Production Of Polyurethanes Research Articles

Composite coatings based on silicone-modified polyurethane and marine natural product chlorogentisyl alcohol for marine antifouling

Marine biofouling has a serious impact on marine facilities, and traditional antifoulants may cause secondary pollution to the ocean. As chlorogentisyl alcohol (3-chloro-2,5-dihydroxybenzyl alcohol, CHBA) is a marine natural product with excellent antifouling properties, CHBA and its analogues are prepared and combined with silicone-modified polyurethane (SiPU) for development of potential green composite coatings for marine antifouling. Lubricant polydimethylsiloxane and antifoulant CHBA endow the composite material with antifouling properties under dynamic and static conditions, respectively. CHBA is steadily released from the composite coating at a rate of 28 μg/(cm2·d). As one of the CHBA/SiPU composite coatings, SiPU-3 exhibits inspiring activities against Escherichia coli (Gram-negative bacteria), Staphylococcus aureus (Gram-positive bacteria) and Vibriofischeri (marine bacteria), with all inhibition rates exceeding 90.0 %. This composite coating has high antiprotein adsorption ability and algal inhibition rate, showing desirable antifouling performance for up to 90 d in seawater. This work will provide new possible considerations in the development of marine antifouling coatings using marine natural antifoulants.

The influence of washing of rice straw lignin isolation on polyurethane synthesis for coating in biomedical application

This study examined the effectiveness of different washing methods in improving the quality and functionality of rice straw lignin for its application in the synthesis of polyurethane as a coating material for biomedical pulp. The findings demonstrated that lignin subjected to triple washing (LW3) displayed the highest level of purity, as evidenced by elevated values of ph-OH and total phenolic content. LW3 exhibited the lowest syringyl/guaiacyl ratio, however, it had the highest mean molecular weight. Moreover, the LW3 was employed as a precursor for the production of polyurethane. Kidney trays coated with polyurethane demonstrated prolonged resistance to hot and cold water for over 4 h. This coating effectively adhered to the fibers of the tray and sealed the pores, resulting in enhanced water resistance. This study offers valuable insights into the advancement of sustainable biobased materials for the purpose of utilizing agricultural byproducts in the synthesis of polymers for various high-value applications.

Searching of optimal conditions and development of analysis of isocyanate groups in prepolymers

The purpose of the work was to study the options for volumetric analysis of isocyanate groups in prepolymers and to search for factors affecting the accuracy of the analysis in order to identify differences between the values specified by the manufacturer and those obtained in the laboratory.Metods. Intermediate polymerization products based on isocyanates from two or more monomeric units used for the production of polyurethanes, the quality of which is determined by the optimal ratio of isocyanate and hydroxyl groups, were selected as the object of research. The NCO index was determined by the volumetric method based on the interaction of isocyanate groups with diethylamine, with confirmation of the results by methods of mathematical statistics.Results. the work analyzes currently known methods for determining the content of isocyanate groups in prepolymers and identifies differences in the technique of execution. A volumetric method for determining the NCO index based on the interaction of isocyanate groups with diethylamine was used. The solubility of industrial prepolymer samples was evaluated and the dissolution rate was calculated, on the basis of which the optimal volume of the solution and prepolymer samples were determined, providing an accurate determination of the isocyanate number. The adjusted conditions allowed us to reach the required value of the NCO index of the SKU prepolymer, calculated on the basis of static processing of the results and the construction of the Gauss distribution curve. Changes in the methodology make it possible to reach a certified value of the indicator, which allows its use for further calculations in the synthesis of polyurethane.Conclusion. Recommendations for determining the isocyanate index for the analysis of prepolymer by the volumetric method will help to monitor incoming raw materials for compliance with certificates to perform an accurate calculation of raw materials in the synthesis of polyurethane.Key words: prepolymer, polyurethane, isocyanate index, volumetric analysis, diethylamine, solubility.

Synthesis, Structure, and Actual Applications of Double Metal Cyanide Catalysts.

Double metal cyanide (DMC) complexes represent a unique family of materials with an open framework structure. The main current application of these complexes in chemical industry is their use as catalysts (DMCCs) of the ring-opening polymerization of propylene oxide (PO), yielding branched polyols, highly demanded in production of polyurethanes and surfactants. The actual problem of chemical fixing carbon dioxide from the atmosphere gave new impetus to the development of DMCCs, which turned out to be effective in oxirane/CO2 copolymerization. In recent years, new types and formulations of DMCCs were created, so that greater understanding of the reaction mechanisms was achieved and new fields of catalytic applications were found. In the present review, we summarized background and actual information about the synthesis, structure, and mechanisms of the action of DMCCs, as well as their application in the development of new materials and fine chemicals.

Lignin-carbohydrate complex-based polyurethane elastomer with outstanding mechanical strength, photothermal efficiency, and enhanced recyclability

Addressing plastic pollution and reducing reliance on petroleum reserves necessitates the development of bio-based materials from renewable resources. Lignin-carbohydrate complexes (LCC) extracted from lignocellulose, abundant in aromatic rings and hydroxyl groups, offer a promising alternative to conventional polyols in polyurethane synthesis. Historically, the limited solubility of LCC in polyols has posed significant challenges in fabricating high-performance biomass-based polyurethanes. This study presents an innovative LCC-based polyurethane elastomer, synthesized from LCC, polyols, and isocyanate building blocks. By replacing traditional polyols with hydroxyl-rich LCC, the resulting polyurethane elastomer (PUC) exhibits exceptional mechanical properties and photothermal conversion efficiency. The material boasts a maximum tensile strength of 20.94 MPa, a fracture strain of 1167.39 %, an elastic recovery rate of 91.4 %, and a peak photothermal conversion temperature of 125 °C. These outstanding attributes are ascribed to a robust network of dynamic covalent and hydrogen bonds. Moreover, the incorporation of LCC notably enhances the recyclability of the polyurethane elastomer and provides effective UV-blocking properties. This research not only broadens the spectrum of raw materials available for polyurethane production but also introduces innovative methodologies for the practical utilization of LCC, representing a notable advancement in sustainable materials science.

Recent Advances in the Preparation and Application of Bio-Based Polyurethanes.

Amid environmental pollution and resource depletion, developing and utilizing biomass resources as alternatives to petroleum is a prominent research focus. Driven by environmental protection and sustainable development, the shift from petroleum-based to bio-based polyurethane is a prevailing trend in polyurethane material development. Biomass sources such as vegetable oil, polysaccharides, and lignin offer extensive application prospects in bio-based polyurethane production. Functional modifications of these polyurethanes can further expand their application range. This article explores the preparation of various bio-based polyurethanes, their applications across different fields, and their anticipated future development and uses.

Current Trends in the Use of Biomass in the Manufacture of Rigid Polyurethane Foams: A Review

This paper discusses methods of using biomass from the agriculture, forestry, food and aquaculture industries as potential raw materials for bio-polyols and as fillers in the production of rigid polyurethane (RPUR) foams. Various aspects of obtaining bio-polyols are discussed, as well as the impact of replacing petrochemical polyols with bio-polyols on the properties of foams. Special attention is paid to the conversion of vegetable oils and lignin. Another important aspect of the research is the use of biomass as foam fillers. Chemical and physical modifications are discussed, and important factors, such as the type and origin of biomass, particle size and amount, affecting the foaming process, microstructure and properties of RPUR foams are identified. The advantages and disadvantages of using biomass in foam production are described. It is found that bio-polyols can replace (at least partially) petrochemical polyols while maintaining the high insulation and strength of foams. In the case of the use of biomass as fillers, it is found that the shaping of their properties is largely dependent on the specific characteristics of the filler particles. This requires further research into process optimization but allows for the fine-tuning of RPUR foam properties to meet specific requirements.

Nine years of patch testing with isocyanates in a clinic of occupational dermatology.

Isocyanates are used as starting materials of polyurethane (PU) products. They are relatively important occupational skin sensitizers. To analyse results of a large isocyanate patch test series of 19 isocyanate test substances and 4,4'-diaminodiphenylmethane (MDA), a marker of 4,4'-diphenylmethane diisocyanate (MDI) hypersensitivity. Test files were screened for positive reactions in the isocyanate series. Patients with positive reactions were analysed for occupation, exposure and diagnosis. In 2010-2019, 53 patients had positive reactions in the series (16% of 338 patients tested). MDA, the well-established screening substance for MDI allergy, was positive in 30 patients, an in-house monomeric MDI test substance in 23 patients and 3 different polymeric MDI test substances in 19-21 patients. We diagnosed 16 cases of occupational allergic contact dermatitis (OACD) from MDI including 3 pipe reliners. Hexamethylene-1,6-diisocyanate (HDI) oligomers in paint hardeners caused 5 cases of OACD, more cases than 2,4-toluene diisocyanate (TDI; n = 3) and isophorone diisocyanate (IPDI; n = 1) put together. In contrast to previous studies, polymeric MDI test substances were not superior to a monomeric MDI. Pipe reliners may get sensitised not only by epoxy products and acrylates but also by MDI in hardeners of PU pipe coatings. HDI oligomers were the second most important causes of OACD after MDI.

Ageing tests with high temperatures of prototype vibroacoustic isolators – under ballast mats (UBMs) based on recycled materials

This study focuses on experimental ageing tests with high temperatures carried out on prototype under ballast mats (UBMs) according to the procedure of the European standard EN 17282, which was introduced in late 2020. Most of the analysed UBM samples are based on recycled elastomeric materials, such as styrene-butadiene rubber (SBR) granules and fibres from end-of-life car tyres and rebond polyurethane waste from polyurethane product manufacturing plants. Additionally, two variations of the mat based on mineral wool are analysed. Significant differences in the values of static and dynamic characteristics measured before and after the ageing tests are demonstrated, and permanent deformations of the recycled polyurethane-based mats are shown. Moreover, it is proved that the elastomeric mats based on recycled rubber materials (SBR granules and fibres) have high durability and are an effective solution in terms of protection against vibration and structure-borne noise from railway traffic. In addition, the authors propose criteria for assessing the results of the ageing test with high temperatures of UBMs tested according to the procedure of EN 17282.

Green process for Polyurethane: From CO2 to isocyanate

Polyurethane, a highly versatile and widely used polymer, has garnered significant interest as a candidate material for CO2 incorporation to address climate change. Nevertheless, research into alternative production methods for isocyanate, a key monomer in polyurethane production, remains insufficient, despite the heavy reliance of the conventional approach on phosgene, a highly toxic material. This study proposes a sustainable process for synthesizing methylene diphenyl diisocyanate (MDI). The proposed process involves the production of syngas from CO2, followed by syngas separation via a hydrogenation reaction, oxidative carbonylation of amine to form dicarbamate, and subsequent thermal decomposition to yield MDI. The syngas separation via the hydrogenation reaction eliminates the need for an additional separation process by simultaneously separating reaction products and preparing a reactant for the subsequent step. Moreover, the introduction of a Pd/TiO2 catalyst and a new reactant introduction strategy significantly reduces side reactions during oxidative carbonylation, thereby enhancing the overall yield. Process modeling and a life cycle assessment demonstrated substantial environmental advantages over the conventional MDI manufacturing process, highlighting the potential of this approach as a greener alternative.

Synthesis of novel bio-based and degradable polyurethanes using lignin oligomers

Bio-based and degradable materials were proposed to challenge the major problem of plastic disposal in the environment. In this context, polyurethane production was re-evaluated, encouraging the search for replacing both petroleum components and highly toxic species. A novel synthesis route is explored in this work, aimed to produce degradable lignin-based polyurethanes. Oligomers from steam-exploded lignin were extracted and used with ε-caprolactone (ε-CL) to generate a fully bio-based pre-polymer (oligo-grafted-poly(ε-CL)), exploiting ring-opening polymerization. We have demonstrated that tuning the main reaction parameters, such as ε-CL:oligomer and catalyst:ε-CL mass ratios, and reaction time, it is possible to obtain different pre-polymers enabling the synthesis of bio-based polyurethanes with variable physicochemical properties. In particular, the oligomeric content modulates the thermal and mechanical properties of the polymer (melting point range: 54–62 °C; Young modulus range: 3–7 kPa) and enhances the degradability (up to 13 % wt, in acid environment), highlighting the potential of the material for possible applications.

Elucidating the Impact of Polyol Functional Moieties on Exothermic Poly(urethane-urea) Polymerization: A Thermo-Kinetic Simulation Approach

The pursuit of sustainable polyurethane (PU) product development necessitates a profound understanding of precursor materials. Particularly, polyol plays a crucial role, since PU properties are heavily influenced by the type of polyol employed during production. While traditional PUs are solely derived from hydroxyl functionalized polyols, the emergence of amine-hydroxyl hybrid polyols has garnered significant attention due to their potential for enhancing PU product properties. These hybrid polyols are characterized by the presence of both amine and hydroxyl functional groups. However, characterizing these polyols remains a daunting challenge due to the lack of established experimental testing standards for properties, such as fractional hydroxyl and amine moieties and thermo-kinetic parameters for amine reactions with isocyanates. Additionally, characterization methods demand extensive time and resources and pose risks to health and the environment. To bridge these gaps, this study employed computational simulation via MATLAB to determine the moieties’ fractions and thermo-kinetic parameters for hybrid polyols. The computational method integrated energy balance and reaction kinetics analysis for various polyols to elucidate the influence of functional moieties on the thermo-kinetic behavior of PU formations. Validation of the simulated results was conducted by comparing their experimental and simulated prepolymer and foam temperature profiles, highlighting the direct influence of fractional moieties on PU formations. The comparisons revealed an average relative error of less than 5%, indicating the accuracy and credibility of the simulation. Thus, this study represents a pivotal opportunity for advancing knowledge and driving sustainable developments in bio-based polyol characterization for PU production streamlining and formulation optimization.

An integrated cofactor and co-substrate recycling pathway for the biosynthesis of 1,5-pentanediol

Background1,5-pentanediol (1,5-PDO) is a linear diol with an odd number of methylene groups, which is an important raw material for polyurethane production. In recent years, the chemical methods have been predominantly employed for synthesizing 1,5-PDO. However, with the increasing emphasis on environmentally friendly production, it has been a growing interest in the biosynthesis of 1,5-PDO. Due to the limited availability of only three reported feasible biosynthesis pathways, we developed a new biosynthetic pathway to form a cell factory in Escherichia coli to produce 1,5-PDO.ResultsIn this study, we reported an artificial pathway for the synthesis of 1,5-PDO from lysine with an integrated cofactor and co-substrate recycling and also evaluated its feasibility in E.coli. To get through the pathway, we first screened aminotransferases originated from different organisms to identify the enzyme that could successfully transfer two amines from cadaverine, and thus GabT from E. coli was characterized. It was then cascaded with lysine decarboxylase and alcohol dehydrogenase from E. coli to achieve the whole-cell production of 1,5-PDO from lysine. To improve the whole-cell activity for 1,5-PDO production, we employed a protein scaffold of EutM for GabT assembly and glutamate dehydrogenase was also validated for the recycling of NADPH and α-ketoglutaric acid (α-KG). After optimizing the cultivation and bioconversion conditions, the titer of 1,5-PDO reached 4.03 mM.ConclusionWe established a novel pathway for 1,5-PDO production through two consecutive transamination reaction from cadaverine, and also integrated cofactor and co-substrate recycling system, which provided an alternative option for the biosynthesis of 1,5-PDO.

Biodegradation of polyurethanes by Staphylococcus warneri and by microbial co-culture

With the increasing production and use of polyurethanes (PUs), it is necessary to develop sustainable techniques for the remediation of plastic pollution. The use of microorganisms capable of biodegrading PUs may be an environmentally desirable solution for controlling these plastic contaminants. To contribute to the discovery of alternatives for the mitigation of plastics in the environment, this study aimed to explore the potential of StaphylococcuswarneriUFV_01.21, isolated from the gut of Galleria mellonellalarvae, for biodegradation of PU in pure culture and microbial co-culture with Serratia liquefaciensL135. S. warneri grew using Impranil® PU as the sole carbon source in pure culture and co-culture. With six days of incubation, the biodegradation of Impranil® in Luria Bertani broth was 96, 88 and 76%, while in minimal medium, it was 58, 54 and 42% for S. warneri, S. liquefaciens, and co-culture, respectively. In addition, S. warneri in pure culture or co-culture was able to biodegrade, adhere and form biofilms on the surfaces of Impranil® disks and poly[4,4′-methylenebis (phenyl isocyanate)-alt-1,4-butanediol/di(propylene glycol)/polycaprolactone] (PCLMDI) films. Scanning electron microscopy also revealed biodegradation by detecting the formation of cracks, furrows, pores, and roughness on the surfaces of inoculated PU, both with pure culture and microbial co-culture. This study is the first to demonstrate the potential of S. warneriin PU biodegradation.

Tandem Electrooxidation - Reductive Amination of Biobased Isohexides Towards Bicyclic Diamines.

Isohexide-derived diamines are considered preferred precursors for the production of biobased polyurethanes and polyamides. However, current synthesis methods from isohexides suffer from serious issues concerning selectivity and the recyclability of the process auxiliaries (e. g. homogeneous catalysts), which renders a translation to the industry highly unlikely. Here, we report on the production of such diamine building blocks, via a tandem electrooxidation - reductive amination process in which the process auxiliaries can be easily recycled. The application of (immobilized) TEMPO in combination with simple halides (e. g. NaBr) in the electrochemical step even enables the oxidation of the sterically hindered exo-OHs of the isohexides to the corresponding diketones (yield up to 99 %). In the subsequent reductive amination, the produced ketones are atom-efficiently converted to isohexide diamines utilizing NH3, H2, and Ru/C and an acid resin cocatalyst.

Searching for the Achilles' Heel of Urethane Linkage-An Energetic Perspective.

A sudden increase in polyurethane (PU) production necessitates viable recycling methods for the waste generated. PU is one of the most important plastic materials with a wide range of applications; however, the stability of the urethane linkage is a major issue in chemical recycling. In this work, termination reactions of a model urethane molecule, namely methyl N-phenyl carbamate (MPCate), are investigated using G3MP2B3 composite quantum chemical method. Our main goal was to gain insights into the energetic profile of urethane bond termination and find an applicable chemical recycling method. Hydrogenation, hydrolysis, methanolysis, peroxidation, glycolysis, ammonolysis, reduction with methylamine and termination by dimethyl phosphite were explored in both gas and condensed phases. Out of these chemicals, degradation by H2, H2O2 and CH3NH2 revealed promising results with lower activation barriers and exergonic pathways, especially in water solvation. Implementing these effective PU recycling methods can also have significant economic benefits since the obtained products from the reactions are industrially relevant substances. For example, aniline and dimethyl carbonate could be reusable in polymer technologies serving as potential methods for circular economy. As further potential transformations, several ionizations of MPCate were also examined including electron capture and detachment, protonation/deprotonation and reaction with OH-. Alkaline digestion against the model urethane MPCate was found to be promising due to the relatively low activation energy. In an ideal case, the transformation of the urethane bond could be an enzymatic process; therefore, potential enzymes, such as lipoxygenase, were also considered for the catalysis of peroxidation, and lipases for methanolysis.

Utilization of Plant Oils for Sustainable Polyurethane Adhesives: A Review.

The utilization of plant oils as a renewable resource for the production of polyurethane adhesives presents a promising way to improve sustainability and reduce environmental impact. This review explores the potential of various vegetable oils, including waste oils, in the synthesis of polyurethanes as an alternative to conventional petroleum-based raw materials. The investigation highlights the environmental challenges associated with conventional polyurethane production and highlights the benefits of switching to bio-renewable oils. By examining the feasibility and potential applications of vegetable oil-based polyurethanes, this study emphasizes the importance of further research and development in this area to realize the full potential of sustainable polyurethane adhesives. Further research and development in this area are key to overcoming the challenges and realizing the full potential of plant-oil-based polyurethanes in various industrial applications.

In situ epoxidation of canola oil via peracetic acid mechanism-optimization and kinetic study

Canola oil can serve as a substitute for polyol in the production of eco-friendly polyurethane. The aim of this study is to investigate the optimal conditions for the epoxidation of canola oil via the Taguchi optimization method. To date, there is no published work on optimization of process parameters for epoxidized canola oil production using the Taguchi method. In this study, the epoxidation of canola oil was performed using in situ-generated peracetic acid. Peracetic acid was formed by the reaction between acetic acid and hydrogen peroxide in the presence of a catalyst. The highest conversion to oxirane of 85% was achieved at a ratio of 2:1 of hydrogen peroxide to canola oil, a temperature of 65°C, and a stirring speed of 400 rpm. The Fourier-transform infrared spectroscopy (FTIR) characterization reveals the presence of the oxirane ring group, identified at a wavenumber of 1150 cm−1. Employing particle swarm numerical simulations, the results exhibit excellent agreement with the experimental data, thereby confirming the accuracy and validity of the kinetic model.

A novel method for the synthesis of solvent‐free and high‐solid‐content waterborne polyurethanes by introducing a small amount of polyethylene glycol

AbstractIn the study, the synthesis process involved the reaction of dimethylolbutyric acid and polytetramethylene ether glycol 1000 (PTMG1000) with hexamethylene diisocyanate (H12MDI), taking advantage of their mutual dissolution at high temperatures. The chain‐extension reaction with 1,4‐butanediol (BDO) was successfully conducted without the use of organic solvents. The emulsification reaction was carried out using the polyurethane prepolymer at 60% solids content, along with aqueous dispersions of polyethylene glycol (PEG) with varying molecular weights and amounts as interfacially active agents. Fourier transform infrared spectroscopy analysis suggested potential hydrogen bonding interactions between the PEG molecular chain and the polyurethane chain. Rheometer analysis demonstrated a significant reduction in viscosity with the addition of 1–5 wt.% PEG, accompanied by an increase in average particle size. This phenomenon was attributed to the formation of a hydrophilic lubrication layer of PEG around the water‐based polyurethane (WPU) microcells. Among them, WPU films containing 4 wt.% PEG4000 not only exhibited soft properties with a mechanical elongation rate exceeding 2000% but also showed excellent storage stability. The addition of long‐chain PEG facilitated the formation of a lubrication layer between the microcells, contributing to spatial stabilization and reducing particle aggregation at high solids content. It is noteworthy that this solvent‐free process, without any organic solvents, together with the adjusted PEG content, successfully synthesized waterborne polyurethanes with low viscosity and high solids content. This provides a new sustainable and environmentally friendly method for the future production of waterborne polyurethanes.

An Integrated Process Analysis for Producing Glycerol Carbonate from CO2 and Glycerol.

Glycerol carbonate (GC) is one of the most attractive green chemicals involved in several applications such as polymer synthesis, e. g., the production of polyurethanes and polycarbonates. This relevant chemical can be produced, in a green way, using CO2 (from carbon capture) and glycerol (a byproduct from biodiesel manufacturing). Therefore, in this work, a comprehensive analysis of the GC production process is conducted based on the following synthesis route: urea-dimethyl carbonate-GC using carbon dioxide and glycerol as the main raw materials where the synthesis pathway was efficiently integrated using Aspen Plus. A techno-economic analysis was performed in order to estimate the required capital investment and operating cost for the whole GC process, providing insights on individual capital cost requirements for the urea, dimethyl carbonate, and GC production sections. A total capital cost of $192.1 MM, and a total operating cost of $225.7 MM/y were estimated for the process. The total annualized cost was estimated as $1,558 USD/t of GC produced, competitive with current market price.