers using sequential glycolysis-hydrolysis under microwave irradiation

Effective and efficient hybrid depolymerisation technologies are emerging as high potential sustainable routes with considerable benefits over conventional recycling methods for the achievement of circular economies for plastics. Herein, combined green and fast glycolysis-hydrolysis depolymerization of polyethylene terephthalate (PET) was carried out under microwave irradiation (MW) with excellent efficiencies. In MW assisted glycolysis of PET, the catalytic activity of two deep eutectic solvents (DES) based on (choline chloride-urea (DES 1)) and (choline chloride-thiourea (DES 2)) was evaluated and compared. Optimised glycolysis conditions were determined using Box Behnken Design (BBD) to attain maximum weight loss of PET, low crystallinity and increased carbonyl index of residual PET. DES volume of 4 mL, 5.5–6 mL of ethylene glycol, and 0.5 min MW irradiation time resulted in a prominent rise in PET weight loss and carbonyl index of residual PET. DES 2 showed an improved catalytic activity than that of DES 1 which is associated to its stronger interaction with EG and PET polymer chains during the course of the reaction. Residual PET obtained post glycolysis reaction was further depolymerized using MW assisted hydrolysis in the presence of weakly basic Na2CO3 and EG. Within 3-minute, the proposed sequential depolymerization technologies facilitated ≈99% conversion of PET to terephthalic acid (TPA), monohydroxyethyl terephthalate (MHET), and bis (2-hydroxyethyl) terephthalate (BHET) monomers produced at a yield of 62.79–80.66%, 17.22–34.79% and 0.54–0.59% respectively. Application on post-consumer PET sample also revealed very satisfactory results with 96.77–98.25% PET conversion and 60.98–78.10% yield of TPA.

Hydrophobic Recovery of Plasma-Hydrophilized Polyethylene Terephthalate Polymers.

Oxygen plasma is widely used for enhancing the wettability of numerous polymers, including polyethylene terephthalate (PET). The treatment with plasma containing oxygen will cause surface functionalization with polar functional groups, which will, in turn, improve the wettability. However, the exact mechanisms leading to the hydrophilic or even super-hydrophilic surface finish are still insufficiently explored. The wettability obtained by plasma treatment is not permanent, since the hydrophobic recovery is usually reported. The mechanisms of hydrophobic recovery are reviewed and explained. Methods for suppressing this effect are disclosed and explained. The recommended treatment which assures stable hydrophilicity of PET samples is the treatment with energetic ions and/or vacuum ultraviolet radiation (VUV). The influence of various plasma species on the formation of the highly hydrophilic surface finish and stability of adequate wettability of PET materials is discussed.

Design of Fuzzy Logic Motion Detection Algorithm for the Bracelet Type Sensor Consisting of Conductive Layer-Polymer Composite Film.

To improve the motion detection performance of a bracelet-type sensor that uses only two tiny sensor modules developed using carbon-based conductive polymer composite films, a fuzzy-logic algorithm was developed in this study. A polyethylene terephthalate polymer film with a conductive layer composed of carbon paste was used as the integral material utilized for the composite film; a small sensor module composed of mechanical parts mounted on the film was developed to effectively detect the surface resistance variations of the film. A participant wore a bracelet sensor, which consisted of two sensor modules, on their forearm, and the resistance variations of the contact area between the forearm and the sensor modules corresponding to the flexion changes of the surface of the body due to muscle contraction and relaxation were detected. The surface resistance variations of the film were converted to voltage signals, which were used as inputs to the fuzzy logic algorithm to detect four consecutive motions of the forearm. The results demonstrated that the fuzzy-logic algorithm attained an accuracy of 94%. The fuzzy algorithm successfully detected four motions and the resting state of the forearms; moreover, it showed improved performance compared to previous research.

Structural Behavior of Reinforced Concrete Beams Containing Pet Waste Particles as Sand Replacement

Abstract This paper examined the polyethylene terephthalate (PET) polymer waste effect that using as a partial replacement for fine aggregate on the R.C beams structural behavior. Six replacement percentages by weight were used in this study: 5 %, 7.5 %, 10 %, 12.5 %, 15 %, and 20 %. Seven concrete beam specimens with dimensions of 150 × 300 × 2300 mm were tested, in which one specimen for each PET replacement percentage was added to the reference specimen. four-point load setting were used to test all specimens via failure load, maximum deflection, energy absorption, stiffness, ductility index, flexural strain, first crack load, and crack pattern. Results showed that raising of PET percentage in the concrete beams leads to an increase in failure load, maximum deflection, ductility index, strain, and energy absorption compared with the reference beam in the ranges 0 – 4 %, 23.2 – 93.7 %, 12.13 – 93 %, 432 – 1139 %, and 51.8 – 275.4 %, whereas its causes a decrease in initial stiffness and secant stiffness in the ranges 5.8 – 38.44 % and 19.2 – 46.4 %. Moreover, crack investigations revealed that the load at which the first crack forms raise when the PET waste content increases.

Functionalization and Modification of Polyethylene Terephthalate Polymer by AgCl Nanoparticles under Ultrasound Irradiation as Bactericidal.

Polyethylene terephthalate polymer (PET) is widely used in diverse areas. In the current study, the surface of PET is modified in two steps in order to improve the quality. At first, the polymer was functionalized with carboxylic groups, and Fourier transform infrared spectroscopy studies were used to verify functionalization. Then, AgCl nanoparticles were synthesized on COOH functional groups on the surface of PET using a sonochemistry method by sequential dipping of the functionalized polymer in an alternating bath of potassium chloride and silver nitrate under ultrasonic irradiation. The effects of ultrasonic irradiation power, the number of dipping steps, and pH on the growth of AgCl nanoparticles as effective parameters on size and density of synthesized Ag nanoparticles were studied. The results of scanning electron microscopy studies showed that the size and density of AgCl nanoparticles under ultrasonic irradiation with a power of 100 W are better than those of AgCl nanoparticles under irradiation with a power of 30 W. Also, by 15 times dipping the polymer into the reagent solutions in pH = 9, the modified polymer with a greater number of nanoparticles with suitable size can be reached. Antibacterial properties of PET containing AgCl nanoparticles were investigated against six Gram-positive and Gram-negative bacteria species, and the results showed significant antibacterial activity, while functionalized PET did not have a significant effect on both types of bacteria.

A Glass Transition Temperatures of PET and PEV Polymers Using Molecular Model Simulations with United Atoms OPLSUA Model

In this study, the glass transition temperature (Tg) of polyethylene terephthalate (PET) and polyethylene vanillate (PEV) are obtained by molecular dynamics (MD) simulations using united atoms OPLS-UA model. The obtained Tg are found to be about 375K and 378K for PET and PEV polymers, respectively, which are a bit higher than those of previous experiments and computer simulation works. This imply the need of parameters optimized and validation to be fit for the specific PET and PEV systems before applied in further works of their blended systems.

Interface Adhesion Property and Laser Ablation Performance of GAP-PET Double-Layer Tape with Plasma Treatment.

In the field of laser ablation micro-propulsion, the property of double-layer tape has significant impact on the propulsion performance. In this paper, low temperature plasma was used to treat the surface of polyethylene terephthalate (PET) to improve its adhesion with energetic polymer. The PET surface pre- and post-plasma treatment was characterized by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM), and the enhancement mechanism of the interface adhesion was discussed. In addition, the ablation performance of the double-layer tape after the plasma treatment was studied. The results showed that the plasma etching effect increased the root mean square roughness of the PET surface from 1.74 nm to 19.10 nm. In addition, after the plasma treatment, the number of C–OH/COOH bonds and O=C–O bonds increased, which also greatly improved the adhesion between the PET and energetic polymers. In the optimization of the ablation performance, the optimal laser pulse width was about 200 μs. The optimal values of the specific impulse (Isp), impulse coupling coefficient (Cm), and ablation efficiency (η) were 390.65 s, 250.82 μN/W, and 48.01%, respectively. The optimization of the adhesion of the double-layer tape and the ablation performance lay the foundation for the engineering application of laser ablation micro-thrusters.

Microbial Consortia and Mixed Plastic Waste: Pangenomic Analysis Reveals Potential for Degradation of Multiple Plastic Types via Previously Identified PET Degrading Bacteria.

The global utilization of single-use, non-biodegradable plastics, such as bottles made of polyethylene terephthalate (PET), has contributed to catastrophic levels of plastic pollution. Fortunately, microbial communities are adapting to assimilate plastic waste. Previously, our work showed a full consortium of five bacteria capable of synergistically degrading PET. Using omics approaches, we identified the key genes implicated in PET degradation within the consortium’s pangenome and transcriptome. This analysis led to the discovery of a novel PETase, EstB, which has been observed to hydrolyze the oligomer BHET and the polymer PET. Besides the genes implicated in PET degradation, many other biodegradation genes were discovered. Over 200 plastic and plasticizer degradation-related genes were discovered through the Plastic Microbial Biodegradation Database (PMBD). Diverse carbon source utilization was observed by a microbial community-based assay, which, paired with an abundant number of plastic- and plasticizer-degrading enzymes, indicates a promising possibility for mixed plastic degradation. Using RNAseq differential analysis, several genes were predicted to be involved in PET degradation, including aldehyde dehydrogenases and several classes of hydrolases. Active transcription of PET monomer metabolism was also observed, including the generation of polyhydroxyalkanoate (PHA)/polyhydroxybutyrate (PHB) biopolymers. These results present an exciting opportunity for the bio-recycling of mixed plastic waste with upcycling potential.

Atmospheric Plasma‐Assisted Deposition and Patterning of Natural Polymers

AbstractPlasma‐assisted deposition is a facile, yet sophisticated method to form biocompatible coatings on materials and introduce specific surface interactions. The plasma process provides unique features such as surface activation, functionalization, and assisted polymerization, all of which can be obtained under low power and room temperature conditions. Plasma‐assisted deposition can further provide coatings with enhanced adhesion and stability. Here, it is reported for the first time, a method for the controlled plasma deposition of the versatile biomaterial chitosan on a range of substrates – soda‐lime glass, metal alloy (Ti4Al6V), thermoplastic polymer (polyethylene terephthalate), and silicone rubber (poly(dimethylsiloxane)). The deposited chitosan films are characterized by atomic force microscopy, scanning electron microscopy and Fourier transform infrared spectroscopy, and evaluated for adhesion and stability. The proposed method is also successfully optimized for the deposition of multiple layers of different biomaterials. Specifically, coatings comprising alternate chitosan and silk fibroin layers are realized, together with patterned surfaces with programmable surface composition. The biological response of the chitosan‐on‐fibroin and fibroin‐on‐chitosan surfaces with and without patterning are investigated using cell culture experiments. Selective area deposition enables the development of improved surface finishes for biomedical devices.

Developing future visions for bio-plastics substituting PET – A backcasting approach

The demand for plastics far exceeds that for any other bulk material and is expected to grow further due to global economic and population growth. Packaging is by far the largest end-user segment for plastics. Interest in bioplastics is increasing as public awareness of plastic waste accumulation in natural environments increases. 2,5-Furandicarboxylic acid (FDCA) is the key monomer in the production of polyethylene 2,5-furandicarboxylate (PEF), a polymer that offers a sustainable solution to replace the commonly used polymer polyethylene terephthalate (PET). A backcasting workshop with 42 experts was held to identify current barriers and challenges that block the commercialization of FDCA-based products and to outline potential pathways toward future market diffusion. Several barriers which are strongly related to technological and market-related aspects are preventing the full potential of FDCA from being unlocked. FDCA products cited in the literature are versatile and cover a wide array of niche applications. In the backcasting workshop, participants described their specific – yet highly divergent – future visions for PEF. Participants with a background in FDCA production referred mostly to developments that would need to take place in the field of FDCA applications to turn their vision into reality, while participants with a background in FDCA product development tended to refer to open issues related to FDCA synthesis. The findings of this study indicate that there is a great need for intensified cross-disciplinary communication and collaboration.

The Role of Ideonella sakaiensis PETase in the Degradation of PET Plastics: a Structural Comparison of the Wild Type and S238F/W159H Double Mutant

Polyethylene terephthalate (PET), a synthetic polymer, is one of the most commonly used plastics today and can be found in over 97% of packaging materials. PET’s durability as a plastic also makes it resistant to biodegradation. According to the National Association for PET Container Resources, only 29.1% of PET packaging waste was recycled in 2018, resulting in 27 million tons of plastic in landfills. These alarming statistics indicate a need for new technology to process discarded PET. A recently discovered bacterium, Ideonella sakaiensis 201‐F6, expresses the enzyme PETase, which binds and hydrolyzes PET. The structure of PETase closely resembles enzymes in the cutinase and lipase families. Similar to cutinases, PETase has an a/β hydrolase fold, but with a more open active‐site cleft. The catalytic residues in the active site of PETase hydrolyze PET plastics into intermediates which are then further broken down by the enzyme MHETase. Wild type PETase breaks down crystalline PET inefficiently, due to the rigid and dense structure of this plastic. In an effort to improve PETase performance, scientists made amino acid substitutions to the PETase active site. As a result, they discovered that the S238F/W159H double mutant narrowed the binding cleft, making the enzyme more active and therefore more efficient. The Pingry School MSOE Center for BioMolecular Modeling MAPS Team used 3‐D modeling and printing technology to examine structure‐function relationships of the PETase wild‐type and S238F/W159H double mutant. These models give an in‐depth view of the structure of PETase and illustrate how it can be utilized to degrade the highly prevalent PET plastic that has littered our planet. Furthermore, comparison of the wild‐type and double mutant structures provides molecular level details about structural changes that can enhance the performance of this enzyme. Gaining this perspective on PETase enzymes could lead to further advances in biotechnology solutions to the degradation of PET and related polymers.

The role of PETase in Breaking Down Polyethylene Plastics

Polyethylene terephthalate (PET) is a synthetic polymer made from chemicals derived from crude oil. As a result of the high volume of plastic produced in the world today, only 9% of all plastics have been recycled while the rest is either dumped in the natural environment or incinerated, leading to problems like plastic pollution and overflowing landfills. PET and other polyesters have been accumulating in the Great Pacific garbage patch. The island of trash causes disturbances in the North Pacific Subtropical Gyre food webs and poses threats towards marine species through entanglement and consumption. While the majority of PET is currently recycled mechanically, this method often consumes high amounts of energy, releases harmful by‐products, and results in a loss of material properties in PET, decreasing the intrinsic value of the polymer. There are also few affordable chemical recycling solutions because of PET’s high resistance to biodegradation, which is due to its structural elements such as its aromatic groups and crystallinity that limit polymer chain movement, generate surface hydrophobicity, and limit its accessibility to ester linkages; making it recalcitrant to catalytic or biological polymerization. In 2016, a bacterium called Ideonella Sakaiensis 201‐F6 was found to have the ability to degrade PET at room temperatures via the secretion of two main enzymes: IsPETase and IsMHETase. IsPETase has a penchant for breaking down crystallized PET over other types of polyester using a wide substrate‐binding pocket. The second enzyme IsMHETase is a hydrolase that has an α/β‐hydrolase domain and a lid domain granting substrate specificity. The degradation process begins when the PET hydrolase (IsPETase) cuts the PET polymer into mono(2‐hydroxyethyl) terephthalate acid (MHET), terephthalate (TPA), and byproduct bis(2‐hydroxyethyl) terephthalate (BHET). Subsequently, the second enzyme MHET hydrolase (IsMHETase) converts MHET into ethylene glycol and TPA. The end products can then be used in further applications such as making antifreeze and hybrid materials for plastic carrier bags, or simply be broken down by microorganisms into carbon dioxide and water. There are, however, concerns about the large‐scale application of microorganisms such as I. Sakaiensis for industrial recycling purposes, as the process is time consuming and often unreliable. Researchers have therefore begun looking at protein engineering as a means to allow enzymes like IsPETase and IsMHETase to be more efficient and degrade PET 100‐1000x faster. Some proposed solutions include narrowing the active‐site cleft, combining multiple PET‐active enzymes, and further lowering the protein’s optimal reaction temperature.The Ashbury College MSOE Center for BioMolecular Modeling A Protein Story (MAPS) team uses 3D modelling and printing technology to examine structure‐function relationships of the enzymes PETase and MHETase involved in the PET degradation process.

Effect of plastic pollution in soil properties and growth of grass species in semi-arid regions: a laboratory experiment.

Since the year 2020, the use of plastic as a strategy to mitigate the spread of COVID-19 disease has been given substantial attention. Global environmental contamination of plastic creates waste and is a known threat to soil ecosystems as a main sink of microplastics. However, there is still considerable uncertainty about microplastics controlling soil properties alteration. Therefore, we carried out an incubation experiment with soil and Carex stenophylla Wahlenb., which are the dominant soil and grass species in semi-arid regions. We investigated the effect of polymer polyethylene terephthalate (PET) concentrations (0%, 1%, 3%, and 5%) on C. stenophylla growth and soil ammonium-N and nitrate–N, organic matter content, pH, soil aggregates, and soil respiration. When soils were exposed to PET microplastics, fewer seeds germinated (62.8 ± 32%) but not significantly (p value > 0.05) when soils were treated to 0, 1, 3, and 0.5% PET. Shoot height was also not effectively reduced with PET. The soil pH was considerably lower when exposed to higher PET compared to all other treatments with the soil exposed to 5% w/w PET for both unplanted and planted, being 0.84 and 0.54 units, respectively, lower than the controls. The soil microbial respiration under exposure to PET was considerably increased in comparison to control samples. Moreover, the presence of PET resulted in potential alterations of soil stability, and with PET present soil stability increased. In conclusion, PET microplastics cannot significantly affect the development of C. stenophylla but could affect crucial soil properties. In addition, changes occurred with increased variability in soil ammonium-N and nitrate–N, particularly at a high PET ratio.

All-Atom Molecular Dynamics Simulations on a Single Chain of PET and PEV Polymers.

Polyethylene vanillic (PEV), a bio-based material, has mechanical and thermal properties similar to polyethylene terephthalate (PET), the most common polymer used in industries. The present study aimed to investigate and compare their structural dynamics and physical data using a computational approach. The simple model of a single-chain polymer containing 100 repeating units was performed by all-atom molecular dynamics (MD) simulations with refined OPLS–AA force field parameters. As a result, the flexibility of the PEV structure was greater than that of PET. PET and PEV polymers had the predicted glass transition temperature Tg values of approximately 345 K and 353 K, respectively. PEV showed a slightly higher Tg than PET, consistent with current experimental evidence.