Filler titania

Some elucidation of the mechanism of elastomer reinforcement is being obtained by precipitating chemically-generated fillers into network structures rather than blending badly agglomerated filler particles into elastomers prior to their cross-linking. This has been done for a variety of fillers, for example, silica by hydrolysis of organosilicates, titania from titanates, alumina from aluminates, etc. [85-87], A typical, and important, reaction is the acid- or base-catalyzed hydrolysis of tetraethylorthosilicate ... 

Ground fillers (zinc oxide, titania magnesia, alumina)... 

Figure 8.4 Stress-strain isotherms for PDMS networks reinforced with in situ generated titania particles.39 Each curve is labeled with the wt % of filler introduced, and filled circles locate results used to test for reversibility.

Figure 8.5 Plot of volume fraction ratio Vro/Vrf characterizing the swelling of an unfilled PDMS network relative to that of a filled PDMS network, against filler loading expressed as volume ratio of filler to PDMS is the volume fraction of filler).40 Types of filler were silica-titania mixed oxides ( ), silica (O), and titania (A).

Nanooxides such as fumed silica, titania, alumina, etc. (with spherical primary nanoparticles) are used as fillers for complex drugs, enterosorbents, vaccine adjuvants, food additives, etc.1,2 In general nonporous spherical nanoparticles can adsorb solutes in low amounts because the desolvation effect causes an... 

The most important oxide of titanium is the dioxide, Ti02, also known as titania. This importance arises predominantly from the use of Ti02 as a white pigment in the mannfacture of paint and paper and as a filler in rubber and plastics. Titanium... 

Solomon, D. H., and D. G. Hawthorne. Chemistry of pigments and fillers. Chapter 2, p. 51, in Titania Pigments. New York John Wiley ... 

Silica coatings are applied to particulate materials to modify surface characteristics that interfere with the exploitation of desired bulk properties, as with titania pigments that may photocatalyze the degradation of their vehicle, surfaces of selective zeolite catalysts that may promote undesired reactions, and fillers for plastics that may not disperse in their matrix. 

Titania. Titania powders are used as pigments, catalytic supports, membranes, opacifiers, photocatalysts and fillers in industrial applications . Titania particles have been prepared by a number of methods, such as hydrolysis, sol-gel, microemulsion and hydrothermal synthesis. Titania exists naturally in two tetragonal forms, the metastable phase anatase, and the stable phase rutile. On heat treatment, anatase transforms into rutile. The phase transition temperature depends on the starting materials and the preparation procedure. 

Titania and Ti02/Si02 (Unmodified and Modified) Used as Fillers to Ethyl Cellulose and Nitrocellulose on the Tests of Adhesion, UV Stability, Corrosion Resistance, and Water Absorption of Filled Films... 

Analysis of rubber filled with conventional filler and an in situ filled siloxane sample displayed three levels of structure in the size-range observed [51]. In another study, growth mechanism and structures of siloxane composites containing silica, and silica-titania were studied by Breiner et al. using SAXS. Both systems were found to yield dense particles. 

The direct and indirect effects of fillers oti the photostability of polymer compositions are well known. With the recent interest in nanopowdered fillers reports of their effectiveness as photostabilizers is beginning to be reported in the literature. For instance ZnO and Ti02 nanoparticles (primary particle size 25-70 nm) were studied in acrylic coatings. A layer that carried at least 5 weight percent of the nanoparticles was needed to shield the underlying layers from UV exposure and hence degradation [162]. Nanoscale titania was also evaluated as a stabilizer in epoxy coatings [163]. 

Research efforts on filled polymer blends have been more focused on nanopartide-filled systems [42, 43]. One usual observation is the same as those with microscopic fillers - polar nanofillers localize in more polar phases [44—53]. In cases where both phases are polar or nonpolar, the filler particles have been observed to be expelled from both phases in the blend [54—56]. Selective localization of nano-sized partides has been an interesting topic of research. We discuss some of the results here. Gahleitner et al. [57] observed a preferential localization of clay particles in PA6 droplets in PA6/PP blends. Recall that day, espedally montmorillonite, is highly polar in both its pristine and various organically modified forms [58-62]. Similarly, Wang et al. [63] reported selective localization of clay particles in maleic anhydride grafted ethylene-propylene-diene (EPDM-MA) rubber droplets in poly(trimethylene terephthalate)/EPDM-MA blends. Selective localization of fillers other than clay particles has also been reported. Eor instance, Ou and Li [64] observed that toluene diisocyanate modified titania particles selectively localized in PA6 droplets in PP/ PA6/titania blends. 

Several inorganic fillers/organic additives, such as silica, talc, kaolin, CaC03, titania, zeolites, cross-linked acrylic copolymers, spherical silicon beads, and so on, are employed in the plastics/coatings industry to attain the desired blocking performance. Some of these fillers are discussed elsewhere in this book in terms of their primary function only amorphous silica forms (natural and synthetic), used for antiblocking, will therefore be discussed in this chapter. 

---