Polydimethylsiloxane Density

Polyisobutylene and similar copolymers appear to "pack" well (density of 0.917 g/cm ) (86) and have fractional free volumes of 0.026 (vs 0.071 for polydimethylsiloxane). The efficient packing in PIB is attributed to the unoccupied volume in the system being largely at the intermolecular interfaces, and thus a polymer chain surface phenomenon. The thicker cross section of PIB chains results in less surface area per carbon atom. 

Initiation of stannous octoate-catalyzed copolymerization of e-caprolactone with glycerol was used to prepare a series of trifunctional hydroxy-end blocked oligomers, which were then treated with hexane-1,6-diisocyanate to form elastomeric polyesterurethanes with different crosslink densities (49). Initiation of e-caprolactone polymerization with a hydroxypropyl-terminated polydimethylsiloxane in the presence of dibutyl tin dilaurate has been used to prepare a polyester-siloxane block copolymer (Fig. 4) (50). 

Fig. 10 Plots of Le/f-cw vs. dimensionless graft density a (1) PS brushes prepared by adsorption of PS-polydimethylsiloxane block copolymers (Mw,ps = 60000) and 0 (Mw,ps = 169000) [21,22]. (2) PEO brushes prepared by adsorption of PEO-PS block copolymers A (Mw.peo = 30800) and V (Mw.peo = 19600) [201]. (3) PMMA brushes prepared by surface-initiated ATRP (M = 31 300 267400). Data reprocessed from [116,117]...

Santra RN et al. (1993) In-situ compatibilization of low-density polyethylene and polydimethylsiloxane rubber blends using ethylene-methyl acrylate copolymer as a chemical compatibilizer. J Appl Poly Sci 49(7) 1145-1158... 

Figure 9.3 Weight loss as a function of exposure time with oxygen glow discharge POM polyoxymethylen, PMMA poly(methyl methacrylate), PET poly(ethylene terephthalate), LDPE low density polyethylene, SR silicone rubber (polydimethylsiloxane).

Summary The fluorescence behavior of covalent bonded probes was investigated in linear and crosslinked polydimethylsiloxanes. The probe shows a dual emission that depends on the network density and the concentration on swelling agent. Investigations of linear polydimethylsiloxanes with a bonded probe as a function of TUF concentration indicate the existence of ground state complexes between the solvent and the probe molecule. 

FIGURE 16.10 Pressure-composition phase diagram for the system polydimethylsiloxane (PDMS) — -pen-tane with the SAFT equation of state. Using PDMS pure-component parameter sets, which reproduce the PDMS densities well, no acceptable reproduction of the binary equilibria is possible. (From Pfohl, O. et al., Fluid Phase Equilibria, submitted, 2001. With permission.)... 

Table 3.1.2 Examples of passive sampling devices available for monitoring the chemical qnality of environmental waters (Greenwood et at., 2007 Onyang and Pawliszyn, 2007 Seethapathy et at., 2008). LDPE low-density polyethylene PDMS polydimethylsiloxane SDP-RPS styrenedivinyl-benzene - reverse phase snlphonate...

Lipids have proven to be quite active in polymer environments (13-15). Investigations in the 1960 s performed on silicone rubber heart valve poppets (16) demonstrated that polydimethylsiloxanes with low cross-link densities and low silica filler underwent significant lipid uptake in vivo. 

PDM-0421, PDM-0821, PDM-1922. See Phenylmethyl polysiloxane PDM-704, PDM-7050. See Tetramethyl tetraphenyl trisiloxane PDMS. See Polydimethylsiloxane PDX-84367. See Polyetherimide resin PDX-84368. See Polycarbonate PDX-84369. See Polybutylene terephthalate PE-25. See Polyethylene, medium density PE. See Pentaerythritol Polyethylene PEA P-PEA. See Phenethyl alcohol Peach aldehyde. See y-Undecalactone Peach kernel extract. See Peach (Prunus persica) kernel extract... 

Dimethoxymercaptopropyl-terminated polydimethylsiloxane homopolymer (Mercaptopropyl) methylsiloxane-dimethylsiloxane copolymer lubricant, semirigid PVC food-contact Pentaerythrityl adipate-stearate lubricant, semi-synthetic metalworking lubricants Sorbitan tritallate lubricant, sewing Polyethylene, high-density lubricant, sewing thread Isopropyl myristate... 

Silicones Silicone rubbers and oils are usually based on polydimethylsiloxane (Si(CH3)20) . They all give spectra readily identified through the positive ions at miz 28, 47, 147, 107, 221, and 281. The relative intensities of these peaks vary as a function of molecular weight, end groups, and cross-link density in the rubbers. 

A point worth noting here is that several of the molecular models that will be described in the subsequent sections are Neo-Hookean in form. Normally, dry rubbers do not exhibit Neo-Hookean behavior. As for the Mooney-Rivlin form of strain energy density function, rubbers may follow such behavior in extension, yet they do not behave as Mooney-Rivlin materials in compression. In Fig. 29.2, we depict typical experimental data for a polydimethylsiloxane network [39] and compare the response to Mooney-Rivlin and Neo-Hookean behaviors. The horizontal lines represent the affine and the phantom limits (see Network Models in Section 29.2.2). The straight line in the range A <1 shows the fit of the Mooney-Rivlin equation to the experimental data points. 

FIGURE 60.6. (a) Phonon velocity in linear polydimethylsiloxane as a function of the molecular weight, (b) Phonon velocity in rubbery PDMS as a function of cross-link density. Here Oc is the average number of monomer units between cross-links and is directly proportional to Me [11]. Reprinted with permission from Shingo Kondo and Takashi Igarashi, Journal of Applied Physics, 51, 1514 (1980). Copyright 1980, American Institute of Physics. 

Z. Bayraktar and E. Kiran, Miscibility and phase separation in polydimethylsiloxane + carbon dioxide Demixing pressures and densities. 

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