Abstract
Bio-polyols from epoxidized soybean and linseed oils and caprylic acid or 3-phenyl butyric acid were prepared using an environmentally friendly, solvent-free method evaluating the presence of triethylamine as catalyst. Side reactions, leading to a cross-linking structure with high density, were reduced, introducing the catalyst and properly tuning the reaction conditions. A medium functionality value of around 3 along with a hydroxyl number up to around 90 mg KOH/g, narrow polydispersity index, and relatively low molecular mass up to 2400 g/mol were the experimental targets. From selected bio-polyols and an aliphatic partially bio-based isocyanate, a series of water blown polyurethane (PU) foams was produced, estimating the effect of the chemical nature of substituents in the polyol backbone on the PU properties. The apparent density of the foams was in the range of 79–113 kg/m3, with higher values for foams from the aromatic acid. Flexible polyurethane foams with open cell structure from bio-based polyols were obtained, with higher cavity size and lower pore sizes for foams from caprylic acid. The bio-based flexible PU foams showed comparable Young’s moduli (14–18 kPa) and compression deflection values (4.6–5.5 kPa) and exhibited an almost complete recovery of their initial size.
Highlights
We report the synthesis of an innovative family of flexible bio-based polyurethane foams from bio-polyols and TolonateTM, with good appearance and mechanical properties, estimating the effect of the chemical nature of the substituents in the polyol backbone on the PU properties
Renewable bio-polyols with several functionalization degrees were prepared from two different no-food vegetable epoxidized oils coming from soybean (ESO) and linseed (ELO) oil, with approximately 4.3 and 6.4 epoxy per triglyceride, respectively
Bio-polyols were prepared from soybean and linseed oil using a solvent-free method
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Polyurethanes (PUs) are a major polymer family [1], with a global market estimated at approximately €53 billion (sixth among all polymers). Due to the multiplicity of their structures and versatile properties, PUs can be used in various applications. They are mainly found as foams (rigid or flexible based on closed and open cells, respectively), and as denser materials (elastomers, thermoplastics, or thermosets). PUs can be used as blends with other polymers, as coatings, or as composites with fillers [2,3,4,5,6]
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