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An increased amount of textile waste will be available in the future, and its utilization requires attention from various perspectives. The re-utilization of textile waste in a second material cycle is an option for dealing with a global problem that puts stress on the urban environment. In this study, almost 30 kg of clothing were recycled as a raw material in the structure of a composite, whose structural properties were analyzed. The studied materials were made from high-density polyethylene (HDPE), anhydride modified polyethylene, lubricant, and either polyethylene terephthalate (PET) or rayon fibers from recycled clothes. The recycled clothes were identified by a near-infrared (NIR) analyzer, followed by treatment of size reduction and materials compounding by agglomeration and compression molding technologies. The material properties were characterized by thickness swelling, water absorption, impact, and tensile testing. The recycled clothes fibers, acting as a filler component in the structure of the composite, could maintain the properties of the material at the same level as the reference material. PET fibers being used as a component resulted in a significant improvement in impact strength. The study showed that recycled clothes can be re-utilized as a substitute for raw materials, and can be part of a solution for future challenges involving textile waste, following the principles of the circular economy. Textile recycling create opportunities to improve the quality of urban life.
Ville Lahtela; Anil Kumar; Timo Kärki. The Impact of Textile Waste on the Features of High-Density Polyethylene (HDPE) Composites. Urban Science 2021, 5, 59 .
AMA StyleVille Lahtela, Anil Kumar, Timo Kärki. The Impact of Textile Waste on the Features of High-Density Polyethylene (HDPE) Composites. Urban Science. 2021; 5 (3):59.
Chicago/Turabian StyleVille Lahtela; Anil Kumar; Timo Kärki. 2021. "The Impact of Textile Waste on the Features of High-Density Polyethylene (HDPE) Composites." Urban Science 5, no. 3: 59.
This paper investigated the moisture and strength properties of wood-polymer composites (WPC), which were made using three different recycled polymers using wood flour as filler. The recycled polymers were acrylonitrile butadiene styrene (ABS), polypropylene (PP), and polyethylene (PE), which were collected from among the construction and demolition waste (CDW) at a local waste management center. The commercial additives, such as a coupling agent and lubricant, were also included in the materials. Composite materials were manufactured with an agglomeration and an extrusion process. Water absorption and thickness swelling properties of composites, based on the recycled ABS and PE, were restricted compared to the recycled PP. The strength properties of WPC were determined with two methods, a traditional Brinell hardness and resistance to indentation. Using an ABS polymer as a matrix in the composite, the moisture and strength properties were improved. The recycled PP polymer caused these properties to be lowered, especially in the case of moisture properties. This study has shown that the method used can affect the measured value of certain properties. In addition, the sorting of recycled polymer fractions is desirable for the appearance of improved properties.
Ville Lahtela; Timo Kärki. A Study on the Effect of Construction and Demolition Waste (CDW) Plastic Fractions on the Moisture and Resistance to Indentation of Wood-Polymer Composites (WPC). Journal of Composites Science 2021, 5, 205 .
AMA StyleVille Lahtela, Timo Kärki. A Study on the Effect of Construction and Demolition Waste (CDW) Plastic Fractions on the Moisture and Resistance to Indentation of Wood-Polymer Composites (WPC). Journal of Composites Science. 2021; 5 (8):205.
Chicago/Turabian StyleVille Lahtela; Timo Kärki. 2021. "A Study on the Effect of Construction and Demolition Waste (CDW) Plastic Fractions on the Moisture and Resistance to Indentation of Wood-Polymer Composites (WPC)." Journal of Composites Science 5, no. 8: 205.
The weight of packaging materials will be increased with advanced innovations, such as multilayer plastic. The consequence of the advanced innovations is challenges in the following reuse activities. This study aimed to investigate the properties of multilayer plastic materials after recycling processes and will increase the awareness of plastic packaging material for reuse options. In this research, the materials were produced from food packages by crushing them and treating them with injection molding equipment. The implementation of materials in the processing was tested, and the structural and mechanical characteristics of the produced plastic materials was evaluated and discussed. Based on the completed tests, plastic materials used in food packages have the clearest differences in the material features, for instance, the melt flow rate and elongation rate in the tensile test that varied between 2.96–48.4 g/10min and 2–289 %, respectively. The variation in the characterizations ranged widely between the material structures. The results indicate that solid plastic packaging materials have better mechanical features compared to foil materials. The structural analysis of materials showed that multilayer plastic includes a wide spectrum of different elements within materials, creating a challenge for future recycling.
Ville Lahtela; Shekhar Silwal; Timo Kärki. Re-Processing of Multilayer Plastic Materials as a Part of the Recycling Process: The Features of Processed Multilayer Materials. Polymers 2020, 12, 2517 .
AMA StyleVille Lahtela, Shekhar Silwal, Timo Kärki. Re-Processing of Multilayer Plastic Materials as a Part of the Recycling Process: The Features of Processed Multilayer Materials. Polymers. 2020; 12 (11):2517.
Chicago/Turabian StyleVille Lahtela; Shekhar Silwal; Timo Kärki. 2020. "Re-Processing of Multilayer Plastic Materials as a Part of the Recycling Process: The Features of Processed Multilayer Materials." Polymers 12, no. 11: 2517.
Construction and demolition waste (CDW), including valuable materials such as plastics, have a remarkable influence on the waste sector. In order for plastic materials to be re-utilized, they must be identified and separated according to their polymer composition. In this study, the identification of these materials was performed using near-infrared spectroscopy (NIR), which identified material based on their physical-chemical properties. Advantages of the NIR method are a low environmental impact and rapid measurement (within a few seconds) in the spectral range of 1600-2400 nm without special sample preparation. Limitations include its inability to analyze dark materials. The identified polymers were utilized as a component for wood-polymer composite (WPC) that consists of a polymer matrix, low cost fillers, and additives. The components were first compounded with an agglomeration apparatus, followed by production by extrusion. In the agglomeration process, the aim was to compound all materials to produce uniformly distributed and granulated materials as pellets. During the agglomeration process, the polymer (matrix) was melted and fillers and other additives were then mixed into the melted polymer, being ready for the extrusion process. In the extrusion method, heat and shear forces were applied to a material within the barrel of a conical counter-rotating twin-screw type extruder, which reduces the risk of burning the materials and lower shear mixing. The heated and sheared mixture was then conveyed through a die to give the product the desired shape. The above-described protocol proved the potential for re-utilization of CDW materials. Functional properties must be verified according to the standardized tests, such as flexural, tensile, and impact strength tests for the material.
Ville Lahtela; Marko Hyvärinen; Timo Kärki. The Effect of Construction and Demolition Waste Plastic Fractions on Wood-Polymer Composite Properties. Journal of Visualized Experiments 2020, e61064 .
AMA StyleVille Lahtela, Marko Hyvärinen, Timo Kärki. The Effect of Construction and Demolition Waste Plastic Fractions on Wood-Polymer Composite Properties. Journal of Visualized Experiments. 2020; (160):e61064.
Chicago/Turabian StyleVille Lahtela; Marko Hyvärinen; Timo Kärki. 2020. "The Effect of Construction and Demolition Waste Plastic Fractions on Wood-Polymer Composite Properties." Journal of Visualized Experiments , no. 160: e61064.
The cost-efficient reutilization of byproduct materials is a significant global goal, contributing towards the sustainable use of resources. In this study, the effects of including primary sludge in composite materials on their physical performance are examined, in order to achieve more effective reuse. The studied materials were made from high-density polyethylene (HDPE), anhydride-grafted polyethylene (MAPE), lubricants, and either wood flour from spruce (Picea abies) or primary sludge from the side-stream of forest industry processes as a filler. The materials were compounded by agglomeration, followed by manufacturing with a conical twin-screw extruder. The physical properties of the materials were characterized by water absorption and thickness swelling tests; furthermore, impact strength was characterized after the stress of a cyclic freeze-thawing test. The elemental compositions of the materials were also analyzed by scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS). Primary sludge, as a component in the structure of the composite material, resulted in a significant improvement of moisture behaviors in the water absorption and thickness swelling tests. The identified results demonstrate that primary sludge is a technically applicable material for utilization in composite materials.
Kati Mustonen; Ville Lahtela; Timo Kärki. The Impact of Primary Sludge on the Physical Features of High-Density Polyethylene (HDPE) Composites. Resources 2019, 8, 184 .
AMA StyleKati Mustonen, Ville Lahtela, Timo Kärki. The Impact of Primary Sludge on the Physical Features of High-Density Polyethylene (HDPE) Composites. Resources. 2019; 8 (4):184.
Chicago/Turabian StyleKati Mustonen; Ville Lahtela; Timo Kärki. 2019. "The Impact of Primary Sludge on the Physical Features of High-Density Polyethylene (HDPE) Composites." Resources 8, no. 4: 184.
In this research, lignin and modified lignin were used as a biobased additive in the manufacturing of biocomposites. The biocomposites were produced from polylactic acid (PLA) and wood. Lignin used in this study was recovered both from spruce and from construction and demolition waste (CDW) by extracting it with a deep eutectic solvent (DES), and part of the recovered lignin was modified in esterification with maleic anhydride. The implementation of lignins on biobased composites in filament extrusion was tested and the influence of lignin on the composite manufacturing process and mechanical characteristics of the produced biocomposites was evaluated and discussed. The results showed that lignin compounds can be used as a part of biocomposites based on PLA and wood material, because the lowest tensile strength was achieved with samples which did not contain any commercial coupling agent compounds. Lignin was found to act in the biocomposites more as a coupling agent than as a lubricant, and the coupling agent strength effect of esterified lignin was comparable to the commercial coupling agent used in these experiments. The best specific tensile strength of filaments achieved in this study were 7.68 and 7.71 MPa for materials that included commercial coupling agent and esterified lignin, respectively.
Ikenna Anugwom; Ville Lahtela; Mari Kallioinen; Timo Kärki. Lignin as a functional additive in a biocomposite: Influence on mechanical properties of polylactic acid composites. Industrial Crops and Products 2019, 140, 111704 .
AMA StyleIkenna Anugwom, Ville Lahtela, Mari Kallioinen, Timo Kärki. Lignin as a functional additive in a biocomposite: Influence on mechanical properties of polylactic acid composites. Industrial Crops and Products. 2019; 140 ():111704.
Chicago/Turabian StyleIkenna Anugwom; Ville Lahtela; Mari Kallioinen; Timo Kärki. 2019. "Lignin as a functional additive in a biocomposite: Influence on mechanical properties of polylactic acid composites." Industrial Crops and Products 140, no. : 111704.
This study investigated the suitability of mechanical pre-treatment methods (mechanical abrasion and treatments of heat, laser, and plasma) together with a hydrometallurgical process comprising leaching and cementation for recovering indium from used LCD screens. With mechanical abrasion pre-treatment, 96.2% of indium was recovered and black mass with an indium content of 15.6 wt percent was obtained. Following the mechanical recovery, sulfuric acid leaching was used to produce leachates with an indium purity ranging from 86.3 to 98.0% with an 88.7–100% yield for indium. Indium was recovered from the leachate by cementation with zinc powder, but also the impurity metals were cemented. The suggested mechanical pre-treatment involving the indium recovery process was seen as a viable option since it dramatically reduces the mass fed to the hydrometallurgical purification process (by roughly a factor of 1000), and up to 97.1% pure indium product can be obtained with a simplified process. The purity of the indium product can be further increased by additional purification steps.
Ville Lahtela; Sami Virolainen; Andreas Uwaoma; Mari Kallioinen; Timo Kärki; Tuomo Sainio. Novel mechanical pre-treatment methods for effective indium recovery from end-of-life liquid-crystal display panels. Journal of Cleaner Production 2019, 230, 580 -591.
AMA StyleVille Lahtela, Sami Virolainen, Andreas Uwaoma, Mari Kallioinen, Timo Kärki, Tuomo Sainio. Novel mechanical pre-treatment methods for effective indium recovery from end-of-life liquid-crystal display panels. Journal of Cleaner Production. 2019; 230 ():580-591.
Chicago/Turabian StyleVille Lahtela; Sami Virolainen; Andreas Uwaoma; Mari Kallioinen; Timo Kärki; Tuomo Sainio. 2019. "Novel mechanical pre-treatment methods for effective indium recovery from end-of-life liquid-crystal display panels." Journal of Cleaner Production 230, no. : 580-591.
Reuse of materials is a significant global goal that contributes to sustainable development. Polymer-specific plastic identification from the waste stream is examined in this study to achieve environmentally optimistic reuse of plastic material in secondary applications. Two diverse waste streams, 86.11 kg of construction and demolition waste (CDW) plastic and 57.74 kg of mechanically sorted plastic, were analyzed by using a handheld tool whose identification technology was based on the near-infrared spectrum. The study indicates a significant effect of human and single fraction on manual separation. The polymer composition in the plastic waste stream varied depending on the source, but the most common plastic grades, polypropylene (PP) and polyethylene (PE), were represented in every waste stream. The waste stream also included unidentified and unfavorable wastes, which indicates that identification of the plastic fractions is needed and more studies should be done in this field in the future.
Ville Lahtela; Marko Hyvärinen; Timo Kärki. Composition of Plastic Fractions in Waste Streams: Toward More Efficient Recycling and Utilization. Polymers 2019, 11, 69 .
AMA StyleVille Lahtela, Marko Hyvärinen, Timo Kärki. Composition of Plastic Fractions in Waste Streams: Toward More Efficient Recycling and Utilization. Polymers. 2019; 11 (1):69.
Chicago/Turabian StyleVille Lahtela; Marko Hyvärinen; Timo Kärki. 2019. "Composition of Plastic Fractions in Waste Streams: Toward More Efficient Recycling and Utilization." Polymers 11, no. 1: 69.
Ville Lahtela; Kati Mustonen; Timo Kärki. The effect of primary sludge on the mechanical performance of high-density polyethylene composites. Industrial Crops and Products 2017, 104, 129 -132.
AMA StyleVille Lahtela, Kati Mustonen, Timo Kärki. The effect of primary sludge on the mechanical performance of high-density polyethylene composites. Industrial Crops and Products. 2017; 104 ():129-132.
Chicago/Turabian StyleVille Lahtela; Kati Mustonen; Timo Kärki. 2017. "The effect of primary sludge on the mechanical performance of high-density polyethylene composites." Industrial Crops and Products 104, no. : 129-132.
Wood, as a natural and renewable resource, is a popular material for construction, but its fire performance restricts its utilization. In addition, for example, the mechanical properties of wood have up till now been impaired by the most common fire retardants, and therefore, the investigation of wood modification with not-weakening flame retardants is essential. This study investigates the effects of melamine impregnation and heat treatment on the fire performance of Scots pine (Pinus sylvetris L.). The treated samples were tested with a cone calorimeter, and the following features were studied: time to ignition, heat release, smoke production, and mass loss. The heat-treated samples became more homogenous as regards the results of fire performance. Some of the examined fire behavior values decreased because of heat treatment, while the same values increased after the combination of melamine impregnation and heat treatment. The smoke production was reduced the most for the samples that were both impregnated and heat treated. Although the influence of treatment on the fire behavior properties of solid wood was relatively marginal, it was assumed that these treatments will not have a negative impact on the fire-resistance properties of pine wood. Copyright © 2015 John Wiley & Sons, Ltd.
Ville Lahtela; Timo Kärki. The influence of melamine impregnation and heat treatment on the fire performance of Scots pine (Pinus sylvetris) wood. Fire and Materials 2015, 40, 731 -737.
AMA StyleVille Lahtela, Timo Kärki. The influence of melamine impregnation and heat treatment on the fire performance of Scots pine (Pinus sylvetris) wood. Fire and Materials. 2015; 40 (5):731-737.
Chicago/Turabian StyleVille Lahtela; Timo Kärki. 2015. "The influence of melamine impregnation and heat treatment on the fire performance of Scots pine (Pinus sylvetris) wood." Fire and Materials 40, no. 5: 731-737.
Wood modification, of which thermal modification is one of the best-known methods, offers possible improvement in wood properties without imposing undue strain on the environment. This study investigates improvement of the properties of heat-treated solid wood. Scots pine (Pinus sylvestris) was modified in two stages: impregnation with modifiers followed by heat treatment at different temperatures. The impregnation was done with water glass, melamine, silicone, and tall oil. The heat treatment was performed at the temperatures of 180°C and 212°C for three hours. The modified samples were analyzed using performance indicators and scanning electron microscope micrographs. The mechanical and physical properties were determined with water absorption, swelling, bending strength, and impact strength tests. All the modifiers penetrated better into sapwood than hardwood; however, there were significant differences in the impregnation behavior of the modifiers. As regards the effect of heat treatment, generally the moisture properties were improved and mechanical strengths impaired with increasing treatment temperature. In contrast to previous studies, the bending strength increased after melamine impregnation and mild heat treatment. It is concluded that the properties of impregnated wood can be enhanced by moderate heat treatment.
Ville Lahtela; Timo Kärki. Effects of impregnation and heat treatment on the physical and mechanical properties of Scots pine (Pinus sylvestris) wood. Wood Material Science & Engineering 2014, 11, 217 -227.
AMA StyleVille Lahtela, Timo Kärki. Effects of impregnation and heat treatment on the physical and mechanical properties of Scots pine (Pinus sylvestris) wood. Wood Material Science & Engineering. 2014; 11 (4):217-227.
Chicago/Turabian StyleVille Lahtela; Timo Kärki. 2014. "Effects of impregnation and heat treatment on the physical and mechanical properties of Scots pine (Pinus sylvestris) wood." Wood Material Science & Engineering 11, no. 4: 217-227.
Wood modification is commonly used to alter and improve wood properties. This study investigates the effects of impregnation modification with four environmentally nontoxic agents on the UV-resistance and water absorption properties of solid wood. Scots pine (Pinus sylvestris) was impregnated with modifiers by pressure device. The solid wood specimens were treated with water glass, silicone, melamine, and tall oil. The modified samples were analyzed by SEM microscopy, and thickness swelling, water absorption and UV resistance were determined. The penetration of the studied modifiers differed. The melamine-treated samples were found to exhibit the best impregnation, which also affected the wood properties favorably. The melamine-treated solid pine wood samples absorbed half of the water absorbed by wood treated with the other solutions and attained the best results in thickness swelling and weathering tests. It is concluded that impregnation modification of Scots pine is dependent on the nature of the modifier and based on the results of this study, melamine solution treatment is found to have a positive effect on the properties of solid pine wood.
Ville Lahtela; Timo Kärki. Improving the UV and water-resistance properties of Scots pine (Pinus sylvestris) with impregnation modifiers. European Journal of Wood and Wood Products 2014, 72, 445 -452.
AMA StyleVille Lahtela, Timo Kärki. Improving the UV and water-resistance properties of Scots pine (Pinus sylvestris) with impregnation modifiers. European Journal of Wood and Wood Products. 2014; 72 (4):445-452.
Chicago/Turabian StyleVille Lahtela; Timo Kärki. 2014. "Improving the UV and water-resistance properties of Scots pine (Pinus sylvestris) with impregnation modifiers." European Journal of Wood and Wood Products 72, no. 4: 445-452.