Polymer classes

Because the chemical stmcture of poly(phenylene sulfide) [9016-75-5] (PPS) does not fall into any of the standard polymer classes, the Federal Trade Commission granted the fiber the new generic name of Sulfar. The fiber has excellent chemical and high temperature performance properties (see... 

CLAIMS COMPREHENSIUE (subscriber access only) further enhances the UNITERM indexing from 1964 with roles for aH iadexed compounds and polymer class terms and with links and negation codes for the fragment terms describiag chemical compounds (94). 

The chemistry and technology of this class of polymer may be considered as an extension to those of the polysulphones, particularly insofar as there are strong parallels in preparative methods. The two polymer classes also have strong structural similarities with polysulphones containing the structure (I) and the polyetherketones the structure (II) of Figure 21.6. 

It is the intent of the present chapter to review the chemistry of the significant PSA polymer classes and discuss their application to tape and related products. 

Architectural Polymer Class Polymer Type Repeat Units Covalent Connectivity ... 

The Wiley Series in Polymer Science aims to cover topics in polymer science where significant advances have been made over the past decade. Key features of the series will be developing areas and new frontiers in polymer science and technology. Emerging fields with strong growth potential for the twenty-first century such as nanotechnology, photopolymers, electro-optic polymers etc. will be covered. Additionally, those polymer classes in which important new members have appeared in recent years will be revisited to provide a comprehensive update. 

To start with, the reader may have noticed that all the quoted advantages are never combined together in the same polymer class. Moreover, polymers meet certain general obstacles as technical materials. Let us quote for example sensitivity to impact, ageing, low rigidity, thermal behaviour, rate of production, recycling. 

Item Polymer Class Sperm Penetration in Cervical Mucus (% of Control)... 

Blending of the lowest price commodity polymers from synthetic and carbohydrate polymer families [e.g., poly(ethylene) and starch] would appear to follow these laws. Although each polymer class is produced in large volume (first law), the production rate for com starch/synthetic polymer blends is much lower than that for the synthetic polymer this slower extrusion rate directly affects the final cost. Ignoring this limitation, the film properties of the blend are significantly poorer than those of the synthetic polymer film. Both deficiencies are related to the poor thermoplastic properties of water-soluble polymers such as cora-starch. 

The same publication [2] recommended a generic source-based nomenclature, which comprises the optional addition of a polymer class name to the source-based name of the polymer. The addition is recommended when it is necessary to avoid ambiguity or to add clarification. 

A generic source-based name of a polymer has two components in the following sequence (1) a polymer class (generic) name (polyG) followed by a colon and (2) the actual or hypothetical monomer name(s) (A, B, etc...), always parenthesized in the case of a copolymer. In the case of a homopolymer parentheses are introduced when it is necessary to improve clarity. 

Note 1 The polymer class name (generic name) describes the most appropriate type of functional group or heterocyclic ring system. 

Polymer class names relevant only to the main chain are specified in the name names of side-chain functional groups may also be included after a hyphen if they are formed during the polymerization reaction. 

Olefins or alkenes are defined as unsaturated aliphatic hydrocarbons. Ethylene and propylene are the main monomers for polyolefin foams, but dienes such as polyisoprene should also be included. The copolymers of ethylene and propylene (PP) will be included, but not polyvinyl chloride (PVC), which is usually treated as a separate polymer class. The majority of these foams have densities <100 kg m, and their microstructure consists of closed, polygonal cells with thin faces (Figure la). The review will not consider structural foam injection mouldings of PP, which have solid skins and cores of density in the range 400 to 700 kg m, and have distinct production methods and properties (456). The microstructure of these foams consists of isolated gas bubbles, often elongated by the flow of thermoplastic. However, elastomeric and microcellular foams of relative density in the range 0.3 to 0.5, which also have isolated spherical bubbles (Figure lb), will be included. The relative density of a foam is defined as the foam density divided by the polymer density. It is the inverse of the expansion ratio . 

Liu and Zhong introduced a number of QSPR models based on molecular connectivity indices [151, 152], In a first iteration, the researchers developed polymer-dependent correlations descriptors were calculated for a set of solvents and models were developed per polymer type [151], Polymer classes under consideration were polystyrene, polyethylene, poly-1-butene, poly-l-pentene, poly(4-methyl-l-pentene), polydimethylsiloxane, and polyisobutylene. As the authors fail to provide any validation for their models, it is difficult to asses their predictive power. In a subsequent iteration and general expansion of this study, mixed and therefore more general models based on the calculated connectivity indices of both solvent and polymers were developed. While it is unclear from the paper which polymer representation was used for the calculation of the connectivity indices, the best regression model (eight parameter model) yields only acceptable predictive power (R = 0.77, = 0.77, s = 34.47 for the training set, R = 0.75... 

Apart from the all-carbon backbone, poly(vinyl ester)s also exhibit a unique 1,3-diol structure (see Fig. 1). This structure is a common motif in many natural materials, e.g. carbohydrates. A number of oxidative or reductive electron transfer processes catalysed by natural redox systems are imaginable for this motif. The 1,3-diol structure is unique for a synthetic polymer and cannot be found in any other synthetic polymer class of significance. This explains the unusual biodegradation properties discussed below. 

It is important to mention that the structure/properties relationships which will be discussed in the following section are valid for many polymer classes and not only for one specific macromolecule. In addition, the properties of polymers are influenced by the morphology of the liquid or solid state. For example, they can be amorphous or crystalline and the crystalline shape can be varied. Multiphase compositions like block copolymers and polymer blends exhibit very often unusual meso- and nano-morphologies. But in contrast to the synthesis of a special chemical structure, the controlled modification of the morphology is mostly much more difficult and results and rules found with one polymer are often not transferable to a second polymer. 

Aromatic units Temperature-stable Polymer class bond... 

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