Friction Spinning Research Articles

Fibre waviness reduction in thermoplastic pultrusion by using DREF yarns

Non-reactive thermoplastic pultrusion impregnation issues are mitigated by using hybrid input materials. Co-wound (CW) and commingled yarns are an assembly of continuous polymer and reinforcement fibres. Continuous thermoplastic fibres have shown to induce waviness in the reinforcement fibres during pultrusion due to their shrinkage at high temperature. DREF yarns are composed of a core of continuous reinforcement fibres onto which discontinuous polymer fibres are applied using the friction spinning process. This study, based on the application of 3N and 0N tension on CW and DREF yarns, aimed to highlight the contribution of discontinuous polymer fibres on reducing reinforcement waviness in pultruded rods. CW yarns’ reaction to heating showed continuous polyethylene terephthalate (PET) fibres shrinkage resulting in wavy glass fibres (GF). Conversely, the GF in DREF yarns remained straight. Pultrusion experiments with yarn tension of 3N were done to alleviate the GF waviness. However, the porosity was rather high at 4.2% for CW rods and 2.3% for DREF rods. Pultrusion experiments without tension showed lower porosity of level of 2.9% for CW yarns and as low as 1.1% for DREF yarns. However, CT-scan image indicated GF waviness in CW rods. GF in DREF rods remained straight. The in-plane shear strength reached 119 MPa. Thermoplastic pultrusion using DREF yarns resulted in composites without reinforcement fibre waviness, lower porosity level and superior shear strength.

Multi-layer, torsional, highly-integrated yarn with outstanding orientation selective sensing ability for vertical-stress detected intelligent fabric

The multi-scale structure of yarns and fabrics is expected to provide unlimited possibilities for the integration of different performances and functions, which is expected to open up new opportunities for more complex and variable intelligent scenarios in the future. However, how to customize multi-functions through effective regulation and stabilization of several different units and composites in a highly integrated way still remains a great challenge. Herein, a torsional highly-integrated yarn with outstanding orientation selective sensing ability and robustness was achieved through a large-scale multi-unit friction spinning technology. Owing to the cooperative torsion structure of core layer (highly-stretchable spandex), middle layer (tight helical conductive metal wire) and the shell layer (polyester microfiber network massively composite with carbon nanotubes), the integrated yarn possesses outstanding orientation selective sensing ability. Different from directly coating strategies, the multilayer yarns with tight helical metal wire could be reversibly stretched up to 300 % with an almost consistent resistance (only varies 2.11 %), while which is highly sensitive to the vertical stress (5 kPa with 98.4 %) owing to the series–parallel behaviors between different layers. The sensitivity of the developed yarn in wind and sand monitoring and friction collision sensing endows it with a broad application prospect for protecting and early warning of human body and precision equipment. This work may provide a valuable integrated-solution for future intelligent fabric design for complex scenes.

Micromechanical Modelling of the Deformation Mechanisms of Friction-Spun Yarn from Recycled Carbon Fibres

The growing use of carbon fibre-reinforced polymers (CFRP) results in an increased amount of CF waste from offcuts or end-of-life components. A promising method to reuse the waste fibre materials in a structural component with excellent mechanical properties is the processing of recycled CF (rCF) and thermoplastic fibres into hybrid yarns. Spinning of friction spun yarns consisting of more than 90% rCF and containing almost no thermoplastic fibres that are suitable for thermoset composites, currently leads to high fibre damage and low yarn quality and is, therefore, addressed in this project. The technology is reported in another paper. One of the limiting factors for drapability of textiles is the stretchability of continuous fibres and draping of the semi-finished textile products for complex geometries is still error-prone. Friction spun yarns exhibit significantly higher yarn elongations due to sliding mechanisms between the fibres. The deformation properties of friction spun yarns are significantly influenced by fibre-fibre interactions and depend on a variety of process and material parameters. In the following, micromechanical finite element models of the spun yarns are created by using beam elements. Monte Carlo method is used to model local variabilities in the yarns. The models are then used to simulate yarn behaviour under deformation and to investigate the influence of various process parameters.

Friction spun spandex/rGO/Ag/polyester core-sheath yarn with antibacterial activity for wearable sensors

Wearable sensors, which feature textile substrates integrated with conductive layers, have received increasing attention from researchers due to their huge potential in health management. However, the inevitable damage of conductive layer caused by friction and bacterial growth on the textile substrate during its direct contact with bare skin are still the issues that hinder the long-term service of wearable sensors. Herein, a core-sheath yarn was prepared by wrapping polyester (PET) fibers coated with reduced graphene oxide (rGO)/silver nanoparticles (Ag NPs) around the spandex filaments via friction spinning. The core-sheath structure guarantees good prevention of the interface composed of rGO and Ag NPs in between from friction, while the introduction of Ag NPs ensures antibacterial activity of the yarn. The morphology and chemical composition of the nanomaterials deposited on the surface of PET fibers was investigated to reveal the sensing mechanism of the yarn. Meanwhile, its sensing performance was comprehensively evaluated from the perspectives of sensitivity, durability and comparison of commercial ECG. Despite the fact that inevitable damage of the rGO/Ag layer occurred during the friction spinning process, the core-sheath yarn still featured a gauge factor of 8.11 and a threshold of sensing range up to 68.57 %. Apart from being able to detect respiratory signals, cardio signals with the frequency of 70 beat per min (bpm) was also recorded. Compared to signals with the frequency of 73 bpm recorded by a commercial ECG sensor simultaneously, the core-sheath yarn exhibited satisfying precision. Moreover, the existence of Ag NPs in the conductive interface endowed the yarn with ability to yield 13-mm and 15-mm wide growth inhibition zones of E. coli and S. aureus, respectively. The cardiorespiratory sensing ability coupled with antibacterial activity of the yarn suggested its satisfying sensitivity and prolonged service time, making it a promising wearable sensor subjected to direct skin contact for long-time cardiorespiratory monitoring.

Development of yarns from recycled carbon fiber based on friction spinning technology with specific properties for thermoset composites

Because of a growing demand and usage of carbon fiber, effective methods to re-use waste and recycled carbon fiber recoverable either from process scraps or from end-of-life components are attracting increased attention. The development of different hybrid yarn structures consisting of recycled carbon fiber and thermoplastic fibers (recycled carbon fiber content approx. 50% by weight) for thermoplastic composites have been reported earlier. Yarns with high recycled carbon fiber content (>90% by weight) required for thermoset composites are still not realizable due to high shortening in recycled carbon fiber length (≥70%) during different processing steps of spinning. The reason lies in low shear strength, smooth fiber surface and high brittleness of recycled carbon fiber. Second, a lack of crimp in recycled carbon fiber leads to drafting errors during the drawing and spinning process. In this paper, the spinning limit regarding the core to sheath ratio of noble yarns with a recycled carbon fiber content greater than 90% by weight based on friction spinning technology for thermoset composites is reported. Slivers of recycled carbon fiber solely required for the development of yarns are produced on carding and drawing machines optimized for the gentle processing of recycled carbon fiber. Furthermore, different spinning parameters such as spinning drum speed and suction air pressure are investigated and their effect on tensile properties of yarn is analyzed. The results show that yarns with high recycled carbon fiber content (>90% by weight) can be produced with reproducible quality on the DREF-3000 friction spinning machine.

Large-scalable fabrication of zirconium carbide-based core-sheath yarn for wearable applications

As advances in science and technology highlight the applications of electronic textiles, their reliance on natural resources becomes apparent. To promote sustainability, yarns with strain-sensing and photothermal conversion functions are needed, utilizing recyclable resources effectively. However, current-sensing yarns with photothermal-conversion functions have low photothermal-conversion capabilities. Herein, we report a simple and feasible strategy for fabricating core-sheath-structured yarns with photothermal and sensing capabilities for photothermal conversion and strain-sensing applications. The spinning speed employed in the friction spinning approach exceeded 600 m/h, paving the way for a new method that combines sensing and photothermal properties. The multi-layer yarn included spandex as the core yarn, carbon nanotube-coated cotton as the middle layer, and a zirconium carbide@polyurethane film as the sheath. The obtained spandex/carbon nanotube @cotton/zirconium carbide@polyurethane yarn had good strain sensing ability, and the yarn temperature could be increased to 103.5 °C after 1 min of infrared-light irradiation, being stabilized at 121.7 °C after 5 min. The durability tests demonstrated that the sensing and photothermal capabilities of the yarns were maintained well after cyclic performance test, cyclic friction test and cyclic twist test. The obtained core sheath yarn may provide a feasible way for industrial-scale manufacture wearable electronic devices and smart sensing yarn with excellent sensing and photothermal performance.

Liquid flow spinning mass-manufactured paraffin cored yarn for thermal management and ultra-high protection

Thermal management and ultra-high protection textiles are critical for polar scientists, astronauts and firefighters. Phase change materials (PCMs) effectively retard huge thermal changes, and thermal damage by absorbing or releasing heat during phase transition. However, due to the materials and engineering challenges inherent in PCMs based textiles, commercial PCMs usually suffer with high rigidity, no-breath-ability, easy leakage and abrasion, limiting their potential applications. Herein, we proposed a mass-producible liquid flow spinning (LFS) method, in which molten paraffin is poured into continuous hollow silicon tubes and then wrapped by staple fibers to form paraffin-coated yarns (PCYs) on a friction spinning frame. The obtained PCYs showed enhanced mechanical properties (break strength of 7.80 N, wear resistance of 2000 cycles) due to the novel core-sheath yarn structure. Besides, thanks to the high melting enthalpy (60.967 J/g) of PCYs, the yarns showed the excellent temperature regulating effect. A double-sided joint PCYs fabric (PCYF) is fabricated to study the PCYs performance further, results show that the PCYF can withstand 10,000 cycles of abrasion without breakage and PCMs leakage. Furthermore, owing to the much gaps provided by the stretch fibers and interweaving points, the fabric exhibits good breathability. In particular, compared with commercial PCMs based textiles, our PCYF is superior in thermal protection performance (9 °C lower). The fireproof performance is also excellent as our PCYF can withstand flame temperatures higher than 1142 °C. The PCYs production method provided here could pave the way for human thermal protection textiles.

Scalable Fabrication of an MXene/Cotton/Spandex Yarn for Intelligent Wearable Applications

Wearable sensors based on MXene have attracted attention, but the large-scale production of MXene-based textile materials is still a huge challenge. Hereby, we report a facile way of incorporating MXene into the traditional yarn manufacturing process by dipping and drying MXene into cotton rovings followed by fabricating an MXene/cotton/spandex yarn (MCSY) using friction spinning. The MXene in the MCSY brings electrical conductivity to the MCSY with well-preserved mechanical properties. Due to its wide sensing range from 408 Pa to 10.2 kPa, the MCSY can be used to monitor human motions in real time, such as writing, walking, and wrist bending. In addition, the MCSY exhibits a stable compression sensing performance even under different strains. Furthermore, the MCSY can be sewn into clothing or onto a mask as an embroidery pattern to develop sensing device prototypes capable of detecting touching or breathing. The reported manufacturing technology of the MCSY will lead to an industrial-scale development of MXene-based e-textiles for wearable applications.

Hierarchical and coaxial yarn with combined conductance stability and sensing capability for wearable electronics

Yarn-based sensors are essential units for smart textiles and wearable devices. Most reported fiber sensors, however, are sensitive or stable in conductivity under stretching, limiting their applicability. Herein, we report a strategy for fabricating a specific sensor based on liquid metal/tube/CNT polyester yarn (LTCPY) via friction spinning. The inside of the multilayer composite yarn served as a wire with a broad strain range (0%–300%) and ultrahigh conductivity (3.78 × 105 S/m). The conductivity of the yarn remains at a relatively high level when it is stretched to 250% strain. The external structure endows the sensor with good sensing performance (GF of 6.73 under an elongation of 175%-203%) and recoverability (1000 cycles). The combination of conductance stability and good sensing properties contributes to the application potential of LTCPY as portable conductive wires, stretchable heaters, and wearable sensors to monitor human activities. Moreover, LTCPY can be easily woven into fabrics, introducing a new strategy for the mass production of electronic textiles.

Mechanical Properties of Flax-Polypropylene Composites from Dry Flexible Towpregs: Influence of Radial Position of Flax Fibers in the Towpreg

ABSTRACT The radial position of the flax fibers as reinforcement and polypropylene (pp) fibers as matrix was altered using friction spinning in three distinctive sequences from core to sheath, namely, (a) pp-flax-flax-pp (PFFP), (b) flax-pp-flax-pp (FPFP), and (c) flax-flax-pp-pp (FFPP). Interestingly, at the towpregs stage, PFFP demonstrated higher tensile characteristics than FPFP and FFPP. The towpregs were consolidated to yield three unidirectional composites (UDCs), namely, UDC-PFFP, UDC-FPFP, and UDC-FFPP, using compression molding. The tensile strength of the composites () was contrary to the breaking load (f) of the corresponding towpregs () which necessitated the current investigation. Remarkably, the UDC with the lowest tensile as well as interlaminar shear strength i.e. UDC-PFFP, yielded the maximum energy absorption in Charpy and Notch impact tests. In the towpreg, the flax fibers when placed at the core position, slid over each other resulting in poor strength in FFPP while post-curing the pp matrix impregnated the core flax fibers in UDC-FFPP, resulting in the highest strength amongst the three UDCs in tensile and flexural modes. Micro-computed tomography (µCT) was carried out to confirm the same. Thus, the user can select the requisite fiber-matrix radial positions within towpreg to suit the ultimate applications.

Further Development of an Adaptive Joining Technique Based on Friction Spinning to Produce Pre-Hole-Free Joints

Mechanical joining processes are an essential part of modern lightweight construction. They permit materials of different types to be joined in a way that is suitable for the loads involved. These processes reach their limits, however, as soon as the boundary conditions change. In most cases, these elements are specially adapted to the joining point and cannot be used universally. Changes require cost-intensive adaptation of both the element and the process control, thus making production more complex. This results in high costs due to the increased number of auxiliary joining element variants required and reduces the economic efficiency of mechanical joining. One approach to overcoming this issue is the use of adaptive auxiliary joining elements formed by friction spinning. This article presents the current state of research on pre-hole-free joining with adaptive joining elements. The overall process chain is illustrated, explained and analyzed. Special attention is paid to demonstrating the feasibility of pre-hole-free joining with adaptive joining elements. The chosen mechanical parameters are subsequently listed. Finally, a comprehensive outlook of the future development potential is derived.

Fabrication of cotton/polyethylene glycol/stainless steel wire friction spun composite yarn and its application in electrothermal phase change textile

This work successfully fabricated a textile with phase change and electrothermal function using a novel method. First, a core-sheath-structure composite yarn (cotton/polyethylene glycol/cotton/stainless steel wire) was prepared through friction spinning and sizing. Secondly, the composite yarn was weaved with 2-ply cotton yarns to form an electrothermal phase change textile. The resulting composite fabric possesses good phase change reliability after 50 heating/cooling cycles and exhibits great electrothermal repeatability after 50-cycle durability test. The addition of polyethylene glycol can increase the maximum surface temperature of the fabric (e.g., the highest temperature of the fabric can reach 66 °C when the voltage is 5 V, while the highest temperature of the blank sample is 56 °C), extend the heat time of composite fabrics, alleviate dramatic temperature fluctuations while charging and discharging, and improve the surface temperature distribution uniformity of the fabric. The described method displays a new platform for developing electrothermal heating elements utilized in flexural heaters, medical electrothermal, and defrosting.

Fabrication and characteristics of polyethylene glyco/cotton friction spun composite yarn

This paper focused on the preparation and performance analysis of a series of friction-spun composite yarns with phase change function. We firstly prepared a core yarn (polyethylene glycol/cotton) through sizing method, and then made seven composite yarns with different sheath materials and spinning drums speeds by friction spinning. Finally, the study explored the effects of spinning drums speeds and sheath fibers on morphology, yarn strength, and thermal properties of friction-spun composite yarns. The yarns whose shell material is terylene and spinning drums speed is 8000 r/min or 9000 r/min were optimized. The results show that terylene/polyethylene glycol/cotton yarn has the tightest wrapping state, while wool/polyethylene glycol/cotton has the loosest wrapping state. Besides, yarn strength increases by 66% after sizing PEG. The enthalpy efficiency of the yarn reaches up to 56%, whose melt peak is at 59.58 °C and the corresponding latent heat is 114.33 J/g. Such a structure and manufacture method make it easy to replace the raw materials in the yarn, so the temperature and thermal storage property of the yarn is adjustable, suggesting great potential for application in energy storage and thermo-regulation products.

A contribution on versatile process chains: joining with adaptive joining elements, formed by friction spinning

Nowadays, manufacturing of multi-material structures requires a variety of mechanical joining techniques. Mechanical joining processes and joining elements are used to meet a wide range of requirements, especially on versatile process chains. Most of these are explicitly adapted to only one, specific application. This leads to a less flexibility process chain due to many different variants and high costs. Changes in the boundary conditions like sheet thickness, or layers, lead to a need of re-design over the process and thus to a loss of time. To overcome this drawback, an innovative approach can be the use of individually manufactured and application-adapted joining elements (JE), the so-called Friction Spun Joint Connectors (FSJC). This new approach is based on defined, friction-induced heat input during the manufacturing and joining of the FSJC. This effect increases the formability of the initial material locally and permits them to be explicitly adapted to its application area. To gain a more detailed insight into the new process design, this paper presents a detailed characterization of the new joining technique with adaptive joining elements. The effects and interactions of relevant process variables onto the course and joining result is presented and described. The joining process comprises two stages: the manufacturing of FSJC from uniform initial material and the adaptive joining process itself. The following contribution presents the results of ongoing research work and includes the process concept, process properties and the results of experimental investigations. New promising concepts are presented and further specified. These approaches utilize the current knowledge and expand it systematically to open new fields of application.

‘Effect of yarn composition and fabric weave design on microwave and EMI shielding properties of hybrid woven fabrics’

Ring spun composite yarn (RCY; 755 denier) with linear resistance of 172 Ω/m is prepared with stainless steel (SS) fibre and polyester fibre in ratio of 80%: 20% (w/w). Sheath core yarn system, core being ring spun yarn and PET fibre as sheath material is prepared in various fibre compositions adopting friction spinning technique. For microwave interaction and EMI shielding, hybrid woven fabrics are prepared using sheath-core yarn in weft and SS/PET blended yarn (20% SS/80% PET) in warp in cell structured and rib structured weave design. Samples of woven fabric were evaluated for microwave and EMI shielding properties in frequency range of 8.2–18.0 GHz in parallel and perpendicular polarisation of electromagnetic wave (em wave). Samples having conducting yarn in warp and weft both have shown high reflection in both polarisation of em wave. Sample containing metal fibre content of 32.58% (w/w) prepared in cell-structured weave design containing 1330 and 2017 denier sheath-core yarn in weft and 165 denier (20% SS/80% PET) blended yarn in warp offered reflection of 89.4922–59.9864% in parallel mode and 92.8135–80.0789% in perpendicular mode. This offered EMI shielding of −30.9601 to −35.4659 dB in perpendicular and −17.0209 to −11.2131 dB in parallel mode in 8.2 − 18.0 GHz. Woven fabrics are highly breathable, its air permeability lies in the range of 22.5–26.2 ft3/ft2/s. It inherits high aesthetic values. This hybrid woven fabric finds potential applications in radar camouflage, protection of human being from hazardous effect of microwaves, EMI shielding and electrostatic discharging cover materials, etc.

Joining with versatile joining elements formed by friction spinning

Mechanical joints are an essential part of modern lightweight structures in a broad variety of applications. The reason for this is the rapidly increasing number of different material combinations needing to be joined in areas of application like the automotive industry. It is currently common to use numerous standardized elements (if necessary, from different joining technologies) instead of individually adapted joining elements. This leads to a large number of different joining elements per product and thus to high costs.An innovative approach to overcome this issue is the design and manufacturing of application adapted joining elements. A promising strategy for the manufacturing of adapted joining elements of this type is the so-called friction spinning process. The joining elements formed in this way can be specifically adapted to the application in question in terms of shape and mechanical properties. The joining process using this friction spun joint connectors (FSJC) benefits from the use of friction-induced heat and supports the process by reducing the joining forces required through a variation of the rotational speed and the feed-rate. By controlling the significant process parameter (e.g. the joining force), it is possible to substantially influence the quality of the joint or the joint properties. The following contribution will present results of ongoing research at Paderborn University and includes the process concept, the process properties, the tooling and the results of the experimental investigations of the joining of two preholed sheet metal parts with help of this new joining process.

Friction-Induced Recycling Process for User-Specific Semi-Finished Product Production

Modern forming processes often allow today the efficient production of complex parts. In order to increase the sustainability of forming processes it would be favorable if the forming of workpieces becomes possible using production waste. At the Chair of Forming and Machining Technology of the Paderborn University (LUF) research is presently conducted with the overall goal to produce workpieces directly from secondary aluminum (e.g., powder and chips). Therefore, friction-based forming processes like friction spinning (or cognate processes) are used due to their high efficiency. As a pre-step, the production of semi-finished parts was the subject of accorded research work at the LUF. Therefore, a friction-based hot extrusion process was used for the full recycling or rework of aluminum chips into profiles. Investigations of the recycled semi-finished products show that they are comparable to conventionally produced semi-finished products in terms of dimensional stability and shape accuracy. An analysis of the mechanical properties of hardness and tensile strength shows that a final product with good and homogeneously distributed properties can be produced. Furthermore, significant correlations to the friction spinning process could be found that are useful for the above-mentioned direct part production from secondary aluminum.

Precision Manufacturing of a Linear Fiber Assembly with Axially Varying Compositions and Structures by Using Computer Numerically Controlled Ring Spinning

Ring spinning is an effective technology for forming multi-component spun yarns. There is an increasing need for multifunctional textiles with characteristics, such as antibacterial properties, UV protection, easy cleaning, and color alteration, which can be achieved via various physical and mechanical processing approaches, such as electrospinning, friction spinning, hollow spindle spinning, and ring spinning. In particular, ring spinning is based on the mechanical processing of fibers, and it is suitable for mass customized production systems. However, conventional ring spinning involves a fixed fiber blending ratio and yarn linear density, which limits its usefulness for fabricating multifunctional textiles due to the uncontrollable composite yarn structure. In the present work, we propose a new method for manufacturing a three-component spun yarn by combining a computer numerical control system with a ring spinning frame, which increases the flexibility of yarn production. The as-prepared composite yarns possess axially varying compositions and structures, which can be readily tuned by changing the feeding speeds of the back rollers, and these aspects can facilitate the fabrication of multifunctional textiles for mass production at a low cost. To the best of our knowledge, this is the first work to demonstrate the feasibility of fabricating a three-component spun yarn with tunable compositions and structures by employing a ring spinning frame.

Electro-mechanical characterization of shape memory alloy hybrid yarn based adaptive fiber-reinforced plastics

Shape memory alloys (SMA) are being used for the development of adaptive fiber-reinforced plastics (FRP) with high functional density. During the thermal induced activation of SMA, a barrier layer between FRP matrix and SMA is necessary to reduce the delamination at the interface between them and increase the deformation potential of FRP by mechanical decoupling of SMA from the matrix. Hence, this work presents the electro-mechanical characterization of adaptive FRP that are based on SMA hybrid yarns. To realize this aim, four types of SMA hybrid yarn variations were produced by means of the friction spinning technology. Subsequently, these SMA hybrid yarns were integrated into reinforcing fabrics by tailored fiber placement technology for the fabrication of adaptive FRP. In the final step, extensive electro-mechanical characterizations of the produced hybrid-yarn-based adaptive FRP were performed. Results revealed that the type of SMA hybrid yarn significantly influenced the deformation behavior of adaptive FRP.

Influence of composite architecture and interfacial bonding on their impact properties

Resistance to impact thrust is one of the most important requirement along with many others for defining suitable applications of any composite materials. In this present work, the influence of composite architecture and composite interfacial bonding strength on the impact performance of flax reinforced PP composites have been investigated. In this regard two different composite architecture through conventional film stacking method and through DREF (DR. E. Fehrer open-end friction spinning process) yarn consolidation method have been produced and to alter the fibre–matrix interfacial bonding the flax fibres are treated with MAgPP (Maleic Anhydride grafted Polypropylene). Finally, the notch Izod impact behaviour of all composite samples are evaluated and compared.