Materials

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15 pages, 3690 KiB

Open AccessArticle

Physical-Mechanical Properties of Peat Moss (Sphagnum) Insulation Panels with Bio-Based Adhesives

by Marco Claudius Morandini, Günther Kain, Jonas Eckardt, Alexander Petutschnigg and Jan Tippner

Materials 2022, 15(9), 3299; https://doi.org/10.3390/ma15093299 - 4 May 2022

Cited by 6 | Viewed by 3009

Rising energy and raw material prices, dwindling resources, increased recycling, and the need for sustainable management have led to growth in the smart materials sector. In recent years, the importance and diversity of bio-based adhesives for industrial applications has grown steadily. This article [...] Read more.

Rising energy and raw material prices, dwindling resources, increased recycling, and the need for sustainable management have led to growth in the smart materials sector. In recent years, the importance and diversity of bio-based adhesives for industrial applications has grown steadily. This article focuses on the production and characterization of insulation panels consisting of peat moss and two bio-based adhesives. The panels were pressed with tannin and animal-based resins and compared to panels bonded with urea formaldehyde. The physical–mechanical properties, namely, thermal conductivity (TC), water vapor diffusion resistance, modulus of rupture (MOR), modulus of elasticity (MOE), internal bond (IB), compression resistance (CR), water absorption (WA) and thickness swelling (TS) were measured and analyzed. The results show that the insulation effectiveness and mechanical stability of moss panels bound with tannin and animal glue are comparable to standard adhesives used in the composite industry. Full article

(This article belongs to the Special Issue Smart and Renewable Materials: Characterization, Manufacturing and Application)

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12 pages, 2730 KiB

Open AccessArticle

Organosolv Lignin from European Tree Bark: Influence of Bark Pretreatment

by Jakub Grzybek, Thomas Sepperer, Alexander Petutschnigg and Thomas Schnabel

Materials 2021, 14(24), 7774; https://doi.org/10.3390/ma14247774 - 16 Dec 2021

Cited by 7 | Viewed by 2926

Abstract

As lignin is becoming more and more attractive to industry and the circular economy continues to grow, the utilization of a byproduct that, to date, has been underrated by the wood industry is investigated as an abundantly available source of lignin. Bark from [...] Read more.

As lignin is becoming more and more attractive to industry and the circular economy continues to grow, the utilization of a byproduct that, to date, has been underrated by the wood industry is investigated as an abundantly available source of lignin. Bark from spruce, larch and beech tress is extracted using the organosolv process with and without prior hot water extraction. The influence of the treatment on chemical properties of the lignin was determined by spectrophotometric, chromatographic, and vibrational spectroscopy. It was found that hot water extraction prior to organosolv extraction influences the chemical composition, antioxidative properties and molecular weight distribution of the obtained extracts. While hot water extracts are rich in flavonoids, organosolv fractions can contain high amounts of organic acids depending on whether they are from a hardwood or softwood source. This investigation lays the foundation for further research into the utilization of byproducts to generate high-value resources. Full article

(This article belongs to the Special Issue Smart and Renewable Materials: Characterization, Manufacturing and Application)

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16 pages, 3861 KiB

Open AccessArticle

Hyperelastic Material Parameter Determination and Numerical Study of TPU and PDMS Dampers

by Carina Emminger, Umut D. Çakmak, Rene Preuer, Ingrid Graz and Zoltán Major

Materials 2021, 14(24), 7639; https://doi.org/10.3390/ma14247639 - 11 Dec 2021

Cited by 15 | Viewed by 3791

Abstract

Dampers provide safety by controlling unwanted motion that is caused due to the conversion of mechanical work into another form of energy (e.g., heat). State-of-the-art materials are elastomers and include thermoplastic elastomers. For the polymer-appropriate replacement of multi-component shock absorbers comprising mounts, rods, [...] Read more.

Dampers provide safety by controlling unwanted motion that is caused due to the conversion of mechanical work into another form of energy (e.g., heat). State-of-the-art materials are elastomers and include thermoplastic elastomers. For the polymer-appropriate replacement of multi-component shock absorbers comprising mounts, rods, hydraulic fluids, pneumatic devices, or electro-magnetic devices, among others, in-depth insights into the mechanical characteristics of damper materials are required. The ultimate objective is to reduce complexity by utilizing inherent material damping rather than structural (multi-component) damping properties. The objective of this work was to compare the damping behavior of different elastomeric materials including thermoplastic poly(urethane) (TPU) and silicone rubber blends (mixtures of different poly(dimethylsiloxane) (PDMS)). Therefore, the materials were hyper- and viscoelastic characterized, a finite element calculation of a ball drop test was performed, and for validation, the rebound resilience was measured experimentally. The results revealed that the material parameter determination methodology is reliable, and the data that were applied for simulation led to realistic predictions. Interestingly, the rebound resilience of the mixture of soft and hard PDMS (50:50) wt% was the highest, and the lowest values were measured for TPU. Full article

(This article belongs to the Special Issue Smart and Renewable Materials: Characterization, Manufacturing and Application)

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12 pages, 1398 KiB

Open AccessArticle

Production and Physical–Mechanical Characterization of Peat Moss (Sphagnum) Insulation Panels

by Günther Kain, Marco Morandini, Angela Stamminger, Thomas Granig, Eugenia Mariana Tudor, Thomas Schnabel and Alexander Petutschnigg

Materials 2021, 14(21), 6601; https://doi.org/10.3390/ma14216601 - 2 Nov 2021

Cited by 8 | Viewed by 2866

Abstract

Peat moss (sphagnum) is a commonly used sealant, fill, and insulation material in the past. During the efforts to rewet drained moors due to ecological considerations, the technical use of peat moss (sphagnum farming) again became the focus of attention. In the framework [...] Read more.

Peat moss (sphagnum) is a commonly used sealant, fill, and insulation material in the past. During the efforts to rewet drained moors due to ecological considerations, the technical use of peat moss (sphagnum farming) again became the focus of attention. In the framework of this investigation, insulation panels consisting of peat moss, bound with urea formaldehyde, were produced. Panels manufactured in a wet process and mats bound with textiles were also fabricated. The specimens’ thermal conductivity, water vapor diffusion resistance, modulus of rupture, modulus of elasticity, internal bond, compression resistance, water absorption, and thickness swelling were measured. Physical–mechanical properties were adequate with the resin-bound panels, but not with wet process panels. Moss mats had good characteristics for cavity insulation purposes. The thermal conductivity of the moss panels and mats was found to be lowest with a density of 50 kg/m³, accounting for 0.04 W/m·K. The results show that peat moss is a promising resource for production insulation panels, because their thermal conductivity and mechanical stability are comparable to other insulation materials. Full article

(This article belongs to the Special Issue Smart and Renewable Materials: Characterization, Manufacturing and Application)

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11 pages, 1889 KiB

Open AccessArticle

The Mechanical Performance of Re-Bonded and Healed Adhesive Joints Activable through Induction Heating Systems

by Raffaele Ciardiello

Materials 2021, 14(21), 6351; https://doi.org/10.3390/ma14216351 - 24 Oct 2021

Cited by 9 | Viewed by 2067

Abstract

This work aims to study the healing potential properties of a reversible thermoplastic adhesive. The adhesive is activable by using induction heating systems that can induce thermal heat in the particles throughout the electromagnetic field so they can melt the adhesive for bonding [...] Read more.

This work aims to study the healing potential properties of a reversible thermoplastic adhesive. The adhesive is activable by using induction heating systems that can induce thermal heat in the particles throughout the electromagnetic field so they can melt the adhesive for bonding or separation procedures. The healing procedure consists of damaging single lap joint (SLJ) specimens with quasi-static and fatigue tests and then using an inductor to generate an electromagnetic field able to heat the adhesive to its melting point in order to heal the damaged SLJ specimens. SLJ tests were performed on damaged and healed specimens to assess, respectively, the residual mechanical properties of the damaged specimens and the mechanical properties after healing. SLJ tests showed that the healing procedure can completely recover the joint stiffness of the damaged adhesive joints, a huge part of the maximum shear strength and the SLJ absorbed energy. This work shows also the possibility of re-bonding completely failed or separated SLJs by using the same procedure. The mechanical properties of SLJs after healing and re-bonding are compared to the SLJ compared on virgin specimens to assess the recovered mechanical properties. Full article

(This article belongs to the Special Issue Smart and Renewable Materials: Characterization, Manufacturing and Application)

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13 pages, 1845 KiB

Open AccessArticle

Biopolymer Degradation Analysis: Accelerated Life Testing Study to Characterize Polylactic Acid Durability

by Elias H. Arias-Nava, B. Patrick Sullivan and Delia J. Valles-Rosales

Materials 2021, 14(19), 5730; https://doi.org/10.3390/ma14195730 - 30 Sep 2021

Cited by 8 | Viewed by 2133

Abstract

While the degradation of Polylactic Acid (PLA) has been studied for several years, results regarding the mechanism for determining degradation are not completely understood. Through accelerated degradation testing, data can be extrapolated and modeled to test parameters such as temperature, voltage, time, and [...] Read more.

While the degradation of Polylactic Acid (PLA) has been studied for several years, results regarding the mechanism for determining degradation are not completely understood. Through accelerated degradation testing, data can be extrapolated and modeled to test parameters such as temperature, voltage, time, and humidity. Accelerated lifetime testing is used as an alternative to experimentation under normal conditions. The methodology to create this model consisted of fabricating series of ASTM specimens using extrusion and injection molding. These specimens were tested through accelerated degradation; tensile and flexural testing were conducted at different points of time. Nonparametric inference tests for multivariate data are presented. The results indicate that the effect of the independent variable or treatment effect (time) is highly significant. This research intends to provide a better understanding of biopolymer degradation. The findings indicated that the proposed statistical models can be used as a tool for characterization of the material regarding the durability of the biopolymer as an engineering material. Having multiple models, one for each individual accelerating variable, allow deciding which parameter is critical in the characterization of the material. Full article

(This article belongs to the Special Issue Smart and Renewable Materials: Characterization, Manufacturing and Application)

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18 pages, 6308 KiB

Open AccessArticle

Basalt/Glass Fiber Polypropylene Hybrid Composites: Mechanical Properties at Different Temperatures and under Cyclic Loading and Micromechanical Modelling

by Anna Kufel, Slawomir Para and Stanisław Kuciel

Materials 2021, 14(19), 5574; https://doi.org/10.3390/ma14195574 - 25 Sep 2021

Cited by 15 | Viewed by 3057

Abstract

Basalt/glass fiber polypropylene hybrid composites were developed as subjects of investigation, with the aim to characterize their properties. An injection molding machine was used to produce the test samples. The following three different tests, at various specimen temperatures, were conducted: tensile test, three-point [...] Read more.

Basalt/glass fiber polypropylene hybrid composites were developed as subjects of investigation, with the aim to characterize their properties. An injection molding machine was used to produce the test samples. The following three different tests, at various specimen temperatures, were conducted: tensile test, three-point flexural test, and Charpy impact test. To determine fatigue behavior, the samples were uniaxially loaded and unloaded. Mechanical hysteresis loops were recorded and the dissipation energy of each loop was calculated. To determine the adhesion and dispersion between the fibers and the matrix, the fractured surfaces of the various specimens, after the tensile test, were investigated using a scanning electron microscope. The results show that the production of a composite with both basalt and glass fibers, in a polypropylene matrix with maleic anhydride-grafted polypropylene, can be successfully achieved. The addition of the two types of fibers increased the tensile strength by 306% and the tensile modulus by 333% for a composition, with 20% by weight, of fibers. The material properties were estimated with the help of a simulation software, and validated with a FEA. A satisfactory correlation between the simulation and measurement data was achieved. The error lays in a range of 2% between the maximum stress values. At a lower strain (up to 0.02), the stress values are very well matched. Full article

(This article belongs to the Special Issue Smart and Renewable Materials: Characterization, Manufacturing and Application)

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17 pages, 3693 KiB

Open AccessArticle

A Systematic Study on Bio-Based Hybrid Aerogels Made of Tannin and Silica

by Ann-Kathrin Koopmann, Wim J. Malfait, Thomas Sepperer and Nicola Huesing

Materials 2021, 14(18), 5231; https://doi.org/10.3390/ma14185231 - 11 Sep 2021

Cited by 3 | Viewed by 2150

Abstract

Tannin-silica hybrid materials are expected to feature excellent mechanic-chemical stability, large surface areas, high porosity and possess, after carbothermal reduction, high thermal stability as well as high thermal conductivity. Typically, a commercially available tetraethoxysilane is used, but in this study, a more sustainable [...] Read more.

Tannin-silica hybrid materials are expected to feature excellent mechanic-chemical stability, large surface areas, high porosity and possess, after carbothermal reduction, high thermal stability as well as high thermal conductivity. Typically, a commercially available tetraethoxysilane is used, but in this study, a more sustainable route was developed by using a glycol-based silica precursor, tetrakis(2-hydroxyethyl)orthosilicate (EGMS), which is highly water-soluble. In order to produce highly porous, homogeneous hybrid tannin-silica aerogels in a one-pot approach, a suitable crosslinker has to be used. It was found that an aldehyde-functionalized silane (triethoxysilylbutyraldehyde) enables the covalent bonding of tannin and silica. Solely by altering the processing parameters, distinctly different tannin-silica hybrid material properties could be achieved. In particular, the amount of crosslinker is a significant factor with respect to altering the materials’ properties, e.g., the specific surface area. Notably, 5 wt% of crosslinker presents an optimal percentage to obtain a sustainable tannin-silica hybrid system with high specific surface areas of roughly 800–900 m² g⁻¹ as well as a high mesopore volume. The synthesized tannin-silica hybrid aerogels permit the usage as green precursor for silicon carbide materials. Full article

(This article belongs to the Special Issue Smart and Renewable Materials: Characterization, Manufacturing and Application)

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