Rigid Polyurethane-polyisocyanurate Foams Research Articles

Polyurethane‐polyisocyanurate (PUR‐PIR) foams based on castor oil modified with tire rubber waste: Statistical‐based analysis

AbstractThis study explores the utilization of bio‐polyol, derived from castor oil modified with waste tire rubber (WTR), in the synthesis of rigid polyurethane–polyisocyanurate foams. Two WTR concentrations (10% and 20%) were incorporated, investigating their impact on foaming, cellular structure, and various foam properties. Response surface methodology assessed the influence of polyol/isocyanate ratios and WTR content on thermal, physical, and mechanical responses. Results indicated significant effects of polyol/isocyanate ratios on thermal and density properties, while WTR content exhibited an opposite trend. Mechanical behavior showed a distinct pattern compared to thermal and physical aspects, suggesting no conclusive correlation between compressive stress variability and polyol/isocyanate ratio or WTR content. Consequently, the application of these foams depends on specific property requirements, highlighting the potential of sustainable bio‐polyols and recycled WTR in replacing conventional petroleum‐based counterparts in polyurethane foam production.Highlights Development of rigid polyurethane–polyisocyanurate foams based on castor oil. Polyurethane–polyisocyanurate foams modified with waste tire rubber. Increased isocyanate index impacts thermal stability and density. Response surface methodology showed variability in compressive stress behavior and the polyol/isocyanate ratio. For application of polyurethane–polyisocyanurate foams will depend on the desired properties.

Methods to Increase or Decrease Resistance to Photodegradation and Biodegradation of Polyurethane/Polyisocyanurate (PU/PIR) Foams.

Two series of rigid polyurethane-polyisocyanurate (PU/PIR) foams were obtained. They were modified using powder fillers, such as industrial food cocoa (K5-K15 foam) and instant freeze-dried coffee (KR-KR15) added in amounts of 5, 10 and 15 wt.%. W foam (reference) was obtained without filler. The foams were degraded in a climate chamber for 1 week, 2 weeks or 3 weeks. Appropriate temperature, humidity and UV radiation were set in the chamber, which did not change throughout the degradation process. The foams were also degraded in an oven for two days at 120 °C. The foam tests carried out indicated, among others, on the decrease in compressive strength along with the increase in the residence time of the samples in the chamber. Degraded foams also changed color. Foams containing 5% and 10% of industrial cocoa or freeze-dried coffee were more susceptible to degradation. The addition of 15% coffee or cocoa slows down the degradation process. In the present study, industrial food cocoa and instant freeze-dried coffee were used as modifiers of rigid PU/PIR foam. These fillers have two functions: they accelerate the biodegradation of foams and have antioxidant properties.

Study on the Structure-Property Dependences of Rigid PUR-PIR Foams Obtained from Marine Biomass-Based Biopolyol.

The paper describes the preparation and characterization of rigid polyurethane-polyisocyanurate (PUR-PIR) foams obtained with biopolyol synthesized in the process of liquefaction of biomass from the Baltic Sea. The obtained foams differed in the content of biopolyol in polyol mixture (0–30 wt%) and the isocyanate index (IISO = 200, 250, and 300). The prepared foams were characterized in terms of processing parameters (processing times, synthesis temperature), physical (sol fraction content, apparent density) and chemical structure (Fourier transform infrared spectroscopy), microstructure (computer microtomography), as well as mechanical (compressive strength, dynamic mechanical analysis), and thermal properties (thermogravimetric analysis, thermal conductivity coefficient). The influence of biopolyol and IISO content on the above properties was determined. The addition of up to 30 wt% of biopolyol increased the reactivity of the polyol mixture, and the obtained foams showed enhanced mechanical, thermal, and insulating properties compared to foams prepared solely with petrochemical polyol. The addition of up to 30 wt% of biopolyol did not significantly affect the chemical structure and average cell size. With the increase in IISO, a slight decrease in processing times and mechanical properties was observed. As expected, foams with higher IISO exhibited a higher relative concentration of polyisocyanurate groups in their chemical structure, which was confirmed using principal component analysis (PCA).

Assessment of Photodegradation and Biodegradation of RPU/PIR Foams Modified by Natural Compounds of Plant Origin.

Four types of rigid polyurethane-polyisocyanurate foams (RPU/PIR) were obtained. Three of them were modified by powder fillers, such as cinnamon extract (C10 foam), green coffe extract (KZ10), and cocoa extract (EK10) in an amount of 10 wt %. The last foam was obtained without a filler (W foam). The basic properties and thermal properties of obtained foams were examined. All foams were subjected to degradation in the climatic chamber acting on samples of foams in a defined temperature, humidity, and UV radiation for 7, 14, and 21 days. The physico-mechanical properties of foams were tested. The compressive strength of degraded foams after 7, 14, and 21 days was compared with the compressive strength of nondegraded foams (0 days). The chosen properties of degraded foams, such as cellular structure by scanning electron microscopy (SEM) and changes of chemical structure by FTIR spectroscopy were compared. The obtained foams were also subjected to degradation in a circulating air dryer in an increased temperature (120 °C) for 48 h. Additionally, W, C10, ZK10, EK10 foams were placed in a soil environment and subjected to 28 days biodegradation process. The biochemical oxygen demand (BOD), the theoretical oxygen demand (TOD), and the degree of biodegradation (Dt) of foams were determined in this measurment. Test results showed that the compressive strength of foams decreased with the longer time of foam degradation in the conditioner. The foam subjected to degradation darkened and became more red and yellow in color. The addition of natural compounds of plant origin to foams increased their susceptibility to biodegradation.

The Use of Waste from the Production of Rapeseed Oil for Obtaining of New Polyurethane Composites

This article presents the results of research on obtaining new polyurethane materials modified by a by-product from vegetable oils industry—rapeseed cake. The chemical composition of rapeseed cake was examined. Rigid polyurethane-polyisocyanurate (RPU/PIR) foams containing a milled rapeseed cake in their composition were obtained as part of the conducted research. Biofiller was added in amount of 30 wt.% up to 60 wt.%. Effects of rapeseed cake on the foaming process, cell structure and selected properties of foams, such as apparent density, compressive strength, brittleness, flammability, absorbability, water absorption, thermal resistance and thermal conductivity are described. The foaming process of RPU/PIR foams modified by rapeseed cake was characterized by a lower reactivity, lower foaming temperature and decrease in dielectric polarization. This resulted in a slowed formation of the polyurethane matrix. Apparent density of RPU/PIR foams with biofiller was higher than in unmodified foam. Addition of rapeseed cake did not have a significant influence on the thermal conductivity of obtained materials. However, we observed a tendency for opening the cells of modified foams and obtaining a smaller cross-sectional area of cells. This led to an increase of absorbability and water absorption of obtained materials. However, an advantageous effect of using rapeseed cake in polyurethane formulations was noted. Modified RPU/PIR foams had higher compressive strength, lower brittleness and lower flammability than reference foam.

Rigid polyurethane–polyisocyanurate foams modified with grain fraction of fly ashes

This article describes the results of multidirectional research on producing new polyurethane materials modified with grain fraction of fly ashes. As a result of the conducted research, new polyurethane–polyisocyanurate foams were produced, which contained 5% to 35% of a microsphere in relation to its mass. Examinations on mechanical and thermal properties, as well as flammability, were conducted. The increasing content of aluminosilicate microspheres in rigid polyurethane–polyisocyanurate foams increased the apparent density of these materials. Based on the results, it was determined that the use of the microsphere in the recipe for producing polyurethane–polyisocyanurate foams is very advantageous. The obtained rigid foams are characterized by lower brittleness, higher compressive strength, higher closed cell count, as well as significantly lower flammability in relation to the reference foam (not modified with the filler).

The Effect of Accelerated Aging Conditions on the Properties of Rigid Polyurethane-Polyisocyanurate Foams Modified by Cinnamon Extract

Two series of rigid polyurethane-polyisocyanurate foams (RPU/PIR) modified by cinnamon extract (series C_0t and CU_0t) were obtained. One RPU/PIR series contained a commercial flame retardant (C_0t) in the formulation. The other was produced without its participation (CU_0t). The basic properties of obtained foams, e.g., apparent density, brittleness, water absorption, compressive strength, flammability were examined. Afterwards, both series of foams (C_0t and CU_0t) were subjected to degradation in the climatic chamber, acting on samples of foams a defined temperature, humidity and UV radiation for a seven days. In this way, two successive series of RPU/PIR foams were obtained, which were designated, respectively, C_1t and CU_1t, Chosen properties of degraded foams such as: compressive strength, cellular structure by scanning electron microscopy (SEM) and changes of chemical structure by FTIR spectroscopy were determined. Compressive strength and the aging resistance was also determined (against the coefficient of compressive strength variation (CV). The possible replacement of a commercial flame retardant in polyurethane formulations by the antioxidant raw material (cinnamon extract) was evaluated.

New Poly(lactide-urethane-isocyanurate) Foams Based on Bio-Polylactide Waste.

The article presents the results of research on the synthesis of a new eco-polyol based on polylactide (PLA) waste and its use for the production of rigid polyurethane-polyisocyanurate (RPU/PIR) foams. The obtained recycling-based polyol was subjected to analytical, physicochemical and spectroscopic tests (FTIR, 1H NMR, 13C NMR) to confirm its suitability for the synthesis of polyurethane materials. Then, it was used to partially replace petrochemical polyol in polyurethane formulation. The obtained RPU/PIR foams were characterized by lower apparent density, brittleness, and water absorption. In addition, foams modified by eco-polyol had higher flame retardancy, as compared to reference foam. The results of the research show that the use of PLA polyol based on plastic waste may be an alternative to petrochemical polyols. This research matches with the current trends of sustainable development and green chemistry.

Effect of Evening Primrose Oil-Based Polyol on the Properties of Rigid Polyurethane⁻Polyisocyanurate Foams for Thermal Insulation.

The article presents the results of research on the synthesis of a new biopolyol based on evening primrose oil, and its use in the production of rigid polyurethane–polyisocyanurate foams intended for thermal insulation. The obtained biopolyol was subjected to analytical, physicochemical, and spectroscopic tests (Fourier transform infrared (FTIR), 1H NMR, 13C NMR) to confirm its suitability for the synthesis of polyurethane materials. Then, it was used for the partial replacement of the petrochemical polyol in the polyurethane formulation. Obtained rigid polyurethane–polyisocyanurate foams are characterized by a lower apparent density, brittleness, water absorption, and thermal conductivity coefficient λ. In addition, foams modified by biopolyols had a higher content of closed cells and higher aging resistance. The results of the conducted research showed that the use of the biopolyol based on evening primrose oil may be an alternative to petrochemical polyols. The research presented herein is perfectly consistent with the trends of sustainable development and the philosophy of green chemistry.

Oenothera biennis seed oil as an alternative raw material for production of bio-polyol for rigid polyurethane-polyisocyanurate foams

The aim of this article is to discuss a process of obtaining a new bio-polyol based on an oil from Oenothera biennis seeds and 2,2′-mercaptodiethanol (2,2′-MDE) and its use for rigid polyurethane-polyisocyanurate (PUR-PIR) foams. The synthesis of the polyol was carried out with a two-step method. Firstly, the double bonds of unsaturated fatty acid residues were oxidized and subsequently the epoxide rings were opened by 2,2′-MDE. The properties of the obtained bio-polyol were examined for its use as a raw material for rigid polyurethane-polyisocyanurate foams, i.e. hydroxyl value, acid value, density, viscosity, pH, water content. Spectroscopic studies (FTIR, 1H NMR and 13C NMR) were also performed. Aforementioned studies confirmed the assumed chemical structure of the new polyol. The formulations of rigid foams containing from 0 to 0.3 mass equivalents of the new bio-polyol were arranged on the basis of obtained results. A significant impact of the new bio-polyol on functional properties of foams was noted: apparent density, compressive strength, brittleness, absorbability, water absorption and flammability. Modified foams had better functional properties than the reference foam.

Temperature stability and thermal properties of polyurethane-polyisocyanurate foams obtained using products of citric acid condensation

Three products were obtained from the condensation of citric acid with: propane-1,2-diol with the catalyst Tyzor TPT (HDCA1), propane-1,2-diol without a catalyst (HDCA2) and ­propane-1,3-diol with the catalyst Tyzor TPT (HDCA3). We measured the viscosities (from 3972 mPa • s for HDCA1 to 27 986 mPa • s for HDCA3), densities (about 1200 g/cm3), hydroxyl values (280–427 mg KOH/g), and acid values (­23–52 mg KOH/g) of the HDCAs. The thermal resistance of the HDCAs were assessed under dynamic conditions. The temperature ranges of 5, 10, 20 and 50 % weight loss for HDCA polyols were, respectively: 174–194 °C, 230–234 °C, 263–303 °C, and 314–364 °C. The HDCAs were used in the further synthesis of rigid polyurethane-polyisocyanurate foams (PUR-PIR) and their physical qualities assessed with reference to foams produced from an industrial standard (Rokopol RF551). The authors examined the thermal properties (thermogravimetry, differential thermogravimetry and differential scanning calorimetry) of the foams, as well as the thermal stability: dimensional, volume and mass. The number of foam degradation stages was determined, as well as the speed of degradation of specific chemical bonds and percentage mass loss during all stages. We determined the temperature of the foam’s first weight loss, the extrapolating temperature of the foam’s weight loss, the temperature of the start of the foam’s rapid decomposition, and the temperature of the foam’s highest speed of weight loss, the temperatures of 5 %, 10 %, 20 % and 50 % mass loss were measured (respectively: 208–223 °C, 230–260 °C, 280–300 °C, 345–366 °C). The enthalpy related to each individual stage of foam degradation was examined using DSC (three endotherms and one exothermic peak).

The effect of ground coffee on the mechanical and application properties of rigid polyurethane-polyisocyanurate foams (Rapid communication)

The effect of ground coffee on the mechanical and application properties of rigid polyurethane-polyisocyanurate foams (Rapid communication)

Rheological properties, oxidative and thermal stability, and potential application of biopolyols prepared via two-step process from crude glycerol

In this work, previously synthesized biopolyols were analyzed in terms of their rheological and thermal properties, very important from the technological point of view. For better evaluation of performed synthesis, the influence of its time and temperature on the properties of biopolyols was determined. In the end, obtained materials were used to prepare rigid polyurethane-polyisocyanurate (PUR-PIR) foams, to evaluate their potential application in polymer technology. Presented results fully justified conducting of synthesis in two steps. Biopolyols obtained after second step of synthesis were characterized by two times lower viscosity than polyglycerols resulting from first step. Moreover, their thermal and oxidative stability was noticeably higher and enabled their effective incorporation into manufacturing of PUR-PIR foams. Spectroscopic and microscopic analysis confirmed that foams were successfully obtained from polyglycerols and biopolyols, however, there were noticeable differences in the mechanical performance of prepared materials. Partial substitution of petrochemical polyol with polyglycerol resulted in the decrease of compressive strength, comparing to reference sample, while incorporation of biopolyols noticeable enhanced that parameter.

Zastosowanie haloizytu jako napelniacza do produkcji sztywnych pianek poliuretanowo-poliizocyjanurowych

Novel rigid polyurethane-polyisocyanurate foams (PUR-PIR) modified by addition of halloysite (DOA) were the focus of this research. The filler content was in the range of 0–20 wt % in relation to the sum of the masses of the used polyol and polyisocyanate. The thermoinsulating, mechanical and aging properties as well as the flammability of the obtained materials were investigated. It has been found that the modification of PUR-PIR system by using up to 20 wt % DOA allows to produce foams with better thermoinsulating properties, lower brittleness and water absorption compared to unmodified ones. Also, the flammability of the foams was reduced.

PUR-PIR foam produced based on poly(hydroxybutyl citrate) foamed founded with different factories

Abstract 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).

Kompozyty sztywnych pianek poliuretanowo-poliizocyjanurowych z kora debu szypulkowego

New polyurethane materials – rigid polyurethane-polyisocyanurate (PUR-PIR) foams modified with ground pedunculate oak bark were obtained. The amount of added bio-filler varied from 0 to 25 % of the sum of polyol and polyisocyanate masses. The thermal, mechanical, aging and flammable properties of the produced foams were investigated. The PUR-PIR foams modified by addition of oak bark were characterized by lower brittleness, compressive strength and water absorption than those of reference foam. The apparent density, aging properties and flammability of the modified foams were similar to those of reference foam.

Performance properties of rigid polyurethane-polyisocyanurate/brewers’ spent grain foamed composites as function of isocyanate index

AbstractIn the presented work, rigid polyurethane-polyisocyanurate (PUR-PIR) foams filled with brewers’ spent grain (BSG) were prepared. The influence of the isocyanate index (II) on its performance was investigated. Foams obtained with higher isocyanate index required a higher amount of hydrofluorocarbon physical blowing agent to provide the same apparent density of material. An increase of isocyanate index resulted in a slight decrease of cell size, which was related to the increased crosslink density due to enhanced generation of allophanate and biuret groups. Deterioration of compressive strength, from 226 to 202 kPa was observed with the rise of the isocyanate index. Dynamic mechanical analysis and swelling tests confirmed the increase of crosslink density with the increasing isocyanate index. The glass transition temperature rose from 165.7°C to 193.2°C. Fourier transform infrared (FTIR) analysis indicated an increase of the isocyanurate rings’ content in composites with a higher isocyanate index, causing noticeable enhancement of thermal stability. The onset of degradation was shifted from 196°C to 211°C.

Innovative porous polyurethane-polyisocyanurate foams based on rapeseed oil and modified with expandable graphite

Rigid polyurethane-polyisocyanurate (PUR-PIR) foams were synthesized with the use of bio-polyols based on rapeseed oil. The bio-polyols were synthesized using two distinct methods oil epoxidation followed by oxirane ring opening (ROPep) and oil transesterification with triethanolamine (ROPtr). In this study, the PUR-PIR systems based on bio-polyols ROPep and ROPtr with the isocyanate indices 150 and 250 were modified with expandable graphite (3, 6 and 9wt.%). The effects of expandable graphite on the foaming process, cellular structure and selected properties of the foams such as the apparent density, compressive strength as well as water absorbance and brittleness were described. The modification of the PUR-PIR system with EG slowed down the reaction of the polymer matrix formation. The PUR-PIR system modified with EG had a lower maximum temperature and exhibited a slower decrease of the dielectric polarization during the foaming process. The apparent density of the PUR-PIR foams with EG was higher than in the case of the unmodified foams. EG did not have any significant effect on the thermal conductivity of the materials obtained. A tendency to get a smaller average cross-sectional area of cells in the foams modified with EG was observed.

The influence of crude glycerol and castor oil-based polyol on the structure and performance of rigid polyurethane-polyisocyanurate foams

In this work, biopolyol obtained from two types of industrial crops’ processing products: crude glycerol and castor oil was used for preparation or rigid polyurethane-polyisocyanurate foams. Bio-based polyol was obtained via crude glycerol polymerization and further condensation of resulting polyglycerol with castor oil. Rigid polyurethane-polyisocyanurate foams were prepared at partial substitution (0–70wt.%) of petrochemical polyol with synthesized bio-based polyol. Influence of the biopolyol content on the chemical and cellular structure, insulation properties, static and dynamic mechanical properties, thermal degradation and fire behavior of foams was investigated. Incorporation of crude glycerol-based polyol into formulation of rigid polyurethane-polyisocyanurate foams had beneficial impact on the structure of material reducing average cell size from 372 to 275μm and increasing closed cell content from 94.0 to 95.7%. Such changes resulted in 7% decrease of thermal conductivity coefficient to 21.8mW/(mK). Mechanical performance of foams was enhanced by partial substitution of petrochemical polyol with synthesized biopolyol. Compressive strength of modified foam was more than 90% higher than for reference sample. The modifications of foams caused changes in thermal degradation pathway, nevertheless thermal stability of the reference foam was maintained. Incorporation of crude glycerol-based polyol into foams’ formulation decreased maximum value of heat release rate by 3.5%, increased char residue after combustion by 24% and reduced emission of toxic carbon monoxide during burning of foam by 35%.

Different catalysts for new polyols for rigid PUR-PIR foams

Abstract New polyols were synthesized with 2-hydroxypropane-1.2.3-tricarboxylic acid and butane-1,4-diol (1.4-BD). The synthesis was performed using different catalysts in the amount of 0.1%. Used catalyst: Tyzor TPT, tin(II) acetate, sulfuric(IV) acid. The fourth reaction was conducted without the use of a catalyst. The polyols’ properties were evaluated with regards to the usefulness in rigid polyurethane-polyisocyanurate (PUR-PIR) foams (acid value, density, pH and solubility, FTIR spectra). Based on the research, it was evaluated that only the polyol synthesized using Tyzor TPT (E6) was useful in production of rigid PUR-PIR foams. Its hydroxyl number was 496 mgKOH/g and its viscosity was about 14 552 mPa · s. A series of five foams P6.1–P6.5 was produced with this polyol. Rigid foams test results indicated that the amount of this compound in the foam substantially affects its compressive strength, density and their retention. The foams have low brittleness values.