New High Pressure Polymerization and Simultaneous Processing for Polyaminoimide from Aromatic Diamine and Bismaleimide

Abstract

ABSTRACT:The simultaneous polymerization and processing under high pressure was carried out by using a piston-cylinder type hot pressing apparatus. Before the polymer synthesis, the Michael addition of aniline to N-phenylmaleimide was performed under high pressure as a model reaction, giving N,N'-diphenylaspartimide. The Michael-type polyaddition of 4,4'-methylenedianiline to 4,4'-bismaleimidodiphenylmethane under 150-820MPa at 180-300°C for 20-40h afforded the linear polyaminoimide having inherent viscosities in the range of 0.2-0.8dlg-1 . When the polymerization was carried out at higher temperature, the closslinked polymer was produced. The polymerization under higher pressure required higher temperature. The closslinked polymer synthesized under high pressure was very hard resin with Vickers hardness of 330-360 MPa and high modulus ( > 1.5 GPa), compared with the polymer obtained under ordinary pressure.KEY WORDS High Pressure Polymerization / Polyaminoimide / MichaelType Polyaddition / Bismaleimide / Polyaminoimide resins derived from aromatic bismaleimides and aromatic diamines are known as a class of high temperature thermosetting addition-type polyimides, and used widely as matrices for composite in electronics and aerospace industries. 1 -3 The advantage is that they contain reactive maleimide groups, which are thermally polymerizable without the elimination of volatile by-products that cause voids in highly closslinked polymeric materials.In the field of synthetic polymer chemistry, the reactive hot pressing technique has been developed for many years. 4 • 5 The concept of this technique is to simultaneously synthesize and mold intractable polymeric materials directly from solid monomers, and the technique was applied to the polymerizationprocessing of high temperature aromatic polymers. The application of high pressure to Michael addition reactions has been demonstrated to be extremely effective means due to both kinetic and thermodynamic backgrounds. 6 • 7 We already reported the application of high pressure to the cycloaddition polymerization of p-cyanobenzonitrile N-oxide and found that the solid state polymerization at room temperature giving poly-1,2,4-oxaziazole was accelerated under high pressure. 8 The present investigation was undertaken to explore high pressure polymerization and simultaneous processing for the polyaminoimide by the Michael-type polyaddition of 4,4' -bismaleimidodiphenylmethane (BMI) to 4,4'-methylenedianiline (MDI) without use of both solvent and catalyst [eq l].

Synthesis and Characterization of Some Bismaleimides Containing Ether Groups in the Backbone

“…The thermal stability of the polymers was evaluated by comparing the initial decomposition temperature (IDT) and percent char yield at 600 8C; the values are presented in Table 1. Figure 3 represents the thermogravimetric traces of crosslinked polymers obtained from the bismaleimides (1)(2)(3)(4)(5) in air.…”

“…They can be used as matrix resins for advanced composites. [1][2][3][4][5] These monomers cure through addition reactions to give highly crosslinked network polyimides having good physical and mechanical properties. Bismaleimides do have problems with high curing temperatures, brittleness and a high T g of the final polymer due to the high crosslinking density in the polymer network.…”

A New Facile and Rapid Synthesis of Polyamides and Polyimides by Microwave-Assisted Polycondensation

“…2,5-di(ethoxycarbonyl)terephthalic acid (PME), was synthsized according to the reported procedure (21) by the reaction of PMDA with absolute ethanol. A series of nylon-salt-type monomers XPMA and XPME, where X stands for the number of methylene unit in the aliphatic diamine, were prepared by a usual procedure by mixing an ethanol solution of an aliphatic diamine with an ethanol solution of PMA and PME, respectively, followed by recrystallization of the resultant precipitates with water (22,23).…”

Synthesis and thermal behavior of some brominated bismaleimides and polyaspartimides

“…All resulting polymers were redissolved in fresh solvent, precipitated in a nonsolvent medium, and dried for 16 h in a vacuum oven at 80 C. 22 The synthetic pathway to prepare these polymers is illustrated in Scheme 2.…”