Abstract
A second-generation bio-based feedstock—tall oil fatty acids—was epoxidised via two pathways. Oxirane rings were introduced into the fatty acid carbon backbone using a heterogeneous epoxidation catalyst-ion exchange resin Amberlite IR-120 H or enzyme catalyst Candida antarctica lipase B under the trade name Novozym® 435. High functionality bio-polyols were synthesised from the obtained epoxidated tall oil fatty acids by oxirane ring-opening and subsequent esterification reactions with different polyfunctional alcohols: trimethylolpropane and triethanolamine. The synthesised epoxidised tall oil fatty acids (ETOFA) were studied by proton nuclear magnetic resonance. The chemical structure of obtained polyols was studied by Fourier-transform infrared spectroscopy and size exclusion chromatography. Average molecular weight and polydispersity of polyols were determined from size exclusion chromatography data. The obtained polyols were used to develop rigid polyurethane (PU) foam thermal insulation material with an approximate density of 40 kg/m3. Thermal conductivity, apparent density and compression strength of the rigid PU foams were determined. The rigid PU foams obtained from polyols synthesised using Novozym® 435 catalyst had superior properties in comparison to rigid PU foams obtained from polyols synthesised using Amberlite IR-120 H. The developed rigid PU foams had an excellent thermal conductivity of 21.2–25.9 mW/(m·K).
Highlights
Due to environmental concerns, new regulatory policies and a shift in consumer requirements, renewable resources for polymer materials have been widely studied in the last decade [1]
The synthesised Tall oil fatty acids (TOFA) bio-polyols have high OH values and low acid value, which is typical and necessary for polyols to be used for rigid PU foam production
It is crucial to mention that the TOFA-based rigid PU foams were developed using namely, the isocyanate index, which was 110, whereas the present study describes rigid only bio-based polyols in the formulation
Summary
New regulatory policies and a shift in consumer requirements, renewable resources for polymer materials have been widely studied in the last decade [1]. As well as nowadays, fatty acids present in plants in the form of triglycerides are one of the most appropriate raw products for the manufacturing of bio-based materials [2]. Epoxides are one of the most versatile intermediates to be further used for the synthesis of different compounds and has a wide commercial use because of its high reactivity [8]. Numerous epoxidation methods of different kind of vegetable oils, such as canolarapeseed [9,10], palm [11], cottonseed [12], soybean [13], castor [14], linseed [15], mahua [16]. Non-edible plant oils, such as tall oil [18,19,20] and jatropha [21,22], have been successfully epoxidised previously
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