Comparative Study on the Properties of Smoke Sheet Rubber Produced by Different Solidification Methods

To investigate the effects of coagulation methods on the structure and properties of sheet rubber, this study prepared natural rubber using different coagulation systems, including acetic acid, formic acid, biological coagulants, and pineapple juice, and systematically analyzed their non-rubber components, gel content, molecular weight distribution, rheological behavior, and mechanical properties of the vulcanized rubber. The results indicate that the type of coagulant significantly affects the protein, phospholipid, and gel content. Among these, the pineapple juice gel exhibited the lowest residual protein content, suggesting that the proteases, organic acids, and active components it contains promote the degradation and removal of non-rubber components. GPC and rheological results show that pineapple juice gel and bio-gel samples possess a broad molecular weight distribution and exhibit a more pronounced viscoelastic response at high temperatures. After uniform vulcanization, the differences in hardness, tensile strength, and tear resistance among the various samples were minimal, indicating that the vulcanized network determines the final mechanical properties, while the coagulation method primarily regulates microstructure and processing behavior. This study provides a theoretical basis for the application of bio-coagulants in the processing of green shikigai gum.