Spacer Fabrics Research Articles

Mechanical performance of cementitious composites reinforced with weft-knitted spacer fabrics under static flexural and impact loading

Though weft-knitted spacer fabric made from high-performance continuous fiber offers great potential for lightweight composite with high energy absorption characteristic, it has yet to be substantially studied in the field of cement-based structural materials. In this paper, a series of newly developed aramid weft-knitted spacer fabrics were applied to reinforce the eco-friendly cementitious matrix. The mechanical properties and failure behaviors of composites were investigated via the three-point bending test and impact test systematically. XCT was then performed to reveal the underlying damage mode of composites. The experimental results indicated that aramid weft-knitted spacer fabrics were highly beneficial reinforcements for cementitious composites due to their great bonding and mechanical anchoring with matrix. The larger ductile deformation and higher damage tolerance of composites were obtained by the increase of spacer yarn density and surface yarn density. The asymmetrical structure corresponding to the different density of surface layer could further enhance bearing capacity by altering the stress transfer.

Numerical simulation and image analysis of thermal behavior of spacer fabric

Numerical simulation and image analysis of thermal behavior of spacer fabric

Large-scale manufacturing of soluble hemostatic spacer dressing with excellent mechanical and comfortable properties

Death from acute hemorrhage is a major life-threatening. Spacer fabrics-based composite dressings have been widely concerned because of their good hemostasis and protection in wound healing, but the poor liquid absorption and compression recovery properties hinder their utilization. Herein, we report a soluble hemostatic spacer dressing based on a braided yarn of PTFE (core yarn)/carboxymethylated viscose (shell yarn) as the skin contact layer, a wrapped yarn of nylon monofilament (core yarn)/Coolmax (shell yarn) as the spacer layer, and UHMWPE yarn as the waterproof layer for wound healing. Among these, carboxymethylated viscose can stop bleeding, while PTFE has low adhesion and ensures the structural integrity of the spacer fabric. Moreover, the nylon monofilament can endow the dressing with excellent comfortability, resilience, and fatigue resistance. Coolmax can absorb blood. The as-prepared spacer dressing shows excellent mechanical, comfortable, and hemostasis properties. F2 had a hemostasis time of 5.15 min, a low coagulation index of 7.96%, a hemolysis rate of 0.98%, and a blood absorption rate of 159.09%. This work presents an integrated molding method to achieve large-scale manufacturing of spacer dressing, which is expected to guide materials design for future innovations in biomedical applications.

Compressive properties investigation of “stress transformer” based on high-distance woven spacer fabric design

High-distance woven spacer fabrics have been developed into a variety of special textile products for a wide range of applications. As a type of sandwich structure, their applications are heavily dependent on their compressive properties. In this study, the compressive properties of high-distance woven spacer flexible inflatable composites (HDWSFICs) have been evaluated by varying the indenter diameter, initial inflation pressure, and spacer yarn density. The experimental results showed that the compression process can be divided into three stages, including the Contact Stage, the Stress Transition Stage and the Densification Stage. In the Stress Transition Stage, the HDWSFICs can transform compressive load into tension stress, and especially local stress into integral stress, which can be considered a “Stress Transformer”. The existence of the spacer yarns allows the inflatable composites to bear more than three times the compressive load of the inflatable membrane material itself. The compressive modulus increases with spacer yarn density and initial inflation pressure, thus the stiffness of HDWSFICs can be designed. The findings of this study may provide ideas for the design of a “Stress Transformer” and theoretical references for the development of high-distance woven spacer inflatable composites with excellent mechanical properties.

Aloe vera gel finished 3D spacer knitted sports textiles

In this study, polyester fibre is converted to 3D spacer knitted fabric of fully hydrophobic in nature. In this study, polyester fibre has been converted in to 3D spacer knitted fabric which is fully hydrophobic in nature. The silicone based hydrophilic softeners are applied on the surface of one side of 3D spacer fabric to make it hydrophilic layer using spraying techniques. The hydrophilic layer of 3D spacer fabric is then finished with aloe vera gel for its use in sportswear. Bioactive compounds available in aloe vera gel, such as tannin, phenols, saponins, terpenoids, and flavonoids, have been tested using a thin layer chromatographic technique. Aloe vera gel extract and gel finished fabrics are assessed for antibacterial activity by using agar well diffusion method and parallel streak method. The test results provide excellent antibacterial property at the inhibition zone of 33mm against Escherichia coli and 35mm against Staphylococcus aureus. Physical and comfort properties of aloe vera gel finished spacer fabric and normal polyester knitted sports fabric are assessed using ASTM and AATCC standards. The test results obtained from aloe vera gel finished spacer fabric are found higher with respect to fabric thickness, fabric weight, water vapour permeability, bursting strength, vertical wickability, and air permeability as compared to normal polyester knitted sports fabric. It can also be used for protective textiles, agro textiles, aerospace textiles and medical textiles.

Study on thermal, mechanical, and wettability properties of three-dimensional weft-knitted spacer fabrics with various silica aerogels coating

This study investigated the thermal, mechanical, and oil absorption-retention properties at various temperatures (20°C, 30°C, 40°C, 50°C, and 60°C) of three-dimensional (3D) weft-knitted spacer fabrics with optimal performance of silica aerogel coating that demands exceptional attention. Silica aerogels and (silica aerogels + poly(vinyl-alcohol)) sols were prepared and coated on 3D weft-knitted spacer fabrics to study and compare the basic properties, i.e. thermal resistance, thermal conductivity, tensile strength, initial modulus, compression, bending rigidity, wettability, oil absorption, and retention capacity. The scanning electron microscopy and Fourier transform infrared spectroscopy studies were completed to understand the influence of both coatings on 3D weft-knitted spacer fabrics such as surface morphology and molecular interaction. The tensile, bending, and compression tests of 3D weft-knitted spacer fabrics were accomplished to check their durability, bendability, and compressibility. All the coated samples (both silica aerogels and (silica aerogels + poly(vinyl-alcohol))) showed greater thermal resistance (0.0971 ± 0.0003 m2 KW−1 and 0.0912 ± 0.0005 m2 KW−1) and lower thermal conductivity (0.0309 ± 0.0001 Wm−1 K−1 and 0.0329 ± 0.0002 Wm−1 K−1) with better thermal stability than the uncoated samples, most specifically coated sample 5. Besides, coated sample 5 exposed higher oil absorption ((7.91 ± 0.06 g/g and 7.88 ± 0.06 g/g) and (7.56 ± 0.04 g/g and 7.53 ± 0.04 g/g)) and retention ((90.10 ± 0.53% and 89.07 ± 0.55%) and (92.47 ± 0.49% and 91.43 ± 0.47%)) capacity for vegetable and engine oil in all conditions, especially at 40°C. The outcomes demonstrated that both coatings played a vital role in the thermal, mechanical, and wettability properties of 3D weft-knitted spacer fabrics with statistically significant performance ( p < 0.05). Moreover, these new types of sorbents (3D weft-knitted spacer fabrics) have better consequences in most cases than conventional knitted, woven, and nonwoven sorbents. Hence, these 3D weft-knitted spacer fabrics could be used for industrial applications as eco-friendly and multifunctional oil sorbent materials.

Vibration Isolation Properties of Novel Spacer Fabric with Silicone Inlay.

Spacer fabrics are good for impact force absorption and have the potential for vibration isolation. Inlay knitting of additional material to the spacer fabrics can give reinforcement to the structure. This study aims to investigate the vibration isolation properties of three-layer sandwich fabrics with silicone inlay. The effect of the presence of the inlay, inlay patterns and materials on the fabric geometry, vibration transmissibility and compression behaviour were evaluated. The results showed that the silicone inlay increases the unevenness of the fabric surface. The fabric using polyamide monofilament as the spacer yarn in the middle layer creates more internal resonance than that using polyester monofilament. Silicone hollow tubes inlay increases the magnitude of damping vibration isolation, whereas inlaid silicone foam tubes have the opposite effect. Spacer fabric with silicone hollow tubes inlaid by tuck stitches has not only high compression stiffness but also becomes dynamic, showing several resonance frequencies within the tested frequency range. The findings show the possibility of the silicone inlaid spacer fabric and provide a reference for developing vibration isolation materials with knitted structure and textiles materials.

Mechanical properties of shear thickening fluid filled warp-knitted spacer fabrics

This paper reports the compressive behavior and low-velocity impact behavior of warp-knitted spacer fabrics (WKSFs) filled with shear thickening fluid (STF) when subjected to quasi-static compression and low-velocity impact loadings, respectively. In the steady rheological test, the STF experiences a shear thickening transition at a critical shear rate. Besides, the critical shear rate decreases with the increase of silica mass fraction. The compression curves of WKSFs filled with STF composites were consistent with those of WKSFs, including initial, elastic and compaction stage. As the compression speed increases, the overall compression load values of WKSF and WKSFs filled with STF composite increase. Moreover, the compression load of composite increases with the increase of silica mass fraction. Compared with WKSFs, WKSFs filled with STF composite composites need more work to deform under the same strain. The impact result reveals that STF-filled WKSF would absorb more energy and keep the peak load at a lower level than WKSF under the same impact loadings. In a certain range, the energy absorption of composites becomes more excellent with the increasing silica mass fraction. However, over a certain range, the energy absorption of the composite decreases with the increase of the mass fraction of silica. It was concluded that the STF-filled WKSF composite could be expected as a damping or energy-absorptive material for human body protection.

Ngā Pūrakau No Ngā Rākau: Stories from Trees

Within te ao Māori—the Māori world view—whakapapa, or genealogical connections, link together every being. Relationships with trees are traced through ancestral bonds that are recited through storytelling. Trees are tūpuna, elders, who hold knowledge, reflected in the etymology of rākāu (tree) being the pū (base) of pūrākau (stories). The Atua Tāne Mahuta, sought ngā kete o te wānanga, the three baskets of knowledge. The wānanga is a place of learning and was brought into being by the god of trees, forests, and birds. Ngāpuhi artist Nova Paul’s experimental films are made with kaupapa Māori values. Her most recent films Rākau and Hawaiki, both 2022, reflect on lessons from trees, the latter premiering at the Sundance Film Festival 2023. These films are not so much about trees as by trees. Nova has made film developer from foliage of the trees that are filmed so that, for example, the riverside pōhutukawa tree is processed in a bath of pōhutukawa chlorophyl developer. For Nova, this process reveals not only an image but the mauri (life force) of the tree through the taking and then the making of her tree films. The films produced are more like an arboreal self-portrait: trees speaking directly through an embodied medium. If trees process sunlight to produce chlorophyl, here, chlorophyl produces images of light in order to communicate messages across species. The tohunga Reverend Māori Marsden wrote that photographic technologies might provide spiritual insight into perceiving life force: “Those with the powers and insight and perceptions (Matakite), perceived mauri as an aura of light and energy radiating from all animate life. It is now possible to photograph the mauri in living things.” In previous films, Nova experimented with colour-separation techniques to pull apart the fabric of time and space, which Tessa wrote about for the Third Text online forum “Decolonising Colour?” That article was translated into Spanish for the book Pensamientos Migrantes: Intersecciones cinematográficas by the Colombian experimental film publishers Hambre Cine (2020). Continuing with a conversation about the ways in which experimental film practices can open up a space for decolonial thought and Indigenous epistemologies, Nova and Tessa co-write this paper in order to share the pūrākau (stories) arising from the images of these rākāu (trees), in which photosynthesis, filmmaking, and spirit, are intertwined, and where the mauri (life force) is revealed.

Thermodynamic qualification of knitted spacer fabrics for use as insulation box insert in the context of refrigerated transport containers in the logistics sector

Temperature-sensitive products such as refrigerated and frozen goods pose particular challenges for logistics. Against the background of the mobility shift towards electric vehicles and the current challenges of temperature-stable transport in the field of pharmaceutical, esp. vaccine logistics in the context of the SARS-CoV-2 pandemic, new, energy-efficient vehicle equipment is needed to maintain cold chains. Known refrigeration concepts are designed to cool the entire cargo hold. In addition, the goods cannot be removed from the vehicle while maintaining the cold chain. An insulating effect of containers is typically achieved by using foamed polystyrene (Styrofoam). On the one hand, these structures have a very good insulating effect, but on the other hand, they cannot be reduced in volume during recirculation and are problematic with regard to recycling. The aim of the research presented here is therefore to develop a knitted box that is designed as a volume-reducible, rigid but foldable box. This can be used as a supplement to existing transport container systems and therefore can be inserted in the transport container. The knitted box performs as insulation when the transported goods are actively cooled inside the box, which is more sustainable and flexible than recent insulation solutions. Knitted fabrics, especially spacer fabrics, have advantageous thermo-physical properties for this application due to their structural design. In the course of a research project, various spacer fabrics were tested for their thermo-physical suitability as insulation materials. It was found that knitted predetermined folding lines represent an insulation gap. Based on this, a new structure was developed which, due to its structural design, compensates for cold or thermal bridges at vertices and edges of the box. The results show that the knitted corrugated structure insulates better than the knitted spacer fabrics with predetermined folding lines. A thermal imaging camera was used to identify critical points for heat transfer.

Review on the design and application of concrete canvas reinforced with spacer fabric

Concrete canvas reinforced with spacer fabric has increasingly gained popularity due to its lightweight, great flexibility, high strength and low contamination compared to ordinary concrete. In order to fully explore the structure and performance of this novel composite, this review illustrates how to design high-performance concrete canvas and presents a summary of recent application status of it. Firstly, the structure and properties of knitted and woven spacer fabric and concrete material that comprise concrete canvas is introduced. Secondly, internal and external mechanisms affecting the properties of concrete canvas have been described. To illustrate how to evaluate and test the mechanical behavior of concrete canvas, typical mechanical experiments such as tensile and flexural experiment and failure mechanisms are explained. In terms of the characteristics of concrete canvas, the present article reviews current applications of it in disaster relief tent, slope protection, ditch lining and furniture design areas. Nevertheless, its practical applications are still in the preliminary stage, it is of great necessity to expand its application from the point of view of replacing traditional materials, changing structural design, external reinforcement and perfecting performance evaluation system.

Numerical simulation for heat transfer of silica-aerogel filled 3-D stitched spacer fabric composites

Spacer fabrics and their composites have great advantages of being excellent heat insulation materials because of their cavity structure characteristics. However, there are few researches on the thermal insulation of spacer fabric composites with different spacer shapes and geometric parameters. In this work, stitched spacer fabric composites filled with silica aerogel with rectangular, triangular and trapezoidal spacer shapes and their models were designed. The results of experiments and simulations show that the temperature distribution of spacer fabric composites has good consistency at high temperature. By analyzing the heat transfer results of composites with different geometric parameters, it was found that the length of the connecting layer between the top and bottom layers and the distance between two adjacent sutures in the top layer affect the minimum and maximum temperatures of the top surface.

A Philosophical Approach toward Electromagnetic Wave Absorption

This paper explains the absorption of an electromagnetic wave within a physical body. We provide a description of how an elementary physical particle absorbs electromagnetic waves within its structure and, after absorption, how this particle keeps it in memory and emits it. This absorption is like the eating of cosmological food by physical entities. This paper proposes that the universe is comprised of cosmological, physical, biological, psychological, and intellectual worlds that all follow parallel laws within their referred science. The paper creates a model of the elementary physical particle (EPP) using the parallel logic of the biological DNA model. This model is capable of explaining the emission, absorption, and memorization of physical signals. Several cosmological mysteries, like the interconvertibility of electric and magnetic fields, attraction, repulsion, space fabric, etc., unfold while disclosing the absorption and emission processes. The philosophical correctness of this paper is validated through the unification of multidisciplinary aspects, and its scientific correctness is validated by its logical consistency with the results of well-known experiments. The theory clarifies the “cause” within nature, and by analyzing the “effects”, we can reach new realities of the cosmological world.

Precarious Emplacement in Croatia: Conceptualising More-Than-Transient Migration on the Balkan Route

The article argues that the dynamic of migration on the Balkan route is changing into something more than transit. Croatia is presented as a case in point of a site where former migration aspirations are redefined as migrants encounter various types of bordering mechanisms that decelerate migration and begin developing relations with other residents. We argue that the dynamic of mobility and immobility and the ways it entangles localities en route are crucial for understanding the changing migration patterns in the Balkans. We overview concepts such as “stuckness”, “waiting”, “permanent temporariness”, “limbo”, and “liminality”, which describe the ways in which migrants navigate between temporary and permanent states of movement and residence. Additionally, the article develops the concept of “precari¬ous emplacement” in order to move beyond transit and to capture the ambiguities between moving and staying, temporariness and permanence, and inclusion and exclusion. The concept highlights that the practices related to settling, along with the social interactions with other residents associated with them, occur in conditions of uncertainty and social marginalisation. Precarious emplacement encompasses the ways precarity permeates migrants’ experiences and the fabric of post-war and post-socialist urban spaces and relations they move through and come to inhabit. The article concludes by arguing that, given the heterogeneity of migrants’ life trajectories, the concept of a “transit migrant” may obscure the vulnerabilities migrants experience during periods of immobility, and it advocates for a more nuanced conceptual approach.

A 20-year clinical survey of radiotherapy prostheses at the Clinic for Maxillofacial Prosthetics of Tokyo Medical and Dental University Hospital.

To identify secular trends in the use of radiotherapy prostheses in the Clinic for Maxillofacial Prosthetics at Tokyo Medical and Dental University Hospital and to ascertain patient characteristics and future needs. The study included all patients who visited the clinic between January 1, 2000, and December 31, 2019. Data on numbers of cases, gender and age, numbers and types of radiotherapy prostheses, primary cancer site, and time required for prosthesis fabrication during the study period were collected from medical records and retrospectively analyzed. During the 20-year study period, 1,066 prostheses were fabricated for 1,135 cases. In most years, at least 60% of cases were male. The mean age increased from 60.6 to 67.1 years during the study period, and the number of cases older than 70 years increased over time. The most common cancer site was the tongue, and the most common type of radiotherapy prosthesis was a spacer. The mean time for spacer fabrication was 11 days. During a recent 20-year period, mean age and the proportion of elderly patients requiring savers increased. When treating elderly patients, prosthodontists responsible for fabricating radiotherapy prostheses must collaborate effectively with radiation oncologists.

Asymmetric Thermal and Water Vapor Transport of Polyester Spacer and Cotton Nonwoven Fabric Assembly

ABSTRACT Spacer fabric is often used in cushions, footwear, filter material, and other products because of its high air permeability and three-dimensional (3D) structure. However, for practical applications, it is typically combined with other materials. We investigated the thermal properties and water vapor permeability of assembly-combined thicker spacer (16 mm) and various cotton nonwoven fabrics. The assembly-combined lightest nonwoven (30 g/m2) and spacer fabric exhibited the highest thermal resistance, increasing by 66.62% compared with the bare spacer fabric; however, no significant difference was observed when combined with the heaviest woven fabric (60 g/m2). Furthermore, the fabric arrangement during assembly could affect the heat and moisture-transfer efficiencies. The assembly-combined lightest nonwoven (30 g/m2) and spacer fabric under the upward test condition exhibited the highest thermal resistance, highest Clo, lowest heat transfer coefficient, highest insulation ratio, and lowest evaporation resistance among all assemblies. Higher thermal resistance and lower evaporative resistance could benefit physiological comfort. However, the assembly-combined heaviest nonwoven and spacer fabric under the downward test condition exhibited similar thermal resistance to the spacer fabric and the highest evaporation resistance. The asymmetric heat- and moisture-transfer properties of a porous assembly can contribute toward developing new materials for applications in other engineering fields.

SiO2 aerogels (SAs) coating on the surface of 3D weft-knitted spacer fabrics (WKSFs) used as sorbent in oil spill cleanup

Oily wastewater and advanced manufacturing organic pollutants are posing a serious global threat to the environment. Herein, SiO2 aerogels prepared from tetraethylorthosilicate (C8H20O4Si) by sol-gel method were coated on various 3D weft-knitted spacer fabrics (WKSFs) to study and compare the oil spill cleanup behavior in different temperatures (20 °C, 30 °C, 40 °C, 50 °C, and 60 °C), oil, and water medium. SEM and BET were used to observe the surface morphology and specific surface area of WKSFs. FTIR-ATR and XRD for the microstructure of fabrics were used to characterize the surface changes induced by the silica aerogel coating. TGA was performed to clarify the thermal degradation of WKSFs. The findings demonstrated that entirely the sorbents, particularly sorbent 2, ensured significant oil weight gain (%) and retention rate (%) in all cases. Sorbent 2 (with a weight of 350 g/m2, a thickness of 3 mm, a stitch density of 1.58/inch, a fabric density of 117 kg/m3, and a spacer yarn arrangement angle of 79.96°) showed a higher oil weight gain (%) and retention rate (%) of ((763 ± 2.31 %, 758 ± 2.08 %, and 740 ± 2.52 %) and (88.92 ± 0.87 %, 88.74 ± 0.68 %, and 85.88 ± 1.02 %)) for vegetable oil and ((698 ± 2.65 %, 693 ± 2.52 %, and 673 ± 2.65 %) and (91.18 ± 0.83 %, 90.82 ± 0.75 %, and 88.16 ± 0.90 %)) for engine oil in temperature, oil, and water medium, respectively. The statistical study revealed that coated WKSFs performed significantly at the 0.05 level (P = 0.000). The outcomes also revealed that the varieties of 3D fabric physical structures, specific surface areas, pore sizes, pore volumes, porosity ratios, water contact angles, silica aerogel add-on %, surface roughness, thermal behaviors, temperatures, and oil characteristics all played a significant effect on oil weight gain and retention capacity, especially in the oil spill cleanup performance.

Copper Iodide on Spacer Fabrics as Textile Thermoelectric Device for Energy Generation.

The integration of electronic functionalities into textiles for use as wearable sensors, energy harvesters, or coolers has become increasingly important in recent years. A special focus is on efficient thermoelectric materials. Copper iodide as a p-type thermoelectrically active, nontoxic material is attractive for energy harvesting and energy generation because of its transparency and possible high-power factor. The deposition of CuI on polyester spacer fabrics by wet chemical processes represents a great potential for use in textile industry for example as flexible thermoelectric energy generators in the leisure or industrial sector as well as in medical technologies. The deposited material on polyester yarn is investigated by electron microscopy, x-ray diffraction and by thermoelectric measurements. The Seebeck coefficient was observed between 112 and 153 µV/K in a temperature range between 30 °C and 90 °C. It is demonstrated that the maximum output power reached 99 nW at temperature difference of 65.5 K with respect to room temperature for a single textile element. However, several elements can be connected in series and the output power can be linear upscaled. Thus, CuI coated on 3D spacer fabrics can be attractive to fabricate thermoelectric devices especially in the lower temperature range for textile medical or leisure applications.

Preparation and Properties of Flexible Cushioning Composites Based on Silicone Rubber and Warp—Knitted Spacer Fabric

This paper aims to develop a new type of flexible cushioning composite material that can be applied to cushioning protective appliances. Room temperature vulcanized silicone rubber (RTV silicone rubber) was filled into five groups of warp knitted spacer fabrics with different structural parameters, and flexible cushioning composites with filling rates of 30%, 50% and 70% were prepared. At the same time, there was a group of warp knitted spacer fabrics without silicone rubber as control. Then the infrared spectrum of silicone rubber was analyzed to test the compression and impact properties of flexible cushioning composite. It is found that the increase of filling rate enhances the compressive and impact properties of flexible cushioning composites. The flexible cushioning composite material can show better compression performance at a larger compression ratio. The structural parameters affecting the impact properties of flexible cushioning composites are arranged in descending order as fabric thickness, spacer tilt angle, spacer density, mesh number. The established mathematical model can provide a theoretical basis for the performance study of such composite materials. The compressive properties and impact properties of flexible buffer composites are not correlated.

Application of superabsorbent geotextiles to decontaminate and improve crude oil-contaminated soil

The contamination of soil by various oil products is a severe geo-environmental problem. In this study, some geotextiles were used as superabsorbent geotextiles to decontaminate soil polluted with crude oil. The ability of these geotextiles to absorb oil is better than that of absorbing water. The removal efficiency of the absorbent geotextile was first evaluated by placing the spacer fabrics in different arrangements in contaminated soil samples. Second, the shear strengths of the decontaminated soil samples were evaluated through a series of direct shear tests and compared with those of contaminated soil. The effects of crude oil content, vertical stress, and geotextile arrangement were thoroughly investigated to understand the vivid behavior of the specimen matrix. The results showed that the geometric properties of geotextile and sand, such as the mean size of sand particles, aperture size, fluffs, and piles of geotextile, geotextile roughness, and the two phases occurring in the specimens – wettability and saturation of absorbent layer – are vital in determining the sand-geotextile interface and the behavior of shear strength parameters of the matrix. Ultimately, the results confirmed the efficiency of absorbent geotextile as a potential method for controlling soil contamination and improving the shear strength parameters.