(1) Aerospace and high-end technology. NASA (USA NASA) for manufacturing high speed aircraft, looking for the structure of resin, the thermoplastic polyimide and is connected to a different group of imide synthetic polymer were studied. In the reactive group several possible, phenylethynyl groups were selected. Because of this kind of compounds provides the overall best performance, it has the long period of storage at room temperature, curing the polymer excellent characteristics. 80's last century AKRON University began to study the working end phenylethynyl imide oligomer, several Related Companies such as National StarchandChemicalCompany, in the hope that this technology. Japan and American are developing new century of supersonic aircraft (HSCT), the plane carrying 300 passengers, flight speed more than 2 times the speed of sound, the service life of 60000 hours (about 6.8 years), the weight of nearly 400 tons. But due to the increase of body temperature increases with the aircraft speed, the surface temperature of about 200 ℃ -50 ℃; at the same time, to cross the take-off and landing in the atmosphere, the flight 1 times must be -50 ℃ and 200 ℃ temperature two times. The carbon fiber reinforced epoxy composites have not used, so the maleimide (BMI) additive PI and thermoplastic PI emerge as the times require. Low thermal expansion PI addresses the composite thermal stress problem, its superiority is more important.Such as: ① as a semiconductor film, and the inorganic membrane stamping moisture. Low thermal expansion PI coating material as a protective film of semiconductor element, can overcome the inorganic membrane bubble, crack occurrence rate. As a non thermal stress storage elements with alpha ray shielding film. ③ for flexible printed circuit board, which is the most important use of PI thin films. Can foreknow, low thermal expansion PI with excellent comprehensive performance, will be widely applied to the microelectronic technology and aerospace fields.
(2) The microelectronics industry. PI as a new material for electronic components connection and protection. In recent years, in order to satisfy the signal transmission speed, improve the function requirements of electronic circuit, PI has a lower dielectric constant. The dielectric constant of general Homo aromatic thermoplastic PI thin films was in the range of 3.0-3.5, requirement is reduced to below 2.5, Tg value should be higher than 400 ℃, the film thickness in the 0.5-10 M. In the study by PI nanofoam films, in addition to the use of poly propylene oxide is also used PMMA, PMS (poly methoxy styrene) as the thermal decomposition of polymers. Made of PI nano foam film (diameter 8nm, pore is 20%) dielectric constant is in 2.5 the following, to meet the basic requirements.In addition, PI nano foam film company with IBM PI and excellent thermal stability and decomposition of polymer block, graft copolymerization and become, its dielectric constant is less than 2.5, the film thickness is 0.5-10 μ m, foam porosity is about 20%, about 10nm in diameter, and can meet the need of the microelectronics industry. But there are nano pore collapse collapse (collapse) problem to be further solved
(3) Polyimide with low coefficient of thermal expansion. Composite materials are formed of polymeric materials to metal, ceramics and other inorganic materials more people's attention. But compared to inorganic materials, polymeric materials heat resistance is relatively poor, the coefficient of thermal expansion (CTE) of two large, complex, along with the change of the temperature, there will be thermal stress of the composite material cracking and other undesirable phenomena. Therefore different composite materials by thermal expansion coefficient difference caused by thermal stress is an important problem.As a leader in polyimide polymer materials, people want to use its excellent performance at the same time, can reduce the thermal expansion coefficient, make it better and the inorganic material composite with. Of polyamic acid (PA) polymer blending preparation PA mixed solution, and then cast film, drying imidization, got the CTE for PA solution cast film 210-6/K, flexibility is good, no cracking phenomenon.In addition, also can be used for low thermal expansion PI with more than two kinds of two amines and two anhydride copolymer, mechanical mixing copolymerization system, adding additives containing metal ions, such as adding 4%-30% additive containing metal ions of PI in addition to stick to glass, metal and other inorganic materials are greatly improved, but also because of Si-OH the existence of thin flexible.
(4) Polyimide foam. Polyimide foam materials according to the structure is divided into two categories: thermosetting polyimide foam (such as bismaleimide (8M1), PMR type polyimide) and thermoplastic polyimide foam. Polyimide foam materials by the NASALangley Research Center, developed in partnership with UnitikaAmerica, which has been widely used in aircraft, train, car, ship etc..Its advantages are: first, good heat insulation and sound insulation effect; the flame retardant, anti fire, no smoke, no harmful gas; the foam density according to the requirements of the high, low temperature; change; the good flexibility and elasticity. The nanometer effect of nano polyimide foam materials and their physical and chemical properties of special is the focus of current research. At high fields such as oil drilling, aviation and aerospace fields such as reconnaissance satellite, missile weapon equipment such as high temperature resistant parts, polyimide foam materials will be widely used.
Polyimide advantage has been limited in temperature resistance, radiation resistance, its mechanical performance is still far from achieving the desired level of polyimide structure. The main reason is the polymer solubility synthetic technology past immaturity, imide method difference, and spinning technology has great difficulty. High strength, high modulus, high temperature resistant, radiation resistant polyimide fiber is caused extensive attention all over the world, and it will attract more researchers to participate in research and development, which will bring a new leap forward to the research and development of polyimide fiber.
With the development of aerospace, automobile, especially for the development of the electronics industry, an urgent requirement for electronic equipment miniaturization, lightweight, high function. Excellent polyimide was on display one's skill to the full, its growth rate has been maintained at around 10%. At present, the development trend is to introduce the two benzene amine structure or other special engineering plastic alloy, in order to further improve its heat resistance, or with the PC, PA and other engineering plastics alloy to improve its mechanical strength.