Poly Ethylene Terephthalate Blends Research Articles

Co-pyrolysis of plastic waste and macroalgae Ulva lactuca, a sustainable valorization approach towards the production of bio-oil and biochar

To address the pressing demand for sustainable energy in light of environmental challenges, this study explored the synergetic effects of the co-pyrolysis of polyethylene terephthalate (PET) and Ulva lactuca macroalgae to yield bio-oil and biochar. The objective is to enhance the bio-oil quality for wider usability and to combat marine pollution. By employing co-pyrolysis, notable progress has been achieved in bio-oil yield and quality, particularly in hydrocarbon content, through the integration of PET. The highest bio-oil yield of 37.91 % was achieved under optimal conditions at 500 °C with a feedstock mixture consisting of 40 % U. lactuca and 60 % PET. Under these conditions, the bio-oil exhibited a significant increase in hydrocarbon content, reaching 57.16 %, which is essential for improving its energy potential. Biochar quality was also enhanced, with the biochar from a 70 % U. lactuca and 30 % PET blend showing a BET surface area of 20.18 m2/g, compared to the initial 1.38 m2/g of raw U. lactuca, indicating improved surface properties. This study presents a sustainable energy generation and environmental preservation approach, underscoring the potential of synergistically utilizing marine resources and plastic waste.

Endothermic–Exothermic Hybrid Foaming of Recycled PET Blends

Over the past decades, the use of polyethylene terephthalate (PET) has seen significant growth, particularly in the packaging industry. However, its long decomposition time poses serious environmental challenges. The aim of this research was to develop a process for the foaming of large quantities of recycled PET (rPET) using endothermic and exothermic foaming agents. Various formulations with different ratios of endothermic and exothermic foaming agents were prepared, as well as their mixtures. The study found that the endothermic–exothermic hybrid foaming process resulted in a finer cell-size distribution and enhanced mechanical properties, making the foams highly suitable for widespread applications. The results support the potential use of exothermic foaming agents as nucleating agents in a hybrid foaming system. In particular, the ratio of 3% endothermic and 1% exothermic foaming agents proved optimal in terms of achieving a balance between porosity and mechanical strength, thereby enabling broad industrial applicability.

Direct 3D Printing of Recycled PET/PP Granules by Shear Screw Extrusion.

This article introduces a one-step extrusion-based fused deposition modeling (FDM) approach for the challenging separation of polypropylene (PP) and polyethylene terephthalate (PET) during recycling. A shear screw printer (SSP) with shear elements was designed, and it was compared to a conventional single-screw printer (CSP) to investigate the differences in print stability, degradation levels, tensile performance, molecular orientation, and crystallization when preparing recycled PP and recycled PET blends. Although the retention effect of the SSP screw slightly increases the degradation of the blended rPP/rPET, the strong shear (2.6 × 104 s-1) applied near the extrusion exit improves the blending efficiency. The SSP also enhances molecular orientation, modulus of the parts, and reduces performance fluctuations. Additionally, the SSP has the potential to simplify the recycling process, enabling the transformation of blended recycled materials into products with just one melt process.

Selective depolymerization of PET to monomers from its waste blends and composites at ambient temperature

Recycling of polyethylene terephthalate (PET), one of the largest varieties of synthetic polymers and the primary textile feedstock, presents a significant challenge when waste PET blends or composites are involved. Despite numerous efforts to address waste PET, it is difficult to achieve energy-efficient and selective depolymerization of PET through physical sorting systems or existing chemical means. Herein, we report a dichloromethane (DCM) and ethanol (EtOH) solvent system to selectively depolymerize PET into monomers while fully recover other mixture components. The complete depolymerization of PET and recovery of more than 99% of terephthalic acid (TPA) monomer can be achieved at room temperature within 30 min. After the reaction, TPA can be separated by simple filtration due to its insolubility in the solution. The filtrate can be reused for the recovery of PET. Molecular dynamics simulation shows that the high activity and selectivity is attributed to activating effect of DCM to PET ester groups, as well as pore-forming effect to promote PET interfacial mass transfer. Environmental energy impact and carbon emissions were evaluated and the results demonstrate the environmental friendliness of this method. This approach enables direct and efficient recycling of PET monomers from waste blends and composites, providing a viable solution to plastic and textile pollution.

Crystallization, Rheological and Thermally Conductive Behaviors of Polymethyl Methacrylate/Recycled Polyethylene Terephthalate Blends: An Evolutional Study Based upon Hierarchically Structural Analysis

Crystallization, Rheological and Thermally Conductive Behaviors of Polymethyl Methacrylate/Recycled Polyethylene Terephthalate Blends: An Evolutional Study Based upon Hierarchically Structural Analysis

Study of mechanical and rheological properties, morphology, and miscibility in polylactid acid blends with thermoplastic polymers

AbstractBlends of polypropylene, polystyrene (PS), polyethylene terephthalate (PET), and high‐, low‐ and linear low‐density polyethylene (LDPE and LLDPE) with different contents on polylactid acid (PLA) were prepared. Tensile and impact properties and melt flow rate (MFR) of the mixtures were determined. Morphology was analyzed through scanning electron microscopy (SEM) and interactions were studied by measuring glass transition temperatures (Tg) as well as applying a model to quantify the composition dependence of tensile strength. Results show that there are significant differences on structure and properties among the blends. Polyolefin based blends feature heterogeneous structures with big particle sizes, which translates to blend properties with high negative deviation from the rule of mixtures (ROM), especially for LDPE and LLDPE. Blends of PET and PS feature smaller dispersed particles, resulting in blends with mechanical properties close to those of ROM. Shifting in glass transition temperatures indicate interactions between these materials, which were quantitatively determined indicating the strongest interactions for the PS/PLA pair followed by the PET/PLA mixture.

IDENTIFICATION OF BIODEGRADABLE POLYMERS AS CONTAMINANTS IN THE THERMOPLASTICS RECYCLING PROCESS

In this work, the presence of biodegradable polymers in recycled plastic materials was characterized using readily available techniques. Recycled polypropylene (PP), polystyrene (PS) and polyethylene terephthalate (PET) were studied. The contamination of these plastics with polylactic acid (PLA), polyhydroxybutyrate (PHB) and thermoplastic starch (TPS) was simulated using 10 wt.% of the contaminant. Fourier transform infrared spectrometry (FTIR) and differential scanning calorimetry (DSC) were used as characterization techniques. In addition, the effect of aging on recycled products from PET blends contaminated with TPS and PHB was studied. The results show changes in the intensity of the FTIR spectra bands of the PS and PP blends contaminated with biodegradable polymers. By DSC, changes in the cold crystallization peak of recycled PET are observed when mixed with TPS and PHB. When the contaminant is PLA, the changes are masked due to the thermal characteristics of both materials. In PS, changes in the calorimetric curves are identified by the presence of PLA and PHB. Contamination with PLA, PHB and TPS hinders the processing of recycled PET after one year of storage due to the aging of the material.

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.

Enhancement of the fatigue life of recycled PP by incorporation of recycled opaque PET collected from household milk bottle wastes

Opaque PET (Polyethylene terephthalate) was recently introduced as a dairy packaging, mainly for milk bottles. Opaque PET, obtained as PET filled with mineral nanoparticles, allows for a reduction of bottles’ thickness, thus a cost reduction for industrials. For this reason, the use of opaque PET is steadily increasing. However, its recyclability is nowadays an issue: although the recycling channels are well established for transparent PET, the presence of opaque PET in the household wastes weakens the existing recycling channels. Besides, many initiatives are launched in Europe to turn wastes into resources, as one key to a more circular economy. One of the biggest challenges is an efficient sorting of the plastic solid wastes since the PET is not miscible with other plastics such as polypropylene (PP) from the bottle caps and polyethylene (PE) from the other milk bottles.In this work, the mechanical properties of uncompatibilized blends of opaque PET (rPET-O) with recycled polypropylene (rPP) have been studied; both are collected from household wastes. The tensile properties and the fatigue life of rPP, monitored by in-situ digital image correlation and in-situ infrared thermography, are increased by the incorporation of rPET-O. rPET-O/rPP blends may be substituted to rPP for similar applications, with no need to sort the caps from the bottles. Thus, as a concept, the incorporation of opaque PET into the PP recycling sector may be a new route to absorb some of the growing amounts of opaque PET.

Impact Strength and Morphology of Sustainably Sourced Recycling Polyethylene Terephthalate Blends

Polyethylene terephthalate (PET) is a semi-crystalline material that is widely used in the packaging industry, mainly in the production of bottles for beverages. Similar to other plastics, PET causes a problem in disposal as it remains in the environment for a long time. Most of the bottles are thrown away after a single usage, which worsens the disposal problem. Recycling is one of the best ways to reduce the problem of disposal. However, recycling reduces the mechanical and chemical properties of the PET. Factors such as moisture absorption, biological pollutants, oxidation, high temperature, and thermal degradation have reduced the molecular weight of PET. To improve the properties, recycled PET had been blended with Polyamide 11 (PA11) at different ratios of PET: PA11, 30:70, 50:50, and 70:30. A modified styrene/acrylic/epoxy chain extender (Joncryl) was added at 1 wt % in the blend to enhance the properties. The properties of recycled PET/PA11 blends were investigated in terms of mechanical and morphological aspects. The impact strength of recycled PET/PA11 blend at the ratio of 30/70 had recorded the highest impact strength of 54.67 J/m, owing to the good impact property of PA11. The addition of 1 wt % modified styrene-acrylic chain extender (Joncryl) had further enhanced the impact strength of the blends. The findings were supported by the morphologies analyses that showed the existence of the co-continues phases and less pull out effect of particles with the addition of Joncryl. Recycled PET/PA11 blends have potentials to be used in various applications that related to the structural application of automotive and construction.

Shakedown analysis of PET blends with demolition waste as pavement base/subbase materials using experimental and neural network methods

Recycling and reusing construction and demolition (C&D) wastes for civil engineering construction activities has been identified as an energy-saving and sustainable solution. The purpose of this study is to evaluate the deformation behavior of two types of C&D waste materials, namely recycled concrete aggregate (RCA) and crushed brick (CB) when mixed with polyethylene terephthalate (PET) plastic waste. RCA and CB were mixed with 1%, 3%, 5%, and 7% of PET, and the permanent deformation behavior of the blends was evaluated using repeated load triaxial (RLT) test. The shakedown criterion was utilized for identifying the deformation behavior of blends. Most of the PET/RCA and PET/CB blends exhibited Range B (plastic creep) and Range C (incremental collapse) response, respectively, in the investigated stress levels. Shakedown analysis of the test results indicated that up to 3% PET could be mixed with RCA for base/subbase applications, while CB should be mixed with 1% PET, in the subbase layer. Artificial neural network (ANN) method was next used to simulate the permanent strain and shakedown behavior of the blends with consideration of the physical properties and stress states. The ANN model was found to be highly efficient for simulating the permanent strain graph and identifying the shakedown behavior of the blends. A sensitivity analysis was subsequently performed to investigate the impact of input variables on the permanent deformation behavior and the results indicated that number of cycles and confining stress were the most important factors.

Preparation and characterization of PET/SEBS incorporated with organomontmorillonite

This study is focused on the characterization of polyethylene terephthalate (PET)/Styrene-Ethylene-Butylene-Styrene (SEBS)/Organomontmorillonite (OMMT) blends. SEBS-g-MA is used as compatibilizer and SEBS is the impact modifier at 30 %wt. The compounds were blended by twin-screw extruder and molded for test specimen by injection molding. The effect of OMMT types (Cloisite15A and Cloisite30B) and contents (1 and 3 %w/w) on properties of PET blends with SEBS and SEBS-g-MA were investigated. The PET composites incorporated with Cloisite15A had higher impact strength and %elongation at break whereas lower tensile strength than the one with Cloisite30B. Comparing with PET/SEBS/SEBS-g-MA blends, adding OMMT into PET/SEBS/SEBS-g-MA would increase thermal property. However, it had no significant changes with higher OMMT. %Crystallinity of PET would be increased with OMMT contents. PET/SEBS/SEBS-g-MA had lower %LOI but higher burning rate compared with PET. However, the addition of OMMT could improve flame retardant properties of PET blends. Addition of Cloisite15A and Cloisite30B into PET/SEBS/SEBS-g-MA increased %LOI. From UL 94 tests, polymer composites could be classified in HB class. The burning rate of polymer composites was decreased with increasing OMMT due to decomposition of OMMT act as a barrier to inhibit combustion.

Study of thermal, morphological, barrier and viscoelastic properties of PP grafted with maleic anhydride (PP-g-MAH) and PET blends

Properties of polyethylene terephthalate (PET) and polypropylene (PP) can be enhanced by blending both in a specific proportion to get combined superior properties. To make a homogeneous blend, maleic anhydride functionalized PP (PP-g-MAH) was used as a compatibilizer in 60% PET blends. In all blends, PET’s percentage crystallinity was reduced as compared to pure PET because there were hindrances in chains packing because of the presence of PP chains. The addition of compatibilizer in PET and PP blend enhanced interactions resulted in a homogeneous blend with fewer voids. 2.5% of PP-g-MAH was observed to be the optimum value of compatibilizer in the blend of PET and PP. The decrease in free space inside the blend hindered water molecules' passage through the sheets. Owing to this, water vapor permeability of the blend was less compared to pure PET. The addition of the nonpolar PP also influenced the water transmittance rate of blended sheets.

Stiffness and flexural strength evaluation of cement stabilized PET blends with demolition wastes

This study was conducted to assess the performance of cement stabilized polyethylene terephthalate (PET) blends with construction and demolition (C&D) waste, namely recycled concrete aggregate (RCA) and crushed brick (CB), as a pavement construction material. A suite of basic characterization tests was undertaken on 3% and 5% PET blends (by mass) with RCA and CB stabilized with 3% cement. The material strength evaluation of the PET blends were undertaken using unconfined compressive strength (UCS) test and the secant modulus results of the blends were also analyzed. Moreover, the resilient moduli (MR) characteristics were evaluated by repeated load triaxial (RLT) test while the flexural strength and the fatigue life of the blends were evaluated by flexural beam tests. UCS results of the cement stabilized PET blends of RCA and CB satisfied the minimum requirement for 7 days of curing samples. Adding PET decreased the MR values of the C&D waste materials, whilst CB showed higher MR values than RCA. PET blends with CB showed high flexural modulus and fatigue life than PET blends with RCA. The cement-stabilized blends of 5% PET with RCA and CB were found to have physical and strength properties which comply with road authority requirements for pavement base/subbase construction.

Physical and Mechanical Properties of Wood-Plastic Composites Made with Microfibrillar Blends of LDPE, HDPE and PET

The effect of microfibrillar blends of recycled plastics on selected physical and mechanical characteristics of wood-plastic composites (WPCs) was investigated in this study. The production of wood plastic composites was carried out through a two-step extrusion technique. The plastic blends were drawn after extrusion to obtain microfibrillar morphology. The addition of polyethylene-co-glycidyl methacrylate (E-GMA) enhanced compatibility between the two phases and a homogenous structure was seen in the fracture surfaces by scanning electron microscopy (SEM). The crystallinity of base polymers increased with the addition of polyethylene terephthalate (PET) microfibrils, E-GMA and wood flour. The X-ray diffraction (XRD) patterns were also used to determine the crystallinity of all samples. According to the XRD results, the crystallinity degree of recycled plastics was higher than that of virgin plastics. E-GMA improved the water resistance of wood-plastic composites. The mechanical properties of samples were improved with the addition of PET microfibrils. The microfibrillar blending technique was found to be an effective approach for the production of high quality WPCs from recycled plastic blends.

Utilizing recycled PET blends with demolition wastes as construction materials

The rapid growth in plastic and demolition wastes generation by municipal and commercial industries is a significant challenge to developed and developing countries. The substitution of traditional construction materials with recycled materials is a sustainable solution which mitigates landfilling concerns and reduces the need for virgin quarry materials. In this research, an evaluation of the geotechnical and geo-environmental properties of Polyethylene terephthalate (PET) plastic waste and its blends, with two major constituents of construction and demolition (C&D) waste materials was undertaken. Recycled concrete aggregate (RCA) and crushed brick (CB) were blended with 3% and 5% of PET, and the geotechnical properties of six PET blends were evaluated in the laboratory. The experimental programme included particle size distribution, particle density, sieve analysis, flakiness index, Los Angeles abrasion, water absorption, modified Proctor compaction, hydraulic conductivity, and California bearing ratio (CBR) tests. In addition, the response of the PET blends under repeated dynamic loading conditions was investigated using repeated load triaxial (RLT) tests. CBR results of all six PET blends were higher than the minimum CBR requirements for usage as a subbase material. The RLT testing results indicated that PET blends with RCA and CB performed satisfactorily at 98% maximum dry density and at their optimum moisture contents under modified Proctor compaction effort. Furthermore, a geo-environmental evaluation of the PET blends was undertaken which consisted of determination of organic matter content, pH value, total/leachate concentration of the recycled materials for a range of contaminant constituents and the results were compared with requirements specified by environmental authorities. Control samples, 3% and 5% PET blends with RCA and CB satisfied the CBR requirements. Similarly, control samples, 3% and 5% PET blends with RCA were found to be satisfactory for RLT requirements for subbase applications.

Glycidyl methacrylate-based copolymers as new compatibilizers for polypropylene/ polyethylene terephthalate blends

The improvement of flexural properties of polypropylene (PP) could be achieved by blending it with a stiffer polymer like poly(ethylene terephthalate) (PET). The main problem is the compatibilization between a saturated, apolar structure with a polar polyester. Copolymers of glycidyl methacrylate (GMA) and 2-ethylhexyl acrylate (EHA) were prepared, characterized and used as compatibilizers in PP/PET (70/30 wt%) blends at different feed ratios. The effects of compatibilization of these polymers were analyzed by SEM, which shows reduction of the size of PET granules, and by TGA, with an increase in the thermal stability of the compatibilized blends. Thermal properties corresponding to melting and crystallization events were also changed by the introduction of the compatibilizers. The DMTA shows that the Tg of the PET domain is affected by compatibilization, contrary to the Tg of PP domain. The compatibilization efficiency was further confirmed by an increase in flexural strain at flexural strength (eFM).

Experimental and Performance Analyses on Elastomer-Strengthened Polyethylene Terephthalate/Glass Fiber Blends

Ethylene–methacrylate–glycidyl (EMG) copolymer is employed to strengthen polyethylene terephthalate (PET)/glass fiber (GF) blends. This paper starts from investigating the effects of various EMG contents on mechanical properties, thermal properties and fractured surface morphology of PET/GF blends. All of the above-mentioned properties own extreme limits of EMG concentration. The crystallization ability of the blends increases with an increment in EMG content, whereas the crystallinity keeps stable at a relatively high level of 0–20 wt.% EMG loading. The tension, bending and impact properties of PET blends are enhanced with the addition of a self-made three-dimensional hierarchical porous carbon sponge (3DC) based on an optimal additive amount. Results indicate that EMG possesses the capabilities of increasing the toughness of PET/GF blends remarkably and transforming the blends from brittle fracture to tough fracture. According to the results, the blends exhibit the best overall properties as the content of EMG reaches 10–15 wt.%.

Recycled polypropylene blends as novel 3D printing materials

Consumer-grade plastics can be considered a low-cost and sustainable feedstock for fused filament fabrication (FFF) additive manufacturing processes. Such materials are excellent candidates for distributed manufacturing, in which parts are printed from local materials at the point of need. Most plastic waste streams contain a mixture of polymers, such as water bottles and caps comprised of polyethylene terephthalate (PET) and polypropylene (PP), and complete separation is rarely implemented. In this work, blends of waste PET, PP and polystyrene (PS) were processed into filaments for 3D printing. The effect of blend composition and styrene ethylene butylene styrene (SEBS) compatibilizer on the resulting mechanical and thermal properties were probed. Recycled PET had the highest tensile strength at 35 ± 8 MPa. Blends of PP/PET compatibilized with SEBS and maleic anhydride functionalized SEBS had tensile strengths of 23 ± 1 MPa and 24 ± 1 MPa, respectively. The non-compatibilized PP/PS blend had a tensile strength of 22 ± 1 MPa. PP/PS blends exhibited reduced tensile strength to ca. 19 ± 1–3 MPa with the addition of SEBS. Elongation to failure was generally improved for the blended materials compared to neat recycled PET and PS. The glass transition was shifted to higher temperatures for all of the blends except the 50–50 wt. % PP/PET blend. Crystallinity was decreased for the blends, but was highest in the 75–25 wt. % PP/PS and the 50-50 wt. % PP/PET blend with SEBS-maleic anhydride. Solvent extraction of the dispersed phase revealed polypropylene was the matrix phase in both the 50–50 wt. % PP/PET and PP/PS blends.

Thermal and curl properties of PET/PP blend fibres compatibilized with EAG ternary copolymer

Blends of polyethylene terephthalate (PET)/polypropylene (PP) and the ternary copolymer ethylene–acrylic ester–glycidyl methacrylate (EAG) as the compatibilizer were prepared using a twin-screw extruder. The thermal properties, densities and morphologies of the blends were determined using various techniques. Next, PET/PP blend fibres were prepared using a melt–spinning system, and their curl properties were investigated. Scanning electron microscopy (SEM) results showed that the number of PP particles in the PET matrix and size of the PP phase decreased as the EAG content increased. The melting temperature \((T_{\mathrm{m}})\) and cooling crystallization \((T_{\mathrm{cc}})\) values of PP in the PET/PP blends decreased significantly after the addition of 1% EAG. The density of the PET/PP blend fibres decreased significantly with increase in the EAG and PP contents. After curl formation, the curl length of PP in the fibres was shorter than that of PET.