Mechanical properties of
pure PDMS and the combination between the textile fabric with PDMS
The COVID-19 pandemic created an emergency state that changed daily habits all around the word, imposing restrictive measures as face masks used to curb the virus spread. However, usually masks hide the users face and can affect human interaction and expressions. Moreover, there is an increasing necessity for more comfortable and breathable alternatives. Therefore, PDMS, a transparent elastomer widely used for biomedical applications, is a promising material to achieve these requirements. Also, textile fabrics are already commonly used to cloth masks manufacture because of their availability and cost.
To study how the temperature affects the PDMS properties, tensile tests were conducted according to ASTM D412 standards, using materials cured at 25, 100, 120 and 140ºC. The results showed an increasing on the Young’s Modulus in a range of 0,927-2,196MPa as the temperature increases. Besides that, samples with PDMS and textile fabric were subjected to tensile stress to evaluate how superposition width can affect adhesion in a future mask. These specimens had 3 regions: one with pure PDMS, one only made of woven pressed between two metallic parts and a third one with a combination of both materials. Due to the longer curing time, samples made at 25ºC absorbed more elastomer at the combination region, compromising air permeability and breathability. All specimens broke at PDMS region, showing that textile fabric can be used to enhance the masks tensile resistance. Finally, the highest values of maximum stress were achieved for smaller overlaps, varying approximately 12% when the superposition width reduces from 10 to 5mm. As for curing temperatures, greater resistance was obtained at 120ºC; with values 61% higher than those showed for curing at 25ºC.