ISSN:
0021-8995
Schlagwort(e):
Chemistry
;
Polymer and Materials Science
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
,
Maschinenbau
,
Physik
Notizen:
The rheology and development of the texture of immiscible polymer blends based on poly(ethylene terephthalate) (PET) and nylon 6,6 at composition ratios of 75/25, 50/50, and 25/75 w/w PET/nylon 6,6 were studied. The blends were prepared by mixing in an extruder and by dry blending and mixing between cone-and-plate fixtures in a nitrogen atmosphere. The rheology of these blends was found to be a function of both polymer degradation and the two-phase morphology. An accelerated degradation rate in air was observed for the 75/25 and 50/50 w/w PET/nylon 6,6 blends relative to the neat polymers while the blend at a weight ratio of 25/75 w/w PET/nylon 6,6 displayed a rate of degradation similar to that of the neat polymers. The values of the steady shear viscosity (η), |η*| storage modulus (G′), and steady-state first normal stress difference (N1) for melt-blended 75/25 and 50/50 w/w PET/nylon 6,6 samples were lower than those of the neat polymers and were determined to be a consequence of the higher rate of degradation of these blends during extrusion relative to that of the neat polymers. The role played by the two-phase nature on the blends was observed for all samples prepared by dry blending and mixing in cone-and-plate fixtures under a nitrogen atmosphere and for the melt-blended 25/75 w/w PET/nylon 6,6 blend. The two-phase nature of the dry-blended samples and the extruded 25/75 w/w PET/nylon 6,6 sample resulted in values of |η*|, η, G′, and N1 which were higher than those of the neat polymers. Transient behavior observed for the blends using stepwise changes of shear rate was found to superimpose when plotted in reduced form, indicating that at rates lower than the longest relaxation time of the neat polymers there was no intrinsic time constant associated with the deformation of the interface in the blends. © 1996 John Wiley & Sons, Inc.
Zusätzliches Material:
18 Ill.
Materialart:
Digitale Medien
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