Glass transition temperatureversus conversion relationship in the polycyclotrimerization of aromatic dicyanates

✍ Scribed by Lin, Rong-Hsien; Su, An-Chung; Hong, Jinn-Lung

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 232 KB
• Volume: 49
• Category: Article
• ISSN: 0959-8103
• DOI: 10.1002/(sici)1097-0126(200004)49:4<345::aid-pi374>3.0.co;2-d

✦ Synopsis

Comparisons of the effectiveness of different theoretical equations to ®t various sets of experimental T g versus conversion data are made. Among all the theoretical expressions for the T g versus conversion relationship, one-parameter equations give excellent ®tting to the experimental data. The values of parameters obtained thereby can be merely considered as ®tting parameters without realistic physical meanings. Mean-®eld crosslink density and elastically effective crosslink density are derived and applied to the corresponding theoretical equations for comparison in our aromatic dicyanate systems. The Hale±Macosko±Bair (HMB) equation and the so called original DiBenedetto equation combining the mean-®eld crosslink density, rather than elastically effective crosslink density, are applied with success to ®t experimental data; hence the parameter values obtained by this method are more consistent with the original designated physical meanings within the corresponding theoretical frameworks. This is attributed to the fact that the inelastic intramolecular loops may still contribute to the increase in T g , although they make no contribution to the gelation. An expression relating the effect of inelastic intramolecular loops on the gel fraction is also derived. Relationships between the parameters in different theories are discussed.