Measurements of Tlρ as a function of temperature have been made on two polyethylene oxides (PEO) with molecular masses of 5,000 and 30,000. The T1ρ measurements show biexponential behavior of the relaxation function in the temperature range from 170 K to 350 K. The intensities of the components of the relaxation function are constant over this temperature range in agreement with the crystallinities of the samples. The two relaxation times can be associated with the crystalline and amorphous component; the relaxation time minima describe the α relaxation in the crystalline regions of PEO and the glass transition in amorphous PEO.
Die selektive Messung der Spin‐Gitter‐Relaxationszeit im rotierenden Koordinatensystem T1Q(13C) erzielt vergleichbare Ergebnisse zu Messungen mit MAS. Der Informationsgewinn gegenüber Protonenrelaxationszeitmessungen ist erheblich. Die effektive α‐Methyl‐Rotation zeigt die Kooperativität aller molekularen Bewegungsprozesse.
Mixing Functions of the Binary System N‐Methylcaprolactam – n‐Tetradecane
The liquid‐liquid equilibria(LLE) and the vapour‐liquid equilibria(VLE) at 60°C were measured in the binary system N‐methylcaprolactam (1) – n‐tetradecane (2). The enthalpy of mixing HE of the same system was extrapolated from HE – measurements of N‐methylcaprolactam with other alkanes. The limiting activity coefficients f∞1 and f∞2 were obtained by extrapolation from values of resp. in other alkanes. For a comparison the vapour pressures of the mixture were calculated by model equations with constants from the two limiting activity coefficients and with temperature dependent constants extracted from the LLE and HE measurements.
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