Glass point determination
Introduction and Application
Polyethylene terephthalat is a thermoplastic polymer resin of the polyester family and is used in synthetic fibers, beverage, food and other liquid containers, thermoforming applications, and engineering resins often in combination with glass fiber. PET max exist both as an amorphous (transparent) and as a semi-crystalline material.
Analysis using DSC
PET shows at about 77°C a very significant endothermal glass point, when looking at partial crystalline thermo plastic materials. The relation between the exothermal cold crystallization (131°C) and the endothermal melting peak is a method for the degree of crystallization of the material. In the case of PET the crystalline part is very small, giving the material a very good transparency. This is why drinking bottles (cocacola) are very often produced from PET.