Types Of Polyurethanes Research Articles

Rhodamine B dye staining for visualizing microplastics in laboratory-based studies.

In the recent years, microplastics have attracted much attention as new emerging environmental pollutants. Previously, several studies were performed to understand the source and fate of microplastics in the environment, organisms, and food webs. To track microplastics and improve their legibility, labeling them is a very effective method during laboratory experiments. This study presents an effective Rhodamine B dye (RhB) staining method for microplastics. The method is crucial for the visual observation of white or transparent plastics by dyeing them in purple or pink, as well as makes the microplastics to fluoresce under common microscope fluorescence filter ranges. Five types of microplastic polymers, namely polyethylene, polypropylene, polystyrene, polyvinyl chloride, and polyurethane were used as the test materials. The efficiencies of ethanol, acetone, and distilled water as possible solvents for dissolving RhB were investigated. Next, the fluorescence stability in various conditions was assessed. The results indicated that ethanol was the most appropriate solvent in dissolving RhB used in staining the microplastics. RhB was fluorescently stable under varying conditions (light and gut fluid) or different solutions (KOH, nitric acid, and saturated NaCl). Additionally, RhB staining exhibited an insignificant effect on the Raman spectra of the microplastics. Our proposed method is simple and robust and helps to visualize the different types of microplastic polymers tested in laboratory experiments, particularly the transparent, white, and small size microplastics.

Synthesis and characterization of paraffin wax nanocapsules with polyurethane shell (PU/PW); the droplet size distribution: A key factor for thermal performance

The impact of this research is to present results obtained from synthesis of nanoencapsulated Paraffin wax core/Thermoplastic elastomer Polyurethane shell with various particle size distribution via mini-emulsion polymerization that could be utilized in thermal energy storage. To achieve this objective, five different types of Polyurethane shell/Paraffin wax core nanocapsules have been synthesized based on Polyethylene glycol and Isophorone diisocyanate with Polycaprolactone assistance to improve fusion enthalpy and thermal performance. Process conditions including ultrasonic time and reaction temperature have been assigned differently to study effect of reaction parameters on PU/PW particle size distribution and time-temperature performance. Findings have shown that, increasing sonication time from 15 to 20 min and reaction temperature from 60 to 80 °C, mini-emulsion core droplet size has been decreased and narrow size distribution has been attained. Furthermore, molecular and morphology analysis and phase change thermal investigations confirmed polyurethane shell formation around spherical paraffin wax core. Moreover, thermal cycling test has been indicated high thermal performance and improved resistance of prepared core/shell, even after 100 heating/cooling cycles and approved its great potential for thermal energy storage applications. To conclude, narrow size distributed paraffin wax nanocapsules demonstrated effective and superior time-temperature history in contrast with broad size distributed nanocapsule.

Self-Healing Polyurethane-Based Nanocomposites Modified with Carbon Fibres and Carbon Nanotubes

Self-healing polyurethanes (PUs) were synthesized as a matrix of nanocomposites containing two fibrous carbon components, i.e., functionalized carbon nanotubes (CNF-OH) and short carbon fibers (CF). Two types of PUs differing in the content of flexible chain segments (40% and 50%) were used. Changes in mechanical strength were analyzed to assess the ability to self-healing of PU-based matrix nanocomposites with experimentally introduced damage in the form of an incision. The healing process was activated by heating the damaged samples at 60°C, for 30 minutes. The addition of CNT-OH and CF caused a slight reduction in the self-healing ability of the nanocomposites as compared to the neat PUs. After heating to 60°C, the nanocomposites self-healed up to 72% of the initial strength of the undamaged samples. The introduction of fibrous components to the polymer matrix improved the thermal conductivity of nanocomposites and facilitated heat transfer from the environment to the interior of the samples, necessary to initiate self-healing. Low content of carbon components in the PU matrix, i.e., 3 wt% of CF and 2 wt% of CNF-OH increased the total work up to fracture of samples after healing by about 53%.

Properties of sugarcane fiber/polyurethane‐crosslinked epoxy composites under different interfacial treatments

AbstractThe effect of the ultrasonic/mechanical stirring method (physical treatment) and 3‐glycidoxypropyltrimethoxy silane (GPS, chemical treatment) modifications on the sugarcane fiber (SGF)/epoxy composites was investigated to improve the interfacial interaction between fiber and epoxy resin. An optimum concentration GPS at 2 wt% was found for the best improvement in tensile strength at 40 wt% SGF content based on the evaluation of GPS content, indicating the role of GPS as an effective coupling agent. Overall, the best improvement in tensile strength was observed for GPS‐modified cases, and particularly tensile strength reached up to 32.9 MPa at 50 wt% of fiber content. In addition, three types of Polyurethane (PU)‐modified epoxy with different polyols at various SGFs contents were investigated. In all cases, the tensile strength of SGF/PU‐epoxy cases was higher than that of SGF/epoxy cases due to the relatively lower viscosity of PU‐epoxy to easily wet the SGF surface. In general, impact strength for samples without physical or chemical treatment also ranked the lowest value in most cases. The enhanced interfacial interaction between SGF and epoxy for surface‐modified cases was suggested through the morphology observation, dynamical mechanical analysis, and the onset degradation improvement in thermal stability.

Use of peanut shell-based polyurethane type rigid foam in removing remazol orange RGB dye from aqueous solution

This study reflects the adsorption ability and usable of peanut shell-polyurethane type rigid foam for the removal of remazol orange RGB (RO-RGB) dye, a reactive dye, from aqueous solution. RO-RGB removal was studied for initial dye concentrations (10-150 mg l-1), pH values (3-9), and temperatures (20-60C) at various contact times. Dye removal increased with the increases in initial dye concentration and temperature while it was decreasing with an increase in pH. Maximum dye removal was determined to be about 98% under all the experimental conditions. Equilibrium data obtained were adapted to the Langmuir, Freundlich, and Temkin isotherm models, and it was seen that the adsorption obeyed the Freundlich isotherm model with determination of coefficient of r2 = 0.966. Kinetics data was found to be harmony with the pseudo-second kinetic order model (higher than r2 = 0.9908). As a result, it was determined that the polyurethane-type rigid foam produced from peanut shell could be used as an alternative to activated carbon and could easily be used as an adsorptive material to remove RO-RGB dye.

Application of Walnut Shells-Derived Biopolyol in the Synthesis of Rigid Polyurethane Foams.

This study aimed to examine rigid polyurethane (PUR) foam properties that were synthesized from walnut shells (WS)-based polyol. The Fourier Transform Infrared Spectroscopy (FTIR) results revealed that the liquefaction of walnut shells was successfully performed. The three types of polyurethane (PUR) foams were synthesized by replacement of 10, 20, and 30 wt% of a petrochemical polyol with WS-based polyol. The impact of WS-based polyol on the cellular morphology, mechanical, thermal, and insulating characteristics of PUR foams was examined. The produced PUR foams had apparent densities from 37 to 39 kg m−3, depending on the weight ratio of WS-based polyol. PUR foams that were obtained from WS-based polyol exhibited improved mechanical characteristics when compared with PUR foams that were derived from the petrochemical polyol. PUR foams produced from WS-based polyol showed compressive strength from 255 to 310 kPa, flexural strength from 420 to 458 kPa, and impact strength from 340 to 368 kPa. The foams that were produced from WS-based polyol exhibited less uniform cell structure than foams derived from the petrochemical polyol. The thermal conductivity of the PUR foams ranged between 0.026 and 0.032 W m−1K−1, depending on the concentration of WS-based polyol. The addition of WS-based polyol had no significant influence on the thermal degradation characteristics of PUR foams. The maximum temperature of thermal decomposition was observed for PUR foams with the highest loading of WS-based polyol.

Influence of Rubber Particle Size on Functional Properties of a Composite Material Based on Scrap Tires and a Polymer Binder

Functional properties of composite material based on mechanically grinded scrap tires with different particle size of fractioned crumb and polyurethane type polymer binder were investigated to estimate influence of rubber particles size and content on composite material properties (Shore C hardness, compressive stress at 10 % deformation, tensile strength, elastic modulus and elongation at break, apparent density). Optimization possibilities of composite material consisting of rubber particles with different sizes or fractions were investigated. The obtained results show that variation of composition of the composite material by changing size of rubber granulate have definite influence on selected properties of the material. Purposeful selection and mutual combination of rubber particles size included in material can ensure desirable and predictable mechanical properties of composite material.

Architectural Sustainability and Efficiency of Enhanced Waterproof Coating from Utilization of Waterborne Poly (Siloxane-Imide-Urethane) Copolymers on Roof Surfaces

According to Taiwan’s Ministry of the Interior, from 2017 to 2019, more than 12% of house-purchase disputes were due to water leakage caused by frequent tropical rains, which have long troubled engineers. The thermal stability resistance, water resistance, and ultraviolet resistance of existing polyurethane formulations have been limited by environmental aging. Thus, the lifespan of commercial PU-coated resins (typical PU) for the waterproofing of roof surfaces is merely two to three years. Accordingly, this study proposed the introduction of siloxane and imide groups to produce waterborne poly(urethane-siloxane-imide) (Si-imide-WPU) copolymers to improve the resistance of environmental aging in typical PU. The waterproof coating resin made of Si-imide-WPU copolymers was environmentally friendly, safe to use, and free of organic solvents. The results showed that the optimal Si-imide-WPU-2 sample in the study made improvements on the defects of polyurethane (PU) including its thermal properties, mechanical properties, environmental resistance, and lifespan which could be extended up to 5.4 years. Consequently, the studied Si-imide-WPU copolymers could reduce material waste while enhancing the sustainability and efficiency of the architecture.

Polyurethane covalently modified polydimethylsiloxane (PDMS) coating with increased surface energy and re-coatability

In the present study, with 2-Allyloxyethanol-terminated polyurethane (AEPU) and allyloxy (polyethylenene oxide) methyl ether-graft-polymethylhydrosiloxane (PMHS-g-AEM) as modifier and reactive compatibilizer respectively, a type of polyurethane modified polydimethylsiloxane (PUMS) coating with increased surface energy and re-coatability was obtained via solvent-free two-component hydrosilylation reaction. The structures of as-prepared AEPU and PMHS-g-AEM were characterized by FTIR and 1H NMR, and the AEPU distribution in PUMS together with the characteristics of resultant coatings, such as dynamic wetting properties, surface roughness, surface energy and re-coatability, variation in curing behavior and mechanical properties were also elaborately evaluated. From scanning electron microscope (SEM) observation, it is found that in presence of 2 wt% compatibilizer, AEPU can be distributed in PUMS uniformly. With the increase of AEPU loading, the coating surfaces show a decreased water contact angles (WCAs), increased surface roughness and enhanced surface tension from 29.4–52 mN/m as well as re-coatable feasibility. Intriguingly, curing kinetics study reveals that the conjugation of 10 wt% AEPU into two-component hydrosilylation system can significantly reduce the reaction activation energy by 43.6 %. Another interesting result is that the chemical incorporation of AEPU dramatically improves elongation at break of PUMS film from 460 to 808 % while well-maintains tensile strength. All aforementioned results distinctly demonstrate a feasible yet promising paradigm for modifying PDMS coating with polyurethane.

Four-dimensional printing of shape memory polyurethanes with high strength and recyclability based on Diels-Alder chemistry

A type of polyurethane with high mechanical performance, excellent recycling ability and shape memory property based on Diels-Alder (DA) reactions has been fabricated through digital light processing (DLP) 3D printing. Firstly, polyurethane acrylate with DA-adduct is synthesized, and then compounded with reactive diluent and photoinitiators to get a series of photopolymer resins. Benefiting from the high curing rate and good fluidity, one type of photopolymer is applied in DLP 3D printing. The excellent mechanical and recycling properties of the cured polymers are proved through tensile tests. The printed samples exhibit remarkable shape memory performance with the shape fixity and recovery ratios of 96.4 ± 0.1% and 99.3 ± 0.3%, respectively and high shape recovery stress of 10.1 MPa, which is very high for shape memory polymers.

Room‐Temperature Self‐Healing and Reprocessable Waterborne Polyurethane with Dynamically Exchangeable Disulfide Bonds

AbstractRecently, covalent adaptable networks (CANs) based on dynamic exchange reactions have been synthesized, and the research on these materials has been mainly focused on the self‐healing behavior and reprocessing properties of CANs. Disulfide bonds can be considered to be a type of dynamic reversible covalent bonds, and exchange reactions of disulfide bonds proceed easily at mild temperatures, which endow materials containing disulfide bonds with self‐healing properties and the reprocessability under suitable conditions. Herein, we synthesized a type of waterborne polyurethane (WPU) CAN incorporated with disulfide bonds. A reasonable structural design was used in conjunction with a self‐healing kinetic analysis to predict that the highest performing CWPU‐8 sample could repair a microcrack at room temperature, which was verified by optical microscopy observations combined with self‐healing mechanics. The most important feature of this material is its reprocessing property, which was investigated by rheology tests. These assessments demonstrate that the self‐healing behavior and the reprocessability are closely related to exchange reactions of disulfide bonds, and the structure‐property relationship provides deep insights into the CANs chemistry.

Improving the consolidation properties of hydrophilic polyurethane for feldspathic sandstone water erosion prevention.

Feldspathic sandstone is a type of sandstone that is severely eroded by wind, rainfall, and gravity forces. The land surface in feldspathic area is degraded and covered with extremely low vegetation coverage. In this study, we propose a type of hydrophilic polyurethane (W-OH) to control its erosion and conduct the experiment to evaluate the consolidation performances. The results showed that the cementing materials (such as montmorillonite) are the main reason for the vulnerability of feldspathic sandstone to erosion, which expands by absorbing water. Additionally, the organic content is extremely low and is not suitable for vegetation growth. However, when the different concentrations of W-OH solution were sprayed on the feldspathic sandstone surface, the solution could penetrate in several minutes and form a flexible and porous consolidation layer. The anti-scourability index (K) of the layer could increase from approximately 0.2 to 1.0 which significantly increased the water resistance. The water retention benefit increased by 50%. In the simulated rainfall test, the sediment yield reduction in the treated slopes sprayed with the W-OH solution could reach 99% compared with that on the control slopes. The SEM images indicated that the W-OH solution enveloped the feldspathic sandstone particles and connected them tightly together. Therefore, the consolidation layer could decrease water erosion rate and reduce evaporation.

Super protective anti-bacterial coating development with silica-titania nano core-shells.

In the present study, we have developed an anti-bacterial as well as mechanically-strengthened super protective coating material, which can be used as a marine antifouling paint. In this research, silica, titania and silica–titania core–shell nanoparticles were individually prepared via sol–gel and peptization processes. The idea behind the synthesis of core–shell nanoparticles was to utilize the mechanical strength of silica and the antimicrobial property of TiO2 together. These nanoparticles were characterized via dynamic light scattering, UV-Visible spectroscopy, X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. Coating formulations were developed with two types of model binders, i.e., solvent-based polyurethane and water-based poly-acrylic, containing all nanoparticles individually at various concentrations for a better comparative study. These coating formulations were applied onto mild steel for anti-bacterial testing that was performed against Escherichia coli and Bacillus. The nanoparticle concentration was varied from 1% (wt) to 6% (wt). The best anti-bacterial result was obtained with 4% (wt) of silica–titania core–shell nanoparticles prepared via the peptization process among all the nanoparticles. The scratch testing was performed successfully using an Erichsen scratch tester; the formulated PU coating passed up-to 20 N load with good adhesion, impact resistance, flexibility and has shown satisfactory anti-corrosion performance.

Halogen‐free flame‐retardant flexible polyurethane for textile coating: Preparation and characterisation

SummaryA type of flexible polyurethane (FPU) based on renewable‐sourced polyol was prepared and then modified with halogen‐free flame retardants, namely, alumina trihydrate (ATH) and triphenyl phosphate (TPhP), to further increase its flame‐resistant properties. The optimum loading for additives was determined based on analysing the changes in physicomechanical properties, thermal properties, and flame‐retardant behaviours of modified FPU materials. An FPU‐coated textile was then prepared; its smoke‐generating behaviours and flammability were investigated in comparison with pristine fabric, pristine FPU, and respective modified FPU. The results confirmed good synergistic effect between ATH and TPhP, which helped increasing flame‐resistant properties of applied materials, while also maintained reasonable flexibility for fabric‐coating applications. However, the usage of modified FPU as coating material also proved to cause more toxic smoke emissions during the short burning duration of coated‐fabric, an issue that needed to be investigated more thoroughly in order to guarantee the safety of people during catastrophic events.

Shape memory properties of interpenetrating polymer networks (IPNs) based on hyperbranched polyurethane (HBPU)

In this article, a type of hyperbranched polyurethane (HBPU) with triazine structure was successfully synthesized. Afterwards, HBPU was applied through grafting epoxy resin (EP) to fabricate the interpenetrating polymer networks (IPNs) with different ratio of HBPU/EP. The structure of HBPU prepolymer and the formation of the HBPU/EP IPNs were characterized and confirmed by Nuclear Magnetic Resonance (NMR) and Fourier Transform Infrared (FTIR) spectroscopy, and the nanoscale phase separation in IPNs composite was analyzed by Atomic Force Microscope (AFM). Besides, the thermal and mechanical results indicated that the IPNs structure enables the material with high strength and thermal stability. Shape memory cycles test demonstrated that the HBPU/EP INPs possess an excellent shape memory performance, and the best shape fixity and recovery were presented by IPNs composite with 20 wt% HBPU.

The influence of elastomeric polyurethane type and ratio on the physicochemical properties of electrospun polyurethane/silk fibroin hybrid nanofibers as potential scaffolds for soft and hard tissue engineering

Hybrid materials and structures have been known as multifunctional polymers used for various commercial productions. Recently, biomaterials have become an emerging research field for tissue engineering applications. In this study, the hybrid fibrous scaffolds of two various types of aliphatic elastomeric polyurethane (EPU) and silk fibroin (SF) were fabricated with different mass ratio by electrospinning. Physical and mechanical properties of these scaffolds were evaluated using scanning electron microscopy, attenuated total reflectance Fourier transform infrared spectroscopy, X-ray diffraction, contact angle measurement, atomic force microscopy and tensile strength analysis. Viability and attachment of human foreskin fibroblasts on the scaffolds were also assessed by MTT assay, hematoxylin-eosin and fluorescentstaining and SEM. The results showed that in both types of polyurethane, by increasing the percentage of fibroin to polyurethane, the fibers diameter decreased and the uniformity of their diameter increased. Unexpected ultrafine fibers and nanowebs were seen throughout the usual fibers of EPU/SF hybrid scaffolds. Thus, the efficiency of the homing and proliferation of the fibroblasts cells onto the scaffolds was improved. Based on our results, the EPU/SF hybrid scaffolds characteristics, especially morphology, mechanical properties and biocompatibility were tunable by altering the ratio and the type of EPU. These features make these adjustable hybrids as suitable scaffolds for reconstitution of a wide range of organs such as skin, liver, uterus, esophagus, vasculature, tracheal cartilage, neurons and others.

Sponge-based microfluidic sampling for potentiometric ion sensing

This work demonstrates an application of the new materials, sponges, for the use in microfluidic solution sampling integrated with ion-selective electrodes. The microfluidic sponge-based sampling was developed and studied as novel sampling and sample handling method to serve as alternative for microfluidic paper- and textile-based sampling for ion analysis in various environmental (Cd2+, Pb2+ and pH) and clinically (K+, Na+, Cl−) relevant samples. Three types of polyurethane, cellulose and natural sponges were used as substrates for microfluidic solution sampling. Polyurethane based sponge was found to have low heavy metal sorption capacity thus it was recognized as suitable for microfluidic sampling coupled with solid-state as well as solid-contact ion-selective electrodes. The application of sponge-based microfluidic sampling, contrary to previous findings of paper- and textile-based microfluidic sampling, allowed measurements of heavy metals without prior modification of the sampling substrate. Finally, the determination of potassium, sodium and chloride in wastewater sludge and sweat samples done with sponge-based microfluidic sampling integrated with ISEs was found similar to analysis done by ICP-OES and IC.

UV-curable self-healing polyurethane coating based on thiol-ene and Diels-Alder double click reactions

Endowing UV-curable coatings with self-healing properties by incorporating dynamic bonds into their cross-linking network is of vital significance. However, in practical applications, self-healing polymers are often plagued with problems such as a high healing temperature and long healing time. To address this challenge, we developed a new type of UV-curable polyurethane coating by the combination of Diels-Alder and thiol-ene click reactions. The Diels-Alder bonds in the polyurethane samples developed in this work furnished perfect mechanical properties and self-healing ability. Self-healing of polyurethane based on Diels-Alder bonds usually occurs at 120 °C. Thiol-ene click reaction is a robust, novel polymerization method, and it improved the structural performance of the polymer with a more homogenous structure being formed than that achieved with traditional UV-curing. Herein, a novel UV-curable self-healing coating, which is referred to as a PU-SH system, was designed by integrating thiol-ene into polyurethane resins containing Diels-Alder bonds. Results of analyses by assorted techniques (including Fourier-transform infrared spectroscopy, different scanning calorimetry, rheology, optical microscopy, and 3D optical interferometric profilometry) strongly indicated that the self-healing ability of the prepared coatings is superior to those of previously studied traditional UV-curing coatings, which are referred to as PU systems. The resultant coatings of the PU-SH system showed a remarkable reduction in the healing temperature from 120 °C for the PU system to 90 ˚C. The rapid scratch-healing properties of the UV-curable coatings, taken together with the moderate healing temperature makes the material attractive for a variety of applications, such as in flexible electronic screens, car paint film, and aircraft interior finishes.

INVESTIGATION OF MECHANICAL BEHAVIOR OF POLYMERIC FOAM MATERIALS REINFORCED BY OIL PALM EMPTY FRUIT BUNCHES (OPEFB) FIBERS DUE TO STATIC AND DYNAMIC LOADS

Polymeric composite foam with EFB fiber reinforced is new material that can be utilized as an alternative engineering material. EFB fiber utilization becomes the center of subject in this research. Moreover, these composites are unique with the presence of cavities (foam) in the matrix of unsaturated polyester resin. It results a decrease in density of the material that formed, and obtain a thermoset polymer composite material lighter than any else similar type. The objective of this study is to obtain the best manufacturing techniques of composite material, the mechanical behavior of these materials due to tensile static loading and high strain rate impact, and the distribution of foam that occur in the material that formed as a result of blowing agent (BA) from the type of polyurethane (PU). In this research, the sample formed into standard specimen of testing, such as ASTM D638 for static tensile test, and impact test specimen. Mechanical’s behaviors that are obtained in this research are density, tensile strength, modulus of elasticity (E), the incident stress, and dynamic modulus of elasticity of the material. For static testing was performed according to standard ASTM D638 tensile and impact test using the Kolsky’s method. To know the distribution of foam that occur in the material, were observed using Scanning Electron Microscope instrument (SEM). To determine the stress distribution in this material, then conducted a computer simulation using Ansys. The best result obtained by the composition of this material based on material composition, which resin consumption can be reduced by the presence of BA as well as mechanical strength, good enough for molding. The best composition in this study will be used in subsequent studies, namely the design and manufacture of traffic cones from this material.

ANALISIS KETAHANAN ABRASI MATERIAL OUTSOLE POLYURETHANE (PU) & NITRILE BUTADINE RUBBER (NBR) PADA SAFETY SHOES CHEETAH DI PT. X

Improved quality, strength and life time in terms of abrasion resistance on safety shoes outsole Cheetah material where the process use of some material has decreased in quality, besides due to usage factors, maintenance factors, and some of these materials also experience problems during use. This study is done to determine the abrasion resistance of each Outsole Polyurethane (PU) material and Nitrile Butadiene Rubber (NBR). Abrasion resistance test on the material method used the DIN Abrasion tester. Retrieval of data on outsole material was carried out on the outsole material with new conditions and that has been used in the field for a period of 1 year with a method of measuring abrasion resistance index and density of material. Calculation of average abrasion resistance for new Polyurethane (PU) type was 37 , 11 mm3 / year, while the average abrasion resistance for Polyurethane (PU) type that has been used for 1 year was 33.19 mm3 / year so that the difference is 3.92 mm3 / year or about 11% quality decrease of abrasion resistance. The average abrasion resistance with the new Nitrile Butadiene Rubber (NBR) type was 108.26 mm3 / year, the average abrasion resistance for Nitrile Butadiene Rubber (NBR) type with conditions already used in 1 year period was 107.44 mm3 / year so that the difference is 0.82 mm3 / year or about 1% decrease in quality decrease of abrasion resistance. Abrasion tolerance limits that have been set according to the SOP (Standard Operational Procedure) against abrasion resistance if SG ≥ 0.9 then the Abrasive Max is 150 and if SG ≤ 0.9 Then the Abrasive Max is 250.