Polymerization of a silacyclobutane having an epoxy moiety and its application to networked polymer synthesis were examined. Four-membered ring-opening polymerization of silacyclobutane having a 3,4-epoxybutyl group on the silicon atom (OBMSB) was achieved by using a platinum vinyldisiloxane complex with keeping the epoxy ring unchanged. Copolymerization of 1,1-diethylsilacyclobutane (DESB) with OBMSB by using the same catalyst effectively gave the corresponding copolymers [poly(DESB-co-OBMSB)]. Thermal properties of the polyOBMSB, polyDESB, and poly(DESB-co-OBMSB) were investigated by DSC and TGA. Cast films of the obtained polymers with 1naphthylmethylmethyl-p-hydroxyphenylsulfonium hexafluor-oantimonate, a small amount of thermally latent acid generator were prepared. Heating the films at 80 C for 2 h gave crosslinked networked polycarbosilanes through cationic ring-opening of the epoxy moieties. Thermal and mechanical properties of the networked polymers were investigated by TGA, DSC, and tensile strength measurements.

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Rotordynamic characteristics of a centrifUgal impelIer acting on whirling motion make some influence on rotor vibration ． To investigate the rotordynamic characteristics ， rotordynamic fbrces on whirling open − type ！ closed impeller were measured by the rotordynamic test stand with active magnetic bearings ． Experiments were conducted under the various rotor conditions such as flow rates ， rotational speeds ， dynamic eccentricity ofthe rotor and tip clearances ． Test result shows the tangential fbrces ofthc closcd impeller are more sensitive to the operating conditions of the rotor than that ofthe open − type impeller ． And finally ， the differences ofthe phase ofthe fluid fbrces between both impellers are also discussed ，