Hardness gradient regulation of Eucommia ulmoides gum-based shape memory materials and their application in non-invasive ventilation (NIV) masks

Faced with multiple diseases such as chronic obstructive pulmonary disease (COPD), cardiogenic pulmonary edema and obstructive sleep apnea-hypopnea syndrome (OSAHS), there is an urgent need for non-invasive ventilation (NIV) masks. Traditional NIV masks have problems such as air leakage, limited adaptability and secondary contusion for patients. A personalized NIV mask with shape memory characteristics based on Eucommia ulmoides gum (EUG) has been developed in this study. Styrene-ethylene-butene-styrene block copolymer (SEBS) was filled into Eucommia ulmoides gum by physical blending to accelerate its shape fixation rate, and a series of hard EUG-SEBS shape memory materials were prepared. Meanwhile, natural rubber (NR) was added to Eucommia ulmoides gum to prepare a series of soft EUG-NR shape memory materials. Adding NR gradually reduces the hardness gradient of the composite material while ensuring a high shape-fixation rate. The experimental results show that the shape-fixation rate of EUG-5SEBS had the highest value of 95.5%; when the mass ratio of EUG to NR was 80/20, the composite material exhibited the best comprehensive performance, with a shape-fixation rate of 75.78% and a Shore A hardness of 87. Layers of rigid polyurethane, EUG-5SEBS, EUG80-NR20 and NR, were combined to manufacture personalized non-invasive ventilation masks with shape-memory properties to meet the goals of compliance across different face shapes. A comfort survey showed that this mask was more comfortable than conventional airbag masks.