Poly specific gravity

A poly(tribromostyrene) with the bromine atoms attached to the benzene ring is marketed by the Ferro corporation as F yro-Chek 68 PB as a heat-resisting fire retardant used in conjunction with antimony oxide. The polymer has an exceptionally high specific gravity, reputedly of 2.8, and a softening point of 220°C. 

Vaterite is thermodynamically most unstable in the three crystal structures. Vaterite, however, is expected to be used in various purposes, because it has some features such as high specific surface area, high solubility, high dispersion, and small specific gravity compared with the other two crystal systems. Spherical vaterite crystals have already been reported in the presence of divalent cations [33], a surfactant [bis(2-ethylhexyl)sodium sulfate (AOT)] [32], poly(styrene-sulfonate) [34], poly(vinylalcohol) [13], and double-hydrophilic block copolymers [31]. The control of the particle size of spherical vaterite should be important for application as pigments, fillers and dentifrice. 

Fig. 8.2 Plot of increase in modulus against volume fraction for a wide variety of nanocarbon/poly-mer systems. Volume fractions calculated from reported mass fractions assuming specific gravities of 1.8, 2.1 and 1 for CNT, graphene and matrix, respectively. Short fiber data from [16] and [17]. Moduli of individual layer graphene (lTPa) and reduced-graphene oxide (250GPa) included for reference.

C poly 1,4-isoprene has a specific gravity of 0.91, a coefficient of linear expansion of 67 X 10 9 cm/cm C, and a refractive Index of 1.5191. This and other elastomers retain their characteristic mobility at temperatures above the Tt. They are brittle at temperatures below Tg. 

The specific gravity decreases as the size of the alkyl substituent increases e.g., the specific gravity of poly-/Mnethylstyrene is 1.01, compared with 1.0S for PS. 

The test device for specific gravity consists of an absorbent cellulose pad impregnated with bromthymol blue, poly-methylvinyi ether and/or maleic anhydride, and sodium hydroxide. The test depends on the apparent pK change of the pretreated polyelectrolyte in relation to ionic strength the hydrogen ions released are detected by the pH indicator. The color changes from a dark blue at a low specific gravity... 

In addition to PET, several other polyester systems have been evaluated for fiber use. Of these, only poly(cyclohexy1 diraethylene terephthalate) (PCHDT) appears to have achieved commercialization. The PCHDT may be prepared either by direct esterification or El processes with titanium alkoxide catalysts. The 1,4-bis(hydroxymethyl)cyclohexane, used as the diol in this polymer, is most commonly a mixture of cis and trans isomers in a ratio of approximately three to seven. Because of the greater steric requirements of the cyclohexyl ring, PCHDT has a higher viscosity and higher resilience than PET. It is also easier to dye. Its specific gravity is approximately 1.22 as compared to 1.38 for PET. 

By TEM of the poly-lipid liposome/lipid-heme the diameter was ca. 350 A (Fig. 9) and it did not change before and after the polymerization. The gel permeation chromatography and the ultracentrifugation of the liposome/heme showed that all of 77 was entrapped within the liposome. Solution properties of the poly-lipid liposome/ lipid-heme were almost the same as those of human blood specific gravity 1.012, viscosity 3.75-4.12 cp, and osmotic pressure 334 mOsm. The solution of the polylipid liposome/lipid-heme was stable and could be stocked for months without precipitation and change of the particle size, i.e. without aggregation and fusion of the liposome, at ambient temperature. 

Some characteristic properties of poly(DiPF) as a typical poly(DRF) are summarized [3] It is colorless powder, soluble in many organic solvents, and a transparent film is obtained by casting of the solution. Specific gravity 1.12 g/cm Refractive index 1.4698. Miscible with poly(MMA). Hydrolysis is difficult. Tlnit = 223 C, Tmax = 300 C, Tg and 7m are not detected below the decomposition temperature. Viscosity relationship [v] - 7.53 X dL/g in benzene at 30 C [26]. Persistence length 7.6... 

Poly ether TPUs are slightly lower in specific gravity than polyester and polycaprolactone grades. They offer low temperature flexibility and good abrasion and tear resilience. They are also durable against microbial attack and... 

Figure 6.9. Yield strength/specific gravity of unfilled poly(benzoyl-l,4-phenylene) compound to 316 stainless steel, 6061-T6 and 7075-T6 aluminium, and 6A1-4V titanium (Reprinted with permission from ref. 66).

Poly-3,3-bis(chloromethyl)oxacyclobutane is a hard, rigid material with specific gravity 1.4. The mechanical properties of the polymer are not particularly outstanding when compared to those of other plastics materials however, there are no particular limitations, apart from a somewhat low impact strength. As will be noted later, most applications of the polymer arise from its very good chemical resistance rather than from its mechanical properties. 

Polymer systems with the lowest specific gravities are the polypropylenes and poly-ethylenes the highest are the fluoroplastics and the acetals. 

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