Polymers linearity

Ketten-glied. n. link (or member) of a chain, -isomerie, /. chain isomerism, -kokken, m.pl. streptococci, -linie,/. catenary (curve), -moldktil, n. chain molecule, linear molecule, -polymer, n. chain polymer, linear polymer, -rad, n. sprocket wheel, -reaktion, /. chain reaction, -trieb, m. chain drive. 

Fig. 8. a Mark-Houwink plot for various fractions of highly branched PMMA obtained by SCVCP of MMA with the inimer 12. M unical (xlO ) = 12.06 ( ), 9.64 (O), 7.2 (A), 5.58 (V), 3.52 (0),3.26 (+),2.18 (x),2.00 ( ) (—) unfractionated feed polymer ( ) linear PMMA. b Mark-Houwink plot obtained from intrinsic viscosities of each fraction of branched PMMA. (Reproduced with permission from [88]. Copyright 2001 American Chemical Society.)... 

Fig. 7.1 Schematic representation of linear versus dendritic polymers linear (left) and hyperbranched (middle) polymers, perfect dendrimer (right). The amount of terminal groups is indicated below each structure. These architectures can also be attached to a cross-linked polymer bead to obtain a high-loading hybrid material.

Based on the results obtained to date, which have been summarized above for several different semicrystalline polymers— linear and low density (branched) polyethylene, polytrimethylene oxide, polyethylene oxide and cis polyisoprene—it is concluded that the relatively fast segmental motions, as manifested in Tq, are independent of all aspects of the crystallinity and are the same as the completely amorphous polymer at the same temperature. Furthermore, it has previously been shown that for polyethylene, the motions in the non-crystalline regions are essentially the same as those in the melts of low molecular weight ii-alkanes. (17)... 

PP bead foams of a range of densities were compressed using impact and creep loading in an Instron test machine. The stress-strain curves were analysed to determine the effective cell gas pressure as a function of time under load. Creep was controlled by the polymer linear viscoelastic response if the applied stress was low but, at stresses above the foam yield stress, the creep was more rapid until compressed cell gas took the majority of the load. Air was lost from the cells by diffusion through the cell faces, this creep mechanism being more rapid than in extruded foams, because of the small bead size and the open channels at the bead bonndaries. The foam permeability to air conld be related to the PP permeability and the foam density. 15 refs. 

The reagent stoich. fran -Ru(0)3(0Ac)3(py)3/CH3CN oxidised Ph3P to Ph3PO giving what may be Ru" (0)(OAc)(py)3 or a p-oxo bridged polymer. Linear and cyclic alkenes were epoxidised with additional by-products hydrocarbons and... 

Polyphosphazenes are the most important and the most thermally characterized of the phosphorus-containing inorganic polymers. Linear, cycloli-near, and cross-linked cyclomatic polymers based on phosphazene structures have been produced. The repeating units of some polyphosphazenes are as follows ... 

Yury V. Kissin, Mobil Chemical Company. Edison. NJ. htlp/Acwu. csxonmobilchcmical.com/. Polyethylene (under Olefin Polymers) High Density Polyethylene (under Olefin Polymers) Linear Low Density Polyethylene (under Olefin Polymers) and Polymers of Higher Olefins (under Olefin Polymers)... 

It should also be noted that, although most of the polymers discussed in this chapter are assumed to be linear open-chain structures, the possibility also exists that giant macrocyclic species or chain-linked macromolecules may also exist.1 Such species would be very difficult to distinguish from linear high polymers. Linear polymers have end groups that, in theory, might be detectable by NMR techniques, but in practice the chains are... 

If the monomers are bifunctional, as in the above example, then a linear polymer is formed. Terminating monofunctional groups will reduce the average degree of polymerisation. Polyfunctional monomers, such as glycerol and phthalic acid, are able to form branching points, which readily leads to irreversible network formation (see Chapter 9). Bakelite, a condensation product of phenol and formaldehyde, is an example of such a space-network polymer. Linear polymers are usually soluble in suitable solvents and are thermoplastic - i.e. they can be softened by heat without decomposition. In contrast, highly condensed network polymers are usually hard, are almost completely insoluble and thermoset - i.e. they cannot be softened by heat without decomposition. 

In the field of high thermomechanical performance polymers, linear and thermosetting systems offer complementary properties. Among the thermosetting materials, BMIs and BNIs have been extensively studied and are now commercially available. In this chapter, firstly the main preparation and characterization methods are reviewed, and then the chemistry of the polymerization processes is discussed for both families. For the BMIs, due to the electrophilic character of their double bond, different polymerization pathways have been published, which is not the case for BNIs. Special attention has been paid to thermal polymerization which has already been used in industrial achievements however, on the other hand, the structure of these materials has been considered for the purpose of establishing relationships between processability, stability and thermomechanical properties. 

Cross-Linked Polymer Linear polymer strands linked to each other by chemical bonds. 

Corhin PS, Zimmermann SC (2005) Hydrogen bonded supramolecular polymers linear and network polymers and self-assembhng discotic polymers. CRC press, Boca Raton, El, p 153... 

Figure 1 Macromolecular architectures linear macromolecular chains (homopolymer, block-copolymer and statistical copolymer [14]), brushed-polymer (= linear chains attached to a polymer-chain brush-polymer, brush-copolymers [14]), star polymer [4], mikto-star-polymer [16], arborescent graft polymer (=repeated grafting of linear chains on a macromolecule [17,18]), dendrimer (= maximally branched, regular polymer [15])...

Two types of new silicon-branched organosilicon polymers, linear and ladder polysilane structures, were produced from dihalo- and tetrahalodisilane, respectively, via alkali-metal-mediated reactions. Further investigations disclosed that the polymers may he useful as photoresists, semiconductors, ceramic precursors, and composite materials in high-technology fields. 

To elucidate the question whether or not cyclosilane structures are essential for the color and fluorescence of the polymers, linear and cyclic silanes with silicon halogen or -triflate functions were prepared and hydrolyzed to siloxene-like structures. 

The special property to generate very strong fibers of these polymers (particularly for Kevlar ) is probably a result of their highly uniform steric structure. In a polyamide such as nylon 6, the substituents at the amide group may take a cis or trans position, which disturbs the polymer linearity as shown below ... 

Gelation processes, such as crosslinking linear chains or condensation of /-functional monomers A/ (where A reacts with A) with /> 2 are quite different from either linear condensation polymers or hyperbranched polymers. Linear condensation polymers (made from AB monomers, -where A only reacts with B) and hyperbranched polymers (made from... 

One of the biggest choices made in selecting a DMA is to decide whether to choose stress (force) or strain (displacement) control for applying the deforming load to the sample. Because most DMA experiments run at very low strains ( 0.5% maximum) to stay well within a polymers linear region, both analyzers give the same results. 

J.P. Hogan, Olefin polymers—linear (high-density) polyethylene, in M. Grayson, D. Eckroth (Eds.), Kirk-Othmer Encyclopedia of Chemical Technology, vol. 16, third ed., Wiley, New York, 1981, pp. 421M33. 

As a rule, the combination of high protein surface charge density, high polymer linear charge density of opposite sign, and low ionic strength promotes precipitation rather than coacervation. The similitude with ionic micelle/... 

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