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Intensive research is currently being carried out worldwide to replace fossil raw materials with renewable ones or waste based on chemical synthesis. However, it is important that the newly developed raw materials do not conflict with global food production and recommend the use of non-edible or waste raw materials. Therefore, modified non-edible oilseed radish oil was used in the synthesis of polymeric materials. The functionalization of the oil was achieved through one-step, solvent-free transesterification process with triethanolamine, diethylene glycol, polypropylene glycol, ethylene glycol and propylene glycol. Biopolyols with hydroxyl numbers in the range of 237–346 mg KOH/g and different chemical structures were obtained. Open-cell polyurethane foams were produced by replacing 100% of the original petrochemical polyol with the biopolyols. The influence of the chemical structures of the biopolyols on the properties of the thermal insulation materials was analysed. The foams were characterised by low apparent densities of about 16 kg/m3. The type of biopolyol did not have a significant influence on the mechanical strength of the foams. A thermal analysis of the polyurethane biofoams was also carried out. [ABSTRACT FROM AUTHOR]

Polyurethane foam compositions derived from bioderived polyester polyols with various additives were evaluated for disintegration under composting conditions using the ISO 20200 standard and were characterized by thermogravimetric analysis, microscopy, infrared spectroscopy, and imaging to provide additional insight. Compared to polyether polyol-based polyurethanes, the bioderived polyurethanes were found to display increased disintegration with an average mass loss of 25.4 ± 3.6 weight percent when subjected to composting conditions for 45 days, suggesting that these materials are less likely to persist in the environment when compared to other types of commodity plastics. Additives such as carbon black and lignin added within the foam composition did not accelerate the disintegration. [ABSTRACT FROM AUTHOR]

This work focused on the preparation and investigation of polyurethane (SO-PU)-containing sunflower oil glycerides. By transesterification of sunflower oil with glycerol, we synthesized a glyceride mixture with an equilibrium composition, which was used as a new diol component in polyurethanes in addition to poly(ε-caprolactone)diol (PCLD2000). The structure of the glyceride mixture was characterized by physicochemical methods, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), nuclear magnetic resonance spectroscopy (NMR), and size exclusion chromatography (SEC) measurements. The synthesis of polyurethanes was performed in two steps: first the prepolymer with the isocyanate end was synthesized, followed by crosslinking with an additional amount of diisocyanate. For the synthesis of the prepolymer, 4,4′-methylene diphenyl diisocyanate (MDI) or 1,6-hexamethylene diisocyanate (HDI) were used as isocyanate components, while the crosslinking was carried out using an additional amount of MDI or HDI. The obtained SO-PU flexible polymer films were characterized by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The so-obtained flexible SO-PU films were proved to be suitable for the preparation of potentially biocompatible and/or biodegradable scaffolds. In addition, the stress versus strain curves for the SO-PU polymers were interpreted in terms of a mechanical model, taking into account the yield and the strain hardening. [ABSTRACT FROM AUTHOR]

In this study, a new epoxidized oil from Citrullus colocynthis seed oil (CCSO) was obtained for a potential application in the formulation of polyurethane coatings. Initially, the fatty acid composition of CCSO was determined by gas chromatography–mass spectrometry (GC–MS). Subsequently, the epoxidation of CCSO was performed with in situ generated peracetic acid, which was formed with hydrogen peroxide (30 wt.%) and glacial acetic acid and catalyzed with sulfuric acid. The reaction was continued at a molar ratio of 1.50:1.0 of hydrogen peroxide to double bond (H2O2:DB) for 6 h at a controlled temperature of 60 °C. The resulting epoxidized oil was then used to produce a bio-based polyol by hydroxylation. The molar ratio of epoxy groups to methanol and distilled water was maintained at 1:11:2, and the reaction was carried out for 2 h at a controlled temperature of 65 °C. The major functional groups of the epoxidized oil and its polyol were validated by Fourier-transform infrared (FT-IR) and proton nuclear magnetic resonance (1H NMR) spectroscopies. A polyurethane (PU) coating was produced from the synthesized polyol and 3HDI isocyanurate, keeping the molar ratio of NCO:OH at 1:1. The resulting PU coating was then applied to glass and aluminum panels (Al 1001). After the film was cured, the properties of the PU coating were evaluated using various techniques including pencil hardness, pendulum hardness, adhesion, gloss, chemical resistance, and EIS tests. The results show that the PU coating obtained from CCSO is a promising new raw material for coating applications. [ABSTRACT FROM AUTHOR]

The search for innovative and sustainable solutions to improve the energy efficiency of the construction industry has been a hot topic for researchers due to the tremendous impact of insulator materials in the thermal comfort of buildings. In the present work, an innovative lightweight composite material with thermal insulation properties was developed, for the first time, by using cardoon particles and polyurethane. The formulation of the composite material was optimized in terms of cardoon fraction and the polyol/isocyanate ratio, to achieve the best compromise between internal bond (IB) strength and thickness swelling (TS). The best performing composite was PU75-CP45, with 45 wt% of cardoon particles and 75% of isocyanate, achieving an IB of 0.41 MPa and a TS of 5.3%. Regarding insulation properties, the PU75-CP45 composite material exhibits a promising performance when compared to conventional construction industry materials by tuning its thickness. Additionally, the composite material presented very low emissions of volatile organic compounds and formaldehyde (bellow to legislation levels) and high resistance to biological degradation. [ABSTRACT FROM AUTHOR]

Polyurethane (PU) is among the most universal polymers and has been extensively applied in many fields, such as construction, machinery, furniture, clothing, textile, packaging and biomedicine. Traditionally, as the main starting materials for PU, polyols deeply depend on petroleum stock. From the perspective of recycling and environmental friendliness, advanced PU synthesis, using diversified resources as feedstocks, aims to develop versatile products with excellent properties to achieve the transformation from a fossil fuel-driven energy economy to renewable and sustainable ones. This review focuses on the recent development in the synthesis and modification of PU by extracting value-added monomers for polyols from waste polymers and natural bio-based polymers, such as the recycled waste polymers: polyethylene terephthalate (PET), PU and polycarbonate (PC); the biomaterials: vegetable oil, lignin, cashew nut shell liquid and plant straw; and biomacromolecules: polysaccharides and protein. To design these advanced polyurethane formulations, it is essential to understand the structure–property relationships of PU from recycling polyols. In a word, this bottom-up path provides a material recycling approach to PU design for printing and packaging, as well as biomedical, building and wearable electronics applications.

Polyurethanes (PU) are unique heteropolymers with a wide range of physicomechanical properties, fields of use and high development potential. PU is obtained by condensation of diisocyanate and various polyol compounds. The peculiarities of the structure and synthesis of commercial polyols based on the products of secondary oil processing, namely oligomeric glycols, oxides and dicarboxylic acids are presented. [ABSTRACT FROM AUTHOR]

Developing polyols from biomass sources contributes to a more circular economy by replacing petroleum-based polyols in the vast production of polyurethanes (PUR). One such potential biomass source could be leftover birch bark from which suberinic acids (SA) can be obtained. The purpose of this study was to identify the best synthesis routes for novel SA-based polyols, obtain rigid PUR foams, and evaluate their competitiveness and potential suitability as thermal insulation material. Novel polyols were synthesized from depolymerized SA by esterification with various functionality and molecular weight alcohols in several molar ratios. The moisture content, hydroxyl and acid values, and apparent viscosity were tested. Free-rise rigid PUR foams from the most suitable SA-based polyol and tall oil-based polyol were successfully prepared, reaching ~20 wt.% total renewable material content in the foam. The obtained rigid PUR foams' morphological, mechanical, and thermal properties were investigated and compared to present foam materials, including commercial foams. The apparent density (~33 kg/m3), as well as the closed cell content (~94%), compression strength (0.25 MPa, parallel to the foaming direction), and thermal conductivity (~0.019 W/(m·K)), approved the competitiveness and potential ability of SA-based rigid PUR foam production as thermal insulation material. [ABSTRACT FROM AUTHOR]

Cardiac tissue engineering (CTE) is a promising way for the restoration of injured cardiac tissue in the healthcare system. The development of biodegradable scaffolds with appropriate chemical, electrical, mechanical, and biological properties is an unmet need for the success of CTE. Electrospinning is a versatile technique that has shown potential applications in CTE. Herein, four different types of multifunctional scaffolds, including synthetic-based poly (glycerol sebacate)-polyurethane (PGU), PGU-Soy scaffold, and a series of trilayer scaffolds containing two outer layers of PGU-Soy and a middle (inner) layer of gelatin (G) as a natural and biodegradable macromolecule without simvastatin (S) and with simvastatin (GS), an anti-inflammatory agent, were fabricated in the sandwich-like structure using electrospinning technique. This approach offers a combination of the advantages of both synthetic and natural polymers to enhance the bioactivity and the cell-to-cell and cell-to-matrix intercommunication. An in vitro drug release analysis was performed after the incorporation of soybean oil (Soy) and G. Soy is used as a semiconducting material was introduced to improve the electrical conductivity of nanofibrous scaffolds. The physicochemical properties, contact angle, and biodegradability of the electrospun scaffolds were also assessed. Moreover, the blood compatibility of nanofibrous scaffolds was studied through activated partial thromboplastin time (APTT), prothrombin time (PT), and hemolytic assay. The results showed that all scaffolds exhibited defect-free morphologies with mean fiber diameters in the range of 361 ± 109 to 417 ± 167 nm. A delay in blood clotting was observed, demonstrating the anticoagulant nature of nanofibrous scaffolds. Furthermore, rat cardiomyoblast cell lines (H9C2) were cultured on scaffolds for 7 days, and the morphology and cell arrangement were monitored. Data indicated an appropriate cytocompatibility. Of note, in the PGU-Soy/GS nanofibrous scaffold, a high survival rate was indicated compared to other groups. Our findings exhibited that the simvastatin-loaded polymeric system had positive effects on cardiomyoblasts attachment and growth and could be utilized as a drug release carrier in the field of CTE. [ABSTRACT FROM AUTHOR]

A novel castor oil‐based multifunctional polyol (CM) is fabricated through mild thiol‐ene photo induced reactions using castor oil (CO) and 1‐thioglycerol (MPD) as building blocks. The effect of the reaction time, molar ratio of thiol to carbon–carbon double bond, and the loadings of photo‐initiator are optimized. The resulting CM is combined with CO and employed as cross‐linkers to prepare castor oil‐based water‐borne polyurethane emulsion with desirable mechanical properties and water resistance. Owing to the incorporation of CM cross‐linker with high hydroxyl value of 371 mg KOH/g (which is 2.27 times higher than that of the CO), the prepared castor oil‐based waterborne polyurethane (CMWPU) possesses compacted 3D network structure with high cross‐linking degree, leading to improved glass transition temperature (45 °C), tensile strength (10.8 MPa), water contact angle (87.4°), and decreased water absorption rate (16.12%) with 20% CM additions. Overall, this work illustrates the feasibility of introducing bio renewable CM combined with CO to develop castor oil‐based WPU employing a sustainable development strategy. [ABSTRACT FROM AUTHOR]

To study the rheological and aging properties of vegetable oil–based polyurethane (V-PU) modified asphalt, V-PU terminated with an –NCO group was synthesized from renewable castor oil, and liquefied MDI-100LL and 10–40 wt% V-PU modified asphalts were prepared. Temperature classification, multiple stress creep recovery (MSCR), and linear amplitude scanning (LAS) tests were carried out. The results showed that the modulus, the creep recovery rate (R), and the yield stress and yield strain of the V-PU modified asphalts significantly increased in the order: 0 wt% < 10 wt% < 20 wt% < 40 wt% < 30 wt%, while the phase angle and the unrecoverable creep compliance (Jnr) changed in the opposite order, and the high temperature grade of 30 wt% V-PU modified asphalt was 4 grades higher than that of the base asphalt, which indicated that the addition of V-PU enhanced the fatigue, permanent deformation, and recovery deformation resistance. The 30 wt% sample exhibited phase inversion had the best performance. Comprehensive FTIR, GPC, and fluorescence microscopy analyses showed that the molecular weight significantly increased and the V-PU molecules agglomerated after aging. The excess –NCO groups of V-PU prepolymer react with water in the air and the active hydrogen in the asphalt system and finally form a cross-linked three-dimensional network structure with the asphalt to improve performance. The mechanism of intramolecular cementation reaction and the aging process of V-PU modified asphalt was creatively derived. [ABSTRACT FROM AUTHOR]

Polyurethane (PU), currently replacing existing synthetic materials worldwide, is a synthetic polymer derived from polyols, isocyanates, and a chain extender added by condensation reactions. PU wastes which are difficult to recycle, are commonly discarded in landfills and flow into ecosystems, thereby causing serious environmental problems. In recent years, insect-associated microbes have become a promising, eco-friendly strategy as an alternative to plastic recycling. This study aimed to evaluate the potential of Serratia sp. HY-72 strain isolated from the intestine of the Asian mantis (Hierodula patellifera) for PU degradation. The 65 kDa family I.3 lipase which degrades PU was identified and characterized, with a specific activity of 2,883 U mg−1 . The bacterial filtrates and the recombinant lipase degraded Impranil (a colloidal polyester-PU dispersion, 100 g l−1 ) by 85.24 and 78.35% after 72 h incubation, respectively. Fourier transform infrared spectroscopy analysis revealed changes in Impr anil functional groups, with decreased C=O functional group and aliphatic chain signals, and increased N-H bending with C-N stretching and C-O stretching. The current study also revealed that the HY-72 strain biodegraded the commercial PU foams (polyester- and polyether- PU) with 23.95 and 10.95% weight loss after 2 weeks, respectively with changes in surface morphology and structure such as cracks, roughness, and surface roughening. Altogether, this is one of the few studies reporting biodegradation of PU by the insect associated microbe. These findings suggest that the insect-associated microbe could be a promising resource for biodegradation and recycling of plastic waste. [ABSTRACT FROM AUTHOR]

We report on the development of open-cell polyurethane foams based on bio-polyols from vegetable oils: hemp seed oil, oilseed radish oil, rapeseed oil and used rapeseed cooking oil. The crude oils were pressed from seeds and subjected to an optimal solvent-free epoxidation process. Bio-polyols were obtained by a ring-opening reaction using diethylene glycol and tetrafluoroboric acid as catalysts. The resultant foams were analysed in terms of their apparent density, thermal conductivity coefficient, mechanical strength, closed cell content, short-term water absorption and water vapour permeability, while their morphology was examined using scanning electron microscopy. It was found that regardless of the properties of the oils, especially the content of unsaturated bonds, it was possible to obtain bio-polyols with very similar properties. The foams were characterized by apparent densities ranging from 11.2 to 12.1 kg/m3, thermal conductivity of <39 mW/m∙K, open cell contents of >97% and high water vapour permeability. [ABSTRACT FROM AUTHOR]

Polyurethanes are gaining increasing interest for their use as structural components subjected to cyclic loads, such as leaf springs. Thermoset polyurethane (PUR) based technology offers some advantages, such as fatigue resistance, low viscosity, and fast curing. However, current PUR formulations present two major drawbacks: their petrochemical origin and high reactivity. The aim of this work was to develop a novel biobased PUR (BIO-PUR) with the required mechanical properties and processability for manufacturing structural composites by resin transfer moulding (RTM). For this purpose, a high functionality and high hydroxyl index castor-oil-based polyol was used combined with a biobased glycerol (BIO-Gly) to increase the crosslinking density and improve the final properties of the BIO-PUR. The viscosity and reactivity of the different systems were studied by means of rheology tests and differential scanning calorimetry (DSC). Thermal and mechanical properties were studied by dynamic mechanical analysis (DMA) and flexural tests. Furthermore, the RTM process of a representative part was simulated and validated through the manufacturing and testing of plates. The properties of the BIO-PUR resin systems were strongly influenced by the addition of biobased glycerol and its effect on the crosslinking density. The combination of a high functionality and hydroxyl index biobased polyol with the biobased glycerol resulted in a high-performance BIO-PUR with the required reactivity and final properties for structural applications. [ABSTRACT FROM AUTHOR]

Fatty epoxides are produced from the corresponding alkenes by oxidation in the presence of peracids or other oxidants. The classic method is the Prilezhaev epoxidation in which peracids are generated by in situ oxidation of formic or acetic acids with hydrogen peroxide. Epoxidized vegetable oils and esters are used directly as biobased plasticizers and stabilizers for poly(vinyl chloride) or as important platform chemicals for the oleochemical industry. Nucleophilic attack at the oxirane moiety affords a variety of ring opened monomeric or polymeric products, which in many cases undergo further synthetic modification to yield finished products. The most common nucleophiles include water, alcohols, carboxylic acids, acid anhydrides, and amines, although numerous others can also lead to valuable functionalized fatty derivatives. This review summarizes the chemistry of fatty epoxide ring opening reactions as well as applications of the resultant products. Literature from the last 20 years will be emphasized, although older publications of particular significance will be included. Important applications include biobased lubricants as well as polyols for subsequent production of polyurethanes. In addition, ring‐opening reactions hitherto unreported on fatty oxiranes will be suggested to facilitate further advancements in the chemistry and utility of fatty epoxides. Finally, interest in fatty epoxides and their consequent products will continue to grow due to the simplicity, efficiency, and versatility of oxirane formation and ring opening as well as the continued societal transition away from petroleum to a sustainable, circular, low‐carbon, and biobased economy. [ABSTRACT FROM AUTHOR]

Polyurethane (PU) is one of the most versatile polymers available and can be found in an infinite number of formats ranging from rigid or flexible foams to elastomers. Currently, most Rigid PU Foam (RPUF) waste is landfilled, even though a small amount is mechanically recycled, in which the material is conditioned in size to a very fine powder, which is introduced as a filler. In this work, chemical recycling of two types of rigid PU foams is studied, the major difference being the aliphatic or aromatic nature of the isocyanate used in the synthesis. A solvolysis process is developed, a chemical depolymerization that breaks the chains by means of a chemical agent, a solvent, in the presence of a catalyst and under controlled process conditions. The glycolysis products are purified by vacuum distillation, centrifugation, and acid water treatment, depending on the most suitable process for each waste type. Optimal process conditions are established to obtain high-purity green polyols by performing a set of catalytic glycolysis reactions at laboratory scale with the previously conditioned RPUF waste samples. The physicochemical properties of the polyols, such as hydroxyl value, acid value, average molecular weight (Mn), and viscosity, are analyzed. The chemical structure and thermal stability of the polyols are studied by means of FTIR and TGA, respectively. Partial substitution of the commercial polyol (up to 15 wt.%) by the recycled polyols for RPUF synthesis is studied and characterized. [ABSTRACT FROM AUTHOR]

This study investigated the synthesis of bio-based polyurethane (PU) film from palm kernel oil-based polyols (PKO-p) at four different isocyanate-to-polyols (NCO/OH) ratios comprising 100/100, 100/150, 100/200, and 100/250. The PU film was prepared by mixing 2,4-methylene diphenyl diisocyanate (MDI) and PKO-p in acetone using the pre-polymerization technique under a nitrogen atmosphere at room temperature. The effect of the NCO/OH ratio on the properties of the PU films was analyzed through infra-red spectroscopy, molecular weight distribution, thermal behavior, and impedance spectroscopy. According to the infra-red spectroscopic analysis, the formation of urethane linkages (--NHCOO--) after the polymerization was indicated through the disappearance of isocyanate (N=C=O) peak and the appearances of secondary amine, carbonyl, carbamate, ether, and ester groups in the PU chain. In addition, the Gel Permeation Chromatography (GPC) showed that the weight of average molecular weight (MW) increased with increasing NCO/OH ratio up to 1.23 x 106 g mol-1. Nevertheless, higher content of PKO-p resulted in a low crosslink PU (4 % crosslink) and poor physical properties such as soft, sticky, and easy to tear due to the non-hydrogen bonded urethane. Moreover, the glass-transition temperature (Tg) reduced from 67 °C to 30 °C with the increase in PKO-p content. Despite all samples experienced the same thermal stability at 187 °C, a significant difference was observed in the mass loss of NCO/OH ratios. The highest thermal degradation was found at (100/200) NCO/OH ratio with Tmax = 444 °C. Furthermore, the piezoelectricity characteristic of pristine PU recorded the bulk resistant of up to ~107 -- 105 Ω which reduced further after the presence of lithium iodide (LiI) salts as the charge carrier with the calculated ionic conductivity around 10-5 S cm-1. Thus, this study demonstrated the promising physicochemical properties of PU film from PKO-p for polymer electrolyte application. [ABSTRACT FROM AUTHOR]

The utilization of renewable resources has increased over the last few years in different fields due to environmental and economic concerns. Cashew nut shell liquid (CNSL) is cheaper, abundantly available, and an eco‐friendly agro‐waste product, which holds the potential to significantly replace petro‐based phenols. Present work focusses on the preparation of (i) Cardanol‐based polyols (resol) in different ratios [Cardanol: formaldehyde 1:1.2(Rol1), 1:1.6 (Rol2), and 1:2.0 (Rol3)], (ii) their polyurethanes, and (iii) freestanding, transparent, flexible and thin films/coatings obtained through "Green" route. The effect of curing temperature on the overall performance of films/coatings has also been investigated. The films/coatings obtained by baking at 80 ± 5°C (BK‐Rol1/2‐PU) exhibited improved physicomechanical performance compared with films/coatings obtained at room temperature (RT‐Rol1/2‐PU). BK‐Rol1/2‐PU and RT‐Rol1/2‐PU demonstrated excellent chemical stability. XRD revealed that both BK‐Rol2‐PU and RT‐Rol1/2‐PU films were amorphous and TGA confirmed that BK‐Rol2‐PU showed higher thermal stability compared with RT‐Rol2‐PU films. The contact angle measurements indicated a higher hydrophobic character of BK‐Rol1/2‐PU (96°) relative to RT‐Rol1/2‐PU (90°). These polyurethane films/coatings can be used for protective and decorative purposes. As BK‐Rol1/2‐PU films/coatings outperformed RT‐Rol1/2‐PU, the overall results confirmed that curing temperature had a remarkable effect on the performance characteristics of coatings/films. [ABSTRACT FROM AUTHOR]

The operation of mechanical equipment inevitably generates vibrations and noise, which are harmful to not only the human body but also to the equipment in use. Damping materials, which can convert mechanical energy into thermal energy, possess excellent damping properties in the glass transition region and can alleviate the problems caused by vibration and noise. However, these materials mainly rely on petroleum-based resources, and their glass transition temperatures (Tg) are lower than room temperature. Therefore, bio-based materials with high damping properties at room temperature must be designed for sustainable development. Herein, we demonstrate the fabrication of bio-based millable polyurethane (BMPU)/hindered phenol composites that could overcome the challenges of sustainable development and exhibit high damping properties at room temperature. BMPUs with a high Tg were prepared from modified poly (lactic acid)-based polyols, the unsaturated chain extender trimethylolpropane diallylether, and 4,4′-diphenylmethane diisocyanate, and 3,9-Bis-{1,1-dimethyl-2[β-(3-tert-butyl-4-hydroxy-5-methylphenyl-)propionyloxy]ethyl}-2,4,8,10-tetraoxaspiro [5,5]-undecane (AO-80) was added to prepare BMPU/AO-80 composites. Finally, the properties of the BMPUs and BMPU/AO-80 composites were systematically evaluated. After adding 30 phr of AO-80, the Tg and maximum loss factor (tan δmax) of BMPU/AO-80 composites increased from 7.8 °C to 13.5 °C and from 1.4 to 2.0, respectively. The tan δmax showed an improvement of 43%. Compared with other polyurethanes, the prepared BMPU/AO-80 composites exhibited higher damping properties at room temperature. This study proposes a new strategy to reduce society's current dependence on fossil resources and design materials featuring high damping properties from sustainable raw materials. [ABSTRACT FROM AUTHOR]

The world production of polyurethanes (PU) currently exceeds 18 mln. tons. Moreover, it is expected that, by 2024, it will become greater than 24 mln. tons. We present a survey of works available from the literature and analyzing the methods of recycling of polyurethanes aimed at the reduction of the amount of PU wastes, environmental protection, and prevention of waste dumping in the landfills. Mechanical processing proves to be the oldest and simple method used for the processing of PU wastes. The process of chemical recycling of polyurethane by glycolysis is regarded as the most environmentally friendly and economically competitive method. Glycolysis of polyurethane is a process of chemical depolymerization based on the reaction of transesterification of polyols and glycols in a molecule of urethane. This process makes it possible to destroy the polyurethane matrix and either to release polyol or to generate new recycled polyol. The possibility of application of different glycols and catalysts in the reaction of catalytic transesterification is demonstrated. [ABSTRACT FROM AUTHOR]

In this study, nineteen unmodified lignins from various sources (hardwood, softwood, wheat straw, and corn stover) and isolation processes (kraft, soda, organosolv, sulfite, and enzymatic hydrolysis) were used to replace 30 wt.% of petroleum-based polyol in rigid polyurethane/polyisocyanurate (PUR/PIR) foam formulations. Lignin samples were characterized by measuring their ash content, hydroxyl content (Phosphorus Nuclear Magnetic Resonance Spectroscopy), impurities (Inductively Coupled Plasma), and pH. After foam formulation, properties of lignin-based foams were evaluated and compared with a control foam (with no lignin) via cell morphology, closed-cell content, compression strength, apparent density, thermal conductivity, and color analysis. Lignin-based foams passed all measured standard specifications required by ASTM International C1029-15 for type 1 rigid insulation foams, except for three foams. These three foams had poor compressive strengths, significantly larger cell sizes, darker color, lower closed-cell contents, and slower foaming times. The foam made with corn stover enzymatic hydrolysis lignin showed no significant difference from the control foam in terms of compressive strength and outperformed all other lignin-based foams due to its higher aliphatic and p-hydroxyphenyl hydroxyl contents. Lignin-based foams that passed all required performance testing were made with lignins having higher pH, potassium, sodium, calcium, magnesium, and aliphatic/p-hydroxyphenyl hydroxyl group contents than those that failed. [ABSTRACT FROM AUTHOR]

• Rebiopolyols – new components. • New products characterized by a lower carbon footprint. • Chemolysis of polyurethane biofoams. • Polyurethane systems in which 100 % of the petrochemical polyol was replaced with new repolyols. The primary goal of the research presented here was to evaluate the possibility of chemolysis of polyurethane biofoams synthesized from vegetable oil-based biopolyols with different chemical structures. As a reference material, a foam synthesized in 100 % from a petrochemical polyol was used. Chemolysis of polyurethane foams was conducted by using diethylene glycol as a solvent with a 1.5:1 wt ratio of biopolyurethane scraps to glycol. The reaction was carried out at 180 °C for 100 min in the presence of potassium hydroxide as a catalyst. The results of the chemolysis of different polyurethane foams were evaluated in terms of the hydroxyl number, amine value, viscosity, molecular weight and FTIR analysis of the new rebiopolyols. It can be concluded that the chemical structures of different biopolyols (obtained through the method of transesterification of vegetable oils with two different reagents and a two-step method of epoxidation and oxirane rings opening) that are used to make biopolyurethane foams have an impact on the course of the chemolysis process and the properties of resultant rebiopolyols. In order to verify the application possibilities of the new components obtained in accordance with the idea of circular economy, extreme conditions were applied in the form of complete replacement of the polyol in the reference foam with the rebiopolyols. It was found that replacing the petrochemical polyol with the repolyol results in partial cell opening, and replacing this component with the rebiopolyols results in open-cell foams. Only the rebiopolyol derived from the biofoam with the biopolyol obtained by transesterification of oil with triethanolamine was not suitable for use in a polyurethane system because its reactivity was too high. In conclusion, there is no need to use catalysts to obtain new biofoams from rebiopolyols given the catalytic nature of the new biocomponents. [ABSTRACT FROM AUTHOR]

The preparation and characteristics of rigid polyurethane foams (RPUFs) synthesized from polyols obtained by glycolysis of post-industrial waste RPUFs have been studied. More precisely, waste rigid foams that have been chemically recycled by glycolysis in this work are industrially produced pieces for housing and bracket applications. The glycolysis products have been purified by vacuum distillation. The physicochemical properties of the polyols, such as hydroxyl value, acid value, average molecular weight (Mn) and viscosity have been analyzed. The chemical structure and thermal stability of the polyols have been studied by means of FTIR and TGA, respectively. Partial substitution of the commercial polyol (up to 15 wt.%) by the recycled polyols increases the reactivity of the RPUFs synthesis, according to short characteristic times during the foaming process along with more exothermic temperature profiles. Foams formulated with recycled polyols have a lower bulk density (88.3–96.9 kg m−3) and smaller cell sizes compared to a conventional reference RPUF. The addition of recycled polyols (up to 10 wt.%) into the formulation causes a slight decrease in compressive properties, whereas tensile strength and modulus values increase remarkably. [ABSTRACT FROM AUTHOR]

Polyurethane (PU) is one of the most versatile polymers available and can be found in an infinite number of formats ranging from rigid or flexible foams to elastomers. Currently, most Rigid PU Foam (RPUF) waste is landfilled, even though a small amount is mechanically recycled, in which the material is conditioned in size to a very fine powder, which is introduced as a filler. In this work, chemical recycling of two types of rigid PU foams is studied, the major difference being the aliphatic or aromatic nature of the isocyanate used in the synthesis. A solvolysis process is developed, a chemical depolymerization that breaks the chains by means of a chemical agent, a solvent, in the presence of a catalyst and under controlled process conditions. The glycolysis products are purified by vacuum distillation, centrifugation, and acid water treatment, depending on the most suitable process for each waste type. Optimal process conditions are established to obtain high-purity green polyols by performing a set of catalytic glycolysis reactions at laboratory scale with the previously conditioned RPUF waste samples. The physicochemical properties of the polyols, such as hydroxyl value, acid value, average molecular weight (Mn), and viscosity, are analyzed. The chemical structure and thermal stability of the polyols are studied by means of FTIR and TGA, respectively. Partial substitution of the commercial polyol (up to 15 wt.%) by the recycled polyols for RPUF synthesis is studied and characterized.

Polyurethanes as one of the leading elastomers are explored in academics as well as in industry. These are segmented macromolecules having alternate sequence of soft and hard segments. Structure-property correlation between these segments has been extensively reported in the literature. PUs are used widely in coatings, varnishes, glues, foams, adhesives, sealants, automobile parts, synthetic leather etc. Its application in biomedical devices is also growing rapidly. It is therefore need to highlights the recent developments in this fast growing field. The present article is summarized the conventional and ecofriendly synthetic routes for the preparation of PUs. Conventionally, PUs was synthesized by isocyanates route, later shortcoming of this method explore new synthesis method in which either used biobased polyol or non isocyanates route for preparation of ecofriendly PUs. The applications of different types of PUs coating in various fields are also highlighted in this review. [ABSTRACT FROM AUTHOR]

In this article, we have studied the thermal, chemical, and mechanical properties of the polyurethane artificial leather. Polyurethane artificial leathers were made from polyol, diisocyanate, chain extender, a catalyst, polyester circular knitted fabric, and warp knitted fabric. After manufacturing the artificial leathers, the properties of six different samples were investigated according to the NCO index. The equivalence ratios of the isocyanates to polyols containing a hydroxyl group are referred to as the NCO index. Samples were synthesized with an NCO index of 1.0, 1.4, and 1.8 by changing the weight ratio of diisocyanate. The result showed that as the NCO index increased, the unreacted NCO functional groups and cross-link increased and the mechanical properties of the polyurethane artificial leather were increased. The mechanical properties of circular knitted fabric polyurethane artificial leather were superior than warp knitted fabric polyurethane artificial leather. [ABSTRACT FROM AUTHOR]

The preparation and characteristics of rigid polyurethane foams (RPUFs) synthesized from polyols obtained by glycolysis of post-industrial waste RPUFs have been studied. More precisely, waste rigid foams that have been chemically recycled by glycolysis in this work are industrially produced pieces for housing and bracket applications. The glycolysis products have been purified by vacuum distillation. The physicochemical properties of the polyols, such as hydroxyl value, acid value, average molecular weight (Mn) and viscosity have been analyzed. The chemical structure and thermal stability of the polyols have been studied by means of FTIR and TGA, respectively. Partial substitution of the commercial polyol (up to 15 wt.%) by the recycled polyols increases the reactivity of the RPUFs synthesis, according to short characteristic times during the foaming process along with more exothermic temperature profiles. Foams formulated with recycled polyols have a lower bulk density (88.3–96.9 kg m−3) and smaller cell sizes compared to a conventional reference RPUF. The addition of recycled polyols (up to 10 wt.%) into the formulation causes a slight decrease in compressive properties, whereas tensile strength and modulus values increase remarkably.

The present study is a cradle-to-gate Life Cycle Assessment of a hypothetical production process of rigid polyurethane foam obtained from thistle seed oil, grown on the marginal soils of the Umbria region, Italy. Thistle is a particularly rustic crop, suitable for difficult soil and climatic conditions that allow its cultivation in the Mediterranean area on marginal lands and with only the water supply of the autumn-spring rains. Life Cycle Inventory was built on up-to-date inventory for thistle production, while experimental data for polyol and synthesis were obtained from literature, with reference to a pilot scale reactor. Energy recovery of lignocellulosic biomass and sensitivity analysis were also included in the study. Life Cycle Assessment was performed using SimaPro 9.0 and impacts were evaluated with the Impact2000+ method. Results show the overall impact of thistle oil including its final use for the production of polyurethane foam, and underline the important contribution as environmental benefit of the use of biomass leftovers in the agricultural phase. Moreover, results show that the major impacts of the rigid polyurethane foam production process were related to the synthesis of the foam itself. Among the previous phases constituting the process of synthesis of the polyol, the most impactful one was the cultivation; the oil processing stage, on the other hand, had a small global impact. The synthesis of the foam, taken individually, generated a greater impact than the entire synthesis process of the vegetable polyol starting from the cultivation of thistle. [ABSTRACT FROM AUTHOR]

In this article, we have studied the thermal, chemical, and mechanical properties of the polyurethane artificial leather. Polyurethane artificial leathers were made from polyol, diisocyanate, chain extender, a catalyst, polyester circular knitted fabric, and warp knitted fabric. After manufacturing the artificial leathers, the properties of six different samples were investigated according to the NCO index. The equivalence ratios of the isocyanates to polyols containing a hydroxyl group are referred to as the NCO index. Samples were synthesized with an NCO index of 1.0, 1.4, and 1.8 by changing the weight ratio of diisocyanate. The result showed that as the NCO index increased, the unreacted NCO functional groups and cross-link increased and the mechanical properties of the polyurethane artificial leather were increased. The mechanical properties of circular knitted fabric polyurethane artificial leather were superior than warp knitted fabric polyurethane artificial leather. [ABSTRACT FROM AUTHOR]

• Fluoride-responsive degradable unit can be incorporated into PUs with a range of adhesive properties. • The mechanical properties can be tuned by varying structure and density of H-bonding monomers. • Introducing crystallinity into the adhesives can lower the bonding temperature to 50 °C. • The adhesives undergo depolymerisation to facilitate debonding on addition of fluoride ions. This paper reports the solvent-free synthesis of a series of six fluoride responsive debond-on-demand polyurethane (PU) adhesives that contain a silyl functionalised degradable unit (DU). To optimise the adhesion strength and debonding nature of the adhesives, the chemical composition of the PUs was varied according to the structure of the polyol or the diisocyanate component in the polymer mainchain. 1H NMR spectroscopy was used to study the depolymerisation behaviour in solution state. It showed that tetra -butylammonium fluoride (TBAF) triggered the breakdown of the DU unit without fragmenting the polyol mainchain indiscriminately. On exposure to fluoride ions, the PUs underwent depolymerisation with reductions in M n ranging from 64 to 90% as measured by GPC analysis. The morphology and thermal properties of the PUs were characterised by differential scanning calorimetry (DSC), rheology and variable temperature (VT) SAXS/WAXS analysis. Each technique demonstrated the reversibility of the supramolecular polymer network under thermal stimuli. PUs containing poly(butadiene) soft segments were amorphous with glass transition and viscoelastic transition temperatures dependent on the nature of the soft segment and diisocyanate starting materials. The PU containing a polyester soft segment exhibited a defined melting point at 49 °C. Mechanical stress-strain analysis of the series of PUs showed each exhibited greater than 70% reduction in toughness after treatment with TBAF for 30 min as a consequence of the chemo-responsive degradation of the polymer mainchain. The material featuring an ester-based polyol demonstrated excellent adhesion at bonding temperatures as low as 60 °C. Moreover, this material could be thermally rebonded if broken by force without loss in adhesion strength over three debond-rebond cycles. Lap shear adhesion tests showed a reduction in adhesive strength of approximately 40% (from 11.4 MPa to 7.3 MPa) on exposure to fluoride ions. [ABSTRACT FROM AUTHOR]

Polyurethanes (PUs) consisting of m -xylylene diisocyanate (XDI) exhibit excellent thermal stability and optical properties. To further enhance the optical properties, 1,3-bis(isocyanatomethyl)cyclohexane (H 6 XDI) is considered a potential isocyanate for optically clear adhesives; however, a detailed analysis of the adhesion mechanism has not been investigated. Herein, we synthesized PUs using diisocyanates (XDI, H 6 XDI) and polyols [polypropylene glycol (PPG), polycaprolactone diol (PCL), and polycarbonate diol (PCD)]. To investigate the adhesion mechanism, the interaction between each PUs and functionalized self-assembled monolayers was analyzed using a Surface Forces Apparatus at the nanoscale. Additionally, macroscopic surface energy measurement and probe tack testing were performed. Overall, higher hydrophobic interaction in PCD-containing PUs and predominant hydrogen bonding in PPG-containing PUs was measured. Also, hydrophobic interaction was stronger for H 6 XDI compared to that of XDI in all polyols. These findings clarified polyol-dependent adhesion mechanisms of XDI- and H 6 XDI-based PUs and could be used to design PUs with controlled strength of hydrogen bonds and hydrophobic interactions. [Display omitted] • XDI- and H 6 XDI-based PUs are polymerized by using various types of polyols. • Interaction mechanisms of each PUs are evaluated at the nanoscale using an SFA. • Macroscale adhesion of each PUs is evaluated by probe tack testing. • Contribution of H-bonding and hydrophobic interaction for each PUs are determined. • These results can be utilized for designing XDI and H 6 XDI PUs for various purposes. [ABSTRACT FROM AUTHOR]

Silylation of epoxidized soybean oil (ESBO) was carried out by epoxy ring opening reaction of methoxy and ethoxy silane compounds.¹ H NMR and FTIR spectra confirmed that two novel bio-based polyols, PSiTh and PSiAm, were obtained through the ring opening of epoxy by the mercapto and amino moieties of MPTMS and APTES, respectively. Polyurethanes of these polyols were prepared using 4,4´ - methylene-bis(phenyl isocyanate) (MDI) to incorporate silanol groups into polymer network and were labeled as PUSiTh and PUSiAm, respectively. To see the impact of silanol and phosphorous groups on flame retardant properties, the chain extended polyurethanes, PUSiThCE and PUSiAmCE were also prepared with bisphenol-A bis (hydroxy phenyl phosphonate) (BABHPP). Polyurethanes bearing thio-ether bonds besides alkoxy silane groups were characterized using FTIR spectroscopy. Prepared foams exhibited significant thermal stability and flame retardant properties with a limiting oxygen index (LOI) of 22-24%. Chain extended polyurethanes had 11-13 % higher LOI value than the corresponding non-chain extended polyurethanes. [ABSTRACT FROM AUTHOR]

• We developed a novel self-healing and shape memory polyurethane elastomer with superior mechanical properties by controlling the different molecular weight of the polyol and incorporating dynamic disulfide bonds for reversibility. • We have identified a potential application for the self-healing flexible substrate in flexible electronics. The self-healing polyurethane films have received significant attention due to their unique shape memory behaviors and the hydrogen bonding arising from the urethane linkages. However, it is still a challenge to develop self-healing polyurethane with transparent, high impact resistance, and excellent shape recovery and mechanical properties. In particular, polycarbonate-based polyurethane shows transparency, weatherability and excellent mechanical properties. In this work, transparent self-healing polyurethane film with robust mechanical properties (breaking stress of 26 MPa and elongation at break of 630%) was synthesized by controlling the different molecular weight of the polycarbonate diol and incorporating dynamic disulfide bonds for reversibility. As a result, the self-healing polyurethane film showed an excellent self-healing ability with 98% healing efficiency and excellent shape memory ability with a recovery efficiency of ˃92%. In addition, we have identified a potential application for the self-healing flexible substrate in flexible electronics because of their stable electrical resistance even upon mechanical deformation. [ABSTRACT FROM AUTHOR]

• High-pressure CO 2 sorption on polyol and isocyanate was monitored by FT-NIR. • Upon mixing, reaction under high pressure was monitored by FT-NIR. • Sorbed CO 2 slowed down synthesis reaction due to catalyst deactivation and dilution. • At 0.07 g/g CO 2 catalytic sites were saturated, only dilution further contributed. • CO 2 supercritical state is not relevant to the reaction kinetics. The effect of CO 2 on the polyurethane synthesis between a polyol and an isocyanate was studied by in situ near infrared spectroscopy in a newly developed instrumented foaming equipment. In particular, first two solutions, namely a polyol/CO 2 solution and an isocyanate/CO 2 solution were formed at high pressure and then, upon mixing, the synthesis was promoted, still under pressure. Near infrared spectroscopy in reflection mode was used to monitor both CO 2 sorption in the polyol and in the isocyanate and the polyurethane synthesis under pressure. Results revealed a significant slowing down effect by the sorbed CO 2 , apparently due to two concurrent mechanisms, namely catalyst deactivation and dilution. [ABSTRACT FROM AUTHOR]

• Polymer particles were stabilised into a PP by using a silica gel as NAD. • A NAD concentration of 1.5 wt% was enough for producing a PPP having 38.69 wt% of solids. • PPPs of low viscosity were developed. • A reaction temperature of 80 °C allowed the maximum SM conversion. • The vinyl grafting and the hydroxyl stabilization role of the NAD were demonstrated. Currently, the PU industry is developing new products with enhanced physical, mechanical and structural properties. One of the specialties that is attracting more and more attention from managers and enterprises all over the world are the PUs based on polymer polyether polyols (graft polyols). In this work, the synthesis of graft polyols was developed employing a non-aqueous dispersant (NAD) based on silica gel, which contains in its chemical structure segments with a great affinity for the solid polymeric particles and other segment having a strong affinity for the hydroxyl groups of the liquid polyol. The combination of both polar and non-polar characteristics ensures the stability of the resulting polymer dispersion and prevent the sedimentation and the coalescence of the polymer particles. By using this NAD it was possible to synthesize trifunctional polymer polyether polyol (PPP) from Styrene and containing up to 38.69 wt% of solids. The optimal reaction conditions have been stablished using a concentration of 1.5 wt% NAD, 4 wt% of initiator respect to the monomer amount and a polymerization temperature of 80 °C. The viscosity of the optimal PPP (1930 mPa·s) and the particle size (dv 0.5 of 5.427 μm and dn 0.5 of 1.711 μm) were in the range of graft polyols available in the market for similar solids content, with the additional advantage of employing a lower quantity of NAD and a softer reaction temperature than those employed in the industrial process (110 °C). [ABSTRACT FROM AUTHOR]

A screening Life Cycle Assessment (LCA) of tall oil-based bio-polyols suitable for rigid polyurethane (PU) foams has been carried out. The goal was to identify the hot-spots and data gaps. The system under investigation is three different tall oil fatty acids (TOFA)-based bio-polyol synthesis with a cradle-to-gate approach, from the production of raw materials to the synthesis of TOFA based bio-polyols at a pilot-scale reactor. The synthesis steps that give the most significant environmental footprint hot-spots were identified. The results showed the bio-based feedstock was the main environmental hot-spot in the bio-polyol production process. Future research directions have been highlighted.

In this study, we investigated the Polyurethane paint based on palm oil with the addition of nanoparticles montmorillonite as a heat-resistant. The composites with 1 wt%, 3 wt% and 5 wt% of bentonite filler content obtained by synthesizing in situ were investigated and compared to the neat polyurethane matrix material. The processing of bentonite for montmorillonite was done through several stages including: sedimentation, ultrasonication, dried, sieved with a 200 mesh sieve, then characterized. Untreated MMT were isolated and modified with CTAB. The addition of MMT into polyurethane, as much as 5% wt, can increase the heat as evidenced by the TGA test. The TGA results indicated an enhanced thermal stability, as compared to the neat polyurethane. The onset degradation of neat polyurethane and weight reduction began at a temperature of 50-150°C and completely decomposed at the temperatures of 380°C and for PU MKS-MMT reduction, the initial weight started at a temperature of 150-200°C in 5 %wt and decomposed in the end at a temperature of 490°C. In this research, we also tested the gloss adhesive polyurethane with the addition of MMT; the result stated that the addition of 5%wt MMT can improve the adhesion of polyurethane. The addition of MMT in polyurethane can also enhance the gloss polyurethane compared with polyurethane coated without the addition of MMT.

Buffing Dust (BD), a proteinous solid tennery waste, was used as a reinforcement filler in rigid polyurethane foams (RPUFs). RPUFs were modified with buffing dust, in the range of 0.1–5 wt% in relation to the total polyol mass. It was found that BD addition leads to noticeable changes in several properties, mainly foam morphology, apparent density, thermal conductivity and mechanical strength. The results show that compared to the reference foam, composition modified with 0.1 wt% of BD provides higher density (36.9 kg/m 3 ), greater compression strength (216 kPa), less water uptake (9% after 24 h) and comparable thermal conductivity (0.026 W/m·K). The results obtained in this study confirm that the addition of BD over a certain optimal level has a negative effect on the cell morphology, which leads to deterioration of the physico-mechanical properties of the modified foams. [ABSTRACT FROM AUTHOR]

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A poly(hydroxybutyl citrate) p(HBC) was obtained. The product compound produced in the solution during esterification, was added to rigid polyurethane-polyisocyanurate foams (PUR-PIR). The amount of petrochemical polyol in the foams was decreased in favor of the p(HBC) from 0.1 to 0.5 equivalent. The foams were foamed in two ways: with distilled water (W foams) and with Solkane 365/227 (S foams). The examination results of both foam series were compared. They showed that the foams foamed with water have higher softening temperature than the foams foamed with solkane. The retention values for both foam series are around 91-95%, and water absorption in the range of 0.7-3.2%. The anisotropy coefficient did not exceed 1.08 (the lowest value being 1.01). [ABSTRACT FROM AUTHOR]

Polyphenylene ether (PPE) telechelic macromonomers are unique hydrophobic polyols which have been used to prepare amphiphilic block copolymers. Various polymer compositions have been synthesized with hydrophilic blocks. Their macromolecular nature affords a range of structures including random, alternating, and di- and triblock copolymers. New macromolecular architectures can offer tailored property profiles for optimum performance. Besides reducing moisture uptake and making the polymer surface more hydrophobic, the PPE hydrophobic segment has good compatibility with polystyrene (polystyrene-philic). In general, the PPE contributes to the toughness, strength, and thermal performance. Hydrophilic segments go beyond their affinity for water. Improvements in the interfacial adhesion between polymers and polar substrates via hydrogen bonding and good compatibility with polyesters (polyester-philic) have been exhibited. The heterogeneity of domains in these PPE based block copolymer offers important contributions to diverse applications. [ABSTRACT FROM AUTHOR]

The facile chemical fixation of 18 wt.% carbon dioxide by catalytic carbonation of sorbitol glycidyl ether, monitored by means of NMR and FTIR spectroscopy, affords sorbitol-based cyclic ether carbonate (SEC) as versatile intermediate for producing renewable non-isocyanate polyhydroxydroxyurethane (NIPU) materials. In sharp contrast to the solid, crystalline and highly insoluble pure sorbitol tricarbonate (STC), melting above 200 °C close to its decomposition temperature, SEC is liquid at room temperature and fully miscible with a wide variety of polyfunctional amine curing agents. Despite high SEC carbonate functionality (4.2 mol/kg), both gel time and pot-life time measurements confirm easy processing by curing SEC with polyfunctional aliphatic amines to produce new families of sorbitol-based NIPU materials. Particularly, blends combining flexible long-chain diamines such as dimer fatty acid based diamine (Priamine™ 1074) or polyether triamine (Jeffamine™ T403), respectively, with rigid short-chain diamines such as 1,6-hexamethylene diamine (HMDA), 1,12-dodecyl diamine (DDA), 2,2,4-trimethylhexamethylene diamine (TMHMDA) and isophorone diamine (IPDA), enable the simultaneous incorporation of soft and hard segments into NIPU networks. Moreover, miscible blends of SEC with STC remain liquid up to high STC content. Unparalleled by conventional bio-based NIPU chemistry, the curing of SEC or miscible SEC/STC blends, respectively, with IPDA yields sorbitol-based NIPU thermosets exhibiting significantly improved thermal and mechanical properties, as reflected by high glass transition temperatures surpassing 180 °C and Young moduli exceeding 4000 MPa. [ABSTRACT FROM AUTHOR]

A low cost abundant and renewable vegetable oil source has been gaining increasing attention due to its potential to be chemically modified to polyol and thence to become an alternative replacement for the petroleum-based polyol in polyurethane production. In this study, jatropha oil-based polyol (JOL) was synthesised from non-edible jatropha oil by a two steps process, namely epoxidation and oxirane ring opening. In the first step, the effect of the reaction temperature, the molar ratio of the oil double bond to formic acid, and the reaction time on the oxirane oxygen content (OOC) of the epoxidised jatropha oil (EJO) were investigated. It was found that 4.3% OOC could be achieved with a molar ratio of 1:0.6, a reaction temperature of 60 °C, and 4 h of reaction. Consequently, a series of polyols with hydroxyl numbers in the range of 138-217 mgKOH/g were produced by oxirane ring opening of EJOs, and the physicochemical and rheological properties were studied. Both the EJOs and the JOLs are liquid and have a number average molecular weight (Mn) in the range of 834 to 1457 g/mol and 1349 to 2129 g/mol, respectively. The JOLs exhibited Newtonian behaviour, with a low viscosity of 430-970 mPas. Finally, the JOL with a hydroxyl number of 161 mgKOH/g was further used to synthesise aqueous polyurethane dispersion, and the urethane formation was successfully monitored by Fourier Transform Infrared (FTIR). [ABSTRACT FROM AUTHOR]

A new type of binder for wood particles or fibres was developed using a recycled polyol from polyurethane or PET wastes and a polyisocyanate as raw materials. The binders developed with various ratios of hydroxyl and isocyanate groups are solid at room temperature with melting points between 40 and 60°C. Between 5 and 20% of these were mixed with the wood products and compression-moulded at temperatures between 80 and 100°C and 0.75 to 2.05 kp/mm² pressure to give composites of tensile strength up to 47 N/mm2 or flexural strength up to 58 N/mm2.

Polyurethanes (PUs) are an important and versatile class of polymers that are applied in industry, building construction and in various consumer products. However, the rigid and complex structure of PU makes it challenging to deal with PU at end-of-life, while without appropriate waste treatment, disposed PU products may result in severe environmental pollution. Thermochemical recycling processes allow the production of valuable chemicals from PU waste streams and may enable circular recycling routes. This review focuses on pyrolysis of PUs studied by thermogravimetric methods as well as on experiments conducted in micro or bench-scale lab reactors, that allow to study the product distribution and the thermal decomposition chemistry relevant for pyrolysis and gasification processes. PUs typically decompose in multiple stages as function of the temperature, whereby generally the isocyanate linkers disassociate at lower temperatures and the high molecular weight polyol linkers decompose at higher temperatures. The product distributions were found to strongly depend on the composition of PU and the pyrolysis conditions, while the presence of fire retardants and other additives did hardly have an effect. By further development and optimization, it is expected that pyrolysis and gasification can be suitable alternatives to deal with growing amounts of PU waste. • PU Pyrolysis is the most studied process for chemical recycling of waste plastics in academia but mostly at lab scale. • Scale up of PU pyrolysis processes has been hindered by the need for an extensive separation train for purification. • Gasification processes of mixed waste containing PU is promising. • The investment costs for PU gasification plants are high, and only feasible at scales (≥500 kt/a). [ABSTRACT FROM AUTHOR]