Transcrystalline growth

Fig. 7. Different types of interphases. (a) Contact interphases, as produced for example by transcrystalline growth or enhanced adlayer crosslinking in the adhesive phase, (b) Diffusion interphases, as produced by interdigitation or interdiffusion of chains from either or both phases.

The introduction of fillers to PEEK creates a higher nucleation rate. The surface of carbon fibers and nuclei within the PEEK matrix compete for crystallization growth. Epitaxial transcrystalline growth was frequently observed on the fiber surface in carbon fiber reinforced PEEK composites. 

Figure 5. Transcrystalline growth in polyethylene. From Reference 20.

Natural fibers also act as nucleating agents and enhance the crystallization rate of polymer as reported for PP. The fiber surface roughness of the fiber and thermal stresses were found to facilitate the growth of transcrystallinity on cotton fibers, whereas bamboo fibers induced significant amount of beta form crystals and transcrystalline growth of maleated PP. 

Groeninckx [43] has investigated the isothermal crystallization of polyethyleneterephthalate in the presence of Ti02, kaolin, and Si02. It was observed that the addition of these materials resulted in enhanced heterogeneous nucleation and transcrystalline growth in PET. 

Structure. In polyacetals this has been termed transcrystallinity [159,146]. Transcrystalline growth is controlled by the heat flow to the mold wall and is initiated by the cold mold wall. The melt at the wall cools rapidly, and dense spheru-lite nucleation takes place adjacent to the wall. Spherulites nucleated close to the wall, in the thermal gradient, have parabolic interfaces... 

Cho K W, Kim D W and Yoon S (2003) Effect of substrate surface energy on transcrystalline growth and its effect on interfacial adhesion of semicrystalline polymers. Macromolecules 36 7652-7660. 

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