Thermomechanical Characterization Research Articles

Advancing energy efficiency: thermomechanical characterization of plastic-infused concrete for sustainable building solutions

Advancing energy efficiency: thermomechanical characterization of plastic-infused concrete for sustainable building solutions

Extrusion Parameters Optimization and Mechanical Properties of Bio-Polyamide 11-Based Biocomposites Reinforced with Short Basalt Fibers.

The increasing demand for sustainable materials in high-value applications, particularly in the automotive industry, has prompted the development of biocomposites based on renewable or recyclable matrices and natural fibers as reinforcements. In this context, this paper aimed to produce composites with improved mechanical and thermal properties (tensile, flexural, and heat deflection temperature) through an optimized process pathway using a biobased polyamide reinforced with short basalt fibers. This study emphasizes the critical impact of fiber length, matrix adhesion, and the variation in matrix properties with increasing fiber content. These factors influence the properties of short-fiber composites produced via primary processing using extrusion and shaped through injection molding. The aim of this work was to optimize extrusion conditions using a 1D simulation software to minimize excessive fiber fragmentation during the extrusion process. The predictive model's capacity to forecast fiber degradation and the extent of additional fiber breakage during extrusion was evaluated. Furthermore, the impact of injection molding on these conditions was investigated. Moreover, a comprehensive thermomechanical characterization of the composites, comprising 10%, 20%, and 30% fiber content, was carried out, focusing on the correlation with morphology and processing using SEM and micro-CT analyses. In particular, how the extrusion process parameters adopted can influence fiber breakage and how injection molding can influence the fiber orientation were investigated, highlighting their influence in determining the final mechanical properties of short fiber composites. By optimizing the process parameters, an increment with respect to bio-PA11 in the tensile strength of 38%, stiffness of 140%, and HDT of 77% compared to the matrix were obtained.

3DP for sustainable built environment – Synthesis and thermomechanical characterization of composite materials based on local soil and date palm fiber waste

There is an increasing demand for sustainable construction materials to address the challenges posed by the environmental impact of the built environment (BE), which is driven by climate change, population growth, and urbanization. Conventional construction materials like cement contribute significantly to carbon emissions during production, transport, use, and disposal phases, and their poor thermal conductivity hinders efforts to maintain comfortable indoor environments. To address these challenges, there is an urgent need for innovative, locally sourced thermal insulation materials specifically designed for regions with extreme climates and high energy demands to maintain building comfort. This research explores synthesizing novel, environmentally friendly building materials using locally sourced date palm fiber waste and clay. The study also investigates the developed material's 3D printing (3DP) capabilities and optimizes its printing parameters with lab-scale prototypes. Additionally, thermo-mechanical characterization is conducted to assess its suitability for built environment applications. Different concentrations, from 1 to 5 wt% of date palm fiber to clay ratio (Dpf/C), were studied regarding microstructural, thermal, and mechanical properties, dimensional accuracy, and feasibility for 3DP of BE structures. Results demonstrated a significant reduction in thermal conductivity by 73%, achieving 0.244 W/mK, and an increase in compressive strength by 106%, reaching 10.9 MPa at 5 wt% Dpf/C. The promising thermomechanical properties of these composites and their suitability for 3DP support their use in real-world applications in the future's sustainable built environment. This scalable methodology can be adapted to regions with similar sustainable local and waste resources, advancing the circular economy.

Thermomechanical and Viscoelastic Characterization of Continuous GF/PETG Tape for Extreme Environment Applications

The thermomechanical and viscoelastic properties of a glass fiber polyethylene terephthalate glycol (GF/PETG) continuous unidirectional (UD) tape were investigated using differential scanning calorimetry (DSC), thermomechanical analysis (TMA), and dynamic mechanical analysis (DMA). This study identified five operational conditions based on the Army Regulation 70-38 Standard. The DSC results revealed a glass transition temperature of 78.0 ± 0.3 °C, guiding the selection of temperatures for TMA and DMA tests. TMA provided the coefficient of thermal expansion in three principal directions, consistent with known values for PETG and GF materials. DMA tests, including strain sweep, temperature ramp, frequency sweep, creep, and stress relaxation, defined the material’s linear viscoelastic region and temperature-dependent properties. The frequency sweep indicated an increased modulus with rising frequency, identifying several natural frequency modes. Creep and stress relaxation tests showed time-dependent behavior, with strain increasing under higher loads and stress decreasing over time for all tested input values. Viscoelastic models fitted to the data yielded R2 values of 0.99, demonstrating good agreement. The study successfully measured thermomechanical and viscoelastic properties across various conditions, providing insights into how temperature influences the material’s mechanical response under extreme conditions.

Thermomechanical characterisation and plane stress linear viscoelastic modelling of ethylene-tetra-fluoroethylene foils

Ethylene-tetra-fluoroethylene (ETFE) is a polymer employed in tension membrane structures with mechanical properties that strongly depend on time and temperature effects. A comprehensive understanding of the mutual influence of these variables and a unified viscoelastic constitutive model design can enable wider exploitation of ETFE in sustainable lightweight construction. This study presents a thermomechanical characterisation of ETFE foils through quasi-static tensile experiments spanning two orders of magnitude of strain rates, creep, relaxation, shear and dynamic cyclic tests in a wide range of temperatures suitable for building applications, from −20∘ C\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$-20^{\\circ }\ ext{ C}$\\end{document} to 60∘ C\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$60^{\\circ }\ ext{ C}$\\end{document}. The experimental results in different material orientations are used to identify the limits of the linear viscoelastic domain, define the direction-dependent creep compliance master curves and calibrate the parameters of a plane stress orthotropic linear viscoelastic model, employing the Boltzmann superposition and the time-temperature superposition principles. The model has been numerically implemented using a recursive integration algorithm and its code is provided open source. A validation on independently acquired data shows the accuracy of the constitutive model in predicting ETFE behaviour within the linear viscoelastic regime usually adopted during structural design, with excellent extrapolation capabilities outside the range of the calibration data.

A study of dynamic recovery and recrystallisation mechanisms in aluminium alloy AA7050 at different thermomechanical processing conditions

The effects of hot deformation strain rates and temperatures on aluminium alloys' dynamic recovery and recrystallisation mechanisms have been widely discussed in the literature. However, their influence remains controversial due to a need for comprehensive and detailed thermomechanical testing and characterisation data across a wide range of hot deformation conditions. In this study, hot compression tests of AA7050 were conducted at strain rates of 0.0005–5 s−1 and temperatures of 380–460 °C. The geometrically necessary dislocation (GND), low-angle grain boundary (LAGB) and high-angle grain boundary (HAGB) were acquired by the latest high angular resolution, high-speed EBSD detector (OI Symmetry 2), and their underlying mechanisms were analysed in relation to Zener-Hollomon parameter (Z). It was found that within the tested range of the hot compression condition (ln (Z) between 20.23 and 29.45), continuous dynamic recrystallisation (CDRX) predominates at lower ln (Z) values with its activity being initially increased and then decreased as ln (Z) rises, while discontinuous dynamic recrystallisation (DDRX) becomes dominant at higher ln (Z) levels. This transition of the dominant mechanism is intriguingly reflected in the evolution of HAGB length, which increases, then decreases and finally increases again. The LAGB length shows a relatively linear relationship with ln (Z), and the average GND density exhibits a near-linear correlation until reaching a plateau. Based on the obtained results, the transformation of the dominant microstructural evolution mechanisms with increasing ln (Z) was clarified: from grain growth, to recovery, to CDRX, and then to DDRX, along with the quantitative trend of HAGB length per unit area. This transformation mechanism is believed to encompass the full range of material processing window, providing a basis for justifying the previous controversial proposition in literature and a guide for defining and fabricating microstructures in manufacturing applications.

Thermomechanical and damage characterisation of short glass fibre reinforced polyamide 6 and impact-modified polyamide 6 composites

Polyamide 6 and its composites are widely used in engineering applications that are exposed to high strain rate deformation. This paper investigates the thermomechanical properties of two polyamide 6 composites, both reinforced with 30 wt% short glass fibres, and one of which additionally contains an impact modifier, to provide an understanding of the mechanical response over a wide range of strain rates and temperatures. Compression experiments were performed at rates between 2 and 3000 s−1, with high speed optical and infrared cameras to aid interpretation of the rate-dependent failure arising from the formation of adiabatic shear bands. Further high strain rate experiments were performed with ultra-fast X-ray phase-contrast imaging to provide in-situ internal damage evaluation. These data will improve the utilization of these composites and aid in development of advanced thermomechanical models.

Thermo-mechanical characterization of pinless friction stir welding in AA6060-T4 thin sheets

Friction Stir Welding (FSW) is a solid-state welding method, offering superior weld quality for aluminum alloys. Despite its advantages, the thermo-mechanical characteristics of pinless FSW, especially for AA6060-T4 aluminum thin sheets, remain underexplored. This study aims to fill this gap by examining the effects of different welding parameters on the mechanical properties and thermal distribution in pinless FSW of 2 mm AA6060-T4 sheets. Experimental welding tests were conducted using high alloy steel tools and a modified milling machine, with variations in rotation and feed rates. The results show that higher rotation speeds correlate with lower maximum temperatures, and increased feed rates further reduce temperatures. Optimal welding parameters achieved efficiency coefficients as high as 84%. Microhardness profiles indicated minimum hardness in the Thermo-Mechanically Affected Zone (TMAZ) and a significant increase on the advancing side. These findings enhance the understanding of pinless FSW, emphasizing the interaction between welding parameters and mechanical properties. This research advances the application of AA6060-T4 in various industrial sectors by providing valuable insights into optimizing weld quality and mechanical performance.

Pre-structural patterning approach for enhancing flow characteristics of B-stage film-type epoxy molding compound

Epoxy molding compound (EMC) compositions of silica powder and epoxy matrix have been utilized as encapsulation for semiconductor packaging over the past decades. Among various forms of EMC, film-type EMC offers untapped potential. Utilizing EMC film as an encapsulation material allows larger and more uniform encapsulation behavior especially for panel-level and wafer-level packaging applications. In material aspects, as increases silica contents in EMC film, it can encounter a trade-off relationship between the coefficient of thermal expansion (CTE) and the material's viscosity. As silica content increases, the CTE tends to decrease, which enhances warpage behavior. However, viscosity also tends to increase, which reduces flowability. To overcome these tradeoff relationships, in our study, we have demonstrated a pre-structural patterning approach to enhance flowability of B-stage EMC film without changing the raw compositions of material. By doing that, we can suppose increased flowability of film while having similar thermomechanical properties. For patterning while maintaining B-stage, patterned protection film was fabricated using a brass-based metallic mold and a PDMS/PUA-based soft mold. Subsequently, pre-structural patterned EMC was fabricated by transferring the patterned protection film onto a B-stage EMC film using a laminator. The effectiveness of patterning on EMC film was investigated in both numerical and experimental molding analysis according to rheological, chemical, and thermomechanical characterization. The pre-structural patterning approach demonstrated enhanced flow characteristics via a shortened flow path despite the increased viscosity caused by higher silica content.

Active interlocking metasurfaces enabled by shape memory alloys

Interlocking metasurfaces (ILMs) are a newly developed joining technology that relies on arrays of interlocking features that transmit force and constrain motion between adjoining bodies in one or more directions. This study explores harnessing the shape memory effect (SME) in Nickel-Titanium shape memory alloys (NiTi SMAs) in structures fabricated using additive manufacturing (AM) to advance the development of active ILMs by creating unit cells that open or close at specific temperatures. The study encompasses designing and fabricating two distinct interlocking array configurations using near-equiatomic NiTi powder and the laser powder bed fusion (L-PBF) AM technique, following a previously developed AM process optimization framework to manufacture defect-free parts. To guide the design process, finite element analysis (FEA) was employed to predict strain values during engage-disengage cycles. The martensitic transformation characteristics of the ILMs were characterized. Thermomechanical testing revealed that the ILMs demonstrate high locking force once engaged, coupled with complete shape recovery and good cyclic stability. Digital image correlation (DIC) was also employed to validate the FEA predictions during the engage-disengage cycles. The results indicate that NiTi SMA-based ILMs can be designed and fabricated into complex shapes using L-PBF. By leveraging the SME, the functionality of an ILM can be improved upon. The combination of computational modeling, additive manufacturing, and thermomechanical and physical property characterization provides a framework for designing future ILMs out of active materials.

Thermomechanical Material Characterization of Polyethylene Terephthalate Glycol with 30% Carbon Fiber for Large-Format Additive Manufacturing of Polymer Structures.

Large-format additive manufacturing (LFAM) is used to print large-scale polymer structures. Understanding the thermal and mechanical properties of polymers suitable for large-scale extrusion is needed for design and production capabilities. An in-house-built LFAM printer was used to print polyethylene terephthalate glycol with 30% carbon fiber (PETG CF30%) samples for thermomechanical characterization. Thermogravimetric analysis (TGA) shows that the samples were 30% carbon fiber by weight. X-ray microscopy (XRM) and porosity studies find 25% voids/volume for undried material and 1.63% voids/volume for dry material. Differential scanning calorimetry (DSC) shows a glass transition temperature (Tg) of 66 °C, while dynamic mechanical analysis (DMA) found Tg as 82 °C. The rheology indicated that PETG CF30% is a good printing material at 220-250 °C. Bending experiments show an average of 48.5 MPa for flexure strength, while tensile experiments found an average tensile strength of 25.0 MPa at room temperature. Comparison with 3D-printed PLA and PETG from the literature demonstrated that LFAM-printed PETG CF30% had a comparative high Young's modulus and had similar tensile strength. For design purposes, prints from LFAM should consider both material choice and print parameters, especially when considering large layer heights.

Digital Light Processing to Afford High Resolution and Degradable CO2‐Derived Copolymer Elastomers

AbstractVat photopolymerization 3D printing has proven very successful for the rapid additive manufacturing (AM) of polymeric parts at high resolution. However, the range of materials that can be printed and their resulting properties remains narrow. Herein, we report the successful AM of a series of poly(carbonate‐b‐ester‐b‐carbonate) elastomers, derived from carbon dioxide and bio‐derived ϵ‐decalactone. By employing a highly active and selective Co(II)Mg(II) polymerization catalyst, an ABA triblock copolymer (Mn=6.3 kg mol−1, ÐM=1.26) was synthesized, formulated into resins which were 3D printed using digital light processing (DLP) and a thiol‐ene‐based crosslinking system. A series of elastomeric and degradable thermosets were produced, with varying thiol cross‐linker length and poly(ethylene glycol) content, to produce complex triply periodic geometries at high resolution. Thermomechanical characterization of the materials reveals printing‐induced microphase separation and tunable hydrophilicity. These findings highlight how utilizing DLP can produce sustainable materials from low molar mass polyols quickly and at high resolution. The 3D printing of these functional materials may help to expedite the production of sustainable plastics and elastomers with potential to replace conventional petrochemical‐based options.

Digital Light Processing to Afford High Resolution and Degradable CO2-Derived Copolymer Elastomers.

Vat photopolymerization 3D printing has proven very successful for the rapid additive manufacturing (AM) of polymeric parts at high resolution. However, the range of materials that can be printed and their resulting properties remains narrow. Herein, we report the successful AM of a series of poly(carbonate-b-ester-b-carbonate) elastomers, derived from carbon dioxide and bio-derived ϵ-decalactone. By employing a highly active and selective Co(II)Mg(II) polymerization catalyst, an ABA triblock copolymer (Mn=6.3 kg mol-1, ÐM=1.26) was synthesized, formulated into resins which were 3D printed using digital light processing (DLP) and a thiol-ene-based crosslinking system. A series of elastomeric and degradable thermosets were produced, with varying thiol cross-linker length and poly(ethylene glycol) content, to produce complex triply periodic geometries at high resolution. Thermomechanical characterization of the materials reveals printing-induced microphase separation and tunable hydrophilicity. These findings highlight how utilizing DLP can produce sustainable materials from low molar mass polyols quickly and at high resolution. The 3D printing of these functional materials may help to expedite the production of sustainable plastics and elastomers with potential to replace conventional petrochemical-based options.

Birefringent optical fibers to decouple thermo-mechanical effects on FBG sensors

Optical fiber Bragg (FBG) sensors are gaining importance in structural health monitoring (SHM) systems due to their compact size and ability to be embedded into the lamination sequences of composite material elements. A significant challenge, widely discussed in the literature, concerns the decoupling of thermomechanical measurements made through these sensors. This work aims to solve this problem using birefringent optical fibers instead of conventional ones. The distinctive characteristics of birefringent fibers allow an FBG sensor, written in such fibers, to present not a single peak but two distinct peaks, each with different responses to changes in strain and temperature. This is due to the different refractive index distribution in the fiber core section, which allows for two axes on which the light signal propagates at different speeds. This property offers a significant advantage: by having two independent equations associated with the two peaks, it is possible to decouple the thermomechanical measurements using only the fiber itself, without the need to introduce additional components to achieve mechanical decoupling (capillaries with through or interrupted fiber). This would ensure that strain and temperature are measured at the same point. In the first phase of the work, an FBG sensor on a birefringent fiber was characterized and subsequently calibrated. Therefore, a dedicated experimental set-up was created to conduct thermal, mechanical, and thermomechanical characterization tests, in order to verify the feasibility and effectiveness of decoupling. In a second step, such sensor was embedded within a sample of composite material (unidirectional glass fibers), which was subsequently subjected to the same characterization tests conducted on the single fiber. The results highlight the ability of this new transducer to decouple the thermal effect from the mechanical effect, allowing this new technology to overcome the problems of FBG sensors made of standard fibers.

Physical and thermomechanical characterization of unidirectional Helicteres isora fiber-reinforced polylactic acid bio-composites

Identifying novel cellulose fiber bio-composites has become a vital initiative in the exploration of sustainable materials due to increased global concern for the environment. This growing focus on eco-friendly materials has gathered significant attention in recent years. The current investigation deals with one such material, Helicteres isora reinforced Polylactic acid composites. Surface chemical treatment of fiber is one of the most effective methods to modify the hydrophilic fiber to increase its compatibility with the polymer matrix. Sodium hydroxide was used as a pre-treatment chemical to remove any impurities from the fiber surface. Pre-treated fibers were treated with Methacryl silane and Potassium permanganate solution to chemically modify the fiber surface. Density, void content and water absorption behavior of the composites were analyzed as per the standard procedure. Tensile and flexural tests were conducted to evaluate the mechanical strength, modulus, and flexibility of the unidirectional composites. Thermogravimetric and differential thermal analyses were performed to investigate the thermal stability, melting behavior and degradation profiles of prepared composites. A study of failure mechanisms and morphology of the fractured surface through photographs and SEM images revealed fiber splitting and delamination as the dominant reasons behind the failure of composites under tensile loading. Silane-treated Helicteres isora fiber-reinforced Polylactic acid composite exhibited lower water absorption and higher tensile strength than its counterparts. Untreated fiber composite showed maximum flexural strength among the tested composites. By collectively evaluating the results of the tests and properties of the composites, silane-treated fiber-reinforced Polylactic acid composites stands out as the most favorable choice.

Characterization and modeling of an epoxy vitrimer based on disulfide exchange for wet filament winding applications

AbstractThe present paper investigates the suitability of a vitrimeric epoxy resin for processing in the wet filament winding (WFW) process to manufacture fiber‐reinforced polymers (FRP). Comprehensive material characterization of a commercially available epoxy and vitrimeric resin based on disulfide exchange is carried out, and the processing in WFW is evaluated by analyzing thermomechanical, rheological, thermochemical properties, and chemical shrinkage. The direct comparison of a vitrimer and an established epoxy resin permits an indication of the processability and necessary adjustments in WFW. Based on the implications of modeling, we demonstrate the processing of the vitrimeric resin in the WFW process by increasing the resin bath temperatures. The vitrimer's and conventional resin's elastic modulus development and compression behavior were similar, highlighting the vitrimeric resin's potential. Further, the results confirm that established characterization and modeling routines can be transferred to vitrimeric resins and, therefore, path the way toward advanced process simulation of vitrimeric resin's processing. For this, the present publication gives essential advice for setting up testing schedules for characterizing epoxy vitrimers' processing behavior and their appropriate modeling. The present work underlines the potential of applying commercially available dynamic hardeners to manufacture recyclable and malleable FRP in established processes.Highlights Material characterization and modeling of wet filament winding process. Wet filament winding of epoxy vitrimers. Thermomechanical and chemical shrinkage characterization of epoxy vitrimers. Rheological and kinetic modeling of epoxy vitrimer.

DLP 3D Printing of Levoglucosenone-Based Monomers: Exploiting Thiol-ene Chemistry for Bio-Based Polymeric Resins.

Additive manufacturing (AM) is a well-established technique that allows for the development of complex geometries and structures with multiple applications. While considered a more environmentally-friendly method than traditional manufacturing, a significant challenge lies in the availability and ease of synthesis of bio-based alternative resins. In our endeavor to valorize biomass, this work proposes the synthesis of new α,ω-dienes derived from cellulose-derived levoglucosenone (LGO). These dienes are not only straightforward to synthesize but also offer a tunable synthesis approach. Specifically, LGO is first converted into diol precursor, which is subsequently esterified using various carboxylic acids (in this case, 3-butenoic, and 4-pentenoic acids) through a straightforward chemical pathway. The resulting monomers were then employed in UV-activated thiol-ene chemistry for digital light process (DLP). A comprehensive study of the UV-curing process was carried out by Design of Experiment (DoE) to evaluate the influence of light intensity and photoinitiator to find the optimal curing conditions. Subsequently, a thorough thermo-mechanical characterization highlighted the influence of the chemical structure on material properties. 3D printing was performed, enabling the fabrication of complex and self-stain structures with remarkable accuracy and precision. Lastly, a chemical degradation study revealed the potential for end-of-use recycling of the bio-based thermosets.

Thermal, dosimetric and thermo-mechanical characterization of ABS and PLA polymer materials via plastic injection molding for innovative bolus materials in radiotherapy applications

The impact of radiation on polymer materials, and consequently on their mechanical and physical properties, is a burgeoning field of research. This research assesses the dosimetric, mechanical, and thermal characteristics of Acrylonitrile Butadiene Styrene (ABS) and Polylactic Acid (PLA) materials developed through plastic injection molding as possible alternatives to commercial bolus used in radiotherapy. The materials were thoroughly compared with the commercial bolus material, EXAFLEX, by various tests such as Hounsfield Unit (HU) Analysis, Radiation Transmittance, Thermogravimetric Analysis (TGA), Thermomechanical Analysis (TMA), and Fourier Transform Infrared Spectroscopy (FTIR). The research indicates that ABS and PLA materials have similar radiological qualities to EXAFLEX, showing constant surface and accumulation area doses. Minor differences are seen deeper inside the phantom, indicating a stable tissue equivalency. ABS demonstrated strong resistance to radiation-induced chemical modifications, but PLA exhibited susceptibility to molecular changes. The TMA findings showed that radiation caused a decrease in softening temperatures and an increase in the coefficient of thermal expansion for both ABS and PLA, indicating changes in their thermal stability and mechanical characteristics after irradiation. The study highlights the potential of ABS and PLA materials made through plastic injection molding as efficient and safety substitutes for commercial bolus materials, particularly for large area irradiation. This requires more research into their clinical uses and consequences.

Influence of Extrusion Screw Speed and CNT Concentration on the Mechanical and EMI Properties of PC/ABS Based Nanocomposites.

This study investigates the effect of extrusion screw speed and carbon nanotube (CNT) concentration on the thermal, mechanical, and electromagnetic interference shielding effectiveness (EMI SE) properties of Polycarbonate (PC)/acrylonitrile-butadiene-styrene (ABS) and its polymer nanocomposites (PNCs) by means of design of experiments (DoE) approach. A masterbatch method was employed to obtain the best dispersion of the CNTs throughout the polymer matrix. This study evaluates the thermo-mechanical characterisation of the polymers and PNCs at varying screw speeds to assess filler matrix bonding. The results highlight that CNT concentration has a significant effect on all mechanical properties, while screw speed only affects the Charpy impact strength and flexural properties of the samples. Compounding at 200 rpm has the best flexural and tensile strength, which is attributed to the best filler matrix bonding (highest storage modulus) of the PNCs. The best EMI SE results were obtained at 10 wt.% CNTs. This research contributes valuable insights into the effect of CNT concentration and extrusion screw speed on the mechanical, thermal and EMI SE properties of PC/ABS and its PNCs.

Fabrication of geopolymer composites using egg-shell and fly-ash: Comparison between the strength and stability, physio-chemical and mechanical properties

Nowadays, the demand for developing new structural materials, particulate composites made from industrial waste has been preferred along with conventional fiber-reinforced composites. In this work, two new composites were fabricated by reinforcing flyash and eggshell separately in epoxy with equal volume fractions and were termed geopolymer composites. Further thermo-mechanical characterization of these fabricated geopolymer composites was carried out by conducting various mechanical, physical, chemical, and thermal testing methods. The results were compared with the outcomes of neat epoxy composites. It was demonstrated that eggshell-epoxy composites have 28.48 % and 1.5 % more tensile strength than neat epoxy and flyash-epoxy composites. The flexural strength and hardness in a similar fashion were observed as increased by 31.7 %, 7.37 %, and 29.45 %, 15.6 % over neat epoxy and flyash-epoxy composites. The composites were crystalline confirmed from the XRD analysis. In contrast to the above, the thermal conductivity and thermal stability of flyash-epoxy composites were found superior though eggshell-epoxy composite visualized higher stability at the initial stage of thermal degradation. Further, the change of thermal conductivity of these materials with a temperature change was investigated by finite element modeling in MATLAB using the PDE toolbox. It was examined that thermal conductivity increases non-linearly with the increase in temperature up to 700 °C and then follows a uniform trend on further increase.