Filled IPNs

Lipatov et prepared a series of sequential IPNs, sometimes 

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While the LA is primarily a molecularly based quantity for pure materials, graphite filled IPNs and many other composite structures have been shown to exhibit greater LA s than the neat material (17). Morphological effects on the loss area are not considered by the group... 

Figure 12 shows the temperature dependence of the logarithmic decrement of neat IPN and filled IPN. The logarithmic decrement of neat IPN showed relative high attenuation, while filled IPN prepared by adding platelet fillers showed an even higher attenuation over a wide temperature range. 

Judging from the results of dynamic mechanical analyses, IPNs showed more effective damping properties than commercial chloroprene rubber at elevated temperatures. In addition, filled IPNs prepared by adding platelet fillers showed even higher attenuation (logarithmic decrement). 

Yu. S. Lipatov, Role of Interfacial Phenomena in the Formation of Micro and Macro-Heterogeneities in Multicomponent Polymer Systems, PureAppl. Chem. 43,273 (1975). Review of blends and filled IPNs. Physical properties, electron microscopy. 

Viscoelastic properties of filled IPNs have been studied,using various fillers (fumed silica, aluminum oxide, dispersed cured poly(ester acrylate) in the... 

Table 7.4 Modulus, E, glass transition temperature, Tg, and segregation degree, a, of filled IPNs based on polyurethane, PU, and poly (ester acrylate), PEA...

Thus, for filled IPNs, the same effect of increased compatibility in the filler presence is observed, which is typical of alloys of linear polymers. These effects are connected with the filler influence both on the phase separation during system formation stage and on the reaction kinetics. 

A special problem in the chemistry and physics of IPNs is their reinforcement. This process is tightly connected with the behavior of IPNs at the interface with solid (filler). Physicochemical problems of the filled IPNs were reviewed in [326]. Here, we consider only the filler effect on the kinetics of IPN formation. 

The following data is the result of a series of high temp storage (stability) expts conducted by (Brit) Imp Chem Inds Ltd (Ref 6) on IPN a) A summary for a series of pressure development tests involving a steel vessel of lOOcc capacity, half filled with IPN, and maintained at a given temp for four hours is presented below ... 

See also Biodegradable polymer networks Filled silicone networks Interpenetrating networks (IPNs) Model silicone networks Monodisperse model networks ... 

An ethylene homopolymer (Allied Corporation) was also used as a filler for the IPNs. A 10% addition of this material to the 50/50 urethane/epoxy IPN sample had similar effects as those shown by the 10% mica-filled sample of Figures 7 and 8. A clear difference in this case was a shift of the loss tangent peak to lower frequencies, resulting in a lower tan A value in the frequency range of the display, (see Figure 12). 

As discussed earlier, while the scale of the fillers is substantially different, nanocomposite materials concepts and technology are very similar to those of conventional composite materials. This is clearly demonstrated in the case of new thermosets for nonlinear optical (NLO) applications, " " where nanocomposite of liquid crystalline thermosets, IPNs, and simple filled thermosets are evaluated. Tripathy et al. discussed four different ways to prepare nonlinear optical polymers. (1) The polymer matrix is doped with NLO moieties in a guest/host system (2) In side-chain polymer systems, NLO polymers with active moieties are covalently bonded as pendant groups (3) In the main chain polymer, the chromo-phores are incorporated as parts of the main polymer backbone to enhance the temporal stability of the NLO properties and (4) Stability of the optical noninearity in sol-gel-based thermosets is related to... 

The crosslinking reaction may be catalyzed by a small amount of suitable organometalUc catalysts. The blends typically contain ca. 5-20% silicone. Injection molded or extruded parts are further heat-treated to complete the curing reactions. There is, of course, a significant level of phase separation. In the thermoplastic molding compounds such as glass-filled PA and PBT, addition of the silicone semi-IPN in small amounts (ca. 5-10%) is reported to reduce the mold shrinkage, improve mold release, and increase wear and friction resistance. Polyamide-silicone blends have already been discussed under PA blends section. 

Starting in the late 1960s, the field of IPNs was examined by three teams of investigators. Papers by Frisch et al. on lENs (1969a, b), Sperling and Friedman on sequential IPNs (1969), and Lipatov and Sergeeva (1967) on filled materials started systematic research to establish the field of IPNs. By the year 1979, there were... 

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