Poly Ethylene Terephthalate Powder Research Articles

An experimental investigation and response surface methodology-based modeling for predicting and optimizing the rheological and mechanical properties of self-compacting concrete containing steel fiber and PET

In this study, rheological and mechanical properties of self-compacting concrete containing polyethylene terephthalate (PET) and steel fibers have been investigated experimentally and numerically. A total of 30 mixing schemes are investigated using a response surface (RSM) method. Input variables in the mixtures include PET as a substitute for part of the fine aggregates, steel fibers, stone powder as a substitute for a percentage of cement and superplasticizer. The PET, steel fibers and stone powder quantity in the concrete were in the range of 0–16% of the fine aggregates, 0–0.4% of the concrete volume, and 0–16% of cement weight, respectively. The superplasticizer quantity was 0.5–1.5% of the weight of powder materials. An optimum mixture was determined using RSM optimization technique.To evaluate the rheological specifications, slump flow, T50, V funnel, and l-box tests were used in the experiments. For the mechanical specifications, compressive strength, tensile strength, flexural strength, and stress–strain curve were used. Experimental results show that steel fibers reduce rheological properties while improve mechanical properties, especially ductility. Additionally, PET increases the corresponding strain of maximum compressive strength of concrete (ε0) and ductile fracture. The optimization results indicate that with 4% PET, 0.23% fiber, 6.47% stone powder, and 1.132% superplasticizer, the maximum 28-day compressive strength is obtained, while meeting EFNARC workability indicators.

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.

Potential one-step strategy for PET degradation and PHB biosynthesis through co-cultivation of two engineered microorganisms

The management and recycling of plastic waste is a challenging global issue. Polyethylene terephthalate (PET), one of the most widely used synthetic plastics, can be hydrolyzed by a series of enzymes. However, upcycling the resulting monomers is also a problem. In this study, we designed a co-cultivation system, in which PET degradation was coupled with polyhydroxybutyrate (PHB) production. First, PETase from Ideonalla sakaiensis was expressed in Yarrowia lipolytica Po1f with a signal peptide from lipase. The engineered PETase-producing Y. lipolytica was confirmed to hydrolyze bis(2-hydroxyethyl) terephthalate (BHET) and PET powder into the monomers terephthalate (TPA) and ethylene glycol (EG). Simultaneously, a TPA-degrading Pseudomonas stutzeri strain isolated from PET waste was transformed with a recombinant plasmid containing the phbCAB operon from Ralstonia eutropha, which encodes enzymes for the biosynthesis of PHB. The two co-cultivated engineered microbes could directly hydrolyze BHET to produce the bioplastic PHB in one fermentation step. During this process, 5.16 g/L BHET was hydrolyzed in 12 h, and 3.66 wt% PHB (3.54 g/L cell dry weight) accumulated in 54 h. A total of 0.31g/L TPA was produced from the hydrolyzation of PET in 228 h. Although PHB could not be synthesized directly from PET because of the low hydrolyzing efficiency of PETase, this study provides a new strategy for the biodegradation and upcycling of PET waste by artificial microflora.

Influence of Polyethylene Terephthalate Powder on Hydration of Portland Cement.

The management of plastic waste is a massive challenge and the recycling of plastics for newer applications is a potential solution. This study investigates the feasibility of using polyethylene terephthalate (PET) powder in cementitious composites. The changes in the strength and microstructure of Portland cement incorporating PET powder with different replacement ratios were systematically analyzed through the measurements of compressive strength, isothermal calorimetry, X-ray diffraction, thermogravimetric analysis, and Raman spectroscopy. In addition, the possible chemical changes of cement paste samples were studied upon exposure to different conditions, including deionized water, seawater, and simulated pore solution. Based on the test results and analysis, no apparent chemical changes were observed in the cement paste samples, regardless of the exposure conditions. In contrast, the PET powder incorporated into concrete exhibited remarkable changes, which may have occurred during the mixing process. The results also suggested that the maximum replacement ratio of PET powder should be less than 10% of the binder (by mass) to minimize its influence on cement hydration, due to the interaction between water and PET. The PET-containing samples showed the presence of calcium aluminate hydrates which were absent in the neat paste sample.

Designing of high-performance epoxy adhesive with recycled polymers and silica nano particles (SNPs) in epoxy/carbon fiber composite-steel bonded joints: Mechanical properties, thermal stability and toughening mechanisms

In this study, the effect of hybrid reinforcement comprising silica nanoparticles (SNPs) and a blend of equal percentages of acrylamide-modified waste tire powder and polyethylene terephthalate (PET) on mechanical, thermal stability, and microstructure of the epoxy-phenolic adhesive was assessed using tensile test, TGA, and FESEM tests, respectively. To investigate the adhesion features, the formulated adhesive was applied in lap joint bonding of a stainless steel 316L to epoxy resin/carbon fiber composite. Based on the tensile test results, adding 10 wt.% modified waste tire powder- PET blend and 1 wt.% SNPs to the epoxy-phenolic adhesive increased the tensile strength, modulus, and the toughness of the dumbbell-shaped samples by 65.24%, 58.95% and 98.80% as compared with the neat epoxy-phenolic adhesive, respectively. Furthermore, the highest improvement of shear strength, modulus, and toughness in the steel-composite single lap joint was observed in the sample containing 10 wt.% modified waste tire powder-PET blend and 0.5 wt.% SNPs of 237.22%, 25.64%, and 279.66%. TGA results also indicated that the addition of 10 wt.% PET powder and 1 wt.% SNPs enhanced the initial decomposition temperature, maximum decomposition temperature, and residue char by 5.94°C, 3.64°C, and 59.45% respectively. The images of the fracture surface of the optimal samples in the tensile test showed that the debonding of nanoparticles, plastic void growth, and deviation from the main crack path are among the major mechanisms in the increase of the toughness of the samples.

A suspension-based assay and comparative detection methods for characterization of polyethylene terephthalate hydrolases

Enzymatic breakdown of plastic has emerged as a promising green technology, and its implementation will require assays that are accurate, reliable and convenient. Here, we assess two principles to monitor the hydrolysis of the common polyester, polyethylene terephthalate (PET). Hydrolysis of PET gives rise to heterogeneous products of different sizes and solubility, and as a result, specific experimental methods detect different activity levels. To avoid errors and to get a thorough picture of enzyme reactions, it is beneficial to combine several detection techniques. The two methods described herein are quantitative and complementary, and detect respectively the amount of soluble aromatic products and the formation of the constitutive aromatic monomers. A combined quantification approach identifies pitfalls in the characterization of these enzymes and provides mechanistic insight, but for screening and/or comparative studies of PET hydrolases we recommend a plate reader-based assay with suspended PET powder. This assay is rapid and simple, but still provides a good measure of the initial rates, which may be used in comparative biochemical analyses of these enzymes.

Preliminary Study on Compressive Strength of Porous Asphalt Containing Modified Buton Asphalt, Waste Plastic and Limestone Powder

Porous asphalt is a surface layer or a wear layer is one of the asphalt material developed to overcome the problem of inundation during the rainy season making it suitable for use in Indonesia which has high rainfall intensity. Furthermore, it is necessary to optimize the use of a number of natural resources in Indonesia such as natural rock asphalt in Buton Island (BRA) and limestone which is available in many places. In addition, reducing of plastic waste is attracts the attention of a number of countries including Indonesia. This paper is part of a series of investigate study related to the behaviour of porous asphalt mixture made with modified Buton asphalt (MBA), waste plastic and lime stone powder. The compaction results showed good adhesion can unite the waste Polyethylene terephthalate (PET), limestone powder and coarse aggregate particles. There is no visible negative effect of waste PET and limestone powder in porous asphalt mixture against compressive strength.

Characterization of Recycled Polyethylene Terephthalate Powder for 3D Printing Feedstock

This paper assessed the suitability of PET powder produced by crushing used plastic bottles as 3D printing feedstock. Characterization of the powder was done through determining its flow property, coefficient of friction, bulk density, flexural and tensile strengths and compared with those of ABS, PLA, PVA, Nylon and HDPE which are used conventionally 3D printing of plastic parts. Two grades of PET bottles were used in this study: grade one which is designated PET1 with intrinsic viscosity values ranging from 0.78-0.80 (used for water bottles) and grade two which is designated PET2 with intrinsic viscosity values ranging from 0.80-0.85 (used for carbonated drinks bottles). The results of the tests performed showed that PET1 has bulk density, coefficient of friction, flexural strength and tensile strength values of 0.16 g/m3, 0.43, 82.1 MPa and 63.4 MPa respectively while PET2 has bulk density, coefficient of friction, flexural strength and tensile strength values of 0.15 g/m3, 0.22, 82.7 MPa and 57.8 MPa respectively. The Experimental results show that both PET1 and PET2 have very good flow property, and are suitable for 3D printing. This study solves two major problems: plastic waste management and availability of locally produced 3D printing feedstock, which is currently the greatest challenge of 3D printing in Nigeria. Keywords— 3D printing feedstock, Characterization, Intrinsic viscosity, PET powder.

The re-usability of heat-exposed poly (ethylene terephthalate) powder for laser sintering

Selective laser sintering, also called laser sintering (LS), is an additive manufacturing process that requires micronized plastic powder. Recently, we showed poly (ethylene terephthalate (PET) powder is a suitable material for LS, with a comparable printing performance as the current front-runner, polyamide 12 (PA12). However, the LS process, by its nature, leaves unused powder that has been exposed to heat for prolonged time, and this powder may not be fully re-usable due to degradation.In this work, the re-use potential of heat-exposed PET powder is established. This is a matter of crucial importance as powders suitable for LS are very expensive, and the powder left after a building episode has to be re-used. Heat-exposed PA12 has to be blended or refreshed with virgin powder, to avoid printing defects. In contrast, heat-exposed PET powder, after 96 h at 210 °C, could be used, without refreshing with a portion of virgin powder. The printed articles from heat-exposed powders were as good as those from the fresh powder. There was no cross-linking and there was only a minor increase in the molecular weight of the powder after 96 h, at 210 °C.

Chemical and Biological Treatment of Plastic Wastes by Bacteria Isolated from Contaminated Soils in Baghdad, Iraq

Due to the rapid increasing of polyethylene terephthalate (PET) used in industries, there are large of wastes quantities inter the stream per year which make a serious problem to water environment. In this work, the chemical treatment involve plastic bottles pieces mixed with MgO nano-catalyst, the result was white powder of polyethylene terephthalate (PET) which was used in this study. This work aims to isolate and screen bacterial isolates that able to degrade PET powder. Thirty eight bacterial isolates have been isolated from different waste disposal sites in Baghdad city. These isolates were screened on minimal salt media (MSM) plates according to clear zone method and the change in indicator color by using PET powder as the sole source of carbon and energy. According to morphological, biochemical characteristic, and analysis by Vitek 2 the most active isolates were identified as Acinetobacter baumannii.

Micronization of polyethylene terephthalate via freezing of highly sheared emulsions of polyethylene terephthalate in saturated liquid tetrahydrofuran

AbstractA novel technique for micronizing polyethylene terephthalate (PET) resin (∼ 3 mm) with saturated liquid tetrahydrofuran (THF) has been developed. PET pellets were introduced to a high‐pressure vessel filled halfway with THF at loadings up to ∼ 7 wt % PET. When the vessel was closed and heated, the PET pellets exhibited significant melting point depression at 190°C in saturated liquid THF at 17.1 bar. Although other organic solvents were also able to depress the melting point of PET, only THF was able to facilitate the formation of an emulsion of PET‐rich liquid droplets in the saturated liquid solvent when the mixture was agitated. In an attempt to generate the smallest possible PET droplets, a high‐speed (5000 rpm), close‐clearance, radial flow impeller was used to shear and disperse the droplets at ∼ 200°C and 20.1 bar. Emulsion was rapidly cooled while mixing. The PET droplets froze at ∼ 190°C, and the vessel was then cooled to ambient temperature. The excess liquid THF was decanted, and the PET particles were dried in a vacuum oven to remove residual THF. The PET particle sizes ranged between 2 and 70 μm, with number, area, and volume average diameters of 6, 20, and 30 μm, respectively. A comparison between the PET resin and PET powder properties indicated that the micronization reduced the Mw from 32,700 to 22,800. DSC results suggest that the rapid quench leads to a morphology different from equilibrium, with small somewhat imperfect crystallites, a lower overall degree of crystallinity, and a suppressed ΔCp at the glass transition. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

The Partial Replacement of Halloysite Nanotubes (HNTs) and Precipitated Silica by Recycled Poly(ethylene Terephthalate) Powder on Cure Behavior, Tensile Properties and Morphology of Natural Rubber Composites

In this article, halloysite nanotubes (HNTs) and precipitated silica were replaced by recycled polyethylene terephthalate powder (R-PET) in natural rubber composites. Five different compositions of NR/HNTs/R-PET and NR/Silica/R-PET composites [i.e. 100/20/0, 100/15/5, 100/10/10, 100/5/15, and 100/0/20 parts per hundred rubber (phr)] were prepared on a two-roll-mill. Comparison of the curing behavior, tensile properties, and morphological characteristics of natural rubber composites was studied. The results indicated that the replacement of HNTs and silica by R-PET decreased the tensile strength, tensile modulus, and elongation at break of composites, but NR/Silica/R-PET composites showed the lower trend than that NR/HNTs/R-PET did. The negative effect of these properties could be explained by the decrement of crosslink density, R-PET is unable to be transferred the stress due to the weal rubber-fillers interactions, and the reducing of ductility of rubber matrix. The curing results revealed that, with replacement of HNTs and Silica by R-PET, the scorch time (ts2) and cure time (tc90) were decreased. Scanning electron microscopy investigation of tensile fracture surfaces confirmed that co-incorporation of NR/HNTs/R-PET would improve the dispersion of R-PET and enhanced the interactions between fillers and NR matrix rather than NR/Silica/R-PET composites.

The Influence of Recycled Poly(ethylene Terephthalate) Powder on Fatigue Life, Thermal Stability, and Morphology of Halloysite Nanotubes (HNTs) and Precipitated Silica Filled Natural Rubber Composites

In this paper, the influence of recycled polyethylene terephthalate powder (R-PET) on fatigue life, thermal properties and micro-fracture surfaces of halloysite nanotubes (HNTs) and silica filled natural rubber composites have been studied. The total amount of hybrid filler in each formulation was kept constant at 20 parts per hundred rubber (phr). The final properties of HNTs/R-PET and Silica/R-PET compounds are considered separately and comparatively. Results indicated that the fatigue life of the natural rubber composites decreased with the replacement of these two fillers by R-PET powder. This observation might be due to the R-PET itself, which reduces the interfacial adhesion and wettability between rubber matrix and fillers. By replacing of HNTs and silica with R-PET powder, the thermal degradation of natural rubber composites was shifted to a lower temperature and the char residues was decreased, in which HNTs/R-PET composites expressed the higher temperature and char residues than silica/R-PET composites. This findings may be due to the HNTs/R-PET has less volatile matter than silica/R-PET that might enhance the degradation temperature of the natural rubber composites. SEM micrographs also exhibited weak interfacial adhesion when these two fillers were replaced with R-PET powder in NR composites.

Evaluation of possibilities for using off-grade polyethylene terephthalate in friction joints

The physicomechanical and triboengineering properties of off-grade polyethylene terephthalate (PETP) and composites on its base are studied. It is shown that the coatings produced from off-grade PETP powder are on a par with the ones obtained from the branded stock of this polymer. Modification of PETP by organic and inorganic additives makes it possible to obtain composites for antifrictional purposes. The coatings from off-grade PETP composites are not inferior to their analogues on the polyamide-6 base in their triboengineering characteristics, and even surpass them in such properties as moisture absorption and stability of their adhesive bonding to metals.

Production and characterization of thermally sprayed polyethylene terephthalate coatings

Thermally sprayed polymer coatings are increasing in importance as protection against corrosion and wear. In this work, polyethylene terephthalate (PET) powder was deposited on 1020 steel by low-velocity flame spray technology. A potential application of this coating is to provide protection against corrosion in automobile fuel tanks, which are nowadays made of lead–tin-coated steel. In spite of the good properties presented by the lead–tin coatings, environmental cost restrictions have limited the use of heavy metals, encouraging research in new materials to substitute them. PET powder was obtained from post-consumer beverage bottles. Concerning the coating process, the following parameters were investigated: substrate pre-heating temperature, oxygen/propane flow rate ratio and spray distance. It was observed that the temperature attained by the PET during the deposition significantly affects the characteristics and properties of the coating. Chemical and structural changes of PET due to the thermal spray processing were investigated by Fourier transform infrared spectroscopy, differential scanning calorimetry and intrinsic viscosity analysis. The corrosion resistance of the coating was evaluated by total and partial immersion tests in gasoline, diesel oil and alcohol. No coating damage was detected.

Production and characterization of thermally sprayed polyethylene terephthalate coatings

Thermally sprayed polymer coatings are increasing in importance as protection against corrosion and wear. In this work, polyethylene terephthalate (PET) powder was deposited on 1020 steel by low-velocity flame spray technology. A potential application of this coating is to provide protection against corrosion in automobile fuel tanks, which are nowadays made of lead–tin-coated steel. In spite of the good properties presented by the lead–tin coatings, environmental cost restrictions have limited the use of heavy metals, encouraging research in new materials to substitute them. PET powder was obtained from post-consumer beverage bottles. Concerning the coating process, the following parameters were investigated: substrate pre-heating temperature, oxygen/propane flow rate ratio and spray distance. It was observed that the temperature attained by the PET during the deposition significantly affects the characteristics and properties of the coating. Chemical and structural changes of PET due to the thermal spray processing were investigated by Fourier transform infrared spectroscopy, differential scanning calorimetry and intrinsic viscosity analysis. The corrosion resistance of the coating was evaluated by total and partial immersion tests in gasoline, diesel oil and alcohol. No coating damage was detected.

多孔質フライアッシュの組織制御とゼオライト化による強度変化

The porous fly-ash ceramics with various porosity were prepared using colloidal process with molten wax. Polyethylene terephthalate powders were used combustible pore-forming agents. The total porosity of porous fly-ash increased with the polyethylene terephthalate powder content. The flexural strength of porous fly-ash drastically decreased as the total porosity increased. By the treatment of the sintered fly-ash with 3mol/dm3 NaOH solution at 383K for 15h, phillipsite, a kind of zeolite, was formed on the sintered fly-ash surface. The flexural strength of sintered fly-ash decreased to half of the original value by the zeolitization treatment.

The effect of mechanical pretreatment of polyethylene terephthalate powder on the structural and mechanical properties of coatings made from it

The effect of mechanical pretreatment of polyethylene terephthalate powder on the structural and mechanical properties of coatings made from it