Bismaleimide polymer

BISMALEIMIDE POLYMERS. These relatively new polymeric materials were developed to serve the increasing requirements for materials of high strength in high-temperature applications. Currently, a high percentage of the bismaleimides produced are used for printed circuit boards (PCBs). The materials usually are cured with aromatic amines and then compression molded into the PCBs. Future uses include aircraft structural components where bismaleimides may prove superior for high-temperature skin surface applications as compared with present epoxy composites. 

From the same nitrone, or glyoxal-bis(>V-phenyl)-nitrone and m- or p-phenylene-bismaleimide, polymers, 88-91 are obtained.94 Some physical properties of these polymers are summarized in Table VII. 

Polymers based on AB2 types have been reported to be used in combination with bismaleimide polymers, in order to initiate curing. Monomers for hyperbranched poly(arylamide)s are shown in Figure 13.4. 

When monomers of the AB2 types are used, hyperbranched polymers will be formed on polymerization. The polymers can be employed to initiate bismaleimide polymerization. Another application of these polymers is to increase the toughness for thermosets such as bismaleimide polymers and epoxies. 

Takeichi Tsutomu, Saito Yuki, Agag Tarek, Muto Hiroyuki, and Kawauchi Takehiro. High-performance polymer alloys of polybenzoxazine and bismaleimide. Polymer. 49 no. 5... 

Tian Xiao-Wei, and Yang Zhen-Guo. Effect of CTBN concentration on thermal and morphological properties of binary copolymers of o-cresol novolac epoxy resin and bismaleimide. Polym. Plast. Technol. Eng. 50 no. 5 (2011) 474-480. 

Coagents ate often used with peroxides to increase the state of cure. Some coagents, such as polybutadiene or multifimctional methacrylates, are used at high levels to form polymer grafts or interpenetrating networks. Other coagents such as triaHyl cyanurate, triaHyl trimelHtate, and y /i -phenjiene bismaleimide are used at low levels to reduce the tendency of the polymer to degrade by chain scission. 

Currendy, epoxy resins (qv) constitute over 90% of the matrix resin material used in advanced composites. The total usage of advanced composites is expected to grow to around 45,500 t by the year 2000, with the total resin usage around 18,000 t in 2000. Epoxy resins are expected to stiH constitute about 80% of the total matrix-resin-systems market in 2000. The largest share of the remaining market will be divided between bismaleimides and polyimide systems (12 to 15%) and what are classified as other polymers, including thermoplastics and thermoset resins other than epoxies, bismaleimides, cyanate esters, and polyimide systems (see Composites,polymer-matrix-thermoplastics). 

Micha.elAdditions. The reaction of a bismaleimide with a functional nucleophile (diamine, bisthiol, etc) via the Michael addition reaction converts a BMI building block into a polymer. The non stoichiometric reaction of an aromatic diamine with a bismaleimide was used by Rhc )ne Poulenc to synthesize polyaminobismaleimides as shown in Figure 6 (31). 

The Michael addition of nucleophiles to the carbon—carbon double bond of maleimide has been exploited ia the synthesis of a variety of linear polymers through reaction of bismaleimide with bisthiols (39). This method has been used to synthesize ethynyl-terminated imidothioether from the reaction of 4,4 -dimercaptodiphenyl ether [17527-79-6] and A/-(3-ethynylphenyl)maleimide (40). The chemical stmcture of this Michael addition imide thermoset is as follows ... 

A variety of bifunctional compounds react with the bismaleimides to form polymers by rearrangement reactions. These include amines, sulphides and aldoximes (Figure 18.41). 

If the bismaleimide-amine reaction is carried out with a deficiency of amine the polymer will have terminal double bonds which allows a cure site to give a thermosetting polymer via a double bond polymerisation mechanism. This approach was developed by Ciba-Geigy with their product P13N (Figure 18.42). 

Interfacial adhesion and, thereby, compatibility can be enhanced by the selective crosslinking reaction in polymer blends. Inoue and Suzuki [26] reported the properties of blends dynamically crosslinked PP-EPDM blends. The crosslinking agent was yV,N -/w-phenylene-bismaleimide - poly(2,2,4 - trimethyl - 1,2-dihydroquino -line) system. Increase in interfacial adhesion leads to... 

Stenzenberger H. D. Thermosetting Polyimides from Bismaleimides via Diels-Alder Reaction in Polyimides Other High-Temp. Polym., Proc. Eur. Tech. Symp., 2nd" 1991 215, Eds. Abadie M. J. M. and Sillion B., Pb. Elsevier Amsterdam... 

K Dusek, L Matejka, P Spacek, H Winter. Network formation in the free-radical copolymerization of a bismaleimide and styrene. Polymer 37 2233-2242, 1996. 

An alternative scheme for incorporating chemically reactive anthracene monomers made use of anthracene mono-carboxylic acid, therefore resulting in chain capping of the PET chains with anthracene units. Reaction (either in solution or via reactive extrusion) with bismaleimides resulted in chain extension, increasing polymer molecular weights from 6000-10000 to 20000-25 000 in as little as 3 min reaction time (Figure 6.8) [71, 72], While such an approach could hold great promise for the rapid manufacture of polyesters, it should be pointed out that these chain-extended materials all were amorphous materials. 

Bismaleimide (BMI) polymers are produced by reaction of a diamine and a bismaleimide (Eq. 2-211) [de Abajo, 1988, 1999 Mison and Sillion, 1999]. Polymerization is carried out with the bismaleimide in excess to produce maleimide end-capped telechelic oligomers (XLVI). Heating at temperatures of 180°C and higher results in crosslinking via radical chain... 

BMI polymers have glass transition temperatures in excess of 260°C and continuous-use temperatures of 200-230°C. BMI polymers lend themselves to processing by the same techniques used for epoxy polymers. They are finding applications in high-performance structural composites and adhesives (e.g., for aircraft, aerospace, and defense applications) used at tem-peratrues beyond the 150-180°C range for the epoxies. Bisnadimide (BNI) polymers are similar materials based on bisnadimides instead of bismaleimides. 

Bisbenzocyclobutenes readily react with molecules which contain sites of reactive unsaturation such as bismaleimides [10,13, 31, 32]. This is in essence, a novel type of Diels-Alder polymerization in which the bis-diene is latently embodied within two benzocyclobutene moieties. The properties of these polymers depends strongly on the mole ratio of the monomers and when it is equimolar, can result in some exceptionally tough high Tg resins [33, 34]. 

Diels-Alder mechanism. It was found that those polymers which had the least weight loss in the isothermal aging study were derived from those monomers which by DSC polymerized to the greatest extent by a Diels-Alder mechanism. It was inferred therefore that if similar considerations apply to the copolymers of bismaleimides and bisbenzocyclobutenes then these materials too might be the result of predominantly Diels-Alder type polymerizations. To the extent to which these conclusions are correct, the enhanced thermal stability of the bisbenzocyclobutene/bismaleimide copolymers is likely to be due to their being Diels-Alder polymers of some sort. 

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