Optimizing the lignin based synthesis of flexible polyurethane foams employing reactive liquefying agents

Abstract

The present work is focused on the optimization of a green process based on the employment of by-products obtained from wood treatments as raw materials for producing flexible polyurethane foams. More specifically, lignin was employed in flexible polyurethane foams in order to partially replace the usual fossil polyols; therefore glycerol (GLY) and glycerin polyglycidyl ether (EJ 300) were used as the polyol fraction for lignin liquefaction. Polypropylene glycol triol was used as a chain extender in different ratios with liquefaction solvents, and polymeric diphenylmethane diisocyanate as an isocyanate fraction. Liquefaction of lignin was performed by microwave irradiation, thus reducing the processing time and energy required compared to present industrial production processes. All the foams were produced in controlled expansion through the adoption of a 'one-shot' approach, using water as a blowing agent and with an isocyanate index (NCO/OH) of less than 100 to improve the flexibility of the foam. This approach allowed for the substitution of up to 12% of common petro derived polyol with commercial soda lignin. Finally, the foams were characterized, presenting properties that could be modulated as a function of lignin content, GLY/EJ 300 ratio and isocyanate index. The qualities of the foams were compatible with existing materials used for furniture and for the interiors of car seats and couches.

Exploitation of Arundo donax L. Hydrolysis Residue for the Green Synthesis of Flexible Polyurethane Foams

“…In a previous work, A. donax hydrolysis residue was characterized and compared with ProtoBind 1000, a technical soda lignin used for the synthesis of polyurethane foams (Bernardini et al 2015a, b). It was found that A. donax hydrolysis residue had a brown coal lignite-like elemental composition (C: 63.6%, H: 4.3%, N: 0.7%, O: 31.4%).…”

“…PEG 400 was replaced with the EJ 300, a mixture of glycerol polyglycidyl ethers. The amount of EJ 300 was altered and tested, creating two mixtures named ARF and ARJ using the reported procedure (Bernardini et al 2015a). By lowering the isocyanate index, the lignin content in the final foam was maximized, and foams with stable structures were obtained.…”

“…The compression force deflection test was performed using an Instron 1185 device (Massachusetts, USA), as previously described (Bernardini et al 2015a). The sample size was 30 mm x 30 mm x 30 mm, and a minimum of three replicates for each sample were tested.…”

“…The obtained liquefied mixture was deposited into an 85 x 85 x 55 mm mould, which was closed in order to get a controlled expansion. The foams were kept at room temperature for 3 days and then characterized (Cinelli et al 2013;Bernardini et al 2015a).…”

Characterization of Thermal and Mechanical Properties of Lignosulfonate- and Hydrolyzed Lignosulfonate-based Polyurethane Foams

“…Lignin and its derivatives were employed as renewable resources for flexible (Cinelli et al 2013;Bernardini et al 2015) and rigid (Xue et al 2015) PUR foams. An extensive up-to-date discussion of the pathways for lignin conversion into polyols can be found in the review papers by Matsushita (2015) and Mahmood et al (2016).…”