Journal of Composites Science

19 pages, 11136 KiB

Open AccessArticle

Determination and Validation of Residual Stresses in CFRP/Metal Hybrid Components Using the Incremental Hole Drilling Method

by Tao Wu, Steffen R. Tinkloh, Thomas Tröster, Wolfgang Zinn and Thomas Niendorf

J. Compos. Sci. 2020, 4(3), 143; https://doi.org/10.3390/jcs4030143 - 21 Sep 2020

Cited by 14 | Viewed by 3562

Abstract

Lightweight materials contribute to an efficient decrease in fuel consumption in the automotive and aircraft industries. Hybrid components made of metal and carbon fiber-reinforced plastics (CFRP) have a high potential in lightweight applications due to their high strength-to-weight ratio. For cost-effective processing of [...] Read more.

Lightweight materials contribute to an efficient decrease in fuel consumption in the automotive and aircraft industries. Hybrid components made of metal and carbon fiber-reinforced plastics (CFRP) have a high potential in lightweight applications due to their high strength-to-weight ratio. For cost-effective processing of hybrid materials, advanced manufacturing processes such as the prepreg-press-technology have been developed, in which the bonding between a metallic component and a fiber compound is exclusively realized in the forming process. However, upon processing of these hybrid components at elevated temperature, the difference in thermal expansion coefficients of the two materials leads to the formation of tensile residual stresses upon cooling. It is well known that these tensile residual stresses can be detrimentally effective with respect to the durability of a hybrid component. The objective of this work is to accurately measure and analyze residual stresses in hybrid components made of unidirectional CFRP and steel through the incremental hole drilling method. Within this study, the evaluation formalism for orthotropic materials is employed for measuring non-uniform residual stresses in hybrid materials. In order to improve the measurement accuracy, a customized strain gauge with eight grids is employed and a drilling increment size of only 20 µm is utilized. The influence of the angle between the strain gauge rosette and the fiber direction on the evaluation of the residual stresses is investigated. In order to evaluate the reliability of the results determined, a bending test applying a well-defined load is carried out. By direct comparison of the experimentally determined stresses and stress values calculated by the finite element method, the applicability of the hole drilling method for robust determination of residual stresses in CFRP/metal hybrid components is finally validated. Full article

(This article belongs to the Special Issue Metal Composites)

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15 pages, 2765 KiB

Open AccessArticle

Steel-Reinforced Polymers and Steel-Reinforced Composite Mortars for Structural Applications—An Overview

by Rafał Krzywoń

J. Compos. Sci. 2020, 4(3), 142; https://doi.org/10.3390/jcs4030142 - 20 Sep 2020

Cited by 3 | Viewed by 3326

Abstract

Bonding of external reinforcement is currently the simplest, fastest, and most popular method of strengthening concrete and masonry structures. Glass and carbon organic fibers are the dominant materials used, but alternatives also include high-strength steel wires. The mechanical properties of such steel are [...] Read more.

Bonding of external reinforcement is currently the simplest, fastest, and most popular method of strengthening concrete and masonry structures. Glass and carbon organic fibers are the dominant materials used, but alternatives also include high-strength steel wires. The mechanical properties of such steel are comparable to those of carbon fiber. Due to their good compatibility with mortars, steel wires are particularly well suited to the revitalization of historic buildings. The manuscript provides an overview of research and experience in the use of steel-reinforced polymers (SRPs) and steel-reinforced composite mortars (SRCMs, also called steel-reinforced grout (SRG)) for structural strengthening. The examples described are for concrete beams, slabs and columns, walls, and masonry arches. The results of laboratory tests are discussed. The summary presents the advantages and disadvantages of composites based on ultra-high-strength steels compared with more popular carbon fiber composites. Full article

(This article belongs to the Special Issue Polymer Composites: Fabrication and Applications)

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22 pages, 4915 KiB

Open AccessArticle

Polarization Parameters and Scaling Matter—How Processing Environment and Shape Factor Influence Electroactive Nanocomposite Characteristics

by S. Banerjee and K. A. Cook-Chennault

J. Compos. Sci. 2020, 4(3), 141; https://doi.org/10.3390/jcs4030141 - 19 Sep 2020

Viewed by 2804

Abstract

Polymeric-ceramic smart nanocomposite piezoelectric and dielectric materials are of interest due to their superior mechanical flexibility and ability to leverage characteristics of constituent materials. A great deal of work has centered on development of processes for manufacturing 0–3 continuity composite piezoelectric materials that [...] Read more.

Polymeric-ceramic smart nanocomposite piezoelectric and dielectric materials are of interest due to their superior mechanical flexibility and ability to leverage characteristics of constituent materials. A great deal of work has centered on development of processes for manufacturing 0–3 continuity composite piezoelectric materials that vary in scale ranging from bulk, thick and thin film to nanostructured films. Less is known about how material scaling effects the effectiveness of polarization and electromechanical properties. This study elucidates how polarization parameters: contact versus corona, temperature and electrical voltage field influence the piezoelectric and dielectric properties of samples as a function of their shape factor, i.e., bulk versus thick film. Bulk and thick film samples were prepared via sol gel/cast-mold and sol gel/spin coat deposition, for fabrication of bulk and thick films, respectively. It was found that corona polarization was more effective for both bulk and thick film processes and that polarization temperature produced higher normalized changes in samples. Although higher electric field voltages could be achieved with thicker samples, film samples responded the most to coupled increases in temperature and electrical voltage than bulk samples. Full article

(This article belongs to the Special Issue Composite Nanostructures for Energy and Environment Applications)

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25 pages, 3970 KiB

Open AccessArticle

Tensile and Compressive Behavior in the Experimental Tests for PLA Specimens Produced via Fused Deposition Modelling Technique

by Salvatore Brischetto and Roberto Torre

J. Compos. Sci. 2020, 4(3), 140; https://doi.org/10.3390/jcs4030140 - 18 Sep 2020

Cited by 53 | Viewed by 6630

Abstract

In this paper, polymeric specimens are produced via the Fused Deposition Modelling (FDM) technique. Then, experimental tensile and compression tests are conducted to evaluate the main mechanical properties of elements made of PolyLacticAcid (PLA) material. A standardized characterization test method for FDM 3D [...] Read more.

In this paper, polymeric specimens are produced via the Fused Deposition Modelling (FDM) technique. Then, experimental tensile and compression tests are conducted to evaluate the main mechanical properties of elements made of PolyLacticAcid (PLA) material. A standardized characterization test method for FDM 3D printed polymers has not been developed yet. For this reason, the ASTM D695 (usually employed for polymers produced via classical methods) has been here employed for FDM 3D printed polymers after opportune modifications suggested by appropriate experimental checks. A statistical analysis is performed on the geometrical data of the specimens to evaluate the machine process employed for the 3D printing. A capability analysis is also conducted on the mechanical properties (obtained from the experimental tests) in order to calculate acceptable limits useful for possible structural analyses. The Young modulus, the proportional limit and the maximum strength here defined for PLA specimens allow to confirm the different behavior of FDM printed PLA material in tensile and compressive state. These differences and the calculated acceptable limits for the found mechanical properties must be considered when this technology will be employed for the design of small structural objects made of PLA, as in the present study, or ABS (Acrilonitrile Butadiene Stirene). From the statistical and capability analysis, the employed printing process appears as quite stable and replicable. These types of research together with other similar ones that will be conducted in the future will allow to use polymeric materials and the FDM technique to produce small structural elements and also to carry out the appropriate verifications. Full article

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2020)

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11 pages, 4235 KiB

Open AccessArticle

The Mechanical and Material Designs of Composite Ju|’hoansi Arrowheads

by Courtney Archer, Iain Campbell, Fraser Cheyne, Amos Lim Jun Meng, Csongor Senanszky, Dimitrios Mamalis, Colin Robert and Parvez Alam

J. Compos. Sci. 2020, 4(3), 139; https://doi.org/10.3390/jcs4030139 - 18 Sep 2020

Cited by 4 | Viewed by 3386 | Correction

Abstract

In this paper, we elucidate the composite engineering design skills of the Kalahari Ju|’hoansi (San) people, developed over at least tens of thousands of years. In particular, we show that the mechanical and physical properties of materials used by the Ju|’hoansi in the [...] Read more.

In this paper, we elucidate the composite engineering design skills of the Kalahari Ju|’hoansi (San) people, developed over at least tens of thousands of years. In particular, we show that the mechanical and physical properties of materials used by the Ju|’hoansi in the design of arrowheads are intimately linked to their unique geometrical and composite designs. The Ju|’hoansi arrowheads have evolved to become complex engineered units with distinct function-specific purpose. We demonstrate herein that the geometrical designs of the arrowheads are optimised with respect to the material used. We furthermore verify the veracity of the Ju|’hoansi claim that their composite link-shafts are designed to break off leaving the arrowhead in the animal and the remaining parts of the arrow intact, reusable and easily retrievable. Full article

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2020)

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19 pages, 3522 KiB

Open AccessArticle

Adhesion of Multifunctional Substrates for Integrated Cure Monitoring Film Sensors to Carbon Fiber Reinforced Polymers

by Alexander Kyriazis, Kais Asali, Michael Sinapius, Korbinian Rager and Andreas Dietzel

J. Compos. Sci. 2020, 4(3), 138; https://doi.org/10.3390/jcs4030138 - 17 Sep 2020

Cited by 8 | Viewed by 3015

Abstract

During fiber composite production, the quality of the manufactured parts can be assured by measuring the progress of the curing reaction. Dielectric film sensors are particularly suitable for this measurement task, as they can quantify the degree of curing very specifically and locally. [...] Read more.

During fiber composite production, the quality of the manufactured parts can be assured by measuring the progress of the curing reaction. Dielectric film sensors are particularly suitable for this measurement task, as they can quantify the degree of curing very specifically and locally. These sensors are usually manufactured on PI films, which can lead to delaminations after integration. Other authors report that this negative influence can be reduced by miniaturization and a suitable shaping of the sensors. This article pursues as an alternative, a novel approach to achieve a material closure instead of a geometrically generated form closure by choosing suitable thermoplastic materials. Thermoplastic films made of PEI, PES and PA6 are proposed as carrier substrates for thin film sensors. They are investigated with regard to their mechanical effects in FRP. The experiments show that the integration of PES and PEI in FRP has the best shear strength, but PA6 leads to a higher critical energy release rate during crack propagation in mode I. For PI, a locally strongly scattering critical energy release rate was observed. Neither in tensile nor in Compression After Impact (CAI) tests a significant influence of the films on these characteristic values could be proven. Full article

(This article belongs to the Special Issue Carbon Fiber Composites)

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18 pages, 4908 KiB

Open AccessArticle

Thermoplastic Polyurethane/Lead Zirconate Titanate/Carbon Nanotube Composites with Very High Dielectric Permittivity and Low Dielectric Loss

by Gayaneh Petrossian, Nahal Aliheidari and Amir Ameli

J. Compos. Sci. 2020, 4(3), 137; https://doi.org/10.3390/jcs4030137 - 17 Sep 2020

Cited by 14 | Viewed by 3376

Abstract

Ternary composites of flexible thermoplastic polyurethane (TPU), lead zirconate titanate (PZT), and multiwalled carbon nanotubes (MWCNTs) with very high dielectric permittivity (ε_r) and low dielectric loss (tan δ) are reported. To assess the evolution of dielectric properties with the interactions [...] Read more.

Ternary composites of flexible thermoplastic polyurethane (TPU), lead zirconate titanate (PZT), and multiwalled carbon nanotubes (MWCNTs) with very high dielectric permittivity (ε_r) and low dielectric loss (tan δ) are reported. To assess the evolution of dielectric properties with the interactions between conductive and dielectric fillers, composites were designed with a range of content for PZT (0–30 vol%) and MWCNT (0–1 vol%). The microstructure was composed of PZT-rich and segregated MWCNT-rich regions, which could effectively prevent the formation of macroscopic MWCNT conductive networks and thus reduce the high ohmic loss. Therefore, ε_r increased by a maximum of tenfold, reaching up to 166 by the addition of up to 1 vol% MWCNT to TPU/PZT. More importantly, tan δ remained relatively unchanged at 0.06–0.08, a similar range to that of pure TPU. ε_r/tan δ ratio reached 2870 at TPU/30 vol% PZT/0.5 vol% MWCNT, exceeding most of the reported values. This work demonstrates the potential of three-phase polymer/conductive filler/dielectric filler composites for efficient charge storage applications. Full article

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2020)

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32 pages, 10201 KiB

Open AccessArticle

Comparative Analysis of the Impact of Additively Manufactured Polymer Tools on the Fiber Configuration of Injection Molded Long-Fiber-Reinforced Thermoplastics

by Lukas Knorr, Robert Setter, Dominik Rietzel, Katrin Wudy and Tim Osswald

J. Compos. Sci. 2020, 4(3), 136; https://doi.org/10.3390/jcs4030136 - 15 Sep 2020

Cited by 2 | Viewed by 4165

Abstract

Additive tooling (AT) utilizes the advantages of rapid tooling development while minimizing geometrical limitations of conventional tool manufacturing such as complex design of cooling channels. This investigation presents a comparative experimental analysis of long-fiber-reinforced thermoplastic parts (LFTs), which are produced through additively manufactured [...] Read more.

Additive tooling (AT) utilizes the advantages of rapid tooling development while minimizing geometrical limitations of conventional tool manufacturing such as complex design of cooling channels. This investigation presents a comparative experimental analysis of long-fiber-reinforced thermoplastic parts (LFTs), which are produced through additively manufactured injection molding polymer tools. After giving a review on the state of the art of AT and LFTs, additive manufacturing (AM) plastic tools are compared to conventionally manufactured steel and aluminum tools toward their qualification for spare part and small series production as well as functional validation. The assessment of the polymer tools focuses on three quality criteria concerning the LFT parts: geometrical accuracy, mechanical properties, and fiber configuration. The analysis of the fiber configuration includes fiber length, fiber concentration, and fiber orientation. The results show that polymer tools are fully capable of manufacturing LFTs with a cycle number within hundreds before showing critical signs of deterioration or tool failure. The produced LFTs moldings provide sufficient quality in geometrical accuracy, mechanical properties, and fiber configuration. Further, specific anomalies of the fiber configuration can be detected for all tool types, which include the occurrence of characteristic zones dependent on the nominal fiber content and melt flow distance. Conclusions toward the improvement of additively manufactured polymer tool life cycles are drawn based on the detected deteriorations and failure modes. Full article

(This article belongs to the Special Issue Discontinuous Fiber Composites, Volume II)

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20 pages, 1518 KiB

Open AccessEditor’s ChoiceReview

Carbon Nanotubes (CNTs): A Potential Nanomaterial for Water Purification

by Bharti Arora and Pankaj Attri

J. Compos. Sci. 2020, 4(3), 135; https://doi.org/10.3390/jcs4030135 - 10 Sep 2020

Cited by 97 | Viewed by 20225

Abstract

Nanomaterials such as carbon nanotubes (CNTs) have been used as an excellent material for catalysis, separation, adsorption and disinfection processes. CNTs have grabbed the attention of the scientific community and they have the potential to adsorb most of the organic compounds from water. [...] Read more.

Nanomaterials such as carbon nanotubes (CNTs) have been used as an excellent material for catalysis, separation, adsorption and disinfection processes. CNTs have grabbed the attention of the scientific community and they have the potential to adsorb most of the organic compounds from water. Unlike, reverse osmosis (RO), nanofiltration (NF) and ultrafiltration (UF) membranes aligned CNT membranes can act as high-flow desalination membranes. CNTs provide a relatively safer electrode solution for biosensors. The article is of the utmost importance for the scientists and technologists working in water purification technologies to eliminate the water crisis in the future. This review summarizes about the application of CNTs in water purification. Full article

(This article belongs to the Special Issue Composite Materials for Water Purification)

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16 pages, 8456 KiB

Open AccessArticle

Validation of Fiber Breakage in Simple Shear Flow with Direct Fiber Simulation

by Tzu-Chuan Chang, Abrahán Bechara Senior, Hakan Celik, Dave Brands, Angel Yanev and Tim Osswald

J. Compos. Sci. 2020, 4(3), 134; https://doi.org/10.3390/jcs4030134 - 10 Sep 2020

Cited by 3 | Viewed by 3065

Abstract

This study aims to use particle level simulation to simulate the breakage behavior of glass fibers subjected to simple shear flow. Each fiber is represented as a chain of rods that experience hydrodynamic, interaction, and elastic effects. In order to validate the approach [...] Read more.

This study aims to use particle level simulation to simulate the breakage behavior of glass fibers subjected to simple shear flow. Each fiber is represented as a chain of rods that experience hydrodynamic, interaction, and elastic effects. In order to validate the approach of the model, the simulation results were compared to simple shear flow experiments conducted in a Couette Rheometer. The excluded volume force constants and critical fiber breakage curvature were tuned in the simulation to gain a better understanding of the system. Relaxation of the fiber clusters and a failure probability theory were introduced into the model to solve the fiber entanglement and thus, better fit the experimental behavior. The model showed agreement with the prediction on fiber length reduction in both number average length and weight average length. In addition, the simulation had a similar trend of breakage distribution compared to a loop test using glass fibers. Full article

(This article belongs to the Special Issue Discontinuous Fiber Composites, Volume II)

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15 pages, 6685 KiB

Open AccessArticle

Impact Performance and Bending Behavior of Carbon-Fiber Foam-Core Sandwich Composite Structures in Cold Arctic Temperature

by M.H. Khan, Bing Li and K.T. Tan

J. Compos. Sci. 2020, 4(3), 133; https://doi.org/10.3390/jcs4030133 - 10 Sep 2020

Cited by 10 | Viewed by 3836

Abstract

This study investigates the impact performance, post-impact bending behavior and damage mechanisms of Divinycell H-100 foam core with woven carbon fiber reinforced polymer (CFRP) face sheets sandwich panel in cold temperature Arctic conditions. Low-velocity impact tests were performed at 23, −30 and −70 [...] Read more.

This study investigates the impact performance, post-impact bending behavior and damage mechanisms of Divinycell H-100 foam core with woven carbon fiber reinforced polymer (CFRP) face sheets sandwich panel in cold temperature Arctic conditions. Low-velocity impact tests were performed at 23, −30 and −70 °C. Results indicate that exposure to low temperature reduces impact damage tolerance significantly. X-ray microcomputed tomography is utilized to reveal damage modes such as matrix cracking, delamination and fiber breakage on the CFRP face sheet, as well as core crushing, core shearing and debonding in the Polyvinyl Chloride (PVC) foam core. Post-impact bending tests reveal that residual flexural properties are more sensitive to the in-plane compressive property of the CFRP face sheet than the tensile property. Specifically, the degradation of flexural strength strongly depends on pre-existing impact damage and temperature conditions. Statistical analyses based on this study are employed to show that flexural performance is dominantly governed by face sheet thickness and pre-bending impact energy. Full article

(This article belongs to the Special Issue Carbon Fiber Composites)

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13 pages, 5764 KiB

Open AccessArticle

Effect of Chemical Treatment on Thermal Properties of Jute Fiber Used in Polymer Composites

by Sweety Shahinur, Mahbub Hasan, Qumrul Ahsan and Julfikar Haider

J. Compos. Sci. 2020, 4(3), 132; https://doi.org/10.3390/jcs4030132 - 9 Sep 2020

Cited by 38 | Viewed by 5369

Abstract

In recent years, natural fibers, such as jute has gained significant research interest in order to fabricate fiber reinforced polymer composites. Chemical treatments are generally carried out on the raw fibers for making composites with improved properties. From a composite manufacturing point of [...] Read more.

In recent years, natural fibers, such as jute has gained significant research interest in order to fabricate fiber reinforced polymer composites. Chemical treatments are generally carried out on the raw fibers for making composites with improved properties. From a composite manufacturing point of view, it is important to understand how the treatments can affect the thermal properties of the jute fiber. In the present research, the effects of rot-retardant, fire-retardant and water-retardant treatments on thermal properties of the jute fiber were investigated. Fiber samples were collected from the middle portion of whole jute fiber. Thermo-gravimetric analysis (TGA) and differential scanning calorimetric (DSC) analysis were subsequently conducted on the jute fiber for thermal characterization. The results demonstrated a lower thermal decomposition temperature in the case of fire-retardant treated jute fiber but higher residue at above 400 °C, as compared to the raw and other treated fibers. In general, it was found that chemically treated fibers absorbed less heat, in contrast to the raw jute fiber and heat flow became negative in all cases of the treated fibers. This study provides important information about the thermal properties of the treated jute fibers for manufacturing polymer-based composite materials. Full article

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2020)

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15 pages, 2538 KiB

Open AccessArticle

Piezoresistive and mechanical Behavior of CNT based polyurethane foam

by Enea De Meo, Simone Agnelli, Antonino Veca, Valentia Brunella and Marco Zanetti

J. Compos. Sci. 2020, 4(3), 131; https://doi.org/10.3390/jcs4030131 - 6 Sep 2020

Cited by 7 | Viewed by 4005

Abstract

Carbon nanotubes (CNT) embedded into a polymeric foam demonstrate an enhancement in electrical and mechanical properties of the final nanocomposite. The enhanced material with new characteristics, e.g., piezoresistivity, can be substituted with the traditional metallic material to design sensors, switches, and knobs directly [...] Read more.

Carbon nanotubes (CNT) embedded into a polymeric foam demonstrate an enhancement in electrical and mechanical properties of the final nanocomposite. The enhanced material with new characteristics, e.g., piezoresistivity, can be substituted with the traditional metallic material to design sensors, switches, and knobs directly into a single multifunctional component. Research activities in this field are moving towards a mono-material fully integrated smarts components. In order to achieve this goal, a simple method is developed to produce piezoresistive polyurethane/CNT foams. The novelty consists in applying the dispersion of CNT considering industrial production constrains, in order to facilitate its introduction into a common industrial practice. Three kinds of PU-CNT foam have been prepared and tested: PU-CNT 1.5%, PU-CNT-COOH 1.0%, and PU-CNT-COOH 1.5%. Polyurethane with CNT-COOH showed an insulating-conductive transition phenomenon when the foam reaches the 80% of its compression strain with a Gauge factor (Gf) of about 30. Instead, PU-CNT showed conductivity only at 1.5% of filler concentration and a steady piezoresistive behavior with a Gf of 80. However, this samples did not show the insulating-conductive transition. Having improved the electromechanical properties of final nanocomposite polyurethane foam demonstrates that the proposed method can be applied differently for design sensors and switches. Full article

(This article belongs to the Special Issue Carbon-Based Polymer Nanocomposites)

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39 pages, 8378 KiB

Open AccessEditor’s ChoiceReview

Mechanisms of Origin and Classification of Out-of-Plane Fiber Waviness in Composite Materials—A Review

by Michael Thor, Markus G. R. Sause and Roland M. Hinterhölzl

J. Compos. Sci. 2020, 4(3), 130; https://doi.org/10.3390/jcs4030130 - 4 Sep 2020

Cited by 80 | Viewed by 13018

Abstract

Out-of-plane fiber waviness, also referred to as wrinkling, is considered one of the most significant effects that occur in composite materials. It significantly affects mechanical properties, such as stiffness, strength and fatigue and; therefore, dramatically reduces the load-carrying capacity of the material. Fiber [...] Read more.

Out-of-plane fiber waviness, also referred to as wrinkling, is considered one of the most significant effects that occur in composite materials. It significantly affects mechanical properties, such as stiffness, strength and fatigue and; therefore, dramatically reduces the load-carrying capacity of the material. Fiber waviness is inherent to various manufacturing processes of fiber-reinforced composite parts. They cannot be completely avoided and thus have to be tolerated and considered as an integral part of the structure. Because of this influenceable but in many cases unavoidable nature of fiber waviness, it might be more appropriate to consider fiber waviness as effects or features rather than defects. Hence, it is important to understand the impact of different process parameters on the formation of fiber waviness in order to reduce or, in the best case, completely avoid them as early as possible in the product and process development phases. Mostly depending on the chosen geometry of the part and the specific manufacturing process used, different types of fiber waviness result. In this study, various types of waviness are investigated and a classification scheme is developed for categorization purposes. Numerous mechanisms of wrinkling were analyzed, leading to several recommendations to prevent wrinkle formation, not only during composite processing, but also at an earlier design stage, where generally several influence factors are defined. Full article

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14 pages, 5589 KiB

Open AccessArticle

Investigations on Physico-Mechanical and Spectral Studies of Zn²⁺ Doped P₂O₅-Based Bioglass System

by M. Mohan Babu, P. Syam Prasad, S. Hima Bindu, A. Prasad, P. Venkateswara Rao, Nibu Putenpurayil Govindan, N. Veeraiah and Mutlu Özcan

J. Compos. Sci. 2020, 4(3), 129; https://doi.org/10.3390/jcs4030129 - 4 Sep 2020

Cited by 12 | Viewed by 2920

Abstract

ZnO incorporated phosphate based bioglasses with the composition xZnO–22Na₂O–24CaO–(54-X)P₂O₅ (where X = 2, 4, 6, 8, 10 mol%) were developed by melt-quenching process. The physical, thermal and other structural properties of the glasses were studied in detail. By [...] Read more.

ZnO incorporated phosphate based bioglasses with the composition xZnO–22Na₂O–24CaO–(54-X)P₂O₅ (where X = 2, 4, 6, 8, 10 mol%) were developed by melt-quenching process. The physical, thermal and other structural properties of the glasses were studied in detail. By employing various characterization techniques such as X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) in addition to the energy dispersion spectroscopy (EDS), and Raman spectroscopy, the structural properties were analyzed. Interestingly, physical, thermal and mechanical properties were enhanced with the increasing content of zinc oxide up to 8 mol%, due to the presence of more ionic nature of P–O–Zn bonds than P–O–P bonds in the glass network. The FTIR and Raman analysis revealed the evolution of the phosphate network with increasing zinc concentration and leads to progressive depolymerisation of the glass network. The obtained results from the physical and structural properties of these zinc added calcium phosphate glasses support their potential to use as bone implant applications. Full article

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2020)

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22 pages, 619 KiB

Open AccessEditor’s ChoiceReview

Mechanical Properties of Short Polymer Fiber-Reinforced Geopolymer Composites

by Kinga Korniejenko, Wei-Ting Lin and Hana Šimonová

J. Compos. Sci. 2020, 4(3), 128; https://doi.org/10.3390/jcs4030128 - 1 Sep 2020

Cited by 61 | Viewed by 4270

Abstract

The article describes the state of the art in reinforced geopolymers, taking into consideration various types of polymer fiber reinforcements, such as polypropylene, polyethylene, or polylactic acid. The description is focused on the usage of polymer short fibers and the mechanical properties of [...] Read more.

The article describes the state of the art in reinforced geopolymers, taking into consideration various types of polymer fiber reinforcements, such as polypropylene, polyethylene, or polylactic acid. The description is focused on the usage of polymer short fibers and the mechanical properties of the geopolymer composites. However, to show a wider research background, numerous references are discussed concerning the selected studies on reinforcing geopolymer composites with long fibers and fabrics. The research method applied in the article is the critical analysis of literature sources, including a comparison of new material with other materials used in similar applications. The results of the research are discussed in a comparative context and the properties of the composites are juxtaposed with the properties of the standard materials used in the construction industry. Potential applications in the construction industry are presented. Moreover, the contemporary research challenges for geopolymer materials reinforced with fibers are presented. Full article

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2020)

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14 pages, 5110 KiB

Open AccessArticle

A Nonlinear Analysis Interpretation of Off-Axis Test Results in Metal Matrix Composites

by Jalees Ahmad, Unni Santhosh and Swamy Chandu

J. Compos. Sci. 2020, 4(3), 127; https://doi.org/10.3390/jcs4030127 - 31 Aug 2020

Cited by 1 | Viewed by 2449

Abstract

A unit-cell based micromechanics approach is used to perform nonlinear finite element analyses of off-axis tensile tests on an SCS-6/Ti-6Al-4V composite. The results are used in predicting the global deformation response of the composite that includes the effect of fiber-matrix interface damage. The [...] Read more.

A unit-cell based micromechanics approach is used to perform nonlinear finite element analyses of off-axis tensile tests on an SCS-6/Ti-6Al-4V composite. The results are used in predicting the global deformation response of the composite that includes the effect of fiber-matrix interface damage. The predictions are compared with laboratory test data of uniaxial off-axis specimens. Based on the comparison, it is found that the procedure effectively predicts global composite response with reasonable accuracy under a general multiaxial stress state. Full article

(This article belongs to the Special Issue Metal Composites)

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16 pages, 7674 KiB

Open AccessArticle

Design and Validation of a Modified Compression-After-Impact Testing Device for Thin-Walled Composite Plates

by Markus Linke, Felix Flügge and Aurelio Jose Olivares-Ferrer

J. Compos. Sci. 2020, 4(3), 126; https://doi.org/10.3390/jcs4030126 - 29 Aug 2020

Cited by 10 | Viewed by 3277

Abstract

Thin-walled fibre reinforced composites like carbon fibre reinforced plastics are very susceptible to strength reductions due to low-velocity impact damages. In aerospace engineering, the dominating failure mechanisms of impact damaged composite structures are usually investigated based on the compression after impact (CAI) test [...] Read more.

Thin-walled fibre reinforced composites like carbon fibre reinforced plastics are very susceptible to strength reductions due to low-velocity impact damages. In aerospace engineering, the dominating failure mechanisms of impact damaged composite structures are usually investigated based on the compression after impact (CAI) test procedure. This enables the determination of the influence of impact damages on the static residual compressive strength. CAI testing procedures are typically applicable to composite plates with thicknesses larger than 3–4 mm. If thinner panels are used, they typically fail near one of the loaded edges of the CAI device, in particular the area of the free edge (which is needed for compressing the panel) and not within the free measuring area. As a consequence, the investigated samples cannot be used as valid tests for the evaluation of the residual strength in CAI testing. In order to enable an investigation of the residual strength of thin-walled plates in CAI testing, a CAI testing device is developed based on an available CAI fixture and a standardized one. For comparability reasons, this new device exhibits the same dimensions as standardized fixtures. It shows a significant improvement with respect to standardized devices concerning the measurement of mechanical behaviour during CAI testing. Full article

(This article belongs to the Special Issue Recent Advances in Composite Process Modeling and Characterization)

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15 pages, 4916 KiB

Open AccessArticle

Development of Recyclable and High-Performance In Situ Hybrid TLCP/Glass Fiber Composites

by Tianran Chen, Dana Kazerooni, Lin Ju, David A. Okonski and Donald G. Baird

J. Compos. Sci. 2020, 4(3), 125; https://doi.org/10.3390/jcs4030125 - 24 Aug 2020

Cited by 14 | Viewed by 3232

Abstract

By combining the concepts of in situ thermotropic liquid crystalline polymer (TLCP) composites and conventional fiber composites, a recyclable and high-performance in situ hybrid polypropylene-based composite was successfully developed. The recycled hybrid composite was prepared by injection molding and grinding processes. Rheological and [...] Read more.

By combining the concepts of in situ thermotropic liquid crystalline polymer (TLCP) composites and conventional fiber composites, a recyclable and high-performance in situ hybrid polypropylene-based composite was successfully developed. The recycled hybrid composite was prepared by injection molding and grinding processes. Rheological and thermal analyses were utilized to optimize the processing temperature of the injection molding process to reduce the melt viscosity and minimize the degradation of polypropylene. The ideal temperature for blending the hybrid composite was found to be 305 °C. The influence of mechanical recycling on the different combinations of TLCP and glass fiber composites was analyzed. When the weight fraction ratio of TLCP to glass fiber was 2 to 1, the hybrid composite exhibited better processability, improved tensile performance, lower mechanical anisotropy, and greater recyclability compared to the polypropylene reinforced by either glass fiber or TLCP alone. Full article

(This article belongs to the Special Issue Discontinuous Fiber Composites, Volume II)

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18 pages, 7420 KiB

Open AccessArticle

Characterization of Mechanical Performance of Composites Fabricated Using Innovative Carbon Fiber Wet Laid Process

by Hicham Ghossein, Ahmed Arabi Hassen, Seokpum Kim, Jesse Ault and Uday K. Vaidya

J. Compos. Sci. 2020, 4(3), 124; https://doi.org/10.3390/jcs4030124 - 22 Aug 2020

Cited by 4 | Viewed by 2934

Abstract

Recent innovation in production of optimized nonwoven wet laid (WL) carbon fiber (CF) mats raised the question of optimal translation of the performance and isotropy into composites formed through these dry preforms. This work explores the mechanical behavior of composites produced from WL-CF [...] Read more.

Recent innovation in production of optimized nonwoven wet laid (WL) carbon fiber (CF) mats raised the question of optimal translation of the performance and isotropy into composites formed through these dry preforms. This work explores the mechanical behavior of composites produced from WL-CF mats in conjunction with the microstructure predicted through Object Oriented Finite Element Analysis (OOF). The mats used for the composites were prepared in two dispersion regimes using 25.4 mm long CF. The mixing regimes discussed in the author’s previous work, are identified as Method 1 for the traditional processing regime and Method 2 for the innovative regime that provided optimal nonwoven WL-CF mats. Composite panels from Method 2 mats showed a normalized tensile strength increase of 52% over those from Method 1 panels. Reproducibility analysis of composites made from Method 2 mats demonstrated a standard deviation of 2% in fiber weight content, 2% in tensile modulus and 9% in tensile strength, while composites made from Method 1 mats demonstrated a standard deviation of 5% in fiber weight content, 5% in tensile modulus and 17% in tensile strength. Systematic study of the microstructure and its analysis through OOF confirmed the isotropy translation of mats produced through method 2 to the composites. This study validated the hypothesis that optimal nonwoven mats lead to a well-balanced composite with optimal performance and that non-optimal nonwoven mats do not pack into a well-balanced composite. Full article

(This article belongs to the Special Issue Discontinuous Fiber Composites, Volume II)

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15 pages, 1555 KiB

Open AccessArticle

The Effect of Sodium Alginate-Calcium Chloride Coating on the Quality Parameters and Shelf Life of Strawberry Cut Fruits

by Ghaidaa Alharaty and Hosahalli S. Ramaswamy

J. Compos. Sci. 2020, 4(3), 123; https://doi.org/10.3390/jcs4030123 - 21 Aug 2020

Cited by 47 | Viewed by 8604

Abstract

Strawberry fruits have a short shelf life after harvesting due the physiological factors that enhances ripening such as respiration and transpiration. Sensory properties including color, texture, odor, and flavor are the main factors that makes fresh produce appealing to consumers, and they change [...] Read more.

Strawberry fruits have a short shelf life after harvesting due the physiological factors that enhances ripening such as respiration and transpiration. Sensory properties including color, texture, odor, and flavor are the main factors that makes fresh produce appealing to consumers, and they change very rapidly upon harvest. For this reason, quality preservation is essential during post-harvest handling and storage of strawberry fruits. Quality deterioration rates are higher in strawberry fruit cuts due to the mechanical damage and the loss of their natural protective barriers, resulting in an increase in moisture loss, respiration rates, and the deterioration of their sensory properties. The effect of a sodium alginate-calcium chloride edible coating on quality preservation and shelf life extension of strawberry cut fruits stored at 4 °C was studied. Control samples had mold growth initiated after one week of storage at 4 °C, while the coated fruit samples had a mold free shelf life extension for up to 15 days. The sodium alginate-calcium chloride edible coating was effective in reducing respiration and transpiration rates and delayed the increase of the pH and soluble solid content. Furthermore, the coating delayed surface mold growth for up to 15 days and preserved the sensory properties of the cut fruits such as color and texture. Full article

(This article belongs to the Special Issue Multifunctional Composites)

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18 pages, 7851 KiB

Open AccessArticle

Metamodelling of the Correlations of Preform and Part Performance for Preform Optimisation in Sheet Moulding Compound Processing

by Christian Hopmann, Jonas Neuhaus, Kai Fischer, Daniel Schneider and René Laschak Pinto Gonçalves

J. Compos. Sci. 2020, 4(3), 122; https://doi.org/10.3390/jcs4030122 - 21 Aug 2020

Cited by 5 | Viewed by 2730

Abstract

In the design of parts consisting of long-fibre-reinforced Sheet Moulding Compounds (SMC), the potential for the optimisation of processing parameters and geometrical design is limited due to the high number of interdependent variables. One of the influences on fibre orientations and therefore mechanical [...] Read more.

In the design of parts consisting of long-fibre-reinforced Sheet Moulding Compounds (SMC), the potential for the optimisation of processing parameters and geometrical design is limited due to the high number of interdependent variables. One of the influences on fibre orientations and therefore mechanical part performance is the initial filling state of the compression moulding tool, which is defined by the geometry and positioning of the SMC preform. In the past, response surface methodology and linear regression analysis were successfully used for a simulation-based optimisation of rectangular preform size and position in regard to a part performance parameter. However, the computational demand of these increase exponentially with an increase in the number of design variables, such as in the case of more complex preform geometries. In this paper, these restrictions are addressed with a novel approach for metamodelling the correlation of preform and the resulting mechanical part performance. The approach is applied to predicting the maximum absolute deflection of a plate geometry under bending load. For metamodelling, multiple neural networks (NN) are trained on a dataset obtained by process and structural simulation. Based on the discretisation of the plate geometry used in these simulation procedures, the binary initial filling states (completely filled/empty) of each element are used as inputs of the NNs. Outputs of the NNs are combined by ensemble modelling to form the metamodel. The metamodel allows an accurate prediction of maximum deflection; subsequent validation of the metamodel shows differences in predicted and simulated maximum deflection ranging from 0.26% to 2.67%. Subsequently, the metamodel is evaluated using a mutation algorithm for finding a preform that reduces the maximum deflection. Full article

(This article belongs to the Special Issue Discontinuous Fiber Composites, Volume II)

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12 pages, 3217 KiB

Open AccessArticle

Fast and Facile Synthesis of Pt Nanoparticles Supported on Ketjen Black by Solution Plasma Sputtering as Bifunctional HER/ORR Catalysts

by Chitlada Mani-Lata, Chadapat Hussakan and Gasidit Panomsuwan

J. Compos. Sci. 2020, 4(3), 121; https://doi.org/10.3390/jcs4030121 - 19 Aug 2020

Cited by 12 | Viewed by 4711

Abstract

Hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR) are two core electrochemical processes involved in hydrogen fuel cell (HFC) technology. ORR is a cathodic reaction occurring in HFC, whereas HER can convert the H₂O byproduct from HFCs into H₂ [...] Read more.

Hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR) are two core electrochemical processes involved in hydrogen fuel cell (HFC) technology. ORR is a cathodic reaction occurring in HFC, whereas HER can convert the H₂O byproduct from HFCs into H₂ gas via water splitting. Platinum (Pt)-based catalysts are the most effective catalysts for both reactions. In this work, we used a fast, facile, and chemical-free method, called solution plasma sputtering (SPS), to synthesize Pt nanoparticles supported on Ketjen Black (KB). The discharge time was varied (5, 10, and 20 min) to alter the Pt loading. Characterization results revealed that the plasma did not affect the morphology of KB, and the Pt loading on KB increased with increasing discharge time (5.5–17.9 wt%). Well-crystallized Pt nanoparticles, ~2–5 nm in diameter, were obtained. Electrochemical measurements revealed that Pt/KB exhibited bifunctional catalytic activity toward HER and ORR in 0.5 M H₂SO₄ solution. Both HER and ORR activities enhanced as the loading of Pt nanoparticles increased with a longer discharge time. Moreover, Pt/KB exhibited better HER and ORR stability than a commercial Pt-based catalyst, which was attributed to the stronger adhesion between Pt nanoparticles and KB support. Thus, SPS can be applied as an alternative synthesis method for preparing Pt/KB catalysts for HER and ORR. Full article

(This article belongs to the Special Issue Bimetallic Composites for Oxidation and Reduction Catalysis)

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16 pages, 5912 KiB

Open AccessArticle

Preliminary Mechanical Analysis of Rubber-Cement Composites Suitable for Additive Process Construction

by Matteo Sambucci, Danilo Marini, Abbas Sibai and Marco Valente

J. Compos. Sci. 2020, 4(3), 120; https://doi.org/10.3390/jcs4030120 - 18 Aug 2020

Cited by 29 | Viewed by 3882

Abstract

Additive manufacturing for cementitious materials represents the most attractive frontier in the modern context of Construction 4.0. In addition to the technological progress of printing systems, the development of functional and low environmental impact printable mixtures is one of the current challenges of [...] Read more.

Additive manufacturing for cementitious materials represents the most attractive frontier in the modern context of Construction 4.0. In addition to the technological progress of printing systems, the development of functional and low environmental impact printable mixtures is one of the current challenges of digital fabrication in building and architectural fields. This paper proposes a preliminary physical-mechanical analysis on environmentally friendly mortars, compatible with the extrusion-based printing process, made up of recycling rubber aggregates deriving from end-of-life tires. In this study, two groups of rubber particle samples (0–1 mm rubber powder and 2–4 mm rubber granules) were used to partially/totally replace the mineral fraction of the reference printable mixture. Four tire rubber powder-granules proportions were investigated and control mortar (100% sand) was also prepared to compare its properties with those of the rubber-cement samples in terms of printability properties, mechanical strength, ductility, and structural isotropy. Based on the experimental results, the rubber aggregates increase the mixture fluidity, promoting better inter-layer adhesion than the neat mix. This leads to greater mechanical isotropy. As already investigated in other research works on Rubber-Concrete technology, the addition of rubber particles increases the ductility of the material but reduces its mechanical strength. However, by correctly balancing the fine and coarse rubber fraction, promising physical-mechanical performances were demonstrated. Full article

(This article belongs to the Special Issue Progress in Rubber Blends and Composites Technology)

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16 pages, 3935 KiB

Open AccessArticle

Influence of Fiber Coating and Polymer Modification on Mechanical and Thermal Properties of Bast/Basalt Reinforced Polypropylene Hybrid Composites

by Anjum Saleem, Luisa Medina and Mikael Skrifvars

J. Compos. Sci. 2020, 4(3), 119; https://doi.org/10.3390/jcs4030119 - 18 Aug 2020

Cited by 11 | Viewed by 3272

Abstract

Natural fibers, such as kenaf, hemp, and flax, also known as bast fibers, offer several benefits such as low density, carbon dioxide neutrality, and less dependence on petroleum sources. Their function as reinforcement in polymer composites offers a great potential to replace a [...] Read more.

Natural fibers, such as kenaf, hemp, and flax, also known as bast fibers, offer several benefits such as low density, carbon dioxide neutrality, and less dependence on petroleum sources. Their function as reinforcement in polymer composites offers a great potential to replace a segment of the glass fiber-reinforced polymer composites, especially in automotive components. Despite their promising benefits, they cannot meet the structural and durability demands of automobile parts because of their poor mechanical properties compared to glass fibers. The focus of this research work was the improvement of the mechanical property profile of the bast fiber reinforced polypropylene composites by hybridization with natural high-performance basalt fibers and the influence of basalt fibers coating and polymer modification at the mechanical and thermal properties of the composites. The specific tensile strength of the composite with polymer tailored coating was 39% and the flexural strength was 44% higher than the composite with epoxy-based basalt fibers. The mechanical performance was even better when the bast/basalt hybridization was done in maleic anhydride modified polymer. This led to the conclusion that basalt fibers sizing and polymer modification are the deciding factors in defining the optimal mechanical performance of the composites by influencing the fiber-matrix interaction. The composites were analyzed for their mechanical, thermal, and morphological properties. The comparison of bast/basalt hybrid composite with bast/glass fibers hybrid composite showed a 32% higher specific flexural and tensile strength of the basalt hybrid composite, supporting the concept of basalt fibers as a natural alternative of the glass fibers. Full article

(This article belongs to the Special Issue Advanced Fiber Reinforced Polymer Composites)

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17 pages, 2664 KiB

Open AccessArticle

Nanocomposite of Graphene Oxide Encapsulated in Polymethylmethacrylate (PMMA): Pre-Modification, Synthesis, and Latex Stability

by Hui Wang, Letian Wang, Shanyu Meng, Hanxue Lin, Melanie Correll and Zhaohui Tong

J. Compos. Sci. 2020, 4(3), 118; https://doi.org/10.3390/jcs4030118 - 17 Aug 2020

Cited by 13 | Viewed by 3515

Abstract

The compatibility of graphene oxide with its dispersion medium (polymer) plays a critical role in the formation of nanocomposite materials with significant property improvements. Environmentally friendly miniemulsion polymerization, which allows a formation of nanoencapsulation in an aqueous phase and high molecular weight polymer/composite [...] Read more.

The compatibility of graphene oxide with its dispersion medium (polymer) plays a critical role in the formation of nanocomposite materials with significant property improvements. Environmentally friendly miniemulsion polymerization, which allows a formation of nanoencapsulation in an aqueous phase and high molecular weight polymer/composite production is one promising method. In this study, we screened a series of amphiphilic modifiers and found that the quaternary ammonium (ar-vinyl benzyl) trimethyl ammonium chloride (VBTAC) pending carbon double bonds could effectively modify the graphene oxide (GO) to be compatible with the organophilic monomer. After that, free radical miniemulsion polymerization successfully synthesized stable latex of exfoliated poly (methyl methacrylate) (PMMA)/ GO nanocomposite. The final latex had an extended storage life and a relatively uniform particle size distribution. X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) analysis of this latex and its films indicated successful encapsulation of exfoliated nano-dimensional graphene oxide inside a polymer matrix. Full article

(This article belongs to the Special Issue Graphene Oxide Composites)

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23 pages, 3971 KiB

Open AccessReview

Multifaceted Hybrid Carbon Fibers: Applications in Renewables, Sensing and Tissue Engineering

by Chandreyee Manas Das, Lixing Kang, Guang Yang, Dan Tian and Ken-Tye Yong

J. Compos. Sci. 2020, 4(3), 117; https://doi.org/10.3390/jcs4030117 - 16 Aug 2020

Cited by 5 | Viewed by 3430

Abstract

The field of material science is continually evolving with first-class discoveries of new nanomaterials. The element carbon is ubiquitous in nature. Due to its valency, it can exist in various forms, also known as allotropes, like diamond, graphite, one-dimensional (1D) carbon nanotube (CNT), [...] Read more.

The field of material science is continually evolving with first-class discoveries of new nanomaterials. The element carbon is ubiquitous in nature. Due to its valency, it can exist in various forms, also known as allotropes, like diamond, graphite, one-dimensional (1D) carbon nanotube (CNT), carbon fiber (CF) and two-dimensional (2D) graphene. Carbon nano fiber (CNF) is another such material that falls within the category of CF. With much smaller diameters (around hundreds of nanometers) and lengths in microns, CNFs have higher aspect (length to diameter) ratios than CNTs. Because of their unique properties like high electrical and thermal conductivity, CNFs can be applied to many matrices like elastomers, thermoplastics, ceramics and metals. Owing to their outstanding mechanical properties, they can be used as reinforcements that can enhance the tensile and compressive strain limits of the base material. Thus, in this short review, we take a look into the dexterous characteristics of CF and CNF, where they have been hybridized with different materials, and delve deeply into some of the recent applications and advancements of these hybrid fiber systems in the fields of sensing, tissue engineering and modification of renewable devices since favorable mechanical and electrical properties of the CFs and CNFs like high tensile strength and electrical conductivity lead to enhanced device performance. Full article

(This article belongs to the Special Issue Carbon Fiber Composites)

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44 pages, 9992 KiB

Open AccessReview

Recent Progress in the Study of Thermal Properties and Tribological Behaviors of Hexagonal Boron Nitride-Reinforced Composites

by Maryam Khalaj, Sanaz Zarabi Golkhatmi, Sayed Ali Ahmad Alem, Kahila Baghchesaraee, Mahdi Hasanzadeh Azar and Shayan Angizi

J. Compos. Sci. 2020, 4(3), 116; https://doi.org/10.3390/jcs4030116 - 14 Aug 2020

Cited by 35 | Viewed by 6369

Abstract

Ever-increasing significance of composite materials with high thermal conductivity, low thermal expansion coefficient and high optical bandgap over the last decade, have proved their indispensable roles in a wide range of applications. Hexagonal boron nitride (h-BN), a layered material having a high thermal [...] Read more.

Ever-increasing significance of composite materials with high thermal conductivity, low thermal expansion coefficient and high optical bandgap over the last decade, have proved their indispensable roles in a wide range of applications. Hexagonal boron nitride (h-BN), a layered material having a high thermal conductivity along the planes and the band gap of 5.9 eV, has always been a promising candidate to provide superior heat transfer with minimal phonon scattering through the system. Hence, extensive researches have been devoted to improving the thermal conductivity of different matrices by using h-BN fillers. Apart from that, lubrication property of h-BN has also been extensively researched, demonstrating the effectivity of this layered structure in reduction of friction coefficient, increasing wear resistance and cost-effectivity of the process. Herein, an in-depth discussion of thermal and tribological properties of the reinforced composite by h-BN will be provided, focusing on the recent progress and future trends. Full article

(This article belongs to the Special Issue Thermal Behavior of Thermoset Composites)

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11 pages, 7218 KiB

Open AccessArticle

Proof of Concept for Pultrusion Control by Cure Monitoring Using Resonant Ultrasound Spectroscopy

by Christian Pommer and Michael Sinapius

J. Compos. Sci. 2020, 4(3), 115; https://doi.org/10.3390/jcs4030115 - 14 Aug 2020

Cited by 6 | Viewed by 2506

Abstract

The increasing demand for low cost consistent quality composite materials, especially of the automotive industry, creates the necessity for fast high quality processes. Pultrusion is one of the processes that can fulfill this demand. While the process is highly automated, manufacturing parameters still [...] Read more.

The increasing demand for low cost consistent quality composite materials, especially of the automotive industry, creates the necessity for fast high quality processes. Pultrusion is one of the processes that can fulfill this demand. While the process is highly automated, manufacturing parameters still have to be chosen manually. The choice of line speed, mould temperature and injection pressure is based on best practice and therefore requires manual optimization that results in cost intensive manufacturing errors and suboptimal machine productivity. This paper presents a possible solution for this problem by providing an on-line cure monitoring approach that allows to overcome this challenge. Resonant Ultrasonic Spectroscopy (RUS) shows a high potential for in-line cure monitoring inside the pultrusion tool. RUS has been adapted for the first time in a pultrusion process. This paper focuses on the successful application of this technique to control the pultrusion process based on the state of cure of the material inside of the tool. As one of the only techniques for in-line cure monitoring which can be used continuously in closed tools despite high abrasion, it provides a new insight into the pultrusion process. Full article

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11 pages, 4212 KiB

Open AccessArticle

Process Chain Optimization for SWCNT/Epoxy Nanocomposite Parts with Improved Electrical Properties

by Manuel V. C. Morais, Marco Marcellan, Nadine Sohn, Christof Hübner and Frank Henning

J. Compos. Sci. 2020, 4(3), 114; https://doi.org/10.3390/jcs4030114 - 14 Aug 2020

Cited by 2 | Viewed by 2251

Abstract

Electrically conductive nanocomposites present opportunities to replace metals in several applications. Usually, the electrical properties emerging from conductive particles and the resulting bulk values depend on the micro/nano scale morphology of the particle network formed during processing. The final electrical properties are therefore [...] Read more.

Electrically conductive nanocomposites present opportunities to replace metals in several applications. Usually, the electrical properties emerging from conductive particles and the resulting bulk values depend on the micro/nano scale morphology of the particle network formed during processing. The final electrical properties are therefore highly process dependent. In this study, the electrical resistivity of composites made from single-walled carbon nanotubes in epoxy was investigated. Three approaches along the processing chain were investigated to reduce the electrical resistivity of nanocomposites-the dispersion strategy in a three-roll mill, the curing temperature, and the application of electric fields during curing. It was found that a progressive increase in the shear forces during dispersion leads to a more than 50% reduction in the electrical resistivities. Higher curing temperatures of the nanocomposite resin also lead to a decrease of around 50% in resistivity. Furthermore, a scalable resin transfer molding set-up with gold-coated electrodes was developed and tested with different mold release agents. It has been shown that curing the material under electric fields leads to an electrical resistivity approximately an order of magnitude lower, and that the properties of the mold release agent also influence the final resistivity of different samples in the same batch. Full article

(This article belongs to the Special Issue Discontinuous Fiber Composites, Volume II)

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J. Compos. Sci., Volume 4, Issue 3 (September 2020) – 61 articles

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