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Polyurethane foams obtained with low global warming potential and low ozone depletion potential blowing agent.

Cryogenics is the science and technology of very low temperatures, typically below 120 K. The most common applications are liquified natural gas carriers, ground-based tanks, and propellant tanks for space launchers. A crucial aspect of cryogenic technology is effective insulation to minimise boil-off from storage tanks and prevent frost build-up. Rigid closed-cell foams are prominent in various applications, including cryogenic insulation, due to their balance between thermal and mechanical properties. Polyurethane (PU) foam is widely used for internal insulation in cryogenic tanks, providing durability under thermal shocks and operational loads. External insulation, used in liquified natural gas carriers and ground-based tanks, generally demands less compressive strength and can utilise lower-density foams. The evolution of cryogenic insulation materials has seen the incorporation of environmentally friendly blowing agents and bio-based polyols to enhance sustainability. Fourth-generation physical blowing agents, such as HFO-1233zd(E) and HFO-1336mzz(Z), offer low global warming potential and improved thermal conductivity. Additionally, bio-based polyols from renewable resources like different natural oils and recycled polyethylene terephthalate (PET) are being integrated into rigid PU foams, showing promising properties for cryogenic applications. Research continues to optimise these materials for better mechanical performance and environmental impact. [ABSTRACT FROM AUTHOR]

Summary: The effect of intumescent flame retardants on the properties of polyurethane (PU) coatings based on 2 kinds of phosphate ester polyol was studied. Synthesizing polyols, phosphorylation of epoxidized linseed oil with phosphoric acid was performed in the presence of isopropyl alcohol (IPA polyol) or diethylene glycol butyl ether (DGBE polyol). The obtained polyols were characterized by Fourier transform infrared (FTIR) and 31P nuclear magnetic resonance (NMR) spectroscopy. The properties of neat PU coatings based on 2 polyols and those filled with different content (up to 25 wt%) of melamine (Mel), ammonium polyphosphate (APP), and expandable graphite (EG) were studied using thermal gravimetric analysis (TGA), and tensile and cone calorimeter tests. It was found that IPA polyol contained not only phosphate monoesters and diesters, as DGBE polyol, but also phosphate triester and pyrophosphate monoester. Due to this difference, IPA neat and filled coatings had higher tensile characteristics and char residue in a TGA test. Also, the flame retardancy of IPA coatings, compared with that of DGBE coatings, was higher. In a cone calorimeter test, coatings filled with Mel showed a small increase of flame retardancy, but the total smoke release (TSR) of wood samples with coatings decreased noticeably. The effect of APP on the flame retardancy of coatings was higher, but in contrast, the TSR of samples increased with increasing APP content. Even greater decrease of flammability parameters and a simultaneous significant decrease of TSR were shown by the samples with IPA coatings filled with EG. [ABSTRACT FROM AUTHOR]

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