Morphological changes of poly(ethylene terephthalate) on multiple steam sterilization

Area of Science:

• Polymer Science
• Materials Science
• Sterilization Technologies

Background:

• Poly(ethylene terephthalate) (PET) is a widely used polymer.
• Sterilization is crucial for medical and food-grade applications of PET.
• Understanding the effects of sterilization on PET properties is essential for material integrity.

Purpose of the Study:

• To investigate the impact of steam sterilization on the thermal and molecular properties of Poly(ethylene terephthalate) (PET).
• To analyze chemical changes, including chain scission and cyclization, induced by autoclaving.
• To assess the potential migration of byproducts and their effect on long-term PET performance.

Main Methods:

• Steam sterilization of PET samples at varying durations (15, 30, 60 min).
• Differential scanning calorimetry (DSC) to determine thermal properties (T m, delta-H, crystallinity).
• Gel permeation liquid chromatography (GPLC) for molecular weight distribution analysis.
• Infrared spectrophotometry (IR) to monitor changes in crystallinity.

Main Results:

• Autoclaving induced chain scission and cyclization reactions in PET.
• Formation of cyclic oligomers was observed.
• These oligomers were found to migrate to the polymer surface.
• Changes in thermal properties and molecular weight distribution were quantified.

Conclusions:

• Steam sterilization significantly alters the molecular structure of PET.
• The formation and migration of cyclic oligomers pose a potential risk to the long-term performance and safety of PET materials.
• Further research is needed to mitigate these effects for critical applications.