由對苯二甲酸(TPA)與乙二醇(EG)/新戊二醇(NPG)/1,4-丁二醇(BG)
/1,6-己二醇(HG)所產製的共聚酯,以核磁共振(NMR)測試共聚酯中 DIACID
及不同DIOL的含量,NMR的結果顯示,各種DIOL的沸點不同,沸點低的DIOL易
汽化不易反應,反應物與產物中各種DIOL及DIACID的莫耳數比例並不相同,
發現三氟醋酸(NMR測試時所用的溶劑),對共聚酯中直鏈的DIOL(EG/BG/HG)
較容易溶解,而對共聚酯中含有支鏈的DIOL (NPG)較不易溶解,所以僅含有
直鏈DIOL的共聚酯多出的DIOL或DIACID比較少,這些多出的DIOL或DIACID
是由於被溶劑溶解共聚酯的末端基所造成。共聚酯的玻璃轉移點(Tg)隨共
聚酯中DIOL的相對含量而變化,共聚酯中主鏈上含有的亞甲基(CH2)數目愈
少的DIOL愈多時,共聚酯的玻璃轉移點愈高,共聚酯中主鏈上含有亞甲基數
目多的DIOL較多時,共聚酯的玻璃轉移點愈低。共聚酯熔點(Tm)是隨共聚
酯中分子間的堆積而變化,共聚酯中若只含有直鏈的DIOL(EG/BG/HG)共聚
酯分子間容易堆積,可測得熔點,共聚酯中若含有支鏈的DIOL(NPG),共聚酯
分子間不容易堆積,形成非晶型共聚酯 (Amorphous copolyester),而測不
到熔點。紅外光譜(IR)吸收度的結果,共聚酯中各種DIOL主鏈上的碳鏈數
相差較大時(相差一個碳鏈以上),測量IR光譜與計算IR光譜結果較相近,共
聚酯中各種DIOL主鏈上的碳數相差較小時(僅相差一個碳鏈)測量IR光譜與
計算IR光譜結果差異較大。熱重量分析(TGA)測量結果顯示,共聚酯的剛硬
段(苯環)較接近者(含有 EG的共聚酯),熱裂解的溫度範圍較大,含有NPG的
共聚酯因為DIOL含有二個CH3的支鏈,提供電子的來源,促進熱裂解產物的
生成,使得共聚酯較易產生分解,熱裂解溫度範圍較小,共聚酯分子間堆積
良好者(含有 BG或HG的共聚酯),熱裂解溫度範圍則介於二者之間。

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.
In this research,copolyesters composed of terephthalic acid