yongprapat, kamonchai, Nida Chaimoon, and Maneerat Ongwandee. 2021. “Utilization of PU Foam Insulation Waste to Air Purifier Filter”. Naresuan University Engineering Journal 16 (1). Phitsanulok, Thailand:64-72. https://doi.org/10.14456/nuej.2021.7.