Abiotic degradation of polymeric personal protective equipment by artificial weathering

Abstract

Personal protective equipment (PPE) like single-use face masks is discarded after a single use and poses a significant danger to the environment, resulting in plastic pollution. Most of the face masks are made from synthetic polymers and are non-biodegradable to the environment; hence, concerns are being raised about polymers’ environmental impact. Most of the previous studies so far focus on polypropylene (PP) disposable masks and limited data related to environmental abiotic degradation behavior. There is a lack of studies aiming to understand the degradation behavior of different masks and the influence of physical-chemical factors. In this paper, we report on the environmental abiotic degradation of cloth, surgical and respirator filter facepiece 1 (FFP1) masks by accelerated artificial weathering. Furthermore, physical-chemical properties of masks were characterized by Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC) and Thermo Gravimetric Analysis (TGA). The cloth and FFP1 masks are made from polyethylene terephthalate (PET) and surgical masks were made from polypropylene (PP). Masks were exposed to an accelerated weathering test, which simulates the effects of natural sunlight and reproduces the damage caused by weathering elements such as sunlight, rain and dew. Masks were exposed to Ultraviolet radiation (UV) for 120, 240 and 360 h followed by condensation at 50 °C for 4 h. The FTIR results show that PET cloth and FFP1 PET masks are not degrading with the 360 h maximum exposure duration, which is equivalent to ±180 days. The FTIR scan of the PP surgical mask after 120 h of exposure time shows that it was degraded and broken down into fragments. For the PET cloth mask, a 58% reduction in crystallinity and heat of enthalpy was observed after 120 h of exposure. UV exposure causes a chain scission reaction, breaking down the ester bond in the case of the PET cloth mask. In the case of the PET FFP1 mask exposed to UV for 120, 240 and 360 h, a drastic reduction in crystallinity was observed as compared to the neat (original) PET FFP1 mask. Neat PET cloth and FFP1 masks have higher onset and maximum degradation temperatures as compared to the 120, 240 and 360 h UV exposed masks. Neat PET cloth and FFP1 masks have better resistance to thermal degradation.