Editorial

4 pages, 161 KiB

Open AccessEditorial

Special Issue “Advances in Thermal and Mechanical Properties of Polymeric Materials”

by Agnieszka Kijo-Kleczkowska and Adam Gnatowski

Materials 2024, 17(1), 79; https://doi.org/10.3390/ma17010079 - 23 Dec 2023

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The Special Issue “Advances in Thermal and Mechanical Properties of Polymeric Materials” aimed to publish papers that deal with the thermomechanical and electrical properties of polymers and their composites with other materials [...] Full article

(This article belongs to the Special Issue Advances in Thermal and Mechanical Properties of Polymeric Materials)

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13 pages, 1946 KiB

Open AccessArticle

Experimental Measurement of the Thermal Conductivity of Fused Deposition Modeling Materials with a DTC-25 Conductivity Meter

by Antonio Rodriguez, Juan Pablo Fuertes, Añaterve Oval and Gurutze Perez-Artieda

Materials 2023, 16(23), 7384; https://doi.org/10.3390/ma16237384 - 27 Nov 2023

Cited by 1 | Viewed by 656

Abstract

The expansion and low cost of additive manufacturing technologies have led to a revolution in the development of materials used by these technologies. There are several varieties of materials that can be used in additive manufacturing by fused deposition modeling (FDM). However, some [...] Read more.

The expansion and low cost of additive manufacturing technologies have led to a revolution in the development of materials used by these technologies. There are several varieties of materials that can be used in additive manufacturing by fused deposition modeling (FDM). However, some of the properties of these materials are unknown or confusing. This article addresses the need to know the thermal conductivity in different filaments that this FDM technology uses, because there are multiple applications for these additive manufacturing products in the field of thermal insulation. For the study of thermal conductivity, the DTC-25 commercial conductivity measurement bench was used, where the tests were carried out on a set of seven different materials with 100% fabrication density—from base materials such as acrylonitrile butadiene styrene (ABS) or polylactic acid (PLA), to materials with high mechanical and thermal resistance such as thermoplastic polyurethane (TPU), polyether ether ketone (PEEK), and high-performance polyetherimide thermoplastic (ULTEM), to materials with metal inclusions (aluminum 6061) that would later be subjected to thermal after-treatments. This study shows how the parts manufactured with aluminum inclusions have a higher thermal conductivity, at 0.40 ± 0.05 W/m·K, compared to other materials with high mechanical and thermal resistance, such as TPU, with a conductivity of 0.26 ± 0.05 W/m·K. Full article

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15 pages, 6250 KiB

Open AccessEditor’s ChoiceArticle

From Transparent to Opaque: A Route towards Multifunctional Parts Injected with a Single Material

by Luís D. Pedroso, António J. Pontes, António Alves, Fernando M. Duarte and Olga S. Carneiro

Materials 2023, 16(18), 6219; https://doi.org/10.3390/ma16186219 - 15 Sep 2023

Cited by 1 | Viewed by 854

Abstract

The technological, social and economic development observed in recent decades brought an exponential increase in consumption and inherent new challenges. Recycling is one of the best solutions to minimize the environmental impact of raw materials. However, multi-material components are difficult or even impossible [...] Read more.

The technological, social and economic development observed in recent decades brought an exponential increase in consumption and inherent new challenges. Recycling is one of the best solutions to minimize the environmental impact of raw materials. However, multi-material components are difficult or even impossible to recycle. The present work focuses on the reduction in the number of different materials used in multifunctional components. In particular, it intends to assess the potential of injecting molding grades of polypropylene (PP) to produce parts with transparency (haze) gradients. Firstly, several polypropylene grades of different types were identified and injected under various thermal processing conditions, i.e., injection temperature and mold temperature, in order to vary the cooling rate, influencing the growth rate of the spherulites and eventually the presence/absence of α and β crystalline zones. The injected parts’ optical properties were then characterized, and the most promising PP grades were identified and selected for subsequent work, namely grade DR 7037.01, showing the widest range of haze (from 29.2 to 68.7%). and PP070G2M, presenting the highest haze value (75.3%). Finally, in an attempt to understand the origin of the haze variations observed, the parts injected with the selected PP grades were further characterized through differential scanning calorimetry (DSC) and polarized light microscopy. It was concluded that the main factor causing the observed haze difference was, apart from the size of the spherulites, the presence of internal layers with different birefringence and, therefore, different refractive indices. Full article

(This article belongs to the Special Issue Advances in Thermal and Mechanical Properties of Polymeric Materials)

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18 pages, 6982 KiB

Open AccessArticle

Research on Waste Combustion in the Aspect of Mercury Emissions

by Agnieszka Kijo-Kleczkowska, Adam Gnatowski, Barbara Tora, Krzysztof Kogut, Krzysztof Bytnar, Jaroslaw Krzywanski and Dorota Makowska

Materials 2023, 16(8), 3213; https://doi.org/10.3390/ma16083213 - 19 Apr 2023

Cited by 4 | Viewed by 1128

Abstract

The topic of waste combustion/co-combustion is critical, given the increasingly restrictive legal regulations regarding its environmental aspects. In this paper, the authors present the test results of selected fuels of different compositions: hard coal, coal sludge, coke waste, sewage sludge, paper waste, biomass [...] Read more.

The topic of waste combustion/co-combustion is critical, given the increasingly restrictive legal regulations regarding its environmental aspects. In this paper, the authors present the test results of selected fuels of different compositions: hard coal, coal sludge, coke waste, sewage sludge, paper waste, biomass waste and polymer waste. The authors conducted a proximate and ultimate analysis of the materials and mercury content in them and their ashes. An interesting element of the paper was the chemical analysis of the XRF of the fuels. The authors conducted the preliminary combustion research using a new research bench. The authors provide a comparative analysis of pollutant emissions—especially mercury emission—during the combustion of the material; this is an innovative element of this paper. The authors state that coke waste and sewage sludge are distinguished by their high mercury content. The value of Hg emission during the combustion depends on the initial mercury content in the waste. The results of the combustion tests showed the adequacy of mercury release compared to the emissions of other compounds considered. Small amounts of mercury were found in waste ashes. The addition of a polymer to 10% of coal fuels leads to a reduction in mercury emissions in exhaust gases. Full article

(This article belongs to the Special Issue Advances in Thermal and Mechanical Properties of Polymeric Materials)

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21 pages, 6625 KiB

Open AccessArticle

Research into Specific Mechanical Properties of Composites Produced by 3D-Printing Additive Continuous-Fiber Fabrication Technology

by Peter Pokorný, Daynier Rolando Delgado Sobrino, Štefan Václav, Jana Petru and Rafał Gołębski

Materials 2023, 16(4), 1459; https://doi.org/10.3390/ma16041459 - 09 Feb 2023

Cited by 2 | Viewed by 1938

Abstract

This paper introduces novel research into specific mechanical properties of composites produced by 3D printing using Continuous-Fiber Fabrication (CFF). Nylon (Onyx) was used as the composite base material, while carbon constituted the reinforcement element. The carbon fiber embedment was varied in selected components [...] Read more.

This paper introduces novel research into specific mechanical properties of composites produced by 3D printing using Continuous-Fiber Fabrication (CFF). Nylon (Onyx) was used as the composite base material, while carbon constituted the reinforcement element. The carbon fiber embedment was varied in selected components taking values of 0°, 45°, 90°, and 135° for parts undergoing tensile testing, while one specific part type was produced combining all angles. Carbon-fiber-free components with 100% and 37% fillings were also produced for comparison purposes. Parts undergoing the Charpy impact test had the fibers deposited at angles of 0° and 90°, while one part type was also produced combining the four angles mentioned before. Carbon-fiber-free parts with 100% and 37% fillings were also produced for comparison purposes as with the first part. The Markforged MARK TWO 3D printer was used for printing the parts. These were subsequently scanned in the METROTOM 1500 computed tomography and submitted to the tensile and impact tests. The results showed that adding carbon fiber to the base material increased the volume of defects in the samples as a result of the porosity increase. Although the tensile testing manifested an overall increase in tensile strength Rm of up to 12 times compared to the sample without reinforcement, it was proven that an improper fiber orientation significantly diminished the strength and that combining the four selected angles did not lead to the highest strength values. Finally, the impact tests also showed that fiber-reinforced parts implied up to 2.7 times more work to fracture, and that an improved fiber orientation also led to strength reduction. Full article

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14 pages, 3193 KiB

Open AccessArticle

Assessment of the Impact of Superficial Contamination and Thermo-Oxidative Degradation on the Properties of Post-Consumer Recycled Polypropylene

by Laura Prior, Mónica S. A. Oliveira and Tatiana Zhiltsova

Materials 2023, 16(3), 1198; https://doi.org/10.3390/ma16031198 - 31 Jan 2023

Cited by 2 | Viewed by 1671

Abstract

Single-use plastics are a matter of convenience in everyday life, with the majority allocated to packaging production. However, it comes with a high environmental price as its mass recycling is challenging due to the heterogeneity of composition, contaminations of different kinds, and degradation [...] Read more.

Single-use plastics are a matter of convenience in everyday life, with the majority allocated to packaging production. However, it comes with a high environmental price as its mass recycling is challenging due to the heterogeneity of composition, contaminations of different kinds, and degradation caused by service and processing. This study aims to ascertain the impact of removing contaminants from post-consumer recycled polypropylene (rPP) on its degradation and properties by implementing a systematic approach for decontamination by washing. Four lots of recycled plastics with different degrees of contamination were evaluated via Fourier transform infrared, melt flow indexer, and differential scanning calorimetry and tested for tensile strength. Degradation of the rPP was manifested by the deterioration in ductility, resulting in 14.58% elongation at break (unwashed rPP) compared with 191.41% (virgin PP)) and a significant reduction in oxidation induction time. In the unwashed rPP sample, a wave intensity peak at 1730 cm⁻¹, assigned to the saturated C = 0 stretch of the carbonyl functional group, was detected. This peak was gradually disappearing with an increase in the cleaning efficiency of rPP, highlighting the role of contaminants as degradation catalysts. The cold-washing method showed similar processing and mechanical performance improvement results compared with the other washing methods, while being more environmentally friendly and energy efficient. Full article

(This article belongs to the Special Issue Advances in Thermal and Mechanical Properties of Polymeric Materials)

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17 pages, 4960 KiB

Open AccessArticle

Influence of Air Humidity Level on the Structure and Mechanical Properties of Thermoplastic Starch-Montmorillonite Nanocomposite during Storage

by Natália Šmídová, Hamed Peidayesh, Anton Baran, Oľga Fričová, Mária Kovaľaková, Ružena Králiková and Ivan Chodák

Materials 2023, 16(3), 900; https://doi.org/10.3390/ma16030900 - 17 Jan 2023

Cited by 9 | Viewed by 1352

Abstract

Thermoplastic starch (TPS) consisting of corn starch and glycerol as a plasticizer, and TPS-montmorillonite (MMT) nanocomposite were stored at room temperature in the air with relative humidities (RH) of 11, 55 and 85% for seven weeks. Mechanical testing and dynamic mechanical thermal analysis [...] Read more.

Thermoplastic starch (TPS) consisting of corn starch and glycerol as a plasticizer, and TPS-montmorillonite (MMT) nanocomposite were stored at room temperature in the air with relative humidities (RH) of 11, 55 and 85% for seven weeks. Mechanical testing and dynamic mechanical thermal analysis (DMTA) were performed to detect changes in their mechanical properties. Solid-state NMR spectroscopy monitoring the changes in molecular mobility in the samples provided an insight into relations between mechanical properties and local structure. The results of mechanical testing indicated that the addition of MMT results in the increase in the tensile strength and Young’s modulus while elongation at break decreased, indicating the reinforcing effect of MMT. DMTA experiments revealed a decrease in glass transition temperature of starch-rich phase below room temperature for samples stored at higher RH (55 and 85%). This indicates that absorbed water molecules had additional plasticizing effect on starch resulting in higher mobility of starch chain segments. Recrystallization in these samples was deduced from the shape of cross-polarization magic-angle spinning ¹³C NMR spectra. The shape of broad-line ¹H NMR spectra reflected changes in molecular mobility in the studied samples during seven weeks of storage and revealed that a high amount of water molecules impacts the starch intermolecular hydrogen bond density. Full article

(This article belongs to the Special Issue Advances in Thermal and Mechanical Properties of Polymeric Materials)

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17 pages, 3818 KiB

Open AccessArticle

Characterization and under Water Action Behaviour of a New Plaster-Based Lightened Composites for Precast

by Manuel Álvarez, Daniel Ferrández, Patricia Guijarro-Miragaya and Carlos Morón

Materials 2023, 16(2), 872; https://doi.org/10.3390/ma16020872 - 16 Jan 2023

Cited by 6 | Viewed by 1372

Abstract

Plaster is a construction material widely used for the production of prefabricated parts in building construction due to its high capacity for hygrothermal regulation, its good mechanical performance, and its fireproof nature, among other factors. Its historical use has been linked to ornamental [...] Read more.

Plaster is a construction material widely used for the production of prefabricated parts in building construction due to its high capacity for hygrothermal regulation, its good mechanical performance, and its fireproof nature, among other factors. Its historical use has been linked to ornamental elements, although more recent research is oriented towards the industrialisation of plaster composites and the design of prefabricated parts for false ceilings and interior partitions. In this work, the behaviour against water of four new plaster-based composite materials is studied, using additions of two types of super absorbent polymers (sodium polyacrylate and potassium polyacrylate) and a lightening material (vermiculite) in their manufacturing process. In addition, the transmission of water vapour through the samples was studied together with the water absorption capacity of the samples in order to check the suitability of the use of plaster-based materials exposed to these environments. The results of this study show that composites with the addition of super absorbent polymers as well as vermiculite significantly improve their water performance compared to traditional materials up to 7.3% water absorption with a minimal (13%) reduction in mechanical strength compared to current materials with similar additions. In this sense, a plaster material is obtained with wide possibilities of application in the construction sector that favours the development of sustainable and quality buildings, in line with Goal 9 for Sustainable Development included in the 2030 Agenda. Full article

(This article belongs to the Special Issue Advances in Thermal and Mechanical Properties of Polymeric Materials)

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18 pages, 4311 KiB

Open AccessArticle

A Top-Down Approach and Thermal Characterization of Luminescent Hybrid BPA.DA-MMA@Ln₂L₃ Materials Based on Lanthanide(III) 1H-Pyrazole-3,5-Dicarboxylates

by Renata Łyszczek, Dmytro Vlasyuk, Beata Podkościelna, Halina Głuchowska, Ryszard Piramidowicz and Anna Jusza

Materials 2022, 15(24), 8826; https://doi.org/10.3390/ma15248826 - 10 Dec 2022

Cited by 5 | Viewed by 935

Abstract

In this study, novel hybrid materials exhibiting luminescent properties were prepared and characterized. A top-down approach obtained a series of polymeric materials with incorporated different amounts (0.1; 0.2; 0.5; 1, and 2 wt.%) of dopants, i.e., europium(III) and terbium(III) 1H-pyrazole-3,5-dicarboxylates, as luminescent sources. [...] Read more.

In this study, novel hybrid materials exhibiting luminescent properties were prepared and characterized. A top-down approach obtained a series of polymeric materials with incorporated different amounts (0.1; 0.2; 0.5; 1, and 2 wt.%) of dopants, i.e., europium(III) and terbium(III) 1H-pyrazole-3,5-dicarboxylates, as luminescent sources. Methyl methacrylate and bisphenol A diacrylate monomers were applied for matrix formation. The resulting materials were characterized using Fourier transform infrared spectroscopy (FTIR) and thermal analysis methods (TG-DTG-DSC, TG-FTIR) in air and nitrogen atmosphere, as well as by luminescence spectroscopy. The homogeneity of the resulting materials was investigated by means of optical microscopy. All obtained materials exhibited good thermal stability in both oxidizing and inert atmospheres. The addition of lanthanide(III) complexes slightly changed the thermal decomposition pathways. The main volatile products of materials pyrolysis are carbon oxides, water, methyl methacrylic acid and its derivatives, bisphenol A, 4-propylphenol, and methane. The luminescence properties of the lanthanide complexes and the prepared hybrid materials were investigated in detail. Full article

(This article belongs to the Special Issue Advances in Thermal and Mechanical Properties of Polymeric Materials)

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13 pages, 3705 KiB

Open AccessArticle

Thermal and Stress Properties of Briquettes from Virginia Mallow Energetic Crops

by Marek Kurtyka, Magdalena Szwaja, Andrzej Piotrowski, Barbara Tora and Stanislaw Szwaja

Materials 2022, 15(23), 8458; https://doi.org/10.3390/ma15238458 - 28 Nov 2022

Cited by 1 | Viewed by 1067

Abstract

The article discusses the influence of briquetting/compaction parameters. This includes the effects of pressure and temperature on material density and the thermal conductivity of biomass compacted into briquette samples. Plant biomass mainly consists of lignin and cellulose which breaks down into simple polymers [...] Read more.

The article discusses the influence of briquetting/compaction parameters. This includes the effects of pressure and temperature on material density and the thermal conductivity of biomass compacted into briquette samples. Plant biomass mainly consists of lignin and cellulose which breaks down into simple polymers at the elevated temperature of 200 °C. Hence, the compaction pressure, compaction temperature, density, and thermal conductivity of the tested material play crucial roles in the briquetting and the torrefaction process to transform it into charcoal with a high carbon content. The tests were realized for samples of raw biomass compacted under pressure in the range from 100 to 1000 bar and at two temperatures of 20 and 200 °C. The pressure of 200 bar was concluded as the most economically viable in briquetting technology in the tests conducted. The conducted research shows a relatively good log relationship between the density of the compacted briquette and the compaction pressure. Additionally, higher compaction pressure resulted in higher destructive force of the compacted material, which may affect the lower abrasion of the material. Regarding heat transfer throughout the sample, the average thermal conductivity for the compacted biomass was determined at a value of 0.048 ± 0.001 W/(K∙m). Finally, the described methodology for thermal conductivity determination has been found to be a reliable tool, therefore it can be proposed for other applications. Full article

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18 pages, 6444 KiB

Open AccessArticle

Numerical Analysis of Transient Pressure Damping in Viscoelastic Pipes at Different Water Temperatures

by Qiang Sun, Zhilin Zhang, Yuebin Wu, Ying Xu and Huan Liang

Materials 2022, 15(14), 4904; https://doi.org/10.3390/ma15144904 - 14 Jul 2022

Cited by 6 | Viewed by 1120

Abstract

Water temperature affects the peak pressure damping of transient flows in viscoelastic pipes. Owing to the viscoelastic properties of pipes, the accuracy of peak pressure damping simulations hinges on both viscoelastic and frictional factors. In simulations, the influence of both factors on peak [...] Read more.

Water temperature affects the peak pressure damping of transient flows in viscoelastic pipes. Owing to the viscoelastic properties of pipes, the accuracy of peak pressure damping simulations hinges on both viscoelastic and frictional factors. In simulations, the influence of both factors on peak pressure damping at different water temperatures is unclear. In this study, the Kelvin–Voigt model with both a quasi-steady friction model and modified Brunone model was employed. Based on experimental data, the accuracy of simulated peak pressure damping was verified at four different water temperatures (13.8, 25, 31, and 38.5 °C). From the perspective of energy transfer and dissipation, the influence of viscoelastic and frictional factors on peak pressure damping were clarified, and the applicability of different friction models was determined based on the contributions of viscoelastic and frictional factors to peak pressure damping. The numerical results indicate that the viscoelastic properties of pipes have a greater impact on peak pressure damping than their frictional properties at 25, 31, and 38.5 °C. Higher temperatures result in a delay in the rate of work and a decrease in the frequency of work performed by viscoelastic pipes. Viscoelastic properties play a more important role than frictional ones in calculating peak pressure damping as the water temperature increases. In addition, the one-dimensional quasi-steady friction model can accurately simulate peak pressure damping within a specified water temperature range. Full article

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18 pages, 12036 KiB

Open AccessArticle

Material and Structural Functionalization of Knitted Fabrics for Sportswear

by Ivana Salopek Čubrić, Vesna Marija Potočić Matković, Željka Pavlović and Alenka Pavko Čuden

Materials 2022, 15(9), 3306; https://doi.org/10.3390/ma15093306 - 05 May 2022

Cited by 8 | Viewed by 2802

Abstract

Comfort is an important quality criterion, especially for sportswear. It influences well-being, performance and efficiency. The necessary dissipation of heat and air flow, at high metabolic rates, must be designed and planned in advance. The influence of structure, density, mass and thickness of [...] Read more.

Comfort is an important quality criterion, especially for sportswear. It influences well-being, performance and efficiency. The necessary dissipation of heat and air flow, at high metabolic rates, must be designed and planned in advance. The influence of structure, density, mass and thickness of fabric were considered as well as yarn material composition, yarn linear density, yarn evenness and yarn hairiness. The influence of the mentioned parameters on thermal properties and air permeability was calculated. From the correlation analysis, it can be concluded that yarn’s linear density, yarn short fibers hairiness, and mass per unit area of knitted fabric has the greatest impact on heat resistance. The yarn linear density, the yarn hairiness of the longer protruding fibers, and the thickness of the knitted fabric have the greatest impact on air permeability. A statistically significant model of multiple linear regression equations was offered to predict the thermal comfort of knitted fabric. Full article

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13 pages, 2913 KiB

Open AccessArticle

Analysis of Thermomechanical Properties of Polyethylene with Cement Addition

by Adam Gnatowski, Agnieszka Kijo-Kleczkowska, Łukasz Suchecki, Paweł Palutkiewicz and Jarosław Krzywański

Materials 2022, 15(4), 1587; https://doi.org/10.3390/ma15041587 - 20 Feb 2022

Cited by 2 | Viewed by 1926

Abstract

The paper undertakes preliminary research towards the identification of the use of plastic waste, taking into account the possibility of increasing their mechanical strength and reducing flammability, as well as reducing the emission of harmful compounds to the atmosphere through the addition of [...] Read more.

The paper undertakes preliminary research towards the identification of the use of plastic waste, taking into account the possibility of increasing their mechanical strength and reducing flammability, as well as reducing the emission of harmful compounds to the atmosphere through the addition of cement. This is extremely important not only from the point of view of the wide use of plastic products in the industry, but also their thermal utilization. The present study deals with the aspect of the utilization of waste polyethylene (HDPE) as a matrix in composites with filler in the form of cement at 5 and 10%. The composite samples were prepared by injection molding after the prior proper mixing of the components. Comparative thermomechanical (DSC, tensile strength, DMTA), microstructure and flammability results are presented for HDPE samples and their composites with cement. It was found that the addition of cement as a filler to polyethylene made it possible to obtain composites with good thermomechanical properties. Full article

(This article belongs to the Special Issue Advances in Thermal and Mechanical Properties of Polymeric Materials)

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