Structural, Mechanical, and Thermal Properties

In stretched PPV films, a preferential distribution of crystallites respective to the film surface has been observed. It has been found that two sets of planes, 200 and 110, are preferentially oriented parallel to the film surface. A convolution of a distribution of crystallites with the planes [110] ( 25%), [200] ( 50%), and [iTO] ( 25%) parallel to the film surface resulted in calculated peak profiles similar to the experimental data [130]. 

The crystallite size values for PPV depend on the drawn ratio, and different results were obtained for the lateral crystallite dimensions [75,102,131]. 

In PPV films deposited onto silver substrate, parallel chainlike features were reported, with larger separation (typically 1.8 nm) than expected from the interchain unit cell [132]. This was observed independently of polymer film thickness and material used as substrate and was tentative attributed to some surface reconstruction, possibly due to adsorption of oxygen. Polarization-dependent photoabsorption measurements made in PPV mono-layers prepared by the Langmuir-Blodgett precursor technique onto Mo 2 substrate showed that the phenylene and vinylene moieties are nearly parallel to the surface [125]. 

Side groups also play an important role on structure and ordering. Investigations performed with poly(2,5-dimethoxy-p-phenylene vinylene) demonstrated that the introduction of meth-oxy substituents onto the phenylene rings results in a saw-tooth molecular unit that allows adjacent chains to interlock and pack 

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STRUCTURAL, MECHANICAL AND THERMAL PROPERTIES OF GROUP III NITRIDES... 

In the absence of good quality single crystal samples, the physical properties of indium nitride have been measured on non-ideal thin films, typically ordered polycrystalline material with crystallites in the 50 nm to 500 nm range. Structural, mechanical and thermal properties have only been reported for epitaxial films on non-lattice-matched substrates. 

Volume 6. Solid State Physics—Part A Preparation, Structure, Mechanical and Thermal Properties Part B Electrical, Magnetic and Optical Properties... 

A. Crystal Structure, Mechanical and Thermal Properties Tables 4.1-94 -4.1-99. 

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