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Title: Optical characterization of phase transitions in pure polymers and blends

To study the optical properties of polymeric samples, an experimental apparatus was designed on purpose and set up. The sample is a thin film enclosed between two glass slides and a PTFE frame, with a very thin thermocouple placed on sample for direct temperature measurement. This sample holder was placed between two aluminum slabs, equipped with a narrow slit for optical measurements and with electrical resistances for temperature control. Sample was enlightened by a laser diode, whereas transmitted light was detected with a photodiode. Measurements were carried out on polyethylene-terephtalate (PET) and two different polyamides, tested as pure polymers and blends. The thermal history imposed to the sample consisted in a rapid heating from ambient temperature to a certain temperature below the melting point, a stabilization period, and then a heating at constant rate. After a second stabilization period, the sample was cooled. The data obtained were compared with DSC measurements performed with the same thermal history. In correspondence with transitions detected via DSC (e.g. melting, crystallization and cold crystallization), the optical signal showed a steep variation. In particular, crystallization resulted in a rapid decrease of transmitted light, whereas melting gave up an increase of light transmitted by the sample.more » Further variations in transmitted light were recorded for blends, after melting: those results may be related to other phase transitions, e.g. liquid-liquid phase separation. All things considered, the apparatus can be used to get reliable data on phase transitions in polymeric systems.« less
Authors:
; ;  [1]
  1. Department of Civil, Environmental, Aerospace and Materials Engineering (DICAM), University of Palermo, Viale delle Scienze, Ed. 8, 90128 Palermo (Italy)
Publication Date:
OSTI Identifier:
22494365
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1695; Journal Issue: 1; Conference: GT70 international conference on polymer processing with resulting morphology and properties: Feet in the present and eyes at the future, Salerno (Italy), 15-17 Oct 2015; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ALUMINIUM; CALORIMETRY; COMPARATIVE EVALUATIONS; CRYSTALLIZATION; ELECTRIC CONDUCTIVITY; GLASS; HEATING; LASERS; LIQUIDS; MELTING; MELTING POINTS; OPTICAL PROPERTIES; POLYAMIDES; SAMPLE HOLDERS; SIGNALS; TEFLON; TEMPERATURE CONTROL; TEMPERATURE MEASUREMENT; THERMOCOUPLES; THIN FILMS