Polyurethane Fibers Research Articles

Synthesis of polymeric electrospun nanofibers for application in waterproof-breathable fabrics

This study focuses waterproof-breathable fabric development by applying electrospun web of polyurethane (PU), PAN, and PES directly onto the substrate fabric. Advantages of textile fabrics of elastomeric nanofibrous membranes over gortex specimen are the mass production feasibility, high elastomeric properties, more body comfort parameters, and fabric production without holes and needle traces formation. In this work, we identified the PU nanofibrous membrane as the best and useful web for application in waterproof-breathable fabrics. Air permeability, water vapor transport rate, and resistance to water penetration average value for the prepared PU fibers web (sample of S1) were about 10 ml/s, 430 g/m2/24 h, 15 cm H2O. To improve waterproof-breathable characteristics of the membrane, the effects of electrospinning parameters on the fibers morphology and waterproof-breathable characteristics were investigated. PU concentration of 12% (w/w) and electrospinning voltage of 12 kV were identified as optimal conditions to reach uniform and fine PU nanofibers formation without any beads. Air permeability, water vapor transport rate, and resistance to water penetration average value for the final sample were recorded as about 2.5 ml/s, 840 g/m2/24 h, and 44 cm H2O, correspondingly. POLYM. ENG. SCI. 56:143–149, 2016. © 2015 Society of Plastics Engineers

Solid-state fermentation as a potential technique for esterase/lipase production by halophilic archaea.

Halophilic archaea are extremophiles, adapted to high-salt environments, showing a big biotechnological potential as enzyme, lipids and pigments producers. Four inert supports (perlite, vermiculite, polyurethane foam and glass fiber) were employed for solid-state fermentation (SSF) of the halophilic archaeon Natronococcus sp. TC6 to investigate biomass and esterase production. A very low esterase activity and high water activity were observed when perlite, vermiculite and polyurethane were used as supports. When glass fiber was employed, an important moisture loss was observed (8.6%). Moreover, moisture retention was improved by mixing polyurethane and glass fiber, resulting in maximal biomass and esterase production. Three halophilic archaea: Natronococcus sp. TC6, Halobacterium sp. NRC-1 and Haloarcula marismortui were cultured by submerged fermentation (SmF) and by SSF; an improvement of 1.3- to 6.2-fold was observed in the biomass and esterase production when SSF was used. Growth was not homogeneous in the mixture, but was predominant in the glass fiber thus was probably because the glass fiber provides a holder to the cells, while the polyurethane acts as an impregnation medium reservoir. To the best of our knowledge, this work is the first report on haloarchaea cultivation by SSF aiming biomass and esterase/lipase activity production.

Preparation and characterization of silver nanoparticle-reduced graphene oxide decorated electrospun polyurethane fiber composites with an improved electrical property

Abstract An approach for the preparation of silver nanoparticle-reduced graphene oxide/polyurethane composites (AgNP@RGO/PU) was proposed. An electrospinning process was utilized to fabricate a lightweight and flexible PU fiber mat. Graphene oxide (GO)/PU composites were prepared using a dip-coating method. Thus there happens a hydrogen bonding interactions between the GO sheets and PU fibers. A powerful reducing agent, hydriodic acid, was used to reduce GO/PU composites which transforms into RGO/PU composites. The composite exhibited low electrical resistance (3.5 × 10 2 Ω/sq) because of reduction reaction. Furthermore, AgNPs, which were modified with thiophenol, were deposited on the RGO/PU composite through π–π interactions between the aromatic functional groups on the AgNPs and the RGO by a dip-coating method. The obtained AgNP@RGO/PU composite exhibited a remarkably enhanced electrical property (

Taiwanin A incorporated polyurethane fiber sheets for prevention of postoperative cancer recurrence

In this study, we propose a single solution for prevention of postoperative complications and recurrence of highly metastatic gastrointestinal tract cancers. Here, we demonstrate preparation and characterization of Taiwanin A incorporated polyurethane fiber sheets with excellent mechanical properties and sustained drug release. Sheets with elastic modulus of 8 MPa and ultimate tensile strength of 30 MPa will provide support on surgical staple line preventing leakage at anastomosis. Slight burst release of the drug within 7 days (15%) and further sustained release will inhibit proliferation and migration of remaining cancer cells and maintain locoregional high drug concentration to prevent recurrence of the disease. High elasticity of the material will promote healing process without impeding natural peristalsis movement of gastrointestinal organs.

Comparative analysis of the effect of solvent on the structural and dynamic characteristics of film and nonwoven fiber materials prepared from polyurethane and styrene acrylonitrile

Structural and dynamic analysis, combining thermophysical measurements by differential scanning calorimetry and measurements of segmental mobility by the EPR microprobe technique, is performed for films and nonwoven fiber materials prepared from polyurethane (PU) and a styrene-acrylonitrile copolymer (SAN), as well as mixed compositions thereof. The effect of the tetrahydrofuran, ethyl acetate, and acetone solvents on the structure and molecular dynamics of films and matrices based on ultrathin PU and SAN fibers is examined. A weak effect of solvent on the molecular dynamics of chains in the PU film and nonwoven materials and a strong influence on the molecular mobility in SAN films and films of mixed compositions with a high SAN content are observed. For fibers, such influence is negligible. In PU and PU/SAN mixed formulations, mesomorphic structures are formed in both the film and nonwoven materials. The temperature dependence of the rotational correlation time τ of the probe exhibits a kink at temperatures close to the melting point of the mesomorphic structures in the PU/SAN mixtures. All the studied dependences for both the films and fibers feature a kink at PU/SAN = 50/50, which is associated with phase inversion in the compositions. The probe measurements show the impact of an oxidant (ozone) on the amorphous phase in these polymers. Measuring the rotational dynamics of the probe before and after exposure to ozone of the film and ultrafine fiber materials showed that, for both the PU films and fibers, ozonation produces practically no effect on the molecular dynamics, while for PU/SAN compositions and pure SAN, τ changes significantly.

Highly conductive and ultrastretchable electric circuits from covered yarns and silver nanowires.

Stretchable electronics, as a promising research frontier, has achieved progress in a variety of sophisticated applications. The realization of stretchable electronics frequently involves the demand for a stretchable conductor as an electrical circuit. However, it still remains a challenge to fabricate high-performance (working strain exceeding 200%) stretchable conductors. Here, we present for the first time a facile, cost-effective, and scalable method for manufacturing ultrastretchable composite fibers with a "twining spring" configuration: cotton fibers twining spirally around a polyurethane fiber. The composite fiber possesses a high conductivity up to 4018 S/cm, which remains as high as 688 S/cm at 500% tensile strain. In addition, the conductivity of the composite fiber (initial conductivity of 4018 S/cm) remains perfectly stable after 1000 bending events and levels off at 183 S/cm after 1000 cyclic stretching events of 200% strain. Stretchable LED arrays are integrated efficiently utilizing the composite fibers as a stretchable electric wiring system, demonstrating the potential applications in large-area stretchable electronics. The biocompatibility of the composite fiber is verified, opening up its prospects in the field of implantable devices. Our fabrication strategy is also versatile for the preparation of other specially functionalized composite fibers with superb stretchability.

Simulation of polyimide fibers with trilobal cross section produced by dry-spinning technology

As one type of high performance fibers, polyimide fibers can be prepared from polyamic acid (PAA) solution by dry-spinning technology. The transformation from the precursor of polyamic acid to polyimides via thermal cyclization reaction in the dry-spinning process is a main distinguishing feature, which is very different from other fibers produced by dry-spinning such as cellulose acetate fiber and polyurethane fiber. In this report, the dry-spinning formation of polyimide fibers with trilobal cross section from PAA solution in N,N-dimethylacetamide is simulated via a one-dimensional model based on a viscoelastic constitutive equation, combined with profile degree equation of cross section and imidization kinetics equation. The glass transition temperature, imidization degree and profile degree of the filament along the spinline are predicted by the model, as well as relative parameters such as solvent mass fraction and temperature. As a simulated result, solidification of polyimide fibers take place about 150 cm from the spinneret which is farther than for cellulose acetate fiber (70 cm). Moreover, the final profile degree of fiber is affected by many spinning parameters, such as spinning temperature, surface tension, spinning solution concentration, major, and minor axis length of the spinneret hole. POLYM. ENG. SCI., 55:2148–2155, 2015. © 2015 Society of Plastics Engineers

Biocompatible fibers from thermoplastic polyurethane reinforced with polylactic acid microfibers

Fiber-reinforced composites were prepared by extrusion of biphasic thermoplastic polyurethane/polylactic acid blends and the morphology was studied by electron microscopy. Reinforcing effect of in-situ formed PLA microfibers on polyurethane matrix was found. Polylactic acid (PLA) content was varied from 10 to 40wt% resulting in reinforced polyurethane matrices with fibrils of 200–800nm. Highly amorphous PLA fibrils crystallized when heated above glass transition, resulting in storage modulus increase as observed by dynamic mechanical analysis. Polyurethane (TPU) fibers reinforced with PLA microfibers had improved tensile strength and retained relatively high elongation, but elastic recovery decreased and hysteresis increased relative to the neat TPU. Orientation of fibers induced by cold drawing increased tensile strength and elastic modulus.

Spider-silk-like shape memory polymer fiber for vibration damping

In this study, the static and dynamic properties of shape memory polyurethane (SMPU) fiber are reported and compared to those of spider dragline silk. Although the polymeric fiber has a lower strength compared to spider dragline silks (0.2–0.3 GPa versus 1.1 GPa), it possesses much higher toughness (276–289 MJ m−3 versus 160 MJ m−3), due to its excellent extensibility. The dynamic mechanical tests reveal that SMPU fiber has a high damping capacity (tan δ = 0.10–0.35) which is comparable to or even higher than that of spider silks (tan δ = 0.15). In addition, we found that, different programming methods change the shape memory and damping properties of the fiber in different ways and cold-drawing programming is more advocated in structural applications. These results suggest that the SMPU fiber has similar vibration damping and mechanical properties as spider silk, and may find applications in lightweight engineering structures.

Investigation into stress recovery behavior of shape memory polyurethane fiber

ABSTRACTIn this work, the stress recovery behavior of shape memory polyurethane (SMPU) fiber was investigated. The as‐spun SMPU fibers were subjected to various programing‐recovery conditions. It was observed that recovering at 100 °C generated higher recovery stress than recovering at 150 °C. It was also found that, while hot‐drawn programed fiber has higher recovery stress than cold‐drawn programed fiber if recovered at 100 °C, cold‐drawn programed fiber has higher stabilized recovery stress than hot‐drawn programed counterpart when recovered at 150 °C. A morphological model was proposed based on the results from differential scanning calorimetry, Fourier transform infrared spectrometry, and X‐ray diffraction to understand the physics behind the different stress recovery behaviors. It is found that SMPU experiences different phase transitions and phase separations under different programing and stress recovery conditions. It is concluded that the two sequential phase separations taking place at 100 and 150 °C are primarily responsible for the differences in the stress recovery behavior. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014, 52, 1429–1440

Effect of the blocked ratio on properties of natural fiber–waterborne blocked polyurethane composites

In this paper, natural fiber/waterborne polyurethane composites were prepared from the imidazole blocked waterborne polyurethane and eucalyptus fiber mats. The related properties of blocked waterborne polyurethane and natural fiber/polyurethane composites were, respectively, measured by differential scanning calorimetry, dynamic mechanical analysis, dynamic contact angle, water absorption, and scanning electron microscope. The results showed that blocked waterborne polyurethane readily improved storage modulus ( G') and dynamic loss (tanδ) of the composites. The blocked ratio determined the density of the cross-linking structure in natural fiber/polyurethane composite and significantly affected natural fiber/polyurethane composite’s properties. With the increase of the blocked ratio, dynamic mechanical properties showed up a maximum value and the water absorption ratio reached a minimum value. The deblocking reaction of blocked waterborne polyurethane took place between 107.5℃ and 124.5℃. Due to these results, blocked waterborne polyurethane used as a matrix improved the dynamic mechanical properties of natural fiber/polyurethane composite.

Preparation and characterization of bioactive composites and fibers for dental applications

ObjectivesThe present study was carried out to create composites and fibers using polyurethane (PU) with hydroxyapatite (HA) that could be used for dental applications. MethodsComposites with varying HA concentration were prepared by solution casting technique. Similarly, PU–HA fibers with varying PU hard and soft segments and fixed HA concentration were also prepared. Various characterization techniques, such as, X-ray diffractometry, differential scanning calorimetry, scanning electron microscopy and Fourier transform infrared spectroscopy in conjunction with photo-acoustic sampling cell were employed to study the composites and fibers for changes in their physicochemical properties before and after immersion in artificial saliva at 37°C for up to 5 days. ResultsThe results indicated formation of amorphous apatite layers with maximum amorphicity in composites containing highest amount of HA with 5 days of immersion in artificial saliva. Similarly, fibers with more PU hard segment resulted in better transformation of crystalline HA to its amorphous state with increasing immersion time thus confirming the bioactive nature of the HA–PU fibers. SignificanceConcentrations of HA and PU hard segment along with the duration of immersion in artificial saliva are two major factors involved in the modification of solid-state properties of HA. The amorphous apatite layer on the surface is known to have tendency to bind with living tissues and hence the use of optimum amount of HA and PU hard segment in composites and fibers, respectively could help in the development of novel dental filling material.

Stem cell responses to plasma surface modified electrospun polyurethane scaffolds

The topographical effects from functional materials on stem cell behavior are currently of interest in tissue engineering and regenerative medicine. Here we investigate the influence of argon, oxygen, and hydrogen plasma surface modification of electrospun polyurethane fibers on human embryonic stem cell (hESC) and rat postnatal neural stem cell (NSC) responses. The plasma gases were found to induce three combinations of fiber surface functionalities and roughness textures. On randomly oriented fibers, plasma treatments lead to substantially increased hESC attachment and proliferation as compared to native fibers. Argon plasma was found to induce the most optimal combination of surface functionality and roughness for cell expansion. Contact guided migration of cells and alignment of cell processes were observed on aligned fibers. Neuronal differentiation around 5% was found for all samples and was not significantly affected by the induced variations of surface functional group distribution or individual fiber topography. From the Clinical EditorIn this study the influence of argon, oxygen, and hydrogen plasma surface modification of electrospun polyurethane fibers on human embryonic stem cell and rat postnatal neural stem cell (NSC) responses is studied with the goal of clarifying the potential effects of functional materials on stem cell behavior, a topic of substantial interest in tissue engineering and regenerative medicine.

Preparation of Modified Polyurethane Fiber and Study of its Lead Ions Adsorption

Modified polyurethane fiber was prepared by wet spinning method, Different amount of chitosan powder that dissolving in polyurethane solution to get spinning solution were examined. This materials presents excellent adsorption capacity on Pb2+. the absorption type on Pb2+ of this modified fibers was monomolecular. The modified fibers get the maximum adsorption 25.53mg/g when the quality ratio of chitosan and polyurethane was 1:1 under the condition of 30°C and pH 6.

Dyeing properties of mixture of ultrafine nylon and polyurethane with different types of dye

The dyeing and color fastness properties of levelling type acid dye, milling type acid dye, metal complex dye and reactive dye on ultrafine nylon, polyurethane fiber/film and their mixtures were investigated. Ultrafine nylon was dyed well with four types of dye at pH 3-6, but levelling type acid dye showed low washing fastness. Amine-rich polyurethane fiber exhibited enhanced dyeability due to amino groups which acted as dyeing sites, compared to regular polyurethane fiber. In simultaneous dyeing with milling type acid dye and metal complex dye, amine-rich polyurethane fiber absorbed more dye molecules than ultrafine nylon, the color difference between two fibers were apparent. Polyurethane-impregnated ultrafine nylon was also prepared and its build-up properties were determined. It was found that polyurethane whose soft segment was composed of polytetramethylene glycol (PTMG) and polypropylene glycol (PPG) showed improved dyeing property and subsequently high color strength.

Preparation of ultrafine polyurethane fiber web by laser-electrospinning combined with air blowing

Thermoplastic polyurethane fiber webs were prepared using a laser-heated electrospinning process combined with air blowing. The effect of spinning conditions such as air flow rate and air temperature on fiber diameter and molecular weight was investigated. Although the average fiber diameter decreased with increased air flow rate at each air temperature, the diameter increased when the air flow rate was >15 NL min−1. In addition, the fiber was comparatively thicker with an increase in the air temperature. The variation in the fiber diameter tends to increase with the air flow rate, and a reduction in the molecular weight of the fiber by thermal degradation was suppressed. The thinnest and most uniform fiber with a diameter of 0.9 µm and a diameter coefficient variation of 15% was obtained at an air temperature of 25°C under an air flow rate of 15 NL min−1. This fiber also had a minimum of decreased molecular weight. POLYM. ENG. SCI., 54:2605–2609, 2014. © 2013 Society of Plastics Engineers

Study on the bagging behavior of knitted fabrics by shape memory polyurethane fiber

The shape memory polyurethane (SMPU) fabrics were knitted with different SMPU fiber contents for the investigation of its bagging behaviour in this paper. The bagging deformation and recovery of these SMPU-knitted fabrics were determined at different temperatures to evaluate its temperature sensitivity. Our experimental results show that the bagging behavior of the SMPU-knitted fabrics is highly correlated with the amount of SMPU fibers knitted inside the SMPU fabrics. The switching temperature of the SMPU-knitted fabrics is found to be above the phase transfer temperature of SMPU. A comparison between Lycra and SMPU-knitted fabrics is also conducted to validate the shape memory bagging behavior of SMPU-knitted fabrics.

Novel elastomeric polyurethane fibers modified with polypropylene microfibers

Extrusion of immiscible polymer biphasic blends to form in situ microfibers of the minor component in the matrix of the major component is an elegant way to create composites with new properties. The process was used to obtain thermoplastic polyurethane elastomers modified with polypropylene microfibers. The effect of phase interaction on blend morphology and properties was studied by running a series of blends with and without a maleated polypropylene compatibilizer. Six different blends were prepared: three with compatibilizer and three without the compatibilizer. All blends contained polypropylene as a minor component (80/20; 90/10 and 95/5). Extrusion spinning of polyurethane/polypropylene blends with and without compatibilizer resulted in polyurethane fibers modified with highly-oriented polypropylene microfibrils at all component ratios. Increasing polypropylene concentration in the thermoplastic polyurethane matrix increased hardness and modulus, but did not affect tensile strength and lowered elastic recovery.

Thermal and mechanical properties of bio-based PCMs encapsulated with nanofibrous structure

An environmentally friendly phase change material (PCM) was successfully prepared by encapsulating natural soy wax into polyurethane (PU) nanofibers using coaxial electrospinning technique. The morphology and the structure of the wax/PU composites were characterized. Thermal behaviors as well as mechanical properties of the composites were also investigated. The results indicated that coaxial electrospinning produced uniform fiber morphology with a core–shell structure and a homogeneous wax distribution throughout the core of the fibers. The soy wax was successfully encapsulated into PU fibers without being miscible with PU fibers. Thermal analysis results show that the enthalpy increases as the wax content increases. The fibrous structures exhibited balanced thermal storage and released properties for thermo-regulating function. The thermal properties were unaltered after 100 heating–cooling cycles, demonstrating that the composite fibers had good thermal stability and reliability. Tensile tests also indicate that the presence of wax enhanced the modulus and lowered the tensile strain.

Conductive Polypyrrole/Polyurethane Composite Fibers for Chloroform Gas Detection

Flexible conductive fibers were fabricated by in-situ chemical polymerization of pyrrole monomers on the surface of polyurethane (PU) fibers. Compact polypyrrole (PPy) surface layer were observed, and moreover, high structural stability of the composite fibers can be obtained due to interpenetrating interface formation and strong interaction between PPy layers and PU matrix. More importantly, the composite fibers exhibited high sensitivity with relative fast response and recovery time, and good reproducibility for chloroform vapor detection.