Bio-Based Rigid Polyurethane Foams Modified with Phosphorus Flame Retardants

Rigid polyurethane foams (RPURF) containing a bio-polyol from rapeseed oil and different phosphorus-based flame retardants were obtained. Triethyl phosphate (TEP), dimethyl propane phosphonate (DMPP) and cyclic phosphonates Addforce CT 901 (20 parts per hundred polyol by weight) were used in the synthesis of RPURF. The influence of used flame retardants on foaming process, cell structure, and physical–mechanical properties as well as flammability of RPURF were examined. The addition of flame retardants influenced the parameters of the cellular structure and decreased compressive strength. All obtained foam materials had a low thermal conductivity coefficient, which allows them to be used as thermal insulation. The research results of bio-based RPURF were compared with foams obtained without bio-polyol. All modified materials had an oxygen index above 21 vol%; therefore, they can be classified as self-extinguishing materials. The analysis of parameters obtained after the cone calorimeter test showed that the modified RPURF have a lower tendency to fire development compared to the reference foams, which was particularly noticeable for the materials with the addition of DMPP.

High performance biobased pour-in-place rigid polyurethane foams from facile prepared castor oil-based polyol: Good compatibility with pentane series blowing agent

In this paper, biobased and environmentally friendly rigid polyurethane foams (RPUF) from high hydroxyl value castor oil-based polyols have been prepared without the addition of petroleum-based polyols in the formulation. The new Biopolyol with high hydroxyl value was designed on the basis of the analysis of functionality, structure and hydroxyl value relation and synthesized directly from castor oil in a facile one-pot three-step system. A series of Biopolyols with hydroxyl values in the range of 550–650 mg KOH/g were obtained through transesterification, epoxidation, and hydrolysis. The Biopolyol chemical structure was characterized using FT-IR,1H NMR spectroscopies. The formulated blend polyol with amine catalysts and cyclopentane as a blowing agent have good cyclopentane solubility and phase separation between cyclopentane and polyol was not observed after 30 days. The foaming characteristics were evaluated and improved results were obtained. The thermal conductivity, thermal stability, compressive strength, morphology, dimensional stability, density, and foam flow of the RPUFs were characterized. The results are compared with RPUF prepared using standard commercial polyether polyols for pour-in-place RPUFs. The prepared biobased RPUFs from Biopolyol was able to reach the required satisfactory properties for the appliance industry.

Natural Oil-Based Rigid Polyurethane Foam Thermal Insulation Applicable at Cryogenic Temperatures

This paper presents research into the preparation of rigid polyurethane foams with bio-polyols from rapeseed and tall oil. Rigid polyurethane foams were designed with a cryogenic insulation application for aerospace in mind. The polyurethane systems containing non-renewable diethylene glycol (DEG) were modified by replacing it with rapeseed oil-based low functional polyol (LF), obtained by a two-step reaction of epoxidation and oxirane ring opening with 1-hexanol. It was observed that as the proportion of the LF polyol in the polyurethane system increased, so too did the apparent density of the foam material. An increase in the value of the thermal conductivity coefficient was associated with an increase in the value of apparent density. Mechanical tests showed that the rigid polyurethane foam had higher compressive strength at cryogenic temperatures compared with the values obtained at room temperature. The adhesion test indicated that the foams subjected to cryo-shock obtained similar values of adhesion strength to the materials that were not subjected to this test. The results obtained were higher than 0.1 MPa, which is a favourable value for foam materials in low-temperature applications.

Fly Ash as an Eco-Friendly Filler for Rigid Polyurethane Foams Modification

There is currently a growing demand for more effective thermal insulation materials with the best performance properties. This research paper presents the investigation results on the influence of two types of filler on the structure and properties of rigid polyurethane foam composites. Fly ash as a product of coal combustion in power plants and microspheres of 5, 10, 15, and 20 wt.%, were used as rigid polyurethane foams modifiers. The results of thermal analysis, mechanical properties testing, and cellular structure investigation performed for polyurethane composites show that the addition of fly ash, up to 10 wt.%, significantly improved the majority of the tested parameters. The use of up to 20 wt.% of microspheres improves the mechanical and thermal properties and thermal stability of rigid polyurethane foams.

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.