Branching Types

So far, all we have considered in terms of chain microstructure is the difference between linear and branched homopolymers. In the rest of this chapter we will introduce other types of microstructures, but as we go along we want you to keep in mind some of the quick and dirty arguments we gave concerning the relationship of chain structure to long-range order (crystallinity) and, hence, physical properties. Ask yourself, Would a chain with this microstructure be capable of crystallizing, and if it did, what would that mean in terms of properties  

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In recent years poly(malic acid) has been discovered in several fungal strains, notably in Physarum polyceph-alum [4] and in Aureobasidium sp. [5,6], and have been analysed as being of the j8-type(II) either linear (P. poly-cephalum) or branched (type IV) Aureobasidium sp.). 

Branched types. These are dextrans which are composed entirely of a-linked... 

The isomerization of 5 to 7 and 8 involves a chain-branching type rearrangement (lOis ll) (Brouwer and Oelderik 1968) and has a free-enthalpy of activation of about 22 kcal mole . This result, combined with the data of Fig, 2, the free-enthalpy of activation of 17 kcal mole for the rearrangement 9-i ll (Brouwer and Hogeveen, 1972), and an estimated difference in free-enthalpy of about 0-8 kcal mole between 10 and 11 constitutes the basis for the free-enthalpy diagram in Fig. 3. 

Dendritic Poiyrotaxanes Incorporating Ring Components on the Branches Type lll-A... 

Polyalkyleneimines are polyamines whose structure is classified into linear and branched types as shown below. 

Schmidt So you don t know how generalizeable the mechanism is to asymmetric division in lungs or other branching-type structures ... 

Another important issue is the difference between various branching types such as random hyperbranched [31], dendrigrafts and dendrimers. The complexity of synthesis requirements manifested by the statistical dendritic polymers versus the more structurally controlled dendrimers could make the former orders of magnitude more expensive than hyperbranched. Are the structures as significantly unique and of sufficient value effectiveness to justify the higher costs ... 

Figure 9. Relative scission efficiencies of short-chain branches in the 7 radiolysis of ethylene-a-olefin copolymers. Branch types are indicated.

The algal polysaccharides resembled the relatively simplified structures of tile neutral mucilages, as in the case of carrageenan A wider spectrum of struclures is found in Ihc bacterial gums, which arc generally of the highly branched type exuded by higher plants,... 

The nature of the protecting groups employed in the preparation of disaccharide discussed above does not permit the extension of the synthesis to the branched type of KDO trisaccharide shown in Fig. 1. To obtain another model compound for the structure elucidation of the natural KDO trisaccharide by spectroscopic and immunochemical methods, a route was devised which would permit the synthesis of the model trisaccharide 12. 

Branching disturbs the chain regularity if the branches are situated at random positions along the chain. In particular with PE a number of branching types... 

On the purely macroporous substrate, multilayer formation takes place in the adsorption run, whereas capillary condensation only occurs at relative pressures near unity. The desorption follows the adsorption branch (type II isotherm in the BET classification). 

Polyironphenylsiloxane, as well as polyalumophenylsiloxane, is a polydis-perse mixture of macro chains of ladder type I and branched type II structure. 

The Dnieper delta is of the filling or bayhead and multi-branch type (Fig. 9). An area and a length of the delta equal to 350 km2 and 47 km cor-... 

The Don delta belongs to the filling (or bayhead) and multi-branch type (Fig. 13). 

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