| Summary: | 碩士 === 國立師範大學 === 化學學系 === 81 === In this research,copolyesters composed of terephthalic acid
(TPA)/Ethylene glycol(EG)/Neopentyl glycol(NPG)/1,4-Butane diol(
BG)/1,6-Hexane diol(HG) were synthesized.By the measure- ment
of Nuclear Magnectic Resonance (NMR),the ratios of dif- ferent
Diols and Diacid in the copolyesters were determined. The
composition of reactants and products is diffrernt. We found
that copolyesters containing linear diols(EG/BG/HG) dissolve
more easily in trifloroacetic acid than those copoly- esters
containing branch diol(NPG). However those copolyesters
containing linear diols consequently have more diol or diacid
in the contents,due to the end group effect of copolyesters.
The change of glass transition temperature(Tg) of copolyesters
depends on the relative contents of different diols. Copoly-
yesters containing fewer methylene groups have the higher Tg.
The melting temperature (Tm) of copolyesters depends largely on
the condition of intermolcular packing. Those copolyesters
containing linear diols(EG/BG/HG) have the advantage of easy
packing,these kinds of copolyesters have a clear Tm. The branch
diol (NPG) in the copolyesters results in the forming of
Amorphous copolyesters, so as a result we cannot measure the
Tm. The measurement of Infra Red (IR) absorbance show that
copolyesters contain two different diol,the diols' methylene
group number differences are not less than 2, the results of IR
absorbance of measurement and calculation are similar. The
results of thermal gravity analysis (TGA) show that
copolyesters thermal decomposition temperature depends largely
on their structures. Those copolyesters having rigider
structure posses a wider range of thermal decomposition
temperature than those of flexibler structure.
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