Curing reactions and modeling of silicone-carbon resins

✍ Scribed by Leo J. Kasehagen; H. N. Cheng; Patrick J. Cowan

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 303 KB
• Volume: 64
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/(sici)1097-4628(19970523)64:8<1557::aid-app13>3.0.co;2-v

✦ Synopsis

New silicone-carbon resins have been made, based on four-or five-membered cyclosiloxanes, cyclopentadiene dimer (DCPD), and cyclopentadiene trimer (TCPD). The monomers are first polymerized to a B-stage resin, and then heated at higher temperatures to cure. In this work, the curing reaction of this silicone-carbon resin (which leads to network formation) is simulated using two approaches. In the first approach (stochastic model), all the available functional groups (olefin and silyl hydride) are allowed to react with each other with equal probability. This gives the kinetically controlled, liquidlike, diffusion-free limit. Extrapolation of the model to reactions where diffusion may play a role can be made by including molecular weight dependence in the rates. This dependence on the molecular weight can be scaled to fit the experimental data. In the second approach a percolation model is used. In the extreme case, this model corresponds to the solid-state reaction between silicone-carbon resin molecules on 2-dimensional or 3-dimensional rigid lattices. Relaxation of this geometric constraint can be made by providing a larger reacting distance between the reactants. Computer programs have been written for 2-and 3-dimensional lattices. Illustrative examples are given for these approaches.