Preparation, Characterisation, and Application of Bifunctional BaSO₄ Sheets

Barium sulfate (BaSO₄) is a material with high reflectance for preparing bifunctional sheets used in dry reagent chemical tests. In this study, bifunctional BaSO₄ sheets with scattering power and high reflectance were prepared with BaSO₄ microspheres sized 1.3~1.8 μm and cellulose acetate (CA). Factors such as the BaSO₄ morphology, CA dosage, mixing time, surfactant, solid content and wet sheet thickness were investigated. Scanning electron microscopy (SEM), a dynamic contact angle test, light reflection detector and light reflection densitometer were employed to characterize the structure and properties of bifunctional BaSO₄ sheets. The optimal conditions for preparing bifunctional BaSO₄ sheets under natural drying conditions were as follows: mass ratio of CA to BaSO₄ microspheres was 0.03:1; mixing acetone solution was used to form liquid stock puree; 35 μL Tween-80 was used to improve the hydrophilicity of bifunctional sheets; solid content was 54.9%; mixing 2 h then 450 µm thick sheets were cast on a glass plate using a film applicator. The light reflectance value of bifunctional BaSO₄ sheets in the range of 400~800 nm was higher than 97%. Serum diffused in bifunctional BaSO₄ sheets reacted in reagent sheets and formed uniform colorful spots. Considering the repeatability of spot proportion and light reflectance value, the sheet offered a uniform serum scattering power and good repeatability. Therefore, the bifunctional BaSO₄ sheets are regarded as a promising material for dry chemical diagnostic reagents.