Open-Cell Spray Polyurethane Foams Based on Biopolyols from Fruit Seed Oils

Natural oils from watermelon, cherry, black currant, grape and pomegranate fruit seeds were applied in the synthesis of biopolyols using the transesterification reaction. In this manuscript, the preparation possibility of open-cell foams from a polyurethane system in which petrochemical polyol was fully replaced with biopolyols is analyzed. Firstly, polyurethane foam systems were developed on a laboratory scale, and they were next tested under industrial conditions. It was shown that the foaming method has a significant impact on the foaming process and the cell structure of obtained foams as well as their thermal insulation properties. Based on the conducted research, it was found that the method of processing the polyurethane system has a significant impact on the properties of open-cell spray foams. Foams produced under industrial conditions have a much higher cell density, which has a positive effect on their selected physical-mechanical properties compared to foams produced on a laboratory scale. The open-cell biofoams obtained using a high-pressure machine had apparent densities 12-17 kg/m3, thermal conductivity coefficients 35-37 mW/m·K, closed-cell contents < 10% and were dimensionally stable at low and high temperatures.

Eco-Friendly Cork-Polyurethane Biocomposites for Enhanced Impact Performance: Experimental and Numerical Analysis

Cork composites are byproducts from wine stopper production, resulting from the agglomeration of cork granules with a thermoset resin. The resulting compound is a versatile and durable material with numerous industrial applications. Due to its unique properties, such as low-density, high-strength, excellent energy absorption, and good thermal and acoustic insulators, cork composites find room for application in demanding industries such as automotive, construction, and aerospace. However, agglomerated cork typically has a polyurethane matrix derived from petrochemical sources. This study focuses on developing eco-friendly porous polyurethane biocomposites manufactured with the used cooking oil polyol modified with cork. Since cork and polyurethane foam are typically used for impact shock absorption, the manufactured samples were subjected to impact loading. The assessment of crashworthiness is performed through 100 J impact tests. A finite element numerical model was developed to simulate the compression of these new composites under impact, and the model validation was performed. The highest specific absorbed energy was obtained for petrochemical polyol composites with the 3% addition of natural or modified cork. The research conducted in this study showcased the feasibility of substituting certain petrochemical components used for the synthesis of the polyurethane matrix with ecological waste vegetable oil components.

Application of Modified Seed Oils of Selected Fruits in the Synthesis of Polyurethane Thermal Insulating Materials

The use of alternative raw material sources in polyurethane chemistry is necessary given the limited supply of fossil fuels, their rising prices and the concern for sustainability. The production of biopolyols from edible vegetable oils such as rapeseed oil, soybean oil or sunflower oil is often proposed. In order to avoid conflict with the global food economy, non-edible or waste oils are hoped to find application in chemical synthesis. The possibility of using oils from selected fruit seeds to obtain biopolyols is analyzed in this manuscript. Five biopolyols were obtained from watermelon, cherry, black currant, grape and pomegranate fruit seeds using the transesterification reaction of the oils with triethanolamine. Thermal insulating polyurethane foams were then obtained by replacing 75% of petrochemical polyol with the biopolyols in polyurethane systems. Based on an analysis of the foaming process, it was found that the incorporation of triethanolamine molecules into the biopolyols causes a catalytic effect. The use of such biopolyols allows eliminating the catalyst from a polyurethane foam formulation. The polyurethane biofoams obtained with the pomegranate-seed-based biopolyol were characterized by the highest content of closed cells (45 vol.%). The lowest content was found for the foams containing the currant-seed-based biopolyol (9%). The foams were characterized by thermal conductivity coefficients between 32 and 35 kW/m·K and densities of approximately 40 kg/m3. Good dimensional stability and compressive strength between 100 and 250 kPa make them suitable for use in construction.

From Bioresources to Thermal Insulation Materials: Synthesis and Properties of Two-Component Open-Cell Spray Polyurethane Foams Based on Bio-Polyols from Used Cooking Oil

Open-cell spray polyurethane foams are widely used as highly efficient thermal insulation materials with vapor permeability and soundproofing properties. Unfortunately, for the production of commercial foams, mainly non-renewable petrochemical raw materials are used. The aim of this study was to determine the possibility of completely replacing petrochemical polyols (the main raw material used in the synthesis of polyurethanes, alongside isocyanates) with bio-polyols obtained from used cooking oils, classified as waste materials. The research consisted of three stages: the synthesis of bio-polyols, the development of polyurethane foam systems under laboratory conditions, and the testing of developed polyurethane spray systems under industrial conditions. The synthesis of the bio-polyols was carried out by using two different methods: a one-step transesterification process using triethanolamine and a two-step process of epoxidation and opening oxirane rings with diethylene glycol. The obtained bio-polyols were analyzed using gel chromatography and nuclear magnetic resonance spectroscopy. The developed polyurethane foam formulations included two types of fire retardants: halogenated tris(1-chloro-2-propyl) phosphate (TCPP) and halogen-free triethyl phosphate (TEP). In the formulations of polyurethane systems, reactive amine catalysts were employed, which become incorporated into the polymer matrix during foaming, significantly reducing their emission after application. The foams were manufactured on both a laboratory and industrial scale using high-pressure spray machines under conditions recommended by commercial system manufacturers: spray pressure 80-100 bar, component temperature 45-52 °C, and component volumetric ratio 1:1. The open-cell foams had apparent densities 14-21.5 kg/m3, thermal conductivity coefficients 35-38 mW/m∙K, closed-cell contents <5%, water vapor diffusion resistance factors (μ) <6, and limiting oxygen indexes 21.3-21.5%. The properties of the obtained foams were comparable to commercial materials. The developed polyurethane spray systems can be used as thermal insulation materials for insulating interior walls, attics, and ceilings.

Effect of Selected Bio-Components on the Cell Structure and Properties of Rigid Polyurethane Foams

New rigid polyurethane foams (RPURFs) modified with two types of bio-polyols based on rapeseed oil were elaborated and characterized. The effect of the bio-polyols with different functionality, synthesized by the epoxidation and oxirane ring-opening method, on the cell structure and selected properties of modified foams was evaluated. As oxirane ring-opening agents, 1-hexanol and 1.6-hexanediol were used to obtain bio-polyols with different functionality and hydroxyl numbers. Bio-polyols in different ratios were used to modify the polyurethane (PUR) composition, replacing 40 wt.% petrochemical polyol. The mass ratio of the used bio-polyols (1:0, 3:1, 1:1, 1:3, 0:1) affected the course of the foaming process of the PUR composition as well as the cellular structure and the physical and mechanical properties of the obtained foams. In general, the modification of the reference PUR system with the applied bio-polyols improved the cellular structure of the foam, reducing the size of the cells. Replacing the petrochemical polyol with the bio-polyols did not cause major differences in the apparent density (40-43 kg/m3), closed-cell content (87-89%), thermal conductivity (25-26 mW⋅(m⋅K)-1), brittleness (4.7-7.5%), or dimensional stability (<0.7%) of RPURFs. The compressive strength at 10% deformation was in the range of 190-260 and 120-190 kPa, respectively, for directions parallel and perpendicular to the direction of foam growth. DMA analysis confirmed that an increase in the bio-polyol of low functionality in the bio-polyol mixture reduced the compressive strength of the modified foams.

Cork Porous Biocomposites with Polyurethane Matrix Modified with Polyol Based on Used Cooking Oil

Renewable materials are materials that are replenished naturally and can be used again and again. These materials include things such as bamboo, cork, hemp, and recycled plastic. The use of renewable components helps to reduce the dependence on petrochemical resources and reduce waste. Adopting these materials in various industries such as construction, packaging, and textiles can lead to a more sustainable future and decrease the carbon footprint. The presented research describes new porous polyurethane biocomposites based on used cooking oil polyol (50 per hundred polyol-php) modified with cork (3, 6, 9, and 12 php). The research described here demonstrated that it is possible to replace some petrochemical raw materials with raw materials of renewable origin. This was achieved by replacing one of the petrochemical components used for the synthesis of the polyurethane matrix with a waste vegetable oil component. The modified foams were analyzed in terms of their apparent density, coefficient of thermal conductivity, compressive strength at 10% of deformation, brittleness, short-term water absorption, thermal stability, and water vapor permeability, while their morphology was examined using scanning electron microscopy and the content of closed cells. After the successful introduction of a bio-filler, it was found that the thermal insulation properties of the modified biomaterials were comparable to those of the reference material. It was concluded that it is possible to replace some petrochemical raw materials with raw materials of renewable origin.

Hemp Seed Oil and Oilseed Radish Oil as New Sources of Raw Materials for the Synthesis of Bio-Polyols for Open-Cell Polyurethane Foams

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.

Impact of Various Catalysts on Transesterification of Used Cooking Oil and Foaming Processes of Polyurethane Systems

The search for new sources of raw materials that can be used in the synthesis of polyurethanes and other polymer groups is extremely important. Currently, according to the principles of green chemistry and a circular economy, waste materials with a high reuse potential are being sought. This article presents a way of obtaining used-cooking-oil-based compounds capable of participating in the reaction of polyurethane creation. The transesterification reaction can be carried out using a variety of homo- and heterogeneous acid or base catalysts. Here, we looked at the impact of selected catalysts on the course of transesterification reactions, the composition of the post-reaction mixture and the possibility of using the products in polyurethane foam synthesis. The raw materials and the products were analyzed by means of gel permeation chromatography, FTIR spectroscopy and ¹H NMR. The polyurethane foam formation process was analyzed using a FOAMAT^® apparatus.

The Effect of a Chemical Foaming Agent and the Isocyanate Index on the Properties of Open-Cell Polyurethane Foams

This article presents an ecological approach based on climate neutrality to the synthesis of open-cell polyurethane foams with modified used cooking rapeseed oils. Water was used as a chemical blowing agent in the amount of 20-28 wt.% in relation to the weight of the bio-polyol. The influence of water on the physical and mechanical properties of the synthesized foams was investigated. The resultant porous materials were tested for the content of closed cells, cell structure, apparent density, thermal conductivity, compressive strength, and dimensional stability. It was found that the apparent density decreased in the range of 11-13 kg/m³ when the amount of the foaming agent was increased. In the next step, a foam with a water content of 22% was selected as having the most favorable physico-mechanical properties among all the foams with various water contents. The isocyanate index of the selected foam was then changed from 0.6 to 1.1 and it was observed that the compressive strength increased by an average of 10 kPa. The thermal conductivity coefficients of the final materials with different water contents and isocyanate indices were comparable and in the range of 40-43 mW/m·K.

Scale-Up and Testing of Polyurethane Bio-Foams as Potential Cryogenic Insulation Materials

This article compares the properties of closed-cell PUR bio-foams produced on a laboratory scale and on an industrial scale. In the formulation used, the polyol premix contained 40 wt.% of a bio-polyol based on rapeseed oil. Selected useful properties of the foams obtained on the two scales and the use of one-step and spraying methods were compared. In the case of the spraying method, the experimental system was compared to a commercial one. Given the possibility of applying the bio-foams in insulation systems for cryogenic and liquefied natural gas (LNG) applications, a compressive strength analysis of the foams was carried out at room temperature as well as at −196 °C. It was found that the foams modified with the bio-polyol were characterized by a higher compressive strength at low temperatures than commercial foams based on a petrochemical polyol.

Rigid Polyurethane Foams Modified with Biochar

This paper presents results of research on the preparation of biochar-modified rigid polyurethane foams that could be successfully used as thermal insulation materials. The biochar was introduced into polyurethane systems in an amount of up to 20 wt.%. As a result, foam cells became elongated in the direction of foam growth and their cross-sectional areas decreased. The filler-containing systems exhibited a reduction in their apparent densities of up to 20% compared to the unfilled system while maintaining a thermal conductivity of 25 mW/m·K. Biochar in rigid polyurethane foams improved their dimensional and thermal stability.

Bio-Polyurethane Foams Modified with a Mixture of Bio-Polyols of Different Chemical Structures

We report on rigid polyurethane (PUR) foams prepared using different contents of a mixture of two bio-polyols (20–40 php). The bio-polyols were obtained through epoxidation and a ring opening reaction. Different chemical structures of the bio-polyols resulted from the use of 1-hexanol and 1,6-hexanediol as opening agents. The bio-polyols were characterized by hydroxyl values of 104 and 250 mgKOH/g and viscosities of 643 and 5128 mPa·s, respectively. Next, the influence of the bio-polyols on the foaming process of PUR systems as well as the foam properties was evaluated. The bio-foams modified with different contents of the bio-polyols were next compared with a reference foam obtained using a polyether petrochemical polyol. The effect of the apparent density reduction as a result of replacing the petrochemical polyol was minimized by decreasing the water content in the formulation. It was found that the modification of the recipe by changing the content of water, acting as a chemical foaming agent, did not affect the foaming process. However, the introduction of the bio-polyols mixture limited the reactivity of the systems by reducing the maximum temperature of the foaming process. The bio-materials with comparable apparent densities to that of the reference material were characterized by similar values of the thermal conductivity coefficient and a decrease in their mechanical strengths. A deterioration of mechanical properties was caused by the plasticization of the polyurethane matrices with the bio-polyols containing dangling chains. However, all materials were dimensionally stable at room temperature.

Effect of the Addition of Biobased Polyols on the Thermal Stability and Flame Retardancy of Polyurethane and Poly(urea)urethane Elastomers

Due to the current trends in sustainable development and the reduction in the use of fossil fuels (Green Deal strategy and the circular economy), and thus, the increased interest of the polyurethane industry in polyols derived from renewable sources, it is important to study the impact of these polyols on the flammability of new bioelastomers. The goal of this study was to check the influence of biobased polyols, such as tall oil (TO)-based polyols, soybean oil (SO)-based polyol, and rapeseed oil (RO)-based polyol, on the reduction in the burning and fume emissions of polyurethane and poly(urea)urethane elastomers (EPURs and EPUURs). The thermal stability of these materials was tested using thermogravimetric analysis (TGA). In turn, the flame retardancy and smoke emissions were checked using a cone calorimetry test. The released gases were identified using TGA coupled with Fourier transform infrared (FT-IR) spectroscopy (TGA/FT-IR). Moreover, the morphological and structural characteristics of the char residues were characterized using FT-IR and scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS). The obtained data were compared to the results received for elastomers produced with petroleum substrates. The addition of biobased polyols led to a reduction in the burning as a result of the formation of char, especially RO polyol. Moreover, the TO and RO polyols increased the thermal stability of the elastomers.