乙烯基對苯二甲酸-共-對羧基苯甲酯熱向型共聚酯的研究

Abstract

將聚(乙烯基對苯二甲酸)(Polyethylene Terephthalate)(簡稱PET)與對 羧基苯甲酸(p-acetoxybenzoic acid)(簡稱PAB)進行聚縮合反應 polycobdensation),得到一系列不同組成POB/PET的熱向型共聚酯.以DSC( differential scanning calorimeter)討論組成和固態聚 反應的影響,以 PET polymer合成之共聚酯較以PET oligomer合成者鐃I高,在含POB組成較 高的情況下,因其結晶由均向性(isotropic)變鬥D均向性(anisotropic), 吸熱峰變得較小且熔融熵(enthalpy ofusion)變小.此種共聚酯在不同組 成下的結晶形態學則由偏光顯微鏡加以探討,i證實當POB組成高於60mole% 時非均向性非常明顯, 固態聚合使兩種捰邑i行酯交換而紊亂化( randomization),可由NMR光譜分析而得.熱刺激去極化(thermally stimulated current TSC)用來分析此@液晶共聚酯可獲得在玻璃轉移溫度 附近相變化和熱鬆弛的結果,並導X一模式,以研究共聚酯中的次序分布( sequence distribution)及團憳□degree of blockiness)等等,並可成功 地預測在不同組成和測量囓韝U的情況. A series of Co[Poly(Ethylene terephthalate-p-oxybenzoate) ]hermotropic copolester were synthesized from various ratiosf two different moieties of either poly(ethylene terephtha-ate) or its oligomer with p-acetoxybenzoic acid througholycondensation process. Effects of composition and solid state polymerization onSC(differential scanning calorimeter) are discussed. Theelting point of copolyester possess a higher value if theET polymer is used as PET moiety in the copolyesters. InSC scan of the POB-rich scan composition, the endothermiceak shows obscurely and enthalpy of fusion becomes smallue to the change in the crystalline morphology from isotro-ic to anisotropic. A detailed description of the crystalline morphology ofopolyesters with different compositions as well as underifferent preparation temperature is discussed by using aolarized optical micrograph. It is found that the copoly-ster with the POB composition content above 60mole% werehown to be highly anisotropic. The solid state polymeriza-ion may cause the randomization of two units due to a trans-sterification reaction that is examined by NMR spectroscopynalysis. Thermally stimulated current (TSC) method can be employedo evaluate the characterization of this type of liquidrystalline polymers. The transition/relaxation of liquidrystalline polymers around its glass transition temperatureas been investigated. And the sequence distribution, inerms of the degree of blockiness, in dual chemidomains ofOB/ PET copolyester is simulated from a model developed bys to predict the probility between block sequence and randomequence under a given composition and measuring condition.