Laser flash pyrolysis of face mask waste to vinylidene-terminated PP wax and further functionalized as compatibilizer

Hao-Qin Zhang; Lun Chen; Chang-Qian Chen; Fu-Lu Chang; Yi-Xun Tian; Xia Jiang; Wei-Tao Huang; Bin Hu; Xian-Wu Cao; Xiao-Chun Yin; Guang-Jian He

doi:10.1016/j.wasman.2024.11.036

Laser flash pyrolysis of face mask waste to vinylidene-terminated PP wax and further functionalized as compatibilizer

Waste Manag. 2024 Nov 29:192:91-101. doi: 10.1016/j.wasman.2024.11.036. Online ahead of print.

Authors

Affiliations

¹ Key Laboratory of Polymer Processing Engineering Ministry of Education, Guangzhou, China; National Engineering Research Center of Novel Equipment for Polymer Processing, Guangzhou, China; Guangdong Provincial Key Laboratory of Technique and Equipment for Macromolecular Advanced Manufacturing, School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou, China.
² CATARC Automotive Inspection Center (Wuhan) Co., Ltd., Wuhan, China.
³ Key Laboratory of Polymer Processing Engineering Ministry of Education, Guangzhou, China; National Engineering Research Center of Novel Equipment for Polymer Processing, Guangzhou, China; Guangdong Provincial Key Laboratory of Technique and Equipment for Macromolecular Advanced Manufacturing, School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou, China. Electronic address: hegj@scut.edu.cn.

PMID: 39615290
DOI: 10.1016/j.wasman.2024.11.036

Abstract

During the COVID-19 pandemic, face masks, as personal protective equipment (PPE) against the coronavirus (SARS-CoV-2), have been widely used worldwide. How to properly dispose of used PPE has brought a huge challenge to the ecosystem and human health. Here we proposed a laser flash pyrolysis (LFP) strategy to upcycle the used polypropylene(PP) face mask to vinylidene-terminated PP wax (PP-VDT) and further functionalized for compatibilizer application. Carbon black (0.2 wt%) was mixed with masks as a light absorbent to improve photothermal conversion efficiency. An infrared laser was adopted as the thermal source to quickly depolymerize the used PP face mask within just several milliseconds. The pyrolysis fragments quickly vaporized out to form PP-VDT with high selectivity (average terminal vinylidene per molecular chain was up to 1.55). The PP-VDT appeared as white solid particles which were clean and high purity. In addition, PP-VDT as polymer precursors could be further functionalized by thiol-ene chemistry to hydroxyl-terminated PP (PP-OH) and isocyanate-terminated PP (PP-HMDI), which could be used as compatibilizer in PLA/PP blends to decrease the size of the dispersed PP phase and to improve tensile strength. Therefore, this LFP technique was an effective upcycling method for PP face masks to obtain value-added products.

Keywords: Laser flash pyrolysis; Polypropylene; Used face masks; Vinylidene-terminated PP wax.