Authors:W. Miyano, E. Inoue, M. Tsuchiya, K. Ishimaru, and T. Kojima
DSC studies are given for polytetrahydrofurans with molecular masses equal to 650, 1400, and 2900, for their blends, and for
their cured samples. The samples were stored, annealed, and quenched to obtain the samples with different thermal histories.
Two or more endothermic peaks appear in the DSC curves for the stored samples, even for the non-blended samples. A hyperbolic
curve forced the plot of the highest melting temperature vs. the molecular mass to asymptote to about 50C. The relationship
between the highest melting temperature and the composition for the blended samples is suitable to linear or Fox’s relation.
A peak and a shoulder appear in the DSC curves of the cured samples. As the samples are cooled at the faster rates in the
thermal treatment, the shoulder appears at the lower temperatures.
Summary A double endothermic peak appears in the DSC curve of a PTHF oligomer. In order to investigate this phenomenon, a two-component blend of PTHF was prepared with a number average molecular mass of M=1400, and the double endothermic phenomena were investigated by TM-DSC. The larger the amount of the long chain component in the PTHF blend, the smaller the difference between the Cp-T curve and the normal DSC curve. The amounts of endothermic energy ?Hendo,1, ?Hendo,2 and exothermic energy ?Hexo,1, ?Hexo,2 in each peak at infinite modulation frequency were estimated.
Authors:E. Inoue, M. Tsuchiya, K. Ishimaru, and T. Kojima
TG studies are given for PMMA prepared by radical polymerization, PTHF prepared by cationic polymerization, and their blends.
A procedure is proposed for determining the activation energy, frequency factor, and the order of events corresponding to
the respective stages of the multistage TG curves. The order of the initial event of PMMA is not the 1st. It is shown for
this discussion that the relationship between mass loss and time of the 2nd order reaction is similar to that of the depolymerization
including the vaporization process at the earlier times. Some of TG curves of PTHF are not dependent on the heating rate.
This independence depends on the size of sample. The order of event of PTHF, which is obtained from TG curves dependent on
the heating rate, is the 0th. The event order equal to the 0th reflects major contribution of vaporization in the event. The
TG behaviors shown by the procedure mentioned above for the PMMA/PTHF blends with the smaller PMMA or PTHF contents cancel
those of PMMA or PTHF.
Melting behaviours of poly(oxytetramethylene)glycols (POTMGs) with different molar masses were investigated by temperature-modulated
differential scanning calorimetry (TMDSC) and relaxation times within the melting range were estimated from the modulation-frequency
dependence of phase angle δ. An Arrhenius plot of the relaxation times exhibited a plateau in the lower melting peak region
of POTMGs with molar masses of 1400, 1000 and 650. This plot was compared with the standard DSC curve. The apparent activation
energy was estimated from the relaxation time in the upper and lower sides of a melting temperature region: slight dependence
on the molar mass was observed for the former region whereas the maximum value was obtained for a molar mass 1400 for the
Authors:D. Filip, C. Simionescu, D. Macocinschi, and I. Paraschiv
Miscibility in blends of semicrystalline polymers (poly(ethylene) adipate and poly(tetrahydrofuran)) and liquid crystal cholesteryl
palmitate was investigated by means of differential scanning calorimetry and polarizing optical microscopy. Some(concentration-dependent)
miscibility was found. A more pronounced miscibility exhibits the polyester-based blends probably due to the similar chemical
structure of the two components and stronger interactions between the two components.
Authors:H. P. de Oliveira, J. Rieumont, C. Nogueiras, D. Souza, and R. Sánchez
) shows many features in common with its homologues poly(trimethylene oxide) and poly(tetrahydrofuran), with the main degradation processes being accounted by homolysis of the C–O backbone [ 25 , 26 ]. The weakest bond in the backbone, and, therefore, the