Morphological changes of poly(ethylene terephthalate) on multiple steam sterilization.
Poly(ethylene terephthalate) (PET) was steam sterilized by autoclaving for 15, 30 and 60 min.  The thermal properties, T m, delta-H and percent crystallinity were determined using differential scanning calorimetry.  Molecular weight distribution was determined using gel permeation liquid chromatography.  Crystallinity of PET was also monitored by infrared spectrophotometry.  The analyses indicate that that chain scission and cyclization reactions take place in PET, forming cyclic oligomers, that can migrate to the polymer surface and which may affect long term performance of PET.
Division for Technical Evaluation of Biomaterials, Sree Chitra Tirunal Institute for Medical Sciences and Technology, India.
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D002152:Calorimetry, Differential Scanning; D006801:Humans; D008422:Materials Testing; D008970:Molecular Weight; D011093:Polyethylene Terephthalates / Q000737:chemistry*; D013227:Steam; D013242:Sterilization / Q000379:methods