Characterization and radiometric studies on poly(methyl methacrylate) doped with some amine derivatives

✍ Scribed by S. M. Sayyah; I. A. Sabbah; F. I. Said

• Publisher: John Wiley and Sons
• Year: 1989
• Tongue: English
• Weight: 461 KB
• Volume: 40
• Category: Article
• ISSN: 0323-7648
• DOI: 10.1002/actp.1989.010400807

✦ Synopsis

Characterization and radiometric studies on poly(methy1 methacrylate) chain a n d t h e adjacent molecules of either solvent or polymer (in a melt). In such a case, t h e above formulation would apply with t h e variation of pressure replacing ST in eqs. (13) a n d (14) a n d t h e variation of volume replacing SU. T h e complex bulk modulus of t h e same form as in eq. (15) will result, but in this case it will have a n isothermal contribution, possibly exceeding t h e thermal one. T h e latter can be verified experimentally, since it is t h e isothermal longitudinal modulus that governs t h e fluctuations observed b y correlation spectroscopy methods in t h e light scattering experiments. Furthermore n o correlation with C&, values is t o be expected for t h e structural mechanism, if t h e volume changes are more important than those of t h e enthalpy. This picture which involves structural rearrangements does n o t conform t o t h e model of a chain interacting with its surroundings as a macroscopic object does with a viscous medium.

It is quite possible t h a t t h e latter model, in spite of its great success in explaining t h e general features of viscoelastic behaviour, will have t o be exchanged for t h e more detailed molecular picture when more subtle properties are considered. T h e above considerations seem t o show t h a t this can b e done without losing t h e benefits of t h e continuous-medium approach, while at t h e same time leaving room for t h e concepts underlying t h e theories of transition t o t h e glass-like behaviour. The desirability of such incorporation has already been mentioned [I, 11, 161.