The glass transition in styrene‐based ionomers was investigated by means of infrared spectroscopy and differential scanning calorimetry (DSC). Transition temperatures were determined from the temperature dependence of the peak absorbances of the 1700 and 1745 cm−1 bands. These transition temperatures agreed with glass transition temperatures (Tg) determined by DSC. With increasing degree of ionization, Tg and the enthalpy ΔH of the residual intermolecular hydrogen bonding increased. The values of Tg obtained were analyzed by the theory of Fox and Loshaek for the effect of crosslinks. It is concluded that sodium ions probably from ionic domains and act as crosslinks to reinforce the residual hydrogen bonding and may increase Tg. The absorbance at 1560 cm−1 (νCOO−) did not change at Tg. This suggests that the glass transition observed here is not due to the onset of the mobility in ionic domains, as has been proposed for ethylene‐based ionomers on the basis of dielectric measurements.
Radiation‐induced copolymerization of tetrafluoroethylene with propylene was carried out at low temperature in the liquid phase. The resulting copolymers were found to range from viscous oils to rubberlike materials, depending on the polymerization conditions. It was observed that there are induction periods in these copolymerizations, and that the rate of copolymerization is proportional to the square root of the dose rate. Fluorine contents of the copolymers were determined, and the monomer reactivity ratios in the copolymerization were found to be rC3H6 = 1.0 and rC2F4 = 0.06. The viscosity of the copolymer was measured in tetrahydrofuran at 30°C. Infrared spectra of the copolymers were also measured. It was concluded from these experimental results that the copolymerization proceeds by a radical mechanism.
A second-order transition of cellulose triacetate at approximately 30°C was studied by polarized infrared spectroscopy. The temperature dependences of infrared dichroismus were examined for the 900 cm -' (C ,-H bending vibration) and 600 cm ~ (acetyl group frequency) bands. The former changed at about 3 0 T , whereas the latter did not show any remarkable change. These results suggest that the transition observed here is probably related to the conformational change of the pyranose ring. The transition mechanism is supposed to be associated with the chair (C I)-boat (B) transformation of the pyranose ring at the folding of the cellulose molecule.
ZUSAMMENFASSUNG:Es wurde ein Ubergang 2. Ordnung von Cellulosetriacetat bei ca. 30°C mit Hilfe der Polarisations-Infrarot-Spektroskopie untersucht. Die Temperaturabhangigkeiten des IR Dichroismus der Banden bei 900cm -(C ]-H Biegeschwingung) und 600 cm -I (Acetyl-Gruppenfrequenz) wurden untersucht. Die 900 cm -Bande zeigte einen Ubergang bei ca. 30°C, wahrend die 600 cm-' Bande keine bemerkenswerte Anderung zeigte.Diese Ergebnisse legen nahe, daR der hier beobachtete Ubergang wahrscheinlich einem
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