Properties Of Polyurethane Research Articles

Electrical properties of bio-based polyurethanes derived from oleic acid

Electrical properties of bio-based polyurethanes derived from oleic acid

Effect of chain extender content on tribological properties of polyurethane under water‐lubrication

AbstractPolyurethane has been extensively studied as a multifunctional material for water‐lubricated bearing materials. As one of the polyurethane elastomeric synthetic material, the content of 4,4′‐methylene bis(2‐chloroaniline) (MOCA) directly affects the intermolecular structure and thus the properties of the material. Five samples with different MOCA contents were prepared by casting molding and tested. The results showed that the optimal comprehensive performance was obtained when the ratio of the amino group to the hydrocyanic acid group was 0.95, with tensile, compressive, and bending strengths of 50.1, 91.8, and 12.6 MPa, respectively. Compared with other samples, the surface of the sample was smooth, which was conducive to the formation of the water film. The bearing capacity and lubrication condition are improved, and the best tribological performance was shown. This research for the application of polyurethane elastomer on the water‐lubricated bearing provides a theoretical basis.

Correction to: Improving the mechanical, thermal and electrical properties of polyurethane- graphene oxide nanocomposites synthesized by in-situ polymerization of ester-based polyol with hexamethylene diisocyanate

Correction to: Improving the mechanical, thermal and electrical properties of polyurethane- graphene oxide nanocomposites synthesized by in-situ polymerization of ester-based polyol with hexamethylene diisocyanate

UV and UV+ Water Effects on Mechanical, Thermal and Morphological Properties of Thermoplastic Polyurethane Based Composites

The degradation times of composite materials containing petroleum-based polymer matrix are quite long in nature and it causes environmental pollution. Researchers focus on producing alternative composite materials with organic and/or inorganic fillers to reduce degradation times in nature. In addition, the mechanical and chemical properties of polymer matrix composites are affected by heat, light, moisture and surface compatibility between matrix and filler. In the light of this information, many researchers examine the mechanical, thermal, morphological and similar properties of organic and/or inorganic filler composites by using artificial aging processes using one or more of the water, UV and temperature parameters. In this study, bentonite with surface modification by epoxysilane agent, and bentonite without any surface modification will be added to the thermoplastic polyurethane (TPU) polymer matrix, which has two different segments, and will be mixed in a twin screw extruder and it will then be shaped by the injection molding process. Artificial aging processes of the obtained composites will be done under UV and UV+water for 2 and 4 weeks, respectively. The reason for choosing UV and UV+water processes is that UV and water processes have not been applied together at the same time and there is not much knowledge in the literature on this subject. Mechanical, thermal and morphological properties of composites were investigated.

Tuning the properties of breathable polyurethanes through chemical crosslinking

AbstractThe present work aims at improving the properties of waterproof breathable polyurethane membranes by introducing chemical crosslinks. A series of crosslinked polyurethanes were prepared by chain extension of prepolymer containing varying amounts of a triisocyanate‐based crosslinker (0–15% wt/wt). Thin polyurethane films (~40 μm) were prepared by a solution casting technique and the effect of introducing the crosslinker on thermal, mechanical characteristics was established. Crosslinking led to an increase in glass transition temperature. All crosslinked polyurethanes exhibited a sub‐ambient Tg. Both tensile and tear strengths were found to improve with crosslinking. Crosslinking (15% wt/wt) led to an increase in waterproofness from 112 ± 11 mbar to 574 ± 23 mbar, while the breathability reduced from 1246 ± 52 g/m2/day to 678 ± 32 g/m2/day. Polyurethane membranes containing 10% crosslinker exhibited an optimal balance of waterproofness and breathability, where the film was found to possess a water vapor transmission rate (WVTR) of 834 ± 37 g/m2/day with a hydrostatic pressure of 490 ± 18 mbar. This was subsequently coated on a cotton–polyester fabric to fabricate a breathable textile which was found to exhibit a WVTR of 663 ± 18 g/m2/day and a hydrostatic pressure of >3 bar, which was suitable for practical applications.

Synthesis and Characterization of Cellulose Based Injectable Polyurethane Gels

This article describes the synthesis and characterization of cellulose-based injectable polyurethane gels for tissue engineering applications. The gels were prepared by combining a cellulose derivative with a polyurethane precursor and crosslinking agent to form a stable gel under physiological conditions. The resulting gels were evaluated for swelling behavior.
 The addition of cellulose to polyurethane is a promising approach to improve the properties of polyurethane. Cellulose is an abundant, environmentally friendly and inexpensive polysaccharide polymer widely used in hydrogels, pharmaceuticals and agriculture. The obtained cellulose-based polyurethane composites were characterized in detail using various techniques such as Fourier transform infrared spectroscopy (FTIR), Thermogravimetric Analyzer (TGA), Differential Scanning Calorimeter (DSC), Differential Thermal Analysis (DTA), swelling test measurements and optical microscopy. The results showed that the obtained composites are suitable for the production of injectable insulating materials. The paper also briefly discusses the various uses of polyurethanes in different fields, including furniture manufacturing, medical devices such as hospital beds, catheters, injection-coated devices, wound dressings and surgical dressings, as well as marine, air and land vehicles. In conclusion, this paper provides valuable insights into the development of cellulose-based injectable polyurethane gels for tissue engineering applications and highlights the potential of cellulose as an additive to enhance the properties of polyurethane. The results of this study may contribute to the development of new and improved biomaterials for tissue engineering applications.

Preparation and Properties of Polyurethane with Self-Healing Function by Solvent-Free Method

Preparation and Properties of Polyurethane with Self-Healing Function by Solvent-Free Method

Synthesis and characterization of antibacterial self-healable biopolyurethanes with eugenol-based bio-polyol

In this study, antibacterial self-healable polyurethanes (EBPUs series) were prepared using eugenol-based bio-polyol (EBP), which was synthesized by thiol–ene reaction between eugenol and 1,2-ethanedithiol. The effects of EBP content on the mechanical, self-healing, and antibacterial properties of polyurethanes were investigated. When EBP was added into the EBPUs series as a polyol, the tensile strength, elongation at break, and self-healing efficiency values increased to 21.78 MPa, 1462.27%, and 77.85 %, respectively. EBPU−10 shows self-healing efficiency, where its first and second self-healing efficiency reached 76.6 % and 66.1 %, respectively. For antibacterial properties, the EBPUs series show promising antibacterial activity. EBPU−10 inhibited Staphylococcus aureus growth by 99.3 %, and Bacillus cereus growth by 95.7 %, and it inhibited Escherichia coli growth by 82.3 % at 6 h, compared to EBPU−01. Biofilm mass on foams was reduced by EBPU-10, and the morphology of biofilm bacteria was altered, such as their size being reduced, distorted, shrunken, and ruptured. In conclusion, it can be used for various applications, such as packaging, antimicrobial wound dressing, catheter, tissue adhesive, and surgical implant.

Artificial Neural Network model to predict the dynamic properties of sand-polyurethane composite materials for GSI applications

This study shows the modelling of the dynamic properties of sand-polyurethane composite materials through the Artificial Neural Network method (ANN). Such properties are relevant to assess the effectiveness of polyurethane injected into the foundation soil as Geotechnical Seismic Isolation (GSI) system. Three FeedForward Neural Network (FFN) models are developed for the prediction of the shear modulus decay, the normalised shear modulus decay and the damping ratio curve. Four inputs are considered, namely the dynamic properties of pure sand and pure polyurethane, the volumetric percentage of polyurethane and the isotropic confining stress. Each model is trained and tested on a database including previous experimental results of Resonant Column (RC) tests performed on layered sand-polyurethane specimens, with polyurethane volumetric percentages varying from 10% to 30%. In all cases, the network architecture is found to be optimal with a single hidden layer and the number of hidden neurons from 4 to 6 according to the complexity of the data to be fitted. By comparing the predicted properties with the experimental results, a good prediction quality of the models is shown both in terms of the coefficient of correlation R2 and the Mean Squared Error MSE. A relative importance analysis finally reveals that polyurethane mainly affects the properties of the composite materials with its volumetric percentage, rather than its dynamic properties especially in terms of shear modulus.

Thermal performance of thermoplastic polyurethane composites with microencapsulated piperazine pyrophosphate

This study synthesized and investigated the efficacy of a novel flame retardant, melamine formaldehyde microencapsulated piperazine pyrophosphate (MFPAPP), in improving the thermal and flame-retardant properties of thermoplastic polyurethane (TPU). When TPU was incorporated with 30wt% MFPAPP, the limiting oxygen index (LOI) value of the TPU/MFPAPP composite increased to 38.8%, achieving a V-0 rating. The thermogravimetric test (TG) results confirmed that MFPAPP significantly enhanced the thermal stability of the TPU/MFPAPP composite, as indicated by the increased char residue at 800°C, which was up to 22.4wt%. Compared with the pure TPU samples, the peak heat release rate (PHRR) and total heat release (THR) of TPU/MFPAPP30 decreased by 53% and 45%, respectively. TPU/MFPAPP10 maintained a V-0 rating after the water immersion test, whereas TPU/PAPP degraded to a V-2 rating. Scanning electron microscopy (SEM), Raman spectra, and X-ray photoelectron spectroscopy analyses revealed that MFPAPP promoted the formation of heat-resistant and dense expanded carbon layers. In summary, MFPAPP demonstrated remarkable flame retardancy and thermal stability, making it an ideal candidate for enhancing the fire safety of TPU materials.

Strength and durability that last—Mechanical properties of polyurea and polyurethane coated composites

AbstractMaterials scientists are interested in the development of impact‐resistant materials for military and commercial products. Polyurea and polyurethane are utilized for impact absorption in numerous industries, however, hybrid polymers and their features are rarely explored. Due to their distinct chemical structures and cure kinetics, polyurea‐polyurethane hybrid materials are still in their infancy. The versatility of these materials drives the research to address this challenge. Small‐scale composite companies generally use spray guns to apply chemicals, raising costs. The current study focused on the development of coated composites for impact applications. Polyurea, polyurethane, and their hybrid were used as a coating material on the glass/epoxy composites. The flexural, impact (Charpy and Izod), and thermomechanical properties of these coated composites were investigated. It was observed that coating thickness enhanced impact properties of composite materials. The loss and storage modulus decreased with an increase in temperature for polyurea and polyurethane coated composites. The thermo‐mechanical analysis of hybrid coated composite showed the behavior to be dominantly similar to the polyurethane‐coated composite materials. The flexural strength of glass/epoxy composites increases with the coating, while increasing number of coating layers counters this effect.

A phosphorus- and nitrogen-containing aromatic Schiff base derivative in waterborne polyurethane backbone for excellent flame retardant, UV-shielding and mechanical properties

Waterborne polyurethane (WPU) is widely used in the fields of coatings, adhesives and treatment agents. However, the WPU is highly flammable and has a high demand for UV-shielding property in practical application. To date, it remains a challenge to effectively improve the flame retardant and UV-shielding properties without compromising the inherent mechanical property. Here, we report a novel flame retardant WPU (FRWPU) with 9, 10-dihydro-9-oxo-10-phosphophenanthrene-10 oxide (DOPO)-based aromatic Schiff base derivative containing phenolic hydroxyl (DOPO-HAMB) in the backbone. Compared to the pristine WPU, the FRWPU reaches the limiting oxygen index (LOI) value of 27.9 %, and achieves a V-0 rating in the UL-94 test with only 3 % of DOPO-HAMB. Meanwhile, in the cone calorimetry test, the peak heat release rate (pHRR) and total heat release (THR) of FRWPU are reduced by 37.7 and 29.3 %, respectively. In addition, the FRWPU can suppress melt dripping and smoke release during combustion effectively. These enhancements are attributed to the cooperation between DOPO and aromatic Schiff base derivatives with both gas-phase and condensed-phase flame retardant mechanisms. More interestingly, the FRWPU exhibits excellent UV shielding property while maintaining the inherent mechanical property of polyurethane, which provides a useful reference for the design and fabrication of flame retardant waterborne polyurethane.

Morphological Electrical and Hardness Characterization of Carbon Nanotube-Reinforced Thermoplastic Polyurethane (TPU) Nanocomposite Plates.

The impacts on the morphological, electrical and hardness properties of thermoplastic polyurethane (TPU) plates using multi-walled carbon nanotubes (MWCNTs) as reinforcing fillers have been investigated, using MWCNT loadings between 1 and 7 wt%. Plates of the TPU/MWCNT nanocomposites were fabricated by compression molding from extruded pellets. An X-ray diffraction analysis showed that the incorporation of MWCNTs into the TPU polymer matrix increases the ordered range of the soft and hard segments. SEM images revealed that the fabrication route used here helped to obtain TPU/MWCNT nanocomposites with a uniform dispersion of the nanotubes inside the TPU matrix and promoted the creation of a conductive network that favors the electronic conduction of the composite. The potential of the impedance spectroscopy technique has been used to determine that the TPU/MWCNT plates exhibited two conduction mechanisms, percolation and tunneling conduction of electrons, and their conductivity values increase as the MWCNT loading increases. Finally, although the fabrication route induced a hardness reduction with respect to the pure TPU, the addition of MWCNT increased the Shore A hardness behavior of the TPU plates.

Improved anticorrosion, flame retardant and mechanical behaviors of multifunctional polyurethane nanocomposite coatings for industrial applications

The anticorrosion, flame retardant, and mechanical properties of polyurethane (PU) coatings have been enhanced by the inclusion of zirconium disulphide (ZrS2), 2-mercapto-5-(methoxy)-1,3,4-thiadiazole (MMTD), and graphene oxide (GO). The structural and morphological behaviours of the films for the different coating formulations were investigated using SEM/EDX (Scanning Electron Microscopy with Energy Dispersive X-Ray Spectroscopy), TEM (Transmission Electron Microscopy), TGA (Thermogravimetric Analysis), XPS (X-ray Photoelectron Spectroscopy), and XRD (X-ray Diffraction) analysis. With the inclusion of just 0.3% GO/MMTD-ZrS2, the dielectric constant of PU at 1 Hz was increased by 85 times. Additionally, when compared to plain PU, the PU-GO/MMTD-ZrS2 demonstrated increased flame retardancy with significant decreases in the peak heat release rate (pHRR) and total heat released (THR), or reductions of 65% and 52%, respectively. The addition of GO/MMTD-ZrS2 compound to the PU matrix improves the PU coating's anticorrosive, hydrophobic, flame retardancy, and mechanical performance. The hyper hydrophobic behavior is verified by its water contact angle (WCA), which is 168˚. Additionally, it was discovered that PU-GO/MMTD-ZrS2 had considerably higher coating resistance (20,997.1 kΩ.cm2) compared to the other coatings under investigation. PU-GO/MMTD-ZrS2 was found to have a microhardness of 1355 MPa and a binding strength of 17.9 MPa, respectively. This means that the PU-GO/MMTD-ZrS2 nanocomposite could be applied in industrial settings as a coating substance.

Hydrophobic, Mechanical, and Physical Properties of Polyurethane Nanocomposite: Synergistic Impact of Mg(OH)2 and SiO2.

Polyurethane (PU) is one of the most well-known polymer coatings because of its favorable characteristics, which include its low density, nontoxicity, nonflammability, longevity, adhesion, simple manufacture, flexibility, and hardness. However, PU does come with several major drawbacks, among which are poor mechanical properties as well as low thermal and chemical stability, particularly in the high-temperature mode, where becomes gets flammable and loses adhesion ability. The limitations have inspired researchers to develop a PU composite to improve the weaknesses by adding different reinforcements. Magnesium hydroxide, having the ability to be produced with exceptional properties such as flammability, has consistently attracted the interest of researchers. Additionally, silica nanoparticles with high strength and hardness are one of the excellent reinforcements of polymers these days. The hydrophobic, physical, and mechanical properties of pure polyurethane and the composite type (nano, micro, and hybrid) fabricated with the drop casting method were examined in this study. 3-Aminopropyl triethoxysilane was applied as a functionalized agent. To confirm that hydrophilic particles turned into hydrophobic, FTIR analysis was carried out. The impact of size, percentage, and kind of fillers on different properties of PU/Mg(OH)2-SiO2 was then investigated using different analyses including spectroscopy and mechanical and hydrophobicity tests. The resultant observations demonstrated that different surface topographies can be obtained from the presence of particles of different sizes and percentages on the hybrid composite's surface. Surface roughness allowed for exceptionally high water contact angles, which confirmed the hybrid polymer coatings' superhydrophobic properties. According to the particle size and content, the distribution of fillers in the matrix also improved the mechanical properties.

Multilayered nanocomposite coatings for enhanced anticorrosive, flame retardant, and mechanical properties in automobile and aerospace industries

AbstractThe anticorrosion, flame retardant, and mechanical properties of polyurethane (PU) coatings have been improved by the integration of nickel disulfide (NiS2), 2,5‐Bis(4‐aminophenyl)‐1,3,4‐oxadiazole (BAO), and graphene oxide (GO). The structural, morphological, dielectric, and hydrophobic behaviors of the films were characterized for the different formulations of coatings such as pure PU, PU‐NiS2, PU‐BAO/NiS2, PU‐GO/NiS2, and PU‐GO/BAO‐NiS2(nanocomposite) by means of scanning electron microscope/X‐ray energy dispersive spectroscopy, transmission electron microscope, thermogravimetric analysis, X‐ray photoelectron spectroscopy, X‐ray diffraction, and contact angle measurement. As a result, with the addition of only 0.3% GO/BAO‐NiS2, the dielectric constant of PU was increased by 81‐fold at 1 Hz. Additionally, the nanocomposite had significantly lower peak heat release rate and overall heat released values than pure PU, a difference of 57% and 51%, respectively, demonstrating its greater flame retardancy. The electrochemical techniques and mechanical testing confirmed that GO/BAO‐NiS2(0.3%) composite exhibit enhanced anticorrosive, hydrophobic, flame retardancy, and mechanical performance of the PU coating. The super hydrophobic behavior is confirmed by its water contact angle of 165°. Furthermore, the resistance of the nanocomposite was found to be much higher (16,985.6 kΩ.cm2) than that of the pure PU (145.4 kΩ.cm2) and the microhardness and tensile strength were increased sharply. Therefore, the nanocomposite could act as a potential coating material for industrial applications.

Dual Stimuli-Responsive Orthodontic Aligners: An In Vitro Study.

Aligner therapy for orthodontic tooth movement is gaining importance in orthodontics. The aim of this contribution is to introduce a thermo- and water-responsive shape memory polymer (SMP), which could lay the foundation for a new type of aligner therapy. The thermal, thermo-mechanical, and shape memory properties of thermoplastic polyurethane were studied by means of differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and various practical experiments. The glass transition temperature of the SMP relevant for later switching was determined to be 50 °C in the DSC, while the tan δ peak was detected at 60 °C in the DMA. A biological evaluation was carried out using mouse fibroblast cells, which showed that the SMP is not cytotoxic in vitro. On a digitally designed and additively manufactured dental model, four aligners were fabricated from an injection-molded foil using a thermoforming process. The aligners were then heated and placed on a second denture model which had a malocclusion. After cooling, the aligners were in a programmed shape. The movement of a loose, artificial tooth and thus the correction of the malocclusion could be realized by thermal triggering the shape memory effect, at which the aligner corrected a displacement with an arc length of approximately 3.5 mm. The developed maximum force was separately determined to be about 1 N. Moreover, shape recovery of another aligner was realized within 20 h in 37 °C water. In perspective, the present approach can help to reduce the number of orthodontic aligners in therapy and thus avoid excessive material waste.

Mechanical properties of foamed polyurethane solidified ballasted track

Foamed Polyurethane Solidified Ballasted Track (FPSBT), an innovative railway track, is formed by solidifying ballast bed with foamed polyurethane. Compared with the traditional Discrete Ballasted Track (DBT), FPSBT does not require regular maintenance such as tamping and cleaning. However, limited studies exist on the mechanical properties of FPSBT. In this study, Laboratory experiments are conducted on polyurethane samples to investigate the effects of polyurethane density on the mechanical properties of FPSBT. Furthermore, the performance of DBT and FPSBT with different polyurethane densities are compared, and the recommended polyurethane density is obtained. FPSBT exhibited negligible accumulation of deformation under cyclic loads, indicating excellent performance of FPSBT owing to the anti-deformation properties of polyurethane. Further, a track load vehicle test is conducted. FPSBT exhibited better load-transmitting ability than DBT. Finally, the construction and application of FPSBT in China are introduced. This study is expected to contribute to realizing a more extensive application of FPSBT.

Modification of ZSM‐5 zeolite nanoparticles by graphene oxide to improve anticorrosion properties of polyurethane coating

AbstractPolyurethane coatings are a good option for the protection of various structures due to their unique properties. In order to improve their barrier performance against corrosive species, various nanoparticles have been embedded into polymer coating. In this project, the ZSM‐5 zeolite nanoparticles are modified with graphene oxide. Field emission scanning electron microscopy and Fourier transform infrared spectroscopy are used for characterizing unmodified and GO‐modified ZSM‐5 zeolites. The effect of ZSM‐5 zeolite and ZSM‐5 zeolite modified with GO addition on the anticorrosion properties of polyurethane (PU) coating is evaluated by electrochemical impedance spectroscopy, Tafel polarization, and Pull‐off tests. Modification of ZSM‐5 zeolite with GO has greatly influenced the anticorrosion properties of zeolite nanoparticles in polyurethane coatings. Among various PU coatings, the PU/ZSM‐5‐GO coating on mild steel shows the best protective properties (highest Rct and lowest icorr) against active corrosive species.

Preparation and Properties of Hydrophobic Polyurethane Based on Silane Modification.

Waterborne coatings have obtained more and more attention from researchers with increasing concerns in environmental protection, and have the advantages of being green, environmentally friendly and safe. However, the introduction of hydrophilic groups leads to lower hydrophobicity and it is difficult to meet the requirements of complex application environments. Herein, we proposed an optimization approach of waterborne polyurethane (WPU) with vinyl tris(β-methoxyethoxy) silane (A172), and it was found that the surface roughness, mechanical properties, thermal stability and water resistance of WPU will be increased to a certain extent with the addition of A172. Moreover, the hydrophobicity of the coating film is best when the silicon content is 10% of the acrylic monomer mass and the water contact angle reaches 100°, which could exceed two-thirds of the research results in the last decade. Therefore, our study can provide some theoretical basis for the research of hydrophobic polyurethane coatings.