Addition polymer, definition

Within the scope of the original definition, a very wide variety of ionomers can be obtained by the introduction of acidic groups at molar concentrations below 10% into the important addition polymer families, followed by partial neutralization with metal cations or amines. Extensive studies have been reported, and useful reviews of the polymers have appeared (3—8). Despite the broad scope of the field and the unusual property combinations obtainable, commercial exploitation has been confined mainly to the original family based on ethylene copolymers. The reasons for this situation have been discussed (9). Within certain industries, such as flexible packaging, the word ionomer is understood to mean a copolymer of ethylene with methacrylic or acryhc acid, partly neutralized with sodium or zinc. 

The difficulties of devising a basis for conveniently classifying various polymerizations in an appropriate manner have been discussed earlier in this chapter and several borderline examples which offer particular difficulty have been mentioned. One of these, the polymerization of the N-carboxyanhydrides, falls within the definition of a condensation polymerization, proceeds by a mechanism resembling a vinyl addition polymerization, and yields a product which possesses the structure of a typical condensation polymer. Definitions have been... 

If the elemental formula of the structural unit of a polymer is known, the molar mass per structural unit can be calculated directly by addition (=summation) of the atomic masses. The molar mass is the oldest Additive Function it is additive by definition, since it is based on a fundamental law of chemistry the law of "Conservation of mass". 

The polyamide made from caprolactam is technically an addition polymer by the above definition, while the product made from the amino acid would be a condensation polymer. Actually, only the caprolactam synthesis is used commercially, and the product (polycaprolaclam = nyIon-6) is called a condensation polymer because all polyamides are so classified. 

Polymers made by chain-growth reactions are often addition polymers by Carothers s definition. The most common polymers made by these processes have only carbon-carbon links in their backbones. 

In this review dealing with recent advances in membrane science, the term membrane" will be used to indicate any medium which acts as a barrier to transport into or out of a region, provides selective transfer of one species over another or regelates the transport of a material to its environment at a controlled rate. In addition to the common usage of the word membrane" to indicate a dense polymer film, the above definition includes a variety of interesting cases such as highly porous ultrafiltration membranes and hydrophobic liquid membranes with selectivity properties which can be tailored by incorporation of materials which selectively complex with one of the species to be processed. The important topics of controlled release of chemicals from polymeric devices and removal of volatile monomers from addition polymers such as poly (vinyl chloride and poly (acrylonitrile are also treated here. 

To overcome such problems, an alternative definition has been introduced. According to this definition, polymers whose main chains consist entirely of C-C bonds are classified as addition polymers, whereas those in which heteratoms (O, N, S, Si) are present in the polymer backbone are considered to be condensation polymers. A polymer which satisfies both the original definition (of Carothers) and the alternative definition or either of them, is classified as a condensation polymer. Phenol-formaldehyde condensation polymers, for example, satisfy the first definition but not the second. 

In 1929 Carothers suggested a separation of all polymers into two classes, condensation and addition polymers. By condensation polymers he defined those polymers that lack certain atoms from the monomer units from which they were formed or to which they may be degraded by chemical means. He also defined addition polymers as polymers with identical structures of the repeat units to the monomers from which they are derived. Thus, according to the above definition, an example of a condensation polymer can be a polyamide formed by condensing a diacid chloride with a diamine and splitting off hydrochloric acid ... 

Also, according to the above definition, an example of an addition polymer can be polystyrene that is formed by addition of styrene monomers ... 

Definition Addition polymer of ethylene oxide and methanol... 

Definitions. Define and illustrate the following terms (a) monomer, (b) polymer, (c) copolymer, (d) tetramer, (e) addition polymer, (f) condensation polymer, (g) ion-exchange resin, (h) protein, (i) enzyme. 

In the early distinction by Carrothers (1) between condensation and addition polymers, polyesters were uniformly considered as examples of the former. However it was soon appreciated that a large family of polymers could be made which were functionally "polyesters" but did not fall into the synthesis based definition of condensation polymers. This family of polymers are usually prepared by ionic routes, generally a ring opening polymerization, and are structurally different from the condensation polyesters by having a chain sense i.e. the crystalline chain conformation possesses an intrinsic dipole moment. Accordingly, a structurally based definition of polyesters in terms of "polar and non-polar" crystalline conformations will be used in this report. The non-polar molecules considered will be aromatic polyesters and the polar molecules will be polyalkanoates. 

The double bond opens up, forming bonds to other monomers at each end, so a carbon-carbon double bond is difunctional according to our general definition. (Note that a monomer with two double bonds has a functionality of four this type of monomer is often referred to as a cross-linking agent as it results in the formation of network structures.) The question of what happens at the ends of addition polymers will be deferred until we reach Chapter 9 on polymerization mechanisms. Also, note that carbon-oxygen double bonds, while common in monomers and polymers, are stable and unreactive for addition polymerization. 

In the polymer literature each of the five quantities listed above is encountered frequently. Complicating things still further is the fact that a variety of concentration units are used in actual practice. In addition, lUPAC terminology is different from the common names listed above. By way of summary, Table 9.1 lists the common and lUPAC names for these quantities and their definitions. Note that when

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A plasticizer is a substance the addition of which to another material makes that material softer and more flexible. This broad definition encompasses the use of water to plasticize clay for the production of pottery, and oils to plasticize pitch for caulking boats. A more precise definition of plasticizers is that they are materials which, when added to a polymer, cause an increase in the flexibiUty and workabiUty, brought about by a decrease in the glass-transition temperature, T, of the polymer. The most widely plasticized polymer is poly(vinyl chloride) (PVC) due to its excellent plasticizer compatibility characteristics, and the development of plasticizers closely follows the development of this commodity polymer. However, plasticizers have also been used and remain in use with other polymer types. 

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