Polyurethane Fibers Research Articles

Elastic antibacterial membranes comprising particulate laden fibers for wound healing applications

ABSTRACTMedicated skin care products are available in various forms; ranging from lotions and creams to bandages and membranes. In this study, antibacterial particulate laden fibrous membranes (FMs) were prepared via electrospraying of tetracycline hydrochloride‐loaded poly(ε‐caprolactone) particles alongside electrospinning of thermoplastic polyurethane (TPU) fibers, through which both mechanical and biological aspects of a complete membrane system can be achieved. Random (R) and ordered (P and V) patterns of TPU FMs were afforded using a rotating collector. Water contact angle and bacterial inhibition zone tests were performed to assess suitability of the system specifically for wound care. Stress–strain and in vitro drug release tests were performed to assess suitability of newly developed systems specifically for hybrid membranes (HMs). The highest tensile strength (32.1 ± 4.9 MPa) with elasticity (104.2 ± 6.0%) and the most sustained release rate indicate HMs (P) are potentially suitable materials for wound‐care applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47105.

Lecithin doped electrospun poly(lactic acid)-thermoplastic polyurethane fibers for hepatocyte viability improvement.

The development of hepatocyte cultures in vitro holds great significance in the study of bioartificial liver support systems. Electrospun fiber cultures have received widespread attention as an effective method to culture hepatocytes in vitro. Polylactic acid (PLA) -a synthetic polymer with high biocompatibility and biodegradability- is widely used to fabricate electrospun fibers in the biomedical field. However, the use of PLA is limited in cell cultures due to its brittleness, strong hydrophobicity, and lack of biologically active functional groups. In this study, thermoplastic polyurethane (TPU) and lecithin (Lec) were used to modify PLA by spiking them into the PLA electrospun solution in attempt to establish a suitable fiber scaffold for hepatocyte culture in bioreactors. TPU and lecithin incorporation into PLA increases the flexibility, hydrophilicity, and biologically active groups of the fibers which further promotes the growth, proliferation, and viability of hepatocytes. The morphology, wettability, and biocompatibility of the as-prepared PLA-TPU-Lec fibers were carefully characterized. The results showed that the PLA-TPU-Lec fibers possessed favorable morphology and hydrophilicity, as well as high biocompatibility ability. HepG2 cells on the PLA-TPU-Lec fibers and tissue culture plates (TCP) were exposed to hepatotoxins for 24 h and we found that HepG2 cells on the PLA-TPU-Lec fibers had higher viability than cells on TCP. The PLA-TPU-Lec fibers are therefore expected to be used in vitro for hepatocyte culture to improve cellular activity in artificial liver bioreactors.

Ultrastretchable Multilayered Fiber with a Hollow-Monolith Structure for High-Performance Strain Sensor.

As a crucial component of data terminal acquisition devices, flexible strain sensor has shown promising applications in numerous fields, such as healthcare, bodynet, the intelligent traffic system, and the robotic system. For stretchable strain sensor, it remains a huge challenge to realize a fine balance of wide detection range and high sensitivity. Here, an electrically conductive carbon nanotube/thermoplastic polyurethane fiber with a multilayered, hollow, and monolith structure, accompanying high stretchability (up to 476% strain) and low density (about 0.46 g/cm3) is fabricated through a facile coaxial wet-spun assembly strategy. The as-prepared fibers with a designed independent sensitive zone and flexible supporting zone possess an ultralow percolation threshold (0.17 wt %) and a tunable size and structure. This structure endows the fiber with a good integration of adequate flexibility, suitable strength, and high elongation at break for wearable electronics. The fiber, which is then assembled as a strain sensor, realizes the perfect combination of the wide sensing range (>350% strain), high sensitivity (gauge factor (GF) = 166.7 at 350% strain), and excellent working durability (>10 000 cycles). Our sensor could also detect small compressing deformations (0.35% N-1 at 0.025-50 N) by capturing the resistance change of the fiber with superior stability. The highly stretchable, light weight, and multilayered fiber with the designed hollow-monolith structure provides a new route for the preparation of high-performance wearable electronics.

Fabrication of Dielectric Elastomer Composites by Locking a Pre-Stretched Fibrous TPU Network in EVA.

Dielectric elastomer (DE) composites with high electrical breakdown strength and large voltage-induced deformation were developed by retaining pre-stretched thermoplastic polyurethane (TPU) fibers in ethylene vinyl acetate copolymer (EVA). The microstructure of the candidate E-TPU fiber membrane and EVA coated E-TPU (E-TPU/EVA) film were characterized by scanning electron microscopy (SEM). The quasi-static and dynamic mechanical property, and the electromechanical properties, including the dielectric constant, dielectric loss tangent, and electromechanical sensitivity, of the DE composites were evaluated. Initially, tensile tests demonstrated that the DE composites based on E-TPU/EVAs had a higher elongation at break of above 1000% but a low elastic modulus of approximately 1.7 MPa. Furthermore, dielectric spectroscopy showed that the E-TPU/EVA had a dielectric constant of 4.5 at the frequency of 1000 Hz, which was 1.2 times higher than that of pure EVA film. Finally, it was found from electromechanical test that the voltage induced strain of E-TPU/EVA rose to 6%, nearly 3 times higher than that of pure TPU film, indicating an excellent electromechanical property. The DE composites developed have demonstrated the potential to be good candidate materials in the fields of artificial intelligence, biomimicry and renewable energy.

Determination of benzotriazole UV absorbers in textile products made of polyurethane fibers by high-performance liquid chromatography with a photo diode array detector

In this study, we aimed to develop a simple method for the simultaneous analysis of seven benzotriazole (BZT) UV absorbers that are commonly used in urethane fiber products. Acetone/chloroform shaking extraction, tetrahydrofuran dissolution, and acetone/hexane soaking extraction methods were examined, and acetone/hexane soaking extraction was used for analysis because its operation was simply and the low-toxicity and small consumption volume of extraction solvents. All the BZT UV absorbers investigated in this study were subjected to qualitative/quantitative analysis by high-performance liquid-chromatography with a photodiode array detector. To avoid interference by co-elution substances, a wavelength of 340 nm was used for quantification. Good linearity of standard curve of every chemical was observed in the concentration range of 0.02–10 µg/mL. Sufficient reproducibility was achieved because their recoveries and its variance of coefficients were good values. Furthermore, limits of detection and limits of quantification obtained from recovery tests were 0.095 to 0.56 µg/g and 0.29 to 1.7 µg/g, respectively. Among the 39 polyurethane textile products analyzed, only 2-(2’-hydroxy-5’-methylphenyl)benzotriazole (UV-P), 2-(2’-hydroxy-3’-tert-butyl-5’-methylphenyl)-5-chlorobenzotriazole (UV-326), and 2-(2'-hydroxy-3',5'-di-α-cumylphenyl)-2H-benzotriazole (UV-234) were detected in 2 samples (1.2 to 1.7 µg/g), 8 samples (0.62 to 384 µg/g), and 16 samples (trace amounts to 935 µg/g), respectively.

Influence of different surface-coated carbon fibers on the properties of the poly(phenylene sulfide) composites

This paper aims to study the effect of different surface coatings of carbon fiber on the thermal, mechanical, and morphological properties of carbon fiber reinforced poly(phenylene sulfide) composites. To this end, unsized and different surface-coated carbon fibers were used. Prepared poly(phenylene sulfide)/carbon fiber composites were characterized by using Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, tensile test, dynamic mechanical analysis, and scanning electron microscopy. Tensile strength values of the surfaced-coated carbon fibers reinforced poly(phenylene sulfide) composites are higher than the unsized carbon fiber reinforced poly(phenylene sulfide) composite. The highest tensile strength and modulus values were observed for the polyurethane-coated carbon fiber reinforcement. Dynamic mechanical analysis studies indicated that polyurethane-coated carbon fiber reinforced composite exhibited higher storage modulus and better adhesion than the others. Differential scanning calorimetry results show that melting and glass transition temperature of the composites did not change significantly. Scanning electron microscopic studies showed that polyurethane and epoxy-coated carbon fibers exhibited better adhesion with poly(phenylene sulfide).

High throughput engineering and use of multi-fiber composite matrices for controlled active release

A tri-compartment centrifugal electrospinning system (TCCES) was designed and used to fabricate multiple fiber membranes (from individual polyvinyl pyrrolidone (PVP), thermoplastic polyurethane (TPU) and poly-methyl methacrylate (PMMA) fibers). Controlled engineering of membrane composition presents opportunities to control mechanical and water contact angle characteristics. Furthermore, control on drug release rate is achieved based on active hosting fiber type contributing towards the overall membrane. The current system enables a high degree of alignment, production rate and variations to composition, indicating clear potential in biomedical fields requiring the use of encapsulated or embedded drug in membrane materials.

Human Skin-Like, Robust Waterproof, and Highly Breathable Fibrous Membranes with Short Perfluorobutyl Chains for Eco-Friendly Protective Textiles.

Flexible smart membranes with superior waterproofness and extreme breathability are highly desirable for wearable uses. However, present waterproof and breathable materials suffer from limited performance efficiency, alarming environmental risks, and complicated fabrication procedures. We report on eco-friendly fibrous membranes with human skin-like, robust waterproof, and highly breathable capabilities that can be prepared via a facile electrospinning strategy. A novel polyurethane elastomer (C4FPU) possessing double-terminal short perfluorobutyl (-C4F9) chain is synthesized for the first time and incorporated into the polyurethane (PU) fiber matrix, endowing the membrane with mighty and durable hydrophobicity. Additionally, the employment of AgNO3 greatly decreased the maximum pore size ( dmax), contributing to the dramatically enhanced waterproofness. The resulting PU/C4FPU/AgNO3 fibrous membranes exhibit comprehensive properties of exceptional hydrostatic pressure (102.8 kPa), excellent water vapor transmission rate (12.9 kg m-2 d-1), high mechanical property (9.8 MPa), and significant antibacterial efficacy against Escherichia coli and Staphylococcus aureus. The successful synthesis of these intriguing membranes may provide a promising candidate for the new generation of key building blocks of the upscale protective garments.

Study on thermodynamic properties of polyurethane fibers under small strain

In thiswork, dynamic thermodynamic analyzer (DMA) was used to determine the stress-temperature relationship of polyurethane fibers to research the thermodynamic properties under small strains. The results show that the stress of polyurethane fibers increases with the increase of temperature. The study of the energy conversion during the heating processof polyurethane fibers demonstrates that the entropy change decreases with the increase of the strain while the enthalpy change has the contrary tendency. The entropy change is the key reason for the stress of polyurethane fibers.

Electrospun polyurethane nanofibrous composite impregnated with metallic copper for wound-healing application

In this study, a wound dressing based on polyurethane (PU) blended with copper sulphate nanofibers was developed using an electrospinning technique. The prepared PU and PU nanocomposites showed smooth fibers without any bead defects. The prepared nanocomposites showed smaller fiber (663 ± 156.30nm) and pore (888 ± 70.93nm) diameter compared to the pristine PU (fiber diameter 1159 ± 147.48nm and pore diameter 1087 ± 62.51nm). The interaction of PU with copper sulphate was evident in the infrared spectrum through hydrogen-bond formation. Thermal analysis displayed enhanced weight residue at higher temperature suggesting interaction of PU with copper sulphate. The contact angle measurements revealed the hydrophilic nature of the prepared nanocomposites (71° ± 2.309°) compared with pure PU (100° ± 0.5774°). The addition of copper sulphate into the PU matrix increased the surface roughness, as revealed in the atomic force microscopy (AFM) analysis. Mechanical testing demonstrated the enhanced tensile strength behavior of the fabricated nanocomposites (18.58MPa) compared with the pristine PU (7.12MPa). The coagulation assays indicated the enhanced blood compatibility of the developed nanocomposites [activated partial thromboplastin time (APTT)-179 ± 3.606s and partial thromboplastin time (PT)-105 ± 2.646s] by showing a prolonged blood clotting time compared with the pristine PU (APTT-147.7 ± 3.512s and PT-84.67 ± 2.517s). Furthermore, the hemolysis and cytotoxicity studies suggested a less toxicity nature of prepared nanocomposites by displaying low hemolytic index and enhanced cell viability rates compared with the PU membrane. It was observed that the fabricated novel wound dressing possesses better physicochemical and enhanced blood compatibility properties, and may be utilized for wound-healing applications.

Application of thin polyurethane plastering thermal insulation system in building energy conservation

In this paper, through the study of the principle and method of the preparation of rigid foam polyurethane foam, the foaming process was optimized and the best formula was obtained. The effect of thin plastering on the thermal stability of the composites was analyzed, and the mechanism of the action of coupling agent and straw fiber was discussed. Physical adding method was used to introduce thin plaster for rigid polyurethane thermal insulation material. Synergistic insulation system is formed in polyurethane system to improve its thermal insulation performance. At the same time, the failure mechanism of the straw fiber polyurethane foam was also discussed. It is concluded that the compressive strength of the straw wall reinforced foam plastics is enhanced due to the addition of thin plastering, which improves the compressive strength of the thin plastering polyurethane foam.

Experimental study on flexible concrete by using polyurethane fiber

Experimental study on flexible concrete by using polyurethane fiber

Study on tensile properties constitutive model of polyurethane fibers with different isocyanate index

In this study, a two-element model consisting of a non-linear spring and a viscous dashpot was proposed to simulate tensile curve of polyurethane fibers. The results showed that the two-element model can simulate the tensile curve of the polyurethane fibers better with a simple and applicable feature compared to the existing three-element model and four-element model. The effects of isocyanate index (R) on the hydrogen bond (H-bond) and the micro-phase separation of polyurethane fibers were investigated by Fourier transform infrared spectroscopy and x-ray pyrometer, respectively. The degree of H-bond and micro-phase separation increased first and then decreased as the R value increased, and gain a maximum at the value of 1.76, which is in good agreement with parameters viscosity coefficient η and the initial modulus c in the model.

Polyurethane nanofiber strain sensors via in situ polymerization of polypyrrole and application to monitoring joint flexion

Strain sensors made of intrinsically conductive polymers (ICPs) and nanofibers were fabricated and tested for suitability for use in wearable technology. The sensors were fabricated and evaluated based on their surface appearances, and electrical, tensile, and chemical/thermal properties. Polypyrrole (PPy) was in situ polymerized onto polyurethane (PU) nanofiber substrates by exposing pyrrole monomers to ammonium persulfate as oxidant and 2,6-naphthalenedisulfonic acid disodium salt as doping agents in an aqueous bath. The PPy treated PU nanofibers were then coated with polydimethylsiloxane (PDMS). Both pyrrole concentrations and layer numbers were significantly related to change in electrical conductivity. Specimen treated with 0.1 M of PPy and having three layered structure showed the best electrical conductivity. Regarding tensile strength, the in situ polymerization process decreased tensile strength because the oxidant chemically degraded the PU fibers. Adding layers and PDMS treatment generally improved tensile properties while adding layers created fracture parts in the stress–strain curves. The treatment condition of 0.1 M of PPy, two layered, and PDMS treated specimen showed the best tensile properties as a strain sensor. The chemical property evaluation with Fourier transform infrared and x-ray photoelectron spectroscopy tests showed successful PPy polymerization and PDMS treatments. The functional groups and chemical bonds in polyol, urethane linkage, backbone ring structure in PPy, silicon-based functional groups in PDMS, and elemental content changes by treatment at each stage were characterized. The real-time data acquired from the dummy and five human subjects with repetition of motion at three different speeds of 0.16, 0.25 and 0.5 Hz generated similar trends and tendencies. The PU nanofiber sensors based on PPy and PDMS treatments in this study point to the possibility of developing textiles based wearable strain sensors developed using ICPs.

Model and prediction of stress relaxation of polyurethane fiber

In this study, the effect of small strain (less than 10%) on hydrogen bond (H-bond) and crystallinity of dry-spun polyurethane fiber was investigated with fourier transform infrared spectroscopy and x-ray diffractometer, respectively. The results showed that the H-bond of hard segments hardly broke and its degree of crystallinity scarcely varied below strain of 10%. The fiber stress relaxation behavior at 25 °C under small strain was researched using dynamic mechanical analyzer. The stress relaxation modulus constitutive equation was obtained by transforming the non-linear relationship between stress and time into the linear relationship between stress and strain. The stress relaxation modulus master curve at 25 °C was established in terms of short-term stress relaxation tests at elevated temperatures (35 °C, 45 °C, 65 °C and 75 °C) according to time-temperature superposition principle (TTS) to predict long-term behavior within 353 year.

Development of Nanofiber Reinforced Double Layered Cabin Air Filter Using Novel Upward Mass Production Electrospinning Set Up.

Recently, numerous researchers are interested in the development of new air filter because of air pollution caused by rapid industrialization and urbanization. The major concerns in developing air filters are: pressure drop and filtration efficiency which are considered significant. As the pressure drop increases, the energy consumption becomes high. In this study, we developed a novel air filter (polyurethane fiber mat) for nano size filtration using a mass production electrospinning, which is expected to enhance filtration efficiency and pressure drop effects. To determine the optimal electrospinning conditions for filter efficiency, various concentrations (8, 10, 12 wt/wt%) of thermoplastic polyurethane were prepared and employed. Scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FT-IR) were used for fiber characterization, and finally, efficiency test was conducted to evaluate the filter performance of developed nanofiber-based air filter. From this study, it could be concluded that optimization by adjusting the polymer concentration and electrospinning operating condition was the best efficient alternative method to fabricate nano-fibrous air filter system with improved filtration performance.

Novel shape-memory polyurethane fibers for textile applications

In this work, thermoresponsive shape-memory polyurethane (SMPU) fibers were produced by melt spinning from different SMPU pellets. Afterwards, the knitted fabric samples were prepared by the obtained fibers. Some of the SMPUs used were synthesized previously in our laboratory whereas a commercial one, named DIAPLEX MM4520, was also evaluated in order to carry out comparative studies. All the SMPUs were characterized by different techniques, such as thermogravimetric analysis, differential scanning calorimetry, dynamic mechanical analysis and tensile testing. Moreover, the shape-memory capabilities of the fabrics were measured by thermo-mechanical analysis. The obtained results show that the synthesized SMPUs could be attractive candidates for potential applications such as breathable fabrics or moisture-management textiles.

Polarized emission from CsPbBr3 nanowire embedded-electrospun PU fibers

Interest in all-inorganic halide perovskites has been increasing dramatically due to their high quantum yield, band gap tunability, and ease of fabrication in compositional and geometric diversity. In this study, we synthesized several hundreds of nanometer long and ∼4 nm thick CsPbBr3 nanowires (NWs). They were then integrated into electrospun polyurethane (PU) fibers to examine the polarization behavior of the composite fiber assembly. Aligned electrospun fibers containing CsPbBr3 NWs showed a remarkable increase in the degree of polarization from 0.17–0.30. This combination of NWs and PU fibers provides a promising composite material for various applications such as optoelectronic devices and solar cells.

Mechanical and thermal conductivity properties of hemp fiber reinforced polyurethane composites

The aim of the present work is to introduce natural hemp fiber as reinforcement in the preparation of partially biodegradable green composites. Composite of rigid polyurethane (PU) and hemp fiber (H.F) ​​were prepared at different loading rates in (H.F) ​​(5%, 10%, 15%, 20%, 25% and 30%). Water absorption, thermal conductivity, and mechanical properties of composite were investigated as a function of fiber content. The results show that, the thermal conductivity of composites increases linearly with density. The mechanical properties of composites with 15% wt fibers loading provided a 40% increase in strength. Measured properties showed that polyurethane- hemp fibers composite present good insulating properties compared to the traditional insulation materials (glass wool, mineral wool etc.). Therefore, (PU-HF) insulation may provide a promising solution for building insulation.

Thermomechanical and Shape Memory Performances of Thermo-sensitive Polyurethane Fibers

This study is the first step to investigate usability of shape memory polyurethane (SMPU) fibers for smart garment applications. SMPU fibers were spun by wet spinning process and chemical/mechanical characterization was carried out. SMPU solutions were prepared with two different concentrations (20 % and 25 %) and three different coagulation bath concentrations (0 %, 1 % and 3 %) were used for determining optimum spinning parameters. For investigating influences of spinning process on crystal structure, mechanical, thermal and shape memory performances of fibers, X-ray diffraction (XRD), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), scanning electron microscopy (SEM) and mechanical tests were conducted. DSC and DMA analysis results show that shape memory polyurethane fibers have a glass transition temperature about 35-40 oC which is suitable for body temperature. Moreover, SMPU fibers showed good tensile performance with an average tenacity of 1.38 cN/dtex and elongation at break of 350 %. Thermo mechanical test results showed that, all shape memory fibers have good shape memory effect with recovery and fixity ratios up to 91 % and 71 % respectively.