Author: Lee-Sullivan, P.

Source: Materials Research Innovations, Volume 10, Number 4, December 2006 , pp. 428-433(6)

Publisher: Maney Publishing

Abstract:

The influence of cooling rate on the stress relaxation response of prestrained polyvinylidene fluoride (PVDF) film cooled from 60°C, which is the upper service temperature limit, has been investigated. The film was heated to 60°C, strained at 0·5% and then cooled to ambient between 1 and 5°C min^?1. Subsequently, the heat treated films were subjected to stress relaxation tests at 0·5% strain (50 ?m extension) and the relaxation curves were fitted using the Kohlraush–Williams–Watts (KWW) expression. Modulated differential scanning calorimetry (MDSC) showed that crystallinity changes were only detectable for the highest cooling rate. When the crystallinity level dropped by ?2% for the sample cooled at 5°C min^?1, the relaxation time constant was reduced by nearly two orders of magnitude. The results indicate the film relaxation behavior is highly sensitive to thermomechanical loading near the onset of the ?_c transition. In practical terms, small mechanical straining can dramatically alter PVDF film properties, in terms of material stiffness and viscoelastic response, when operating near the upper service temperature limit.The influence of cooling rate on the stress relaxation response of prestrained polyvinylidene fluoride (PVDF) film cooled from 60°C, which is the upper service temperature limit, has been investigated. The film was heated to 60°C, strained at 0·5% and then cooled to ambient between 1 and 5°C min^?1. Subsequently, the heat treated films were subjected to stress relaxation tests at 0·5% strain (50 ?m extension) and the relaxation curves were fitted using the Kohlraush–Williams–Watts (KWW) expression. Modulated differential scanning calorimetry (MDSC) showed that crystallinity changes were only detectable for the highest cooling rate. When the crystallinity level dropped by ?2% for the sample cooled at 5°C min^?1, the relaxation time constant was reduced by nearly two orders of magnitude. The results indicate the film relaxation behavior is highly sensitive to thermomechanical loading near the onset of the ?_c transition. In practical terms, small mechanical straining can dramatically alter PVDF film properties, in terms of material stiffness and viscoelastic response, when operating near the upper service temperature limit.

References: 12 references open in new window

Articles that cite this article?

Keywords: THERMOMECHANICAL LOADING; DYNAMIC MECHANICAL ANALYSIS; STRESS RELAXATION; MODULATED DIFFERENTIAL SCANNING CALORIMETRY; POLYVINYLIDENE FLUORIDE; DEGREE OF CRYSTALLINITY; COOLING RATE EFFECT

Document Type: Research Article

DOI: http://dx.doi.org/10.1179/143307507X199443

Publication date: 2006-12-01

More about this publication?

• This journal features top 10 articles which are freely available. Please click here and click on the 'Top articles' link in the right-hand menu to view the list and start downloading.
• Editorial Board
• Information for Authors
• Subscribe to this Title
• Terms & Conditions
• Top 10 Articles
• ingentaconnect is not responsible for the content or availability of external websites

Related content

• In this: publication
• By this: publisher
• By this author: Lee-Sullivan, P.

Website © Publishing Technology. Article copyright remains with the publisher, society or author(s) as specified within the article.

• Terms and conditions
• Privacy policy
• Information for advertisers