Types Of Polyurethanes Research Articles

Low carbon polymer modified pavement asphalt originated from Diels-Alder type polyurethane

The continuous challenge in the design of modified asphalt and its mixtures is to enhance performance significantly and reduce energy consumption. For polymer-modified asphalt, the increase in viscosity results in more increase in energy consumption for preparation and use process. Therefore, in this study, the PU based on Diels-Alder bond (DAPU) with good mechanical properties at using temperatures and lower viscosity at high temperatures is prepared to modify asphalt. Fourier transform infrared spectrometer (FTIR) and differential scanning calorimeter are used to prove the successful preparation of DAPU and DAPU modified asphalt. In the viscosity test, both the DAPU and the modified asphalt have lower viscosity (above 135°C). The DAPU-modified asphalt effectively improves resistance to high-temperature deformation and low-temperature cracking by dynamic shear rheometer (DSR) and bending beam rheometer (BBR) tests. This study provides a new method to solve environmental issues in the field of PU-modified asphalt.

Fabrication of Novel Polyurethane matrix-based Functional Composites with Enhanced Mechanical Performance

Thermoplastic polyurethane (TPU) has gained significant interest in several fields, including automobile steering wheels, and the electronics sector due to their easier processability, abrasive resistance, and self-lubricating performances. However, their strong inherent flammability and significant smoke and heat production during burning limit their industrial applications. Therefore, its applicability can be enhanced with the addition of high-strength reinforcement and making them antibacterial and flame-retardant. This research is designed to examine the influence of zirconium phosphate (ZrP) and zinc oxide (ZnO) nanoparticles on the novel polyurethane/glass fiber reinforced composites for flame retardant and antibacterial applications with improved mechanical performance. Three different types of novel polyurethane (PU1, PU2, PU3) matrices were prepared using different recipes, and 7% ZrP and 5% ZnO nanoparticles were added to the polyurethane matrices separately, and their corresponding composite samples were fabricated using glass reinforcement. Mechanical i.e., Charpy impact, hardness and tensile, and functional i.e., flame retardancy (FR) and antibacterial tests were performed to compare their performance. Mechanical testing results showed that PU3-based composite samples showed the highest values of impact force, hardness, and tensile strength in both ZrP and ZnO nanoparticle-based composite samples. Furthermore, 7% ZrP-PU3 composite exhibited the best performance of flame retardancy due to the presence of hexamethylene diisocyanates (HDI) content. Likewise, the 5% ZnO-PU3-based composite exhibited the highest antibacterial activity along with enhanced mechanical performance.

Chiral structures of polymers influence their resistance to protein adsorption and bacterial adhesion as investigated by quartz crystal microbalance with dissipation

Chiral stereochemical strategy for antimicrobial adhesion is a newly-developed method with growing interest. However, the effect of chiral structures on the anti-biofouling property is still unclear. Herein, we employed quartz crystal microbalance with dissipation (QCM-D) to study the ability of two polyurethanes modified by distinct isomers of chiral borneol compounds to inhibit proteins adsorption and bacteria adhesion. Two types of polyurethanes containing endo-L-borneol-based side chains (PLBA) or exo-iso-borneol-based side chains (PIBA) were synthesized through a thiol-ene ‘click’ reaction and polyaddition polymerization. The structure, chirality and surface wettability of the polyurethanes (PLBA-PU/PIBA-PU) were investigated, confirming the intact molecular chirality of borneol and the improved surface hydrophobicity of the polyurethanes after introducing borneol-based side chains. We monitored the protein adsorption and bacteria adhesion on these polyurethane surfaces by QCM-D. The PLBA-PU and PIBA-PU surfaces exhibit enhanced protein resistance and antimicrobial adhesion properties. Moreover, significant difference in anti-biofouling performance was found by QCM-D between PLBA-PU and PIBA-PU, where L-configuration of borneol on the polyurethane surfaces provides enhanced anti-biofouling function compared to exo-iso-borneol.

Preparation and performance study of low heat storage flame retardant polyurethane for coal mines

In order to meet the requirements for the use of polyurethane for reinforcement in mines, the synthesis temperature of polyurethane needs to be lowered, and the flame-retardant and mechanical properties of polyurethane should also be considered comprehensively. Factors affecting the synthesis temperature of polyurethanes are investigated, low heat storage polyurethanes that meet the temperature requirements for use in plugging crushed coal bodies in coal mines are formulated, and the synthesized polyurethanes are characterised for their flame retardant properties by FTIR, SEM, TG-FTIR and CONE experiments. It was found that in this paper, a new type of polyurethane for coal mines was formed by flame retardant modification of polyurethane by adding nano-system flame retardant and phosphorus-system flame retardant, and the synthetic reaction temperature of the material could reach as low as 51.2 °C, and the pyrolysis onset temperature was increased to 286 °C. The experimental results show that the flame retardant property of this synthetic polyurethane has been significantly improved, and the heat accumulation effect of the synthesis process on the surrounding coal body has been greatly reduced. The physical properties and thermal stability of this synthetic polyurethane in the grouting process meet the safety requirements for use in underground coal mines.

Polyurethanes and Their Biomedical Applications.

The tunable mechanical properties of polyurethanes (PUs), due to their extensive structural diversity and biocompatibility, have made them promising materials for biomedical applications. Scientists can address PUs' issues with platelet absorption and thrombus formation owing to their modifiable surface. In recent years, PUs have been extensively utilized in biomedical applications because of their chemical stability, biocompatibility, and minimal cytotoxicity. Moreover, addressing challenges related to degradation and recycling has led to a growing focus on the development of biobased polyurethanes as a current focal point. PUs are widely implemented in cardiovascular fields and as implantable materials for internal organs due to their favorable biocompatibility and physicochemical properties. Additionally, they show great potential in bone tissue engineering as injectable grafts or implantable scaffolds. This paper reviews the synthesis methods, physicochemical properties, and degradation pathways of PUs and summarizes recent progress in applying different types of polyurethanes in various biomedical applications, from wound repair to hip replacement. Finally, we discuss the challenges and future directions for the translation of novel polyurethane materials into biomedical applications.

Effect of the filler content on some physical and mechanical properties of virgin- and recycled thermoplastic polyurethane composites

Effects of thermoplastic polyurethane (TPU) types (Recycled (R) and Virgin (V)) composites with 15 wt% and 30 wt% oakwood flour addition were studied. Selected physical, mechanical, morphological, and thermal properties of resulting polymer composites were analyzed. Test samples were manufactured using injection molding, except that abrasion resistance specimens were manufactured using a compression molding process. The findings indicated that the types of TPU and filler contents played a significant role in the density and mechanical properties of the TPU test samples. The increased oak wood flour contents in both TPU types showed improvement in density, tensile modulus, hardness, flexural strength flexural modulus, dynamic impact strength, and yield strength of the composite while decreasing the elongation at break values. In addition, both TPU types and filler contents significantly affected the densities of V-TPU and R-TPU. The TPUs type, filler content, and cycle-rpm affected Taber’s abrasion resistance values. Weight loss, which increased with the number of cycles for the control samples, decreased with increasing wood flour content. This study aimed to provide an overview of the effect of the wood flour content in the manufacturing of thermoplastic-reinforced composites and to provide a basis for further research and development efforts.

Recycling of Polyurethane Foams via Glycolysis: A Review.

Polyurethane foams constitute highly problematic waste due to their low density and consequently large volume. Among the most promising recycling approaches, the glycolysis of polyurethane waste stands out and was extensively discussed in this article. Existing literature reviews lack a detailed analysis of glycolysis processes and a clear presentation of the most important data. However, in this review, the scientific literature on glycolysis has been thoroughly examined and updated with the latest research in the field. The article provides an overview of glycolysis methods, categorized into rigid and flexible foams, along with a review of the catalysts and process conditions employed. Additionally, this study offers a comprehensive analysis of industrial methods protected by active patents, which has not been previously explored in the literature. This detailed examination of patent information adds significant value to the review and distinguishes it from others. Furthermore, this review also aims to introduce the main types of polyurethanes and their properties. It outlines the fundamentals of recycling strategies, thermomodernization trends, and environmental considerations, highlighting the critical role of recycling in the industry. The article serves as a complete foundation for exploring new alternative methods in this field.

Electroactive and Self‐healing Polyurethane Doped Tin Oxide Interlayers for Efficient Organic Solar Cells†

Comprehensive SummaryTin oxide (SnO2) has been widely used as an electron transport layer (ETL) in optoelectronic devices. However, there are numerous surface or bulk defects in SnO2, working as charge recombination centers to degrade device. Here, an electroactive and self‐healing polyurethane (PHNN) was designed by integrating conjugated unit – naphthalene diimide (NDI) into a typical polyurethane backbone. Numerous hydrogen bonds and π interactions in PHNN work as non‐covalent interactions to endow this polymer with superior self‐healing properties. PHNN contains lots of aliphatic amine and carbonyl groups, which effectively passivate the defects in SnO2. The π stacking of NDI units will facilitate electron delocalization, endowing PHNN with electrical activity compared with traditional polyurethane. Doping SnO2 with PHNN can improve the conductivity and reduce the work function of SnO2 layer, which is conducive to efficient charge extraction and transport. Using PHNN doped SnO2 as ETL for PM6: Y6 and PM6: BTP‐eC9 based inverted organic solar cells can achieve a high efficiency of 17.16% and 17.51%, respectively. Devices containing doped SnO2 ETL show significantly improved efficiency and stability. Thus, the electroactive polyurethane doped SnO2 interlayers show high performance interfacial modification to align energy‐levels in solar cell devices, which have promising applications in organic electronics.

Suitability of aromatic polyurethanes for use in nuclear applications

Plastic bags are used to facilitate the storage and transport of nuclear materials. In case the storage container becomes damaged, these bags act as a protection barrier against possible contamination. Polyvinyl chloride (PVC) is a polymer commonly used in such applications, but unfortunately, it contributes to the corrosion of the metal container due to HCl evolution. Thus, this work evaluated aging effects on chemical and thermo-mechanical properties of aromatic polyurethanes with the intent to find a replacement for PVC. Aromatic poly(ether)urethanes were aged for up to 21 months under combined gamma irradiation and thermal treatment conditions. A few samples were also placed into actual nuclear storage containers and aged for a similar time period. Experimental techniques, such as FT-IR, NMR, mass spectrometry, TGA, DSC, and tensile tests were employed to characterize two types of polyurethanes, one with and another one without a flame-retardant additive. Our unique aging approach shows that these aromatic polyurethanes are well placed to substitute PVC bags and thus, avoid corrosion of storage metal containers used by the nuclear industry.

Thermal Stability and Heat Transfer of Polyurethanes for Joints Applications of Wooden Structures.

Wood characterized by desired mechanical properties and wood joining material is essential for creating wooden structures. The polymer adhesives are suitable for such applications due to the possibility of energy dissipation from stresses generated by wooden structures and the elimination of thermal bridging, which are common problems in metal joining materials. This research focuses on the thermophysical properties of the laboratory-prepared flexible and rigid polyurethanes to select an appropriate polymer adhesive. Our results showed that the highest thermal stability was in the case of the new PSTF-S adhesive, which reached 230 °C, but the lowest mass loss in the air environment was around 54% for the PS material. The mean thermal expansion coefficient for F&R PU adhesives was 124-164∙10-6 K-1. The thermal diffusivity of examined adhesives varied between 0.100 and 0.180 mm2s-1. The thermal conductivity, depending on the type of polyurethane, was in the 0.13-0.29 W∙m-1∙K-1 range. The relative decrease in thermal diffusivity after heating the adhesives to 150 °C was from 2% for materials with the lowest diffusivity to 23% for the PU with the highest value of heat transfer. It was found that such data can be used to simulate wooden construction joints in future research.

Elastic Polyurethane as Stress-Redistribution-Adhesive-Layer (SRAL) for Directly Integrated High-Energy-Density Flexible Batteries.

The low mechanical reliability and integration failure are key challenges hindering the commercialization of geometrically flexible batteries. This work proposes that the failure of directly integrating flexible batteries using traditional rigid adhesives is primarily due to the mismatch between the generated stress at the adhesive/substrate interface, and the maximum allowable stress. Accordingly, a stress redistribution adhesive layer (SRAL) strategy is conceived by using elastic adhesive to redistribute the generated stress. The function mechanism of the SRAL strategy is confirmed by theoretical finite element analysis. Experimentally, a polyurethane (PU) type elastic adhesive (with maximum strainof 1425%) is synthesized and used as the SRAL to integrate rigid cells on different flexible substrates to fabricate directly integrated flexible battery with robust output under various harsh environments, such as stretching, twisting, and even bending in water. The SRAL strategy is expected to be generally applicable in various flexible devices that involve the integration of rigid components onto flexible substrates.

The cytotoxicity assessment of different clear aligner materials

Background/purposeInvisible orthodontic treatments are becoming increasingly popular, and numerous brands of invisible aligners are now available. However, concerns remain about the safety of the materials used in these products. This study aimed to assess the cytotoxic effects of both original and thermoformed thermoplastic materials used in orthodontic aligners on human periodontal ligament (HPDL) cells in vitro. Materials and methodsThe experiment used six different brands, each containing three types of thermoplastic materials, Polyethylene terephthalateco-1, 4-cyclohexylenedimethylene terephthalate (PETG), thermoplastic polyurethane (TPU), and copolyester polyethylene terephthalate (PET). The original sheets and the thermoformed materials were soaked in a culture medium for seven and fourteen days, and then applied to cultured human periodontal ligament cells. Cells were harvested on the first, third, and fifth days after application, and their viability was analyzed using the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] assay. ResultsThe findings revealed that some thermoformed materials, notably PETG, exhibited lower survival rates compared to their non-thermoformed versions. However, other materials such as TP and PET maintained over 70% cell viability, indicating only minor cytotoxic effects. ConclusionThese findings highlight the need for further research into the long-term biocompatibility of these materials but generally affirm their safety for use in orthodontic aligners under the tested conditions.

Recent Advances in Preparation and Structure of Polyurethane Porous Materials for Sound Absorbing Application.

Various acoustic materials are developed to resolve noise pollution problem in many industries. Especially, materials with porous structure are broadly used to absorb sound energy in civil construction and transportation area. Polyurethane (PU) porous materials possess excellent damping properties, good toughness, and well-developed pore structures, which have a broad application prospect in sound absorption field. This work aims to summarize the recent progress of fabrication and structure for PU porous materials in sound absorption application. The sound absorption mechanisms of porous materials are introduced. Different kinds of structure for typical PU porous materials in sound absorption application are covered and highlighted, which include PU foam, modified PU porous materials, aerogel, templated PU, and special PU porous materials. Finally, the development direction and existing problems of PU material in sound absorption application are briefly prospected. It can be expected that porous PU with high sound absorption coefficient can be obtained by using some facile methods. The design and accurate regulation of porous structures or construction of multilayer sound absorption structure is favorably recommended to fulfill the high demand of industrial and commercial applications in the future work.

Natural Fiber Reinforced Shoe Midsoles with Balanced Stiffness/Damping Behavior.

The comfort of walking depends heavily on the shoes used. Consequently, the midsole of shoes is designed in such a way that it can dampen force peaks during walking. This significantly increases the overall wellness during walking. Therefore, the midsole usually consists of rubber-like polymers, such as polyurethane and ethylene-vinyl acetate copolymer. Furthermore, the manufacturing process of these polymers results in a foam-like structure. This further enhances the damping behavior of the material. Nevertheless, it would be desirable to find a cheap and sustainable method to enhance the damping behavior of the shoe midsole. The purpose of this work is to see if hemp fibers, which are part of the polymer matrix material, could improve the stiffness without losing the damping behavior. The mechanical properties of such prepared fiber-reinforced composites were characterized by quasi-static tensile testing and dynamic mechanical analysis. The mechanical properties were examined in relation to the fiber type, weight fraction, and type of polyurethane used. Furthermore, the investigation of the embedding of these fibers in the polymer matrix was conducted through the utilization of optical and electron microscopy.

Polyurethane Adhesives for Wood Based on a Simple Mixture of Castor Oil and Crude Glycerin

Developing a new type of polyurethane is essential because conventional options often exhibit shortcomings in terms of environmental sustainability, cost-effectiveness, and performance in specialized applications. A novel polyurethane adhesive derived from a simple mixture of castor oil (CO) and crude glycerin (CG) holds promise as it reduces reliance on fossil fuels and harnesses renewable resources, making it environmentally friendly. Simple CO/CG mixtures, adjusted at three different weight fractions, were used as bio-based polyester polyols to produce polyurethane adhesive for wood bonding. The resulting products are yellowish liquids with moderate-to-high viscosity, measuring 19,800–21,000 cP at 25 °C. The chemical structure of the polyester polyols was characterized using infrared spectroscopy (FTIR), thermogravimetry (TG), and differential scanning calorimetry (DSC). These polyols reacted with polymeric 4,4-methylene diphenyl diisocyanate (p-MDI) at a consistent isocyanate index of 1.3, resulting in the formation of polyurethane adhesives. Crucially, all final adhesives met the adhesive strength requirements specified by ASTM D-5751 standards, underscoring their suitability for wood bonding applications. The addition of CG enhanced the surface and volumetric hydrophobicity of the cured adhesives, resulting in adhesive properties that are not only stronger but also more weather-resistant. Although the thermal stability of the adhesives decreased with the inclusion of CG, FTIR analysis confirmed proper polyurethane polymer formation. The adhesive adjusted for a 2:1 CO:CG weight ratio promoted wood–wood bonding with the highest shear strength, likely due to a higher formation of urethane linkages between hydroxyl groups from the blend of polyols and isocyanate groups from the p-MDI.

The vibration energy dissipation behaviour of 3D-PAM type RVD

Considering that ordinary rubber materials have problems such as insufficient mechanical properties and poor shock absorption effect, a right-angle viscoelastic damper (RVD) based on 3D printed auxetic metamaterial (3D-PAM) is proposed in this paper. According to the refined finite element simulation, a dynamic energy dissipation study was conducted on the RVD. Firstly, the 3D-PAM was fabricated by selective laser sintering printing technique, and its material properties were demonstrated. Secondly, the 3D-PAM type RVD was simulated by ABAQUS to study the characteristics of dynamic energy dissipation and to investigate the stress distribution and displacement variation of the 3D-PAM layer. The results show that the hysteresis curve shape is smooth and full under all working conditions. The hysteresis loop shows linear characteristics under small displacement amplitude. As displacement amplitude increases, a hardening nonlinear response is observed. The maximum loss factor of the 3D-PAM type RVD reaches 0.64. Under the same thickness and loading conditions, the maximum loss factor has increased by 16.4% and 100.0% respectively compared to Polyurethane type RVD and Fluororubber type RVD. In conclusion, results indicate that the 3D-PAM type RVD designed in this project exhibits superior energy dissipation characteristics.

Multifunctional, robust, and self‐healable polyurethane coatings cross‐linked by Diels–Alder reaction of calix[4] arenes containing furan groups

AbstractSelf‐healing coatings can restore their performance after inevitable damage and are promising in the industry owing to their longer service life and lower repair cost. The use of Diels–Alder reaction bonds is well‐known to generate thermally self‐healing coatings. In this study, a series of cross‐linked self‐healing polyurethane (PU) coatings were synthesized through Diels–Alder reactions of p‐tert‐butyl calix[4]arene bearing furan groups (C4A‐FA) as a new chain extender and a bismaleimide (BMI) polyether amine as a Diels–Alder cross‐linking agent. Adding C4A‐FA to PUs improves their mechanical properties, thermal stability, and self‐healing ability. Additionally, these modifications can result in the formation of composite networks with PU that exhibit thermoreversibility and self‐healing properties. These changes have led to PUs containing modified calix[4]arene (C4A‐FA) having better properties compared with unmodified calix[4]arene PUs. The properties of prepared coatings were evaluated by Fourier transform infrared spectroscopy, scanning electron microscope, differential scanning calorimetry (DSC), thermogravimetric analyses (TGA), and tensile tests compared with a typical PU sample. The tensile and TGA results show an improvement in the thermal and mechanical properties of the polymers by increasing the C4A‐FA content. By replacing 15% of butandiol (BDO) with C4A‐FA in PU pure, the tensile strength increased from 1.69 to 5.14 MPa. Furthermore, adding diels–alder (DA) bonds enhanced the tensile strength to 10.49 MPa for PU‐C4A15‐DA. According to DSC results, a broad endothermic peak from nearly 80–140°C confirmed the retro‐DA reactions in the synthesized thermoreversible samples. The healing efficiency of the PU‐C4A15‐DA sample was obtained at 92.5% (measured by tensile test), which is the highest value among cross‐linked self‐healing PUs reported in the literature.

Moisture diffusion and tensile properties of epoxy-based and polyurethane-based flax-glass hybrid FRP under hygrothermal and weathering environments

This research presents tensile modulus and strength of flax-glass hybrid FRP (HFRP) flat coupons with different fibre volume fractions and fabric stacking sequences under constant hygrothermal (50 °C and 95% RH) and cyclic weathering (water spray-ultraviolet radiation) environments for six months. Two types of polymer (i.e., epoxy (EP) and polyurethane (PUR)) were employed in HFRP. Fourier transformed infrared spectroscopy (FTIR) was performed to identify the changes in functional groups of flax fibres and polymer matrix after exposures. The glass transition temperature (Tg) of polymer matrix was measured by differential scanning calorimetry (DSC), which was used to study the influence of environmental exposure on Tg. The 3D diffusion coefficients of EP-based flax FRP and glass FRP laminates were determined based on experimental moisture uptake and Fick's law. A coupled mass diffusion-stress analysis based on finite element (FE) model was conducted to simulate the moisture diffusion and swelling behaviour of HFRP. The results showed that hygrothermal and weathering exposures hardly affected tensile modulus of HFRP regardless of the matrix type. After the environmental exposure, EP-based HFRP experienced lower retention ratio of tensile strength (65.4–88.0%) compared to PUR-based HFRP (80.7–94.1%) because of higher moisture absorption in the EP-based HFRP. The influence of fabric stacking sequence on tensile strength reduction varied with different fibre volume fractions in EP-based HFRP, which was explained by the combined effects of the internal stress and damage propagation at flax-glass interface.

Liquid-Free, Self-Repairable, Recyclable, and Highly Stretchable Colorless Solid Ionic Conductive Elastomers for Strain/Temperature Sensors.

Solid-state ionic conductive elastomers (ICEs) can fundamentally overcome the disadvantages of hydrogels and ionogels (their liquid components tend to leak or evaporate), and are considered to be ideal materials for flexible ionic sensors. In this study, a liquid-free ionic polyurethane (PU) type conductive elastomer (ICE-2) was synthesized and studied. The PU type matrix with microphase separation endowed ICE-2 with excellent mechanical versatility. The disulfide bond exchange reaction in the hard phase and intermolecular hydrogen bonds contributed to damage repairing ability. ICE-2 exhibited good ionic conductivity (2.86×10-6 S/cm), high transparency (average transmittance >89 %, 400~800 nm), excellent mechanical properties (tensile strength of 3.06 MPa, elongation at break of 1760 %, and fracture energy of 14.98 kJ/m2 ), appreciable self-healing ability (healing efficiency >90 %), satisfactory environmental stability, and outstanding recyclability. The sensor constructed by ICE-2 could not only realize the perception of temperature changes, but also accurately and sensitively detect various human activities, including joint movements and micro-expression changes. This study provides a simple and effective strategy for the development of flexible and soft ionic conductors for sensors and human-machine interfaces.

The Presence of Microplastics in the Gills and Gastrointestinal Tract of Mackerel (Rastrelliger Kanagurta Cuvier, 1816) from Jakarta Bay, Indonesia.

This study examined the characteristics of microplastics (MPs) in the gills and gastrointestinal tract (GIT) of mackerel (Rastrelliger kanagurta) captured in Jakarta Bay, Indonesia. All 120 fish contained MPs, with fragment > fiber > film being the most prevalent types, in that order. The total abundances of fragments, fibers, and films in the gills were as follows: 4.8 ± 1.6, 1.0 ± 0.7, and 0.3 ± 0.3, respectively. The total abundances of fragments, fibers, and films in the GIT were 5.9 ± 2.3, 1.3 ± 0.8, and 0.4 ± 0.4, respectively. Statistical analysis showed that the abundance of fragments, fibers and films in both the gills and GIT of mackerel did not differ significantly between sampling locations. In the gills and GIT, MPs with sizes less than 0.1mm and MPs that were black in color were most prevalent. Fourier transform infrared (FTIR) spectroscopy tests on MPs from the tissues of mackerel showed that there were 8 different types of MP polymers, namely, latex, nylon, polymethyl methacrylate (PMMA), cellulose acetate (CA), polyurethane (PU), polycarbonate (PC), polystyrene (PS), and polytetrafluoroethylene (PTFE). Latex and polycarbonate were detected in fish samples from Jakarta Bay.