Utilization of Microgravity and High Gravity to Prepare Materials with Controlled Properties
The most promising way to extend the scope of properties of known materials is to increase the number of controlled external factors involved in the manufacturing process. These factors include gravitational and centrifugal forces. In particular, in polymer processing many advantages can be gained from changing the level of the mass forces. This conclusion relies on the fact that the density of the reaction mixture during polymerization varies due to heat liberation and to conversion of a monomer to a polymer. The more predictable gravitational effect is convection in a liquid monomer in the early stages of reaction. Convection stirs the reaction mixture, leading to a more uniform temperature and a more uniform degree of conversion. While participating in convective motion, the mixture continues polymerizing and may lose fluidity before homogenization is complete. The gradients of temperature and degree of conversion leads to a variation in the reaction rate and, as a result, to an inhomogeneous polymeric microstructure and a nonuniform distribution of properties in finished products.
KeywordsConvective Motion Mass Force High Gravity Heat Liberation Frontal Polymerization
Unable to display preview. Download preview PDF.
- 1.A. Sadykov, V. Leontyev, Y. Mangutova, G. Grechko, G. Nechitailo, and A. Mashinsky, Systems of chemical reactions depending on gravity,Akademiia Nauk SSSR Doklady 303: 1004-1007 (1988).Google Scholar
- 2.Sh. Abdurakhmanov, L. Bogatyreva, V. Briskman, M. Levkovich et al. On polyacrylamide gel formation by photoinitiation under terrestrial and orbital conditions, in: Numerical and Experimental Modeling of Hydrodynamic Phenomena under Weightlessness, Sverdlovsk (1988) pp. 120-128.Google Scholar
- 3.L. Bogatyreva, V. Briskman, K. Kostarev, V. Leontyev, et al., Heat/mass transfer mechanisms of the polymerization under terrestrial and microgravity conditions, in: Proceedings of the VIII European Symposium on Material and Fluid Sciences in Microgravity, European Space Agency, Brussels, ESA SP-333, 1:173-178(1992).Google Scholar
- 4.V. Golubev, D. Gromov, L. Guseva, B. Korolev, K. Kostarev, and T. Lyubimova, Free convective heat and mass transfer in processing polymer materials, Heat Transfer Research 25: 888-893 (1993).Google Scholar
- 5.A. Malkin, V. Begishev, L. Guseva, and K. Kostarev, Cross-linking inhomogeneity of oligomers caused by convection, J. Polymer Science A36: 625-630 (1994).Google Scholar
- 7.V. Briskman, K. Kostarev, V. Moshev, V. Begishev, and G. Nechitailo, Production of polymer materials with prescribed properties in microgravity, STAG Research Number BT-10, NASA-RSA Conference Abstracts, Moscow, 136 (1996).Google Scholar
- 9.V. Briskman, K. Kostarev, V. Levtov, V. Romanov, and T. Yudina, Comparative experimental research of polymerization on the “MIR” orbital station and on the Earth, AIAA 95-0263, American Institute of Aeronautics and Astronautics, 33rd Aerospace Sciences Meeting and Exhibit, Reno (1995).Google Scholar
- 11.V. Ivanov, V. Begishev, L. Guseva, and K. Kostarev, Front photopolymerization at constant extinction and limited mass transfer, J. Polymer Science B37: 293-296 (1995).Google Scholar
- 12.V. Briskman, K. Kostarev, and T. Lyubimova. Gel polymerization under high gravity conditions, in: Materials Processing in High Gravity, L.L. Regel and W.R. Wilcox, eds., Plenum Press, NY (1994) pp 185-192.Google Scholar
- 13.V. Briskman, K. Kostarev, and T. Yudina, Comparative investigations of thermal and photopolymerization under action of centrifugal forces. Basic mechanisms of heat/mass transfer, in: Centrifugal Materials Processing, L.L. Regel and W.R. Wilcox, eds., Plenum Press. NY (1997) pp 247-255.Google Scholar
- 14.K. Kostarev and A. Shmyrov, Investigations of flow structures and conversion distributions during photopolymerization in centrifugal fields,Winter School of Continuous Media Mechanics, Perm, (1999)197.Google Scholar