Study On Synthesis And Properties Of Aromatic Polyamide Containing Multi-ketonic Linkage And PMDA/TDPA Copolyimide

The polyamide and polyimide are high performance polymers with excellentthermal oxidation stability, mechanical properties, radiation resistance, and otherproperties, has been widely used in aerospace, military equipment, themicroelectronics industry, precision machinery manufacturing and other high-techfields. However, polyamide and polyimide has poor solubility and high cost, difficultto process, manufacturing, so its application is limited. So remain polyamide andpolyimide outstanding performance at the same time, improve the processingperformance has always been a hot topic in the research field of polyamide andpolyimide.This paper intends to analyze the relationship between structure and properties ofpolymer,2kinds of novel structure with dual-keto structure monomer1,3-di(4-chloroformyl benzoyl) benzene(IKC) and4,4′-terephthaloyl diphthalic anhydride(TDPA)were designed and synthesized.2kinds of polyamide cantaining multi-keto weresynthesized via low temperature solution polymerization by using IKC respectivelywith4,4′-diaminodiphenyl ether (ODA) and4,4′-diaminodiphenyl methane (MDA).Using TDPA as the third monomer, and pyromellitic dianhydride (PMDA) and4,4′-diaminodiphenyl ether(ODA) copolymer prepared series PMDA/TDPAcopolyimides. And the structure and properties of3kinds of polymers werecharacterized. The main research contents are as follows:(1)1,3-di(4-methyl benzoyl)benzene(Ⅰ) was prepared by Friedel-Craftsacylation reaction with toluene, isophthaloyl chloride (IPC) as the starting material,the yield is91.2%. Ⅰwith KMnO4/pyridine/H2O catalytic oxidation of1,3-di(4-carboxy benzoyl)benzene(Ⅱ), the yield rate is94.0%. Then the new structureof the monomer1,3-di(4-chloro formyl benzoyl) benzene(IKC) was prepared after Ⅱacylated with thionyl chloride at reflux, the yield was92.0%. And FT-IR,1H-NMRwere performed to characterize, results show that: IKC has the expected structure.(2) Through N2conditions,2kinds of polyamide cantaining multi-keto weresynthesized via low temperature solution polymerization by using IKC respectivelywith4,4′-diaminodiphenyl ether (ODA) and4,4′-diaminodiphenyl methane (MDA). The structure and properties of polymers were characterized by methods of FT-IR,TGA, DSC and WAXD method, the results show that: the polymer is soluble inconcentrated sulfuric acid, DMAc, DMF, NMP, have good solubility. Tg at about216℃～220℃,5%thermal decomposition temperature（Td5%） were405℃and420℃, the polymer has good thermal and oxidation stability.(3)1,4-di(3′,4′-dimethyl benzoyl)benzene(ⅰ) was prepared via Friedel-Craftsacylation reaction by o-xylene, terephthaloyl chloride(TPC) as the starting material,the yield is95.2%. ⅰby KMnO4/pyridine/H2O catalytic oxidation obtained1,4-di(3′,4′-carboxy benzoyl) benzene(ⅱ), the yield rate is94.3%. Then ⅱafteracylated with thionyl chloride at reflux, obtained polymerization level targetproduct(TDPA), the yield was93.5%. FT-IR,1H-NMR were used to characterizeTDPA, results show that: TDPAhas the expected structure.(4) Using4,4′-terephthaloyl diphthalic anhydride(TDPA) as the third monomer,and pyromellitic dianhydride(PMDA) and4,4′-diaminodiphenyl ether(ODA)copolymer prepared polyamide acid solution(PAA), acuum filtration deaeration,Casting film in clean glass plate, stripping agent after thermal imidization preparedseries of PMDA/TDPA copolyimide films, the structure and properties of films werecharacterized by methods of FT-IR, TGA, DSC, mechanic performance text. Theresults show that: polymide,s glass transition temperature decreased with theintroduction of double-ketonic linkage, solvent stretch film processing performanceimproved significantly, film’s Td5%at higher than515℃, the tensile strength is above111MPa, films have excellent thermal stability and mechanical properties, have broadapplication prospects.