Polyurethane Content Research Articles

Effect of void ratio and rubber particles on the noise reduction mechanism and comprehensive performance of porous elastic road surface

ABSTRACT Porous Elastic Road Surface (PERS) is recognised as a pavement with excellent noise reduction ability. However, the mechanisms and field test evaluations of noise reduction for PERS have been not sufficiently explored. This study aims to investigate the effect of void ratio and rubber particle content on the noise reduction of PERS. PERS mixtures were prepared with varying void ratios and rubber particle contents, and subsequently tested by acoustic performance tests. The results reveal a decrease in sound pressure level, noise energy and dynamic modulus with increasing void ratio or rubber particle content. Conversely, the sound absorption coefficient presents an inverse relationship. The presence of interconnected voids significantly influences the noise reduction ability of PERS. However, excessive rubber particles can lead to decreased sound absorption coefficient. Furthermore, an optimised composition of PERS balancing road performance and noise reduction is identified. It is concluded that a PERS mixture featured with 25% void ratio, 4.5% polyurethane content and 20% rubber particle content exhibits good road performance and noise reduction ability. Notably, field tests indicate the sound pressure level reduce 9.1 dB(A) compared with traditional asphalt pavement. It is expected this study can provide insights for the development and implementation of PERS.

Effect of Polyurethane Content on the Performance of Ballasts under Static and Cyclic Loading

Effect of Polyurethane Content on the Performance of Ballasts under Static and Cyclic Loading

Microstructure and dynamic behaviours of polyurethane-cured sea sand under traffic–load–induced stress path

Employing sea sand as fill material for roadbeds presents significant challenges due to its naturally high dispersibility and low bearing capacity, which contribute to substantial settlement deformations under traffic load impacts. In this investigation, a two-component polyurethane was applied to enhance mechanical properties of sea sand. Alterations in the microstructure and dynamic behaviours of the polyurethane-cured sea sand were observed via Scanning Electron Microscopy (SEM) and hollow cylindrical torsional shear testing. It was found that polyurethane is incorporated into the sea sand as adhesives between particles, attachments on the particles and floating adhesives. With an increase in polyurethane content, a transition from a granular to a solid state in the sand was noted, accompanied by a progressive improvement in structural integrity. This resulted in an enhanced bonding effect at interparticle contacts with diminishing relative particle movements during shearing, leading to an increase in the critical dynamic stress ratio and a decrease in the maximum damping ratio, with both ratios being higher in cured sea sand with lower polyurethane content compared to that with higher content. Additionally, high polyurethane content induced strain hardening in the cured sea sand, resulting in a higher maximum dynamic shear modulus in low-content cured sea sand compared to high-content. Furthermore, the dynamic shear modulus ratio in sea sand with high polyurethane content was found to increase with the number of vibrations.

A method for synthesis of waterborne polyurethane using an eco-friendly surfactant

In general, waterborne polyurethane molecular chains containing hydrophilic groups usually require extended drying times to achieve sufficient film formation, thereby increasing energy consumption. The preparation of high-solid content waterborne polyurethane has attracted significant attention in both scientific research and industrial applications. The primary challenges associated with increasing the solid content of waterborne polyurethane are poor fluidity and inadequate storage stability. In this study, two surfactants, sodium lauryl sulfate and polyethylene glycol, were incorporated into the emulsification process of waterborne polyurethane to achieve a solid content of more than 50 %. The effect of different addition levels ranging from 1 to 5 wt% on viscosity, storage stability, physical and mechanical properties, thermal properties, and surface morphology of dried WPU films was further investigated. Waterborne polyurethane dispersion without surfactants solidified within a month, whereas those with surfactants remained stable for up to four months. Furthermore, the addition of sodium lauryl sulfate and polyethylene glycol significantly reduced the viscosity of waterborne polyurethane to 6–80 P and 3–17 P, respectively. Compared to SDS, PEG offers several advantages, including non-toxicity, biocompatibility, and solubility in various solvents. The addition of 1 wt% polyethylene glycol resulted in a stable waterborne polyurethane dispersion, achieving a solids content above 50 % with a viscosity of 17 P. This fundamental study establishes a pathway for preparing high solid content WPU using environmentally friendly surfactants.

Biopolymer Compositions Based on Poly(3-hydroxybutyrate) and Linear Polyurethanes with Aromatic Rings-Preparation and Properties Evaluation.

Polymer biocompositions of poly(3-hydroxybutyrate) (P3HB) and linear polyurethanes (PU) with aromatic rings were produced by melt-blending at different P3HB/PU weight ratios (100/0, 95/5, 90/10, and 85/15). Polyurethanes have been prepared with 4,4'-diphenylmethane diisocyanate and polyethylene glycols with molar masses of 400 g/mol (PU400), 1000g/mol (PU1000), and 1500 g/mol (PU1500). The compatibility and morphology of the obtained polymer blends were determined by infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC). The effect of the polyurethane content in the biocompositions on their thermal stability and mechanical properties was investigated and compared with those of the native P3HB. It was shown that increasing the PU content in P3HB-PU compositions to 10 wt.% leads to an improvement in the mentioned properties. The obtained results demonstrated that the thermal stability and mechanical properties of P3HB were improved, particularly in terms of increasing the degradation temperature, reducing hardness, and increasing impact strength. The best thermal and mechanical properties were shown by the P3HB-PU polymer compositions containing 10 wt.% of polyurethane modifiers, especially PU1000, which was also confirmed by the morphology analysis of these biocompositions. The presence of polyurethanes in the resulting polymer biocomposites decreases their glass transition temperatures, i.e., makes the materials more flexible. The resulting polymer biocompositions have suitable mechanical properties and thermal properties within the processing conditions for the predicted application as biodegradable, short-lived products for agriculture.

Supercritical CO2 extrusion foaming of highly open-cell poly(lactic acid) foam with superior oil adsorption performance

Addressing marine oil spills and industrial water pollution necessitates the development of eco-efficient oil-absorbing materials. With increasing concern for the environment, there is a consensus to decrease the use of petroleum-based polymers. Herein, lightweight poly(lactic acid) (PLA) blend foams with varying thermoplastic polyurethane (TPU) content were fabricated via a solvent-free, eco-friendly supercritical carbon dioxide (scCO2) extrusion foaming technology. The incorporation of TPU significantly enhanced the crystallization rate of PLA, with the semi-crystallization time of PT30 and PT50 blends at 105 °C exhibiting a reduction of 77.2 % and 47.9 %, respectively, compared to neat PLA. The resulting foams exhibited an open-cell structure with excellent selective oil adsorption capabilities. Notably, the PT30 foam achieved a remarkable maximum expansion ratio of 36.0, while the PT50 foam attained the highest open-cell content of 96.2 %. The PT50 foam demonstrated an outstanding adsorption capacity, spanning from 4.7 to 18.8 g/g for diverse oils and solvents, with rapid adsorption kinetics, reaching 94.9 % of the equilibrium adsorption capacity for CCl4 within just 1 min. Furthermore, the PT50 foam retained 95.2 % of its adsorption capacity for CCl4 over 10 adsorption-desorption cycles. This study presents a scalable and sustainable approach for large-scale production of high-performance, bio-based foams, facilitating efficient oil-water separation.

Preparation of a bio-based PU/EP IPN concrete adhesive with optimized performance and decent adhesion

An adhesive serves as a vital tool in construction, repair, and rehabilitation projects. Typically crafted from polymer materials such as epoxies or polyurethane latex, it facilitates the creation of resilient bonds between a variety of surfaces, ranging from concrete-concrete and metal-concrete to concrete-composites. However, employing epoxy or polyurethane individually as adhesives often demonstrate insufficient performance and weak interfacial adhesion during service. In this study, an adhesive combining polyurethane and epoxy was synthesized, featuring an interpenetrating polymer network (IPN) structure. This innovative agent was created using polyols sourced from soybean oil and a commercial epoxy resin. By tuning the infusion of polyurethane content, the resultant resin exhibited favorable flowability in civil applications, simultaneously improved strength and toughness due to the IPN structure, and outstanding thermal stability. Notably, the incorporation of 20 wt% polyurethane yielded a polymer with a remarkable tensile strength of 35.9 MPa. Additionally, the bonding adhesion of the prepared resins on concrete specimens was investigated through splitting tensile test and shear strength test. The study explored the influences of polyurethane content, concrete strength, and adhesive layer thickness on interfacial bonding strength. The introduction of an IPN structure within the PU-20 agent proved advantageous for enhancing the bonding adhesion of the concrete, resulting in remarkable interfacial tensile and shear strengths of 4.56 MPa and 21.73 MPa, respectively.

Polyurethane modified asphalt mixture incorporating waste glass with a wide particle size range: Preparation and performance evaluation

Increasing the utilisation rate of waste glass in asphalt mixtures, especially that with a wide range of particle sizes, is of great importance to resource recycling, while it may bring drawbacks to the engineering performance of asphalt mixtures. Incorporating polyurethane (PU) as a modifier can enhance asphalt mixture's performance, but there is limited research considering the usage of waste glass as aggregates. In this study, PU modified asphalt mixtures were prepared, incorporating waste glass particles ranging in size from 2.36 mm to 9.5 mm as a portion of the aggregates. Optimal preparation methods and mix designs for the PU-modified asphalt binder were determined through a series of tests designed based on Orthogonal method. The performances of the PU-modified asphalt binders were then evaluated to guide the selection of the optimal preparation method and mix design. PU-modified waste glass asphalt mixtures were then prepared and their engineering performances were assessed at various glass-to-aggregate ratios. The results show that scheme PU-1 with a shearing temperature of 140°C, a shearing time of 10 min, a PU content of 10% and a compatibiliser content of 2% is suggested for preparing the PU-modified asphalt binder, which shows the best performances due to superior chemical modification and compatibility. Higher glass content decreases the high/low-temperature performance, but it can be improved by adding silane coupling agent or hydrated lime, with the latter showing better results. The incorporation of glass particles has little impact on anti-sliding performance, and asphalt mixtures maintain excellent anti-sliding properties up to a 20% replacement rate. Overall, the performance of the asphalt with waste glass up to 15% can meet the specification requirements. This novel approach offers a potential solution to enhance the incorporation of waste materials in asphalt construction, contributing to sustainable and environmentally-friendly road construction.

Self‐healing waterborne fluorinated polyurethane‐acrylate based on photoreversible reaction and hydrogen bonds

AbstractThe development of self‐healing materials is an effective strategy to improve the service life of polymer materials. In this study, self‐healing waterborne fluorinated polyurethane‐acrylate (WFPUA) containing UV‐responsive coumarin groups was prepared by Pickering emulsion polymerization using modified cellulose nanocrystal as a stabilizer. The effect of double bond‐terminated waterborne polyurethane content on emulsion polymerization and latex film properties was mainly studied. Due to the dynamic reversibility of the coumarin groups and the synergistic effect of hydrogen bonds, the optimized sample (WFPUA‐30) had excellent mechanical properties and self‐healing properties. The tensile strength was 5.24 MPa and the elongation at break was 267%. The self‐healing efficiency of tensile strength and elongation at break after 6 h of repair was 86.52% and 93.20%, respectively. In addition, due to the presence of fluorine‐containing groups, the water and oil contact angles of the latex film could reach 101.7° and 82.1°, respectively. This work broadens the way for the manufacture of self‐healing and multifunctional waterborne polyurethane‐acrylates. © 2024 Society of Industrial Chemistry.

Experimental study of polyurethane cement composite–reinforced soft soil in the thawed layer in permafrost regions

Permafrost degradation induces a large number of thawed layers that have high water content, low bearing capacity, and high compressibility, which threaten the stability of infrastructure in permafrost regions. How to reinforce the soft layers of thawed permafrost is very essential for maintaining and repairing such infrastructure. This study investigates the reinforcement effect and mechanism of a polyurethane cement composite (PUC) on the soft soil in the thawed layer (SSTL) of permafrost through mechanical and microscopic tests. The experimental results indicate that the unconfined compressive strength (UCS) of the SSLT initially increases and then decreases with increasing hydrophilic polyurethane (WPU) content, while it increases with higher polymer cement content (PMC). The UCS of the SSLT reinforced with 10% WPU increases by 41.96% and 18.75% in the early and late stages, respectively, compared to a SSLT sample without added WPU at a moisture content of 40%, while the cohesion of the SSLT increases by 7.74%, and the internal friction angle increases by 29.48%. A microscopic analysis reveals that the PUC significantly enhances the microstructure of the SSLT through intricate physical and chemical reactions. PUC-reinforced SSLT provides a new way to address the settlement and deformation that adversely affect subgrade in permafrost regions.

Study on the anti-aging properties of organic attapulgite (OATT) and polyurethane (PU) composite-modified asphalt

Study on the anti-aging properties of organic attapulgite (OATT) and polyurethane (PU) composite-modified asphalt

Unconfined mechanical properties and micromechanism of short-age recycled aggregate from road solid waste modified by waterborne polyurethane

In recent years, road waste treatment has become a hot topic, and how to solve and utilize these solid wastes is becoming an interesting research field. In order to explore the mechanical modification effect of waterborne polyurethane (PU) on short age road solid waste recycled aggregate, unconfined compression test and scanning electron microscope test were carried out on samples with different dry density and PU content. The dry density was 1.6 g cm−3, 1.7 g cm−3 and 1.8 g cm−3, and the PU content was 0%, 3%, 4%, 5% and 6%, respectively. The tested results show that, the strength of recycled aggregate (RA) increases with the increase of dry density. PU improves the strength and ductility of recycled aggregate (RA), and the residual strength and peak strength of RA increase with the increase of PU content. The peak strength and residual strength of waterborne polyurethane improved recycled aggregate (WPRA) increase with the increase of dry density, too. Polyurethane forms a three-dimensional network structure by film shape and linear shape, and its network structure can provide cohesion and effectively inhibit the crack propagation of the sample. The results demonstrate that adding appropriate amount of PU can effectively improve the mechanical properties of RA, which provides a technical reference for the recycling of RA.

Photomechaelectric Nanogenerators with Different Photoisomers and Dipole Units for Harvesting UV Light Energy.

To date, transforming environmental energy into electricity through a non-mechanical way is challenging. Herein, a series of photomechaelectric (PME) polyurethanes containing azobenzene-based photoisomer units and ionic liquid-based dipole units are synthesized, and corresponding PME nanogenerators (PME-NGs) to harvest electricity are fabricated. The dependence of the output performance of PME-NGs on the structure of the polyurethane is evaluated. The results show that the UV light energy can directly transduce into alternating-current (AC) electricity by PME-NGs via a non-mechanical way. The optimal open-circuit voltage and short-circuit current of PME-NGs under UV illumination reach 17.4V and 696µA, respectively. After rectification, the AC electricity can be further transformed into direct-current (DC) electricity and stored in a capacitor to serve as a power system to actuate typical microelectronics. The output performance of PME-NGs is closely related to the hard segment content of the PME polyurethane and the radius of counter anions in the dipole units. Kelvin probe force microscopy is used to confirm the existence of the PME effect and the detailed mechanism about the generation of AC electricity in PME-NGs is proposed, referring to the back and forth drift of induced electrons on the two electrodes in contact with the PME polyurethanes.

Amplification Ratio of a Recycled Plastics-Compliant Mechanism Flexure Hinge

This research focuses on the fabrication of plastic flexure hinges from diverse plastics such as ABS, PP, HDPE, and LDPE. To enhance hinge efficiency, the recycling ratios are also investigated. The amplification ratio of different recycle ratios and plastic types are measured. The results show that the input and output displacements of all PP, ABS, and HDPE hinges are linear. The presence of recycled plastics has no impact on this basis. The pure PP, ABS, and HDPE flexure hinges achieve the highest amplification ratios of 5.728, 8.249, and 5.668. The addition of recycled plastics reduces the amplification ratio. This decrease in the amplification ratio, however, is small. At a 25% recycle ratio, the PP, ABS, and HDPE flexure hinges have 12%, 13.3%, and 21.7% lower amplification ratios than the pure plastic hinges. Furthermore, the utilization of recycled plastics may lessen the need for new plastic made from raw materials. With the PP flexure hinge, a maximum input value of 157 µm could result in an output value of 886 µm. At a maximum input value of 115 µm, the ABS flexure hinge could achieve an output value of 833 µm. Finally, a maximum input value of 175 µm might result in an output value of 857 µm when using the HDPE flexure hinge. The average amplification ratio values for all recycling ratios for PP, ABS, and HDPE flexure hinges are, respectively, 5.35, 7.60, and 5.02. The ABS flexure hinge frequently outperforms the PP and HDPE flexure hinge in terms of amplification ratios. Among these plastics, HDPE flexure hinges have the lowest amplification ratio. In general, increasing the thermoplastic polyurethane (TPU) content of the LDPE/TPU blend increases the amplification ratio. The cause could be the TPU’s high compatibility with the LDPE polymer. The LDPE/TPU blend hinge offers a broader range of the amplification ratio of 2.85–10.504 than the PP, ABS, and HDPE flexure hinges. It is interesting that changing the blend percentage has a much greater impact on the amplification ratio than changing the recycling ratio. The findings broaden the range of applications for plastic flexure hinges by identifying optimal plastic types. The impact of the hinge shape on the performance of the injected plastic flexure hinge might be studied in further research.

Polyurethane-based composite binder for poroelastic road surface: composition, preparation and properties

To address the high cost and poor water stability of polyurethane (PU) binder used in poroelastic road surface (PERS), a type of PU-based composite binder prepared at room temperature was proposed by using PU as the main ingredient, emulsified asphalt (EA), cement, and defoamer as auxiliary agents. The stabilities of different types of polyurethane-emulsified asphalt (PU-EA) blend systems were investigated and the mix composition of the PU-EA blend system was determined through molecular dynamics (MD) simulations. The interaction mechanisms of all components of the PU-based composite binder were revealed by microscopic measurements through Fourier transform infrared (FTIR) spectroscopy and fluorescence microscopy (FM). The strength and water stability of the PERS mixture bound by the PU-based composite binder were evaluated by the indirect tension (IDT) test and the Cantabro abrasion test. The results showed that the stability of the polyether polyurethane (PEUR)-cationic emulsified asphalt (CEA) blend system was the best, and the potential energy of the PU-EA blend system was the lowest when the PU content was around 50 wt%. Both physical and chemical reactions occurred simultaneously in the polyurethane-emulsified asphalt-cement (PU-EA-C) blend system's components. The calcium silicate hydrate (C-S-H) enhanced the crosslinking gel properties of the PU-EA-C blend system. Cement improved the performance of the PERS mixture in a more efficient way than the PU. When the PU-based composite binder composed of 50 wt% PU, 41 wt% EA, 9 wt% cement, and 0.5 wt% defoamer was used, the water stability and strength performance of PERS mixture were the best. The material cost of the suggested PU-based composite binder was nearly half that of commonly used PU, while the material cost of the PERS mixture was reduced by 25%. These findings would serve as useful references for the promotion and application of PERS pavement.

Synthesis and Characterization of Cresol based Benzoxazine–Polyurethane Copolymer for Anti-corrosion Performance of Mild Steel

The cresol based polymeric materials were synthesized by using benzoxazine and polyurethanes as copolymer. Three copolymers were synthesized by varying the quantity of polyurethane content and studied their corrosion inhibition properties. The synthesized monomer, which has cresol as the center core was characterized by the NMR, FT-IR and UV-visible spectroscopic methods. All the obtained benzoxazine polymers were also analyzed by the FT-IR and UV-visible spectroscopy. In relation to corrosion inhibition studies, Tafel and impedance experiments were conducted, revealing that benzoxazine-polymer with a higher polyurethane content has improved anti-corrosive characteristics. Additionally, the physical properties of the materials were also studied such as water absorption and gel content studies. Furthermore, the density functional theory calculation was also carried out for the monomer, which explores the better results that are matched with the other experimental studies.

Preparation and Performance of Silicone Rubber Composites Modified by Polyurethane.

Silicone rubber composites with good comprehensive properties modified with polyurethane were obtained through mixing and vulcanizing methods. Firstly, the polyurethane prepolymer with double bonds was prepared by polytetrahydrofuran glycol (PTMG, Mn = 1000), isophorone diisocyanate (IPDI), and 2-hydroxyethyl methacrylate (HEMA). The prepolymer was then added to the silicone rubber compounds to prepare silicone rubber composites, combining the excellent properties of polyurethane with the silicone rubber materials. The effects of polyurethane content on the mechanical properties, insulation, hydrophobicity, thermal stability, and flame retardancy of composites were studied in detail. The results showed that the silicone rubber composites not only have good hydrophobicity, thermal stability and flame retardant properties, but the addition of polyurethane significantly improves the tensile strength at room and low temperatures and the volume resistivity of the materials. The tensile strength increased by 32.5%, and the volume resistivity nearly doubled. The excellent electrical insulation, high hydrophobicity and good mechanical properties make the silicone rubber composites appropriate for use in the field of polymeric house arresters.

Preparation and performance investigation of high solid content flame retardant waterborne polyurethane

AbstractTo improve the flame retardancy and solid content of waterborne polyurethane (WPU), AOT, and AOD series of WPU were synthesized and characterized. Carboxylic acid/nonionic composite units were used as hydrophilic groups, and OP550/THPO and OP550/DOPO‐HQ combinations were used as flame retardant modifiers, respectively. The results revealed that the flame retardant‐modified WPU emulsions still had excellent dispersion, stability, and fluidity. The UL‐94 rating of modified WPU could reach V‐0, and the AOD series samples had better flame retardancy than the AOT series, where AO10D3‐WPU containing 3% DOPO‐HQ had an limiting oxygen index value up to 30.5%. Besides, the peak heat release rate and total heat release of AO10D3‐WPU were respectively decreased by 32% and 34%, compared with the control sample in the conical calorimetric test. The TGA, TG‐IR, and SEM‐EDS exhibited that the flame retardants functioned in the condensed phase by promoting carbon formation. The tensile strength of AOT series samples was excellent with a range of 15.84–27.47 MPa, while the elongation at break of AOD series samples was relatively high with a distribution of 850.8%–913.11%, which could be selected to suit the needs of different application scenarios.

Microplastic on Mountain Trails—a Case Study from the Carpathian and Sudetes Mountains in Poland

Microplastics are becoming an increasingly common pollutant that can pose a threat to living organisms. The aim of this research was to determine the amount, type, and diversity of microplastics along mountain trails. The study includes three mountain trails, differing in terms of length, difficulty, and number of visitors. The trails were located in the massif of Babia Góra, in the Kościeliska Valley, and Izerska Meadow. During the research, microplastics were determined in snow during the winter period. The research shows high microplastic contamination along the trails. The study area was characterized by the highest content of polyurethane, polyethylene terephthalate, polyethylene, and polypropylene. The tiniest plastic below 0.5 mm dominated in all the sampling points, with a small share of sizes within the range of 3.1–4.0 mm and 4.1–5.0 mm. The isolated microplastics varied in color and shape. The conducted analyses confirm that easier, more frequented trails are characterized by a higher content of microplastics. Trails to Babia Góra, which are more demanding, are characterized by a different composition of microplastics as well as a variety of microplastics in terms of size, shape, and color. In addition, the lower-lying fragments of the examined trails were the most heavily contaminated with microplastics. The results indicate the need for further research on microplastic contamination of the soil environment along mountain trails.

Study on the Influence Factors of the Dynamic Property of the Polyurethane Mixture with Dense Gradation

Similar to the asphalt mixture, the polyurethane (PU) mixture’s performance and characteristics are dependent on many variables. In this study, six variables, including aggregate gradation (limestone and basalt), aggregate type, PU type, PU content, and curing condition, and several parameter analyzing methods were chosen to determine the effect of variables on the dynamic property, rheological property, and rutting resistance of the PU mixture. The limestone aggregate gradation exhibited a substantial effect on the dynamic property, rheological property, and rutting resistance of the PU mixture; the basalt aggregate gradation exhibited significant influence on the dynamic property and rutting resistance, but a moderate effect on the rheological property. The aggregate type could influence the rheological property and rutting resistance. The slow curing speed of the PU binder decreased the dynamic modulus and rutting resistance but did not influence the phase angle. The rise in PU binder content would only improve the PU mixture’s resistance to rutting. The curing condition and color additive had no impact on the PU mixture’s properties. The generalized logistic sigmoidal (GLS) and Christensen Anderson and Marasteanu model (CAM) models could precisely predict the dynamic modulus and phase angle respectively disregarding the PU mixture features. PUM-10/B exhibited the greatest rutting resistance. The findings will aid in comprehending the properties and influencing factors of the PU mixture as well as in designing the desired mixture.