| Summary: | 碩士 === 大同大學 === 化學工程研究所 === 88 === ABSTRACT OF PART I
In this research, it was discovered that two kinds of insoluble polyimides (PI) could form the soluble copolyimides (CoPI) through copolymerization. Among various kinds of PIs, the physical properties of the symmetrical biphenyl dianhydride (s-BPDA) Series were the best; however, their organic solubilities were inferior on the whole. PI (IIIB) synthesized from s-BPDA and 1,2-bis(4-aminophenoxy)benzene (CDA) deriving from catechol not only possessed excellent tensile characteristics, including the film’s yield point strength of 116 MPa, break strength of 100 MPa, initial modulus of 2.3 GPa, and break elongation percentage of 112%, but also had the feature of increasing the solubility of its CoPI. IIIB was only slightly soluble in solvents of NMP, etc (＜1 wt%); however, as CDA mixed in equal moles with several kinds of aromatic diamines, which originally formed insoluble s-BPDA-PI, e.g., 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)-2-t-butylbenzene, 3,4’-oxydianiline and 4,4’-bis(4-aminophenoxy)-3,3’,5,5’-tetramethyl biphenyl, etc, they would form CoPI (IVb, IVe, IVi, IVl) soluble in NMP (≒10 wt%), by copolymerizing with s-BPDA. In this work, CDA reacted with 11 kinds of aromatic diamines to form CoPI (IVb—l) and their physical properties were compared with those of PI of the corresponding s-BPDA Series (Va—l).
ABSTRACT OF PART II
Organosoluble s-BPDA-1,2-BAP-tBB Series copolyimides (CoPI-I; CoPI-II) have been derived from 1,2-bis(4-aminophenoxy)-4-t-butylbenzene (1,2-BAP-tBB) via the copolymerization method to improve the poor solubility of s-BPDA Series polyimide (PI). CoPI-Ia—m and CoPI-IIa—m were copolymerized from a pair of diamines including 1,2-BAP-tBB (In) and 13 kinds of aromatic diamines (Ia—m) that formed insoluble PI in molar ratios of 1：1 and 2：1 separately with s-BPDA. The copolymers showed improved solubility in organic solvents, especially in NMP, m-cresol, and pyridine. For Series CoPI-I, the polymers could readily soluble in NMP and m-cresol except the polymers CoPI-Ia and CoPI-Id which were only partially soluble in NMP; for Series CoPI-II, the polymers could readily soluble in those two solvents at room temperature.
The two series of CoPI exhibited excellent mechanical properties. All the CoPIs revealed obvious strength at yield (91—111 MPa) except CoPI-Id and CoPI-Ig, strength at break of 80—110 MPa, and initial modulus of 2.0—2.4 GPa. The elongation at break of Series CoPI-I could up to 95% and was higher than that of Series CoPI-II (up to 75%). The glass transition temperatures (Tgs) of most Series CoPI-I polymers (247—299℃) were a slight higher than those the Series CoPI-II polymers (253—272℃). The two series of CoPIs were similar in their thermal stability, and their 10% weight loss temperatures (T10s) in nitrogen were between 530—570℃ and their char yields at 800℃ ranged between 50—65%, indicating that those two series copolyimides have excellent high-temperature resistance.
ABSTRACT OF PART III
A new diimide dicarboxylic acid, 1,2-bis(4-trimellitimidophenoxy)-4-t-butylbenzene (I), was prepared by the condensation of 1,2-bis(4-aminophenoxy)-4-t-butylbenzene (1,2-BAP-tBB) and trimellitic anhydride (TMA) at 1:2 molar ratio. The diamine 1,2-BAP-tBB was first synthesized from 4-t-butylcatechol and p-chloronitrobenzene in the presence of potassium carbonate (K2CO3) and then reduced by H2NNH2 and Pd/C. A series of novel poly(amide-imide)s (PAIs) IIIa—k with inherent viscosities of 0.83—1.73 dL/g was prepared from the diimide-diacid I with various aromatic diamines (IIa—k) by direct polycondensation in a medium consisting of N-methyl-2-pyrrolidone (NMP) (as a solvent), triphenyl phosphite/pyridine (as condensing agents), and calcium chloride. Most of the polymers show excellent solubility in amide-type solvents such as NMP and N,N-dimethylacetamide (DMAc) and formed a tough, transparent, and flexible film by casting from DMAc solution. The films have tensile strengths of 87—108 MPa, elongations at break of 8—17%, and initial moduli of 2.1—2.6 GPa. The glass transition temperature of these polymers is in the range of 234—276℃ and the 10% weight loss temperature is above 475℃ in air or in nitrogen.
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