Molecular weight distribution polymer morphology

The mechanical properties (e.g., hardness, flexibility, impact resistance, abrasion resistance, and scratch resistance) of polymers are primarily characterized by the polymer molecular weight and molecular weight distribution, polymer morphology (e.g., semicrystalline and amorphous structures), and crosslinking reactions. The purpose of this section is to give the reader an introductory background about the important factors that affect the physical properties of emulsion polymers. 

Synthetic polymers are found in such a large variety of products that they have shaped modern life. The extraordinary versatility of the polymer materials in terms of properties is due to the variety and complexity of the polymer microstructure (chemical composition, chemical composition distribution, molecular weight distribution, polymer architecture, chain configuration and phase morphology). 

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]. 

In the case of failure of a pipe made of polymeric material, the determination of Tg and 7m by thermochemical methods to ascertain the effects of thermal effects, determination of molecular weight and molecular weight distribution of the polymer, morphology of the sample or structure such as crystallinity and amorphous nature help to establish the cause of failure. 

The molecular weight distribution of the polymer can have a dramatic effect on rates of depolymerisation. This effect has been demonstrated for a number of polymers, where a critical lower limit must be present before the process will start. The molecular origin for this effect is still subject to speculation, and has been attributed to a range of causes such as changes in enzyme accessibility, chain flexibility, fits with active sites, crystallinity or other aspects of morphology. 

Mechanical properties of a polymer depend on many variables— molecular weight, molecular weight distribution, morphology, additives, temperature, time, and so on. Mechanical properties of polymers are... 

This survey of the pharmaceutical aspects of polymers and macromolecules emphasises their use in formulation. It stresses the key features of polymers - their molecular weight distribution and their versatility in terms of their morphology, crystallinity, solubility and performance. 

There is a need to evaluate, by newer thermal analysis instrumentation and techniques, polymers previously only briefly characterized, emphasizing those products which show potential industrial application or other meritorious property. Such products should be well characterized with regard to such factors as chain length, molecular weight distribution, endgroup, purity, nature and amount of impurities, and actual morphological structure of the polymer. 

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