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Cyclic dimethylsiloxanes, properties

Cyclic compounds, unnatural, 24 59 Cyclic cooligomerization, 16 238 Cyclic corrosion tests, 16 218 Cyclic diacyl peroxides, 18 473, 477 Cyclic dimethylsiloxanes, 22 575 Cyclic diperoxides, 18 461 Cyclic diperoxyketals, 18 457 Cyclic disulfides, antimicrobial properties of, 23 713... [Pg.241]

The evidence is strengthened by the preparation from the cyclic trimer or tetramer of the related linear compounds (PNCUin PCI-, (Section II, C), which have quite different properties. The stable existence of such large rings has in any case seemed less unreasonable since the isolation of the separate members of the cyclic dimethylsiloxane series (Me2SiO) up to the nonamer, which has a 18-membered ring (see p. 80 in ref. 65). [Pg.369]

Another Py-GC/MS experiment was performed on polyacrylic /nfer-net-polysiloxane, a copolymer used as impact properties modifier. This is a polymer of butyl acrylate with low levels of allyl, methyl, and 3-(dimethoxymethylsilyl)propyl methacrylates interpenetrated with cyclic dimethylsiloxane. The copolymer has CAS 143106-82-5. The pyrolysis was done at 600 C in He similar to other experiments previously discussed. The pyrogram is shown in Figure 6.7.14 and peak identification is given in Table 6.7.10. [Pg.361]

Unlike the linear analogues, cyclic dimethylsiloxanes are low melting solids and the Tm generally decreases with increasing ring size. Physical properties for a series of M-stopped oligomers, MDj M, and cyclic compounds, D , are listed in Table 3. [Pg.7599]

The dilute solution properties of cyclic diblock copolymers of styrene and dimethylsiloxane have been investigated by Amis and coworkers [316,317].The apparent temperature in cyclohexane of the cyclic diblocks was found to be about... [Pg.117]

The most effective method of modification of linear organosilicon polymers is the insertion of various elements or groups with a different chemical nature into the structure of the macromolecular chain. As a result of the insertion in the dimethylsiloxane chain of different fragments there are changes in the physical chemical properties [5]. The insertion of the cyclic fragments in the main linear dimethylsiloxane chain hinder the chain transfer reactions, which proceed with the release of D -type (where D = Me2SiO) cycles during the thermal depolymerisation, that raises the thermal-oxidative stability of the polymers [6]. [Pg.142]

Selected properties of the cyclic poly(dimethylsiloxanes) (r) compared to linear poly(dimethylsiloxanes) (I)... [Pg.437]

As glass and quartz exhibit the same surface property as fused-silica capillary, the monolithic materials could be conveniently prepared in a glass- or quartz-based microfluidic device via the same way of monoliths in the capillary. However, glass/quartz devices are rather expensive, and the need for specialized facilities for their fabrication with conventional photolithography technology hinders any rapid modification of the chip architecture. An attractive alternative is using a variety of polymeric materials, such as poly(dimethylsiloxane) (PDMS), poly(methyl methacrylate) (PMMA), polycarbonate (PC), and cyclic olefin copolymer (COC), to fabricate microchips for their mechanical and chemical properties, low cost, ease of fabrication, and high flexibility. [Pg.1896]

Garrido, L. Mark, J. E. Clarson, S. J. Semiyen, J. A., Studies of Cyclic and Linear Poly(dimethylsiloxanes) 17. Elastomeric Properties of Model PDMS Networks Containing Either Cyclics or Linear Chains as Diluent. Polym. Comm. 1985,26(2), 55-57. [Pg.201]

Huang, W. Frisch, H. L. Hua, Y. Semiyen, J. A., A Study of the Properties and Topological Trapping of Cyclic Poly(dimethylsiloxane) in Poly(2,6-dimethyl-1,4-phenylene oxide) Networks. J. Polym. Set, Part A Polym. Chem. 1990,... [Pg.201]

Various approaches have been taken to improve the properties of fluorosilicones. In this connection, Kobayashi et al. [17] synthesized several methyl-3,3,3-trifluoropropylsiloxane (F)-dimethylsiloxane (D) random and block copolymers. The random copolymers were prepared by equilibrium copolymetization starting from a mixture of cyclic F and D siloxanes with potassium silanolate as the catalyst The F-D block copolymer was prepared by sequential anionic living polymerization of strained cyclotrisiloxanes using a much weaker catalyst, lithium silanolate. The prepared copolymers were soluble in both tetrahydrofuran (THF) and... [Pg.272]

The conformational and dynamic properties of cyclic polymers have been the subject of considerable interest over a number of years [73] [74]. The new synthetic procedure developed for the preparation of per-deuterated cyclic and linear poly(dimethylsiloxane) (PDMS) polymers [12] [13] [14] now offers unique possibilities for neutron scattering studies. For the first time, it has allowed sufficient deuterated materials to be available for fractionation using our preparative GPC instrument. The resulting narrow fractions are ideally suited for both static and dynamic studies of cyclic and linear polymers. This range incorporates the critical molar mass for entanglement in PDMS. [Pg.77]

Huang, W., Frisch, H.L., Hua, Y., and Semiyen, J.A. (1990) A study of the properties and topological trapping of cyclic poly(dimethylsiloxane) in poly(2,6-dimethyl-l,4-phenylene oxide) networks. Journal of Polymer Science Part A-Polymer Chemistry, 28,1807—1812. [Pg.816]


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See also in sourсe #XX -- [ Pg.64 ]




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