Structure chain

This chapter focuses on supply chain structure and ownership, one of the Cs in the supply chain framework. The chain structure is the backbone or the pipeline through which information and material flow in the supply chain. It is the process map of a supply chain that typically crosses many independent company boundaries. Once a supply chain map is generated, the location of entities, as well as ownership, and the connections to the rest of the supply chain architecture influence the observed lead times, costs, incentives, and thus performance, of the supply chain. 

Our goal in this chapter is to understand commonly observed supply chain structures and discuss their potential impact on performance. Key supply chain features include the number of links in the chain, the locations where capacity is shared, the level of flexibility of the entities and their impact, the impact of chain structure and capacity, the impact of uncertainty on performance of the network and finally, how country boundaries interact with flows across the chain. 

The following are commonly used supply chain structures. 

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The hydrides of beryllium and magnesium are both largely covalent, magnesium hydride having a rutile (p. 36) structure, while beryllium hydride forms an electron-deficient chain structure. The bonding in these metal hydrides is not simple and requires an explanation which goes beyond the scope of this book. 

The silanols formed above are unstable and under dehydration. On polycondensation, they give polysiloxanes (or silicones) which are characterized by their three-dimensional branched-chain structure. Various organic groups introduced within the polysiloxane chain impart certain characteristics and properties to these resins. 

The high molecular weight of a polymer is one of the most immediate consequences of the chain structure of these molecules. As indicated in Sec. 1.2, it is also the basis for describing the size of the polymer molecule, either directly or through the degree of polymerization. Most methods for the determination... 

In this chapter we examine the flow behavior of bulk polymers in the liquid state. Such substances are characterized by very high viscosities, a property which is directly traceable to the chain structure of the molecules. All substances are viscous, even low molecular weight gases. The enhancement of this property due to the molecular structure of polymers is one of the most striking features of these materials. 

In this chapter we examine the elastic behavior of polymers. We shall see that this behavior is quite different from the elasticity displayed by metals and substances composed of small molecules. This is a direct consequence of the chain structure of the polymer molecules. In many polymers elasticity does not occur alone, but coupled with viscous phenomena. The combination of these effects is called viscoelasticity. We shall examine this behavior as well. 

Chain Structure. LLDPE resins are copolymers of ethylene and a-olefins with low a-olefin contents. Molecular chains of LLDPE contain units derived both from ethylene, —CH2—CH2—, and from the a-olefin, —CH2—CHR—, where R is C2H for ethylene—1-butene copolymers, for... 

Chain Structure. The chemical composition of poly (vinyhdene chloride) has been confirmed by various techniques, including elemental analysis, x-ray diffraction analysis, degradation studies, and in, Raman, and nmr spectroscopy. The polymer chain is made up of vinyhdene chloride units added head-to-tail ... 

This will lead initially to branched chain structures such as indicated schematically in Figure 2.10, G indicating a glycerol residue and P a phthalic acid residue. In due course these branched molecules will join up, leading to a cross-linked three-dimensional product. 

In the first case, that is with dipoles integral with the main chain, in the absence of an electric field the dipoles will be randomly disposed but will be fixed by the disposition of the main chain atoms. On application of an electric field complete dipole orientation is not possible because of spatial requirements imposed by the chain structure. Furthermore in the polymeric system the different molecules are coiled in different ways and the time for orientation will be dependent on the particular disposition. Thus whereas simple polar molecules have a sharply defined power loss maxima the power loss-frequency curve of polar polymers is broad, due to the dispersion of orientation times. 

The suppliers of nylon 46 have laid particular emphasis on the fact that this polymer, with its highly symmetrical chain structure, leads to both a high level of crystallinity and a high rate of nucleation. In turn the high nucleation rate leads to a fine crystalline structure which in this case is claimed to lead to a higher impact strength (dry as moulded) than with nylons 6 and 66. 

Effect of chain structure on the hydrolysis of polyester polyurethanes... 

Polymers which already have a long chain structure may provide a good floe at low mixing rates. Often the turbulence and detention in the clarifier inlet distribution is adequate. 

There are notable differences in both structures and stabilities for binary N-O and S-N anions (Section 5.4). The most common oxo-anions of nitrogen are the nitrite [N02] and the nitrate anion [NOs] the latter has a branched chain structure 1.1. The sulfur analogue of nitrite is... 

Figure 4.6 (a) The double-chain structure of LiOH.HiO, and (b) the layer structure of anhydrous LiOH (see text). 

BeCl2 has an unusual chain structure (a) which can be cleaved by weak ligands such as Et20 to give 4-coordinate molecular complexes L2BeCl2 (b) stronger donors such as H2O or NH3 lead... 

The triphenyl analogues are also monomeric in solution but tend to associate into chain structures in the crystalline state as a result of weak interraolecular M---C interactions GaPhr mp... 

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