Performance Of Polyurethane Research Articles

Influence of amine chain extenders on morphology and performances of poly(dimethylsiloxane) based poly(urea‐urethane) elastomers

AbstractThe structure, morphology, and performance of polyurethanes are greatly influenced by the structure of chain extenders. In this study, two types of amine chain extenders, 1,3‐bis(3‐aminopropyl)‐1,1,3,3‐tetramethyldisiloxane (BAPD) and isophorone diamine (IPDA), were utilized in the synthesis of poly(dimethylsiloxane) (PDMS)‐based poly(urea‐urethane) elastomers (PDMS‐PUUs). The mechanical properties, morphology, and in vitro oxidative stability of the as‐prepared elastomers were controlled by altering the ratio of BAPD and IPDA. The results indicate that the overall phase mixing of PDMS‐PUUs improves after incorporating of BAPD into the hard segments. The hard segment, composed of IPDA with a rigid structure, plays a crucial role in maintaining the essential mechanical properties of the PDMS‐PUUs. Furthermore, PDMS‐PUUs based on mixed chain extenders exhibit relatively high boundary diffuseness and boundary thickness. Especially, the PDMS‐PUU sample synthesized from BAPD and IPDA with a molar ratio of 1/1 features the highest boundary diffuseness (0.094) and boundary thickness (0.395 nm), consequently displaying some remarkable properties, including enhanced cyclic tensile properties, superior strain recovery (92.6%), a low modulus (8.6 MPa), and high tensile strength (20.3 MPa). PDMS‐PUUs also exhibit good oxidative stability and biocompatibility, implying that the as‐prepared PDMS‐PUUs are proven to be biostable and capable of long‐term implantation.

Thermal stimuli response diphenylmethane diisocyanate‐based polyurethane elastomer via adjustable silicon‐induced distinctive microstructure

AbstractThe segment character of polyurethanes (PUs) determines the micromorphology and properties. The effective segment regulation can customize the favorable performance of PUs. Herein, silicon covalent‐modified polyurethanes (MPUs) were prepared by incorporating diphenylmethane diisocyanate (MDI) and diphenyl silanediol (DPSD) into PU molecules as hard segments via a two‐step method. Distinctive microphase separation structures from sheet morphology to radial sheet or withered flower‐like microdomain were formed by adjusting hydrogen bonding of hard segments and post‐treatment techniques. Thus, with the addition of DPSD in hard segments, the thermo‐optic responses for MPUs occurred due to the different microphase evolution under thermal effect. And with the further addition of DPSD, the effect of thermal stimuli on the transmittance gradually weakened. It was very clear that with increasing the temperature, the transmittance of MPUs showed a gradual increase owing to melting the microcrystals or destroying the ordered accumulation of hard segments. Meanwhile, the high mechanical properties were obtained, higher 15 times tensile strength and more than 100 times elastic modulus than those of pure PU as well as the excellent thermal stability. In sum, this study was of great significance for developing new functionalized PU materials.Highlights Polyurethanes were prepared by inducing modified silicon functionality. The distinctive microphase separation evolution of MPUs was found. Thermal stimuli responses showed a gradual decrease due to different structure. High mechanical properties and thermal stability were also obtained.

The Performance Study of Microstrip Patch Antenna Made of Polyurethane - Oil Palm Empty Fruit Bunch Composite

In this paper, the performance of microstrip patch antenna that is made of fully biodegradable materials has been studied. The polymer resins of Polyurethane as a binder agent were produced using polyol extracted from palm oil while the host composites were made from oil palm empty fruit bunch fiber. The performance of Polyurethane – Oil Palm (PolyOP) Empty Fruit Bunch composite as a microwave dielectric substrate was tested by fabricating microstrip patch antenna on it. The performance of fabricated patch antenna was measured using Vector Network Analyzer (VNA) and is compared with simulation results obtained from High Frequency Structure Simulator (HFSS) simulator. The difference of percentage in resonant frequency, return loss, bandwidth and VSWR between simulation and measurement were found to be 0.4%, 75.2%, 67.9%, and 12.7%, respectively.

Performance of polyurethane and polyurethane nanocomposites modified by graphene, carbon nanotubes, and fumed silica in dry and wet environments

Performance of polyurethane and polyurethane nanocomposites modified by graphene, carbon nanotubes, and fumed silica in dry and wet environments

The Impact of Isocyanate Index and Filler Functionalities on the Performance of Flexible Foamed Polyurethane/Ground Tire Rubber Composites.

The structure and performance of polyurethane (PU) foams are strongly driven by the stoichiometry of the polyaddition reaction, quantitatively described by the isocyanate index. It determines the balance between isocyanate and hydroxyl groups in the reacting system and is affected by the introduction of additional functionalities originated, e.g., from applied fillers. Nevertheless, this issue is hardly taken into account in research works. Herein, the structure and performance of PU/ground tire rubber (GTR) composites differing in their isocyanate index (from 0.8 to 1.2) and prepared with and without considering the GTR functionalities in formulation development were investigated. Incorporating GTR into the PU matrix led to a reduction in average cell diameter (from 2 to 30% depending on the isocyanate index) compared to unfilled foams. However, formulation adjustments did not show a significant impact on cellular structure. The only decrease in open cell content was noted, from 10% for the 0.9 index to 40% for 1.2. Such changes were related to the increasing strength of the PU cellular structure able to maintain inside the increasing amount of carbon dioxide. On the other hand, considering hydroxyl values of GTR noticeably affected the thermomechanical performance of composites. The shift of glass transition temperature (Tg), even by 10 °C for 1.2 isocyanate index, enhanced the performance of materials, which was expressed in an 8-62% drop in the composite performance factor, pointing to the enhanced reinforcing effect resulting from filler incorporation. The stiffening of foams, related to the variations in PU segmental structure, also caused minor changes in the course of thermal degradation of PU/GTR composites due to the inferior thermal stability of hard segments. The obtained results provide important insights into the development of formulations of PU composites filled with materials containing reactive functional groups able to disrupt the stoichiometric balance of the polyaddition reaction.

Synergistic effect of silicon‐containing groups on the self‐healing performance of polyurethanes based on disulfide bonds

AbstractSelf‐healing polyurethanes (PUs) with disulfide bonds and diphenyl silicon groups involved in the soft phases were prepared and studied in this work. The self‐healing efficiencies of PUs are greatly improved by the synergistic effect of diphenyl silicon groups with low surface energy—increasing the distance between two polymer chains, enhancing the mobility of polymer chains, and promoting the migration of sulfur‐containing groups to the damaged sites. The analysis of activation energy for the movement of polymer chains based on dynamic mechanical thermal analysis shows that, the higher contents of disulfide bonds and diphenyl silicon groups, the stronger mobility of polymer chains, and the higher self‐healing performance of PUs. The study of temperature and time dependencies for the healing process at damaged sites indicates that it is composed of the recombination of disulfide bonds and the interpenetration and intertwining of polymer chains. The former can be completed in a shorter time, while the latter in a longer time. Sufficient time of heat treatment at relatively high temperature is necessary to get high self‐healing efficiency. This strategy and the relative results are instructive to design and development of self‐healing PUs.

Synthesis and properties of responsive self-healing polyurethane containing dynamic disulfide bonds

The polymers with pH responsiveness and temperature sensitivity exhibit important applications in many fields. To endow the responsive polymers with self-healing is meaningful work, which contributes to increase their service life and reduce waste of resources significantly. In this research, a series of pH-responsive polyurethanes containing dynamic disulfide bonds and carboxylic acid functional groups were prepared by mixing polycaprolactone diol (PCL), hexamethylene diisocyanate (HDI), 2,2-dimethylolbutyric acid, and bis(2-hydroxyethyl) disulfide. The structure of the polymer was confirmed by some characterization methods such as infrared absorption spectroscopy, Raman scattering spectroscopy, X-ray diffraction, and differential scanning calorimetry. Many performances of the polymer such as the contact angle, thermal stability, mechanics, and self-healing properties can be adjusted by changing the functional units of polyurethanes. The dynamic disulfide bonds in the main chain were observed no harm to the pH response performance, instead which were beneficial to the promotion of heat resistance, tensile properties, and self-healing performance of polyurethane. The elongation at break and the tensile strength are increased by 85.3% and 54.9%, respectively. All the polyurethane exhibited considerable self-healing effects at 110°C, with the highest healing efficiency reaching 93.7%, as a result of the dissociation of hydrogen bonds and the exchange reaction of disulfide bonds.

Fortification performance of polyurethane coating in outdoor historical ironworks

BackgroundIronworks in the tomb of Suleiman Pasha Al-Faransawi (located in the old Cairo, Egypt) were exposed in the open-air are susceptible to various corrosion factors, which be contingent on the environmental conditions wherein the artifacts are displayed and the existence of a protective layer or not. Examinations and analysis were conducted to identify the structure and type of the alloys used in making the decorative ironworks, to identify the manufacturing technique and decoration, and to study the nature of rust compounds. This has been achieved by using metallographic microscopy, X-ray diffraction, and a carbon–sulfur analyzer. Many protection approaches have been worked such as varnishes, waxes, and oils, but they have had many disadvantages. The aim of this paper is to assess the competence of polyurethane coating by using electrochemical measurements (electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization) in the fortification of ironworks exposed in the outdoor environment.ResultsThe results confirmed that the decorative ironworks were manufactured from wrought and gray cast iron. The main corrosion products identified by XRD are goethite, akageneite, and maghemite. Lead oxide hydrate refers to old lead paints (red primer) which have been applied to protect the ironworks. Quartz and calcite are the products of heavy dust particles that covered the surface.ConclusionThe data proved that the polyurethane is acting as a good protective coating for the decorative ironworks exposed in an uncontrolled environment. The 2% is considered as the recommended dose for this polymer for the minimum corrosion rate of the ironworks.

Rolling reliability of polyurethane and polyurethane-acrylic ICAs interconnections on printed stretchable electronics

In this study, bending reliability of the surface mounted devices (SMD) attached using isotropic conductive adhesive (ICAs) on screen printed stretchable devices polyurethane substrate are investigated. The performance of polyurethane and polyurethane-acrylic ICAs and the impact of rolling speed are studied. The rolling test was performed using the customized automatic rolling test device. It was found that the polyurethane-acrylic blend gives poorer adhesion with the silver conductor and very high cohesive force. The polyurethane resin brings adhesive high adhesive force with the silver conductive layer while lower adhesion with the Tin surface of the SMD, and it exhibited poorer cohesive force. The resistance of all samples experienced a steady and slow increase period before it accelerated to failure. During the slow and steady increase phase, the increased resistance was mainly from the conductive layer, whereas during the dramatic increase phase, it was mainly from the ICA connected area. The increased rolling speed had accelerated the resistance evolution process and lowered the samples' reliability severely. It also lowered the adhesion of the polyurethane-acrylic blend with the ink layer and lowered cohesive force of polyurethane ICA.

Mechanical Assessment and Hyperelastic Modeling of Polyurethanes for the Early Stages of Vascular Graft Design.

The material design of vascular grafts is required for their application in the health sector. The use of polyurethanes (PUs) in vascular grafts intended for application in the body appears to be adequate due to the fact that native tissues have similar properties as PUs. However, the influence of chemical structure on the biomechanics of PUs remains poorly described. The use of constitutive models, together with numerical studies, is a powerful tool for evaluating the mechanical behavior of materials under specific physiological conditions. Therefore, the aim of this study was to assess the mechanical properties of different PU mixtures formed by polycaprolactone diol, polyethylene glycol, and pentaerythritol using uniaxial tensile, strain sweep, and multistep creep-recovery tests. Evaluations of the properties were also recorded after samples had been soaked in phosphate-buffer saline (PBS) to simulate physiological conditions. A hyperelastic model based on the Mooney–Rivlin strain density function was employed to model the performance of PUs under physiological pressure and geometry conditions. The results show that the inclusion of polyethylene glycol enhanced viscous flow, while polycaprolactone diol increased the elastic behavior. Furthermore, tensile tests revealed that hydration had an important effect on the softening phenomenon. Additionally, after the hydration of PUs, the ultimate strength was similar to those reported for other vascular conduits. Lastly, hyperelastic models revealed that the compliance of the PUs showed a cyclic behavior within the tested time and pressure conditions and is affected by the material composition. However, the compliance was not affected by the geometry of the materials. These tests demonstrate that the materials whose compositions are 5–90–5 and 46.3–46.3–7.5 could be employed in the designs of vascular grafts for medical applications since they present the largest value of compliance, ultimate strength, and elongation at break in the range of reported blood vessels, thus indicating their suitability. Moreover, the polyurethanes were revealed to undergo softening after hydration, which could reduce the risk of vascular trauma.

Polyurethanes: Design, synthesis and structure-property behavior of versatile materials

Polyurethanes are one of the most important classes of polymeric materials. This is mainly due to the availability of a very large number of inherently different starting materials that allows the design and synthesis of polyurethane based materials with a wide range of properties for numerous applications. In this short review, important physical and chemical factors and parameters that have a significant effect on the properties of polyurethanes are discussed. Critical contribution of hydrogen bonding on the structure-morphology-property behavior of these materials was emphasized by both experimental data and molecular simulation studies. Influence of the chemical structures, solubility parameters and molecular weights of the soft and hard segments on morphology and properties were discussed. Important issues regarding the reaction chemistry, synthetic method used and thermal history on structure and performance of polyurethanes were explained. We hope this article, which is prepared to celebrate the 100th anniversary of Polymer Science, will be useful to those who are newcomers to the field, but also to the experienced researchers to better understand the structure-property behavior of polyurethanes and tailor-design novel structures for various applications.

Research on structure and performance of polyurethane elastomer/superfine talcum powder composite

The structure and performance of polyurethane elastomer/superfine talcum powder composites were investigated by X ray diffraction ( XRD), FTIR spectra and thermogravimetric analysis ( TG - DTA, DSC ). The results showed that talcum powder and polyurethane elastomer formed com pound structure of heterogeneous nucleation when the content of superfine talcum powder was right(such as 15% ), which caused the soft segments, hard segments and talcum powder of polyurethane elastomer to form interactional congeries system and the integrated mechanical properties and thermostability of polyurethane elastomer were improved.

Measuring the Microphase Separation Scale of Polyurethanes with a Vibration-Induced Emission-Based Ratiometric "Fluorescent Ruler".

Polyurethanes (PUs) are a very attractive type of segmented polymer with unique mechanical properties derived from thermodynamic incompatibility between flexible soft segments and hard segments. The performance of PUs is closely related to their microphase separation structures, in which the hard domains serve as physical cross-linking points in the soft matrix. Studying the microphase separation of PUs in a facile manner is thus of great significance but challenging due to the complexity of the internal structures of PUs. N,N'-disubstituted-dihydrophenazine (DPAC) derivatives, the typical molecules featured with vibration-induced emission (VIE) attribute, can emit fluorescence varying with surrounding environment. In this proof-of-concept work, a series of DPAC derivatives were employed as built-in ratiometric "fluorescent rulers" to measure the degree of microphase separation in PUs modulated by temperature variation. The fluorescence of selected DPAC-doped PU films is dependent on the temperature, providing a theoretical basis for this concept. The feasibility of these fluorescent rulers was further validated by the small-angle X-ray scattering (SAXS) analysis. The SAXS curves show significant change in q range of 0.02 to 0.15 Å-1 with the variation in temperature, showing the changes in the internal microstructure. The polydisperse hard sphere model analysis of the scattering data revealed that the volume fraction of hard spheres has a defined relationship with the fluorescence intensity ratio of orange-red light and blue light, thereby demonstrating a novel fluorimetry method for measuring and monitoring the microphase separation of polyurethanes.

High-performance polyurethane nanocomposites based on UPy-modified cellulose nanocrystals

Densely H-bonding assemblies are the key strategy found by nature to enhance the rupture strength of natural polymers without sacrificing their toughness, such as spider silk, while it still remains a great challenge using such intriguing strategy to prepare high-performance synthesized polymer or biopolymer enhanced polymer nanocomposites. To address this challenge, we report here a bio-inspired strategy using densely H-bonding assembly for facile fabrication of high performance polyurethane (PU) nanocomposites reinforced by hydroxyl-rich cellulose nanocrystals (CNCs) functionalized with 2-ureido-4-[1 H]-pyrimidinone motifs (CNC-UPy) containing self-complementary hydrogen bonds. These PU/CNC-UPy nanocomposites showed remarkably improved mechanical strength without sacrificing the elongation at break and toughness compared to pure PU matrix. Differential scanning calorimetry(DSC) results indicated that CNC-UPy could induce the formation of long range ordering of hard segment domains, due to the strong hydrogen bonding interactions between UPy motifs attached on CNC-UPy and PU matrix. Furthermore, wide angle X-ray diffraction (WAXD) measurements demonstrated that the strain-induced crystallization (SIC) was enhanced significantly by introducing CNC-UPy into PU, leading to a large stress at break. The enhanced interfacial H-bonding interactions between CNC and PU though UPy anchoring could overcome the inherent trade-off between the stiffness and toughness of polymer composites. The proposed bio-inspired strategy using densely H-bonding assembly will be with more extensive application prospects.

Development and Characterization of Anticorrosion and Antifriction Properties for High Performance Polyurethane/Graphene Composite Coatings

This work contributes to the development and characterization of the corrosion resistance and antifriction properties of high performance polyurethane (PU)/graphene (Gr) composite coating. In this study, PU composite coatings containing 0, 2, 4 and 8 wt.% of Gr were prepared and evaluated using various corrosion and mechanical tests, namely electrochemical impedance spectroscopy, salt spray tests, cross-cut tape tests and dynamic mechanical analysis. Antifriction properties of the coatings were evaluated using a tribometer with a ball-on-disc mode at room temperature. The corrosion resistance and adhesion property of the PU coatings were found to be enhanced by adding 4 and 8 wt.% of Gr. The coefficient of friction revealed that the antifriction properties of the PU/Gr composite coatings were 61% lower than those of the conventional coating when the Gr content was increased to 8 wt.%.

改性纳米SiO<sub>2</sub>提高聚氨酯封堵性能研究

改性纳米SiO<sub>2</sub>提高聚氨酯封堵性能研究

Improvement, the Performance of Polyurethane (PUR), Y-290 Resin as Coating of Oil Pipeline by Using Multi-Walled Carbon Nanotubes (MWCNTs)

In this study, polyurethane epoxy-Y290 (PUR-Y290) as a matrix material was reinforced by 1%MWCNTs. Polyurethane is a thermoset polymer and using for several applications particularly as coatings of gas and oil pipeline. Polyurethane uses as a liquid coating against the corrosion, and that is caused by the direct exposure for long periods of UV irradiation and humidity. The nanocomposites were prepared by adding 1wt% MWCNTs to polyurethane and mixed by using an ultrasound mixer. Polyueethane-1%MWCNTs composite sample was exposed to accelerate weathering (UV irradiation coming from sunlight, moisture, and salt water spray) during the exposure to different durations 6 months, 12 months and 24 months. Exposed and unexposed samples were investigated and evaluated by thermal and mechanical tests.It was found that the incorporation 1.0%wt of MWCNTs filler, enhanced the thermal stability and improved the mechanical properties during the exposure for long-term life to accelerated weathering conditions, compared with polyurethane coating without MWCNTs filler. These results indicated that polyurethane (liquid coating) nanocomposites have a higher resistance to environmental condition and give more protective against corrosion of oil pipelines and applied as coatings by spray method to protect the oil pipeline surfaces from environmental conditions.

Engineering Performance of Polyurethane Bonded Aggregates

In this paper the engineering performance of polyurethane (PUR) bonded aggregate were studied. The engineering performance, including compressive and flexural mechanical properties, void ratio, and coefficient of permeability were determined through laboratory tests. Moreover, the effects of two different curing conditions on the compressive strength properties of a PUR bonded aggregate were also evaluated. The compressive strengths of PUR bonded aggregates were found to be lower than that of conventional porous concrete, which is a commonly used cushion material. However, experimental results indicated a higher void ratio and coefficient of permeability, lower elasticity modulus, better toughness, and stronger adaptability to flexural deformation compared to porous concrete. Consequently, PUR bonded aggregate is a better solution than porous concrete when used as the cushion material of a geomembrane surface barrier for a high rock-fill dam.DOI: http://dx.doi.org/10.5755/j01.ms.23.2.15798

Effects of Ionic Group on the Shape Memory Performance of Polyurethane

Ionic polyurethane (IPU) was synthesized as shape memory materials. Poly (tetramethylene ether) glycol with 2000g/mol number average molecular weight were used as soft segment, 4,4-methylenebis (phenyl isocyanate), and 1,2-dihydroxy-3-propanesulfonic acid salt were used to compose the segment of SMP materials. The structure and properties of these IPU films were characterized by Fourier Transform infrared, X-ray diffraction, Thermal gravimetric analysis and Differential scanning calorimeter. The results showed that the glass transition temperature of the IPU increased with the increase of hard segment content. The physical properties in terms of swelling property, water absorption and ion-exchange capacity increased with the improving of sulfonic group content in IPU. The shape memory property of IPU exhibited that the shape fixity ratio and recovery rate improved remarkably with the increase of hard segment content.

Synthesis of Tung Oil Monoglyceride

Tung oil monoglyceride (TOM, also called eleostearic acid monoglyceride, EAM) is a derivative of a Chinese renewable natural resource Tung oil and it is a potential monomer for polyurethane which can improve the performances of polyurethane coating. The synthesis of TOM by esterification of eleostearic acid and solketal with catalyst p-toluenesulfonic acid was investigated. Experimental results showed that the suitable synthetic conditions for TOM were as follows: a. for the esterification of eleostearic acid and solketal, with regard to eleostearic acid 0.02 mol with concentration 0.5 mol/L, mole ratio of eleostearic acid to solketal 1:1.5, catalyst p-toluenesulfonic acid dosage 5% (wt, calculated by eleostearic acid), dehydrating agent xylene, and reaction time 3 h under refluxing. The conversion of eleostearic acid peaked at 99.1% under the optimal conditions and the intermediate, solketal eleostearate was obtained. b. after deprotection under acidic condition for 4 h at 35 °C to remove protection agent acetone which was employed in the synthesis of solketal, the product TOM would obtained with yield 93.6%.