Chemically recycled commercial polyurethane (PUR) foam using 2-hydroxypropyl ricinoleate as a glycolysis reactant for flexibility-enhanced automotive applications

Abstract

The automotive industry uses polyurethane (PUR) foam core in the vehicle headliner composite. The sector demands recycling suggestions to reduce its scrap and decrease the expenses. This work investigated the PUR depolymerization using synthesized 2-hydroxypropyl ricinoleate (2-HPR) from castor oil and incorporated the liquid recyclate (REC) into the original PUR foam. The synthesis of 2-HPR yielded 97.5%, and the following PUR depolymerization (via glycolysis) reached 87.2% yield. The synthesized products were verified by GPC, FTIR, ESI-MS, and ¹H NMR cross-analysis. The laboratory experiments (565 mL) included rheological, structural, and reactivity investigations. Added 30% REC content decreased the apparent viscosity to 109 mPa s from standard 274 mPa s. The reactivity of the 30% REC system increased by 51.2% based on the cream time due to the high REC amine value. The block foam density of systems with 15% REC and above decreased by 14.8%. A system with 20% REC content was the most prospective for up-scale. The industrially significant up-scale (125 L) was performed successfully, and the tensile and flexural test specimens were sampled from the up-scaled foam. The tensile characteristic (tensile strength 107 ± 8 kPa and elongation 9.2 ± 0.7%) and flexural characteristic (flexural strength 156 ± 12 kPa and flexural strain at deformation limit 23.4 ± 0.6%) confirmed that the REC incorporation in the standard PUR foam improves the applicable significant mechanical properties and assures the manufacture improve.