Polyurethane Fibers Research Articles

Development and Application of a Test System for Modeling Tunnel Excavation with Transparent Rock Surrogate

Abstract Physical modeling using transparent rock or soil surrogates and optical measurement is an effective way to obtaining the displacement and stresses within test specimens in geotechnical engineering. To apply the prospective modeling method to investigating the mechanism of excavation-induced failure of rock surrounding tunnels, a novel test system is developed for modeling tunnel excavation with transparent rock surrogate. The system includes three parts: one transparent acrylic chamber and its reinforcing units for containing scaled models, a dead-weight loading device consisting of levers and pulleys, and a three-dimension optical stressometer made of polyurethane block and fiber Bragg gratings. The test system is then employed to visualize the excavation of a round tunnel and some favorable results are gained. To some extent, the work in this article improves the physical modeling techniques and provides an effective method for the modeling research in rock tunnel engineering.

Fabrication and characterization of electrospun polyurethane blended with dietary grapes for skin tissue engineering

The tissue-engineered skin has emerged as a plausible alternative approach to the traditional wound dressing owing to its inherent advantages. Further, in tissue engineering applications, fibrous scaffold obtained through textile technologies is widely attractive. The present study focused on the fabrication of electrospun textile polyurethane wound dressing scaffold incorporated with grape extract. The fabricated composites showed smooth as well as reduced fiber (730 ± 127 nm) and pore (873 ± 51 nm) diameter than the control polyurethane (fiber diameter –890 ± 117 and pore diameter –1064 ± 74 nm) as revealed in the scanning electron microscopy. The formation of hydrogen bond in Fourier transform infrared spectroscopy revealed the interaction between the polyurethane and grape. The addition of grape enhanced the wettability behavior (86° ± 2) and the surface roughness (469 nm) of the polyurethane membrane. Thermal gravimetric analysis and mechanical testing revealed the enhancement of thermal and tensile strength with the incorporation of the grape into the polyurethane matrix. The in vitro blood compatibility and cytocompatibility studies revealed enhanced antithrombogenicity behavior and the non-toxic nature to human dermal fibroblast cells for the fabricated composites than the pristine polyurethane. Hence, the addition of grape into the polyurethane matrix had enhanced the physicochemical characteristics and biocompatibility parameters which could promote this candidate as a valid alternative for skin tissue engineering regeneration.

Kurkumin Yüklü Biyo-Bazlı Elektroeğirme Poliüretan Yapılar

Polymeric electrospun fibers present well-design scaffolds for wound healing applications. Here, the fabrication of biobased polyurethane (PU) blend fibers containing curcumin (Cur) was reported. Not only polymer concentration but also curcumin concentration affects the morphology, diameter, and contact angle values of the fibers. Morphological investigations revealed that the diameter and hydrophilicity of the PU fibers increased upon addition of curcumin. Effect of process parameters (applied voltage, flow rate, and tip-to-collector distance) on the average diameter and the hydrophilicity of the PU and PU/Cur fibers were examined. Optimum conditions to obtain uniform and bead-free PU/Cur fibers were determined as 12.5 kV, 1 mL/h, and 17 cm. This study demonstrates that the electrospinning process provides a simple way of obtaining bioactive agent loaded fibrous scaffolds, as well as contributing to a better understanding of the effect of process variables in the fabrication of PU/Cur blend fibers for wound healing applications.

Design of polyurethane fibers: Relation between the spinning technique and the resulting fiber topology

ABSTRACTProperties or characteristics of fibers are affected by their topology. In fact, these topologies are found to have significant impacts in the functionalities of many applications. Hence, in this study, the relations between the spinning techniques and the topology of the resulting fibers are studied with the aim to provide a guideline for future reference where fibers with certain topology can be fabricated to suit specific applications. For this purpose, polyurethane is chosen to be the raw material to fabricate the fibers due to its versatility to be applied in various fields. The surface morphology, structures, and alignments of the fibers are studied. It is found that the polymer solution properties largely influence the mechanisms in the spinning process and can significantly affect the topology of the fibers. For instance, viscous solutions enable the spinning of coiled and smooth fibers, whereas conductive solutions encourage the splaying of the solution jet which results in the spinning of straight fibers. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47706.

The mineralization of polymer electrospun fibrous membranes modified with tourmaline nanoparticles

Abstract

Augmented physico‐chemical, crystalline, mechanical, and biocompatible properties of electrospun polyurethane titanium dioxide composite patch for cardiac tissue engineering

Although there is enormous growth in the technology for cardiovascular applications, remodeling of the damaged cardiac tissue is still a daunted task. Polymeric scaffold could be able to regenerate the human cardiomyocytes which facilitate the remodeling of the cardiac damage. The objective of the study is to fabricate polyurethane (PU) cardiac patch added with titanium dioxide (TiO2) nanofibers using electrospinning technique. The morphological investigation demonstrated the reduced fiber (666 ± 155 nm) and pore diameter (862 ± 75 nm) of the fabricated nanocomposite compare with the pristine PU (fiber diameter – 890 ± 117 nm and pore diameter – 1,064 ± 74 nm). Field emission scanning microscopy (FESEM), infrared (IR) spectrum, and thermal analysis confirmed the existence of titanium dioxide in the pristine PU. The wettability study showed the hydrophobic behavior (109° ± 1.53°) of electrospun PU/titanium dioxide nanocomposites than the pristine PU (100° ± 0.58°). X‐ray diffraction (XRD) study denoted the crystalline behavior of the pristine PU with the addition of titanium dioxide. Tensile (19.48 MPa) and surface (425 nm [Ra]) testing indicated that the addition of titanium dioxide improved the mechanical and surface roughness of the pristine PU (tensile strength – 7.12 MPa and roughness – 313 nm). The coagulation and cytotoxicity study depicted the enhanced anticoagulant behavior and improved cell viability of the developed nanocomposites than the PU. Hence, the developed novel patch exhibiting better physico‐chemical characteristics, enhanced blood compatibility parameters, and good cell viability rates hold to be a promising candidate for cardiac tissue repair. POLYM. COMPOS., 40:3758–3767, 2019. © 2019 Society of Plastics Engineers

Recent Advances in Applications of Acidophilic Fungi to Produce Chemicals.

Processing of fossil fuels is the major environmental issue today. Biomass utilization for the production of chemicals presents an alternative to simple energy generation by burning. Lignocellulosic biomass (cellulose, hemicellulose and lignin) is abundant and has been used for variety of purposes. Among them, lignin polymer having phenyl-propanoid subunits linked together either through C-C bonds or ether linkages can produce chemicals. It can be depolymerized by fungi using their enzyme machinery (laccases and peroxidases). Both acetic acid and formic acid production by certain fungi contribute significantly to lignin depolymerization. Fungal natural organic acids production is thought to have many key roles in nature depending upon the type of fungi producing them. Biological conversion of lignocellulosic biomass is beneficial over physiochemical processes. Laccases, copper containing proteins oxidize a broad spectrum of inorganic as well as organic compounds but most specifically phenolic compounds by radical catalyzed mechanism. Similarly, lignin peroxidases (LiP), heme containing proteins perform a vital part in oxidizing a wide variety of aromatic compounds with H2O2. Lignin depolymerization yields value-added compounds, the important ones are aromatics and phenols as well as certain polymers like polyurethane and carbon fibers. Thus, this review will provide a concept that biological modifications of lignin using acidophilic fungi can generate certain value added and environmentally friendly chemicals.

Effect of MWCNT content on the mechanical and strain-sensing performance of Thermoplastic Polyurethane composite fibers

Stretchable conductive fibers have attracted significant attention due to their ability to be directly woven into or stitched onto fabrics, making them ideal for use in the design of integrated wearable strain sensors. Here, we report on a highly stretchable multi-walled carbon nanotube (MWCNT)/Thermoplastic Polyurethane (TPU) fiber produced via a wet spinning process. The effects of MWCNT content and alignment on the structural, mechanical, electrical and strain-sensing properties of the composite fibers were investigated. The highest conductivity (6.77 S cm−1), tensile strength (28 MPa) and maximum elongation at break (565%) were obtained by controlling the MWCNT content. Gauge factor (GF) values were also affected by the content and MWCNT alignment in the composite fibers, as these parameters determine the change in the effective contact area and number of conductive paths available during stretching. The well-aligned MWCNT/TPU fiber showed a high GF value of 5200. Wearable strain sensors capable of obtaining real-time mechanical feedback for various human motion detections with different GFs and working strain ranges could be realized by controlling the MWCNT concentrations in the TPU matrix.

Investigation of Composite Nano Air Filter for Improving Antimicrobial Activity and Reducing VOCs Using a High Speed Upward Electrospinning System.

A new nano air filter for fine dust filtration with antibacterial and volatile organic compounds (VOCs) adsorption properties was fabricated using a bottom-up, high-speed electrospinning system. To optimize production, polyurethane fibers were electrospun at various voltages on polypropylene nonwoven fabrics, and results show that fiber diameter decreased as voltage increased. Silver nanoparticles (AgNPs) and Activated Carbon (AC) were used as antimicrobials and VOC-reducing agents. FTIR, SEM, and EDS were performed to analyze the resulting filter fabricated by electrospinning. FTIR and EDS results show that the AgNPs and activated carbon added to the PU fibers were successfully integrated into the PP nonwoven fabric.

Blood-compatible Polyaniline Coated Electrospun Polyurethane Fiber Scaffolds for Enhanced Adhesion and Proliferation of Human Umbilical Vein Endothelial Cells

The endothelialization and anti-thrombotic abilities of tissue engineered vascular scaffolds are considered to be effective properties for improving the performance small-caliber vascular scaffolds. For this purpose, we designed and developed electrically conductive fibrous scaffolds based on polyaniline coated polyurethane (PANI-PU) electrospun fibers for vascular tissue engineering applications. The porosity of PANI-PU fibers was 75.27±2.04 %. The obtained PANI-PU fibers were characterized by SEM observations, XPS analysis, water contact angle (WCA) measurement and mechanical property. The PANI functionalization aimed to improve the performance of anticoagulation and endothelialization. The WCA of PAIN-PU decreased to 35° from 135° of PU fibers. Blood compatibility and cytocompatibility were compared before and after PANI coating. The adhered platelet cells on PANI-PU was 6.87×105/cm2 and plasma recalcification time was 123 s. Platelet adhesion and plasma recalcification time test showed that the PANI-PU scaffolds had a certain anticoagulant effect. The hemolysis rate of PANI-PU fibers was 0.14 %, which showed that the PANI-PU scaffolds could be used as blood contact materials. The observation of endothelial cell proliferation and morphology in human umbilical vein endothelial cells showed that PANI-PU fibers were more beneficial to cell adhesion, proliferation and extension than that of PU fibers. The results demonstrates the PANI coated electrospun PU fibers have great potential in application as small-diameter vascular grafts and this work shows new insights into conductive scaffolds for vascular tissue engineering.

Electrospun polyurethane fibers doped with manganese oxide nanoparticles as an effective adsorbent for determination of priority pollutant mono-nitrophenols in water samples

Nitrophenols (NPs) are carcinogenic and high toxic compounds, which contaminate surface water, groundwater and soil with serious effects on human health. The polyurethane-manganese oxide (PU-MnO) composite nanofibers were fabricated by electrospinning and used as an adsorbent for extraction of priority pollutants mono-nitrophenols. The presence of the manganese oxide nanoparticles in the adsorbent matrix showed synergistic effects on extraction efficiencies of mono-nitrophenols. A green headspace-solid phase microextraction (HS-SPME) method using the novel adsorbent coupled with gas chromatography-micro-electron capture detection (GC-μECD) was developed for the determination of the selected nitrophenols. The main parameters of the extraction method were investigated and optimized. The figures of merit obtained under optimal conditions were as follow: the linear dynamic range, 0.100–5.00 × 102 ng/mL; the relative standard deviations (RSD, n = 3), 2.53–11.2%; and the limits of detection, 0.0201, and 0.138 ng/mL. The relative recoveries for real samples (river water and wastewater) were between 90.3 and 105%. Therefore, the developed nano adsorbent and the proposed eco-friendly analytical method were utilized successfully for extraction of mono-nitrophenols in real water samples.

Dyeing of Polyurethane Fibers with Traditional Classes of Dyes

A new method consisting of diazotization followed by azo coupling with azotol is proposed for dyeing polyurethane fibers. Unlike traditional methods, the new method does not require high temperatures and long treatment times. The effect of external factors on the intensity and fastness of the dyes obtained by the new method was examined, the reflectance spectra were obtained, and the K/S relations of dyed samples of polyurethane were calculated.

Highly stretchable multi-walled carbon nanotube/thermoplastic polyurethane composite fibers for ultrasensitive, wearable strain sensors.

Here, we report a novel highly sensitive wearable strain sensor based on a highly stretchable multi-walled carbon nanotube (MWCNT)/Thermoplastic Polyurethane (TPU) fiber obtained via a wet spinning process. The MWCNT/TPU fiber showed the highest tensile strength and ultra-high sensitivity with a gauge factor (GF) of approximately 2800 in the strain range of 5-100%. Due to its high strain sensitivity of conductivity, this CNT-reinforced composite fiber was able to be used to monitor the weight and shape of an object based on the 2D mapping of resistance changes. Moreover, the composite fiber was able to be stitched onto a highly stretchable elastic bandage using a sewing machine to produce a wearable strain sensor for the detection of diverse human motions. We also demonstrated the detection of finger motion by fabricating a smart glove at the joints. Due to its scalable production process, high stretchability and ultrasensitivity, the MWCNT/TPU fiber may open a new avenue for the fabrication of next-generation stretchable textile-based strain sensors.

Development of natural fibre for environmental and sustainable advancement

The increasing attention on renewable resources for a sustainable environment has led to the expansion in the development of high-performance products made from natural resources. Natural fibres that are diffused in the environment in abundance are economical, making this characteristic a value-added engineering, as they exhibit lower cost and can produce lighter composites, as compared to the existing fibreglass reinforced polymer composites. In this study, the involvement of kenaf fibre in chemical treatment on morphological and mechanical properties of the thermoset polyurethane (PU)-(PUKf) composites was firstly proposed and trialled. The results of chemical treatment on kenaf fibre highlight the improvement on the impact strength although the hardness of kenaf composites is reduced. This is compared with different samples, which are pure thermoset PU and kenaf fibre without chemical treatment. Overall, the developments of natural fibre in engineering and energy sectors could significantly enhance the reduction of solid waste and environmental pollution.

A flexible smart membrane consisting of GO composite fibres and upconversion MSNs for microRNA detection.

We have developed a photoluminescent membrane for microRNA detection, consisting of chemically modified mesoporous silica nanoparticles (CaF2:Yb/Ho@MSNs) attached, via single stranded DNA probes, to flexible polyurethane fibres coated with graphene oxide (GO). By detecting the release of the luminescent nanoparticles resulting from complementary co-hybridization between target miRNA sequences and the DNA probe, accurate measurements of the miRNA concentration at high sensitivity levels can be obtained. The constructs therefore offer a route to rapid detection and the potential for early cancer diagnosis.

Preparation and structure of rare earth/thermoplastic polyurethane fiber for X‐ray shielding

ABSTRACTRare earth/polypropylene (PP)/thermoplastic polyurethane (TPU) fibers were prepared by melting spinning with different mass ratios of PP to TPU. Then the rare earth/TPU shielding fiber was obtained by removing the PP matrix phase from the blend fiber using xylene. The fibers were characterized by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), X‐ray diffraction (XRD), thermogravimetric analyzer (TG), and scanning electron microscopy (SEM). Short fibers were compression‐molded for the test of lead equivalent. The results showed that the lead equivalent of the rare earth/TPU composite fibers was 0.19 mmPb when the mass ratio of PP/TPU increased to 60/40. At this mass ratio, the X‐ray shielding performance of the fiber was the best. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47435.

Tailorable and Flexible Conducting Films via Interfacial Modification of Polymer Fibers

AbstractPortable devices have become lightweight, flexible, and even stretchable such that skin‐like electronics are widely applicable, including in biomedical devices, soft robotics, and human/machine interfaces. Rendering these devices soft and flexible is highly desirable, as this would enable them to interact seamlessly with human skin and improve their wearing comfort. We demonstrate a convenient but effective method to fabricate flexible conducting films. These films consist of electrospun polyurethane (PU) fibers as the flexible substrate onto which copper was deposited. These Cu‐PU films have excellent conductivity, and their resistance only increases slightly after extensive folding, even when folded into a paper crane with a resistance of 1.8 Ω. Furthermore, Cu‐PU films can sense tension strength and exhibit stable Joule electrothermal performance. The Cu‐PU‐based heating glove could be heated to 40 °C in 30 s by applying 2 V. The simple but effective procedure presented here is suitable to fabricate flexible conducting film and may also promote the development of portable and flexible electronic products.

Characterization of composites based on polyoxymethylene and effect of silicone addition on mechanical and tribological behavior

Additives to polymer materials allow to obtain a wide range of functional properties. The improvement of wear and durability of plastics is achieved by the use of powder or fibrous fillers and complex modifications of structure. The aim of the work was to examine the physical, mechanical and tribological properties of modified polyacetal. As a modifiers various types of silicon, thermoplastic polyurethane and aramid fiber were used. The addition of above mentioned additives reduces the coefficient of friction and the wear rate in relation to pure polyoxymethylene, moreover used additives increase the strength properties. Studies have shown that the addition of filler allows to provide excellent tribological properties while maintaining high strength properties. POLYM. ENG. SCI., 59:935–940, 2019. © 2018 Society of Plastics Engineers

Processable Thermally Conductive Polyurethane Composite Fibers

AbstractThe demand for wearable electronics has resulted in an increasing interest in the development of functional fibers, with a specific focus upon the development of electrically conductive fibers incorporable into garments. However, the production of thermally conductive fibers for heat dissipation has been largely neglected. Owing to the very rapid development of miniaturized wearable electronics, there is an increasing need for the development of thermally conductive fibers as heat sinks and thermal management processes. In this study, thermally conductive but electrically insulating boron nitride nanopowder (BNNP) fillers are used to effectively enhance the thermal conductivity and mechanical properties of elastomeric polyurethane fibers. Thermal conductivity enhancement of more than 160% is achieved at very low loadings of BNNP (less than 5 wt%) with an improvement in the mechanical properties of the unmodified fiber. These thermally conductive fibers are also incorporated into 3D textile structures as a proof of processability.

Enriched mechanical, thermal, and blood compatibility of single stage electrospun polyurethane nickel oxide nanocomposite for cardiac tissue engineering

Electrospinning is a versatile technique for producing nanocomposite in biomedical applications. In this study, polyurethane (PU) cardiac patch loaded with nickel oxide (NiO) was fabricated using electrospinning technique. The morphology study revealed that the PU/NiO nanocomposites exhibited reduced fiber diameter (758 ± 157.10 nm) and pore diameter (868 ± 73.26 nm) compared to the pristine PU (fiber diameter 890 ± 116.91 nm and pore diameter 1064 ± 74.31 nm). The contact angle study indicated the decreased wettability behavior of the electrospun nanocomposite (106° ± 0.58°) than the pure PU (100° ± 0.58°). The incorporation of NiO into PU improved the mechanical strength (15.25 MPa) and surface roughness (448 nm) of the pristine PU (tensile strength 7.12 MPa and surface roughness 313 nm). The developed PU/NiO nanocomposites showed delayed blood clotting time and low hemolytic percentage as revealed in the coagulation studies insinuating the improved anticoagulant nature compared to the pristine PU. Moreover, 3‐(4,5‐dimethylthiazol‐2‐yl)‐5‐(3‐carboxymethoxyphenyl)‐2‐(4‐sulfophenyl)‐2H‐tetrazolium, inner salt (MTS) assay demonstrated the nontoxic behavior of fibroblast cells in the developed nanocomposite (135 ± 1%) than the pristine PU (133.33 ± 8.96%). The newly developed nanocomposite patch rendered better physicochemical, improved blood compatibility, and nontoxic to the fibroblast cells. Hence, the electrospun PU/NiO nanocomposite might serve as a plausible scaffold for the cardiac tissue engineering. POLYM. COMPOS., 40:2381–2390, 2019. © 2018 Society of Plastics Engineers