The mask sample is from winner medical, and it was bought form drugstore. Winner Medical was founded in 1991, additionally, the company has become the leading manufacturer for disposable wound-care and surgical products in China.[12] Masks are one of the common objects in our daily life. Mask is often used to filter dust, odor and so on. So they are widely used in construction sites or hospitals. People also wear masks to cope with the smog in their daily life. Over the past year or so, masks have become indispensable because of the COVID-19 epidemic. Masks are required for outdoor activities such as work, travel and shopping. And polypropylene happens to be an important raw material for medical masks, which is an important reason why we choose masks as samples.

                                    Figure. Our sample - masks