Polymer matrix composites have established themselves in the materials family due to their improved properties like high specific stiffness and strength, durability etc. Recycled polyethylene ...terephthalate (RPET) is being used as matrix material in a variety of polymer matrix composites. Composite materials based on RPET matrix, in addition to being cost effective, are also environment friendly. Use of RPET as matrix material not only reduces the consumption of virgin materials, but it also simultaneously addresses the concern regarding environmental pollution due to post consumer PET waste. This review compiles and critically analyses the efforts of various researchers regarding the influence of; different types of reinforcing materials such as synthetic and natural fibers, micro and nano fillers, blending of RPET with various virgin polymers, on the properties of composite materials based on RPET.
The integration of various polymers in bitumen is common practice to reduce its thermal susceptibility. Nowadays, recycled materials are re-purposed in roads to improve the overall pavement ...performance and durability. Specifically, the use of soft plastics has been increasingly looked after by local governments and road authorities to possibly limit landfill, hence helping with the waste management issues experienced by many countries. This study evaluates the use of a very common and largely available soft plastic - recycled linear low-density polyethylene (R-LLDPE) - for modification of bitumen. To assess its applicability in the road sector, the base bitumen and R-LLDPE modified bitumen blends were compared through physical, chemical, rheological and thermal evaluation. It was observed that due the addition of high concentrations of R-LLDPE the viscosity and softening point were increased from 0.62 Pa s and 44.1 °C up to 5.75 Pa s and 122.3 °C, respectively, whereas the penetration value decreased from 59.3 to 14.3 (0.1 mm). A progressive increase in viscosity with increasing concentration of R-LLDPE indicates substantial reduction in workability due to the greater polymer-dominant phase. An increase in the intensities of peaks and the absence of new peaks during Fourier transform infra-red (FTIR) analysis confirms the successful blending of the recycled polymer into the bitumen matrix. The thermogravimetric analysis (TGA) shows that the modified bitumen had less evaporation and higher thermal stability than base bitumen. The rheological evaluation highlighted how the R-LLDPE addition significantly affected the thermo-susceptibility of the bitumen and improved the resistance to permanent deformation at high temperature and elastic recovery. Based on the overall findings of this study, it can be stated that R-LLDPE – if dosed correctly and sourced from homogeneous sources – can enhance the overall bitumen performance without significant drawbacks. In particular, 3% R-LLDPE is considered a suitable modification for most environmental conditions, whereas 6% R-LLDPE is only ideal for tropical climates. Higher dosage is not recommended.
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•Soft plastics (L-LDPE) was recycled and blended with bitumen providing betterments.•Up to 3% of recycled soft plastics was deemed suitable for bitumen modification.•More than 6% recycled soft plastics greatly affected bitumen viscosity.•Improved resistance to rutting (MSCR test) was identified with increased plastics.•Controlled sources of waste plastics proved to be suitable to modify bitumen.
A nanofibrous membrane made of unmodified recycled polyethylene terephthalate (rPET) was fabricated by electrospinning using plastic water bottle as raw materials. Using rPET polymer to fabricate ...membranes may help limit the discharge of plastic bottle waste into the environment and can treat oily wastewater simultaneously, especially emulsions. The variation in the concentration of rPET polymer and the properties of electrospun nanofibers, such as surface morphology and fiber diameter, had a significant impact on both the efficiency of oil droplet capturing and the surface wettability of the membrane. Water-in-oil emulsions and oil-in-water emulsions were separated using the nanofibrous membranes of different concentrations of rPET polymer, and the separation efficiencies at different concentrations of oil, and oil types were measured. The rPET nanofibrous membrane exhibited a water contact angle of 140.1° and was superoleophilic in air and underwater. The membranes exhibited excellent separation performances: >98% separation efficiency and a flux of more than 6500 L m-2 h-1 for water in hexadecane and octane emulsions; >95 % efficiency and a flux of 1509.70 L m-2 h-1 after three separation cycles of water-in-oil emulsions. For oil-in-water emulsions, the separation efficiencies were higher than 95 %, and flux was more than 3525.22 L m-2 h-1 for hexadecane octane and heptane in water emulsions, with an efficiency of >87.9 % and flux of 4186.20 L m-2 h-1 after three separation cycles. Moreover, the as-prepared membrane exhibited high performance of oil-water separation in harsh conditions, including strong acidic, strong basic, and strong salt solutions, with separation efficiencies of more than 98 % and flux of more than 12,700 L m-2 h-1. However, as water accumulated on the membrane surface, absorption and separation efficiency and flux were lowered significantly. This suggests the need to enhance the efficiency of the membrane and reduce the chance of water accumulation on the membrane surface.
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AbstractThis paper presents a pilot study on the characterization of the physical and mechanical properties of a novel green concrete with two different substituted recycled plastic aggregates. A ...reference mix with an average compressive strength of around 60 MPa is considered. Recycled polyethylene terephthalate (PET) powder and recycled mixed plastic polypropylene (PP) and polyethylene (PE) granules were adopted to substitute fine and coarse aggregates. Two different substitution strategies were employed. In the first one, the PET powder is used to substitute the fine sand by volume. In the second one, the PET powder is used to substitute the fine sand while the recycled mixed plastic granules are used to substitute the coarse sand and fine coarse aggregates by volume (50% for PET powder and 50% for recycled mixed plastic granules). Four total replacement levels (5%, 10%, 20%, and 30%) by volume were considered. The fresh concrete properties (slump and density), compressive and flexural behavior, toughness, and permeability are investigated. Finally, a microscale characterization of the plastic-paste interface is provided. An interpretation of the test results of this study by comparing them with the findings of previous studies is provided, along with the provision of two predictive equations for the compressive and flexural strength reduction factors. Results show reduced flowability for PET cases due to particle shape, slight compressive strength reduction at low substitutions, improved flexural strength at low levels, decreased permeability, and microscale enhancements. The comprehensive evaluation indicates promising physical and mechanical performance of the novel green concrete.
•Recycled Plastic Waste (RPW) improved virgin (VA) & sulfur extended asphalt (SEA).•RPW made VA&SEA stiffer/elastic thus better resistance to rutting/fatigue cracking.•Addition of RPW to VA&SEA ...slowed the oxidation reactions of the binder.•Addition of RPW to VA&SEA made binder more suitable for wider range of temperature.•The modification effect of RPW on asphalt included chemical and physical processes.
This study examines the effect of two different recycled plastic waste (RPW) which are high and low-density polyethylene (RHDPE and RLDPE) on the rheological/viscoelastic characteristics and aging performance of virgin asphalt and sulfur extended asphalt (SEA). Four dosages of the RPW additives representing 2%, 4%, 6%, and 8% by weight of the asphalt binder were investigated. The rheological characteristics of the RPW modified binders (virgin and SEA) are characterized at original and short-term aging conditions through the Rotational Viscometer (RV) and dynamic shear rheometer (DSR) tests. Fatigue performance is also characterized at the long-term aging condition. Also, high-temperature performance, dynamic storage stability (DSS), multiple stress creep and recovery (MSCR) are studied. Testing results show that RPWs lead to improved rutting and fatigue performance. Adding RPW to the virgin and SEA binders slows the binder oxidation reactions during the short-term aging. The Aging Index (AI) is found to be dependent on the asphalt rheological properties, amount/type of RPW, binder type, and temperature. RHDPE leads to an unstable modified virgin asphalt. Less than 4% RHDPE or 8% RLDPE with virgin asphalt show good DSS in terms of degradation and separation. The RPW with SEA meets the requirement of time degradation and separation set by the Federal Highway Administration (FHWA). The temperature susceptibility of asphalt binder decreases dramatically with the RPW modification making the asphalt binder more suitable for use at a wider range of temperatures.
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•Samples of graphene/RPE–modified asphalt were prepared and the effects of graphene on the storage stability, deformation resistance, elasticity, fatigue resistance and rutting ...resistance of RPE–modified asphalt were evaluated.•The correctness of the asphalt model was verified by using indexes of the density, glass transition temperature (Tg), radial distribution function (RDF), four–component content, and solubility parameters.•The intermolecular interactions were evaluated using the concentration distribution, binding energy, diffusion coefficient, and system equilibrium state structure, and the effect of graphene on RPE in molecular interactions was analyzed.
The use of recycled polyethylene (RPE)-modified asphalt not only allows for significant consumption of waste plastics, but also enhances the performance of the asphalt matrix. However, storage stability is a major challenge for RPE-modified asphalt. The objective of this study was to investigate the enhancement mechanism of graphene on RPE-modified asphalt using molecular dynamics simulations based on a comprehensive evaluation of the temperature performance, storage performance and rheological properties of graphene/RPE-modified asphalt. The results showed that graphene enhanced the high-temperature rheological properties, medium-temperature fatigue resistance, low-temperature crack resistance and storage stability of RPE-modified asphalt to some extent. However, the self-aggregation phenomenon limits the enhancement effect of graphene, and the optimal laboratory admixture is 0.5 wt%. Molecular dynamics simulations revealed that graphene reduced the binding energy of asphaltenes to non-polar molecules (saturate and aromatic) from 64.28 kcal/mol and 51.39 kcal/mol to 53.12 kcal/mol and 41.73 kcal/mol, respectively, while the binding energy of RPE to non-polar molecules increased from 16.38 kcal/mol and 8.44 kcal/mol to 24.37 kcal/mol and 14.58 kcal/mol, respectively. In addition, graphene elevated the diffusion coefficient of non-polar molecules by about 8% and decreased the diffusion coefficient of polar molecules by about 2%. The concentration distribution results suggest that graphene disrupts the colloidal structure of the asphalt matrix, which may trigger changes in the asphalt properties. The results of molecular simulation adequately explain the enhancement mechanism of graphene, which can provide a reference for the performance enhancement of RPE-modified asphalt.
•The recycled polyethylene granule was proposed as drainage layer in green roof.•The technological solution consisted of a substrate made of local-sourced materials and a micro-drilled plastic.•The ...energy-efficient design was based on the thermo-physical parameters of the green roofs and of the building and on the thermal dynamic parameters.•The proposed green roof solution was proved to be effective in increase green roof thermal performance in Mediterranean climate.
Green roofs were proposed to broaden nature-based solutions within the perspective of the ecological transition for the built environment. In this paper, an innovative and sustainable green roof was designed to optimize the energy performance in Mediterranean area during summer season by means of local-available and recycled materials, thus reducing the environmental impacts. This new green roof technology consisted of recycled polyethylene granules from the regeneration of disused agricultural plastic films as drainage layer and a substrate made of local-sourced materials with high percentage of organic matter and it was compared to two traditional green roofs and to the existing roof. The energy-efficient design was based on the thermo-physical parameters of the green roof (surface temperatures, heat flows and volumetric water content) and of the building (surface temperature of the ceiling) and on the thermal dynamic parameters (decrement factor, time lag and cooling potential). In addition, these thermo-physical parameters were correlated to the Mediterranean climate during summer season. The result demonstrated that although the proposed green roof reached higher surface temperatures than commercial solutions, it maintained an almost constant volumetric water content, it reduced daily fluctuations between minimum and maximum temperatures, it resulted in lower thermal flow through the cross-section, it reduced the surface temperatures inside the building by about 2 °C compared to the traditional roof, thus decreasing the energy consumption for building cooling and greenhouse gas emissions, and it had better dynamic thermal performance than commercial green roofs. Once the energy-efficient design of the proposed green roof technology was proved, the sustainability and the life cycle performance of the recycled polyethylene was discussed, also considering the costs.
•Micronized PET improved asphalt binders’ viscosity and adhesion to aggregates.•Micronized PET improved resistance of mixes to rutting, cracking, and stripping.•Use of micronized PET as an asphalt ...binder additive was found to be feasible.
The limited cost-effective avenues available for recycling Polyethylene Terephthalate (PET), widely used in packing bottled water, has turned it into a global environmental challenge. A number of studies have evaluated use of recycled PET bottles as an aggregate replacement in asphalt mixes. However, their outcomes indicated that performance of mixes did not significantly benefit from strength and high elasticity of PET. This study was undertaken to investigate the effect of incorporating different amounts (0, 5, 10, 15, and 20%) of Micronized PET (MPET) as a modifier in a PG 58-28 asphalt binder on its viscosity and adhesion to different types of aggregates. Also, the effectiveness of using MPET-modified asphalt binder in mixes for improving their resistance to rutting, cracking, and moisture-induced damage was evaluated. For this purpose, binder blends’ dynamic viscosities were measured using a rotational viscometer. Pull-off strength of MPET-modified binders with aggregates (two granite and one quartzite) was determined by conducting binder bond strength tests on dry and moisture-conditioned specimens. Surface Free Energy (SFE) analysis was also carried out to further understand the adhesion, cohesion, and debonding mechanisms. Furthermore, Superpave asphalt mixes containing MPET-modified PG 58-28 asphalt binder blends were prepared in the laboratory and their resistance to cracking, rutting, and moisture-induced damage was evaluated by conducting semi-circular bend, Hamburg wheel tracking, and tensile strength ratio tests. Testing asphalt binders and SFE analysis showed that, incorporation of MPET in asphalt binder significantly improved viscosity and binder-aggregate adhesion as well as their resistance to stripping. Additionally, testing asphalt mixes showed that, an increase in MPET content resulted in an increase in resistance to cracking, rutting, and moisture-induced damage. It was concluded that use of MPET as an asphalt binder modifier is an effective method for improving mechanical properties of asphalt pavements while addressing an environmental concern and preserving natural resources.
Smart Sensors
In article number 2400491, Jiun‐Tai Chen and co‐workers fabricated a dual‐responsive spiropyran‐based smart sensor through a simple layer‐by‐layer assembly process using upcycled ...thermoplastic polyester elastomer materials derived from recycled polyethylene terephthalate. The sensor can be stimulated by UV irradiation or acid vapors, resulting in an apparent color change to purple or yellow, respectively.
For environmental conservation, post-consumer polyethylene terephthalate (PET) bottles are recycled using methods ranging from mechanical recycling to various chemical recycling processes.
In this ...study, the characterization of recycled PETs and PET–nylon6 blend knitted fabrics, and virgin PET knitted fabric, was carried out with the aim of broadening the application of recycled PET fabrics. The tensile strength values of mechanically and chemically recycled PET knitted fabrics were similar to those of virgin PET knitted fabric. The elongation of recycled PET–nylon6 blend knitted fabric was the best. Both virgin and recycled PET knitted fabrics had excellent pilling resistance. Based on the drape ratio, the recycled PET–nylon6 blend knitted fabric was more flexible than other samples. The warm/cool feeling (Qmax), compressional and surface properties were measured using the Kawabata evaluation system for fabrics (KES-FB system). The compressional properties of mechanically recycled PET knitted fabric were similar to those of virgin PET knitted fabric. The recycled PET–nylon6 blend knitted fabric showed the smoothest appearance and coolest feeling among the four samples. Moisture regain and moisture permeability were the best in recycled PET–nylon6 blend knitted fabric. However, the wickability of mechanically recycled PET knitted fabric was better than other recycled PET knitted fabrics.
