Pure Polyurethane Research Articles

In Situ Formation of MoS2 on the Surface of CF to Improve the Tribological Properties of PUE.

The roller is an important part of the belt conveyor used in coal transportation. Due to the harsh environment of coal mines, the rollers are in a state of high load and high friction for a long time, which causes wear failure and has a serious impact on the reliability and safety of the equipment. In order to prepare roller material with excellent bearing performance and friction performance, CF/PUE composites were prepared by pouring method with polyurethane as the matrix and carbon fiber as reinforcement. Due to the low surface activity of unmodified carbon fibers and poor bonding performance with the matrix, MoS2 was generated on the surface of carbon fiber by the in situ generation method in this paper. It was found that the mechanical properties of MoS2/CF/PUE composites were better when the CF content was 0.3 wt%. The Shore hardness reached 92.2 HA, which is 10% higher than pure polyurethane. The tensile strength was 38.44 MPa, which is 53% higher than pure polyurethane. The elongation at break was 850%, which is 16% higher than pure polyurethane. The maximum compressive stress was 2.32 MPa, which is 42% higher than pure polyurethane. The friction coefficient was much lower than that of pure PUE composites, the friction coefficient was 0.284, which is 59% lower than pure polyurethane.

Influence of microphase separation and crosslinking density on dynamic viscoelastic properties of nano‐Fe3O4 modified polyurethane

AbstractAlthough there have been some studies on the preparation and characteristics of nano‐Fe3O4‐filled polyurethane (PU) composites, research focusing on the quantitative influence of the degree of microphase separation (DPS) and the crosslinking density (CLD) on dynamic viscoelastic properties is rare. In this paper, PU composites are synthesized by incorporating nano‐Fe3O4 as fillers. The dynamic mechanical properties under alternating loads are investigated using dynamic mechanical analysis. The influences of the DPS and the CLD on the dynamic hysteresis loss are analyzed. The experimental results show that the DPS and CLD of PU nanocomposites increase and then decrease with the increase of nano‐Fe3O4 addition and reached a maximum at the addition amount of 1.0 wt%. The quantitative relationships between DPS, CLD and the dynamic hysteresis loss of PU nanocomposites at different filler ratios are obtained. With a 1.0 wt% nano‐Fe3O4 content, the strain energy density (SED) and hysteresis energy density (HED) are increased by 416% and 354%, respectively. The hysteretic loss H indexes of all composites are kept lower than that of pure PU. These characteristics make nano‐Fe3O4‐filled PU a promising material for reducing the rolling resistance and increasing the service life of fuel‐saving tire materials.

A tough and stretchable colorimetric sensor based on a curcumin-loaded polyurethane electrospun fiber mat for hazardous ammonia gas detection

In this study, a flexible colorimetric sensor is developed to detect harmful ammonia gases using curcumin, a natural pH indicator. By applying an electrospinning method, the flexibility of polyurethane (PU) and the colorimetric characteristics of curcumin were simultaneously expressed in each nanofiber constituting the mat sensor. The physical properties of the mat according to the loaded curcumin concentration were investigated. And, the gas detection behavior was confirmed by the color change response of the mat to ammonia gas. Through the above process, the optimal conditions for fabricating a flexible colorimetric gas sensor with excellent tensile strength and elastic strain were established. The sensor fabricated with the curcumin loading of 30 wt% demonstrated approximately 3.5 times higher tensile strength and strain at break than the pure PU fiber mat. In addition, the color of the mat sensor changed from orange to red in proportion to the concentration of ammonia gases. Finally, the newly developed curcumin-PU mat could effectively withstand repeated external physical stress and was suitable for warning of dangerous toxic gas situations through immediate visual detection, even when repeatedly exposed to harmful gas.

Polipropilen Lif Türü, İçeriği ve Uzunluğunun Sert Poliüretan Kompozitlerin Mekanik Performansına Etkisi

The purpose of this work is to improve mechanical properties of rigid polyurethane (RPU) composites used in traditional ceramic casting industry. Therefore, monofilament (mono) and fibermesh (fibril) polypropylene (PP) fibers with various lengths (3, 6, 12 and 18 mm) were incorporated to polymer matrix at different rates (0.5, 1.0, 1.5 and 2% by weight). Effects of fiber type and content on flexural strength, bending strength and compressive strength of composites were investigated. Surface morphology and thermal characteristics of composites were evaluated by SEM and TGA analysis, respectively. Bulk densities of specimens with and without PP fibers vary between 72,15-146 kg/m3. Compared to pure rigid polyurethane foam, bulk density of monofilament PP reinforced composites significantly increased and the highest density value (146,86 kg/m3) was reached in M6/2.0 sample. On the other hand, incorporation of fibrilmesh caused a decrease in bulk density. While the increase in percentage of mono PP increased flexural strength, the presence of fibril PP had a negative effect on strength. Compressive strength of all mono PP reinforced composites is higher than that of pure RPU, except for M6/0.5 sample. Besides, SEM analysis revealed that the presence of PP fibers generally reduced number of closed cells in composite structure. Experimental findings indicate that fiber type, content and length affect mechanical performance of RPU composites. In addition, it is possible to use mono PP fiber reinforced RPU composites as support apparatus in ceramic casting industry.

Effect of polyurethane material design on damping ability

AbstractPolyurethane (PU) materials attract the interest of researchers for use in damping and vibration isolation. However, an undesirable property of pure polyurethane is a narrow temperature range of mechanical energy absorption. This study presented several ways to design damping PU materials based on two initial polyurethanes with different prepolymer compositions. The difference between the glass transition temperatures of initial PUs was 30°C. One way of designing was to obtain PU material based on a mixture of the two different prepolymers. Another way was to fabricate two‐layer composites from layers of different initial PUs. Тwo‐layer PU composites were fabricated in such ways as by sequential formation layer by layer or by gluing individual films. Continuous materials with a good connection between the layers were formed. Fourier transform infrared spectroscopy, light microscopy, contact angle measurements, and tensile tests were used for PU materials characterization. Dynamic mechanical analysis was used to investigate the viscoelastic properties and evaluate damping ability. The temperature ranges of effective damping (tan δ ≥ 0.3) from −27°C to 17°C and from −5°C to 42°C were shown for initial PUs. One high loss factor maximum for mixed‐base polyurethane was observed, and the temperature range of effective damping was from −20°C to 32°C. All designed two‐layer composites were shown two loss factor maxima. Their effective damping occurred either in one temperature range (−25°C to 29°C) or in two (−24°C to −14°C and −7°C to 37°C), depending on the design of the composite. The advantage of polyurethane materials design ways such as mixed‐base and two‐layer composite is the ease of control of the temperature region of effective damping. Proposed polyurethane materials designs offer a new approach to developing high‐performed damping materials.

Interactions of hydrophilic birch wood (Betula pendulaRoth) extractives with adhesives for load-bearing timber structures

This study investigated how water-soluble extractives of silver birch (Betula pendulaRoth) wood interact with the most common adhesives used for producing engineered wood products (EWPs), i.e., melamine-urea-formaldehyde (MUF) and one-component polyurethanes (PUR). Therefore, the extractives were characterized via various chromatographic techniques and mass spectrometry. The effects of extractives on the curing kinetics were investigated using rheometry. The impact of extractives on the chemical and mechanical properties of the cured adhesives was investigated with FTIR spectrophotometry and tensile stress-strain measurements, respectively. Moreover, a comparative study on the shear strength of birch wood with and without extractives was performed.The organic fraction of the water extractives of birch mainly consisted of phenolic glycosides, carboxylic (fatty) acids, and saccharides. The extractives decelerated the curing process of MUF, as observed in a rheological small-angle oscillatory shear experiment using wood substrates as the lower plate. This was indicated by a reduced gel time from 5 to 3.8 h on pristine vs. extracted wood. When measuring MUF on extracted wood, this deceleration was also reached by adding ∼1% (W/W) of the isolated extractives into the MUF resin. Similar experiments with PUR showed a slight acceleration when dispersing extract into the adhesive, indicated by a reduction of vitrification time of −0.9 ± 0.3 h per percent of extractives added. However, measurements with pure PUR on pristine and extracted wood showed no significant difference in curing kinetics due to the extractives’ limited mobility and solubility in PUR. Both PUR and MUF cured adhesive films showed a reduced stiffness, elastic stress limit and tensile strength in uniaxial tensile stress-strain measurements of adhesive films upon increasing the amount of hydrophilic birch extractives concentration. Comparative standard tensile shear strength measurements on pristine and extracted wood indicate a 7–19% strength increase due to extraction when bonding with MUF, while the bond strength of PUR bond lines was less affected by the extraction procedure.

Addition of aceh bentonite in an effort to improve the heat resistance properties of polyurethane-based paint coatings

Polyurethane is a polymer compound whose main chain constituent is urethane group (-NHCOO-). Polyurethanes can be mixed with other polymers or other fillers in an effort to enhance and improve the properties of the single polymer. Metal coating materials are needed for metal materials that have properties resistant to heat thermal condition and corrosion that can damage the structure,. The priority and novelty of this research is to utilize the natural bentonite which is very potential in the local area to fill polyurethane-based coating paint in order to improve its properties. This research looked at the effect of mixing Polyurethane with Bentonite filler obtained from Nisam, North Aceh which has been modified with CTAB and AgNO3 surfactants. The sample formulation used is polyurethane and polyurethane with North Aceh Bentonite variations of 1.5, 2.5, and 3.5%. Characterization with the addition of Bentonite produces polymers that have good thermal stability capabilities. The addition of Bentonite filler into polyurethane polymer can affect the mechanical properties of the material. The Polyurethane/Bentonite composite sample has better thermal resistance, where in pure Polyurethane, the initial weight reduction of the pure Polyurethane sample is 50-150 ℃, the decomposition of pure Polyurethane is at 385 ℃. For Polyurethane/Bentonite 98.5:1.5% w/w nanocomposite, the initial weight reduction is 150-300 ℃, decomposition at 416 ℃. For Polyurethane/Bentonite 97.5:2.5 w/w, the initial weight reduction is 150-250 ℃ and decomposition at 430 ℃. Polyurethane/Bentonite 96.5:3.5 w/w initial weight reduction is also at 200-300 ℃ and decomposition at 458 ℃.

Investigation of anticorrosion, flame retardant and mechanical properties of polyurethane/GO nanocomposites coated AJ62 Mg alloy for aerospace/automobile components

The addition of cerium disulphide (CeS2), 3, 5-Diamino-1, 2, 4-triazole (DAT), and graphene oxide (GO) has improved the anticorrosion, flame retardant, and mechanical qualities of polyurethane (PU) coatings. By using SEM/EDX, TEM, TGA, XPS, and XRD, the structural, and morphological behaviors of the films were studied for the various composites. These composites are incorporated into the PU to produce pure PU, PU-CeS2, PU-DAT/ZrS2, PU-GO/CeS2, and PU-GO/DAT-CeS2 coating materials. It was shown that a weight ratio of 0.3 for GO/DAT-CeS2 in the PU matrix produced the best coating performance. Additionally, compared to plain PU, the PU-GO/DAT-CeS2 showed greater flame retardancy with substantial drops in the values of PHRR and THR, or 75 % and 66 % reductions, respectively. The anticorrosive, hydrophobic, flame retardancy, and mechanical performance of the PU coating are improved on the introduction of GO/DAT-CeS2 composite in PU matrix. As evidenced by its WCA of 159°, the hyper hydrophobic behavior is validated. In addition, the coating resistance of PU-GO/DAT-CeS2 was found to be significantly greater (21,991 kΩ.cm2) than those of the other investigated coatings. The adhesive strength, tensile strength and microhardness of PU-GO/DAT-CeS2 were observed to be 1370 MPa, 215 MPa and 20.1 MPa, respectively. In light of this, the PU-GO/DAT-CeS2 nanocomposite may be used as a coating material in industrial and aerospace applications.

Preparation, Characterization and Tribological Performance of Polyurethane (PU) Coatings Filled with Graphene Oxide (GO)

The polyurethane coatings containing different concentration of graphene oxide were prepared. Their physicochemical properties were characterized by XRD and SEM. The tribological behaviors were also investigated by ring-on-block tests. Results revealed that the TDI adsorb on the surface of GO through reaction with O-H. The COF were extremely sensitive to the GO concentration of PU coatings filled. The COF of pure PU coating was 0.185, whereas it is sharply decreased when 1.0 wt% GO was added. Smaller COF was obtained as the GO concentration increase and to minimize when GO concentration is 2.0 wt%. Friction reduced mechanism of GO was further investigated. Two reasons were responsible for this phenomenon. The one was that the GO itself possessed the capacity of anti-wear and friction reduction. Another one was the GO dispersed in the PU coatings could increase the strength of the coatings by the mean, which was similar to dispersion strengthening.

Fabrication of organic/inorganic hybrid waterborne polyurethane coating based on CeNPs @mTi3C2Tx composites for anti-corrosion applications

Ti3C2Tx has been studied as a nano-filler in anti-corrosion coatings, but its poor dispersion, interfacial interaction in coatings and poor long-term anti-corrosion performance limit its application. A series of organic/inorganic hybrid waterborne polyurethane anti-corrosion coatings were designed and prepared based on the barrier effect of MXene and the passivation mechanism of CeNPs, providing a green, environmentally friendly, and long-term efficient organic/inorganic hybrid anti-corrosion method. FT-IR, zeta potential, XPS and EDX analysis showed that the nano ceria was successfully loaded in mTi3C2Tx. SEM testing showed that the synthesized CeNPs @MXene filler had good dispersion and compatibility in polyurethane. According to the results, CeNPs, mTi3C2Tx, and CeNPs @mTi3C2Tx could enhance the anti-corrosion efficiency of waterborne polyurethane and prolong the anti-corrosion time. At the same time, WPU/CeNPs @ mTi3C2Tx exhibited an order of magnitude higher low-frequency impedance modulus than pure waterborne polyurethane and shown superior corrosion resistance over WPU/mCeNPs and WPU/mTi3C2Tx. The best anti-corrosion performance was achieved when the content of CeNPs @mTi3C2Tx was 1.5 wt%. The |Z|0.01Hz value was still close to 108 Ω·cm2 after 120 days of immersion.

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.

The applications of flower-shaped ZnO-UHMWPE fibers in photocatalysis and composites

Ultra-high molecular weight polyethylene (UHMWPE) fiber is considered as one of the high-performance fibers. However, the inert surface of UHMWPE fiber limits its application in many fields. In order to optimize the application of UHMWPE fibers in functional and composite fields, this work introduced a special surface structure of the UHMWPE fibers. The designed surface was formed by the flower-shaped ZnO (F-ZnO) crystals, which endowed the UHMWPE fibers with photocatalytic property. Moreover, F-ZnO on the UHMWPE fiber surface enhanced the roughness of the fiber, which improves the interfacial bonding strength of fiber-reinforced composites. The experimental results showed that the surface wettability of the F-ZnO-UHMWPE fibers was improved significantly. Moreover, F-ZnO-UHMWPE fibers were used as immobilized photocatalyst, and the degradation rate of rodamine B reached 53.3 %. F-ZnO-UHMWPE fiber also could be used in fiber-reinforced composites fields. Compared with the pure rigid polyurethane (RPU) and UHMWPE fibers/RPU composites, the tensile strengths of F-ZnO-UHMWPE fibers/RPU composites were improved by 130.3 % and 44.2 % respectively.

The PLA-Ag NPs/PU bicomponent nanofiber production for wound dressing applications: Investigation of core/shell displacement effect on antibacterial, cytotoxicity, mechanical, and surface properties

In this study, pure polyurethane (PU) and poly (lactic) acid-silver nanoparticle (PLA-Ag NP) bicomponent nanofibers were successfully obtained alternately by using in the core or shell with coaxial electrospinning. The effects of displacements in the core and shell of fibers on the characterization, antibacterial, and cytotoxicity properties of whole bicomponent fibers were examined in detail. Using PLA-Ag NPs in the core, produced bicomponent mats that were thinner whereas locating PLA-Ag NPs to the shell, obtained bicomponent nanofibers that were more hydrophobic. TEM and FTIR analysis proved that PLA-Ag NPs and pure PU are obtained as a bicomponent structure without mixing with each other. When pure PU was used in the core, bicomponent mats showed high elasticity and strength. As the Ag NPs ratio in the core has increased, the viability of the mouse fibroblast cell line (L929) also has increased. The bicomponent nanofiber with 10% Ag NP in its core has supported cell growth and has shown a high antibacterial effect against Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. This study reported that prepared mats could be used as an antibacterial wound dressing, especially for dry wounds, if renewed every 24 hours.

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.

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.

Breast Implant Capsule: A Murine Model Comparing Capsular Contracture Susceptibility Among Six Breast Implants Available in the Market.

Breast implant capsule development and behavior are mainly determined by implant surface combined with other external factors such as intraoperative contamination, radiation or concomitant pharmacologic treatment. Thus, there are several diseases: capsular contracture, breast implant illness or Breast Implant-Associated Anaplastic Large Cell Lymphoma (BIA-ALCL), that have been correlated with the specific type of implant placed. This is the first study to compare all major implant and texture models available in the market on the development and behave of the capsules. Through a histopathological analysis, we compared the behavior of different implant surfaces and how different cellular and histological properties give rise to different susceptibilities to develop capsular contracture among these devices. A total of 48 Wistar female rats were used to implant 6 different types of breast implants. Mentor®, McGhan®, Polytech polyurethane®, Xtralane®, Motiva® and Natrelle Smooth® implants were employed; 20 rats received Motiva®, Xtralane® and Polytech polyurethane®, and 28 rats received Mentor®, McGhan® and Natrelle Smooth® implants. The capsules were removed five weeks after the implants placement. Further histological analysis compared capsule composition, collagen density and cellularity. High texturization implants showed the highest levels of collagen and cellularity along the capsule. However, polyurethane implants capsules behaved differently regarding capsule composition, with the thickest capsules but fewer collagen and myofibroblasts than expected, despite being generally considered as a macrotexturized implant. Nanotextured implants and microtextured implants histological findings showed similar characteristics and less susceptibility to develop a capsular contracture compared with smooth implants. This study shows the relevance of the breast implant surface on the definitive capsules' development, since this is one of the most differentiated factors that determine the incidence of capsular contracture and probably other diseases like BIA-ALCL. A correlation of these findings with clinical cases will help to unify implant classification criteria based on their shell and their estimated incidence of capsule-associated pathologies. Up to this point, the establishment of additional groups is recommended as nanotexturized implants seem to behave differently to pure smooth surfaces and polyurethane implants present diverse features from macro- or microtextured implants. This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Colorless, Transparent, and High-Performance Polyurethane with Intrinsic Ultraviolet Resistance and Its Anti-UV Mechanism

Polyurethane (PU) is a widely used polymer material that will age under prolonged exposure to ultraviolet (UV) light, shortening the service life. Several methods have been used to prepare the anti-UV PU, including adding nonreactive anti-UV additives, functional fillers, and biological antioxidant molecules. However, the nonreactive anti-UV additives may migrate during long-term use, the functional fillers may damage the mechanical properties and seriously reduce the light transmittance of the sample, and the biological antioxidant molecules will inevitably color the sample. To solve these problems, in this work, a benzotriazole UV absorber (Chiguard R-455) was introduced into the PU molecular chains by in situ polymerization to prepare the nonmigrating intrinsic anti-UV PU sample with high performance and colorless transparency. The anti-UV PU samples exhibit light transmittance of over 88% in the visible range and superior mechanical properties with tensile strength higher than 65 MPa and elongation at break higher than 900%. After 24 h UV irradiation (200 W, 365 nm), the tensile strength and elongation at break of pure PU sample are significantly reduced to only 8.9 and 15.8% of the original one, respectively. On the contrary, the addition of Chiguard R-455 will endow the PU sample with excellent anti-UV performance. After 24 h UV irradiation, the tensile strength (67.2 ± 1.6 MPa) and elongation at break (917.4 ± 30.0%) of PU-0.5% (the content of Chiguard R-455 is only 0.5 wt %) have changed little compared with the sample without irradiation (67.4 ± 3.5 MPa and 919.4 ± 26.5%). Additionally, the anti-UV mechanism of the PU sample is systematically studied. This work provides a feasible method for preparing colorless, transparent, high-performance, nonmigrating intrinsic UV-shielding PU samples, which can be used as a UV light-shielding material in various fields with visible and aesthetic requirements, such as protection fields and wearable products.

Multifunctional nanocomposite coatings for superior anticorrosive, flame retardant and mechanical properties in aerospace components

The addition of manganese disulphide (MnS2), 3-(m-aminophenoxy)propyltrimethoxysilane (APMS), and graphene oxide (GO) has improved the anticorrosion, flame retardant, and mechanical properties of polyurethane (PU) coatings. By using Scanning electron microscopy (SEM)/Energy dispersive X-ray analysis (EDX), Transmission electron microscopy (TEM), Thermal gravimetric analysis (TGA), X-ray photoelectron spectroscopy, and X-ray diffractometry (XRD) techniques, the structural and morphological behaviors of the films such as APMS/MnS2, GO/MnS2, and GO/APMS-MnS2 were studied. The inclusion of these films in the PU matrix resulted in various coating formulations, such as pure PU, PU-MnS2, PU-APMS/MnS2, PU-GO/MnS2, and PU-GO/APMS-MnS2. The result was an 82-fold increase in the dielectric constant of PU at 1 Hz with the addition of just 0.3% GO/APMS-MnS2. Additionally, compared to plain PU, the PU-GO/APMS-MnS2 shown greater flame retardancy with substantial drops in the values of PHRR and THR, or 59% and 54% reductions, respectively. The anticorrosive, hydrophobic, flame retardancy, and mechanical performance of the PU coating are improved on the GO/APMS-MnS2 composite. As evidenced by its water contact angle (WCA) of 166˚, the superhydrophobic behavior is validated. In addition, the coating resistance of PU-GO/APMS-MnS2 was found to be significantly greater (17999.5 kΩ.cm2) than those of the investigated coatings. Similarly, the adhesive strength (15.8 MPa), microhardness (1300 MPa), and tensile strength (198 MPa) of the PU-GO/APMS-MnS2 were observed to be much higher than the other formulations. In light of this, the PU-GO/APMS-MnS2 nanocomposite may be used as a coating material in industrial applications.

Structural control of PEG-intercalating Na-bentonite and its influence on the properties of castor oil-based polyurethane coating

Although controlled-release fertilizer (CRF) is a safer and more efficient strategy to administer nutrients for plant growth, it is still a daunting task to reduce the cost and improve the degradability of the synthetic resin coatings. In this paper, an inorganic/organic composite coating for urea fertilizer was prepared from a biodegradable castor oil-based polyurethane (PU) filled with the layered Na-bentonite (Na-BT), which was ultrasonically treated by a series of green PEG surfactants. Synergistically influenced by various intercalation ability, cation-hosting ability and hydrophilicity of the PEGs, the porous structures of the modified Na-BT (MBT) fillers were simply tuned by varying the Mn molecular weights of the PEGs, resulting in the adjustable water swelling and mechanical properties of the MBT/PU composites. Moreover, it was confirmed that the water swelling property played a critical role in controlling the early stage of nutrient release, and the mechanical properties were important for the longevity of nutrient release from the CRFs. The best MBT/PU composite supported a CRF with a long-term release of 75 % in 38 days, which was much longer than the one based on pure PU (20 days).

Effects of Europium Complex on Thermal and Photoluminescence Properties of Polyurethane-Europium Materials.

A europium complex with double bonds was synthesized with crotonic acid as the ligand and a europium ion as the center ion. Then, the obtained europium complex was added to synthesized poly(urethane-acrylate) macromonomers to prepare the bonded polyurethane-europium materials by the polymerization of the double bonds in the complex and the poly(urethane-acrylate) macromonomers. The prepared polyurethane-europium materials had high transparency, good thermal stability and good fluorescence. The storage moduli of polyurethane-europium materials are obviously higher than those of pure polyurethane. Polyurethane-europium materials exhibit bright red light with good monochromaticity. The light transmittance of the material decreases slightly with increases in the europium complex content, but the luminescence intensity gradually increases. In particular, polyurethane-europium materials possess a long luminescence lifetime, which has potential applications for optical display instruments.