Mechanical relaxations in heat-aged polycarbonate. Part II: statistical analysis of low-molecular weight data.: An article from: Polymer Engineering and Science
Book Details
Author(s)Donna Dykeman, Pearl Lee-Sullivan
PublisherSociety of Plastics Engineers, Inc.
ISBN / ASINB0008DATY6
ISBN-13978B0008DATY8
MarketplaceFrance 🇫🇷
Description
This digital document is an article from Polymer Engineering and Science, published by Society of Plastics Engineers, Inc. on February 1, 2003. The length of the article is 7937 words. The page length shown above is based on a typical 300-word page. The article is delivered in HTML format and is available in your Amazon.com Digital Locker immediately after purchase. You can view it with any web browser.
From the author: The significance of heat-aging effects on low-molecular-weight polycarbonate has been studied by performing a two-factor Analysis of Variance (ANOVA). Although this work was primarily motivated by the large experimental scatter observed in stress relaxation results for LMW 2608 (Part I), the effect of heat-aging on the characteristics of secondary transitions ([gamma] and [[beta].sub.1]) generated by dynamic testing was also investigated. Both types of tests were performed using a dynamic mechanical analyzer. The statistical analysis verified an earlier suggestion that both the secondary transitions were insensitive to heat-aging. In the quasi-static stress relaxation tests, the curve-fitted KWW parameters ([tau], [E.sub.o], [beta]') were evaluated using ANOVA for increasing heat-aging time and test temperature. Two other statistical techniques were also applied to test repeatability--the power of each aging time/test temperature combination and the number of observations needed to achieve 90% repeatability. In conclusion, both [tau] and [beta]' could describe the self-retarding nature of volume recovery although the repeatability of [beta]' was substantially higher. However, the unrelaxed modulus. [E.sub.o], was found to be an unreliable indicator of whether heat-treatment had caused changes in the intrinsic structure. Overall, the study showed that the repeatability of the stress relaxation test results is generally very poor for the confidence levels tested.
Citation Details
Title: Mechanical relaxations in heat-aged polycarbonate. Part II: statistical analysis of low-molecular weight data.
Author: Donna Dykeman
Publication:Polymer Engineering and Science (Refereed)
Date: February 1, 2003
Publisher: Society of Plastics Engineers, Inc.
Volume: 43 Issue: 2 Page: 383(15)
Distributed by Thomson Gale
From the author: The significance of heat-aging effects on low-molecular-weight polycarbonate has been studied by performing a two-factor Analysis of Variance (ANOVA). Although this work was primarily motivated by the large experimental scatter observed in stress relaxation results for LMW 2608 (Part I), the effect of heat-aging on the characteristics of secondary transitions ([gamma] and [[beta].sub.1]) generated by dynamic testing was also investigated. Both types of tests were performed using a dynamic mechanical analyzer. The statistical analysis verified an earlier suggestion that both the secondary transitions were insensitive to heat-aging. In the quasi-static stress relaxation tests, the curve-fitted KWW parameters ([tau], [E.sub.o], [beta]') were evaluated using ANOVA for increasing heat-aging time and test temperature. Two other statistical techniques were also applied to test repeatability--the power of each aging time/test temperature combination and the number of observations needed to achieve 90% repeatability. In conclusion, both [tau] and [beta]' could describe the self-retarding nature of volume recovery although the repeatability of [beta]' was substantially higher. However, the unrelaxed modulus. [E.sub.o], was found to be an unreliable indicator of whether heat-treatment had caused changes in the intrinsic structure. Overall, the study showed that the repeatability of the stress relaxation test results is generally very poor for the confidence levels tested.
Citation Details
Title: Mechanical relaxations in heat-aged polycarbonate. Part II: statistical analysis of low-molecular weight data.
Author: Donna Dykeman
Publication:Polymer Engineering and Science (Refereed)
Date: February 1, 2003
Publisher: Society of Plastics Engineers, Inc.
Volume: 43 Issue: 2 Page: 383(15)
Distributed by Thomson Gale
