摘要:

“Resins” as understood in this chapter, are three-dimensional cross -linked plastics (thermosetting resins) which cannot be processed thermoplastically once they are cured. These resins are the oldest plastics known in history and still are of great commercial importance, especially in those areas of application which require

ISSN:1532-1797    

DOI:10.1080/15321796808050892

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The term inorganic polymers comprises polymers whose main chains (linear, branched, or cross-linked) have no carbon atoms. The side groups may contain carbon. Obviously, inorganic polymers with organic side groups are particularly interesting because the physicomechanical properties required of plastics, such as plasticity, elasticity, solubility. fusibility, etc., are primarily obtained by introducing organic groups into inorganic polymer chains. In this text, reference is made to the commonly known differences between polysilicates and polysiloxanes (silicones). The great interest attached to inorganic polymers is due mainly to the search for plastics of high thermal stability. Various recent reviews summarizing the theoretical and experimental findings [G8,H6,Ll,Sl5,Y3] are available on inorganic polymers. Phosphorus-containing inorganic polymers have been included in all these monographs.

ISSN:1532-1797    

DOI:10.1080/15321796808050893

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

As outlined in Chapters 1 and 2, it is difficult to incorporate phosphorus into linear polymers by (co)polymerization or (c0)polycondensation. Only in rare cases is it possible to obtain products of high phosphorus content, high molecular weight, satisfactory mechanical properties, and satisfactory hydrolytical stability. Therefore, it is natural that the subsequent incorporation of phosphorus into commercial polymers has also been investigated. The macromolecular character of these products remains unaffected as long as no degradationof the main chain occurs. The phosphorus is always found in the side groups. The problem inherent in the subsequent introduction of phosphorus is the fact that there are only a few suitable phosphorylation reactions. Phosphorylation should be simple to carry out and should proceed rapidly even with insoluble polymers to give high yields; the incorporated phosphorus should be linked to the polymers by a stable bond, preferably a P-C bond, but above all the phosphorylation should not give rise to chain breakdown or cross-linking of the polymer. Understandably, the fulfillment of these requirements depends not only on the method of phosphorylation but also on the polymer used. Good results have been achieved so far, especially with polyolefins and polystyrene.

ISSN:1532-1797    

DOI:10.1080/15321796808050894

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Owing to the fact that sulfur can exist in different oxidation states and that in each oxidation state it can form different functions, there exist many different sulfur-containing chemical functions with a widespread array of chemical and physical properties. Consequently, sulfur-containing polymers vary from highly reactive to chemically inert substances; they can have high softening points or be viscous oils, be thermally stable or not. Some of these polymers have found commercial applications, others are of academic interest.

ISSN:1532-1797    

DOI:10.1080/15321796808050895

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The problem of the calculation of the molecular weight distribution for a polymer is an important one for the chemical engineer, since any rational attempt to tailor the properties of a polymer must eventually depend on how the various polymers are distributed in the mixture. It follows, therefore, that the rational design of a polymerization reactor requires a detailed knowledge of the rates of the almost infinite number of reactions which take place. One says almost infinite because the number may be so large that infinite mathematical processes may be utilized. There are certainly not an infinite number of species, since all species in the reaction mixture will have a finite molecular weight. In principle, if one knew the rates of all the chemical reactions taking place in the polymerization process, then for a particular reactor geometry one could predict exactly the molecular weight distribution in a batch reactor or in the effluent of a continuous reactor. One says in principle, for it may happen that the reactor geometry is such or the fluid mechanical properties of the system are such that the mathematical computations required may be so long and tedious that their being carried out is unlikely. For simple batch reactors or for simple continuous reactors the task can be carried out and has been, but for more complicated flow reactors the task is formidable.

ISSN:1532-1797    

DOI:10.1080/15321796808050896

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Initial ventures into the search for synthetic polymers were largely motivated by factors of need rather than because of a desire to have new materials with improved properties. Thus plastics were made as substitutes for relatively rare and expensive products such as ivory, while synthetic elastomers were developed as replacements for natural rubber which became virtually unavailable to a number of nations during World War 11. In the past decade, however, immense changes in science and technology have continually placed increasing stringent requirments on polymeric materials. Commercially available products have rapidly become obsolete because of their inability to withstand decomposition under a variety of environmental extremes. As a result, the emphasis of research has changed and extensive studies have been and are currently being conducted throughout the world to find new macromolecular structures that are more useful for many new applications, particularly at high temperatures. It is the purpose of this paper to review the developments in this field during the last two years, with particular consideration given to o rgano metallic and ring-containing polymers.

ISSN:1532-1797    

DOI:10.1080/15321796808050897

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

This is a scanned image of the original Editorial Board page(s) for this issue.

ISSN:1532-1797    

DOI:10.1080/15321796808050891

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor