ISSN:
0887-624X
Keywords:
PAmXD,6
;
Brabender plastograph
;
hydrolysis
;
condensation
;
equilibrium constant
;
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
PAmXD,6 [poly(m-xylylene adipamide)] was processed using a Brabender plastograph at 30 rpm and at 265 ± 5°C. The evolution of the Mn versus mixing time determined from solution viscosity and chain end concentrations measurements shows that PAmXD,6 undergoes hydrolysis or condensation reactions depending on its initial molecular mass. Lower masses undergo condensation while higher masses undergo hydrolysis. The determination of water concentration in the melt during mixing time confirmed that this behavior is related to an equilibrium constant which was estimated at 500 ± 100. For a mixing period shorter than 20 min, a good correspondence was observed between Mn values determined either by chain end concentrations or by solution viscosity. However, for a mixing period longer than 20 min, discrepancy between Mn values using both methods witnesses the probable appearance of oxidative degradation of PAmXD,6. Mechanisms adapted from the established oxidation reactions of PA6 and PA6,6 are proposed to justify the PAmXD,6 behavior. Those reactions could explain the slight yellowing of PAmXD,6 during its processing. It was also shown that the PAmXD,6 Brabender plastograph mixing torque (30 rpm, 265 ± 5°C) is linearly related to Mn in a log/log diagram. © 1996 John Wiley & Sons, Inc.
Additional Material:
17 Ill.
Type of Medium:
Electronic Resource
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