ISSN:
1022-1352
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
New director reorientation experiments with a series of different elastomers are presented. Elastomers with a permanent monodomain structure are stretched perpendicular to their initial director alignment. After a threshold strain is exceeded, stripe-domains are formed parallel to the external stress with alternating sense of rotation in each domain. With increasing network density the average spacing of the stripes decreases. The anisotropy of the polymer chains is varied both by changing the reduced temperature and by introducing smectic clusters via copolymerisation with a mesogen forming a smectic-A phase. The anisotropy of the network is analyzed by the isobaric expansion of the sample parallel to the director as a function of temperature. Reorientation experiments at different reduced temperatures show that the interval of strains, where the director rotates, depends on this anisotropy. The experiments on cybotactic-nematic elastomers reveal that smectic fluctuations give a significant contribution to the threshold. The results are compared to the theory of Warner and Terentjev, yielding a good qualitative agreement.
Additional Material:
12 Ill.
Type of Medium:
Electronic Resource
