Elongational deformation

Strong elongational deformation and use of matrix polymers whose viscosity is higher than that of TLCP phase are better to ensure uniform and fine fibril formation. But application of compatibilizing techniques to in situ composite preparation can be useful to get the most desirable products. These can reduce the high costs of the liquid crystalline polymers and expensive special engineering plastics used for the in situ composite preparation and reduce the processing cost, whereas they can increase the performance of produced in situ composites, hence, their applications, too. 

Note 3 The Finger strain tensor for a steady uniaxial homogeneous elongation deformation or flow of an incompressible viscoelastic liquid or solid is... 

Khan and Armstrong [52] showed that the critical strain, and therefore the yield stress, was dependent on the initial orientation of the cells, for shearing and elongational deformations indeed, for one particular orientation under exten-sional deformation, a yield stress was not observed. Beyond the yield point,... 

This important result indicates that if an interfacial area element is maintained at all times at 45° to the direction of the shear, stretching becomes exponential with shear. In fact, this situation is identical to pure shear or elongational deformation. 

For uniform uniaxial elongational deformation along axis 1, the tensor of the velocity gradients, taking into account the condition of incompressibility, can be written in the form... 

For a system under elongational deformation along direction 1, for a beam of light propagating in direction 3, according to (10.17) one obtains different refractive indices for different polarisation of the beam, so that, for polarisation in directions 1 and 2, one has a difference of refractive indices... 

Axtell and Haworth (1994) showed that rheology, and in particular elongational deformation plays a key role. Ziabicki (1999, 2000) laid a theoretical basis of the role of enhancing the nucleation of crystallisation. 

In elongational rheology the material is subject to stretching (elongational) deformation and elongational rheological properties are determined, Figure 3.64. 

Applications in which dynamic uniaxial elongational viscosities (DUEVs) have been important to the performance of water-borne formulations are discussed. The achievement of high viscosities at low shear rates with minimum mechanical degradation of the water-soluble polymer and with minimum viscoelastic effects in applications that involved converging flows are discussed. These two factors serve as driving forces for the acceptance of hydrophobically modified water-soluble polymers. Complexities arising from the combined contribution of shear and elongational deformations in applications and in their measurement are discussed in the final section. 

Effects of Uniaxial Elongation LDPE films were first stretched to different elongations (deformation speed 1 inch/ min.), then photooxidized while being kept stretched. The extent of oxidation, at a given UV exposure (10 days at 40°C), as a... 

Because the elongational deformation is symmetric with respect to the 8i direction, A2 = A3. Substituting Eq. (5.19) into Eq. (5.16), we obtain... 

These relations enable one to relate the shear viscoelastic functions to their tensile counterparts. At high compliance levels, rubbers are highly incompressible, and the proportional relation between the tensile and shear moduli and compliances holds. However, at lower compliances approaching Jg, the Poison ratio fi (which in an elongational deformation is -(Mw/dM, where w is the specimen s width and / is its length) is less than Eqs. (28) and (29) are then no longer exact. For a glass ju T. When G(t) = K(t), E t) = 2.25 Gif). 

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