Films semicrystalline

A. Ruseckas, E.B. Namadas, T. Ganguly, M. Theander, M. Svensson, M.R. Andersson, O. Inganas, and V. Sundstrom, Intra- and interchain luminescence in amorphous and semicrystalline films of phenyl-substituted polythiophene, J. Phys. Chem. B, 105 7624-7631, 2001. 

NP(OCH2CF3)2k 242 66 Semicrystalline, film-and fibre-forming material... 

The unique piezoelectric and pyroelectric properties of semicrystalline films of PVDF arise from changes in the polarization imparted to the overall film by the crystalline P-phase. The polar nature of the P-phase is, in turn, a direct result of the parallel alignment of the dipole moment of the repeat units in the unit cell (Figure 11.1). The crystal polarization is defined as the dipole moment density of the crystal ... 

Poly(ethylene terephthalate) (PET), eg. DuPont Teijin Films Melinex polyester film, and poly(ethylene naphthalate) (PEN), eg. DuPont Teijin Films Teonex polyester film, are biaxially oriented semicrystalline films [1], The chemical structures of PET and PEN are shown in Fig. 7.1. 

In 1996, Park and Cima reported cell adhesion differences with respect to two different types of films [11]. The as-received material from which the films were made was the same, but one set of film was processed to have relatively low crystallinity or essentially amorphous qualities, and the other one was processed to semicrystallinity. Hepatocytes that were grown on the semicrystalline films formed spheroids very quickly, whereas the same cells on a... 

Poly(ethylene terephthalate) semicrystalline films have been metallized with Al and Cu by using Knudsen effusion cells. During the metal deposition, the surface was characterized by static SIMS. The secondary ions characteristics of the polymer and the new contributions produced by the metal and metal-polymer fragments were followed as a function of the deposition time. It is observed that the binetlcs is very different for the two metals it is faster for Al as compared to Cu. After an Al deposition... 

Ruseckas, A., et al. 2001. Intra- and interchain luminescence in amorphous and semicrystalline films of phenyl-substituted polythiophene. J Phys Chem B 105 7624. 

Structures in model semicrystalline films may be larger and better defined than in commercial materials because of lower nuclea-tion densities or lower quenching rates. 

Model film studies are more appropriate and easier to relate to commercial films in cases where the orientation is low or primarily uniaxial, as biaxial orientation is difficult to mimic on a small scale. Films with large second phase particles also cannot be studied by this method as the true structure cannot be reproduced in a thin film. Nevertheless, many of the basic concepts used in describing nucrostructure and its development in films, particularly semicrystalline films, have been derived from model film studies. 

Semicrystalline films of very low molecular weight polymer ([ti] 0,12) were obtained when pressed from the melt at 228 C. However, pressed films of higher molecular weight polymers were not crystalline. It was necessary to add small amounts of plasticizer to obtain some crystallinity. This is probably due to the fact that above a certain degree of polymerization, the increasing melt viscosity restricts the mobility of the chains and prevents rapid crystallization. 

---