October 17, 2024 – In the chemical industry, Polyethylene Terephthalate (PET) and Polyethylene (PE) emerge as two prominent plastic materials, each boasting unique physical attributes and tailored applications.
PET, typically manifesting as a colorless, transparent (amorphous) or milky white (crystalline) substance, exhibits distinctive combustion characteristics. While it is not easily ignited, once ignited, it burns persistently with a yellow flame, blue edges, small droplets falling, and emits black smoke and a pungent odor. However, the pure form of PET does not excel in terms of impact strength and heat resistance. Notably, the integration of glass fiber reinforcement significantly enhances PET’s overall performance.
On the other hand, Polyethylene (PE) presents itself as a milky white, non-toxic, and odorless crystalline plastic with a density ranging from 0.91 to 0.96 g/cm3. According to insights from the Color Masterbatch Industry Network, despite its relatively lower mechanical strength, PE showcases exceptional insulation properties. It remains insoluble in any known solvent at room temperature and demonstrates resistance to diluted sulfuric acid, diluted nitric acid, as well as various concentrations of acid, alkali, and salt solutions. Furthermore, PE possesses a high degree of water resistance, maintaining its performance even after prolonged exposure to water. Although PE exhibits poor water vapor permeability, it excels in permeating oxygen, carbon dioxide, and the vapors of numerous organic substances. Regarding service temperature, PE showcases good weather resistance, with high-pressure PE enduring temperatures around 80°C and low-pressure PE reaching approximately 100°C. Additionally, PE boasts excellent cold resistance, retaining good mechanical properties at -60°C and maintaining a degree of flexibility even at -70°C.
In summary, PET and PE exhibit significant differences in their physical properties and application scenarios. Understanding these distinctions facilitates a more informed selection and utilization of these two materials.