Thermal and Mechanical Properties of Polypropylene Gels and Homo Polypropylenes

摘要

A semicrystalline gel is one of the physical gels that attract many interests since the gels are thermo-reversible and hence eco-friendly. Semicrystalline gels have crystalline structures that act as crosslinks distributed over the materials, presenting a repeatable sol-gel transition and gel-sol transition especially by temperature. Some semi-crystalline polymers are reported to make physical gels with several solvents due to their crystalline structures. These semicrystalline gels can transform into a sol state by heating above the gel-sol transition temperature, while the sol state transforms into a gel state by cooling below the sol-gel transition temperature. Isotactic polypropylene (iPP) and syndiotactic polypropylene (sPP), which are two of the most used polyolefins can also create such semicrystalline gels. iPP has the characteristics of heat durability and chemical resistance, presenting faster crystallization and higher Youngs modulus than sPP, while sPP also has the characteristics of heat durability and chemical resistance with more flexible mechanical properties than iPP. Due to these admirable characteristics of PP, they are widely used in many industrial products.