Polyurethane Component Research Articles

Integrating CLSP and GLSP models for optimizing production batch sizes in vulcanized component manufacturing

This study addresses the complex issue of optimizing production batch sizes within a company specializing in manufacturing rubber, thermoplastic, and polyurethane components, all of which undergo vulcanization prior to sale. Through meticulous analysis of the production planning process, it was observed that certain activities could be logically grouped into two sequential stages without compromising information integrity or detail. The initial stage encompasses press activities involving vulcanization and curing, while the next one involves greenhouse operations for post-curing. The commencement of the second stage is contingent upon the completion of all activities in the first stage. Consequently, an effective production plan must concurrently consider both stages. To tackle this, a mathematical model is proposed to address the batch sizing problem within the company, integrating both stages and drawing inspiration from the CLSP (Capacitated Lot Sizing Problem) for the first stage and the subperiod approach derived from GLSP (General Lot-sizing and Scheduling Problem) models for the second stage. The model is solved utilizing the CPLEX solver version 12.8. It incorporates 74 items, spans 20 periods, each with specific demands, and delineates 16 sub-periods within each planning horizon period. Experimentation involving a hypothetical example and subsequent tests utilizing real data from the case study company demonstrate the successful resolution of the problem, yielding enhanced production plans, particularly in terms of cost reduction objectives.

Feasibility and environmental assessment of introducing waste polyurethane from wind turbine blades as a modifier for asphalt

Recycled glass fibers from wind turbine blades have significant potential for enhancing the performance of asphalt mixtures. However, the impact of residual polyurethane (PU) components on asphalt performance remains uncertain, presenting a challenge to the high-value utilization of wind turbine blades in pavement engineering. This study investigates the effects of waste polyurethane (WPU) on the rheological properties and compatibility of SBS modified asphalt, widely used in pavement engineering under various temperature conditions. Molecular dynamics (MD) simulations were employed to analyze the underlying mechanisms. The results reveal that incorporating WPU improves the rutting factor and creep recovery rate of SBS modified asphalt, demonstrating superior high-temperature performance compared to SBS modified asphalt alone. The synergistic effect of WPU and SBS significantly enhances low-temperature crack resistance and overall asphalt compatibility. Additionally, the interaction between SBS and the four components of asphalt is strengthened, and diffusion mobility is reduced due to WPU incorporation. This indicates that WPU promotes a more compact structure and a higher relative concentration of SBS and the four components within the spatial system, thereby enhancing the stability of the WPU/SBS modified asphalt system. Furthermore, using WPU in asphalt mixtures not only avoids environmental pollution compared to traditional disposal methods but also offers considerable long-term economic benefits. Overall, WPU positively impacts the rheological properties and compatibility of SBS-modified asphalt, suggesting that processed wind turbine blades can be a viable solution for enhancing asphalt mixture performance.

A Numerical Analysis Model of Composite Pneumatic Formwork Considering the Stiffness Contribution of Polyurethane Layer

Pneumatic formwork is a kind of inflated fabric-polyurethane composite formwork formed by spraying polyurethane on the interior surface of the membrane. A numerical analysis model of composite pneumatic formwork considering the stiffness contribution of polyurethane is proposed to predict the structural response. The analysis model simulates the component of fabric and polyurethane with membrane elements and shell elements respectively, and Tie constraint of surface to surface is defined at the interface. A nonlinear material model for fabric is adopted considering the influence of stress ratio and loading history, and the constitutive relation of polyurethane is described in the foaming plane with different properties for tension and compression. Newton-Raphson incremental iterative method is used to solve the involved nonlinear problems. The simulation accuracy of the proposed analysis model is verified by comparing its predictions with test results about the loaddeformation response of an inflated membrane structure and the corresponding composite pneumatic formwork under horizontal loading. The numerical model is further used to investigate the influence of the thickness of polyurethane layer on the improvement of overall structural stiffness of a larger pneumatic formwork under horizontal fresh gale, and the polyurethane is proved to be beneficial for the shape-control of pneumatic formwork.

Experimental Study on Mechanical Properties of Polyurethane Cement Composite (PUC) Under Various Temperatures

This paper aims to investigate the mechanical properties of polyurethane cement (different ratios) at different ambient temperatures. The temperature and proportion which affect the constitutive relation of the material were analyzed by axial tensile test. The microstructure and failure mode of polyurethane cement were studied using scanning electron microscope technology. At -40oC ~40oC, the stress-strain curves of polyurethane cement with different proportions were roughly similar. When the temperature was higher than 40oC, with the rise of temperature, the ultimate tensile strength of polyurethane cement specimens would decrease but the ultimate strain would increase. When the temperature was lower than -40oC, with the decline of temperature, the ultimate strain and tensile strength of polyurethane cement specimens would decrease. The ultimate stress of polyurethane cement with different ratios was different. With the rise of the proportion of polyurethane components, the ultimate stress would increase but the elastic modulus would decrease. Macroscopically, the failure modes of polyurethane specimens were different with the change of temperature. Brittle fracture occurred at low temperatures. At high temperatures, the specimen did not fracture, but a large number of �V�shaped cracks appeared at the edge. The higher the temperature, the more obvious this phenomenon was. At the microscopic level, the fibers didn t break at high temperatures, and there were obvious cracks and more stubble on the surface of cracks at room temperature.

High adhesive and mechanically stable SR/PU IPNs coating with dual-functional antifouling/anticorrosive performances

Silicone rubber (SR) based coatings with remarkable antifouling performances have received tremendous interests due to their prominent merits of environmental adaptability, stability, non-toxicity. However, it still remains a great challenge to fabricate SR-based antifouling coatings with both high mechanical properties for the bulk coating and high adhesion properties to substrates. Herein, a dual-functional SR-based coating with both antifouling and anticorrosive performances was developed by incorporating polyurethane (PU) chains into the SR framework to form SR/PU interpenetrating polymer networks (SR/PU IPNs), to maintain its high adhesion to metal substrate without compromising surface antifouling properties. By adjusting the mass ratio of SR and PU components, the adhesion of the SR/PU IPNs to the substrate as well as its mechanical properties can be remarkably improved. Compared with the pristine SR, the SR/PU75 IPNs possessed the optimized mechanical properties, with the increases in the Young's modulus and compression modulus, by ~312 % and ~289 % respectively. Additionally, the adhesion strength of the composite was increased by 369 %. Owing to the synergistic effect of SR/PU IPNs, the SR/PU75 IPNs realized synchronous enhancement of antifouling and anticorrosion performance. After 28-day immersion in 3.5 % NaCl solution, the SR/PU75 IPNs coating was tightly bonded with the substrate, and exhibited a maximum |Z|0.01Hz value of 1.254 × 108 Ω·cm2.This proposed dual-functional SR/PU IPNs coating may provide a novel strategy for the future development of marine instruments and equipment, where both strong mechanical performances and high antifouling/anticorrosion performances are acquired.

Linear viscoelastic shear and bulk relaxation moduli in poly(tetramethylene oxide) (PTMO) using united-atom molecular dynamics

A quantitative understanding and prediction of the viscoelastic relaxation behavior of polymer melts is required to build up predictive multiscale models, which can be utilized for the practical design of viscoelastic materials. We report the application of the Green–Kubo method to compute the common shear relaxation modulus and the rarely reported bulk relaxation modulus for a realistic united atom model of poly(tetramethylene oxide) (PTMO), which is one key components of the segmented polyurethane (PU) elastomers. The temperature and molecular weight dependent viscoelastic behavior is investigated in detail by computing the bulk relaxation modulus K(t) along with shear relaxation modulus G(t). Our results provide new rheological data for PTMO melt based on the united atom model, which incorporates the chemical details of the polymer backbone. The predicted stress relaxation are mapped onto master curves using the time–temperature superposition principle with horizontal and vertical shift factors. The computed shift factors agree with the Williams–Landel–Ferry equation and appear to be similar for the shear and bulk relaxation modulus. The underlying dynamics for the shear and bulk relaxation modulus appear to stem from the same mechanistic origin as both processes seem to sample similar kinetic signature of the reference time scale of the underlying thermally activated processes in the liquid. Our results demonstrate furthermore, that MD simulations with the chemical details beyond coarse-grained models can sample the Rouse dynamics and the transitions towards entanglement, which is evident by the emergence of a plateau in shear relaxation modulus and scaling relations in the diffusion behavior of the monomer at larger molecular weights.

Synthetic polyurethane nanofibrous membrane with sustained rechargeability for integrated air cleaning

Health problems caused by airborne particulate matter (PM) and bacteria have placed a severe burden on public health. At present, most personal protective equipment focused on PM filtration but ignored the threat from pathogens like bacteria in the air. Moreover, the disposable protective items such as masks used in large quantities have caused great pollution issues. Hence, in this study, a fresh polyurethane nanofibrous membrane (named as PU/PIU-Cl) was synthesized with imidazolidinyl urea groups as block components for enhanced biocidal effect which not only has extremely high filtration efficiency (up to 99.92%) against particulate pollutants, but also excellent intrinsic antibacterial ability (>99%) and safety, indicating its remarkable performance for integrated air pollution control. Furthermore, the antibacterial ability of the membrane can be facilely regenerated by re-chlorination, and the active chlorine content of PU/PIU-Cl membrane through halogenation hardly decreased after five cycles. Therefore, the PU/PIU-Cl nanofibrous membrane can not only be used as protective equipment, such as masks with sterilization function, but also can effectively alleviate the pollution problem of disposable protective products. • Imidazolidinyl urea groups are employed as block components of polyurethane. • PU/PIU-Cl exhibits intrinsic antibacterial function and high filtration efficiency. • PU/PIU-Cl is low cytotoxic, low cost and reusable, and shows great potential in PPE.

Water transport in epoxy/polyurethane interpenetrating networks

AbstractDiffusion of water in epoxy–polyurethane (PU) interpenetrating networks was investigated using gravimetry, time‐resolved ATR‐FTIR, and 2D correlation analysis. In this study, the amount of PU component and the length of polyethylene oxide soft block in them were systematically varied to determine their influence on water uptake. The diffusion coefficients were calculated and anomalous water diffusion is well described by the Carter and Kibler model. Water molecules of four different states were identified in the network volume, and sequence of their formation was determined by 2D‐IR spectroscopy. One of them could be confined into free volume (microvoids) or molecularly dispersed with hydrogen‐bonding at cluster formation (bulk dissolved), while the others could be attributed to the bound water forming strong hydrogen bonds with hydrophilic entities of networks. These results were supported by solid‐state 2H NMR data. The influence of water uptake on thermomechanical behavior of epoxy/PU networks was determined. It was shown that the increase of PU content in composites leads to the changes of the effect of water uptake from plasticizing to the anti‐plasticizing as a result of the formation of new networks of interchain hydrogen bonds.

Effect of reaction time on the molecular weight distribution of polyurethane modified epoxy and its properties

This paper studied the synthesis of polyurethane modified epoxy via simultaneous reaction by varying the reaction time to 30, 60, and 90 min. The polypropylene glycol and tolonate as polyurethane components were reacted simultaneously with epoxy in the presence of catalyst dibutyltin dilaurate without prepolymer polyurethane first. The effect of various reaction times on polyurethane modified epoxy (PME) properties was studied by analyzing molecular weight distribution, viscosity, epoxy equivalent weight, pot life, dry-to-touch time, elongation at break, tensile strength, and compared to the unmodified epoxy. The various reaction time processes of polyurethane-modified epoxy tend to increase the molecular weight and influence the molecular weight distribution of PME. It indicated that the reactivity polymerization of epoxy resin with polyurethane component increased with reaction time. Furthermore, these properties affect other properties, i.e., viscosity, epoxy equivalent weight, pot life, and tensile strength increase.

Fabrication and characterization of shape memory auxetic metamaterial

The process of repeating shape memory cycle of the shape memory foam whose initial structure is nonauxetic is more complex. In this cases, only one-shot deformation, which will greatly limit the application of this smart metamaterial. Thus, in this study, we report a feasible approach of fabricating the original structure of shape memory foams with auxetic property based on second curing method. The commercial soft polyurethane foam material and shape memory epoxy resin was used in fabricating the shape memory auxetic foam. Polyurethane component plays role in the similar function of “auxetic mold,” while shape memory polymer act as fixing auxetic structure of foam. The negative Poisson’s ratio was achieved around −0.22. Tunable foam mechanical property was demonstrated by structural control according to its shape memory property. The functional filler was employed to realize the wireless actuation of auxetic foam. The excellent shape memory properties have been achieved as well. The combination of smart materials and metamaterial structure makes it have excellent structural mechanical properties and intelligent properties of materials, which greatly expands their potential application prospects.

Predictive Maintenance and Engineered Processes in Mechatronic Industry: An Italian Case Study

The paper proposes the results of a research industry project concerning predictive maintenance process optimization, applied to a machine cutting polyurethane. A company producing cutting machines, has been provided with an online control system able to detect blade status of a machine supplied to a customer producing polyurethane components. A software platform has been developed for the real time monitoring of the blade status and for the prediction of the break up conditions adopting a multi-parametric data analysis approach, based on the simultaneous use of unsupervised and supervised machine learning algorithms. Specifically, the proposed method adopts a k-Means algorithm to classify bidimensional risk maps, and a Long Short Term Memory (LSTM) one to predict the alerting levels based on the analysis of the last values for some process variables. The analysed algorithms are applied to an experimental dataset.

Allergic contact dermatitis caused by polyurethane components in bulletproof glass manufacturing.

Allergic contact dermatitis caused by polyurethane components in bulletproof glass manufacturing.

Determination of Strain Limits for Dimensioning Polyurethane Components.

Within the scope of this contribution, a method for the determination of a strain limit for designing components made of elastomeric polyurethane systems is presented. The knowledge of a material-specific strain limit is essential for the structural-mechanical calculation of plastic components in the context of component design. Compared to a commonly used component design, based on a simplified dimensioning approach taking only linear viscoelastic deformations into account, the strain limit determined in this study allows an improved utilisation of lightweight construction potential in the dimensioning of technical components made of polyurethanes through the consideration of permissible nonlinear viscoelastic deformations. The test method comprises a sequence of quasi-static loading and unloading cycles, with a subsequent load-free recovery phase, allowing the relaxation of the viscoelastic forces. Standardised tensile and simple shear test specimens and a dynamic mechanical thermal analyser (DMTA) are used within the tests. The strain limit is determined by means of the so-called residual energy ratio, which is a characteristic quantity for the evaluation of hystereses of load–unload cycles. These hystereses are increasingly formed by deformations outside the range of linear viscoelastic deformations. The residual energy ratio relates the proportion of deformation energy recovered during unloading to the deformation work that is applied. In this contribution, the residual energy ratio is successfully used to detect a significant evolution of loss energy under increasing load and to correlate this transition to a characteristic strain. The latter is used as a dimensioning parameter for the design of components made of elastomeric polyurethane materials for quasi-static load cases. The determination of this strain limit is performed under consideration of the criterion of reversibility of deformation.

Investigating the mechanical performance of advanced marine coatings used for bonding composites to aluminum in-mold

ABSTRACT Advanced Marine Coatings (AMCs) are a combination of polyurethane technology with polyester technology. In this study, AMCs’ various formulations were tested for mechanical properties and lap shear strength between composite laminates and aluminum. Castings were fabricated for each formulation, and their mechanical properties were obtained through ASTM Testing. The lap shear strength between composite laminates and aluminum was determined by single lap shear testing. Numerical models were created to simulate the experimental lap joint testing and further analyze the adhesive at the joint using the mechanical properties obtained in this study. The numerical model was used to produce peel strain and shear strain contour plots of the adhesive and peel stress and shear stress distributions at the mid-layer of the adhesive at 85% failure load. The effects of changing the ratio of the polyurethane components on the AMC’s performance were also investigated. With the exception of failure shear strain, the mechanical properties were found to be inversely proportional to the amount of polyurethane added to the formulation. However, increasing the ratio of isocyanate to polyol increased the formulation’s mechanical properties at each formulation’s specified polyurethane percentage.

A feasibility study on production and optimization of PVDF/PU polyblend nanofiber layers using expert design analysis

Different polymer blends are electrospun to produce nanofibers with novel combined features. In this study, the feasibility of combining polyurethane (PU) and polyvinilidine floride (PVDF) polymer was evaluated to produce an adequate nanoscale layer. This scale would increase the β-phase in PVDF; the lowest beads in the nanolayers, to achieve a smooth layer with more uniform strength. To manufacture PVDF/PU, the PVDF was combined with PU components for elastic behavior. Eighteen experimental design points were performed using Design-Expert software, based on electrospinning variables, including solution concentration, applied voltage, and the needle to collector distance. SEM study was carried out to assess the fiber diameter and the bead numbers to characterize the surface morphology of nanofibers. Chemical reactions between the two polymer components and the fibers inner structure were investigated through FTIR and XRD. According to the experiment design, 14% (wt) solution concentration, 18 kV voltage, and 24 cm distance between the needle tip and the collector were considered as the optimum conditions during electrospinning. FTIR test revealed that there was no chemical reaction between the TPU and PVDF components. Also, several β-phases were formed during the electrostatic drafting of a polyblend solution. Moreover, the XRD results showed that the PVDF/TPU composite had low crystallinity compared to pure TPU and PVDF. Finally, it was concluded that providing uniform nanofiber mats by applying the optimum condition during electrospinning would result in PVDF/TPU polyblend higher piezoelectric features nanofibers.

Investigation on performances and nano-adhesion behavior of ultra-thin wearing course using polyurethane as binder

An ultra-thin wearing course is a promising maintenance method for prolonging the service life of the pavement. This study used polyurethane (PU) as a binder to develop an ultra-thin wearing course with high skid and wear resistance (named as PUTWC). The performance and nano-adhesion behavior of PUTWC were investigated by experimental and molecular dynamics (MD) simulation methods. The relationship between the mechanical properties of aggregates and the skid resistance of PUTWC was further analyzed using the grey correlation method. Results indicated that PUTWC using the emery with a particle size of 2–3 mm as the aggregate expressed a more favorable wear and skid resistance, also higher structural stability. The impact and polishing value of aggregates showed a more significant effect on the wear resistance of PUTWC. The adhesive bonding property between the PU and aggregates was investigated using the MD simulation by comparing the interfacial interaction energy, fraction of free volume, and relative concentration distribution of the PU component. Results showed that a stronger adhesion existed between the PU and emery compared with the ceramic particles, which was consistent with the performance test results. The conclusions of MD simulation were confirmed by the test results of scanning electron microscopy (SEM) and positron annihilation lifetime spectroscopy (PALS).

Monitoring Polymer Diffusion in a Waterborne 2K Polyurethane Formulation Based on an Acrylic Polyol Latex

We report experiments based upon fluorescence resonance energy transfer (FRET) measurements designed to examine mixing at the molecular level of the components of a waterborne 2K polyurethane (WB2KPU) formulation. The system consists of an acrylic polyol latex (Mₙ = 4200 g/mol, D = 2, Tg ≈ 15 °C) with a uniform hydrodynamic diameter (dₕ) ≈ 120 nm plus a water-dispersible polyisocyanate (hmPIC, Basonat HW1000 from BASF). We prepared components labeled with phenanthrene (Phen) as the donor dye or with a dimethylaminobenzophenone (Nben) as the acceptor dye. Dynamic light scattering was used to monitor the size and size distribution of the components in the dispersed phase in solution. This signal was dominated by the polyol nanoparticles, which were much larger than the tiny droplets formed by the hmPIC in water. Experiments were carried out at a mole ratio of NCO/polyol-OH of 1.3. We found that the particle size and narrow size distribution remained unchanged up to 22 h after mixing the polyol with the PIC. FRET experiments were carried out on samples in the dispersed state as well as on films formed from these dispersions. Films formed from a 1:1 mixture of (polyol-Phen + polyol-Nben) showed relatively little energy transfer (ΦET = 0.19) even after several hours aging at ambient temperature, indicating that little polymer diffusion occurred in these low-molecular-weight latex films. In contrast, films formed from mixtures of (polyol-Phen + polyol-Nben + hmPIC) showed more extensive energy transfer (ET) (ΦET = 0.51), indicating essentially complete mixing at the molecular level of the polymer molecules in the presence of hmPIC. The key conclusion is that hmPIC is a reactive plasticizer that promotes diffusion in this system on a much faster scale than the cross-linking reaction. This result is confirmed by experiments that examined mixtures of (hmPIC-Phen + polyol-Nben), which also showed essentially molecular scale mixing between these two different components. In this later system, aging at room temperature led to a small decrease in ΦET over time that was more prominent for films aged at high humidity (75%) than at lower humidity (45%). This result suggests that hydrolysis of NCO groups in the film, leading to polyurea formation, promotes local phase separation accompanied by a net increase in the average separation of Phen and Nben groups in the film.

Kinetics of formation and viscoelastic and mechanical properties of optically transparent interpenetrating networks of poly(methyl methacrylate)/polyurethane

An optically transparent material with enhanced physical-mechanical properties was synthesized, which is based on the in situ formed sequential interpenetrating polymer networks of poly(methyl methacrylate)/polyurethane with an oligoester component. The kinetic features of polymerization of methyl methacrylate in these systems were studied. It was established that the polymerization rate of methyl methacrylate increases with an increase in the content of a polyurethane component, which results from an increase in the system viscosity. Irrespective of the content of polyurethane (15, 20 or 25 wt.%), optically transparent materials with a light transmission coefficient of about 90% were formed. The method of dynamic mechanical analysis showed that the modification of cross-linked poly(methyl methacrylate) with cross-linked polyurethane led to a decrease in the value of the elastic modulus; the value of the loss modulus being increased with an increase in polyurethane content. This indicated bot a decrease in fragility and the improvement in impact strength of the glass-like material. According to the study of physical-mechanical properties of the materials, the presence of polyurethane in their composition resulted in an increase in the impact strength and relative breaking elongation and in the reduction of the Young modulus. It was found that the interpenetrating polymer network containing 20% of polyurethane showed the best values of breaking strength, breaking elongation and Charpy impact.

Improving revenue from lignocellulosic biofuels: An integrated strategy for coproducing liquid transportation fuels and high value-added chemicals

In conventional biomass-to-biofuel production processes, cellulose and hemicellulose are converted only to biofuels. However, to improve the economics of the process, it is desirable that some fractions of biomass be produced as fuels and other fractions as chemicals. This coproduction of fuels and chemicals also enables a flexible response to the market conditions of bioproducts, rather than producing only biofuels or biochemicals. Moreover, the use of all fractions, not only cellulose and hemicellulose but also lignin, improves the economics of the process. We propose a biorefinery strategy for the coproduction of liquid hydrocarbon fuels and chemicals from lignocellulosic biomass. In this study, all three primary components of biomass were converted into high-value products that can be commercialized: (1) cellulose, which is converted into butene oligomers (BO) for transportation fuels, (2) hemicellulose, which is converted into 1,5-pentanediol (1,5-PDO) that can be used as polyester and polyurethane components, and (3) lignin, which is converted into carbon products, such as carbon fibers or battery anodes. By maximizing the biomass utilization up to 47.8% from biomass to valuable products, the economic viability of the proposed process can be increased. Technoeconomic analysis shows that the minimum selling price of BO is $4.21 per gallon of gasoline equivalent in the integrated strategy, indicating that it is a promising alternative to current biofuel production approaches.

Simple process for separation and recycling of nylon 6 and polyurethane components from waste nylon 6/polyurethane debris

The nylon 6 (PA6)/polyurethane (PU) debris produced during the sanding process would result in a serious resource waste and environmental hazard if disposed of inappropriately. Therefore, this study proposed a simple process for separating and recycling PA6 and PU components of PA6/PU debris. Results revealed that the instantaneous dissolution of PU in N,N-dimethylformamide was independent of temperature and time but related to the quantity of the solvent. Further investigation showed that 43.2% of waste PA6/PU debris was dissolved at room temperature, with pulp density of 10% and within 10 minutes, indicating that PA6 and PU could be quickly separated from the waste PA6/PU debris. In addition, proton nuclear magnetic resonance indicated that the dissolved PU could be recovered by selective precipitation-stripping using an equal amount of deionized water. Moreover, the chemical structure analysis disclosed that the PU in PA6/PU debris should be polyether PU synthesized by reacting with methylene diphenyl diisocyanate and polyether polyols. Besides, the stable chemical structure and thermal properties of separated samples observed from differential scanning calorimetry and thermogravimetry results confirmed that the recycling products could be reused as recycled plastic materials.