S U M M A R Y :It is shown that the presently available information on the structure of bulk amorphous polymers is consistent with the concept of the existence of a substantial amount of short-range segmental order. It is suggested that the sharp change of molecular-weight dependence of NEwToNian viscosity of polymer melts with the approach to the critical "entanglement" molecular weight M , is brought about mainly by the transition from the extended-chain conformation of the macromolecules into the statistically folded-chain conformation. Finally, empirical relationships are obtained which relate the values of polymer packing coefficients in the crystalline state as well as the "best" numerical values of M , with molecular parameters of a polymer. Z U S A M M E N F A S S U N G :Es wird gezeigt, daR die zur Zeit vorhandenen Kenntnisse iiber die Struktur von amorphen Blockpolymeren mit der Vorstellung von der Existeaz eines betrachtlichen Anteils an Nahordnung der Kettensegmente iibereinstimmen. Es w i d vermutet, daR die starke Veranderung der Molekulargewichtsabhangigkeit der NEwToNschen Viskositat von Polymerenschmelzen beim Erreichen eines kritischen Molekulargewichts M , fur die Bildung von ,,Verhakungen" hauptsachlich bedingt ist durch den Ubergang von Makromolekiilen aus der gestreckten Konformation in eine solche mit statistischen Faltungen der Makromolekule. SchlieRlich werden empirische Abhangigkeiten 'ermittelt, welche die Werte der Packungskoeffizienten eines Polymeren im kristallinen Zustand sowie die ,,besten" numerischen Werte von M , mit molekularen Parametern eines Polymeren verbinden.
The problem of deriving polymer alloys and blends and of modifying the properties of polymer by introducing small amounts of other polymers therein is presently of interest from the standpoint of producing polymeric materials with improved and new characteristics without synthesizing new polymers.The formation of polymer blcnds is a typical process of developing a colloidal heterogeneous system wherein the interphase phenomena occurring at the interface are quite important. Such systems can be considered to be dispersed colloidal systems on the basis that in most cases one of the components attains a colloidal degree of dispersity which may be regardes as a dispersed phase within the medium of the other component of the dispersion medium. Polymer blends are characterized by a two-phase structure which can be represented either in the form of a typical colloidal system or as a system in which both the phases are continuous, and one of them cannot be distinguished as a dispersion medium nor the other as a dispersed phase. The latter phenomenon is typical of blends comprising approximately equal amounts of both components, whereas in the region with small amounts of one of the components the system is typically colloidal. Phase inversion, well known for emulsions and occurring with a change in the ratio of components in a system, is typical for polymer blends as well. However there are specific features which distinguish polymer blends as heterogeneous colloidal systems from systems studied in classical colloid chemistry. These include the formation of a transition or intermediate layer between the two components which is due to the effect of a number of thermodynamic and kinetic factors. This interphase layer in many respects determines the physical and mechanical properties of polymer blends.Some theoretical concepts about polymer-polymer interphase in incompatible polymers were developed by Helfand [ 1,2] on the basis of conformational statistics of polymer chains.In this report attempts will be made to experimentally substantiate a colloid-chemical approach to polymer blends. The basic concept here is that polymer blends in an overwhelming majority of cases are devoid of the true solubility of one component in the other or of thermodynamic compatibility which is determined by the decrease in the free energy of mixing [3]. Many findings indicate that the solubility of polymers in one another or of polymer in oligomers is a rare occurrence and can be realized only within a very narrow region of compositions and temperatures. A reduction of compatibility due to a change in temperature
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