Project description:High-quality rigid polyurethane (PU) foam thermal insulation material has been developed solely using bio-polyols synthesized from second-generation bio-based feedstock. High functionality bio-polyols were synthesized from cellulose production side stream-tall oil fatty acids by oxirane ring-opening as well as esterification reactions with different polyfunctional alcohols, such as diethylene glycol, trimethylolpropane, triethanolamine, and diethanolamine. Four different high functionality bio-polyols were combined with bio-polyol obtained from tall oil esterification with triethanolamine to develop rigid PU foam formulations applicable as thermal insulation material. The developed formulations were optimized using response surface modeling to find optimal bio-polyol and physical blowing agent: c-pentane content. The optimized bio-based rigid PU foam formulations delivered comparable thermal insulation properties to the petro-chemical alternative.
Project description:Bio-polyols (BPOs), characterized by a hydroxyl number up to around 90 mg KOH/g, narrow polydispersity index and relatively low molecular mass up to 2000 g/mol, were synthetized from partially and completely epoxidized soybean and linseed oils and caprylic acid or 3-phenyl butyric acid. These BPOs were used in the presence of toluene diisocyanate to produce polyurethane (PU) foams by using a quasi-prepolymer method involving a two-step reaction. A detailed structural investigation of the prepolymers from toluene diisocyanate and both BPOs and polypropylene glycol was conducted by SEC and solution NMR. The apparent density of the foams was in the range of 40-90 kg/m3, with higher values for foams from the aromatic acid. All the foams showed an open-cell structure with uniform and regular shape and uniform size. The specific Young's moduli and compression deflection values suggest superior mechanical properties than the reference foams. The novel synthesized polyurethanes are excellent candidates to partially replace petroleum-based materials.
Project description:Developing polyols derived from natural sources and recycling materials attracts great interest for use in replacing petroleum-based polyols in polyurethane production. In this study, rigid polyurethane (PUR) foams with various isocyanate indices were obtained from polyols based on rapeseed oil and polyethylene terephthalate (RO/PET). The various properties of the prepared PUR foams were investigated, and the effect of the isocyanate index was evaluated. The closed-cell content and water absorption were not impacted by the change of the isocyanate index. The most significant effect of increasing the isocyanate index was on the dimensional stability of the resulting foams. This is due to the increased crosslink density, as evidenced by the increased formation of isocyanurate and increase of the glass transition temperature. Additionally, the influence on compression strength, modulus, and long-term thermal conductivity were evaluated and compared with reference PUR foams from commercially available polyols. Rigid PUR foams from RO/PET polyol were found to be competitive with reference materials and could be used as thermal insulation material.
Project description:Sucrose-1,6-hexamethylene diisocyanate (HDI) cooligomers were synthesized and used as new polyols for poly(ε-caprolactone) (PCL)-based polyurethanes. The polyaddition reaction of sucrose and HDI was monitored by MALDI-TOF MS. It was found that by selecting appropriate reaction conditions, mostly linear oligomer chains containing 16 sucrose units could be obtained. For the synthesis of polyurethane networks, prepolymers were prepared by the reaction of poly(ε-caprolactone) (PCL, 10 kg/mol) with HDI or 4,4'-methylene diphenyl diisocyanate (MDI) and were reacted with sucrose-HDI cooligomers. The so-obtained sucrose-containing polyurethanes were characterized by means of attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FT IR), swelling, mechanical (uniaxial tensile tests) and differential scanning calorimetry (DSC).
Project description:The utilization of polyols derived from renewable sources presents an opportunity to enhance the sustainability of rigid polyurethane (PUR) foams, thereby contributing to the advancement of a circular bioeconomy. This study explores the development of PUR rigid foams exclusively using polyols sourced from second-generation renewable biomass feedstocks, specifically depolymerized birch bark suberin (suberinic acids) and tall oil fatty acids. The polyols achieved a total renewable material content as high as 74%, with a suberinic acid content of 37%. Response surface modeling was employed to determine the optimal bio-polyol, blowing agents, and catalyst content, hence, optimizing the bio-based foam formulations. In addition, response surface modeling was applied to rigid PUR foam formulations based on commercially available petroleum-based polyols for comparison. The results, including apparent density (~40-44 kg/m3), closed cell content (~95%), compression strength (>0.2 MPa, parallel to the foaming direction), and thermal conductivity (~0.019 W/(m·K)), demonstrated that the suberinic acids-based rigid PUR foam exhibited competitive qualities in comparison to petroleum-based polyols. Remarkably, the bio-based rigid PUR foams comprised up to 29% renewable materials. These findings highlight the potential of suberinic acid-tall oil polyols as effective candidates for developing rigid PUR foams, offering promising solutions for sustainable insulation applications.
Project description:The trend towards the utilization of bioresources for the manufacturing of polymers has led industry players to bring to the market new monomers. In this work, we studied 3 polyisocyanates and 2 polyols with high renewable carbon contents, namely L-lysine ethyl ester diisocyanate (LDI), pentamethylene-diisocyanate (PDI) isocyanurate trimer, and hexamethylene-diisocyanate (HDI) allophanate as the isocyanates, as well as castor oil and polypropanediol as the polyols. These monomers are commercially available at a large scale and were used in direct formulations or used as prepolymers. Thermosetting polymers with Tg values ranging from -41 to +21 °C and thermal stabilities of up to 300 °C were obtained, and the polymerization was studied using NMR, DSC, and rheology. Cured materials were also characterized using FTIR, DMA, gel content, and swelling index determinations. These high bio-based content materials can successfully be obtained and could be used as alternatives to petro-based materials.
Project description:We report the fabrication of bio-based thermoplastic polyurethane (TPU) fibrous scaffolds containing essential oils (EO). The main goal of this study was to investigate the effects of essential oil type (St. John's Wort oil (SJWO), lavender oil (LO), and virgin olive oil (OO))/concentration on the electrospinnability of TPU. The effects of applied voltage, flow rate, and end-tip distance on the diameter, morphology, and wettability of the TPU/EO electrospun fibers were investigated. The electrospun TPU/EO scaffolds were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), contact angle (CA), and Fourier transform infrared spectroscopy (FTIR). The addition of oil resulted in an increase in the fiber diameter, reduction in the surface roughness, and, accordingly, a reduction in the contact angle of the composite fibers. TPU fibers containing SJWO and LO have a more flexible structure compared to the fibers containing OO. This comparative study fills the existing information gap and shows the benefits of the fabrication of essential-oil-incorporated electrospun fiber with morphology and size range with respect to the desired applications, which are mostly wound dressing and food packaging.
Project description:The article compares the properties of bio-polyols obtained from white mustard (Sinapis alba) seed oil, which contain boron and sulfur atoms. Each of the bio-polyols was prepared by a different method of testing the efficiency of the incorporation of boron and sulfur atoms. All synthesis methods were based on the epoxidation of unsaturated bonds followed by the opening of epoxy rings by compounds containing heteroatoms. Two of the bio-polyols were subjected to additional esterification reactions of hydroxyl groups with boric acid or its ester. Three new bio-polyols were obtained as a result of the performed syntheses. The synthesized compounds were subjected to detailed physicochemical (physical state, color, smell, density, viscosity and pH), analytical (hydroxyl number, acid number, water content, content of C, H, N, S, O, B elements and GPC analysis), spectroscopic (FTIR, 1H NMR and 13C NMR) and thermal (DSC) tests. The obtained results allowed for a detailed characterization of the synthesized bio-polyol raw materials. Their suitability for obtaining polyurethane materials was also determined. The synthesized compounds have been found to be an interesting alternative to petrochemical polyols. The influence of the synthesized compounds on the flammability of polyurethane materials was tested experimentally. On the basis of this testing, a number of rigid polyurethane/polyisocyanurate foams were obtained, which were then subjected to flammability tests with the methods of horizontal and vertical burning, limiting oxygen index (LOI) and using the cone calorimeter. Based on this research, it was found that the presence of sulfur and boron heteroatoms reduced the flammability of polyurethane materials based on synthesized bio-polyols.
Project description:Lignin-based polyols were synthesized through microwave-assisted liquefaction under different microwave heating times (5-30 min). The liquefaction reactions were carried out using polyethylene glycol (PEG-400)/glycerol as liquefying solvents and 97 wt% sulfur acid as a catalyst at 140 °C. The polyols obtained were analyzed for their yield, composition and structural characteristics using gel permeation chromatography (GPC), Fourier transform infrared (FT-IR) and nuclear magnetic resonance (NMR) spectra. FT-IR and NMR spectra showed that the liquefying solvents reacted with the phenol hydroxyl groups of the lignin in the liquefied product. With increasing microwave heating time, the viscosity of polyols was slightly increased and their corresponding molecular weight (MW) was gradually reduced. The optimal condition at the microwave heating time (5 min) ensured a high liquefaction yield (97.47%) and polyol with a suitable hydroxyl number (8.628 mmol/g). Polyurethane (PU) foams were prepared by polyols and methylene diphenylene diisocyanate (MDI) using the one-shot method. With the isocyanate/hydroxyl group ([NCO]/[OH]) ratio increasing from 0.6 to 1.0, their mechanical properties were gradually increased. This study provided some insight into the microwave-assisted liquefied lignin polyols for the production of rigid PU foam.
Project description:The use of an appropriate oleogelator in the structuring of vegetable oil is a crucial point of consideration. Sunflower wax (SFW) is used as an oleogelator and displays an excellent potential to bind vegetable oils. The current study aimed to look for the effects of hydrophobic (SPAN-80) and hydrophilic (TWEEN-80) emulsifiers on the oleogels prepared using SFW and sunflower oil (SO). The biodegradability and all formulations showed globular crystals on their surface that varied in size and number. Wax ester, being the most abundant component of SFW, was found to produce fibrous and needle-like entanglements capable of binding more than 99% of SO. The formulations containing 3 mg of liquid emulsifiers in 20 g of oleogels showed better mechanical properties such as spreadability and lower firmness than the other tested concentrations. Although the FTIR spectra of all the formulations were similar, which indicated not much variation in the molecular interactions, XRD diffractograms confirmed the presence of β' form of fat crystals. Further, the mentioned formulations also showed larger average crystallite sizes, which was supported by slow gelation kinetics. A characteristic melting point (Tm~60 °C) of triglyceride was visualized through DSC thermograms. However, a higher melting point in the case of few formulations suggests the possibility of even a stable β polymorph. The formed oleogels indicated the significant contribution of diffusion for curcumin release. Altogether, the use of SFW and SO oleogels with modified properties using biodegradable emulsifiers can be beneficial in replacing saturated fats and fat-derived products.