| 1. |
- Forsgren, Lilian, 1990, et al.
(författare)
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The thermo-oxidative durability of polyethylene reinforced with wood-based fibres
- 2020
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Ingår i: Polymer degradation and stability. - : Elsevier Ltd. - 0141-3910 .- 1873-2321. ; 181
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Tidskriftsartikel (refereegranskat)abstract
- Aiming at better understanding the ageing behaviour of cellulose composites, the accelerated thermo-oxidative ageing of polyethylene reinforced with two types of wood-based cellulose fibres was studied. Materials were prepared by extrusion mixing of either un-stabilized or stabilized polyethylene reinforced with 5 and 20 vol % cellulose content. The materials were extruded into strips and then aged at 90°C in circulating air. The effect of accelerated ageing up to 31 days was assessed by oxidation induction time and mechanical properties in tension. The results indicated that the added cellulose fibres did not increase the degradation of the composites during this ageing. Reinforcement with 20 % cellulose fibre having a 28 % lignin content together with 0.005 % Irganox 1010 antioxidant resulted in a remarkable improvement in the resistance against accelerated thermo-oxidation, compared to the pure polyethylene with added antioxidant. The findings of increased lifetime of LDPE by addition of wood-based reinforcement is of great interest, since the durability aspect is crucial to understand and predict before usage in commercial applications and especially as structural composites.
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| 2. |
- Boz Noyan, Ezgi Ceren, 1990, et al.
(författare)
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A comparison between laboratory-scale and large-scale high-intensity washing of flexible polyethylene packaging waste
- 2024
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Ingår i: Polymer Engineering and Science. - 0032-3888 .- 1548-2634. ; 64:4, s. 1877-1886
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Tidskriftsartikel (refereegranskat)abstract
- Sorted flexible polyethylene packaging waste was washed on a laboratory scale at both 25 and 40°C with water alone, with water and added NaOH, and with water and added detergent. The washed materials were then compounded using a twin-screw extruder and injection molded. The results were compared with those for an unwashed and a large-scale high-intensity sample washed with NaOH at 70–80°C. An intensive washing combined with high temperature gave a lower extensibility both in the molten and solid states presumably because of a greater degradation of the recycled material. Washing with NaOH resulted in the lowest strain-at-break in both the melt and solid states, whereas washing with water alone or with a detergent gave similar strain-at-break levels. The melt strength, the stiffness and tensile strengths at room temperature, and the thermal properties were less affected by the washing procedure. Although the final properties seem to be useful in general there were still some trade-offs between the washing condition and the degradation. While these results were expected, the influence of washing parameters on final product, for example, injection molded sample, has to our knowledge not been shown before especially regarding the mechanical properties. Highlights: Post-consumer flexible polyethylene packaging waste was studied with a focus on washing conditions. The influence of washing conditions on thermal, rheological, and mechanical properties of recycled samples was investigated. High-intensity washing at high temperature caused significant degradation of the material, this was to our understanding shown for the first time.
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| 3. |
- Boz Noyan, Ezgi Ceren, 1990, et al.
(författare)
-
Influence of washing media and temperature on the properties of recycled post-consumer flexible polyethylene packaging waste
- 2023
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Plastic packaging products, typically flexible film packaging, has been the largest application area for polymeric materials for many decades, constituting a major source of waste in society. Plastics packaging is also the fastest growing application area but considered to be the most challenging for material recycling. Complexities and challenges in recycling requires better understanding on influence of processing parameters, e.g., compounding and washing, on properties of the recycled materials made of post-consumer flexible plastic packaging waste. In our previous studies the focus was more on understanding first the properties of untreated post-consumer flexible polyethylene packaging waste and secondly the influence of selected compounding parameters. Two different temperature profiles and screw configurations were used in compounding to assess the influence. The results showed that the studied compounding parameters had no great influence on the melting temperature, crystallinity, stiffness and strength of the samples. However, thermo-oxidative degradation apparently occurred after washing especially with industrial-scale washing at 70-80°C and deteriorated further when compounded at a high temperature profile. The elongation at break of injection moulded samples made of unwashed waste increased with high temperature compounding but for the washed waste the opposite was observed. Overall results indicated the importance of washing step and its influence on final properties. The work continued with a focus on the influence of washing media and the temperature on properties of recycled post-consumer flexible polyethylene packaging waste. Laboratory-scale washing was done with three different washing medias: water, water + NaOH and water + detergent. Washings were done both at 25 and 40°C, referred to as hot and cold washing, respectively. The compounding and injection moulding parameters were kept the same for all samples and as in the previous work. The properties of intermediates and the moulded samples were analysed with high temperature gel permeation chromatography, capillary rheometry and both the thermal and mechanical properties were assessed. The results showed that neither the washing media nor the washing temperature studied in this work had a significant influence on the thermal properties of the samples. The oxidation induction temperatures were on a similar level for all samples, being between 225-232°C, implying that the samples still contained a significant amount of active stabilizers. Similarly, the viscosity curves were in a similar range which was supported with the melt-mass flow rate measurements. However, the pressure losses at capillary flow were differed indicating different elasticity of the melts. Rheotens type of measurements clearly showed differences in the tenacity of melts. Washing with NaOH resulted in the lowest strain at break for the melts whereas the washing with only water and with detergent showed similar levels of strain at break of melts. The melt strengths were in a similar range for all the samples. Concerning the mechanical properties of injection moulded samples, the elongation at break was the most influenced property, the samples washed with NaOH had the lowest values whereas the other washings resulted in mouldings with similar elongation at break. The Young’s modulus and the tensile strength values were less changed by the washings. In general the washing temperature had no major impact.
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| 4. |
- Boz Noyan, Ezgi Ceren, 1990
(författare)
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Material recycling of post-consumer flexible polyethylene packaging waste
- 2022
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The mechanical and thermal properties of recycled post-consumer flexible polyethylene packaging waste was studied, using material collected and sorted on a large-scale from two sources. Unwashed, laboratory-scale washed, industrial-scale washed, and industrial-scale washed and melt-compounded (industrially recycled) materials were used. The unwashed and washed flakes were melt-compounded on a laboratory scale with a twin-screw extruder using two different temperature profiles and two screw configurations. The pellets were then injection moulded. Washing reduced the polymer molecular mass and the melt viscosity, making the material susceptible to further degradation during melt-compounding and more so at a higher temperature. The Young’s modulus and tensile strength were affected by the washing but not by the compounding temperature or screw configuration, while the elongation-at-break were affected somewhat both by the washing and compounding temperature but not by the screw configuration. The moulded samples made of unwashed, laboratory-washed and industrial-washed materials had a stiffness, a tensile strength and an elongation-at-break as expected of conventional polyethylene grades available. The industrially recycled samples, however, had a lower stiffness, a slightly higher tensile strength and a significantly greater elongation-at-break. This significantly different mechanical properties of the industrially recycled material were probably due to the melt-filtration and possibly also to the additives in industrial melt-compounding. The overall results indicated that post-consumer flexible packaging waste had useful properties for further applications in new products, such as for non-food packaging.
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| 5. |
- Boz Noyan, Ezgi Ceren, 1990, et al.
(författare)
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Material recycling of post-consumer flexible polyethylene packaging waste
- 2023
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Ingår i: Book of Abstracts, 38th International Conference of the Polymer Processing Society. ; , s. 388-388
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The growing concern in society has led to ambitious targets set by EU directives for an increased rate of recycling on plastic packaging waste, however the challenges involved in material recycling require better understanding on the development of the performance of the material. The purpose of this work was to study the properties of post-consumer flexible polyethylene packaging waste, using material sorted on a large scale from two different sources. Unwashed, laboratory-scale washed, industrial-scale washed, and industrial-scale washed and melt-compounded (industrially recycled) materials were used. The unwashed and washed flakes were melt-compounded on a laboratory scale with a twin-screw extruder using two different temperature profiles and two screw configurations. The pellets were then injection moulded into a shape of a frame with the purpose to obtain different material structures: sections with a mixed molecular orientation, a unidirectional flow and a weld line. The characteristics of the pellets were analysed with GPC, MFR and capillary rheometry. Moreover, the degradation status, thermal and mechanical properties of the samples were assessed. The washing reduced the polymer molecular mass and the melt viscosity, making the material susceptible to further degradation during melt-compounding and more so at a higher temperature. The Young’s modulus and tensile strength were affected by the washing but not by the compounding temperature or screw configuration, while the elongation at break were affected somewhat both by the washing and compounding temperature but not by the screw configuration. The moulded samples made of unwashed, laboratory-washed and industrial-washed materials had a stiffness, a tensile strength and an elongation at break as expected of conventional polyethylene grades available. The industrially recycled samples, however, had a lower stiffness, a slightly higher tensile strength and a significantly greater elongation at break. This significantly different mechanical properties of the industrially recycled material were probably due to the degradation at recycling processing, possibly also to the additives in industrial melt-compounding.
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| 6. |
- Boz Noyan, Ezgi Ceren, 1990, et al.
(författare)
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Mechanical and Thermal Properties of Mixed PE Fractions from Post-Consumer Plastic Packaging Waste
- 2022
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Ingår i: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 7:49, s. 45181-45188
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Tidskriftsartikel (refereegranskat)abstract
- The functional properties of recycled post-consumer flexible polyethylene packaging waste have been studied using materials collected and sorted at a large-scale facility in Sweden. The studied fraction was used both as received and after simple laboratory washing in water with added sodium hydroxide at 40 °C. The materials were melt-compounded with a twin-screw extruder using two different temperature profiles and two screw configurations and injection-molded into slabs, whose thermal and mechanical properties were assessed. The results showed that the mechanical properties of injection-molded samples were not changed significantly either by the washing or by the temperature or screw configuration used in the compounding. Washing reduced the viscosity and molecular mass to a minor extent. As expected, the ash content of the compounded pellets was reduced by washing. The thermo-oxidative stability decreased with increasing compounding temperature and with washing.
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| 7. |
- Boz Noyan, Ezgi Ceren, 1990, et al.
(författare)
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Rheological and Functional Properties of Mechanically Recycled Post-Consumer Rigid Polyethylene Packaging Waste
- 2024
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Ingår i: Materials. - 1996-1944. ; 17:8
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Tidskriftsartikel (refereegranskat)abstract
- The properties of recycled post-consumer rigid polyethylene packaging waste were studied, using sorted waste washed in the laboratory with water alone and with added detergent, and compared with large-scale high-intensity washed flakes. The washed flakes were compounded using three different temperature profiles in a twin-screw extruder and then injection molded. A higher compounding temperature reduced the thermo-oxidative stability, the average molecular mass, and the viscosity of the samples. Rheological measurements suggested that changes in chain branching occurred at different compounding temperatures. The strength and the elongation at break were also influenced by the compounding temperature in both the molten and solid states. Detergent washing maintained the thermo-oxidative stability in contrast to washing with water. The large-scale washed samples had a relatively high thermo-oxidative stability, a higher melt elasticity, and a lower elongation at break in both the molten and solid states than the laboratory-scale washed samples. The thermal properties, melt elasticity, Young’s modulus, yield stress, and yield strain of the samples were not, however, significantly affected by either the compounding temperature or the washing medium and intensity. The results indicated that recycled post-consumer rigid polyethylene packaging waste has properties that can support further applications in new products.
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| 8. |
- Boz Noyan, Ezgi Ceren, 1990, et al.
(författare)
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Washing Post-Consumer Flexible Polyethylene Packaging Waste
- 2022
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Ingår i: Recycling. - : MDPI. - 2313-4321. ; 7:6
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Tidskriftsartikel (refereegranskat)abstract
- The mechanical and thermal properties of injection-molded recycled polyethylene were studied, specifically with respect to the influence of large-scale washing and melt-compounding of polyethylene from post-consumer packaging waste. Three types of materials were studied: those taken after sorting, after sorting and washing, and after sorting, washing, and melt-compounding, including melt-filtration, all from a large-scale material flow. The materials were further processed on a laboratory scale and compared. The results showed that large-scale washing significantly reduced thermo-oxidative stability, as well as molar mass and melt viscosity. The degradation during large-scale washing made the material susceptible to further degradation in the subsequent extrusion compounding, as shown by the differences in compounding at 240 and 200 °C using a high-shear screw configuration. The compounding parameters, screw configuration, and compounding temperature did not influence the stiffness and strength of the unwashed and large-scale-washed materials, but the elongation-at-break varied, specifically, with the increased temperature. Washing had an influence on the mechanical properties as well, and the unwashed material provided molded samples with stiffness measurements of approximately 550 MPa, whereas the large-scale-washed material provided stiffness of approximately 400 MPa. The strength measurements were approximately 15 MPa for samples made of both unwashed and large-scale-washed material, and the elongation-at-break measurements were between 50 and 150%. The large-scale-washed and compounded materials had very different mechanical properties, with stiffness measurements of approximately 320 MPa, strength of approximately 20 MPA, and elongation-at-break of approximately 350%. The significantly different mechanical properties of the large-scale-washed and compounded materials were likely due to the melt-filtration included in the compounding through the removal of metal and rubber particles, and they may also have been due to the compatibilizing and stabilizing additive used in the compounding. © 2022 by the authors.
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