BMIs, thermosetting

Other backbone structures that have generated interest are the polyether ketones. An attempt was made to synthesize amino-terminated arylene ether ketones, which were subsequently converted into the corresponding maleimide-terminated oligomers (37). The aim of this approach was to obtain tough, solvent resistant, high temperature BMI thermosets. 

A high-Tg hot/ wet resistant resin A toughened high-Tg BMI formulation A tough BMI system A BMI thermoset with thermoplatic-like toughness... 

A dicyanate ester. Due to their high cost, cyanate esters are not used as widely as epoxies but are now being used as blend candidates for improving the properties of epoxy and BMI thermoset resins in composites. 

V391 A BMI thermoset with thermoplatic-like toughness California... 

BMI intermediate synthesis [COMPOSITE MATERIALS - POLYTffiR-MATRLO - THERMOSETS] (Vol 7) -coumarin reduction [COUMARIN] (Vol 7)... 

A number of BMI resias based on this chemistry became commercially available through Rhc ne Poulenc for appHcation ia priated circuit boards and mol ding compounds and Rhc ne Poulenc recognized the potential of bismaleimides as building blocks for temperature-resistant thermoset systems. The basic chemistry, however, was not new, because the Michael addition reaction had been employed by Du Pont to obtain elastomeric reaction products from bismaleimides and Hquid polymeric organic diamines (15). 

In the narrow sense, bis-maleimide resin means the thermosetting resin eom-posed of the bis-maleimide of methylene dianiline (BMI, bis(4-maleimidophenyl)-methane) and methylene dianiline (MDA, bis(4-aminophenyl)methane) (Fig. 1). Beeause of the addition meehanism, the resin is eured without elimination, whieh is a eharacteristic of this resin. Bis-maleimide resin is used as a thermally stable matrix up to 204°C (400 F) whieh typical epoxy resins may not normally be used. However, in spite of having an imide structure, bis-maleimides are classified as being moderately thermally stable resins. The aliphatic structure of the resin is not stable for long periods above 232°C (450°F.) If a highly aromatic thermally stable thermosetting resin is necessary, acetylene end-capped aromatic imide-based oligomers should be used. 

Bis-maleimide resins composed of BMI and diamines have been reported in the early 1960s in the patent literature. Since that time, a number of patents have appeared describing improvements in their properties and uses [3]. Although many bis-maleimide resins are commercially developed, relatively few reports of their use as adhesives are to be found in scientific journals [4-10]. Improvements of maleimide resins are mirrored in the improvements of thermosetting polyimides. For example, the method of in situ polymerization of monomer reactants (PMR method) was developed [6]. 

Several researchers have modeled the cure kinetics of thermosetting resins in the past, including an unsaturated polyester resin [8], epoxies [9-11], and bismaleimide [5], As an example, a graphite/BMI material, IM6/3100, was modeled in [5] using... 

BMI/amine Michael adduct resins may be further modified and blended with other thermosets or reactive diluents to achieve either specific end-use properties or processability. Epoxy resins are very suitable for the modification of BMI/primary amine adducts, because the secondary amine functionality in the aspartimide structure is a curative for the epoxy group. 

The Diels-Alder reaction can be employed to obtain thermosetting polyimides. If BMI (the bisdienophile) and the bisdiene react nonstoichiometrically, with bismaleimide in excess, a prepolymer carrying maleimide terminations is formed as an intermediate, which can be crosslinked to yield a high temperature resistant network. 

BMI mtermediatesynthesis [COMPOSITE MATERIALS - POLYMER-MATRIX - THERMOSETS] (Yol 7) 4,4y-Dichlorodiphenyl-trichloroethane [50-29-3]... 

In the field of high thermomechanical performance polymers, linear and thermosetting systems offer complementary properties. Among the thermosetting materials, BMIs and BNIs have been extensively studied and are now commercially available. In this chapter, firstly the main preparation and characterization methods are reviewed, and then the chemistry of the polymerization processes is discussed for both families. For the BMIs, due to the electrophilic character of their double bond, different polymerization pathways have been published, which is not the case for BNIs. Special attention has been paid to thermal polymerization which has already been used in industrial achievements however, on the other hand, the structure of these materials has been considered for the purpose of establishing relationships between processability, stability and thermomechanical properties. 

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