Organotin fibers

Cellulose can be modified with organostannane chlorides, such as dibutyl or triphenyl derivatives [91,92], or with organotin halides in the presence of bisethylenediamine copper(II) hydroxide [93]. Epoxy-activated cellulose was prepared by reacting cellulose acetate fibers with sodium methoxide, followed by reacting it with epichlorohydrin in DMSO. This epoxy-activated cellulose has proved to be a useful intermediate to react with substances containing active hydrogen, such as amine, amino acid, or carboxylic acids [94], as shown in Fig. 3. Epoxidized cellulose has also been converted to a thiol derivative via reduction of a thiosulfate intermediate [95], and sulfoethylcellu-[ose has been obtained from sodium chloroethanesulfonate [96]. Cellulose... 

SPME capillary gas chromatography (SPME-GC) can be used for the extraction of organometal compounds after these have been derivatized to a sufficiently volatile form (see also organotin speciation). A silica fiber coated with polydimethylsiloxane (PDMS) is brought into the (headspace) of the sample. After exposure, the fiber is inserted into the GC injection port and the compounds are thermally desorbed for subsequent analysis. This method has higher sensitivity compared to the injection of solvent on a capillary column (usually 1 fil) but requires the use of standard addition as a calibration method. After GC separation, analysis can be performed by furnace atomization plasma emission spectrometry (FARES)." ... 

A number of methods have been reported in the literature for improving the thermal stability of acrylic fibers. For example, impregnating wet-spun fibers in the gel state with salts of metals from group II in the periodic table of the elements [496] or sodium sulfide solution [487] have been reported. Also, dried fiber can be impregnated with sulfuric acid solutions of formamide [488], phosphates or borax [489], or organotin salts [490]. 

Recently, we noticed a number of fiber-forming products, some derived from acyclovir and various metallocene dichlorides such as vanadocene [3], and niobocene (4) [4]. The formation of fibers from a simple organotin polyether and from other organotin products is described here. 

As part of an effort to better understand the structural requirements for forming fibers, we surveyed a number of organotin polymers. Table 18.2 contains the results of this survey. 

Table 18.2 Fiber forming capability of selected organotin polymers... 

Solid phase microextraction (SPME) involves extraction onto a thin fiber and the technique has become more prevalent recently and additionally provides a preconcentration of analytes prior to analysis. The fibers used in the technique can be coated with a range of stationary phases and a nonpolar phase such as polydimethylsiloxane (PDMS) is typically used for the extraction of derivatized organotin species. An equilibrium is established between the sample extract solution (or the headspace above the solution) and the stationary phase coating the fiber. The analytes are then typically desorbed from the fiber for analysis, for example, using thermal desorption during GC analysis. The technique allows rapid and solvent-free extraction of the analytes. Very good extraction has been achieved for water samples however, the technique has been shown to be more variable with more complex matrices. 

The primary nutrient in flexible PVC is the plasticizer. Epoxidized natural oils arc easily metabolized by a variety of bacteria and fungi. In some cases, hquid epoxy resins can be substituted for, for example, ESO, improving microbial resistance. Since epoxy resins usually add tack, revision of the lubricant system may be required. In filled or pigmented compounds, it would be preferable to use an acid absorber such as hydrotalcite or zeolite in place of ESO, or a stabilizer system based on such ingredients. This is also possible in translucent compounds such as shower crrrtains. Polyol components of stabilizers, such as pentaerythritol, are also nutrients. As with rigid PVC/wood fiber composites, the ideal stabilizer would be a combination of organotin carboxylate and hydrotalcite or zeolite, hr many cases, the required material cost... 

Discoloration, however, remains an issue with vinyl wood fiber composites for outdoor application. UV light absorbers for vinyl are discussed in Section 4.5. Hindered amine stabilizers resistant to hydrogen chloride are now available, but require more expensive organotin carboxylate, rather than mercaptide, stabilizers, since they interact with the latter. A useful alternative is to include the hindered amine stabilizer in an acrylic or ASA topcoat over the wood fiber composite. 

At the stage of capron polymerization, an antibacterial organotin compotmd (tri-butyltin oxide or hydroxide) is added that retains the antibacterial effect after multiple laimdries. Methods of imparting antimicrobial properties to textile materials by injection of nitrofuran compounds irrto spinning melts with further fixing them at molding in the fine stmcture of fibers sirrrilar to clathrates were designed. 

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