Fire retardancy, thermal, and physico-mechanical properties of semi-rigid water-blown polyurethane foam from palm oil-based polyol

This paper presents the experimental work undertaken to assess rigid palm oil-based polyurethane (PU) foam. The bio-composite foam was characterized to determine its foaming kinetics and morphology, as well as fire retardancy, thermal, and mechanical responses, which was later compared with its petrochemical-based counterpart. The palm oil-based foam displayed poor fire-retardancy performance based on Limiting Oxygen Index (LOI) and UL-94 Vertical Combustion Test. Although less char residue was produced, the palm oil-based PU foam exhibited higher onset degradation temperatures, indicating improved thermal stability. The Scanning Electron Microscopy (SEM) revealed finer cell sizes for the bio-based foam and a higher fraction of open cell structures, which affected its density and compressive properties. As a conclusion, the palm oil-based PU foam is a viable alternative to be utilized in low load-bearing and thermal environment applications.

The effects of the inclusion of 1,2,4-triazole derivatives into the main chains of the polyurethane urea exposed to UV radiation

Linear polyurethane urea containing 1,2,4-triazole segments was obtained by polyaddition of the 3,5-diamino-1,2,4-triazole (DATA) to urethane prepolymer. Also, three crosslinked polymers with different crosslinkers (2,4,6-triaminopyrimidine (TAP), glycerin (Gly), castor oil (CO)) were synthesized. Thermogravimetric analysis, of the obtained polymers, indicated good thermal stability up to 310°C. The polyurethane urea chemical structure was confirmed by FTIR analysis. The glass transition temperatures (Tg) of these polymers, measured by differential scanning calorimetry (DSC), were found in the range of −52°C to −56°C. These values were not significantly influenced by the structure of the hard domain and the intermolecular interactions. The tensile testing showed that the inclusion of 1,2,4-triazole in polyurethane structure substantially improves the tensile strength up to 58 MPa. The obtained polyurethane urea presents surface slight hydrophobic and low interfacial tension. The positive effect of the 1,2,4-triazole segment from the polymer main chain in the UV aging process of these polymer materials has been studied. After exposure to UV radiation, few changes were observed in the molecular structure, in the surface morphology and the mechanical properties.

Synthesis and properties of polyurethane urea with pyridine-2,6-dicarboxamide moieties in their structure

The inclusion of 2,6-pyridinedicarboxamide into polyurethanes structure strongly influenced their morphology, surface and thermo-mechanical properties. The 2,6-pyridinedicarboxamide units adopt syn-syn conformations into polyurethane matrix.

Effect of the hard segment structure on properties of resorcinol derivatives-based polyurethane elastomers

Two series of polyurethane elastomers were obtained from poly(1,4-butylene adipate) diol and 1,6-diisocyanatohexane, which were then chain extended with resorcinol derivatives such as benzene-1,3-diol, 2,4-dihydroxybenzaldehyde, or 1-(2,4-dihydroxyphenyl) hexan-1-one. This article investigates the effects induced in polyurethane elastomer properties by varying the hard segment composition through changing the amount of aliphatic diisocyanate and through the influence of the chemical structure of the resorcinol derivatives’ chain extenders. The different chemical composition and the presence of different dangling chains on the chain extender structure influenced hard segment cohesion, resulting in important effects on the polyurethane elastomer properties. The incorporation of aliphatic diisocyanate alongside the aromatic chain extender leads to changes in the physical and mechanical properties of the polyurethane elastomers compared with aromatic rigid diisocyanates. These polyurethane elastomers were characterized using Fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, and mechanical measurements. We synthesized resorcinol-based polyurethane elastomers with aliphatic–aromatic hard segment structures, with the resorcinol addition making it unnecessary to transform phenolic OH groups into aliphatic OH groups.