Dicyclopentadiene reaction injection molding

Poly(dicyclopentadiene). The development of polydicyclopentadiene [25038-78-2] for reaction injection molding is an area which has generated much interest. The polyDCPD is obtained via metathesis polymerization of high purity (usually greater than 98%) DCPD. Excellent reviews (61—62) of the chemistry and properties of polyDCPD have been pubHshed. The patent Hterature of polyDCPD synthesis, catalysts, modifiers, and appHcations is dominated by Hercules (44 patents) and B. F. Goodrich (43 patents) in the U.S. Other participants are Orkem, SheU, Nippon Zeon, and Teijin. 

Tungsten-based catalysts with a Lewis base promoter are used in the polymerization of dicyclopentadiene also isolated from the C5 stream-cracker fraction.150,155 The product poly(dicyclopentadiene) or Metton resin has unusual physical and chemical properties. It is processed together with elastomers to increase viscosity of the end product by using reaction injection molding (RIM) technology.155... 

Dicyclopentadiene is also polymerized with tungsten-based catalysts. Because the polymerization reaction produces heavily cross-linked resins, the polymers are manufactured in a reaction injection molding (RIM) process, in which all catalyst components and resin modifiers are slurried in two batches of the monomer, The first batch contains the catalyst (a mixture of WClg and WOCl4), additives, and fillers the second batch contains the co-catalyst (a combination of an alkylaluminum compound and a Lewis base such as ether), antioxidants, and elastomeric fillers. Mixing two liquids in a mold results 111 a rapid polymerization reaction. 

The ring-opening metathesis polymerization of dicyclopentadiene was monitored by ultrasonic spectroscopy.16 The thermoset poly(dicyclopentadiene) is formed by ringopening and cross-linking in a reaction injection molding system. A reaction cell with a plastic window was constructed for use with pulse echo ultrasonic spectroscopy. Realtime measurements of density, longitudinal velocity, acoustic modulus and attenuation were monitored. Reaction kinetics were successfully determined and monitored using this technique. 

To date, low volumes of materials have been produced commercially from norbomene and cyclo-octene. Numerous products are expected to result from the materitd produced by the ROMP of dicyclopentadiene in a RIM (reaction injection molding) process. In a RIM process, two streams of a monomer are mixed in the mold where it is polymerized to the final part. In this case, one of the monomer streams contains a tungsten complex while the second contains an alkyl aluminum activator. When the two streams of dicyclopentadiene are mixed, the metathesis catalyst is formed and the monomer is ROMP polymerized (equation 12). 

Commercial synthesis of unusual polymers has also been possible with the Grubbs metathesis catalyst. Polydicyclopentadiene can be formed from dicyclopentadiene by ROMP. In the reaction, the strained C=C bond indicated by the arrow in 12.5 initially polymerizes the presence of the second C=C bond allows some cross-linking to occur, giving exceptional strength to the material, which can even stop bullets within a few centimeters Direct reaction injection molding has proved possible in which the monomer and catalyst are injected into the heated mold and the item formed in place. The polymer is being used to fabricate sports equipment and several other applications are being considered. 

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