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.

The most common sustainable solution for polyurethane (PU) materials is their production using renewable resources. Polyols derived from biomass and recycled polymers are the most promising way to do that. This study compares five different sustainable polyols as a possible raw material for production of highdensity rigid PU foams for automotive application. The goal of our study was to show that biobased polyols are a suitable replacement for polyols derived from petrochemical products. The influence of the chemical structure of polyols on the PU polymer matrix and foam properties was investigated. Two sources of PU raw material feedstock were studied: the plant biomass and the side stream of poly(ethylene terephthalate) (PET) production. Three different polyols from renewable resources were investigated as well as two aromatic polyester polyols. High-density rigid polyurethane foams were developed from these raw materials. This was done to choose a material, which could be used as the core of structural elements for lightweight vehicles. The focus was put on the sustainability and competitive properties of the developed materials. The obtained results led to the conclusion that recycled PET polyols show a higher mechanical strength. Nevertheless, renewable resources are closely matched.

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.

In this research, polyols from rapeseed oil and recycled poly(ethylene terephthalate) were synthesized by two-step continuous synthesis with a different rapeseed oil and poly(ethylene terephthalate) concentration. All rapeseed oil/poly(ethylene terephthalate) polyols showed complete compatibility with blowing agent Solkane 365/227. The resulting polyols were used to prepare rigid polyurethane foams which were characterized with various techniques for determination of their physical, mechanical and thermal insulation properties. The effect of rapeseed oil and poly(ethylene terephthalate) concentrations in polyols on the characteristics of rigid polyurethane foams was investigated. The results showed that obtained rigid polyurethane foams were suitable for thermal insulation appliance. Also, the potential use of rapeseed oil as raw material combined with poly(ethylene terephthalate) to synthesize polyols with good compatibility with blowing agent was confirmed.