Polymer morphology process

Rotations around torsional barriers induce changes in chain conformation. For conjugated systems like polydiacetylenes, flow-induced changes in chain conformation can have a profound influence on the photon absorption and electronic conductivity properties of the material [73]. Flow-induced changes in molecular conformation form the basis for several technically important processes, the best known examples are the production of oriented fibers by gel spinning [74], the compatibility enhancement [75] and the shear-induced modification of polymer morphology [76]. 

Advanced computational models are also developed to understand the formation of polymer microstructure and polymer morphology. Nonuniform compositional distribution in olefin copolymers can affect the chain solubility of highly crystalline polymers. When such compositional nonuniformity is present, hydrodynamic volume distribution measured by size exclusion chromatography does not match the exact copolymer molecular weight distribution. Therefore, it is necessary to calculate the hydrodynamic volume distribution from a copolymer kinetic model and to relate it to the copolymer molecular weight distribution. The finite molecular weight moment techniques that were developed for free radical homo- and co-polymerization processes can be used for such calculations [1,14,15]. 

The matrix polymer morphology of a collection of LDPE foams manufactured from a high-pressure nitrogen solution process was analysed at different length scales. 

Properties of peroxide cross-linked polyethylene foams manufactured by a nitrogen solution process, were examined for thermal conductivity, cellular structure and matrix polymer morphology. Theoretical models were used to determine the relative contributions of each heat transfer mechanism to the total thermal conductivity. Thermal radiation was found to contribute some 22-34% of the total and this was related to the foam s mean cell structure and the presence of any carbon black filler. There was no clear trend of thermal conductivity with density, but mainly by cell size. 27 refs. 

Provder, T. 2006. Film Formation, Process, and Morphology. Oxford University Press, New York. Rudin, A. 1998. Elements of Polymer Science and Technology, 2nd ed. Academic, Orlando, EL. Shibaev, V. and Lam, L. 1993. Liquid Crystalline and Mesomorphic Polymers. Springer, New York. Sinha, R. 2002. Outlines of Polymer Technology Manufacture of Polymers and Processing Polymers. Prentice-Hall, Englewood Clifts, NJ. 

At the recent European Symposium on Polymer Blends [59] about half of the contributions dealt with thermodynamic effects on molecular architecture, on polymer morphology, and on processing and performance of polymer blend materials. Although some attention has been focused mainly on the interface (material) in heterogeneous blends, in general most thermodynamic studies of such heterogeneous blends deal with two- or more bulk phases. Essential morphological features such as droplet size, cocontinuous phases, micellar or... 

In the next few years it will become clear that traditional problems with the physical properties, such as strength and durability of polymers produced by direct fluorination, are being solved largely by specific design of precursor hydrocarbon polymer morphology for the fluorination process. Polymers produced by direct fluorination have previously been satisfactory or outstanding with regard to their thermal and chemical properties. Stimulated by new efforts this field will expand rapidly. 

In the last ten years, a great deal of experimental work has been presented about the tensile properties of CNTs/polymer composites in the literature. However, it is difficult to generalize across these studies because of the large number of parameters that can influence the effective properties, including size and structure of the CNT, CNT/ polymer interaction, processing techniques and processing conditions. In this chapter, the effect of structure and morphology on the properties of the nanocomposites will be focused and discussed. 

Polymer/drug Process/solvent Nozzle id (pm) (a) CO2 (b) Drug solution (mL/min) Temperature/ pressure (°C/bar) Morphology References... 

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