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Plastics are versatile materials used in a variety of sectors that have seen a rapid increase in their global production. Millions of tonnes of plastic wastes are generated each year, which puts pressure on plastic waste management methods to prevent their accumulation within the environment. Recycling is an attractive disposal method and aids the...
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... are fully saturated hydrocarbons synthesised by the polymerisation of an olefinic monomer in the presence of a catalyst [127]. The olefinic monomers, ethylene and propylene, depicted in Figure 4, are obtained from the cracking of petroleum feeds or the dehydrogenation of alkanes [126]. Different grades of PP and PE exist, such as blow moulding or injection moulding grades, which differ in melt viscosity and can be obtained through the use of co-monomers such as hexane or butane during olefinic polymerisation [127]. ...
Context 2
... are fully saturated hydrocarbons synthesised by the polymerisation of an olefinic monomer in the presence of a catalyst [127]. The olefinic monomers, ethylene and propylene, depicted in Figure 4, are obtained from the cracking of petroleum feeds or the dehydrogenation of alkanes [126]. Different grades of PP and PE exist, such as blow moulding or injection moulding grades, which differ in melt viscosity and can be obtained through the use of co-monomers such as hexane or butane during olefinic polymerisation [127]. ...
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The awareness for more environmentally sustainable packaging solutions is steadily growing. With both consumers and manufacturers looking to minimize their impacts on the environment, the need for easy-to-implement and standardized measures strengthening a circular economy rises. In the research, the goal was to determine whether the carbon footpri...
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... Plastic waste is a major environmental issue, with only 9% of the world's plastics being recycled [1]. Polyolefins, encompassing polypropylene (PP) and polyethylene (PE), are the main components in municipal waste due to their abundant use in commodity applications as they possess good mechanical properties and processability, in addition to having high availability and low manufacturing costs [2][3][4][5]. The complete separation of PP and PE during mechanical waste recovery is uneconomical due to their close densities and structural similarity; therefore, PP and PE usually remain mixed [6][7][8]. ...
This paper provides evidence and discusses the variability in the thermomechanical behaviour of virgin and recycled polypropylene/high-density polyethylene blends without the addition of other components, which is sparse in the literature. Understanding the performance variability in recycled polymer blends is of critical importance in order to facilitate the re-entering of recycled materials to the consumer market and, thus, contribute towards a circular economy. This is an area that requires further research due to the inhomogeneity of recycled materials. Therefore, the thermal and mechanical properties of virgin and recycled polypropylene/high-density polyethylene blends were investigated systematically. Differential scanning calorimetry concludes that both the recycled and virgin blends are immiscible. Generally, recycled blends have lower overall crystallinity and melting temperatures compared with virgin blends while, remarkably, their crystallisation temperatures are compared favourably. Dynamical mechanical analysis showed little variation in the storage modulus of recycled and virgin blends. However, the alpha and beta relaxation temperatures are lower in recycled blends due to structural deterioration. Deterioration in the thermal and mechanical properties of recycled blends is thought to be caused by the presence of contaminants and structural degradation during reprocessing, resulting in shorter polymeric chains and the formation of imperfect crystallites. The tensile properties of recycled blends are also affected by the recycling process. The Young’s modulus and yield strength of the recycled blends are inferior to those of virgin blends due to the deterioration during the recycling process. However, the elongation at break of the recycled blends is higher compared with the virgin blends, possibly due to the plasticity effect of the low-molecular-weight chain fragments.
... Recyclates of mixed polyolefins and mixed size have less market value because of their nonspecific properties. Recyclates having uniform size and mono polyolefin waste are high in demand in the composite industries [29]. China imported over 7 Mt of plastic waste before its plastic waste import cut-down policy in 2017. ...
The interest in sustainable materials and technologies has increased significantly due to environmental issues triggered by using plastics and their associated wastes. Every year more than 400 million metric tons (Mt) of plastic production takes place globally, out of which 350 Mt plastic convert into plastic waste. Plastic waste mostly consists of polyolefin and their contribution to plastic waste is approximately 50%. Therefore, this review is focused on upcycling polyolefin waste by manufacturing natural/sustainable filler-based biocomposites. This is the novelty of the present review as a detailed review of the manufacturing of polyolefin waste-based biocomposites and their 3D printing suitability is not available in the literature. Natural filler-based biocomposites reduce the use of synthetic filler and help to move towards sustainability goals. This review starts with an overview of plastic waste generation and recycling techniques. A detailed discussion has been done on manufacturing waste polyolefin-based biocomposites and the effect of various fillers and compatibilizers on different properties. These biocomposites are found to be used for trays, packaging boxes, reusable bags, false ceilings, flooring, boundary walls, tiles, cabinets, chairs, tables, doors, designer pots, and automotive interior applications. In the later section, the scope of additive manufacturing of recycled polyolefin waste-based biocomposites along with their associated problems and their solution is also discussed. This review is concluded with the future potential of polyolefin waste upcycling in the sustainable filler-based biocomposites manufacturing sector.
... To produce energy, carbon-based mixed plastic wastes are usually incinerated in quaternary recycling (Oliveux et al., 2015;Ragaert et al., 2017;Zeller et al., 2021). Recycling has benefits such as reducing environmental pollution at an industrial scale and saving materials and energy (Achukwu et al., 2015a;Jones et al., 2021). Thus, some researchers have adopted energy recovery as a management method for mixed plastic wastes (MPW) especially when recycling involves expensive or challenging plastic sorting procedures (Kumar et al., 2011;Bujak, 2015). ...
Industrial plastic waste is growing globally at an alarming rate and environmental pollution from traditional landfill disposal and incineration treatments are of great concern. As a strategy to reduce plastic pollution, value-added composite materials from industrial plastic wastes reinforced with recycled nylon fibers for use in floor paving tile applications were developed. This is to address the disadvantages of existing ceramic tiles which are relatively heavy, brittle, and expensive. The plastic waste composite structures were produced via compression molding technique at an optimized randomly oriented constant fiber volume fraction of 50 wt% after the initial sorting, cleaning, drying, pulverizing , and melt-mixing. The molding temperature, pressure, and time for the composite's structures were 220 ℃, 65 kg.cm − 3 , and 5 min respectively. The composites' thermal, mechanical, and microstructural properties were characterized in accordance with appropriate ASTM standards. From the results obtained, the differential scanning calorimetry (DSC) of mixed plastic wastes and nylon fiber wastes showed a processing temperature range of 130-180 ℃, and 250 ℃ respectively. Thermal degradation temperature (TGA) of the plastic and nylon fiber waste composites were stable above 400 ℃ with maximum bending strength, however, the reinforced plastic waste sandwiched composite structures had outstanding mechanical properties indicating unique characteristics suitable for floor paving tiles. Hence, the current research has developed tough and lightweight tiles composites that are economically viable, and their application will contribute to the development of the building and construction sectors thereby reducing about 10-15% of annual plastic waste generation and a sustainable environment.
... However, this method largely deforms the plastics, which means that the recycled material has a limited range of application. Nevertheless, further innovation of this method and addition of plant fibres in the recycled material could increase its applicability [17]. ...
Recycled plastic and its use are imperative for preserving the environment, including proper plastic wash-out. Will we ever be able to push the Czech population and firms to use recycled material? Or is it happening spontaneously? A questionnaire created on Google Forms involves ten legislative and motivational questions comprising relevant data on the amount of plastic in municipal waste between 2010 and 2020 from the Czech Statistical Office. We found that the population understands the importance of using recycled material and recycled plastic without the government's impulse. Despite the high capital intensity, the state should impose taxes to protect the sustainable environment. We suggest a comprehensive and in-depth survey to acquire more accurate data.
... It seems that the reuse of waste as aggregate for concrete may bring positive effects both in terms of the possibility of recycling waste and in terms of the protection of natural resources [6][7][8]. It is particularly important to manage plastic waste in this way, as it is known that the world's dependence on plastic is still growing [8][9][10]. ...
The article contains the results of selected tests of physical and mechanical properties of mortars differentiated in terms of the binder used: cement, epoxy, epoxy modified with PET waste glycolysate and polyester. Each type of mortar was modified by partial (0–20% vol.) substitution of sand with an agglomerate made from waste polyethylene. The obtained results were used to build a database of mortar properties, which was then analyzed with the use of three different techniques of knowledge extraction from databases, i.e., cluster analysis, decision trees and discriminant analysis. The average results of the properties tested were compared, taking into account the type of mortar, indicating those with the most favorable parameters. The possibilities and correctness of mortar classification with the use of the indicated “data mining” methods were compared. The results obtained confirmed that it is possible to successfully apply these methods to the classification of construction mortars and then to propose mortars with such a composition that will guarantee that the composite will have the expected properties. Both the presented method of plastic waste management and the proposed statistical approach are in line with the assumptions of the currently important concept of sustainable development in construction.
... Mixed polyolefins obtained by mechanical recycling consist of various grades, mainly LDPE, HDPE, PP. 7,8 Knowing the precise chemical composition of individual batches is essential for processing and compounding. Differential scanning calorimetry (DSC) provides crucial material information, in particular melting and crystallization temperatures, which are valuable for processing. ...
The sorting stage of mechanical recycling of post‐consumer polyolefins has severe challenges. Polypropylene (PP) is often contaminated with polyethylene (PE) and vice versa. To meet quality requirements, characterization of the recycled pellets is needed. To address this problem, fast characterization generating a statistical assessment of the content of the various batches from recycling is required. This investigation shows that the use of fast scanning rates (in a conventional Differential Scanning Calorimeter) in the successive self‐nucleation and annealing (SSA) protocol can reduce the thermal fractionation time, without losing resolution power, as long as the increase in heating/cooling rate is compensated by reducing sample mass. Using a “coupled SSA protocol” for polypropylene and polyethylene fractions at a rate of 10 °C/min, the measurement time is approximately 420 min. Implementing mass compensation, faster heating rates (i.e., 30 °C/min) and using a single‐fraction protocol, sufficient to determine the content of PP and high‐density PE, reduced the time of the measurement to 75 min. Examples of fractionations of commercial post‐consumer and post‐industrial recycled polyolefin blends conducted at a faster rate are provided. The derived polyolefin content is compared with the standard temperature rising elution fractionation analysis to assess the validity of the proposed method.
У харчовій промисловості для пакування продукції використовують різні види тари. Вагоме місце посідає полімерна тара, яка має низку переваг і зручностей у застосуванні, але як одноразова створює високі екологічні ризики забруднення навколишнього середовища. Сучасні тенденції до зниження залежності від одноразової тари супроводжуються впровадженням новітніх технологій, які дозволяють використовувати при виготовленні полімерної тари не лише первинну сировину в чистому вигляді, але і її суміші із вторинною в різних пропорціях. Кількість вторинної сировини може досягати 70 %, а іноді й більше, що, безперечно, знижує негативний вплив полімерних відходів на стан навколишнього середовища і здоров’я людей. У статті наведено результати дослідження безпечності використання пляшок, виготовлених повністю з вторинного поліетилентерефталату, для пакування молока 2,5%-вої жирності, спиртовмісної продукції з вмістом спирту 5% і 40%, а також водних розчинів оцтової і молочної кислоти різної концентрації. Визначені показники міграції у досліджувані середовища ацетальдегіду, ацетону, бутанолу, ізопропанолу, метанолу, етилбензолу, диметилтерефталату та інших токсичних компонентів відповідають встановленим гігієнічним нормативам і не перевищують допустимої кількості міграції. Пляшки, виготовлені повністю з вторинної сировини, відповідають вимогам до тари, що контактує з харчовими продуктами, і можуть бути рекомендовані для пакування досліджуваних типів продукції.
Thermoformed products bear great potential for the application of recycled materials when using multilayer structures for incorporating post‐consumer recyclates. For this study, four different commercially available polypropylene recyclates are selected as possible core layers for the processing of multilayer thermoformed products with top layers of virgin polypropylene. Tests are performed on material level as well as on product level. At the material level, recyclates exhibit different mechanical property profiles with lower stiffness but higher toughness values due to polyethylene contamination. At the product level, thermoformed cups with core layers of recyclate material show lower shrinkage than cups made from polypropylene virgin material only. Most cups with recycled content achieve lower top load than the control cup. Based on these results, three strategies for improving product performance are defined and tested. Namely, (i) the use of a higher share of top layers, (ii) the blending of the recyclate core layer with a polypropylene virgin material with higher stiffness, and (iii) the increase in overall film thickness. All the strategies to adjust the film structure achieve better results in terms of shrinkage behavior and top load. However, the strategy that focuses on increasing the overall film thickness is not economically feasible.
