SynopsisThe diffusion of nonionic penetrant, m-nitroaniline, into polyacrylonitrile wm studied in detail on a range of temperature from 50.6"C to 95.0"C. The penetrant distribution in polymer is Fickian, which is different from that of cationic dye, Malachite Green reported earlier. The sharp inflection point (72°C) of the Arrhenius plot, log D versus 1/T, corresponds to T, of polyacrylonitrile in the presence of water, which is lower than that measured in the dry state by a dynamic mechanical testing method. The activation energy is constant below T, (ca. 10 kcal/mole), suddenly reaches a maximum a t T,, and then gradually decreases with increasing temperature. General trends of Arrhenius plot for different polymer-penetrant systems are discussed. The temperature dependence of penetrant diffusion above T, can be described by a general form of the WLF equation, log U T = log ( D T~/ D T ) = -Clg(T -T,)/(CF + T -To), where the values of C~gand C; g were calculated to be 4.03 and 24.54, respectively. A comparison was made between m-nitrcaniline and Malachite Green. The difference in the respective T, and the constants Clg and C@ of the WLF equation in polyacrylonitrile is attributed to the size of the penetrants and their ionic character. The surface concentration increases below T, and decreases above T, with rise in temperature.The diffusion coefficient D increases with the rise of temperature.
This paper was read a t the Annual Meeting of the Society of Fiber Science and Technology, Japan, held on 27th May, 1968.
252Crystallization of A-B-A Type Block Copolymers pros.) in quadratischen Plattchen kristallisieren, ahnlich denen der Polyathylenoxideinkristalle. Elektronenmikroskopische Aufnahmen dieser Kristalle zeigten, daB die Poly-arnethylstyrol-Ketten aus dem kristallinen Teil ausgeschlossen und wahrend der Kristallisation auf der Oberflache der Einkristalle abgeschieden werden. So bilden sich laoge Sehlaufen, die in der Losung oder beim Trocknen der Kristalle aggregieren, je nach den angewandten Losungsrnitteln. Wenn man die Konzentration des Polymeren auf 0,5 yo erhoht, bilden sich unregelmaBig geformte, mehrschichtige Kristalle, an deren Oberflache eine Anzahl von Lochern gefunden wird, was zur Annahrne fiihrt, daB die Haufigkeit des Vorkommens von Molekiilen, die mehrere Schichten miteinander vernetzen, rasch mit ansteigender Konzentration steigt.Es werden experimentelle Unterlagen fur die Bildung von langen Schlaufen auf der Oberflache der lamellaren Kristalle und von molekularen Verbindungen zwischen den einzelnen Lamellen bei der Kettenfaltungskristallisation geliefert.
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