Preparation And Properties Of Novel Solube Polyimide

Polyimide is one of the important polymer materials,but the traditional polyimide is difficult to dissolve and melt due to the regular molecular chain arrangement and strong intermolecular interaction,which restricts its application and development to a certain extent.And because soluble polyimide its special structure,not only retained the traditional polyimide good chemical stability,heat resistance,mechanical properties,electrical properties,optical properties,etc,also can well dissolve in organic reagent,easier to process molding is applied to aerospace,military weapons,electronic appliances,environmental protection material,separation membranes,and many other fields,It has become one of the indispensable polymer materials in the process of industrialization in China.In this paper,four diamine monomers,m-Phenylenediamine,m-Xylylenediamine,BAPP and sebacediamine,were used to make them mixed with trimental anhydride by 1: 2.The corresponding four imine diacids were formed by the mole ratio reaction of 2,which were successively denoted as m-Phenylenediamine diacid(PTDA),mXylylenediamine diacid(MTDA),BAPP imine diacid(BATDA)and sebacine diamine diacid(DTDA).The four diacid monomers were characterized.Then the four imide diacids were polymerized with diethylene glycol and ethylene glycol at the molar ratio of 1:1,and finally eight soluble polyimide resins and films were obtained,which were successively named as PPTD,PPTE,PMTD,PMTE,PBTD,PBTE,PDTD and PDTE type.The structure of the functional groups was determined by infrared spectroscopy,and the solution viscosity,thermal properties of the resin,optical,mechanical,dielectric,surface properties and hydrophobic properties of each new soluble polyimide were studied.Finally,the following conclusions are drawn:First of all,the four imine diacid monomers required for the synthesis of polymers have high chemical stability and heat resistance.The temperature of TGA at TD10% is maintained at about 400?,and the melting point of DSC is above 200?,and the trough of melting point spectrum is sharp,indicating that the synthesized monomers have high purity and meet the requirements of polymerization.For the 8 kinds of polyimides,PPTD and PPTE polyimides have good mechanical and optical properties,but poor dielectric properties and other properties.PMTD type and PMTE type introduced methyl structure,which increased the molecular volume and molecular weight of polyimide resin.Compared with PPTD and PPTE,the solution viscosity increased slightly,the dielectric constant decreased,the dielectric loss decreased,but the change was not significant,and the heat resistance was weakened,indicating that the introduction of methylene group had little effect on the dielectric properties of polyimide molecules,while enhancing the flexibility of resin molecules,so the heat resistance was decreased.PBTD and PBTE polyimides have the highest viscosity,the strongest mechanical properties,dielectric properties,optical properties,thermal properties and good surface properties and water absorption due to the high proportion of benzene ring and the highest molecular weight.However,PDTD and PDTE resins have the lowest relative molecular weight,the worst mechanical properties,good optical and dielectric properties and other properties due to the large proportion of C-C single bond in the molecule.In general,PBTD polyimide has the best comprehensive properties,with elongation at break of 5.8%,tensile strength at break of 54.1MPa,maximum visible light transmittance of 88.53%,TGA thermal decomposition temperature above 500?,and viscosity of solution system at 30? of 1770 m Pa.s.The dielectric constant is2.31,dielectric loss is 0.35%,and it has good surface properties and water absorption.