Diffusion reptation

A comparison of different theories is given under Theories of adhesion. Further considerations of interdiffusion are discussed under Solvent welding, Polymer diffusion reptation and interdigitation and Polymer-poiymer adhesion weid strength. 

In the article on Polymer diffusion reptation and interdigitation, the mechanisms of interdiffusion that may occur when two polymers are brought into good contact were considered. Here, we consider how those mechanisms, and the structure they produce, may be related to the adhesion between the polymers and the strength of the interface formed. 

The self-adhesion (autohesion) of polymers is of considerable practical importance as many moulding operations involve the need for streams of merging polymer melt to self-adhere to form a strong bond necessary to the integrity of the moulded article. Mechanisms of polymer diffusion are discussed in Polymer diffusion reptation and interdigitation and theories that relate interfacial structure to strength in Polymer-polymer adhesion models. In the latter article, the vector percolation (VP) model was described, which is here applied to welding, and the practical consequences of its predictions are drawn out. - ... 

Some rubber-based adhesives need vulcanization to produce adequate ultimate strength, and the adhesion is mainly due to chemical interactions at the interface. Other rubber-based adhesives (see Contact adhesives) do not necessarily need vulcanization but need adequate compounding to produce the adhesive joints, mainly with porous substrates. In this case, the mechanism of diffusion dominates their adhesion properties. See Diffusion theory of adhesion and Polymer diffusion reptation and interdigitation. 

When a polymeric and rubbery substrate is put on contact with silicones, interdiffusion of polymer chains may occur (see Polymer diffusion reptation and interdigitation and Compatibility). The original interface becomes an interphase composed of mixtures of the two polymeric materials. Such a macromolecular interdiffusion process is limited... 

Polymer diffusion reptation and interdigitation R P WOOL Mechanisms for polymer chain diffusion... 

Medium-to-high conversion - immediately after the onset of the gel effect. The diffusion mechanism is complex. Large chains become effectively immobile (on the timescale of the lifetime of a propagating radical) even though the chain ends may move by segmental diffusion, reptation, or reaction diffusion. Monomeric spedes and short chains may still diffuse rapidly. Short-long termination dominates. Initiator efficiencies may reduce with conversion. 

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