Thermo‐mechanical property enhancement of rigid polyurethane foam composite using low cost, environment friendly fly ash over silica particles

• Published in: Journal of vinyl & additive technology 2024-01, Vol.30 (1), p.156-171
• Main Authors: Polimera, Srihith, Gali, A., Rahaman, Ariful, Chandan, Mohammed Rehaan, Balakumaran, S. J., Nath, Susanta Kumar
• Format: Article
• Language: English
• Subjects: Additives; Calorific value; Closed loops; Compressive strength; Fly ash; Glass transition temperature; Low cost; Plastic foam; Polyurethane foam; polyurethanes; Silicon dioxide; Supply chains; thermal properties; Thermodynamic properties; Timber construction; Ureas; Water absorption
• ISSN: 1083-5601; 1548-0585
• DOI: 10.1002/vnl.22036

Low cost and environment friendly fly ash particles and silica particles were used as additives in the rigid polyurethane foam composite. The usage of fly ash will decrease the need for its handling and exposure to environment. FTIR spectra show the absence of hydrogen bonded urea which indicates no aggregation of hard urea domains in the soft polyurethane matrix after the addition of silica/fly ash. The composite loaded with 20 weight percentage fly ash had the highest glass transition temperature. At 10 weight percentage of the additive, the gross calorific value in the fly ash loaded composite decreased by 12% when compared with the composite loaded with silica. Introduction of fly ash into the foam composite up to a certain weight percentage (10 wt%) enhanced the compressive strength of the rigid polyurethane foam composite. The percolate particle concentration was at 10 weight percentage of the additive. The addition of fly ash increased the compressive strength up to 21% compared to the foam composite loaded with silica. Addition of fly ash in the foam composite resulted in a decrease of water absorption up to 23% in comparison to the composite loaded with silica. Hence, low cost and environment friendly fly ash is suitable additive which can be loaded into rigid polyurethane foams for superior enhancement in mechanical and thermal properties. Highlights The addition of fly ash to the foam decreased the gross calorific value up to 12% compared to that of the silica loaded foam composite. The composite loaded with fly ash had highest normalized compressive strength and highest glass transition temperature than that of the unloaded foam. This can potentially replace conventional rigid polyurethane foam in timber constructions because of its higher compressive strength. We propose the addition of fly ash as a low cost, environment friendly additive as it improved the various properties of the polyurethane foam composite to a greater extent than silica particles. The greater usage of fly ash will help in the formation of a closed loop supply chain and alleviate the need for disposal of fly ash. Rigid polyurethane foam composites loaded with varying weight percentage (5%, 10%, 15%, and 20%) of silica and low cost, environment friendly Class F fly ash as additive particles were synthesized. FTIR spectroscopy had shown that the hard urea domains were well dispersed in the foam matrix. At 20 weight percentage of the additive, the glass transition temperature