Polymer general aspects

QUALITATIVE AND QUANTITATIVE INFORMATION ON POLYMERS - General aspects... 

K. Binder. General aspects of computer simulation techniques and their applications in polymer physics. In K. Binder, ed. Monte Carlo and Molecular Dynamics Simulations in Polymer Science. New York Oxford University Press, 1995, pp. 3 1. 

General aspects of chain transfer have been reviewed by Chiefari and Rizzardo,3 Barson, 1 Farina/ Fastmond6 and Palit el al1 The use of chain transfer in producing lelechelic and other functional polymers has been reviewed by Boutevin,8 Heitz/ Comer10 and Starks11 and is discussed in Section 7.5.2. There are two main mechanisms which should be considered in any discussion of chain transfer (a) atom or group transfer by homolytie substitution (Section 6.2.2) and (b) addition-fragmentation (Section 6.2.3). 

For general aspects on sonochemistry the reader is referred to references [174,180], and for cavitation to references [175,186]. Cordemans [187] has briefly reviewed the use of (ultra)sound in the chemical industry. Typical applications include thermally induced polymer cross-linking, dispersion of Ti02 pigments in paints, and stabilisation of emulsions. High power ultrasonic waves allow rapid in situ copolymerisation and compatibilisation of immiscible polymer melt blends. Roberts [170] has reviewed high-intensity ultrasonics, cavitation and relevant parameters (frequency, intensity,... 

General Aspects of Dendritic Polymers and Solid-phase Hybrid Polymers... 

The reader will find no description of the many individual polymers studied. I have preferred to give major emphasis to the general aspects of the subject, illustrated in each instance by a few chosen examples. 

Fontanille, M., Carbanionic Polymerization General Aspects and Initiation, pp. 365-386 and Carbanionic Polymerization Termination and Functionalization, pp. 425 432 in Comprehensive Polymer Science, Vol. 3, G. C. Eastmond, A. Ledwith, S. Russo, and P. Sigwalt, eds., Pergamon Press, London, 1989. 

Because of its chemical and practical significance, polymerization is exhaustively reviewed and excellent monographs,114-129 a multivolume encyclopedia,130 as well as the series Advances in Polymer Science,131 cover all aspects of the field. Consequently, our aim is not a comprehensive treatment, but to discuss the most important general aspects of the major types of polymerization of unsaturated hydrocarbons and to give selected examples of practical significance. 

The hydrolysis introduces all of the oxygen into the silicon oxide matrix, i.e. all of the oxygen comes from the water molecules. The underlying details of the chemistry are extremely complex12-14 and the detailed description of mechanistic studies is beyond the scope of the topic of this chapter, except for mechanistic studies which involve organic molecules and polymers — these are given in the various sections below. Here, some general aspects are summarized. 

Before describing 129Xe NMR experiments on polymers and polymer composites, it is worthwhile to show with a few selected examples, some of the general aspects of 129Xe NMR of polymers. The first question that needs to be addressed is where sorbed Xe atoms are located in a polymer material, or rather where Xe atoms are not located. With a diameter of 0.44 nm the Xe atom is clearly larger than the interchain distance for most crystalline polymers. In general it means, that if Xe atoms are found in crystalline domains, they must reside in areas which contain defects. In the examples studied, no evidence of Xe in crystalline domains of polymers was ever found. 

Of course, some general aspects of our treatment could be easily extended to a general form of f b ireJ as in the semi-infinite case [226],but for explicit numerical work a specific form of fs(b ire) ((()) is needed. Equation (10) can be justified for Ising-type lattice models near the critical point [216,220], i.e. when ( ) is near ( >crit=l/2, as well as in the limits f]>—>0 or <()—>1 [11]. The linear term —pj( ) is expected due to the preferential attraction of component B to the walls, and to missing neighbors for the pairwise interactions near the walls while the quadratic term can be attributed to changes in the pairwise interactions near the walls [144,216,227]. We consider Eq. (10) only as a convenient model assumption to illustrate the general theoretical procedures - there is clear evidence that Eq. (10) is not accurate for real polymer mixtures [74,81,82,85]. 

The general aspects of ignition, combustion and extinction in polymeric materials have been considered. There is a relationship between the chemical nature of the polymer and its flammability, which can be estimated from the influence of the polymer structure on the stoichiometry and the specific heat of the combustion reaction. 

This article highlights the utilization of hydrogen bonds for the controlled assembly of nanoparticles and polymers both in solution and on substrates. While an extensive discussion of polymer and nanoparticle synthesis is beyond the scope of this article and has been reviewed in other places [31-33], we will discuss here the general aspects pertaining to the design and control of hydrogen-bonding mediated polymer-nanoparticle assemblies and the... 

Fracture Mechanics describes the behavior of sharp cracks in loaded materials and thus enables to characterize the strength of materials and components. Since Griffith s early considerations and Irwin s basic work, fracture mechanics has been systematically developed and has now reached a high level of sophistication. Correspondingly, there is extensive literature on the subject and the interested reader should consult, for example. Ref. for general aspects of the subject or Refs. for specific considerations of polymer fracture. The present... 

Classical theories of emulsion stability focus on the manner in which the adsorbed emulsifier film influences the processes of flocculation and coalescence by modifying the forces between dispersed emulsion droplets. They do not consider the possibility of Ostwald ripening or creaming nor the influence that the emulsifier may have on continuous phase rheology. As two droplets approach one another, they experience strong van der Waals forces of attraction, which tend to pull them even closer together. The adsorbed emulsifier stabilizes the system by the introduction of additional repulsive forces (e.g., electrostatic or steric) that counteract the attractive van der Waals forces and prevent the close approach of droplets. Electrostatic effects are particularly important with ionic emulsifiers whereas steric effects dominate with non-ionic polymers and surfactants, and in w/o emulsions. The applications of colloid theory to emulsions stabilized by ionic and non-ionic surfactants have been reviewed as have more general aspects of the polymeric stabilization of dispersions. ... 

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