Foaming of trans‐polyisoprene using N2 as the blowing agent

• Published in: Polymers for advanced technologies 2018-02, Vol.29 (2), p.716-725
• Main Authors: Wang, Dan, Prakashan, K., Xia, Lin, Xin, Zhenxiang, Zhang, Zhenxiu
• Format: Article
• Language: English
• Subjects: biomimetic property; Blowing agents; Crosslinking; Curing agents; Density; Foaming; Foams; Physical properties; plastics; Pressure effects; Quenching (cooling); Rubber; Saturation; silica; Silicon dioxide; Temperature; Tensile properties
• ISSN: 1042-7147; 1099-1581
• DOI: 10.1002/pat.4177

Foaming of trans‐1,4‐polyisoprene (TPI) polymer was carried out through a batch process using nitrogen (N2) as the blowing agent. TPI vulcanizates having varying crosslink densities were prepared by varying crosslinking agent content and curing time. The vulcanizates were then saturated with N2 inside a pressure vessel at a pressure of 14 MPa and varying temperatures for 5 hours before effecting the foaming by rapidly quenching the pressure. The effects of varying the crosslinking agent content, silica filler content, and precuring time of the vulcanizates and the effects of varying the gas saturation temperature of foaming on the cell characteristics and physical properties of the foam prepared were investigated. The cells of the TPI foams had a spherical, closed structure. The density, expansion ratio, cell size, cell density, and tensile properties of the foams varied with varying crosslink density of the TPI vulcanizates as well as the saturation temperature of foaming. The important effects of crosslink density and saturation temperature on the N2 solubility in the TPI matrix and thus on the foam expansion were discussed. The silica filler was found to be acting as a cell nucleating agent and reinforcing filler for the TPI foams.