Post-consumer Recycling Research Articles

Performance of Asphalt Mixes Containing Postconsumer Recycled Plastic using Balanced Mix Design Approach and Dry Process

In recent years, use of postconsumer recycled (PCR) plastics in asphalt mixes has been gaining popularity owing to increased environmental awareness, and the need to promote sustainability and conserve natural resources. When using the dry process, incorporation of PCR plastic in asphalt mixes poses several challenges, including mixing, sample preparation, and testing. Use of balanced mix design (BMD) for asphalt mixes containing PCR plastic poses additional challenges that have not been adequately covered in previous studies. To this end, changes in the volumetric properties and performance of PCR plastic-modified asphalt mixes were investigated in this study. For this purpose, an asphalt mix having a nominal maximum aggregate size (NMAS) of 9.5 mm and PG 64-22 binder was designed using the BMD approach. Three different percentages (0.25%, 0.5%, and 1% by weight of aggregate) and two different PCR plastics, namely low-density polyethylene (LDPE) and linear low-density polyethylene (LLDPE) were incorporated in the mix using the dry process. Volumetric properties, namely maximum theoretical specific gravity, bulk specific gravity, voids in mineral aggregate, voids filled with asphalt, air void contents, and densities were determined for both control- (0% plastic) and modified mixes. Also, indirect tensile strength, indirect tensile asphalt cracking test, and Hamburg Wheel Tracking tests were performed to assess the performance of these mixes. A comparison of performance for both plastic type and amount and issues related to the incorporation of PCR plastic using the dry process are discussed in this paper.

Influence of Ethylene-1-Alkene Copolymers Microstructure on Thermo-Rheological Behavior of Model Blends for Enhanced Recycling

Polyethylenes (PE) are the most commonly occurring ingredients for post-consumer recyclates (PCR). The structure–property relationships of different types of model PE-based blends are established using multiple thermo-rheological analyses. Although considered “simple”, the complex behavior of model PE-based blends is experimentally demonstrated for the first time for metallocene-catalyzed, linear, low-density polyethylenes (mLLDPE) with different microstructures that are commonly encountered in PCR. During non-isothermal crystallization, the microstructure of mLLDPE predominantly influences the interaction between mLLDPE and LDPE. Based on the mLLDPE microstructure, the molten LDPE phase acts either as a nucleating agent or as a crystallization rate promoting agent. Both rheological and thermal analyses show that higher activation energy is required for the reptation or movement of polymer chains in a highly branched microstructure with long chain branching (LCB) compared to a linear microstructure with short chain branching (SCB). The quasi-melt response, as measured by thermal analysis under non-isothermal conditions, is distinctly different and sensitive to both the SCB and LCB present in the LLDPE/LDPE blends.

Short- and Long-Term Performance of Pipe Compounds Containing Polyethylene Post-Consumer Recyclates from Packaging Waste.

The polymer industry is pushed to present solutions that lead to a circular plastics economy. High plastic packaging waste recycling targets will eventually lead to a high availability of packaging material recyclates. Although the use of polyethylene terephthalate (PET) recyclates is prescribed by regulations to be used in new PET bottles, no such regulation prescribes the use of polyethylene recyclate (rPE) in new products. One possibility of using rPE, which is considered by the European Union, is the use within pipe materials. Pipe applications demand a certain property profile, most prominently a high slow crack growth (SCG) resistance, which is not met by most packaging materials or recyclates made from it. Hence, this work investigates the use of commercially available post-consumer recyclates out of high-density polyethylene from packaging applications in compounds together with high SCG-resistant virgin PE pipe material with a PE100-RC specification. Two rPEs were acquired from German producers and blended to compounds consisting of 25 m%, 50 m% and 75 m% recyclate. These compounds, together with the pure recyclates and several virgin pipe materials acting as benchmarks were tested in terms of short- and long-term mechanical performance and with other basic characterization methods. Several compounds exceeded the performance of one tested virgin PE pipe material, an injection molding PE80 grade, in several categories. The content of recyclate needed to outperform this benchmark grade was mostly dependent on the resulting melt flow rate (MFR) of the compound and thus also of the MFR of the pure recyclate. Furthermore, different levels of polypropylene contaminations within the recyclates resulted in differently contaminated compounds. This is proved to influence the SCG resistance too, as compounds of similar MFRs but with different SCG resistances were found.

Recycle Ability of Post-Consumer Recycled Plastic (PCR) from the Chlorine Tank

Plastic waste that used in our daily life is a major problem of environmental contaminate because it produces microplastics after degradation resulting in the harmful of living organisms, including humans. Therefore, this research has an idea to solve this problem by recycling the plastic waste. High density polyethylene (HDPE) plastic waste from the chlorine tank in fishing industry is considered. This work was designed to blend it with virgin HDPE plastic pellets. The ratio of blended plastics between virgin HDPE pellets and HDPE plastic waste from the chlorine tank which was defined as post-consumer recycled plastic (PCR) was 100:0, 50:50, 40:60, 30:70, 20:80 and 0:100 wt%, respectively. The result shows unchanged thermal properties of plastic blends caused by the same type of polymer, thus the PCR without blending with the virgin HDPE plastic is selected for recycle ability studies. The PCR was rerun in the twin screw extruder in the range of 0 - 80 extruded recycle time to observe the thermal, rheological, mechanical, and physical properties. It was found from our result that 20 recycling time of PCR was appropriate for maximum recycling process due to slightly change rheological characteristics, mechanical properties as well as product’s color.
 HIGHLIGHTS
 
 Thermal properties of post-consumer recycled plastic (PCR) after recycling and its blending with virgin HDPE
 Rheological change of post-consumer recycled plastic (PCR) after recycling
 Mechanical and physical properties of post-consumer recycled plastic (PCR) after recycling to meet a customer need
 
 GRAPHICAL ABSTRACT

Demonstration Project for Ground Tire Rubber and Post-Consumer Recycled Plastic-Modified Asphalt Mixtures

Research has demonstrated that asphalt pavements can be a strategic destination for some of the major streams of waste materials around the globe, such as scrap tires and plastics. Ground tire rubber (GTR) from scrap tires has been used in asphalt pavements since the 1960s but has yet to approach its full potential in relation to market adoption. The heightened restrictions imposed by China in relation to waste stream contamination in 2018 have catalyzed research on incorporating post-consumer recycled (PCR) plastics into asphalt pavements. A field demonstration project was carried out in Columbia, MO to evaluate modern recycled plastic and GTR additives in an asphalt pavement overlay. The demonstration focused on dry-process modification, which requires minimal alterations to an existing asphalt plant and allows a higher amount of recyclates to be utilized. The project was also designed to assist in the Missouri Department of Transportation’s early roll-out of balanced mix design asphalt design and quality assurance specifications. The results of the study indicated the viability of dry-process GTR and PCR plastic additives used with neat (unmodified) asphalt binder as an alternative to binders modified with virgin polymers, chemical treatments, or both, in a wet process. The results of the study also suggest the viability of hybrid wet polymer-modified binder with dry-process PCR plastic as a greener alternative to binders modified with virgin polymers, chemical treatments, or both. Future studies will be needed to examine additional PCR plastic streams, especially mixed polymer streams.

Recycling technologies for enabling sustainability transitions of the fashion industry: status quo and avenues for increasing post-consumer waste recycling

A major environmental issue of the rise in garment production is a steep increase of textile waste. At the same time, recycling technologies appear to be promising avenues for sustainability transitions of the fashion industry. This article examines the chances and challenges of scaling recycling technologies for textiles and considers the collection and sorting processes as well as the actual reuse. Drawing on case studies and expert interviews, the results indicate current obstacles and opportunities for accelerating diffusion of recycling technologies. Various initiatives are promising, however industry structures, garment designs, and business models need to be re-orientated and re-aligned to accelerate these recycling concepts. Applying the greenwashing notion that acknowledges co-creation by producers and consumers, the article critically argues that the focus on recycled polyester bottles for garments distorts incentives to improve other recycling technologies and masks the true cost of textile-waste recycling. Instead, fashion-brand companies and retailers should leverage their market power to foster sustainability standards in the global recycling industry.

Recycling of Post-Consumer Packaging Materials into New Food Packaging Applications—Critical Review of the European Approach and Future Perspectives

The European strategy for plastics, as part of the EU’s circular economy action plan, should support the reduction in plastic waste. One key element in this action plan is the improvement of the economics and quality of recycled plastics. In addition, an important goal is that by 2030, all plastics packaging placed on the EU market must either be reusable or can be recycled in a cost-effective manner. This means that, at the end, a closed-loop recycling of food packaging materials should be established. However, the use of recyclates must not result in less severe preventive consumer protection of food packaging materials. This may lead to a conservative evaluation of authorities on post-consumer recyclates in food packaging applications. On the other hand, over-conservatism might over-protect the consumer and generate insurmountable barriers to the application of post-consumer recyclates for food packaging and, hence, counteract the targets of circular economy. The objective of this review is to provide an insight into the evaluation of post-consumer recyclates applied in direct contact to food. Safety assessment criteria as developed by the European Food Safety Authority EFSA will be presented, explained, and critically discussed.

Implementation of circularity indicators in a household product manufacturing company

Measuring circularity is a hot topic and has gained a lot of attention among policy makers, companies and academia. Such indicators are often applied to assess the implementation level of more circular supply chains. Although life cycle assessment (LCA) will remain important to ensure our industrial activities contribute to an economic system with an overall lower environmental burden, existing characterization methods for the use of abiotic resources have been heavily debated and criticized by the scientific community and by industry. Due to these limitations in current LCA methods, circularity metrics are useful to evaluate the performance of systems in terms of resource effectiveness. BSH Hausgeräte GmbH (BSH) is the largest manufacturer of home appliances in Europe and one of the leading companies in the sector worldwide. BSH is seeking a new Key Performance Indicator (KPI) to measure their progress in implementing circular strategies such as product service system and improving post-consumer material recycling. This KPI will be used in combination with other indicators already monitored by BSH such as the environmental impact of their products using LCA. In this paper, the suitability of the Product Circularity Indicator (PCI) developed by the KU Leuven as a KPI for circularity within a manufacturing company of household products is investigated. The PCI is a novel circularity indicator that aims to measure the circularity of product at micro-level. Based on the baseline results, the main hotspots that contribute to a low PCI are identified. A sensitivity analysis allows to better understand the potential of specific system parameters to improve the circularity performance of the assessed products and services. The PCI has proven to be suitable for application in an industrial company because it captures all relevant factors influencing the circularity of a product.

Regulating Markets for Post-Consumer Recycling Plastics: Experiences from Germany's Dual System

Regulating Markets for Post-Consumer Recycling Plastics: Experiences from Germany's Dual System

Evaluation of tensile and flexural strength properties of virgin and recycled high-density polyethylene (HDPE) for pipe fitting application

Innovative ways of eliminating heavy plastic waste all over the world must be designed and implemented via recycling of post used plastic materials by making new products. As a result of continuous use of plastic materials, adverse effect on the environment and economic issues had been a problem confronting the post-consumer recycling of these materials. High-Density Polyethylene (HDPE) polymers are widely being used and its products are preferable than metals having the properties such as lightweight, ease of manufacture, stronger and tough.This research work focuses on investigating the flexural and tensile strength properties of virgin and recycled HDPE for pipe fitting application. The mixing of recycled with virgin HDPE were done at different weight percentages (0:100, 10:90, 20:80, 30:70, 40:60, 50:50, 60:40, 70:30, 80:20, 90:10, and 100:0). Eleven (11) T-reducer pipe fitting samples were produced via injection moulding machine. Data of flexural strength test for selective samples similar with tensile test in showed that 100 wt% virgin HDPE had 39.98 MPa whereas 100 wt% recycled HDPE had 20.88 MPa. Generally, all the mechanical (tensile and flexural) properties decreased as number of recycled contents increased. Because, recycled high density polyethylene scrap (rHDPE) have weaker bond strength than virgin high density polyethylene (vHDPE) materials. Bond strength is very strong in virgin HDPE, and they also have molecular weight that is large. Also, there is highest rigidity in virgin HDPE. Rigidity is very high in virgin HDPE due to high toughness. So, with lower load, bond strength is not allowed to break. But there is weaker bond strength in 100% recycled scraps of HDPE as a result of different kinds of stresses they have been subjected to during prior usage.

Influence of Recyclates on Mechanical Properties and Lifetime Performance of Polypropylene Materials

In Europe, the amount of plastic waste which was recycled and further processed into new products was only about 13 % in 2020. One option to process higher volumes of post-consumer recyclates into new products is blending with virgin materials. In order to investigate the effect of recyclates on rheological and structural material properties, a post-consumer polypropylene recyclate (PP-r) was added to a virgin polypropylene (PP-v) in different contents of 10 %, 25 % and 50 %, respectively. Mechanical and fracture mechanical properties were analysed and compared with initial conditions of the original virgin and recycled materials. In addition, the influence of two different recyclates (PP-r) was examined by using grades of a high (PP-r1) and low (PP-r2) melt flow rate (MRF). Results demonstrate that the blending of virgin material with recyclates had a clear influence on material properties. The MFR values increased with higher recyclate content. Tensile tests showed a reduction of the Young's modulus and the yield strength with increasing recycling content. While tensile test properties were significantly affected by a recycling content over 10 %, notched Charpy Impact strength started to change above 25 % and 50 % of PP-r1 and PP-r2, respectively. The resistance against slow crack growth (SCG) of the materials was analysed by the crack round bar (CRB) test. Results indicate that a small recyclate amount of 10 % does not significantly reduce the SCG resistance of the blend compared to the virgin material. However, the SCG resistance decreases dramatically with higher recyclate content.

Modelling of the Motion and Interaction of a Droplet of an Inkjet Printing Process with Physically Treated Polymers Substrates

This study examines the effect of energetic surface treatment on the adhesion strength of high-density polyethylene (HDPE), polypropylene (PP) and polyethylene terephthalate (PET) substrates. The purpose of this work is to determine the surface wettability of polymers suitable for food contact. These plastics have been treated with various pre-treatment methods to improve surface tension and good adhesion for inkjet printing and avoid any visual changes. It is important to determine the adhesion of the ink to the polymer surface to improve post-consumer recycling. Digital inks have been tested on various treated plastics to analyse coating properties and adhesion forces in accordance with DIN ISO 2409 standards. The impact of the inkjet droplet on the treated and non-treated surface was also investigated using the COMSOL computer simulation software.

Safety Evaluation of Polyethylene Terephthalate Chemical Recycling Processes

Polyethylene terephthalate (PET) is one of the main packaging materials for beverage bottles. Even if this polymer is good to recycle, mechanical recycling processes need a well-sorted input fraction. For less-sorted PET packaging, or even non-food input sources, chemical recycling seems to be a solution to increase PET recycling. For post-consumer recyclates in packaging applications, it is essential that the safety of the recyclates is guaranteed, and the consumers’ health protected. For mechanical recycling processes, evaluation criteria are already established. For chemical recycling processes, however, such evaluation criteria are only roughly available. This study evaluated the safety of the chemical recycling process similar to the approach of the European Food Safety Authority (EFSA). However, due to the lack of information about the contamination level of the input materials for the chemical recycling process, the evaluation was adapted. In addition, the evaluation should be performed separately for the depolymerisation and for the repolymerisation steps. However, due to the high cleaning efficiencies of both steps, the evaluation can focus on the repolymerisation. This simplifies the assessment of the chemical recycling processes considerably.

Characterization of Composition and Structure–Property Relationships of Commercial Post-Consumer Polyethylene and Polypropylene Recyclates

The current efforts in moving closer towards a circular plastics economy puts massive pressure on recycled plastics, especially recycled polyethylene (rPE) and recycled polypropylene (rPP) to enter new markets. Their market penetration remained low so far, despite PE and PP constituting the largest share of plastic wastes. However, with the current imperative of more circularity comes a new focus on performance of recyclates. Hence, a detailed understanding of composition and structure–property relationships of post-consumer recyclates has to be developed. Five recycling companies from the Austrian and German markets were asked to supply their purest high-quality rPE and rPP grades. These were characterized by differential scanning calorimetry (DSC), thermo-gravimetric analysis (TGA), and Fourier-transform infrared (FTIR) spectroscopy, and micro-imaging. Technological characterization included density measurements, determination of the melt flow rate (MFR), and Charpy impact testing. All recyclates contained diverse contaminants and inclusions ranging from legacy fillers like calcium carbonate to polymeric contaminants like polyamides or polyolefin cross-contamination. The overall amount, size, and distribution of contaminants varied significantly among suppliers. Furthermore, first structure–property relationships for polyolefin recyclates that link inorganic content and polymeric purity with density and impact performance could be derived.

Thermo-mechanical variability of post-industrial and post-consumer recyclate PC-ABS

The aim of this work is to investigate the performance variability of post-industrial (PIR) and post-consumer recycled (PCR) polycarbonate acrylonitrile-butadiene-styrene (PC-ABS). In addition, necessary testing methodology for understanding polymer variation in recycled polymers are established. The thermal expansion behaviour of all tested material were found to be similar and FT-IR testing revealed no conclusive evidence of oxidative degradation. Both PIR and PCR exhibited similar levels of variation in mechanical properties compared with prime samples, with the exception of elongation at break and quasi-static impact behaviour. In these two tests, prime polymers showed lower variation and superior performance to both recycled polymers. The presence of defects and changes in molecular weight were determined to be leading causes of the reduced deformability. Our work contributes by identifying key areas where recycled PC-ABS show good potential as replacements for neat PC-ABS. Furthermore, the work demonstrates methods for material testing against performance criteria to pave way for effective replacement of neat PC-ABS with its recycled counterparts.

Borealis and TOMRA open state- of-the-art plant for post-consumer plastic waste sorting and advanced mechanical recycling.

Borealis and TOMRA open state- of-the-art plant for post-consumer plastic waste sorting and advanced mechanical recycling.

Learnings about design from recycling by using post-consumer polypropylene as a core layer in a co-injection molded sandwich structure product

In pursuit of a circular economy of plastics, there is a need to use more recycled plastics for new products. Polypropylene (PP) constitutes a major fraction of post-consumer plastic wastes, and mechanical recycling is currently the most sustainable recovery strategy. Sandwich-structured multi-layer products with recyclate cores are a seemingly easy way to satisfy demands for recyclate utilization without compromising on product aesthetics. We present the case of a reusable plastic transport box with a recycled content of 45 wt% manufactured by a co-injection molding process. The box was characterized by spectroscopic and thermo-analytical methods. Mechanical performance was tested on both specimen and product levels. A comparison was made to transport boxes fabricated entirely from virgin or entirely from recycled PP, respectively. A number of contaminants including foreign polymers were identified within the recyclate core layer of the sandwich-structured material. While these contaminants had no deteriorative effect on stiffness-controlled performance, a strong influence on strength-controlled and impact-related properties was observed. We argue that the presence of inclusions of both polymeric and inorganic nature is an intrinsic quality characteristic of post-consumer recyclates. These need to be considered in any design-from-recycling philosophy to guarantee functionality, reliability, and safety of products with recycled content.

AN OVERVIEW OF PLASTIC WASTE RECYCLING IN THE URBAN AREAS OF JAVA ISLAND IN INDONESIA

Plastic products have been an integral part of human lives. However, concerns over plastic pollution have been growing. Thus, alternative practices that allow more sustainable production and consumption pattern are urgently needed. Improving plastic recycling management is one of the solutions to prevent an increase in plastic pollution. This paper aims to uncover the potential of plastic recycling, to define factors that can leverage the expansion of the recycling process, and to evaluate possible measures that can realize such expansion, especially given the limited literature on these topics. Therefore, a four-month study, which involved two months of rigorous primary survey and interview and secondary data collection process to obtain valuable and accountable raw data, was conducted between October 2019–January 2020. The conducted study showed that the urban population in Java Island generated around 189,349 t of plastic waste per month, but only 11.83% of it was collected. The remaining 88.17% was either directly transported to landfills or littered in the environment. Five major plastic types were collected in the recycling stream, namely, rigid PP (25%), film HDPE (20%), rigid PET (20%), rigid HDPE (14%), and film PP (9%) with more than 80% of collected plastic waste originating from waste pickers. The paper highlights the major challenges in improving post-consumer recycling: (i) failure of post-consumer plastic recyclable to meet the quality industrial standard; (ii) limited recycling processes and infrastructure; (iii) low market demand for recycled products.

Material flow analysis and sustainability of the Italian plastic packaging management

The plastic management, specifically plastic packaging management, represents one of the main sectors responsible for environmental and health impacts. The European Commission, in 2018, released a Strategy for Plastics in a Circular Economy and a new Packaging Waste Directive for closing the loop of this management system, forcing member states to recycle 55% of plastic packaging by 2030. The level of circular economy in a supply chain can be measured with material flow analysis, a useful tool to help policy makers forecast the recycling capability and to provide suggestions for improving the plastic packaging management sustainability. Considering the gap in literature in this field, the principal aim of this paper is to apply material flow analysis to measure the level of circular economy in the 2017 Italian plastic packaging management, by using the software STAN 2.6. Particularly, it assessed its post-consumer recycling rate, according to the new calculation method established by the Waste Directive. Secondly, this result is compared with that of the other EU-28 countries. The findings indicate that Italy has a good recycling rate, almost 44%, and that the energy recovery and landfill levels are about 40% and nearly 17%, respectively. There is room for making plastic waste management more efficient. Some of the EU-28 countries have wide margins of improvement thanks to large amounts of plastic packaging in landfills, whereas others, although they present good recycling rates, could tackle some problems in adopting the circular economy approach because they continue to burn plastic packaging in waste-to-energy plants.

Exploring Odor Minimization in Post-Consumer Plastic Packaging Waste through the Use of Probiotic Bacteria

Plastic packaging represents a large proportion of the plastic consumption throughout the world. The negative environmental impact associated with plastic packaging waste can be in part abated by recycling plastics, and increasing numbers of regulatory frameworks are being adopted towards this goal. Despite recent advances in modern recycling technologies, the production of high-quality polyolefin recyclates remains a challenge. Among other functional requirements, odor plays a crucial role in the acceptance of recycled packaging. This presents a challenge, as odor contamination in plastic packaging waste can stem from diverse sources, such as spoilage processes, and strongly depends on the quality of the post-consumer input material. The present study addressed this issue by exploring potential odor abatement of malodors in packaging waste through the use of probiotic bacteria. Specifically, probiotics were added to a mixed post-consumer plastic packaging waste fraction, which was subsequently evaluated using human sensory and gas chromatography–olfactometric analyses. A comparison of treated with untreated plastic waste fractions revealed significant sensory differences. Further structural elucidation of the causative odorants confirmed a reduction in malodorous microbial metabolites, although complete odor removal was not achieved. However, this environmentally friendly approach may represent an essential step towards overcoming the odor burden in post-consumer plastic packaging recyclates.