Minor chain reptation

How does the minor chain reptation model work with reference to the ripple experiment (Please limit description to 100 words and a drawing.)... 

Fig. 1. The Minor-Chain Reptation model for diffusion at a polymer-polymer interface is shown in terms of (a) the evolution of the minor chain ends by reptation, (b) the behavior of the minor chains at the interface and (c) the minor chain most probable spherical envelopes. One side of the interface is shown for...

Experiments involving relaxation of centrally deuterated polystyrene chains in a higher molecular weight matrix recently provided support for the minor chain reptation model.Using infrared dichroism studies of step-strained PS films, the protonated chain-ends were found to relax faster than the centrally deuterated fraction. This is consistent with the MC model shown in Fig. 1(a) where the chain-ends first lose memory of their initial orientation. 

We present here a simple experiment, conceived to test both the reptation model and the minor chain model, by Welp et al. [50] and Agrawal et al. [51-53]. Consider the HDH/DHD interface formed with two layers of polystyrene with chain architectures shown in Fig. 5. In one of the layers, the central 50% of the chain is deuterated. This constitutes a triblock copolymer of labeled and normal polystyrene, which is, denoted HDH. In the second layer, the labeling has been reversed so that the two end fractions of the chain are deuterated, denoted by DHD. At temperatures above the glass transition temperature of the polystyrene ( 100°C), the polymer chains begin to interdiffuse across the... 

In the reptation dynamics model, proposed by de Gennes and Edwards, " individual polymer chains are conjectured to move like Brownian snakes in a field (tube) of topological constraints imposed by entanglements from neighbouring chains, (Fig. 1) at f = 0. At time h, some end portions of the chain (these are called the minor chains ) have already escaped from the initial tube by reptation. 

The minor chain (MC) model of reptating chains as shown in Figure 1 was proposed by Kim and Wool to analyze interdiffusion in polymer melts. Only those parts of the chains which have escaped by reptation from their initial tubes (the minor chains) at the time of contact can contribute to interdiffusion. Using this model, the average molecular properties of the interface were derived and are summarized in Table 1. The molecular properties have a common scaling law which relates the dynamic properties, H t)y to the static equilibrium properties, //, via the reduced time, t/T, by t ... 

For the global dynamics governing the rubbery/terminal relaxation, the thermorheological complexity of the components is one of the most prominent features. In PI/PVE blends associated with just a moderate dynamic asymmetry of the components, respective components exhibit very minor complexity and behave similarly to the components in chemically uniform blends such as PI/PI blends, as revealed from rheo-optical and dielectric studies. (PI chains have the type-A dipole so that their global motion is dielectrically detected.) The entanglement relaxation in the PI/PVE blends appears to occur through the mechanisms known for the chemically uniform blends, for example, through the reptation and constraint release (CR)/ dynamic tube dilation (DTD) mechanisms. 

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