Polymer chains, bridges

Fig. 1 Schematic representation of a bundle and a bundle aggregate in a polymer chain. Bridges, loops, and crystallized stems are evidenced...

At lower surface coverage, however, tire possibility exists that one polymer chain may attach itself to two particles. If tire adsorjDtion is strong enough, tliis results in an aggregation of tire particles, known as bridging flocculation [33,46, and 47],... 

The second step is a condensation reaction that involves the linking together of monomer units with the Hberation of water to form a dimer, a polymer chain, or a vast network. This is usually referred to as methylene bridge formation, polymerization, resinification, or simply cure, and is illustrated in the following equation ... 

The vulcanizing agent, which supplies the bridge between the polymer chains, is stiU furnished predominantly by the sulfur molecule in commercial... 

The softening behaviour of a thermoplastic material depends to a large extent on the flexibility of the chain and the ability to crystallise. Significant cross-linking of a reasonably stiff-chained polymer will lead to material that is unlikely to soften below its decomposition temperature. Intermediate to the linear and cross-linked polymers are various ladder polymers in which the polymer molecule consists of a pair of more-or-less parallel chains bridged in a manner analogous to the rungs of a ladder. 

Another model assumes that gel zones are formed by hydrated lead dioxide (PbO(OH)2) and act as bridging elements between the crystallite particles. Electrons can move along the polymer chains of this gel and so cause electronic conductivity between the crystalline zones 137],... 

Flocculation involves large polymer chain molecules adsorbing onto more than one particle, causing bridging. Typically, this process is carried out over a period of 20 to 30 minutes with gentle... 

The mechanism of adhesion to various substrates has not been fully explained. Brauer Stansbury (1984b) consider that bonding to composite resins occurs by the diffusion of methacrylate polymer chains into the resin. Bonding to base metals is, perhaps, by salt or chelate bridges. Here it is significant that ZOE cements do not bond, so perhaps bonding is due to the action of free EBA on the substrate. The adhesion to porcelain is surprising. Porcelain is inert so that the attachment can hardly be chemical. Also, it would be expected that if a cement adheres to porcelain then it should adhere to untreated enamel and dentine, but this is not so. 

In this sense, similar to other contributions in this volume, we will attempt to bridge the gap from microscopic to mesoscopic and thereafter to the semimacroscopic [45] regime within a simulation scheme. Firstly, we will describe in detail a mapping procedure to go from a microscopic description of a polymer chain to a mesoscopic description which allows a fairly effective simulation procedure on a coarse-grained level [43]. The choice of three modifications of one polymer... 

Fig. 17. Proposed structure of the PVA-polyiodide inclusion compound. The polymer chain is shown as a helical line with appended hydroxyl groups and bridging borate groups. The stippled core represents the polyiodide guest chain...

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