Rigid Polyurethane-polyisocyanurate 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.

Effect of bio-polyol molecular weight on the structure and properties of polyurethane-polyisocyanurate (PUR-PIR) foams

The increasing interest in polyurethane materials has raised the question of the environmental impact of these materials. For this reason, the scientists aim to find an extremely difficult balance between new material technologies and sustainable development. This work attempts to validate the possibility of replacing petrochemical polyols with previously synthesized bio-polyols and their impact on the structure and properties of rigid polyurethane-polyisocyanurate (PUR-PIR). To date, biobased polyols were frequently used in the manufacturing of PU, but application of bio-polyols synthesized via solvothermal liquefaction using different chains of polyethylene glycol has not been comprehensively discussed. In this work, ten sets of rigid polyurethane foams were synthesized. The influence of bio-polyols addition on foam properties was investigated by mechanical testing, thermogravimetric analysis (TGA), and cone calorimetry. The structure was determined by scanning electron microscopy (SEM) and a gas pycnometer. The tests revealed a significant extension of foam growth time, which can be explained by possible steric hindrances and the presence of less reactive secondary hydroxyl groups. Moreover, an increase average size of pores and aspect ratio was noticed. This can be interpreted by the modification of the cell growth process by the introduction of a less reactive bio-polyol with different viscosity. The analysis of foams mechanical properties showed that the normalized compressive strength increased up to 40% due to incorporation of more cross-linked structures. The thermogravimetric analysis demonstrated that the addition of bio-based polyols increased temperature of 2% (T2%) and 5% (T5%) mass degradation. On the other hand, evaluation of flammability of manufactured foams showed increase of total heat release (HRR) and smoke release (TSR) what may be caused by reduction of char layer stability. These findings add substantially to our understanding of the incorporation of bio-polyols into industrial polyurethane systems and suggest the necessity of conducting further research on these materials.

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.

Identification and Evaluation of Hazardous Pyrolysates in Bio-Based Rigid Polyurethane-Polyisocyanurate Foam Smoke.

In this study, rigid polyurethane (PU) and polyisocyanurate (PIR) foam samples made from renewable material (tall oil fatty acid) based polyols were analyzed by pyrolysis gas chromatography mass spectrometry (Py-GC/MS) to obtain information about the full relative smoke content, with a focus on substance identification by their functional groups and hazardousness. The relative content of gaseous products produced during the thermal degradation was evaluated between the two samples, differenced by their assigned isocyanate (NCO) index value—150 and 300. The main thermal degradation components of the rigid PU-PIR foam were found to originate from the decomposition of isocyanate, primarily forming 4,4′-methylenedianiline, 3,3′-diaminodiphenylmethane, N-methylaniline, aniline, 4-benzylaniline and phenyl isocyanate. Hazard analysis revealed that the most common hazards were the hazards related to health: H315 (36%), H319 (28%), H335 (25%), and H302 (23%). The chemical compound with the highest relative content value—4,4′-methylenedianiline (45.3% for PU and 52.4% for PIR)—was identified to be a suspected carcinogen and mutagen. The focus of the study was identifying and evaluating the relative quantities of the produced gaseous products, examine their hazardousness, and provide information on the released thermal degradation products to form a renewable-source based rigid PU and PIR foam.

TG/DTA-FTIR as a method for analysis of tall oil based rigid polyurethane foam decomposition gaseous products in a low oxygen environment

This study is an investigation of the suitability of the thermogravimetry and differential thermal analysis method coupled with Fourier Transform Infrared spectrometry (TG/DTA-FTIR) for a thermal degradation gaseous product analysis of a rigid polyurethane-polyisocyanurate (PU-PIR) foam synthesised from high functionality tall oil fatty acids (TOFA) based polyols. The FTIR spectra of the TG-generated gaseous thermal degradation products of three PU-PIR formulations with varied high functionality TO based polyol content (45, 75 and 95 pbw) and a different tier of isocyanate (NCO) indexes (110, 150, 200, 300 and 400) for each formulation were compared to the spectra of a formulation developed using conventional raw materials. The chemical bands of known chemical compounds and unknown compounds containing specific groups for the foams were evaluated; the focus was on the maximum release rate for specific chemical compounds (CO2; –NCO; H2O; CO) to determine the temperature zone values of the main thermal degradation phases. The experiments were carried out at a low oxygen environment, providing valuable data on the trends for the excretion of specific gaseous substances from the rigid PU-PUR foam that could be released in a real fire, where organic building materials that possess a porous matrix might be present and the nature of the combustion process is predominantly heterogeneous oxidation.

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).

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.

Thermal degradation of highly crosslinked rigid PU-PIR foams based on high functionality tall oil polyol

This study presents the development and analysis of rigid polyurethane-polyisocyanurate (PU-PIR) foam synthesized from high functionality tall oil (TO) based polyols. Three PU-PIR formulations with varied high functionality TO based polyol content (45, 75 and 95 pbw) and a different tier of isocyanate (NCO) indexes (110, 150, 200, 300 and 400) for each formulation were compared to a formulation developed using conventional raw materials, mainly obtained from petrochemicals. Using the Fourier transform infrared spectral analysis (FTIR), the chemical structure of the foams was evaluated with emphasis on the characteristic PU-PIR signal ratio and isocyanurate signal peaks. The thermal properties of the PU-PIR polymer matrix were characterized using the thermogravimetric analysis (TGA) method by comparing the thermal degradation temperatures at 5%, 25% and 50% and residual masses. Technological parameters and thermal degradation results indicate that TO is a suitable renewable resource for polyol in a rigid PU-PIR foam formulation, but the results from FTIR analysis suggest that a small optimization in the foam developing process is necessary due to an increasing amount of unreacted NCO groups in samples with the NCO index above 200.

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.

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.

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.

Poliolefiny napelniane odpadami sztywnej pianki poliuretanowej i kompatybilizowane metoda pulweryzacji scinaniem w stanie stalym podczas wytlaczania

Low density polyethylene (PE-LD), high density polyethylene (PE-HD), PE-LD/PE-HD blend at aratio of 1:1, and polypropylene (PP) were filled with finely-ground waste of rigid polyurethane-polyisocyanurate (PUR-PIR) foam in an amount up to 40 wt %. The components were homogenized with two-roll-mill and then, after granulation, subjected to additional homogenization using the method of solid-state shear pulverization (so-called S3P process) during extrusion. The specimens for comparative studies were obtained by injection molding. The changes in chemical structure (using FT-IR spectroscopy), mechanical properties (tensile and impact tests), rheological properties (MFR, rotational rheometry), and thermal properties (Vicat temperature) of the investigated compositions were determined. It was found that the pulverization has afavorable effect on the characteristics of the examined systems, although the improvement is not significant and clearly depends on the type of matrix polymer and foam content.

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.

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.

Water-blown polyurethane-polyisocyanurate foams based on bio-polyols with wood fibers

In this paper rigid polyurethane-polyisocyanurate (PUR-PIR) foam andwood fiber composites were synthesized using two types of bio-polyols. The PUR-PIR systems were modified with 3 and 6wt% of wood fibers. The influence of the content of wood fibers on the cellular structure was examined with scanning electron microscopy (SEM). Thermal and mechanical properties of the composites were characterized with thermogravimetric analysis, thermal conductivity, compressive strength, and Young modulus measurements. The influence of wood fibers on flammability of PUR-PIR foams was analyzed by oxygen index and cone calorimeter tests. For the most of foams, introduction of wood fibers did not affect the change in compressive strength. Introduction ofwood fibers increased the temperature at which thermal degradation began, as well as the temperature at which occurs 5, 25 and 50 % weight loss. The studies have shown that the oxygen index of the obtained PUR-PIR foams insignificantly decreases with increasing wood fibers content.