Low‐temperature oxidation of unstabilized low‐density polyethylene

Abstract

Unstabilized low‐density polyethylene undergoes oxidative destruction in air in the temperature range of 60 to 130°C. As a result gaseous products, mainly lower alkenes, and to the lesser extent lower alkanes are formed, oxygen is absorbed and the samples lose weight. The content of double bonds, OH and groups as well as the value of the surface free energy increases. The mechanical strength of the samples decreases.

Effects of various cleaning agents on polypropylene and copolyester thermoplastic orthodontic retainer materials

“…Glycerol, benzoic acid, and citric acid, which are present in CH, AL, and RB mouthwashes, respectively, may contribute to increasing the stiffness of copolyester by degrading or damaging the material. 22 However, most polymers, including copolyester, are altered dramatically over time by oxidation and degradation after exposure to oxygen, heat, light, and the production process, thus leading to increased stiffness, as described by Piiroja and Lippmaa, 23 Kholodovych, 24 Sepe, 25 and the Polymer Properties Database. 26 In contrast, low hydrolytic stability, wherein water hydrolysis produces physiochemical changes, results in swelling and irreversible degradation, as described by Modjarrad and Ebnesajjad.…”

Untersuchungen zur Bildung transkristalliner Strukturen an Polyethylengrenzflächen. Teil II. Molmassenbestimmung, gravimetrische, DSC‐ und Röntgenkleinwinkelmessungen

“…Aus der Literatur ist bekannt, daB der thermooxidative Abbau von P E sowohl rnit Masseverlust [2] Die heterogene Keimbildung geht im letzteren Fall a n der PE-HD-Oberflache vor sich, und die transkristallinen Schichten wachsen in das bei niedrigen Temperaturen kristallisierende PE-ND hinein (Thermooxidation spielt bei diesem Vorgang keine Rolle). In beiden Fallen ist das Zusammentreffen zweier PE-Schichten mit unterschiedlichem Schmelzpunkt entscheidend fur die Bildung der transkristallinen Schicht.…”